TW201307265A - Reducing acetals during ethanol separation process - Google Patents

Abstract

To reduce acetal concentrations when separating ethanol from a crude product in one or more distillation column, at least one of the columns is operated at a higher pressure to increase the equilibrium constant that favors hydrolysis of the acetal. The crude product may comprise ethanol, acetaldehyde, water and one or more acetals, such as diethyl acetal. The acetal concentration may be reduced thus reducing the need to separate acetal from the crude product.

Description

Process for reducing acetals in ethanol separation Priority claim

The present application claims priority based on U.S. Patent Application Serial No. 13/197,737, filed on Aug. 3, 2011, filed on Aug. U.S. Patent Application Serial No. 13/197,693, the entire disclosure of which is incorporated herein by reference.

The present invention is generally directed to a process for making ethanol, and more particularly to a process for separating ethanol from a crude product to reduce the concentration of acetal in one or more distillation columns operating under pressure.

Industrial ethanol is prepared from petrochemical sources such as petroleum, natural gas or coal, or from source intermediates such as syngas, or from starchy materials or cellulosic materials such as corn or sugar cane. . Conventional methods for producing ethanol from petrochemical sources and from cellulosic materials include ethylene acid catalyzed hydration, methanol homologation, direct alcohol synthesis, and Fischer-Tropsch synthesis. The unstable price of petrochemical sources has caused the price of ethanol produced by the float to fluctuate, which makes it more demanding for alternative sources of ethanol production when the source price increases. Starch materials and cellulosic materials are converted to ethanol by fermentation. However, fermentation is generally used in the manufacture of consumer ethanol, whereby the ethanol produced is suitable for fuel or human consumption. In addition, fermentation of starchy or cellulosic materials competes with food sources and limits the amount of ethanol that can be made for industrial use.

The manufacture of ethanol via reduction reactions of alkanoic acids and/or other carbonyl containing compounds has been extensively studied, and various combinations of catalysts, supports, and operating conditions are described in the literature. When reducing an alkanoic acid such as acetic acid, other compounds will form with ethanol or in the opposite Should be formed. These impurities limit the production and recovery of ethanol from this reaction mixture. For example, during hydrogenation, the esters are produced together with ethanol and/or water to form an azeotrope which will be difficult to separate. Furthermore, when the conversion is incomplete, the unreacted acid will remain in the crude ethanol mixture, which must be removed to recover the ethanol.

European Patent EP02060553 describes a process for the conversion of hydrocarbons to ethanol comprising the conversion of hydrocarbons to acetic acid and the hydrogenation of acetic acid to ethanol. The stream obtained from the hydrogenation reactor is separated to obtain an ethanol stream, and a stream of acetic acid and ethyl acetate which will be recycled to the hydrogenation reactor.

U.S. Patent No. 3,102,150 discloses the use of hydrogenation catalysts and cation exchange resins to hydrogenate aldehydes to alcohols to reduce the formation of acetals.

There is still a need for an improved process for recovering ethanol from crude products obtained by reducing alkanoic acids such as acetic acid and/or other carbonyl containing compounds.

In a first specific embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form acetaldehyde, ethanol, water and diethyl condensate. A crude mixture of aldehydes of ethanol; and separating the crude mixture of ethanol in one or more columns to recover an ethanol product comprising less than 1% by weight of diethyl acetal, wherein at least one of the columns is operated above atmospheric pressure. In one embodiment, the ethanol product may comprise from 0.0001 to 0.01% by weight of diethyl acetal.

In a second specific embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; and separating in a first distillation column A portion of the crude ethanol mixture produces a first residue comprising an alkanoic acid and a first distillate comprising ethanol and acetaldehyde. A portion of the first distillate is further separated in a second distillation column operating at atmospheric pressure to produce a second residue comprising ethanol and a second distillate comprising acetaldehyde. The second residue comprises less than 1% by weight of diethyl acetal.

In a third embodiment, the invention relates to a method for producing ethanol comprising providing a crude ethanol mixture comprising acetic acid, acetaldehyde, ethanol, water and diethyl acetal; Separating a portion of the crude ethanol mixture in the column to produce a first residue comprising acetic acid and a first distillate comprising ethanol and acetaldehyde; and separating the portion in a second distillation column operating at above atmospheric pressure The first distillate produces a second residue comprising ethanol and a second distillate comprising acetaldehyde, wherein the second residue comprises less than 1% by weight diethyl acetal.

In a fourth specific embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; and a separation section in the first distillation column Part of the crude mixture of ethanol to produce a first residue comprising an alkanoic acid and a first distillate comprising ethanol, water, ethyl acetate and acetaldehyde; in a second distillation column operating at above atmospheric pressure Part of the first distillate to produce a second residue comprising ethanol and water and a second distillate comprising ethyl acetate and acetaldehyde; and the second portion of the separated portion in the third distillation column being operated The residue produces a third residue comprising water and a third distillate comprising ethanol, wherein the third distillate comprises less than 1% by weight of diethyl acetal.

In a fifth specific embodiment, the present invention relates to a method for producing ethanol, which comprises providing a crude mixture of ethanol comprising acetic acid, acetaldehyde, ethanol, water and diethyl acetal; and separating the portion of the ethanol in the first distillation column The crude mixture produces a first residue comprising acetic acid and a first distillate comprising ethanol, water, ethyl acetate and acetaldehyde; the first portion of the separated portion of the second distillation column operating at above atmospheric pressure Distillate to produce a second residue comprising ethanol and water and a second distillate comprising ethyl acetate and acetaldehyde; and separating a portion of the second residue in the third distillation column operated to produce A third residue of water and a third distillate comprising ethanol, wherein the third residue comprises less than 1% by weight of diethyl acetal.

In another embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; in the first distillation column, a separation section Part of the crude ethanol mixture to produce a first residue comprising a majority of the water fed to the distillation column and a first distillate comprising ethanol, acetaldehyde and water; removed from the first distillate Water to produce a stream of ethanol mixture; and separating a portion of the ethanol mixture stream in a second distillation column operating at above atmospheric pressure to produce a second residue comprising ethanol and a second distillate comprising acetaldehyde, wherein The second residue comprises less than 1% by weight of diethyl acetal.

In still another specific embodiment, the present invention relates to a method of producing ethanol, which comprises The alkanoic acid and/or its ester are hydrogenated in the presence of a catalyst to form a crude mixture of ethanol; a portion of the crude ethanol mixture is separated in the first distillation column to produce a feed comprising a majority of the distillation column. a first residue of water and a first distillate comprising ethanol, ethyl acetate, acetaldehyde and water; removing water from the first distillate to produce a stream of ethanol mixture; and operating at above atmospheric pressure Separating the first portion of the ethanol mixture stream in a second distillation column to produce a second residue comprising ethanol and a second distillate comprising ethyl acetate and acetaldehyde, wherein the second residue comprises less than 1 a second part by weight of diethyl acetal; separating a second portion of the ethanol mixture stream in a third distillation column operated at a pressure of from 0.1 kPa to 100 kPa to produce a third residue comprising ethanol and A third distillate comprising ethyl acetate and acetaldehyde, wherein the third residue comprises less than 1% by weight ethyl acetate; and the ethanol product is recovered from the second residue and/or the third residue.

In still another embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form ethanol, water, ethyl acetate, acetaldehyde. And a crude ethanol mixture of diethyl acetal; separating a portion of the crude ethanol mixture in the first distillation column to produce a first residue comprising a majority of the water fed to the distillation column and comprising ethanol, acetic acid a first distillate of ethyl ester, acetaldehyde and water; removing water from the first distillate to produce a stream of ethanol mixture; and separating a portion of the ethanol in a second distillation column operated at above atmospheric pressure Flowing the mixture to produce a second residue comprising ethanol and a second distillate comprising ethanol, ethyl acetate and acetaldehyde, wherein the second residue comprises less than 1% by weight of diethyl acetal; Separating a portion of the second distillate in a third distillation column operated at a pressure of 0.1 to 100 kPa to produce a third residue comprising ethanol and a third distillate comprising ethyl acetate and acetaldehyde, wherein the The three residues include less than 1% by weight of ethyl acetate; and Two residues and / or third residue recovering ethanol product.

In still another embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form ethanol, water, ethyl acetate, acetaldehyde. And a crude ethanol mixture of diethyl acetal; separating a portion of the crude ethanol mixture in the first distillation column to produce a first residue comprising water fed to the first distillation column and comprising ethanol a first distillate of ethyl acetate, acetaldehyde and water; removing water from the first distillate to produce a stream of ethanol mixture; operating at a pressure of from 0.1 to 100 kPa Forming a portion of the ethanol mixture stream in the second distillation column to produce a second residue comprising ethanol and a second distillate comprising ethyl acetate and acetaldehyde, wherein the second residue comprises less than 1 weight % diethyl acetal; separating a portion of the second distillate in a third distillation column operated at above atmospheric pressure to produce a third distillate comprising acetaldehyde and a third residue comprising ethanol Wherein the third residue comprises less than 1% by weight of diethyl acetal; and the ethanol product is recovered from the second residue and/or the third residue.

In still another embodiment, the present invention relates to a method for producing ethanol comprising providing a crude mixture of ethanol comprising acetic acid, water, acetaldehyde, ethanol, and diethyl acetal; and separating the portion in the first distillation column a crude mixture of ethanol to produce a first residue comprising a majority of water fed to the distillation column and a first distillate comprising ethanol, acetaldehyde and water; water is removed from the first distillate An ethanol mixture stream; separating a portion of the ethanol mixture stream in a second distillation column operated at above atmospheric pressure to produce a second residue comprising ethanol and a second distillate comprising acetaldehyde, wherein the second residue The inclusions comprise less than 1% by weight of diethyl acetal.

In still another embodiment, the invention relates to a process for the manufacture of ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; operating at above atmospheric pressure Separating a portion of the crude ethanol mixture in the first distillation column to produce a first residue comprising an alkanoic acid and a first distillate comprising ethanol and acetaldehyde; and the first portion of the separated portion in the second distillation column The distillate produces a second residue comprising ethanol and a second distillate comprising acetaldehyde, wherein the second residue comprises less than 1% by weight of diethyl acetal.

In still another embodiment, the invention relates to a method of making ethanol comprising providing a crude ethanol mixture comprising acetic acid, acetaldehyde, ethanol, and diethyl acetal; in a first distillation column operating at above atmospheric pressure Separating a portion of the crude ethanol mixture to produce a first residue comprising acetic acid and a first distillate comprising ethanol and acetaldehyde; and separating a portion of the first distillate in the second distillation column to produce a second residue of ethanol and a second distillate comprising acetaldehyde, wherein the second residue comprises less than 1% by weight of diethyl acetal.

In still another embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; Separating a portion of the crude ethanol mixture from the first distillation column operated at atmospheric pressure to produce a first residue comprising ethanol and water and a first distillate comprising ethyl acetate and acetaldehyde; and A portion of the first residue is separated in the column to produce a second residue comprising water and a second distillate comprising ethanol, wherein the second distillate comprises less than 1% by weight diethyl acetal.

In still another embodiment, the present invention relates to a method of producing ethanol comprising providing a crude mixture of ethanol comprising acetic acid, acetaldehyde, ethyl acetate, ethanol, and diethyl acetal; and operating at above atmospheric pressure Separating a portion of the crude ethanol mixture in a distillation column to produce a first residue comprising acetic acid, ethanol and water, and a first distillate comprising ethyl acetate and acetaldehyde; and separating the portion in the second distillation column The first residue produces a second residue comprising water and acetic acid and a second distillate comprising ethanol, wherein the second distillate comprises less than 1% by weight of diethyl acetal.

In still another embodiment, the present invention relates to a method for producing ethanol, which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form an alkanoic acid, water, acetaldehyde, ethanol, and a crude ethanol mixture of diethyl acetal; and separating the crude ethanol mixture in one or more columns to recover an ethanol product comprising less than 1% by weight of diethyl acetal, wherein at least one of the columns has at least 40 stages Stripping section.

In still another embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; and in the first distillation column Separating a portion of the crude ethanol mixture to produce a first residue comprising an alkanoic acid and a first distillate comprising ethanol and acetaldehyde; and separating the second distillation column having a stripping section comprising at least 40 stages The first distillate is portiond to produce a second residue comprising ethanol and a second distillate comprising acetaldehyde, wherein the second residue comprises less than 1% by weight diethyl acetal.

In still another embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; separating in a first distillation column Part of the crude mixture of ethanol to produce a first residue comprising an alkanoic acid and a first distillate comprising ethanol, water, ethyl acetate and acetaldehyde; and a second distillation having a stripping section comprising at least 40 stages Separating a portion of the first distillate from the column to produce a a second residue of alcohol and water and a second distillate comprising ethyl acetate and acetaldehyde; and separating a second portion of the second residue in the third distillation column to produce a third residue comprising water And a third distillate comprising ethanol, wherein the third distillate comprises less than 1% by weight of diethyl acetal.

In still another embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; separating in a first distillation column Part of the crude mixture of ethanol to produce a first residue comprising a majority of water fed to the distillation column and a first distillate comprising ethanol, acetaldehyde and water; moving from the first distillate Separating water to produce an ethanol mixture stream; and separating a portion of the ethanol mixture stream in a second distillation column having a stripping section of at least 40 stages to produce a second residue comprising ethanol and a second stream comprising acetaldehyde The product wherein the second residue comprises less than 1% by weight of diethyl acetal.

In still another embodiment, the invention relates to a process for the manufacture of ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; Separating a portion of the crude ethanol mixture in a first distillation column of the stripping section to produce a first residue comprising ethanol and water and a first distillate comprising ethyl acetate and acetaldehyde; and in the second distillation column A portion of the first residue is separated to produce a second residue comprising water and a second distillate comprising ethanol, wherein the second distillate comprises less than 1% by weight diethyl acetal.

In still another embodiment, the present invention relates to a process for producing ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; separating in a first distillation column Part of the crude mixture of ethanol to produce a first residue comprising an alkanoic acid and a first distillate comprising ethanol, water, ethyl acetate and acetaldehyde; and a second distillation having a stripping section comprising at least 40 stages Separating a portion of the first distillate from the column to produce a second residue comprising ethanol and water and a second distillate comprising ethyl acetate and acetaldehyde; and separating the portion in the third distillation column The second residue produces a third residue comprising water and a third distillate comprising ethanol, wherein the third distillate comprises less than 1% by weight of diethyl acetal.

In still another specific embodiment, the present invention relates to a method of producing ethanol, which comprises Hydrogenating the alkanoic acid and/or its ester in the presence of a catalyst to form a crude mixture of ethanol; separating a portion of the crude ethanol mixture in the first distillation column to produce a feed comprising the majority of the distillation column a first residue of water and a first distillate comprising ethanol, acetaldehyde and water; removing water from the first distillate to produce a stream of ethanol mixture; and having a stripping section comprising at least 40 stages Separating a portion of the ethanol mixture stream from the second distillation column to produce a second residue comprising ethanol and a second distillate comprising acetaldehyde, wherein the second distillate comprises less than 1% by weight of diethyl Acetal.

In still another embodiment, the invention relates to a process for the manufacture of ethanol which comprises hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form a crude mixture of ethanol; Separating a portion of the crude ethanol mixture in a first distillation column of the stripping section to produce a first residue comprising ethanol and water and a first distillate comprising ethyl acetate and acetaldehyde; and in the second distillation column A portion of the first residue is separated to produce a second residue comprising water and a second distillate comprising ethanol, wherein the second distillate comprises less than 1% by weight diethyl acetal.

introduction

The present invention relates to a process for recovering ethanol from a crude mixture obtained by hydrogenating an alkanoic acid and/or its ester. During hydrogenation, several other organics may be formed with the ethanol in the crude mixture. These organics may also form during ethanol recovery and thus further reduce ethanol yield. In particular, aldehydes may be present in the crude mixture and acetalization of the aldehyde may result in acetals. When acetic acid is hydrogenated to ethanol, acetaldehyde may form as an intermediate. The equilibrium reaction of acetaldehyde (AcH) scetalization to form diethyl acetal (DEA) is as follows:

Since the concentration of ethanol in the crude mixture is relatively large compared to the concentration of acetaldehyde and/or diethyl acetal, the equilibrium tends to be acetalized. Furthermore, the reaction mixture may contain acetic acid and The acetal reaction can be further catalyzed in the presence of a mineral acid or a carboxylic acid. Therefore, the concentration of diethyl acetal may increase during the recovery of ethanol from the crude mixture. Diethyl acetal may be difficult to remove from ethanol because diethyl acetal is a high boiling organic substance relative to other organics formed during hydrogenation. Ethanol may be required to reduce the concentration of diethyl acetal in further applications as industrial grade ethanol and fuel grade ethanol, such as less than 1% by weight of diethyl acetal, less than 0.1% by weight of diethyl acetal or less. 0.01% by weight of diethyl acetal. When expressed as a range, the diethyl acetal may be from 0.0001 to 1% by weight, such as from 0.0001 to 0.1% by weight, or from 0.0001 to 0.01% by weight.

The present invention provides a process for reducing the concentration of acetal during ethanol recovery. Without being bound by theory, the present invention may enhance this equilibrium to tend to hydrolyze or reduce the acetalization towards acetal formation. In one embodiment, from 10 to 75% of the acetal may be decomposed in the column under pressure, such as from 15 to 60%, or more preferably from 20 to 40%.

In a specific example, the concentration of the acetal can be reduced by separating the crude mixture or its derivative stream by a distillation column operated under pressure. From the separation of ethanol from the crude mixture, there may be several distillation columns and the acetal concentration may be reduced by operating at least one of several distillation columns under pressure. The pressurization in the column reduces the concentration of acetal. This pressure can be increased by the concentration of acetal fed into the column. In one embodiment, the pressurization is greater than atmospheric pressure, such as from 101 kPa to 5,000 kPa, such as from 120 kPa to 4,000 kPa, or from 150 kPa to 3,000 kPa.

In some embodiments, one of the columns in the separation can be operated at a higher pressure than the other columns to further enhance the hydrolysis of the acetal in the column.

When recovering ethanol from the crude mixture, the acetal can be formed in any column, so it may be necessary to operate the last column in the separation process under boost. The remaining columns can be operated at any desired pressure to further separate the ethanol. For example, low pressure or vacuum conditions can enhance the separation of ethyl acetate and ethanol.

In another embodiment, the separation of ethanol from the crude mixture or its derivative stream in a distillation column having a stripping section of at least 40 stages, such as at least 50 stages or at least 60 stages, reduces the acetal concentration. Preferably, the ethanol is recovered from the residue of the column. The distillation column having this stripping section can also be operated under pressure to further reduce the acetal concentration.

In addition to diethyl acetal, specific examples of the invention may also be used to hydrolyze other acetals. Classes such as these acetals are selected from the group consisting of ethyl propyl acetal, ethyl butyl acetal, dimethyl acetal, methyl ethyl acetal and their hemiacetals and mixtures thereof. Group of.

The process of the present invention can be used with any hydrogenation process used to make ethanol. Materials, catalysts, reaction conditions, and separation processes that can be used in the hydrogenation of acetic acid are detailed below.

The feedstock, acetic acid and hydrogen fed to the reactor used in the process of the invention may be derived from any suitable source, including natural gas, petroleum, coal, biomass materials and the like. For example, acetic acid can be produced by methanol carbonylation, acetaldehyde oxidation, ethylene oxidation, oxidative fermentation, and anaerobic fermentation. Methanol carbonylation processes suitable for the manufacture of acetic acid are described in U.S. Patent Nos. 7,208,624, 7,115, 772, 7,005, 541, 6, 657, 078, 6, 627, 770, 6, 143, 930, 5, 599, 976, 5, 144, 068, 5, 026, 908, 5, 001, 259, and 4, 994, 608, the entire disclosures of each of which are incorporated herein by reference. Optionally, ethanol production can be integrated with the methanol carbonylation process.

As oil and natural gas prices become expensive or cheaper, methods for producing acetic acid and intermediates such as methanol and carbon monoxide from other carbon sources are gaining attention. In particular, when petroleum is relatively expensive, it would be advantageous to produce acetic acid from a synthesis gas ("synthesis gas") derived from other available carbon sources. A method for retrofitting a methanol plant for the manufacture of acetic acid is taught, for example, in U.S. Patent No. 6,232,352, the entire disclosure of which is incorporated herein by reference. By modifying the methanol plant, the associated significant cost and associated carbon monoxide for the new acetic acid plant can be significantly reduced or substantially eliminated. All or part of the synthesis gas system is derived from a methanol synthesis loop and is supplied to a separator unit to recover carbon monoxide, which is then used to make acetic acid. In a similar manner, hydrogen from the hydrogenation step can be supplied from the syngas.

In some embodiments, some or all of the starting materials for the acetic acid hydrogenation process may be derived in part or in whole from the syngas. For example, acetic acid can be formed from methanol and carbon monoxide, both derived from syngas. The syngas can be formed by partial oxidation reforming or steam reforming, and carbon monoxide can be separated from the syngas. Similarly, the hydrogen used in the step of hydrogenating acetic acid to form a crude mixture of ethanol can be separated from the syngas. This syngas can in turn be derived from a variety of carbon sources. The carbon source may, for example, be selected from the group consisting of natural gas, crude oil, petroleum, coal, biomass materials, or combinations thereof. Syngas or hydrogen can also be obtained from biologically derived methane gases such as those produced by waste burial or agricultural waste. Methane gas.

In another embodiment, the acetic acid used in the hydrogenation step can be formed by fermentation from a biomass material. The fermentation process preferably utilizes a homoacetogenic process or a homoacetogenic microorganism to ferment the sugar to acetic acid and produce a very small amount, if any, of carbon dioxide as a by-product. The carbon efficiency of the fermentation process is preferably greater than 70%, greater than 80% or greater than 90% compared to conventional yeast processes which generally have a carbon efficiency of about 67%. As the case may be, the microorganism used in the fermentation process is a genus belonging to the genus Clostridium, Lactobacillus, Moorella, Thermoanaerobacter. a group consisting of Propionibacterium, Propionispera, Anaerobiospirillum, and Bacteriodes, and especially the species selected from Clostridium formicoaceticum, Clostridium butyricum, Moorella thermoacetica, Thermoanaerobacter kivui, Lactobacillus delbrueckii, Propionibacterium Propionibacterium acidipropionici), Propionispera arboris, Anaerobiospirillum succinicproducens, Bacteriodes amylophilus, and Bacteroides ruminicola. Optionally, in the present process, the unfermented residue of all or part of the autologous material (e.g., lignan) can be gasified to form hydrogen which can be used in the hydrogenation step of the present invention. The exemplified fermentation process for the formation of acetic acid is described in U.S. Patent Nos. 6,509,180, 6,927,048, 7,074,603, 7,507,562, 7, 351, 559, 7, 601, 865, 7, 682, 812, and 7, 888, 082, incorporated herein by reference. See also U.S. Patent Publication Nos. 2008/0193989 and 2009/0281354, the entire contents of each of which are hereby incorporated by reference.

Examples of biomass materials include, but are not limited to, agricultural waste, forest products, turf and other cellulosic materials, wood residues in lumber yards, cork sheets, hardwood chips, branches, trunks, leaves, bark, wood chips, substandard pulp, Corn, corn stalk, wheat crumb, rice crumb, bagasse, switchgrass, miscanthus, animal waste, municipal waste, municipal sewage, commercial waste, grape pumice, apricot kernel shell, large walnut shell, coconut shell, coffee Slag, grass, dry Grass, wood, cardboard, paper, plastic and cloth. See, for example, U.S. Patent No. 7,884,253, the disclosure of which is incorporated herein by reference in its entirety. Other sources of biomass material are straw black liquor, a thick black liquid that is a by-product of the kraft pulp process used to convert wood into pulp, which is then dried for papermaking. The straw black liquor is an aqueous solution of lignin residues, hemicellulose and inorganic chemicals.

U.S. Patent Re-issued Patent No. RE35,377, which is incorporated herein by reference in its entirety, is incorporated herein by reference. The process involves hydrogenating a solid and/or liquid carbonaceous material to obtain a process gas that is cracked with other natural gas to form a syngas. The syngas is converted to methanol which can be further carbonylated to acetic acid. This method also produces hydrogen which can be used in the above invention. U.S. Patent No. 5,821,111 discloses a process for the conversion of waste biomass material into a synthesis gas via gasification, and a method for producing a hydrogen-containing gas composition such as a synthesis gas comprising hydrogen and carbon monoxide is disclosed in U.S. Patent No. 6,685,754, incorporated herein by reference. This article is for reference.

The acetic acid fed to the hydrogenation reactor also includes other carboxylic acids and anhydrides as well as aldehydes and/or ketones such as acetaldehyde and acetone. Preferably, the suitable acetic acid feed stream comprises one or more compounds selected from the group consisting of acetic acid, acetic anhydride, acetaldehyde, ethyl acetate, and mixtures thereof. These other compounds may also be hydrogenated in the process of the invention. In some embodiments, the presence of a carboxylic acid such as propionic acid or an anhydride thereof may be advantageous for the manufacture of propanol. Water can also be present in the acetic acid feed.

Alternatively, the acetic acid in the vapor state can be obtained directly from the crude product in a flash vessel of the methanol carbonylation unit as described in U.S. Patent No. 6,657,078, the entire disclosure of which is incorporated herein by reference. The crude steam product can, for example, be fed directly into the hydrogenation reactor without the need to condense or remove water from the acetic acid and light hydrocarbons, thereby saving overall processing costs.

The acetic acid can be vaporized at the reaction temperature, and then the vaporized acetic acid can be fed together with hydrogen in an undiluted state or with hydrogen diluted with a relatively inert carrier such as nitrogen, argon, helium, carbon dioxide or the like. The reaction operation in the vapor phase of the system, the temperature should be controlled so as not to fall below the dew point of the acetic acid. In one embodiment, the acetic acid can be vaporized at a specific pressure at the boiling point of acetic acid, and then the vaporized acetic acid is further heated to the reactor inlet temperature. In another embodiment, the acetic acid is mixed with other gases prior to vaporization, and then the mixed steam is heated. To the reactor inlet temperature. Preferably, the acetic acid is transferred to the vapor state by passing hydrogen and/or a recycle gas through the acetic acid at a temperature of 125 ° C or less, and then the combined gas stream is heated to the reactor inlet temperature.

The reactors in some embodiments may include various configurations using fixed bed reactors or fluid bed reactors. In many embodiments of the invention, an "adiabatic" reactor can be used, i.e., there is little or no need to pass an internal conduit into the reaction zone to add or remove heat. In other embodiments, a radial flow reactor or groups of reactors may be utilized, or a series of reactors in series may be utilized, with or without heat exchange, quenching or introduction of additional feed materials. Alternatively, a shell type and tubular reactor equipped with a heat transfer medium can be used. In many instances, the reaction zone can be housed in a single vessel or housed in a series of vessel vessels with heat exchanger intervention therebetween.

In a preferred embodiment, a catalyst is used in a fixed bed reactor, such as a straight tube or a tubular reactor, where the generally gaseous reactant passes over or within the catalyst. Other reactors such as fluid or ebullient bed reactors can be used. In some instances, the hydrogenation catalyst can be combined with an inert material to adjust the pressure drop of the reactant stream through the catalyst bed and the contact time of the reactant compound with the catalyst particles.

The hydrogenation reaction can be carried out in the liquid phase or in the vapor phase. Preferably, the reaction is carried out in the vapor phase under the following conditions. The reaction temperature may range from 125 ° C to 350 ° C, such as from 200 ° C to 325 ° C, from 225 ° C to 300 ° C, or from 250 ° C to 300 ° C. The pressure can range from 10 kPa to 3000 kPa, such as from 50 kPa to 2300 kPa, or from 100 kPa to 1500 kPa. The reaction may be greater than 500 hr ^-1 (h ^-1), 1000hr ^-1, for example, greater than, greater than, or even greater than 2500 hr ^-1 gas hourly space velocity of 5000 hr ^-1 (a GHSV) fed into the reactor. When expressed in a range of GHSV may range from 50,000hr ^-1 to 50hr ^-1, the self-500hr ^-1 to 30,000hr ^-1, from 1000hr ^-1 to 10,000hr ^-1, or from 1000hr ^-1 to 6500hr ^-1 .

The hydrogenation reaction can be carried out at a pressure just sufficient to overcome the pressure drop across the catalytic bed at the selected GHSV, but does not preclude the use of high pressures, it being understood that a relatively high pressure velocity through the reaction bed may experience high space-time velocities, Such as 5000hr ^-1 or 6,500hr ^-1 .

Although the reaction consumes two moles of hydrogen per mole of acetic acid to produce one mole of ethanol, the actual molar ratio of hydrogen to acetic acid in the feed stream can vary from about 100:1 to 1:100, such as from 50. :1 to 1:50, from 20:1 to 1:2, or from 12:1 to 1:1. Preferably, the molar ratio of hydrogen to acetic acid is greater than 2:1, such as greater than 4:1 or greater than 8:1.

Contact or residence times can also vary widely, depending on various variables such as amount of acetic acid, catalyst, reactor, temperature and pressure. When a catalyst system is used instead of a fixed bed, the typical contact time ranges from a few milliseconds to over several hours, and at least the preferred contact time for the vapor phase reaction is from 0.1 to 100 seconds, for example from 0.3 to 80 seconds or from 0.4 to 30 seconds.

The hydrogenation of acetic acid to form ethanol is preferably carried out in the presence of a hydrogenation catalyst. Suitable hydrogenation catalysts include the first metal and optionally one or more second metals, third metals or any number of other metals, and are optionally supported on the catalyst support. The first metal and optionally the second metal and the third metal may be selected from Group IB, IIB, IIIB, IVB, VB, VIB, VIIB, Group VIII transition metals, lanthanide metals, lanthanide metals or selected from Group IIIA Any metal of the IVA, VA and VIA families. Preferred metal compositions for some of the exemplified catalyst compositions include platinum/tin, platinum/rhodium, platinum/rhodium, palladium/ruthenium, palladium/ruthenium, cobalt/palladium, cobalt/platinum, cobalt/chromium, cobalt/ruthenium. , cobalt/tin, silver/palladium, copper/palladium, copper/zinc, nickel/palladium, gold/palladium, rhodium/iridium, or rhodium/iron. The catalysts listed are further described in U.S. Patent No. 7,608,744 and U.S. Patent Publication No. 2010/002999, the entire disclosure of which is incorporated herein by reference. In another embodiment, the catalyst comprises a Co/Mo/S catalyst of the type described in U.S. Patent Publication No. 2009/0069609 A1, which is incorporated herein by reference in its entirety.

In one embodiment, the catalyst comprises a first metal selected from the group consisting of copper, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, titanium, zinc, chromium, lanthanum, molybdenum, and tungsten. group. Preferably, the first metal is selected from the group consisting of platinum, palladium, cobalt, nickel and ruthenium. More preferably, the first metal is selected from the group consisting of platinum and palladium. In the specific example of the invention wherein the first metal comprises platinum, preferably the catalyst comprises less than 5% by weight of platinum, such as less than 3% by weight or less than 1% by weight, due to the higher platinum The reason for business needs.

As noted above, in some embodiments, the catalyst further includes a second metal that generally functions as a promoter. If a second metal is present, it is preferably selected from the group consisting of copper, molybdenum, tin, chromium, iron, cobalt, vanadium, tungsten, palladium, platinum, rhodium, ruthenium, manganese, osmium, iridium, gold, and nickel. Group. More preferably, the second metal is selected from the group consisting of copper, tin, cobalt, ruthenium and nickel. More preferably, the second metal is selected from the group consisting of tin and antimony.

In some specific examples in which the catalyst comprises two or more metals such as a first metal and a second metal, the first metal is present in the catalyst in an amount of from 0.1 to 10% by weight, such as from 0.1 to 5% by weight, or From 0.1 to 3% by weight. The second metal is preferably present in an amount of from 0.1 to 20% by weight, such as from 0.1 to 10% by weight, or from 0.1 to 5% by weight. The two or more metals may be alloyed with one another or may comprise a non-alloyed molten metal or mixture based on a catalyst comprising two or more metals.

The preferred metal ratio may depend on the metal used in the catalyst. In some specific examples, the molar ratio of the first metal to the second metal is from 10:1 to 1:10, such as from 4:1 to 1:4, or from 2:1 to 1:2, from 1.5: 1 to 1:1.5, or from 1.1:1 to 1:1.1.

The catalyst may also include a third metal selected from any of the metals listed in the first metal or the second metal, as long as the third metal is different from the first metal and the second metal. Preferably, the third metal is selected from the group consisting of cobalt, palladium, rhodium, copper, zinc, platinum, tin and antimony. More preferably, the third metal is selected from the group consisting of cobalt, palladium, and rhodium. When a third metal is present, the total amount of the third metal is preferably from 0.05 to 4% by weight, such as from 0.1 to 3% by weight, or from 0.1 to 2% by weight.

In addition to one or more metals, in some embodiments of the invention, the catalyst further includes a support or a modified support. As used herein, "modified carrier" means a support comprising a support material and a support modifier for adjusting the acidity of the support material.

The total weight of the support or the modified support, based on the total weight of the catalyst, is preferably from 75 to 99.9% by weight, such as from 78 to 97% by weight, or from 80 to 95% by weight. In a preferred embodiment using a modified support, the support modifier is present in an amount of from 0.1 to 50% by weight based on the total weight of the catalyst, such as from 0.2 to 25% by weight, from 0.5 to 15% by weight, or from 1 to 8 wt%. The metal of the catalyst can be dispersed throughout the support, layered throughout the support, coated on the surface of the support (such as an eggshell) or applied to the surface of the support.

As will be appreciated by those skilled in the art, the support material is selected such that the catalyst system is suitably activated, selective, and robust under the process conditions used to form the ethanol.

Suitable support materials may include, for example, a support based on a metal oxide-based support or ceramic. Preferred supports include tantalum supports such as cerium oxide, cerium oxide/alumina, Group IIA cerates such as calcium metasilicate, pyrolytic cerium oxide, high purity cerium oxide and mixtures thereof. Other burden The body may include, but is not limited to, iron oxide, aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide, carbon, graphite, high surface area graphitized carbon, activated carbon, and mixtures thereof.

As described, the catalyst support can be modified with a bulk modifier. In some specific examples, the bulk modifier may be an acidic modifier that increases the acidity of the catalyst. Suitable acidic support modifiers may be selected from oxides of Group IVB metals, oxides of Group VB metals, oxides of Group VIB metals, oxides of VIIB metals, oxides of Group VIIIB metals, aluminum oxides and mixtures thereof The group formed. The acidic carrier modifier includes those selected from the group consisting of TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , P ₂ O ₅ , and Sb ₂ O ₃ . Group. The preferred acidic agent comprises modifying carrier substance selected from the group consisting of the _{TiO 2, ZrO 2, Nb2O 5} , Ta ₂ O ₅ and the group Al ₂ O ₃ consisting of. The acidic support modifier may also include those selected from the group consisting of WO ₃ , MoO ₃ , Fe ₂ O ₃ , Cr ₂ O ₃ , V ₂ O ₅ , MnO ₂ , CuO, Co ₂ O ₃ , and Bi ₂ O _{3 .} The group formed.

In another embodiment, the bulk modifier can be an alkaline modifier having low or no volatility. The alkaline modifier may, for example, be selected from (i) an alkaline earth metal oxide, (ii) an alkali metal oxide, (iii) an alkaline earth metal metasilicate, (iv) an alkali metal metasilicate, (v) IIB. Groups of metal oxides, (vi) Group IIB metal metasilicates, (vii) Group IIIB metal oxides, (viii) Group IIIB metal metasilicates, and mixtures thereof. In addition to oxides and metasilicates, other types of modifiers may be used including nitrates, nitrites, acetates, and lactates. Preferably, the support modifier is selected from the group consisting of oxides and metasilicates of any of sodium, potassium, magnesium, calcium, strontium, barium, and zinc, and any of the foregoing. More preferably, the alkaline modifier is calcium citrate and even more preferably calcium metasilicate (CaSiO ₃ ). If the alkaline support modifier comprises calcium metasilicate, it is preferred that at least a portion of the calcium metasilicate is crystalline.

A preferred cerium oxide support material is the SS61138 high surface area (HSA) cerium oxide catalyst carrier available from Saint-Gobain NorPro. Saint-Gobain NorPro SS61138 cerium oxide exhibits the following properties: contains about 95% by weight of high surface area cerium oxide; surface area of about 250 m ² /g; median pore diameter of about 12 nm; average pore volume measured by mercury intrusion porosimetry About 1.0 cm ³ /g; and a packing density of about 0.352 g/cm ³ (22 lb/ft ³ ).

A preferred cerium oxide/alumina support material is KA-160 cerium oxide sphere obtained from Süd Chemie having a nominal diameter of about 5 nm, a density of about 0.562 g/ml, and an adsorption ratio of about 0.583 g H ₂ O/g. The surface area is about 160 to 175 m ² /g, and the pore volume is about 0.68 ml/g.

The catalyst composition suitable for use in the present invention is preferably formed by metal impregnation of the modified support, but other processes such as chemical vapor deposition may also be used. The saturation technique is described in the aforementioned U.S. Patent Nos. 7,608,744 and 7,863,489, and U.S. Patent Publication No. 2010/0197485, the entire disclosure of which is incorporated herein by reference.

In particular, the hydrogenation of acetic acid achieves an advantageous conversion of acetic acid and an advantageous selectivity and yield of ethanol. For the purposes of the present invention, the term "conversion" means the amount of acetic acid converted to a compound other than acetic acid in the feed. The conversion is expressed as a percentage of acetic acid in the feed. As shown, the conversion rate of the first specific example is from 40% to 70%, and the conversion rate of the second specific example is more than 85%.

The selectivity is expressed as the percentage of moles based on converted acetic acid. It will be appreciated that each compound converted from acetic acid has an independent selectivity and that the selectivity and conversion are also independent of each other. For example, if 60 mole % of converted acetic acid is converted to ethanol, the selectivity of the ethanol is said to be 60%. Preferably, the catalyst selectivity for ethoxylates is at least 60%, such as at least 70%, or at least 80%. The term "ethoxylate" as used herein particularly denotes the compounds ethanol, acetaldehyde and ethyl acetate. Preferably, the selectivity to ethanol in the reactor is at least 80%, such as at least 85% or at least 88%. Preferred embodiments of the hydrogenation process also have low selectivity for undesirable products such as methane, ethane and carbon dioxide. The selectivity for such undesired products is preferably less than 4%, such as less than 2% or less than 1%. More preferably, the undesired products are present in a non-detectable amount. The formation of alkanes may be lower and ideally less than 2%, less than 1% or less than 0.5% of the acetic acid will be converted to alkanes, while the alkanes have only polar low value.

As used herein, the term "yield" means based on the kilogram of catalyst used per hour being more than the grams of a particular product formed during hydrogenation, such as ethanol. A preferred yield is at least 400 grams of ethanol per kilogram of catalyst per hour or at least 600 grams of ethanol per kilogram of catalyst per hour. When expressed in terms of range, the yield is preferably from 100 to 3,000 grams of ethanol per kilogram of catalyst per hour, such as from 400 to 2,500 grams of ethanol per kilogram of catalyst per hour, or from 600 per kilogram of catalyst per hour. Up to 2,000 grams of ethanol.

Operation under the conditions of the present invention can produce an ethanol production of at least 0.1 ton per hour, such as at least 1 ton of ethanol per hour, at least 5 tons of ethanol per hour, or at least 10 tons of ethanol per hour. Larger ethanol manufacturing industry scale, depending on size, should typically produce at least 1 ton of ethanol per hour, such as at least 15 tons per hour, or at least 30 tons per hour. In terms of ranges, the process of the present invention can produce from 0.1 to 160 tons of ethanol per hour for larger ethanol manufacturing industries, such as 15 to 160 tons of ethanol per hour, or 30 to 80 tons of ethanol per hour. Due to the economic scale, it is generally impossible to achieve a scale that can be achieved by using a specific example of the present invention in a single plant to perform ethanol production by fermentation.

In various embodiments of the invention, the crude ethanol mixture produced by the reactor typically comprises acetic acid, ethanol, and water prior to any subsequent processing, such as purification and separation. The term "alcohol crude mixture" as used herein means any composition comprising from 5 to 70% by weight of ethanol and from 5 to 40% by weight of water. An exemplary composition range for the crude ethanol mixture is shown in Table 1. The "others" indicated in Table 1 may include, for example, esters, ethers, aldehydes, ketones, alkanes, and carbon dioxide.

In one embodiment, the crude ethanol mixture can include less than 20% by weight of acetic acid, such as less than 15% by weight, less than 10% by weight, or less than 5% by weight. In a specific example having a lower amount of acetic acid, the acetic acid conversion is preferably greater than 75%, such as greater than 85% or greater than 90%. In addition, the selectivity to ethanol is also preferably higher, and preferably greater than 75%, such as greater than 85% or greater than 90%.

Ethanol separation

The ethanol produced can be recovered using several different techniques. In Figure 1, the separation of the crude ethanol mixture used four columns. In one embodiment, the first column 120, the second column 123, and/or the third column 128 can be operated under boost. In one embodiment, the second column 123 can have a stripping section that includes at least 40 steps, such as at least 50 steps or at least 60 steps.

In Figure 2, the crude ethanol mixture was separated by intervening water separation in two columns. Any of the towers in Figure 2 can be operated under boost. Fig. 3 is a separation similar to that of Fig. 2, but the liquid stream containing ethanol is used in parallel in a column operated under vacuum conditions and in a column for pressurized operation. Figure 4 uses a low pressure column in series, followed by a column of pressurized operation to separate the liquid stream containing ethanol. Figure 5 is used in series to separate the distillate in a column of pressurized operation followed by separation of the distillate in a lower pressure column to separate the liquid stream containing ethanol. In Figures 4 and 5, the residue of the lower pressure column can be combined with the residue of the column operated under pressure to form an ethanol product.

In Figure 6, the separation of the crude ethanol mixture uses two columns. Any of the columns of Figure 6 can be operated under boost, but it is preferred to operate the first column 170 at high pressure.

Other separation systems can also be used with specific examples of the invention. For convenience, the columns in each of the illustrated separation processes can be represented as a first column, a second column, a third column, and the like.

In each of the figures, hydrogenation system 100 includes a reaction zone 101 and a separation zone 102. Hydrogen and acetic acid are fed to vaporizer 106 via line 104, line 105, respectively, and a vapor feed stream is produced in line 107, which is directed to reactor 103. In one embodiment, the line 104 and the line 105 can be combined and combined with the feed to the vaporizer 106. The vapor feed stream temperature in line 107 is preferably from 100 ° C to 350 ° C, such as from 120 ° C to 310 ° C or from 150 ° C to 300 ° C. Any feed that is not steamed is removed from the vaporizer 106 and can be recycled or discarded. Further, although the display line 107 is introduced to the top of the reactor 103, the line 107 can be introduced into the side, upper or bottom of the reactor 103.

Reactor 103 contains a catalyst for the carboxylic acid, preferably acetic acid, to hydrogenate to ethanol. In one embodiment, one or more guard beds (not shown) may be used upstream of the reactor (as appropriate upstream of vaporizer 106) to avoid contact of the catalyst with the feed or return/circulation flow. Poisons contained in or undesired impurities. This guard bed can be used in a vapor or liquid stream. Suitable protective bed materials may include, for example, carbon, cerium oxide, Alumina, ceramic or resin. In a certain state, the guard bed media is functionalized, such as by silver, to capture a particular species such as sulfur or halogen. During the hydrogenation process, a crude ethanol mixture stream is withdrawn (preferably continuously withdrawn) from reactor 103 via line 109.

The crude ethanol mixture stream of line 109 can be condensed and fed to separator 110, which in turn provides a vapor stream 111 and a liquid stream 112. In one embodiment, the separator 110 can include a flasher or a knockout pot. The separator 110 can be operated at a temperature from 20 ° C to 250 ° C, such as from 30 ° C to 225 ° C or from 60 ° C to 200 ° C. The pressure of separator 110 can range from 50 kPa to 2000 kPa, such as from 75 kPa to 1500 kPa or from 100 kPa to 1000 kPa. Optionally, the crude ethanol mixture stream in line 109 can be passed through one or more membranes to separate hydrogen and/or other non-condensable gases.

The vapor stream 111 exiting the separator 110 can include hydrogen and hydrocarbons and can be purged and/or returned to the reaction zone 101 by blowing. When returning to reaction zone 101, steam stream 110 is combined with hydrogen feed 104 and co-fed into vaporizer 106. In some embodiments, the returning vapor stream 111 can be compressed prior to being combined with the hydrogen feed 104.

In Figure 1, liquid stream 112 from separator 110 is withdrawn and pumped into the side of first column 120, also referred to as an "acid separation column." In one embodiment, the contents of liquid stream 112 are substantially similar to the crude mixture of ethanol obtained from the reactor, except that hydrogen, carbon dioxide, methane, and/or ethane have been removed from the composition, and the separator 110 is removed. And was removed. Accordingly, liquid stream 112 can also be referred to as a crude mixture of ethanol. Exemplary components of liquid stream 112 are found in Table 2 below. It should be understood that liquid stream 112 may contain other components not listed in Table 2.

The amount indicated by less than (<) in the table of the entire specification is preferably absent or, if present, in a trace amount or in an amount of more than 0.0001% by weight.

The "other esters" in Table 2 may include, but are not limited to, ethyl propionate, methyl acetate, isopropyl acetate, n-propyl acetate, n-butyl acetate or a mixture thereof. The "other ethers" in Table 2 may include, but are not limited to, diethyl ether, methyl ethyl ether, isobutyl ethyl ether or a mixture thereof. The "other alcohols" in Table 2 may include, but are not limited to, methanol, isopropanol, n-propanol, n-butanol or a mixture thereof. In one embodiment, liquid stream 112 can include propanol such as isopropanol and/or n-propanol in an amount from 0.001 to 0.1% by weight, from 0.001 to 0.05% by weight, or from 0.001 to 0.03% by weight. It is to be understood that these other components can be carried by any of the distillate or residue streams described herein and will not be described herein unless otherwise indicated.

Optionally, the crude ethanol mixture in line 109 or liquid stream 112 can be further fed to an esterification reactor, a hydrogenolysis reactor, or a combination thereof. The esterification reactor can be used to consume residual acetic acid present in the crude ethanol mixture to further reduce the amount of acetic acid that must be removed. Hydrogenolysis can be used to convert the ethyl acetate in the crude ethanol mixture to ethanol.

In the specific example shown in Fig. 1, the line 112 is introduced into the lower portion of the first column 120, at the lower half or at the lower third. In the first column 120, acetic acid, a portion of the water, and other heavy components if present are removed from the composition of line 121 and are withdrawn as a residue, and The good ones are continuously drawn out. Some or all of this residue may be returned via line 121 and/or recycled back to reaction zone 101. Recirculating the acetic acid in line 121 to vaporizer 106 reduces the amount of heavies that must be purged from vaporizer 106 by blowing. Reducing the amount of heavy material that needs to be purged can improve process efficiency while reducing by-products.

The first column 120 also forms an overhead which is withdrawn in line 122 and which can be condensed and refluxed, for example, at a ratio of from 10:1 to 1:10, such as from 3:1 to 1:3. Or reflux from 1:2 to 2:1. The distillate in line 122 consists essentially of ethanol and water, ethyl acetate, acetaldehyde, and/or diethyl acetal. For example, the distillate can include from 20 to 75% by weight ethanol and from 10 to 40% by weight ethanol. Preferably, the concentration of acetic acid in the distillate is less than 2% by weight, such as less than 1% by weight or less than 0.5% by weight.

In one embodiment, column 120 can be operated at a supercharge above atmospheric pressure to enhance acetal hydrolysis of feed column 120. When column 120 is operated under boost, the first distillate in line 121 may have a diethyl acetal concentration of less than 1% by weight, such as less than 0.1% by weight or less than 0.01% by weight.

When the other column purification section 102 of Figure 1 is operated under boost, the first column 120 can be operated at ambient pressure. In another embodiment, the pressure of the first column 120 can range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa. When the first column 120 is operated at standard atmospheric pressure, the temperature of the residue flowing out of the line 121 is preferably from 95 ° C to 120 ° C, such as from 110 ° C to 117 ° C or from 111 ° C to 115 ° C. The temperature of the distillate flowing out of line 122 is preferably from 70 ° C to 110 ° C, such as from 75 ° C to 95 ° C or from 80 ° C to 90 ° C.

In one embodiment, even if the second column 120 is not operated under boost, without being bound by theory, it is unexpectedly and unpredictably found that when any amount of acetal is detected in the feed, the shrinkage The aldehyde appears to decompose in the column such that there is little or even no detectable amount of acetal in the distillate and/or residue. Increasing the pressure of the first column 120 can in turn reduce the acetal concentration. In one embodiment, 10 to 75% of diethyl acetal may be decomposed in the first column 120, such as from 15 to 60% or more preferably from 20 to 40% diethyl acetal.

To further separate the distillate, line 122 is directed to second column 123, which is also referred to as a "light hydrocarbon column", preferably intermediate portion of introduction column 123. Preferably, the second column 123 is an extractive distillation column and an extractant is added thereto via lines 124 and/or 125. Extractive distillation is a process for separating boiling-point similar components such as azeotropes by distilling the feed in the presence of an extractant. Preferably, the extractant has a boiling point above the compound to be separated in the feed. In a preferred embodiment, the extractant primarily comprises water. As mentioned above, the first distillate fed to line 122 of second column 123 comprises ethanol, water and ethyl acetate. These compounds tend to form binary azeotropes and ternary azeotropes which reduce separation efficiency. As shown, in one embodiment, the extractant includes a third residue in line 124. Preferably, the third residue recycled in line 124 is fed at a feed point above the first distillate in line 122. In one embodiment, the recycled third residue in line 124 is fed near the top of second column 123, for example, above the feed of line 122 and below the return line of the condensate. In the plate column, the third residue in line 124 is continuously added near the top of second column 123, so that a measurable third residue is present in the liquid phase on all of the following trays. In another embodiment, the extractant is fed to the second column 123 via an external source of the process line 100. Preferably, the extractant comprises water for this purpose.

The water in the extractant is preferably at least 0.5:1, such as at least 1:1 or at least 3:1, for the molar amount of ethanol fed to the feed to the second column. When expressed in terms of range, the preferred molar ratio may range from 0.5:1 to 8:1, such as from 1:1 to 7:1, or from 2:1 to 6.5:1. Higher molar ratios can be used, but this reduces the return benefit of the additional ethyl acetate in the second distillate and reduces the ethanol concentration in the second column.

In a specific example, an additional extractant such as water from an external source, dimethyl hydrazine, glycerin, diethylene glycol, 1-naphthol, hydroquinone, N, N'-dimethyl may be added to the second column 123. Mercaptoamine, 1,4-butanediol; ethylene glycol-1,5-pentanediol; propylene glycol-tetraethylene glycol-polyethylene glycol; glycerol-propylene glycol-tetraethylene glycol-1,4- Butanediol, diethyl ether, methyl formate, cyclohexane, N,N'-dimethyl-1,3-propanediamine, N,N'-dimethylethylenediamine, diethylenetriamine, six Methylene diamine and 1,3-diaminopentane, alkylated thiophene, dodecane, tridecane, tetradecane and chlorinated paraffin. Some suitable extractants are described in U.S. Patent Nos. 4,379,028, 4,569, 726, 5, 993, 610, and 6, 375, 807, each incorporated herein by reference. This additional extractant can be combined with the recycled third residue in line 124 and fed together into the second column 123. The additional extractant may also be added to the second column 123, respectively. In one aspect, the extractant comprises an extractant, such as water derived from an external source via line 125, and all extractants are not derived from the third residue.

The second column 123 can be a plate column or a packed column. In one embodiment, the second column 123 is a plate column having a theoretical plate number of 5 to 120, such as from 15 to 80 theoretical plates or from 20 to 70 theoretical plates. In one embodiment, the stripping section of the second column 123 can have at least 40 steps, such as at least 50 steps or at least 60 steps. As described above, increasing the stripping section of the second column 123 enhances the hydrolysis of the diethyl acetal.

In Figure 1, the second column 123 can be operated under boost, such as greater than atmospheric pressure. In other specific examples, when one of the second column 123 or the third column 128 is operated under a boost, the pressure of the second column 123 may range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa. 375kPa.

The temperature of the second column 123 at atmospheric pressure is variable. In one embodiment, the temperature of the second residue flowing out of line 126 is preferably from 60 ° C to 90 ° C, such as from 70 ° C to 90 ° C or from 80 ° C to 90 ° C. The temperature of the second distillate flowing out of line 127 of second column 123 is preferably from 50 ° C to 90 ° C, such as from 60 ° C to 80 ° C or from 60 ° C to 70 ° C.

The second residue in line 126 includes ethanol and water. The second residue may comprise less than 3% by weight ethyl acetate, such as less than 1% by weight ethyl acetate or less than 0.5% by weight ethyl acetate. The second distillate in line 127 includes ethyl acetate, acetaldehyde, and/or diethyl acetal. Additionally, a small amount of ethanol may be present in the second distillate. The weight ratio of ethanol in the second residue to ethanol in the second distillate is at least 3:1, such as at least 6:1, at least 8:1, at least 10:1 or at least 15:1.

All or part of this third residue is recycled to the second column. In one embodiment, all of the third residue can be recycled until process 100 reaches a steady state and then a portion of the third residue is recycled and the remainder is purged from system 100. The composition of the second residue will tend to have a lower amount of ethanol than if the third residue were not recycled. When the third residue is recycled, the composition of the second residue comprises less than 30% by weight of ethanol, such as less than 20% by weight or less than 15% by weight. The major amount of the second residue preferably comprises water. Despite this effect, the extractive distillation step also advantageously reduces the amount of ethyl acetate sent to the third column, which is highly advantageous for the eventual formation of a high purity ethanol product.

As shown, the second residue from the second column 123 comprising ethanol and water is fed via line 126 into a third column 128, which is also referred to as a "product column." The second residue in the better line 126 is directed to the lower portion of the third column 128, such as the lower half or the lower third. The third column 128 recovers ethanol, which is preferably substantially pure relative to the organic impurity system and is non-common The boiling water content is used as the distillate in line 129. The distillate of the third column 128 is preferably refluxed as shown in Figure 1, for example from 1:10 to 10:1, such as from 1:3 to 3:1 or from 1:2 to 2:1. The reflux ratio is refluxed. Preferably, the third residue comprising primarily water in line 124 is returned to the second column 123 as an extractant as described above. In one embodiment, the third residue of the first portion of line 124 is recycled to the second column and the second portion is purged and removed from the system via line 130. In one embodiment, once the process reaches a steady state, the second portion of water to be purged is substantially similar to the amount of water formed in the acetic acid hydrogenation reaction. In one embodiment, a portion of the third residue can be used to hydrolyze any other stream, such as one or more streams including ethyl acetate. In one embodiment, the third residue in line 124 is withdrawn from third column 128 at a temperature that is higher than the operating temperature of second column 123. Preferably, the third residue in line 124 is integrated prior to returning to second column 123 to heat one or more other streams, or to be boiled again.

Although FIG. 1 shows that the third residue is directly recycled to the second column 123, it may be made by, for example, storing some or all of the third residue or treating the third residue in a tank (not shown). The third residue is returned indirectly to further separate any minor components such as aldehydes, high molecular weight alcohols or esters in one or more additional columns (not shown).

The third tower 128 is preferably a plate tower. In one embodiment, the third column 128 can be operated under boost to reduce the diethyl acetal concentration. When one of the first column 120 or the second column 123 is operated under boost, the third column can be operated from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa.

The temperature of the third distillate flowing out of line 129 at atmospheric pressure is preferably from 60 ° C to 110 ° C, such as from 70 ° C to 100 ° C or from 75 ° C to 95 ° C. The temperature of the third residue in line 124 is preferably from 70 ° C to 115 ° C, such as from 80 ° C to 110 ° C or from 85 ° C to 105 ° C.

Any compound carried by the distillation process from the feed or reaction crude product is typically retained in the third distillate in an amount less than 0.1% by weight of the total weight of the third distillate composition, such as less than 0.05% by weight Or less than 0.02% by weight. In one embodiment, one or more side streams may be removed from any of the columns in system 100. Preferably, the impurities are removed from the third column 128 using at least one side stream. The impurities may be purged and/or flowed within system 100. The ethanol product obtained from the third distillate in Figure 1 is shown in Table 3 below. Preferably, the ethanol product comprises less than 1% by weight of diethyl acetal, such as less than 0.5% by weight or less than 0.01% by weight of diethyl acetal.

The third distillate in line 129 can be further purified using one or more additional separation columns such as, for example, a distillation column, adsorption unit, membrane or molecular sieve to form an anhydrous ethanol product stream, i.e., "completed anhydrous ethanol." A suitable adsorption unit comprises a pressure swing adsorption unit and a thermal adsorption adsorption unit.

In Figure 1, any of the first column 120, the second column 123, or the third column 128 can be operated under pressure, such as from 101 kPa to 5,000 kPa, such as from 120 kPa to 4,000 kPa, or from 150 kPa to 3,000 kPa. Preferably, at least the second column 123 is operated under boost. In some embodiments, two of the towers can be operated under boost, such as second tower 123 and third tower 128.

Returning to the second column 123, the second distillate preferably ranges from 1:10 to 10:1 as in Figure 1, such as from 1:5 to 5:1 or from 1:3 to 3:1. The reflux ratio is refluxed. The second distillate in line 127 can be purged or recycled to the reaction zone by blowing. The second distillate in line 127 can be further processed in a fourth column 131, optionally selected, which is referred to as an "acetaldehyde removal column." In a fourth column 131, optionally selected, the second distillate is separated into a fourth distillate comprising acetaldehyde in line 132 and a fourth residue comprising ethyl acetate in line 133. The fourth distillate is preferably refluxed from 1:20 to 20:1, such as from 1:15 to 15:1 or from 1:10 to 10:1, and a portion of the fourth distillate Return to the reaction zone 101. For example, the fourth distillate can be combined with the acetic acid feed, added to the vaporizer 106, or added directly to the reactor 103. The fourth distillate is preferably fed to the vaporizer 106 in conjunction with the acetic acid of the feed line 105. Without wishing to be bound by theory, since acetaldehyde can be hydrogenated to form ethanol, recycling of the acetaldehyde-containing stream to the reaction zone will increase ethanol yield and reduce by-product and waste generation. In another embodiment, acetaldehyde can be collected and utilized, with or without further purification, to produce useful products including, but not limited to, n-butanol, 1,3-butanediol, and/or crotonaldehyde. And its derivatives.

The fourth residue of the fourth column 131, optionally selected, may be purged via line 133. The fourth residue mainly comprises ethyl acetate and ethanol, which may be suitable as a solvent mixture or for the manufacture of esters. In a preferred embodiment, acetaldehyde is removed from the second distillate in fourth column 131 such that an undetectable amount of acetaldehyde is present in the residue of column 131.

The fourth tower 131 selected as the case may be preferably a plate tower as described above, and preferably Operates above atmospheric pressure. In one embodiment, the pressure is from 120 kPa to 5,000 kPa, such as from 200 kPa to 4,500 kPa, or from 400 kPa to 3,000 kPa. In a preferred embodiment, the fourth column 131 can be operated at a pressure above the pressure of the other columns. Although the hydrolysis of the acetal may be promoted under the pressurization in the fourth column 131 as the case may be, since the fourth column 131 which is not selected by the self-viewing state recovers the ethanol, the increase may be the diethyl condensation in the ethanol product. The aldehyde concentration has little effect.

The temperature of the fourth distillate flowing out of line 132 is preferably from 60 ° C to 110 ° C, such as from 70 ° C to 100 ° C or from 75 ° C to 95 ° C. The temperature of the residue in line 133 is preferably from 70 ° C to 115 ° C, such as from 80 ° C to 110 ° C or from 85 ° C to 110 ° C.

In one embodiment, a portion of the third residue in line 124 is recycled to second column 123. In one embodiment, recycling the third residue further reduces the aldehyde component in the second residue and concentrating the aldehyde component in the second distillate in line 127 and thus to the first Four columns 131, wherein the aldehyde may be easier to separate. The third distillate in line 129, such as the intermediate stream, may have lower concentrations of aldehydes and esters because of the third residue in line 124 being recycled.

Figure 2 illustrates another exemplary separation system having a reaction zone 101 similar to that of Figure 1 and produces a liquid stream 112 such as a crude mixture of ethanol for further separation. In one embodiment, the reaction zone 101 of Figure 2 operates at greater than 70% acetic acid conversion, such as greater than 85% conversion or greater than 90% conversion. Thus, the concentration of acetic acid in liquid stream 112 can be lower.

Liquid stream 112 is fed into first column 134 to produce first distillate 135 and first residue 136. The liquid stream 112 can be directed to the middle or lower portion of the first column 134, which is also referred to as an acid-water column. In a specific example, no entrainers are added to the first column 134. Water and acetic acid are removed from liquid stream 112 along with any other heavy components present and are withdrawn as a residue in line 136 (preferably continuously withdrawn). Preferably, a substantial portion of the water fed to the crude ethanol mixture of first column 134 can be removed from the first residue, for example up to about 70% or up to about 90% from the crude ethanol mixture. In one embodiment, 30 to 90% of the water in the crude ethanol mixture is removed from the residue, for example from 40 to 88% water or from 50 to 84% water.

The first column 134 can be operated under boost to promote separation of the diethyl acetal. When tower 134 is in When operating at 170 kPa, the temperature of the residue flowing out of line 136 is preferably from 90 ° C to 130 ° C, such as from 95 ° C to 120 ° C or from 100 ° C to 115 ° C. The temperature of the distillate flowing out of line 135 is preferably from 60 ° C to 90 ° C, such as from 65 ° C to 85 ° C or from 70 ° C to 80 ° C. In some embodiments, the pressure of the first column 134 may also range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa.

The first distillate in line 135 also includes water in addition to ethanol and other organics. When expressed in terms of range, the water concentration in the first distillate in line 135 is preferably from 4% to 38% by weight, such as from 7% to 32% by weight or from 7% to 25% by weight. A portion of the first distillate in line 137 can be refluxed and refluxed, for example, from 10:1 to 1:10, such as from 3:1 to 1:3 or from 1:2 to 2:1. It will be appreciated that the reflux ratio can vary with order, feed location, column efficiency, and/or feed composition. Operating at a reflux ratio greater than 3:1 may be less desirable as more energy may be required to operate the first column 134. The condensed portion of the first distillate may also be fed to the second column 138.

The first distillate of the remainder of line 139 is fed to water separation unit 140. The water separation unit 140 can be an adsorption unit, a membrane, a molecular sieve, an extraction column distillation, or a combination thereof. A membrane or membrane array can also be utilized to separate water from the distillate. The membrane or membrane array can be selected from any suitable membrane that can remove the permeate stream from a stream that also includes ethanol and ethyl acetate.

In a preferred embodiment, the water separator 140 is a pressure swing adsorption (PSA) unit. The PSA unit is operated at a pressure from 30 ° C to 160 ° C, such as from 80 ° C to 140 ° C, and from 0.01 kPa to 550 kPa, such as from 1 kPa to 150 kPa. The PSA unit can include two to five beds. The water separator 140 can remove at least 95% of the water from a portion of the first distillate of line 139, and more preferably from 99% to 99.99% of the water in the aqueous stream 141 from the first distillate. All or a portion of the aqueous stream 141 can be returned to the first column 134 in line 142 where the final water is preferably recovered from column 134 to the first residue in line 136. Additionally or optionally, all or a portion of the aqueous stream 141 can be purged by line 143. The remaining portion of the first distillate exits the water separator 140 as an ethanol mixture stream 144. The ethanol mixture stream 144 can have a lower water concentration of less than 10% by weight, such as less than 6% by weight or less than 2% by weight.

Preferably, the ethanol mixture stream 144 is not returned or refluxed to the first column 135. The first distillate in the condensed portion of line 137 can be combined with the ethanol mixture stream 144 to control the feed. The concentration of water in the second column 138. For example, in some embodiments, the first distillate is split into equal portions, while in another embodiment, all of the first distillate may be condensed or all of the first distillate may be treated in a water separation unit. . In FIG. 2, the condensed portion of line 137 and the ethanol mixture stream 144 are fed together into second column 138. In other embodiments, the condensed portion of the line 137 and the ethanol mixture stream 144 can be fed to the second column 138, respectively. The combined distillate and ethanol mixture has a total water concentration of greater than 0.5% by weight, such as greater than 2% by weight or greater than 5% by weight. The total water concentration of the combined distillate and ethanol mixture, as indicated by the range, may range from 0.5 to 15% by weight, such as from 2 to 12% by weight or from 5 to 10% by weight.

The second column 138 in Figure 2, also referred to as a "light hydrocarbon column", can be removed from the first distillate and/or ethanol mixture stream 144 in line 137 to remove ethyl acetate and acetaldehyde. Ethyl acetate and acetaldehyde were removed as the second distillate in line 145 and the ethanol was removed as the second residue in line 146. Preferably, the ethanol is recovered as containing a small amount of ethyl acetate, acetaldehyde and/or acetal, such as less than 1% by weight or more preferably less than 0.5% by weight. The ethanol product obtained from the second residue of Figure 2 is also shown in Table 3 below. Preferably, the ethanol product comprises less than 1% by weight of diethyl acetal, such as less than 0.5% by weight or less (0.01% by weight.

The second column 138 can be a plate column or a packed column. In one embodiment, the second column 138 is a plate column having a theoretical plate number of 5 to 120, such as from 15 to 100 theoretical plates or from 20 to 90 theoretical plates. In one embodiment, the stripping section of the second column 138 has at least 40 steps, such as at least 50 steps or at least 60 steps. Additional steps in the stripping section promote acetal hydrolysis.

In one embodiment, the second column 138 is operated at a pressurization from 101 kPa to 5,000 kPa, such as from 120 kPa to 4,000 kPa, from 150 kPa to 3,000 kPa. The pressurization of the second column 138 can in turn promote hydrolysis of the acetal, particularly diethyl acetal, in the second column 138. When the first column 134 is operated under boost, the second column 138 can be operated at a pressure from 0.1 kPa to 510 kPa, such as from 10 kPa to 450 kPa or from 50 kPa to 350 kPa. Although the temperature of the second column 138 is variable, when at about 20 kPa to 70 kPa, the temperature of the second residue flowing out of the line 146 is preferably from 30 ° C to 75 ° C, such as from 35 ° C to 70 ° C or from 40 ° C to 65 ° C. The temperature of the second distillate flowing out of line 145 is preferably from 20 ° C to 55 ° C, such as from 25 ° C to 50 ° C or from 30 ° C to 45 ° C.

The total water concentration fed into the second column 138 is preferably less than 10% by weight as described above. When the first distillate and/or ethanol mixture stream 144 in line 137 includes a small amount of water, such as less than one weight If the amount is % or less than 0.5% by weight, additional water may be fed to the upper portion of the second column 138 as an extractant. Preferably, sufficient water is added via the extractant such that the total water concentration fed to the second column 138 is from 1 to 10% by weight, such as from 2 to 6 weight, based on the total of all components fed to the second column 138. Recalculation. If the extractant comprises water, the water can be obtained from an external source or from an internal return/recycle line of one or more other columns or water separators.

Suitable extractants may also include, for example, dimethyl hydrazine, glycerin, diethylene glycol, 1-naphthol, hydroquinone, N, N'-dimethylformamide, 1,4-butanediol; Alcohol-1,5-pentanediol; propylene glycol-tetraethylene glycol-polyethylene glycol; glycerol-propylene glycol-tetraethylene glycol-1,4-butanediol, diethyl ether, methyl formate, cyclohexane, N , N'-dimethyl-1,3-propanediamine, N,N'-dimethylethylenediamine, diethylenetriamine, hexamethylenediamine and 1,3-diaminopentane Alkane, alkylated thiophene, dodecane, tridecane, tetradecane, chlorinated paraffin or combinations thereof. When an extractant is used, a suitable recovery system such as an additional distillation column can be used to recycle the extractant.

The second distillate comprising ethyl acetate and/or acetaldehyde in line 145 is preferably refluxed as shown in Figure 2, for example from 1:30 to 30:1, such as from 1:10 to 10:1 or from 1:3 to 3:1 reflux ratio reflux. In one aspect, not shown, the second distillate 145 or a portion thereof can be returned to the reactor 103.

In one embodiment, the second distillate in line 145 and/or one or both of the purified second distillate or fraction may be separated to produce an acetaldehyde-containing stream and ethyl acetate. The flow of liquid. For example, the fourth column 131 can be used to separate the second distillate in line 145 as shown in FIG. This allows a portion of the resulting acetaldehyde-containing or ethyl-containing stream to be recycled to reactor 103 while blowing to purge other streams. The purge liquid stream may be of value as a source of ethyl acetate and/or acetaldehyde.

In one embodiment, the second column 138 in Figure 2 is preferably operated at subatmospheric pressure to reduce the energy required to separate the ethyl acetate and ethanol. However, reduced pressure may be disadvantageous for promoting hydrolysis of diethyl acetal. Figure 3 shows a process similar to that of Figure 2, but the first distillate and/or ethanol mixture stream 144 in line 137 is split and the first portion is fed via line 147 to the high pressure second column 148, and the second A portion of the low pressure second column 150 is fed via line 149. The relative amount of feed to the higher pressure second column 148 and to the lower pressure second column 150 can be controlled based on the concentration of diethyl ester and/or ethyl acetate in the ethanol-containing residue. When the concentration of diethyl acetal in the ethanol-containing residue is increased Additionally, a larger portion of the first distillate and/or ethanol mixture stream 144 in line 137 can be fed to line 147. Likewise, as the ethyl acetate concentration increases, a larger portion can be fed into the lower pressure second column 150 via line 149. A control valve can be used to regulate the flow between the first and second portions.

In Fig. 3, the high pressure second column 148 is operated at a supercharge above atmospheric pressure to produce a distillate comprising ethyl acetate, acetaldehyde and diethyl acetal in line 151 and included in line 152. Residue of ethanol. In one embodiment, the residue in line 152 contains a low concentration of diethyl acetal, such as less than 1% by weight or less than 0.5% by weight. The high pressure second column 148 also has at least 40 stages, such as at least 50 steps or at least 60 steps of the increased stripping section.

The low pressure second column 150 is operated in a vacuum or below atmospheric pressure, such as below 70 kPa or below 50 kPa. The low pressure second column 150 can be operated from 0.1 to 100 kPa, such as from 0.1 to 70 kPa or from 0.1 to 35 kPa, as indicated by the second column. This reduced pressure further enhances the separation of ethyl acetate from ethanol. The low pressure second column 150 also produces a distillate comprising ethyl acetate, acetaldehyde and diethyl acetal in line 135 and a residue comprising ethanol in line 154. In one embodiment, the residue in line 154 contains a low concentration of ethyl acetate, such as less than 1% by weight or less than 0.5% by weight.

The distillate of the columns can be combined and returned to the reactor 103 in a manner similar to that shown in Figure 2 above. In addition, the residues of the columns in Figure 3 can be combined to produce an ethanol product. In some embodiments, it may be preferred to produce separated ethanol from each of the second columns 148 and 150 of Figure 3.

Figure 3 illustrates the parallel high voltage and low pressure towers. In some specific cases, it may be necessary to operate the high pressure and low pressure columns in series. Figure 4 illustrates a process in which the first distillate and/or ethanol mixture stream 144 in line 137 is fed first to the low pressure second column 150. As noted above, the residue in line 154 may have a low concentration of ethyl acetate, but may also have a higher concentration of ethyl acetate. The residue in line 154 is fed to a higher pressure second column 148 to promote hydrolysis of the diethyl acetal. In the high pressure second column 148, the diethyl acetal is hydrolyzed to produce a distillate comprising acetaldehyde in line 151 and a residue comprising ethanol in line 152. Using the high pressure second column 148, at least 20% diethyl acetal in the residue of line 154 can be hydrolyzed, such as at least 30% or at least 50%. Thus, the diethyl acetal concentration in the residue of line 152 can be less than 1% by weight, such as less than 0.5% by weight.

Figure 5 reverses the low pressure second column 150 and the high pressure second column 148 in Figure 4. Figure 5 illustrates the process in which the first distillate and/or ethanol mixture stream 144 in line 137 is fed first to the high pressure second column 148. As noted above, the residue in line 152 can have a low concentration of diethyl acetal, but can also have a higher concentration of ethyl acetate. In the second column 148 of high pressure, the diethyl acetal is hydrolyzed to produce a distillate in line 151 and a residue comprising ethanol in line 152. The distillate in line 151 is fed to a low pressure second column 150. The distillate in line 151 can include ethyl acetate and ethanol and it is preferred to recover the ethanol instead of recycling the ethanol to reactor 103. Using low pressure second column 150, any ethanol in the distillate of line 151 is separated as a residue in line 154 and ethyl acetate is removed as a distillate in line 153. The distillate in line 153 is recycled to reactor 103. The residue in line 154 can be combined with the residue in line 152 to form an ethanol product. In some embodiments, each residue stream can be used as a separate ethanol product.

Returning to Figure 2, the pressure of the second column can vary depending on the concentration of diethyl acetal in the second residue of line 146. When the diethyl acetal concentration is increased above the second residue of line 146 by more than, for example, 1% by weight, the pressure of second column 138 also increases. Further, when the ethyl acetate concentration in the second residue of line 146 is higher than, for example, 1% by weight, the pressure of second column 138 can be lowered. This allows the second column 138 to be adjusted as needed without the need for additional capital from other distillation columns.

In other embodiments, the liquid stream 112 from the reaction zone 101 can be separated using the process illustrated in FIG. In a preferred embodiment, reaction zone 101 of Figure 6 operates at a conversion of greater than 80% acetic acid, such as greater than 90% or greater than 99% acetic acid conversion. Therefore, the concentration of acetic acid in liquid stream 112 may be lower.

In the specific example shown in Fig. 6, the liquid stream 112 is introduced into the upper portion of the first column 160, such as the upper half or the upper third. In one embodiment, no entrainer is added to the first column 160. In the first column 160, the major weight portion of ethanol, water, acetic acid, and other heavy components present, if removed from the liquid stream 112, is withdrawn as a residue of line 162, preferably continuously withdrawn. The first column 160 also forms an overhead which is withdrawn from line 161 and which may be condensed and, for example, from 30:1 to 1:30, such as from 10:1 to 1:10 or from 1:5 The reflux ratio of 5:1 is reflux. The first distillate in line 161 preferably includes the major weight from liquid line 112. A portion of the ethyl acetate. In addition, the distillate in line 161 also includes acetaldehyde.

In one embodiment, the first column 160 can be operated under boost to promote hydrolysis of the diethyl acetal. In addition, the first column 160 can also have a stripping section that includes at least 40 steps, such as at least 50 steps or at least 60 steps.

When column 160 is operated at about 170 kPa, the temperature of the residue flowing out of line 162 is preferably from 70 ° C to 155 ° C, such as from 90 ° C to 130 ° C or from 100 ° C to 110 ° C. The column 160 substrate can be held at a relatively low temperature by extracting a stream of residues including ethanol, water, and acetic acid, thereby providing an energy efficiency advantage. The temperature of the distillate flowing out of line 161 at 170 kPa is preferably from 75 ° C to 100 ° C, such as from 75 ° C to 83 ° C or from 81 ° C to 84 ° C.

In some embodiments, when the second column 163 of Figure 6 is operated under boost, the pressure of the first column 170 can range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa.

In a specific embodiment of the invention, the column 160 of Figure 6 can be operated at a temperature at which most of the water, ethanol and acetic acid are removed from the residue stream and is only small due to the formation of a binary azeotrope and a ternary azeotrope. Part of the ethanol water collection is taken up in the distillate stream. The weight ratio of water in the residue of line 162 to water in the distillate of line 161 can be greater than 1:1, such as greater than 2:1. The weight ratio of the ethanol of the residue to the ethanol in the distillate may be greater than 1:1, such as greater than 2:1.

The amount of acetic acid in the first residue can vary primarily depending on the conversion of the reactor 103. In one embodiment, when the conversion is high, for example, greater than 90%, the amount of acetic acid in the first residue may be less than 10% by weight, such as less than 5% by weight or less than 2% by weight. In other specific examples, when the conversion rate is as low as 90%, the amount of acetic acid in the first residue may be more than 10% by weight.

The distillate is preferably substantially free of acetic acid, such as comprising less than 1000 wppm, less than 500 wppm or less than 100 wppm acetic acid. The distillate may be purged from the system or completely or partially recycled to the reactor 103. In some embodiments, the distillate may be further separated into an acetaldehyde stream and an ethyl acetate stream in a fourth column as selected in Figure 1. One of the streams can be returned to reactor 103 or separated from system 100 to separate the product.

To recover the ethanol, the residue in line 162 can be further separated in a second column 163, also referred to as an "acid separation column." An acid separation column can be used when the concentration of acetic acid in the first residue is greater than 1% by weight, such as greater than 5% by weight. Introducing the first residue in line 162 In the second column 163, it is preferably the upper end portion of the introduction column 163, the upper half or the upper third. Second column 163 is produced in line 165 comprising a second residue of acetic acid and water and a second distillate comprising ethanol in line 164.

The second column 163 can be a plate column or a packed column. In one embodiment, the second column 163 is a plate column having a theoretical plate number of 5 to 150, such as from 15 to 50 theoretical plates or from 20 to 45 theoretical plates. Similar to the first column 160, the second column can have a stripping section of at least 40 steps, such as at least 50 steps or at least 60 steps.

In one embodiment, the second column 163 can be operated under boost to promote hydrolysis of the diethyl acetal. In Fig. 6, it is better that the first column 160 is operated under a pressurization because the second column 163 includes a very small amount of acetaldehyde and/or acetal. Generally, the pressure of the second column 163 can range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa. The temperature of the second residue flowing out of line 165 at atmospheric pressure is preferably from 95 ° C to 130 ° C, such as from 100 ° C to 125 ° C or from 110 ° C to 120 ° C. The temperature of the second distillate flowing out of line 164 is preferably from 60 ° C to 105 ° C, such as from 75 ° C to 100 ° C or from 80 ° C to 100 ° C.

Preferably, the second distillate of line 164 has a weight of ethanol of at least 35:1 for the second residue of line 165. In one embodiment, the weight ratio of water in the second residue 165 to water in the second distillate 164 is greater than 2:1, such as greater than 4:1 or greater than 6:1. Further, the weight ratio of acetic acid in the second residue 165 to acetic acid in the second distillate 164 is greater than 10:1, such as greater than 15:1 or greater than 20:1. Preferably, the second distillate in line 164 is substantially free of acetic acid and may contain only traces, if any, of acetic acid. Preferably, the second distillate in line 164 is substantially free of ethyl acetate.

The remaining water from the second distillate in line 164 can be removed in other embodiments of the invention. The ethanol product may be derived from the second distillate in line 164 depending on the water concentration. Some applications, such as industrial ethanol, can tolerate water in ethanol products, while other applications, such as fuel applications, may require anhydrous ethanol. The amount of water in the distillate of line 164 may be closer to the azeotrope of water, such as at least 4% by weight, preferably less than 20% by weight, such as less than 12% by weight or less than 7.5% by weight. Water can be removed from the second distillate in line 164 using several different separation techniques described herein. A particularly preferred technique involves the use of a distillation column, membrane, adsorption unit, or a combination thereof.

Some of the residue extracted from the separation zone 102 includes acetic acid and water. Depending on the residue of the first column, such as the amount of water and acetic acid contained in the first residue 120 in Figure 1, the residue may be treated in one or more of the following processes. The following is a list of processes for further processing of residues and it should be understood that any of the following processes can be used regardless of the concentration of acetic acid. When the residue comprises a majority of acetic acid, such as greater than 70% by weight, the residue can be recycled to the reactor without separating any water. In one embodiment, when the residue comprises a major amount of acetic acid, such as greater than 50% by weight, the residue can be separated into an acetic acid stream and a water stream. In some embodiments, acetic acid can also be recovered from residues having a lower acetic acid concentration. The residue can be separated into acetic acid and water by a distillation column or one or more membranes. If a membrane or array of membrane arrays is used to separate acetic acid from water, the membrane or array of membrane arrays can be selected from any suitable acid resistant membrane that can be removed from the permeate stream. The resulting acetic acid liquid stream is returned to the reactor 103 as the case may be. The resulting aqueous stream can be used as an extractant or to hydrolyze an ester-containing stream in a hydrolysis unit.

In other specific examples, such as when the residue comprises less than 50% by weight acetic acid, possible options include one or more of the following: (i) returning a portion of the residue to reactor 103, (ii) neutralizing the acetic acid (iii) reacting acetic acid with an alcohol or (iv) discarding the residue in a wastewater treatment plant. It is also possible to separate the residue comprising less than 50% by weight of acetic acid using a weak acid recovery distillation column in which a solvent may be added, optionally acting as an entrainer. Examples of solvents suitable for this purpose comprises ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, vinyl acetate, diisopropyl ether, carbon disulfide, tetrahydrofuran, isopropanol, ethanol and C ₃ -C ₁₂ alkanes class. When neutralizing acetic acid, it is preferred that the residue comprises less than 10% by weight acetic acid. The acetic acid can be neutralized with any suitable alkali or alkaline earth metal base such as sodium hydroxide or potassium hydroxide. When acetic acid is reacted with an alcohol, it is preferred that the residue comprises less than 50% by weight of acetic acid. The alcohol can be any suitable alcohol such as methanol, ethanol, propanol, butanol or mixtures thereof. The reaction forms an ester which can be integrated with other systems, such as a carbonylation or ester manufacturing process. Preferred alcohols include ethanol and the resulting esters include ethyl acetate. The resulting ester can be fed to the hydrogenation reactor, as appropriate.

In some embodiments, when the residue comprises a trace amount of acetic acid, such as less than 5% by weight, the residue can be disposed of in a wastewater treatment plant without further processing. The organic content of the residue, such as the acetic acid content, may be advantageously suitable for cultivating microorganisms in a wastewater treatment plant.

The column shown in the drawings can include any distillation column that can perform the desired separation and/or alcoholation. For example, an acid tower other than the above, which is preferably a plate column having a theoretical plate number of 1 to 150, such as from 10 to 100 theoretical plates, from 20 to 95 theoretical plates, or from 30 to 75 theoretical plates. . The tower can be a screen deck, a fixed valve plate, a movable valve plate, or any suitable design known in the art. In other specific examples, a packed column can be used. In the case of packed columns, structured packed columns or randomly packed columns can be utilized. The plates or fills may be arranged in a continuous column or may be arranged in two or more columns such that steam from the first stage enters the second stage while allowing liquid from the second stage to enter the first stage and many more.

The associated condenser and liquid separation vessel that can be used with each distillation column can be of any conventional design and simplified in the drawings. Heat can be applied to each column substrate or to a circulating bottom stream via a heat exchanger or reboiler. Other types of reboilers such as internal reboilers can also be used. The heat provided to the reboiler can be derived from any heat generated during the process of integration with the reboiler or from external sources such as other chemical processes or boilers. Although a reactor and a flasher are shown in the drawings, additional reactors, flashers, condensers, heating elements, and other components can be used in various embodiments of the invention. As is well understood in the art, various condensers, pumps, compressors, reboilers, drums, valves, connectors, separation vessels, and the like, which are generally used for chemical processes, can also be combined and used in the process of the present invention.

The temperature and pressure used in the tower can be varied. The temperature in the various zones is generally in the range between the composition removed by the distillate and the boiling point of the composition removed as a residue. As is well understood by those skilled in the art, the temperature at which the distillation column is operated is determined by the material composition at that location and the pressure within the column. In addition, the feed rate can vary with the size of the manufacturing process and is generally referred to as the feed weight ratio if described.

The final ethanol product produced by the process of the present invention can be taken from a stream comprising primarily ethanol from the enumerated systems shown in the scheme. The ethanol product can be an industrial grade ethanol comprising from 75 to 96 weight percent ethanol, such as from 80 to 96 weight percent or from 85 to 96 weight percent ethanol, based on the total weight of the ethanol product. The range of completed ethanol compositions listed is shown in Table 3 below.

The finished ethanol composition of the present invention preferably comprises a minor amount, such as less than 0.5% by weight, of other alcohols such as methanol, butanol, isobutanol, isoamyl alcohol and other C ₄ -C ₂₀ alcohols. In one embodiment, the amount of isopropanol in the finished ethanol composition is from 80 to 1,000 wppm (ppm by weight), such as from 95 to 1,000 wppm, from 100 to 700 wppm, or from 150 to 500 wppm. In one embodiment, the finished ethanol composition is substantially free of acetaldehyde, optionally including less than 8 wppm acetaldehyde, such as less than 5 wppm or less than 1 wppm.

In some specific examples, when water separation is further used, the ethanol product can be withdrawn as a liquid stream from the water separation unit as described above. In this particular example, the ethanol product may have an ethanol concentration greater than that described in Table 3, and more preferably greater than 97% by weight ethanol, such as greater than 98% by weight or greater than 99.5% by weight. Preferably, the ethanol product comprises less than 3% by weight water, such as less than 2% by weight or less than 0.5% by weight water, in this regard.

The finished ethanol composition prepared by the specific examples of the present invention can be used for various purposes, including as a fuel, a solvent, a chemical raw material, a pharmaceutical product, a detergent, a disinfectant, a hydrogenation transfer, or a hydrogen consumption. In fuel applications, the finished ethanol composition can be blended with gasoline for vehicles such as automobiles, boats, and small piston engine aircraft. For non-fuel applications, the finished ethanol composition can be used as a solvent for hygiene and cosmetic preparations, detergents, disinfectants, coatings, inks, and pharmaceuticals. The finished ethanol composition can also be used as a processing solvent in the manufacturing process of pharmaceutical products, food preparations, dyes, photochemicals, and latex processing.

The completed ethanol composition can also be used as a chemical raw material to produce other chemicals such as vinegar, ethyl acrylate, ethyl acetate, ethylene, glycol ethers, ethylamines, aldehydes, and higher alcohols, especially butanol. In the manufacture of ethyl acetate, the finished ethanol composition can be esterified with acetic acid. In other applications, the finished ethanol composition can be dehydrated to produce ethylene. Any of the known dehydration catalysts can be used to dehydrate the ethanol, as described in the unexamined U.S. Patent Publication Nos. 2010/0030002 and 2010/003, the entire disclosures of which are incorporated herein by reference. For example, a zeolite catalyst can be used as the dehydration catalyst. Preferably, the zeolite has a pore diameter of at least about 0.6 nm, and preferably the zeolite comprises a dehydration catalyst selected from the group consisting of mordenite, ZSM-5, zeolite X and zeolite Y. Zeolite X is described in, for example, U.S. Patent No. 2,882,244, the disclosure of which is incorporated herein by reference.

Although the invention has been described in detail, it will be apparent to those skilled in the art In view of the above discussion, the related art in the above-described technical background and embodiments, and the related knowledge in the references, are incorporated herein by reference. In addition, it should be understood that the objects of the invention and the various specific embodiments and various features of the invention described in the following and/or the appended claims may be combined or interchanged in whole or in part. In the foregoing description of the specific examples, the specific examples of the other specific examples may be appropriately combined with one or more other specific examples, which are known to those skilled in the art. In addition, those skilled in the art will understand that the foregoing description is by way of example only and is not intended to limit the invention.

100‧‧‧Hydrogenation systems/systems/processes

101‧‧‧Reaction zone

102‧‧‧Separation zone

104‧‧‧Line/hydrogen feed

105‧‧‧ pipeline

106‧‧‧Vaporizer

107‧‧‧ pipeline

109‧‧‧ pipeline

110‧‧‧Separator

111‧‧‧Steam flow

112‧‧‧Liquid flow

120‧‧‧First Tower/Acid Separation Tower

121‧‧‧ pipeline

122‧‧‧ pipeline

123‧‧‧Second Tower/Light Hydrocarbon Tower

124‧‧‧ pipeline

125‧‧‧ pipeline

126‧‧‧ pipeline

127‧‧‧ pipeline

128‧‧‧ Third Tower/Product Tower

129‧‧‧ pipeline

131‧‧‧Fourth Tower/Acetaldehyde Removal Tower

132‧‧‧ pipeline

133‧‧‧ pipeline

134‧‧‧First Tower/Acid-Water Tower/Tower

135‧‧‧Line/first distillate

136‧‧‧First residue

137‧‧‧ pipeline

138‧‧‧Second Tower/Light Hydrocarbon Tower

139‧‧‧ pipeline

140‧‧‧Water separation unit

141‧‧‧Water flow

142‧‧‧ pipeline

144‧‧‧Ethanol mixture flow

145‧‧‧ pipeline

146‧‧‧ pipeline

147‧‧‧ pipeline

148‧‧‧High Pressure Second Tower

149‧‧‧ pipeline

150‧‧‧Low pressure second tower

151‧‧‧ pipeline

152‧‧‧ pipeline

153‧‧‧ pipeline

154‧‧‧ pipeline

160‧‧‧First Tower/Tower

161‧‧‧ pipeline

162‧‧‧ pipeline

163‧‧‧Second Tower/Acid Separation Tower

164‧‧‧Line/second distillate

165‧‧‧Line/Second residue

The present invention will be described in more detail with reference to the accompanying drawings, in which,

Fig. 1 is a schematic view showing a hydrogenation process having four columns in accordance with an embodiment of the present invention.

Fig. 2 is a schematic view showing another hydrogenation process having two columns and having water separation according to an embodiment of the present invention.

Fig. 3 is a schematic view showing the separation of the partitioning water having the second embodiment of the high pressure and low pressure columns in parallel according to an embodiment of the present invention.

4 and 5 are schematic views of the separation of the partitioning water having the second embodiment of the high pressure and low pressure column in series according to an embodiment of the present invention.

Figure 6 is a schematic illustration of another hydrogenation process with two columns in accordance with one embodiment of the present invention.

100‧‧‧Hydrogenation systems/systems/processes

101‧‧‧Reaction zone

102‧‧‧Separation zone

104‧‧‧Line/hydrogen feed

105‧‧‧ pipeline

106‧‧‧Vaporizer

107‧‧‧ pipeline

109‧‧‧ pipeline

110‧‧‧Separator

111‧‧‧Steam flow

112‧‧‧Liquid flow

120‧‧‧First Tower/Acid Separation Tower

121‧‧‧ pipeline

122‧‧‧ pipeline

123‧‧‧Second Tower/Light Hydrocarbon Tower

124‧‧‧ pipeline

125‧‧‧ pipeline

126‧‧‧ pipeline

127‧‧‧ pipeline

128‧‧‧ Third Tower/Product Tower

129‧‧‧ pipeline

131‧‧‧fourth tower

132‧‧‧ pipeline

133‧‧‧ pipeline

Claims (15)

A method for producing ethanol, comprising: hydrogenating an alkanoic acid and/or its ester in the presence of a catalyst in a reactor to form acetaldehyde, ethanol, water, diethyl acetal and, if appropriate, ethyl acetate And a crude mixture of alkanoic acid in ethanol; and separating the crude ethanol mixture in one or more columns to recover an ethanol product comprising less than 1% by weight of diethyl acetal, wherein at least one of the columns is operated above atmospheric pressure. The method of claim 1, wherein the separating step comprises: separating a portion of the crude ethanol mixture in the first distillation column to produce a first residue comprising an alkanoic acid, and comprising ethanol, acetaldehyde, and optionally a first distillate of water and ethyl acetate; separating a portion of the first distillate in a second distillation column to produce a second residue comprising ethanol and optionally water, and including acetaldehyde and optionally a second distillate of ethyl acetate; optionally separating a portion of the second residue in a third distillation column operated to produce a third residue comprising water, and a third distillate comprising ethanol; At least a portion of the first residue and/or second distillate is returned to the reactor as appropriate; and at least a portion of the third residue is returned to the second distillation column as appropriate. The method of claim 1, wherein the separating step comprises: separating a portion of the crude ethanol mixture in the first distillation column to produce a first residue comprising a majority of water fed to the distillation column, and a first distillate comprising ethanol, acetaldehyde, water and, optionally, ethyl acetate; water is removed from the first distillate to produce an ethanol mixture stream; and the portion of the ethanol is separated in a second distillation column The mixture is flowed to produce a second residue comprising ethanol and less than 1% by weight of diethyl acetal, and a second distillate comprising acetaldehyde and, optionally, ethyl acetate; optionally from 0.1 to 100 kPa Separating a second portion of the ethanol mixture stream in a third distillation column operated under pressure to produce a third residue comprising ethanol, and a third distillate comprising acetaldehyde and, optionally, ethyl acetate; Three residues including less than one weight Amount of ethyl acetate; optionally separating a portion of the second distillate in a fourth distillation column operated at a pressure of 0.1 to 100 kPa to produce a fourth residue comprising ethanol, and including acetaldehyde and optionally a fourth distillate of ethyl acetate; wherein the fourth residue comprises less than 1% by weight ethyl acetate; and optionally at least a portion of the second distillate is returned to the reactor. The method of claim 1, wherein the separating step comprises: separating a portion of the crude ethanol mixture in the first distillation column operated at above atmospheric pressure to produce a first alcohol comprising ethanol, water, and optionally acetic acid. a residue, and a first distillate comprising ethyl acetate and acetaldehyde; separating a portion of the first residue in a second distillation column to produce a second residue comprising water and optionally acetic acid, And a second distillate comprising ethanol; and optionally at least a portion of the first distillate and/or second residue is returned to the reactor. The method of any one of claims 2 to 4, wherein the second distillation column is operated at a pressure higher than the first column. The method of any one of claims 2 to 4, wherein the first distillation column is operated at a pressure higher than the second column. The method of any one of claims 1 to 4, wherein at least one of the columns operating at above atmospheric pressure is operated at a pressure of from 100 kPa to 5,000 kPa. The method of any one of claims 1 to 7, wherein the ethanol product comprises from 0.0001 to 0.01% by weight of diethyl acetal. The method of any one of claims 1 to 8 further comprising decomposing at least 10 to 75% diethyl acetal in at least one column operating at atmospheric pressure. The method of any one of claims 1 to 9, wherein at least one of the columns has a stripping section comprising at least 40 stages, preferably at least 60 steps. The method of any one of claims 1 to 10, wherein the alkanoic acid is formed from methanol and carbon monoxide, wherein the methanol, the carbon monoxide, and the hydrogen used in the hydrogenating step are derived from syngas, and Wherein the syngas is derived from a carbon source selected from the group consisting of natural A group of gas, crude oil, petroleum, coal, biomass materials, and combinations thereof. The method of any one of claims 3, 5 to 11, wherein the first residue comprises from 30 to 90% of the water in the crude ethanol mixture. The method of any one of claims 3 to 5, wherein the ethanol mixture stream comprises less than 10% by weight water. The method of any one of claims 3, 5 to 13, wherein the water is removed from the distillate using an adsorption unit or membrane. The method of any one of claims 4 to 14, wherein a majority of the weight of the ethanol in the crude ethanol mixture is separated in the first residue.