HK1164271A - Processes for producing denatured ethanol - Google Patents

Description

Method for producing denatured ethanol

Priority requirement

This application claims priority from: U.S. provisional application No.61/300,815 filed on 2/2010, U.S. provisional application No.61/332,727 filed on 5/7/2010, and U.S. provisional application No.61/332,696 filed on 5/7/2010; and U.S. application No.12/889,260 filed on 23/9/2010, which are incorporated herein by reference in their entirety.

Technical Field

The present invention relates generally to processes for producing denatured ethanol compositions, and in particular, to processes for producing denatured ethanol compositions by the hydrogenation of acetic acid to form a crude ethanol product and a denaturant.

Background

Produced ethanol is commonly used as a component in a variety of consumer products such as beer (beer), wine (wine) and spirit (spirit). Typically, ethanol intended for such use is produced by fermentation. Many government agencies impose taxes on consumable ethanol, thereby increasing consumer costs.

However, there are many other uses for ethanol that do not involve consumption, such as fuels, chemical solvents, or pharmaceuticals. As such, in an effort to provide inexpensive ethanol for non-consumer use, the tax imposed on consumer ethanol is typically not required for ethanol that is not intended to be consumed. To ensure that such ethanol compositions are used in non-consumer applications, most countries have laws and regulations requiring that these ethanol compositions contain denaturants that are added to an otherwise substantially pure ethanol composition to render the ethanol unfit for drinking. Thus, ethanol compositions that contain denaturants and are not intended for consumption are often referred to as "denatured ethanol" or "denatured alcohol (alcohol)". Conventional denaturants include methanol, isopropanol, acetone, methyl ethyl ketone, ethyl acetate, methyl isobutyl ketone, and acetaldehyde.

The processing step of adding denaturants to an otherwise potable ethanol composition adds complexity and cost to the conventional denatured ethanol formation process. Thus, there is a need for new and improved methods of denatured ethanol formation.

Summary of The Invention

In a first embodiment, the present invention relates to a process for producing a denatured ethanol composition, the process comprising: hydrogenating acetic acid in the presence of a catalyst to form a caide ethanol product comprising ethanol and at least one denaturant; separating the caide ethanol product in one or more separation units into a denatured ethanol composition and one or more derivative streams, wherein the denatured ethanol composition, as formed, comprises from 0.01 wt.% to 40 wt.% of a denaturant, based on the total weight of the denatured ethanol composition.

In a second embodiment, the present invention relates to a process for producing a denatured ethanol composition, the process comprising: hydrogenating acetic acid in the presence of a catalyst to form a crude ethanol product comprising ethanol and a denaturant; separating the caide ethanol product into an ethanol stream and at least one derivative stream comprising the separated denaturant; further purifying the ethanol stream to form a purified ethanol stream; and combining at least a portion of the separated denaturant with the purified ethanol stream to produce a denatured ethanol composition.

Drawings

The present invention is described in detail below with reference to the attached drawing figures, wherein like numerals indicate like parts.

FIG. 1A is a schematic diagram of a hydrogenation system according to one embodiment of the invention.

FIG. 1B is a schematic of the system shown in FIG. 1A in which the distillate of the second column is returned to the reactor zone.

FIG. 1C is a schematic diagram of a hydrogenation system according to one embodiment of the invention.

Fig. 2 is a graph showing the composition of an exemplary second residue stream at various tray locations within the third column.

Detailed Description

Conventional denatured ethanol production processes begin with the production of purified ethanol. In these processes, ethanol may be formed and subsequently purified by conventional methods. The denaturant is then added to the purified ethanol to form denatured ethanol.

The present invention relates to a process for producing denatured ethanol compositions. In one embodiment, the present invention relates to a process comprising the steps of: for example, acetic acid is hydrogenated in the presence of a catalyst to form a crude ethanol product. The crude ethanol product comprises at least one, such as at least two or at least three, denaturants. In one embodiment, the denaturant may be co-produced with the ethanol. In another embodiment, the denaturant is formed as a byproduct of the hydrogenation reaction. In other words, the denaturant is formed in situ with the ethanol. In one embodiment, the process of the present invention further comprises separating the caide ethanol product into a denatured ethanol composition and one or more derivative streams. The separation may be carried out in one or more, e.g. two or more, or three or more separation units (e.g. distillation columns). The resulting denatured ethanol composition, as formed, is derived from acetic acid and comprises 0.01 wt.% to 40 wt.%, e.g., 0.01 wt.% to 25 wt.%, 0.01 wt.% to 20 wt.%, or 1 wt.% to 15 wt.% of a denaturant, and 50 wt.% to 99 wt.%, e.g., 60 wt.% to 99 wt.%, or 70 wt.% to 95 wt.% ethanol, based on the total weight of the denatured ethanol composition. Thus, by forming the denaturant in situ along with the ethanol in the hydrogenation step, the process of the present invention can produce denatured ethanol more efficiently and can reduce the number of processing steps. In particular, the process of the invention can eliminate the need to separately produce or obtain the denaturant and then add the denaturant to the ethanol.

In another embodiment, the invention relates to a process for producing denatured ethanol compositions, wherein the denaturant is formed by the hydrogenation of acetone, which may be added to the reaction zone or formed in situ as an intermediate as a by-product of the hydrogenation of acetic acid. In one aspect, for example, the method includes the step of contacting acetic acid with acetone to form an acetic acid reaction mixture. The process also includes hydrogenating the acetic acid reaction mixture in the presence of a catalyst to form a crude ethanol product comprising ethanol and isopropanol. In one embodiment, the acetone is formed in an auxiliary (auxiliary) acetone reactor or is obtained from an external source. Once formed or obtained, acetone may be contacted with acetic acid as described above. In another aspect, the catalyst or reaction conditions used in the hydrogenation reaction are selected such that acetone is formed as a byproduct of the acetic acid hydrogenation reaction. Once formed, the acetone intermediate may be hydrogenated to form an isopropanol denaturant. In these embodiments, ethanol is co-produced with an isopropanol denaturant. Preferably, the ethanol and isopropanol are produced in the same reactor. In one embodiment, the process of the present invention further comprises separating the caide ethanol product into a denatured ethanol composition and one or more derivative streams. The resulting denatured ethanol composition, as formed, comprises 0.01 wt.% to 10 wt.%, e.g., 0.01 wt.% to 5 wt.% or 0.01 wt.% to 3 wt.% isopropanol denaturant, and 50 wt.% to 99 wt.%, e.g., 60 wt.% to 99 wt.% or 70 wt.% to 95 wt.% ethanol, based on the total weight of the denatured ethanol composition.

The hydrogenation of acetic acid to ethanol and water can be represented by the following reaction:

suitable hydrogenation catalysts include catalysts comprising a first metal, optionally on a catalyst support, and optionally one or more of a second metal, a third metal, or an additional metal. The first and optional second and third metals may be selected from: IB. A transition metal of groups HB, IIIB, IVB, VB, VIB, VIIB, VIII, a lanthanide metal, an actinide metal or a metal selected from any of groups IIIA, IVA, VA and VIA. Preferred metal combinations for some exemplary catalyst compositions include platinum/tin, platinum/ruthenium, platinum/rhenium, palladium/ruthenium, palladium/rhenium, cobalt/palladium, cobalt/platinum, cobalt/chromium, cobalt/ruthenium, silver/palladium, copper/palladium, nickel/palladium, gold/palladium, ruthenium/rhenium, and ruthenium/iron. Exemplary catalysts are also described in U.S. patent nos. 7,608,744 and 7,863,489 and U.S. publication No.2010/0197485, which are incorporated herein by reference in their entirety.

In an exemplary 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, rhenium, molybdenum, and tungsten. 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 platinum and palladium. When the first metal comprises platinum, the catalyst preferably comprises platinum in an amount of less than 5 wt.%, for example less than 3 wt.% or less than 1 wt.%, due to the high demand for platinum.

As indicated above, the catalyst optionally further comprises a second metal, which may generally act as a promoter. The second metal, if present, is preferably selected from the group consisting of copper, molybdenum, tin, chromium, iron, cobalt, vanadium, tungsten, palladium, platinum, lanthanum, cerium, manganese, ruthenium, rhenium, gold, and nickel. More preferably, the second metal is selected from the group consisting of copper, tin, cobalt, rhenium, and nickel. More preferably, the second metal is selected from tin and rhenium.

If the catalyst comprises two or more metals, e.g., a first metal and a second metal, the first metal is optionally present in the catalyst in an amount of 0.1 wt.% to 10 wt.%, e.g., 0.1 wt.% to 5 wt.%, or 0.1 wt.% to 3 wt.%. The second metal is preferably present in an amount of 0.1 wt.% to 20 wt.%, e.g., 0.1 wt.% to 10 wt.% or 0.1 wt.% to 5 wt.%. For catalysts comprising two or more metals, the two or more metals may be alloyed with each other or may comprise a non-alloyed metal solid solution or mixture.

The preferred metal ratio may vary depending on the metal used in the catalyst. In some exemplary embodiments, the molar ratio of the first metal to the second metal is preferably from 10: 1 to 1: 10, such as from 4: 1 to 1: 4, 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 comprise a third metal selected from any of the metals listed above with respect to the first or second metal, provided that the third metal is different from the first and second metals. In a preferred aspect, the third metal is selected from the group consisting of cobalt, palladium, ruthenium, copper, zinc, platinum, tin, and rhenium. More preferably, the third metal is selected from cobalt, palladium and ruthenium. When present, the total weight of the third metal is preferably 0.05 wt.% to 4 wt.%, e.g., 0.1 to 3 wt.% or 0.1 wt.% to 2 wt.%.

Exemplary catalysts comprise, in addition to one or more metals, a support or a modified support, by which is meant a support comprising a support material and a support modifier which modulates the acidity of the support material. The total weight of the support or modified support is preferably 75 wt.% to 99.9 wt.%, e.g., 78 wt.% to 97 wt.% or 80 wt.% to 95 wt.%, based on the total weight of the catalyst. In preferred embodiments using a modified support, the support modifier is present in an amount from 0.1 wt.% to 50 wt.%, e.g., from 0.2 wt.% to 25 wt.%, from 0.5 wt.% to 15 wt.%, or from 1 wt.% to 8 wt.%, based on the total weight of the catalyst.

Suitable support materials may include, for example, a stable metal oxide-based support or a ceramic-based support. Preferred supports include siliceous supports such as silica, silica/alumina, group IIA silicates such as calcium metasilicate, pyrogenic silica, high purity silica and mixtures thereof. Other supports may include, but are not limited to, iron oxides (iron oxides), alumina, titania, zirconia, magnesia, carbon, graphite, high surface area graphitized carbon, activated carbon, and mixtures thereof.

In the production of ethanol, the catalyst support may be modified with a support modifier. Preferably, the support modifier is a basic modifier with low or no volatility. Such alkaline modifiers may be selected, for example, from: (i) alkaline earth metal oxides, (ii) alkali metal oxides, (iii) alkaline earth metal metasilicates, (iv) alkali metal metasilicates, (v) group IIB 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 including nitrates, nitrites, acetates, and lactates may be used. Preferably, the support modifier is selected from the group consisting of oxides and metasilicates of any of sodium, potassium, magnesium, calcium, scandium, yttrium, and zinc, and mixtures of any of the foregoing. Preferably, the support modifier is calcium silicate, more preferably calcium metasilicate (CaSiO)₃). If the support modifier comprises calcium metasilicate, at least a portion of the calcium metasilicate is preferably in crystalline form.

A preferred silica support material is a SS61138 High Surface Area (HSA) silica catalyst support from Saint Gobain NorPro. Saint-Gobain NorPro SS61138 silica contained about 95 wt.% high surface area silica; about 250m²Surface area per gram; a median pore diameter of about 12 nm; about 1.0cm as measured by mercury intrusion porosimetry³Average pore volume per gram and about 0.352g/cm³(22lb/ft³) The bulk density of (2).

A preferred silica/alumina support material is KA-160(Sud Chemie) silica spheres having a nominal diameter of about 5mm, a density of about 0.562g/ml, about 0.583g H₂Absorption rate of O/g carrier of about 160-175m²Surface area per gram and pore volume of about 0.68 ml/g.

Those skilled in the art will appreciate that the support material is selected such that the catalyst system has suitable activity, selectivity and robustness (robust) under the process conditions used to produce ethanol.

The metal of the catalyst may be dispersed throughout the support, coated on the outer surface of the support (egg shell) or modified (decoate) on the surface of the support.

Catalyst compositions suitable for use in the present invention are preferably formed by metal impregnation of the modified support, although other methods such as chemical vapor deposition may also be used. Such impregnation techniques are described in U.S. patent nos. 7,608,744 and 7,863,489 and U.S. publication No.2010/0197485, which are incorporated herein by reference in their entirety.

As will be readily appreciated by those skilled in the art, some embodiments of a process for hydrogenating acetic acid to form ethanol according to an embodiment of the present invention may include various configurations using fixed bed reactors or fluidized bed reactors. In many embodiments of the invention, an "adiabatic" reactor may be used; that is, there is little or no need for internal piping (plumbig) through the reaction zone to add or remove heat. In other embodiments, a radial flow reactor or reactors may be used, or a series of reactors with or without heat exchange, cooling, or introduction of additional feeds may be used. Alternatively, a shell-and-tube reactor provided with a heat transfer medium can be used. In many cases, the reaction zone may be housed in a single vessel or in a series of vessels with heat exchangers in between.

In a preferred embodiment, the catalyst is used in a fixed bed reactor, for example in the shape of a tube or conduit, through or otherwise through which the reactants, typically in vapor form, pass. Other reactors, such as fluidized bed or ebullated bed reactors, may be used. In some cases, the hydrogenation catalyst may be used in combination with an inert material to regulate 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 may be carried out in the liquid or gas phase. Preferably, the reaction is carried out in the gas phase under the following conditions. The reaction temperature may be from 125 ℃ to 350 ℃, e.g., from 200 ℃ to 325 ℃, from 225 ℃ to 300 ℃, or from 250 ℃ to 300 ℃. The pressure may be in the range of 10KPa to 3000KPa (about 1.5 to 435psi), for exampleSuch as 50KPa-2300KPa or 100KPa-1500 KPa. The reactants may be added for more than 500hr^-1E.g. greater than 1000hr^-1Greater than 2500hr^-1Or even greater than 5000hr^-1Is fed to the reactor at a Gas Hourly Space Velocity (GHSV). In terms of range, GHSV may be 50hr^-1-50,000hr^-1E.g. 500hr^-1-30,000hr^-1、1000hr^-1-10,000hr^-1Or 1000hr^-1-6500hr^-1。

Optionally, the hydrogenation is carried out at a selected GHSV at a pressure just sufficient to overcome the pressure drop across the catalytic bed, although the use of higher pressures is not limited, it being understood that at high space velocities, e.g., 5000hr^-1Or 6,500hr^-1May experience a significant pressure drop through the reactor bed.

Although the reaction consumes 2 moles of hydrogen per mole of acetic acid to produce 1 mole of ethanol, the actual molar ratio of hydrogen to acetic acid in the feed stream may be about 100: 1 to 1: 100, such as 50: 1 to 1: 50, 20: 1 to 1: 2, or 12: 1 to 1: 1. Most 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.

The contact or residence time may also vary widely depending on variables such as the amount of acetic acid, catalyst, reactor, temperature and pressure. Typical contact times range from fractions of a second to more than several hours when using a catalyst system other than a fixed bed, with preferred contact times, at least for gas phase reactions, of from 0.1 to 100 seconds, for example from 0.3 to 80 seconds or from 0.4 to 30 seconds.

The feedstock, acetic acid and hydrogen used in connection with the process of the present invention may be derived from any suitable source, including natural gas, petroleum, coal, biomass, and the like. By way of example, acetic acid may be produced by methanol carbonylation, acetaldehyde oxidation, ethylene oxidation, oxidative fermentation, and anaerobic fermentation. As petroleum and natural gas prices fluctuate, becoming more or less expensive, processes for the production of acetic acid and intermediates, such as methanol and carbon monoxide, from alternative carbon sources have become increasingly attractive. In particular, when petroleum is relatively expensive compared to natural gas, it may become advantageous to produce acetic acid from synthesis gas ("syngas") derived from any available carbon source. For example, U.S. patent No.6,232,352 (the disclosure of which is incorporated herein by reference) teaches a method of retrofitting a methanol plant to produce acetic acid. By retrofitting a methanol plant, the substantial capital costs associated with carbon monoxide production are significantly reduced or largely eliminated for the new acetic acid plant. All or a portion of the syngas is diverted from the methanol synthesis loop and fed to a separator unit to recover carbon monoxide and hydrogen, which are then used to produce acetic acid. In addition to acetic acid, this process can also be used to produce hydrogen that can be utilized in connection with the present invention.

Methanol carbonylation processes suitable for the production of acetic acid are described in U.S. Pat. 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 disclosures of which are incorporated herein by reference. Optionally, ethanol production may be integrated with such a methanol carbonylation process.

U.S. patent No. re 35,377 (also incorporated herein by reference) provides a method for producing methanol by converting carbonaceous materials such as oil, coal, natural gas, and biomass materials. The method comprises hydro-gasification of solid and/or liquid carbonaceous material to obtain a process gas, which process gas is steam pyrolyzed with additional natural gas to form synthesis gas. The synthesis gas is converted to methanol which can be carbonylated to acetic acid. This process also produces hydrogen gas as described above in connection with the present invention. U.S. Pat. No.5,821,111 and U.S. Pat. No.6,685,754, the disclosures of which are incorporated herein by reference, disclose a process for converting waste biomass to syngas via gasification.

In an optional embodiment, the acetic acid feed stream to the hydrogenation reaction comprises acetic acid and may also comprise other carboxylic acids (e.g., propionic acid), esters, and anhydrides, as well as acetaldehyde and acetone. In one embodiment, the acetic acid fed to the hydrogenation reaction comprises propionic acid. For example, propionic acid in the acetic acid feed stream can be 0.001 wt.% to 15 wt.%, e.g., 0.001 wt.% to 0.11 wt.%, 0.125 wt.% to 12.5 wt.%, 1.25 wt.% to 11.25, or 3.75 wt.% to 8.75 wt.%. Thus, the acetic acid feed stream may be a crude (cruder) acetic acid feed stream, such as a less refined acetic acid feed stream. In these embodiments, propionic acid in the acetic acid feed stream is hydrogenated to form n-propanol, which may act as a denaturant. N-propanol may be present in the denatured ethanol composition in an amount from 0.001 wt.% to 15 wt.%, e.g., from 0.001 wt.% to 0.11 wt.%, from 0.13 wt.% to 13.2 wt.%, from 1.3 wt.% to 11.9 wt.%, or from 4 wt.% to 9.3 wt.%.

Alternatively, acetic acid in vapor form may be withdrawn as a crude product directly from the flasher of a methanol carbonylation unit of the type described in U.S. Pat. No.6,657,078, incorporated herein by reference in its entirety. For example, the crude vapor product can be fed directly to the ethanol synthesis reaction zone of the present invention without the need to condense acetic acid and light ends or remove water, thereby saving overall process costs.

In one embodiment, acetone is added to the reactor as a reactant in addition to acetic acid and hydrogen. Without being bound by theory, it is believed that the addition of acetone to the reaction produces isopropanol, which may act as a denaturant. In another aspect, acetone is formed as a byproduct of the hydrogenation of acetic acid. Once formed, the acetone may be hydrogenated to form isopropanol as a denaturant. In some embodiments, when an isopropanol denaturant is desired, a separate catalyst may be used to produce higher concentrations of acetone, which upon subsequent hydrogenation may produce higher concentrations of isopropanol in the crude ethanol composition. As an example, a support comprising, for example, TiO may be used₂、ZrO₂、Fe₂O₃Or CeO₂The catalyst composition of (1). Other exemplary catalyst compositions include SiO₂Supported ruthenium, carbon supported iron, or carbon supported palladium.

In one embodiment, the acetone is formed in a secondary reaction carried out in a secondary acetone reactor. As an example, acetic acid may be reacted in a secondary reactor under conditions effective to form acetone, such as ketonization. The acetic acid fed to the auxiliary reactor may be taken from the acetic acid feed stream fed to the hydrogenation reactor. The auxiliary reactor may be of the type discussed above. For example, the auxiliary reactor may be a fixed bed reactor in which the catalyst is located. Preferably, the secondary reactor is in the shape of a tube or conduit through which the reactants (typically in the form of vapors) pass or pass over a catalyst located in the tube or conduit. In some embodiments, the secondary reactor uses a catalyst that promotes ketonization and/or aids in the production of acetone. As an example, the catalyst may comprise a basic catalyst, such as thorium oxide. In some embodiments, the acetone produced by the auxiliary reactor is directed to the hydrogenation reactor as a reactant in addition to acetic acid and hydrogen.

The acetic acid may be vaporized at the reaction temperature, and the vaporized acetic acid may then be fed along with hydrogen in an undiluted state or diluted with a relatively inert carrier gas such as nitrogen, argon, helium, carbon dioxide, and the like. For the reaction to run in the gas phase, the temperature in the system should be controlled so that it does not fall below the dew point of acetic acid. In one embodiment, the acetic acid may be vaporized at the boiling point of acetic acid at a specific pressure, and then the vaporized acetic acid may be further heated to the reactor inlet temperature. In another embodiment, acetic acid is converted to a vapor state by passing hydrogen, recycle gas, another suitable gas, or a mixture thereof through acetic acid at a temperature below the boiling point of acetic acid, thereby wetting the carrier gas with acetic acid vapor, followed by heating the mixed vapor up to the reactor inlet temperature. Preferably, the acetic acid is converted to a vapor by passing hydrogen and/or recycle gas through the acetic acid at a temperature at or below 125 ℃, followed by heating the combined gaseous stream to the reactor inlet temperature.

In particular, the hydrogenation of acetic acid may result in a favorable conversion of acetic acid and a favorable selectivity and yield to ethanol. For the purposes of the present invention, the term "conversion" refers to the amount of acetic acid in the feed that is converted to compounds other than acetic acid. Conversion is expressed as a mole percent based on acetic acid in the feed. The conversion may be at least 10%, for example at least 20%, at least 40%, at least 50%, at least 60%, at least 70% or at least 80%. While catalysts with high conversion, e.g., at least 80% or at least 90%, are desirable, in some embodiments low conversions may be acceptable when the selectivity to ethanol is high. It is, of course, well understood that in many cases conversion can be compensated for by appropriate recycle streams or by using larger reactors, but it is more difficult to compensate for poor selectivity.

Selectivity is expressed as mole percent based on converted acetic acid. It is understood that each compound converted from acetic acid has an independent selectivity and that the selectivity is independent of conversion. For example, if 50 mole% of the converted acetic acid is converted to ethanol, the ethanol selectivity is 50%. Preferably, the catalyst selectivity to ethoxylate is at least 60%, for example at least 70% or at least 80%. As used herein, the term "ethoxylate" refers specifically to the compounds ethanol, acetaldehyde and ethyl acetate. Preferably, the selectivity to ethanol is at least 80%, such as at least 85% or at least 88%. Preferred embodiments of the hydrogenation process also have low selectivity to undesirable products such as methane, ethane, and carbon dioxide. The selectivity to these undesired products is preferably less than 4%, for example less than 2% or less than 1%. More preferably, these undesired products are not detectable. Formation of alkanes may be low, and ideally less than 2%, less than 1%, or less than 0.5% of the acetic acid passing through the catalyst is converted to alkanes, which have little value other than as fuel.

The term "yield" as used herein refers to the grams of a given product, e.g., ethanol, formed per hour during hydrogenation based on the kilograms of catalyst used. Preferably, the yield of ethanol per kilogram catalyst per hour is at least 200 grams, such as at least 400 grams or at least 600 grams. In terms of ranges, the yield is preferably 200-.

In various embodiments, the crude ethanol product produced by the hydrogenation process will typically comprise unreacted acetic acid, ethanol, and water prior to any subsequent processing, such as purification and isolation. As used herein, the term "crude ethanol product" refers to any composition comprising 5 wt.% to 70 wt.% ethanol and 5 wt.% to 35 wt.% water. In some exemplary embodiments, the caide ethanol product comprises ethanol in an amount of 5 wt.% to 70 wt.%, e.g., 10 wt.% to 60 wt.% or 15 wt.% to 50 wt.%, based on the total weight of the caide ethanol product. Preferably, the caide ethanol product comprises at least 10 wt.% ethanol, at least 15 wt.% ethanol, or at least 20 wt.% ethanol.

Depending on the conversion, the caide ethanol product typically will also contain unreacted acetic acid, for example in an amount of less than 90 wt.%, e.g., less than 80 wt.%, or less than 70 wt.%. In terms of ranges, unreacted acetic acid is preferably present in an amount of 0 wt.% to 90 wt.%, e.g., 5 wt.% to 80 wt.%, 15 wt.% to 70 wt.%, 20 wt.% to 70 wt.%, or 25 wt.% to 65 wt.%. When acetone is included as a reactant, the caide ethanol product may comprise from 0.01 wt.% to 10 wt.%, e.g., from 0.1 wt.% to 10 wt.%, from 1 wt.% to 9 wt.%, or from 3 wt.% to 7 wt.% isopropanol. In other embodiments, the crude ethanol product comprises from 0.01 wt.% to 20 wt.%, e.g., from 0.1 wt.% to 10 wt.%, from 1 wt.% to 9 wt.%, or from 3 wt.% to 7 wt.% diethyl ether. Because water is formed during the reaction, the caide ethanol product typically comprises water in an amount of, for example, 5 to 35 wt.%, such as 10 to 30 wt.% or 10 to 26 wt.%. Ethyl acetate may also be produced during the hydrogenation of acetic acid or by side reactions. In these embodiments, the caide ethanol product comprises ethyl acetate in an amount of 0 to 20 wt.%, e.g., 0 to 15 wt.%, 1 to 12 wt.%, or 3 to 10 wt.%. Acetaldehyde may also be produced by side reactions. In these embodiments, the caide ethanol product comprises acetaldehyde in an amount from 0 to 10 wt.%, e.g., from 0 to 3 wt.%, from 0.1 to 3 wt.%, or from 0.2 to 2 wt.%. In some embodiments in which propionic acid is included as a reactant, the n-propanol formed by the hydrogenation can be present in the crude ethanol product in an amount from 0.001 wt.% to 15 wt.%, e.g., from 0.001 wt.% to 0.11 wt.%, from 0.13 wt.% to 13.2 wt.%, from 1.3 wt.% to 11.9 wt.%, or from 4 wt.% to 9.3 wt.%.

Thus, the hydrogenation reaction produces a crude ethanol product that may include, inter alia, denaturants such as acetic acid, isopropanol, ethyl acetate, diethyl ether, acetaldehyde, and/or n-propanol. Each of these in situ formed compounds (alone or in combination with one another) can act as a denaturant in the denatured ethanol composition. In some embodiments, all or a portion of the crude ethanol product may be combined with a purified ethanol stream to form a denatured ethanol composition. It is within the scope of the present invention to adjust the reaction parameters to obtain the desired crude ethanol product and thus the desired denatured ethanol composition. In one embodiment, the amount of reactants, e.g., acetic acid, acetone, and/or propionic acid, etc., fed to the hydrogenation reactor can be adjusted to obtain a specific amount of one or more components, e.g., denaturants, in the caide ethanol product. The denaturant so produced may be combined with the purified ethanol stream to form a denatured ethanol composition. For example, a denatured ethanol composition comprising about 5 parts isopropanol to 100 parts ethanol may be produced by feeding an acetic acid stream comprising acetic acid and acetone. As another example, a denatured ethanol composition comprising about 5 parts n-propanol to 100 parts ethanol may be produced by feeding an acetic acid stream comprising acetic acid and propionic acid. It is also within the scope of the present invention to adjust the parameters of the additional hydrogenation reactor to obtain a crude ethanol product comprising a desired amount of a particular denaturant or combination of denaturants. For example, to produce a crude ethanol product comprising about 10 parts Diethyl Ether, a hydrogenation catalyst having an acidic support may be used as described in co-pending U.S. application No.12/850,414 entitled "Processes for Making Diethyl Ether from Acetic Acid," filed on 8/4 2010 (the entire contents and disclosure of which are incorporated herein by reference).

In one embodiment, because it is difficult to separate isopropanol and ethanol from each other, all or a portion of the isopropanol formed in the hydrogenation reaction may follow the ethanol through a separation scheme (scheme).

Because the crude ethanol composition, as formed, may contain the denaturant formed in situ, at least a portion of the crude ethanol composition may be combined with the purified ethanol stream, with or without further separation, to form a denatured ethanol composition. In one embodiment, one or more in situ formed denaturants may be separated from the crude ethanol product and combined with the purified ethanol stream. In other embodiments, at least a portion (e.g., an aliquot) of the crude ethanol product may be combined with the purified ethanol stream. For example, when the crude ethanol product comprises n-propanol, at least a portion of the crude ethanol product comprising n-propanol can be combined with a purified ethanol stream to form a denatured ethanol composition comprising an n-propanol denaturant. In another embodiment, at least a portion of the n-propanol is separated from the crude ethanol product and combined with the purified ethanol stream to form an n-propanol denatured ethanol composition. As another example, when acetic acid is the desired denaturant, at least a portion of the crude ethanol composition containing acetic acid may be combined with the purified ethanol stream to form a denatured ethanol composition comprising the acetic acid denaturant. In another embodiment, at least a portion of the acetic acid in the acetic acid feed and/or in any acetic acid recycle stream may be combined with the purified ethanol stream to form an acetodenatured ethanol composition.

Other components such as esters, ethers, aldehydes, ketones, alkanes, and carbon dioxide, if detectable, may be present in total in an amount of less than 10 wt.%, e.g., less than 6 wt.% or less than 4 wt.%. In terms of ranges, the caide ethanol composition may include other components in an amount from 0.1 wt.% to 10 wt.%, e.g., from 0.1 wt.% to 6 wt.% or from 0.1 wt.% to 4 wt.%. Exemplary embodiments of crude ethanol composition ranges are provided in table 1.

As shown in table 1, in some embodiments, the crude ethanol product may be a denatured ethanol composition. For example, the caide ethanol composition may comprise ethanol and at least one denaturant such as acetic acid, ethyl acetate, or acetaldehyde. In other embodiments, the crude ethanol composition may be a denatured ethanol composition comprising at least one of the denaturants described above.

Fig. 1A shows a hydrogenation system 100 suitable for the hydrogenation of acetic acid and the separation of ethanol from a crude reaction mixture, according to one embodiment of the invention. System 100 comprises a reaction zone 101 and a distillation zone 102. Reaction zone 101 comprises reactor 103, hydrogen feed line 104, and acetic acid feed line 105. In other embodiments, when acetone is used as a reactant, reaction zone 101 further comprises an acetone feed line (not shown). In other embodiments, when propionic acid is used as a reactant, reaction zone 101 further comprises a propionic acid feed line (not shown). Distillation zone 102 comprises flasher 106, first column 107, second column 108, and third column 109. Hydrogen, acetic acid and optionally acetone and/or propionic acid are fed via lines 104 and 105 to evaporator 110 to produce a vapor feed stream in line 111 directed to reactor 103. In one embodiment, lines 104 and 105 can be combined and co-fed to evaporator 110, for example, in one stream containing hydrogen and acetic acid. The temperature of the vapor feed stream in line 111 is preferably from 100 ℃ to 350 ℃, e.g., from 120 ℃ to 310 ℃ or from 150 ℃ to 300 ℃. As shown in FIG. 1A, any feed that is not vaporized is removed from evaporator 110 and may be recycled thereto. Further, while fig. 1A shows line 111 directed to the top of reactor 103, line 111 may be directed to the side, top, or bottom of reactor 103. Although one reactor and one flasher are shown in fig. 1A, 1B, and 1C, additional reactors and/or components may be included in various alternative embodiments of the present invention. For example, the hydrogenation system may optionally comprise a dual reactor, a dual flasher, a heat exchanger, and/or a preheater.

Reactor 103 contains a catalyst for hydrogenating carboxylic acid, preferably acetic acid. In some embodiments where acetone is the reactant and isopropanol is the desired co-product with ethanol, the catalyst in reactor 103 is selected so that isopropanol is produced in addition to ethanol. As an example, a support comprising, for example, TiO may be used₂、ZrO₂、Fe₂O₃Or CeO₂The catalyst composition of (1). In some embodiments, these catalysts promote higher acetone formation (formation). Other exemplary catalyst compositions include SiO₂Supported ruthenium, carbon supported iron, or carbon supported palladium. In other embodiments, can regulateThe temperature of reactor 103 to achieve the desired isopropanol concentration. For example, maintaining the reaction temperature in the range of 200 ℃ to 350 ℃, e.g., 225 ℃ to 300 ℃, can result in an ethanol composition comprising 0.1 wt.% to 10 wt.%, e.g., 1 wt.% to 9 wt.% or 3 wt.% to 7 wt.% isopropanol. In one embodiment, one or more guard beds (not shown) may be used to protect the catalyst from toxic materials or undesirable impurities contained in the feed or return/recycle streams. Such guard beds may be used in vapor streams or liquid streams. Suitable guard bed materials are known in the art and include, for example, carbon, silica, alumina, ceramics or resins. In one aspect, the guard bed media is functionalized to trap a particular species such as sulfur or halogen. During the hydrogenation process, a crude ethanol product stream is preferably continuously withdrawn from reactor 103 via line 112. The caide ethanol product stream may be condensed and fed to flasher 106, which in turn provides a vapor stream and a liquid stream. In one embodiment, the flash vessel 106 is preferably operated at a temperature of from 50 ℃ to 500 ℃, e.g., from 70 ℃ to 400 ℃ or from 100 ℃ to 350 ℃. In one embodiment, the pressure in flash vessel 106 is preferably from 50KPa to 2000KPa, for example from 75KPa to 1500KPa or 100 and 1000 KPa. In a preferred embodiment, the temperature and pressure of the flasher are similar to the temperature and pressure of reactor 103.

The vapor stream exiting flasher 106 can comprise hydrogen and hydrocarbons, which can be purged and/or returned to reaction zone 101 via line 113. As shown in fig. 1A, the returned portion of the vapor stream passes through compressor 114 and is combined with the hydrogen feed and co-fed to evaporator 110.

Liquid from flasher 106 is withdrawn and pumped as a feed composition through line 115 to the side of first column 107 (also referred to as an acid separation column). The contents of line 115 will typically be substantially similar to the product obtained directly from the reactor, and may in fact also be referred to as a caide ethanol product. However, the feed composition in line 115 is preferably substantially free of hydrogen, carbon dioxide, methane, or ethane, which are removed by flasher 106. Exemplary compositions of the liquid in line 115 are provided in table 2. It is understood that the liquid line 115 may contain other components (not listed), such as components in the feed.

Amounts less than (<) indicated in the tables throughout this application are preferably absent and if present may be present in trace amounts or in amounts greater than 0.0001 wt.%.

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 mixtures thereof. The "other ethers" in Table 2 may include, but are not limited to, diethyl ether, methyl ethyl ether, isobutyl ethyl ether, or mixtures thereof. The "other alcohols" in table 2 may include, but are not limited to, methanol, isopropanol, n-propanol, n-butanol, or mixtures thereof. In an embodiment, the feed composition, such as line 115, can advantageously comprise a small amount, such as from 0.001 wt.% to 0.1 wt.%, from 0.001 wt.% to 0.05 wt.%, or from 0.001 wt.% to 0.03 wt.% of a propanol, such as isopropanol and/or n-propanol. Due to these low concentrations of alcohol, the resulting denatured ethanol composition advantageously contains only trace amounts (if any) of the alcohol (see discussion below). These traces are significantly lower than those levels obtained by processes that do not use acetic acid hydrogenation. In other embodiments, the concentration of isopropanol in the feed composition is higher, e.g., from 0.01 to 10 wt.%. In other embodiments, the concentration of n-propanol in the feed composition is higher, e.g., from 0.01 to 10 wt.%. In other embodiments, the concentration of diethyl ether in the feed composition is higher, e.g., from 0.01 to 20 wt.%. It is to be understood that these other components may be carried in any of the distillate or residue streams described herein. Furthermore, as indicated above, some of these other components, such as isopropanol or diethyl ether, may also be used as denaturants.

When the content of acetic acid in line 115 is less than 5 wt.%, acid separation column 107 can be bypassed and line 115 can be introduced directly to second column 108 (also referred to herein as the light ends column).

In the embodiment shown in fig. 1A, line 115 is introduced into the lower portion, e.g., the lower half or the lower third, of the first column 107. In the first column 107, unreacted acetic acid, a portion of the water, and other heavy components (if present) are removed from the composition in line 115 and preferably continuously withdrawn as a residue. Some or all of the residue can be returned and/or recycled back to reaction zone 101 via line 116. The first column 107 also forms an overhead which is withdrawn in line 117 and may be condensed and refluxed, for example, in a ratio of from 10: 1 to 1: 10, such as from 3: 1 to 1: 3 or from 1: 2 to 2: 1.

Any of columns 107, 108 or 109 may comprise any distillation column capable of separation and/or purification. The column preferably comprises a tray column having from 1 to 150 trays, for example from 10 to 100 trays, from 20 to 95 trays or from 30 to 75 trays. The trays may be sieve trays, fixed valve trays, moving valve trays, or any other suitable design known in the art. In other embodiments, a packed column may be used. For packed columns, structured packing or random packing may be used. The columns or packing may be arranged in one continuous column or they may be arranged in two or more columns so that vapor from the first section enters the second section while liquid from the second section enters the first section, and so on.

The associated condensers and liquid separation vessels that may be used with the various distillation columns may be of any conventional design and are simplified in fig. 1A, 1B and 1C. As shown in fig. 1A, 1B and 1C, heat can be supplied to the bottom of each column or to the circulating bottoms stream through a heat exchanger or reboiler. In some embodiments, other types of reboilers, such as internal reboilers, may also be used. The heat provided to the reboiler may be derived from any heat generated during a process integrated with the reboiler or from an external source such as another heat generating chemical process or a boiler. Although one reactor and one flasher are shown in fig. 1A, 1B, and 1C, additional reactors, flashers, condensers, heating elements, and other components may be used in embodiments of the invention. As will be appreciated by those skilled in the art, the various condensers, pumps, compressors, reboilers, drums, valves, connectors, disengaging vessels, etc., typically used to perform chemical processes may also be combined and used in the process of the present invention.

The temperature and pressure used in any column can vary. As a practical matter, pressures of 10KPa to 3000KPa may typically be used in these regions, although subatmospheric pressures as well as superatmospheric pressures may be used in some embodiments. The temperature within each zone will generally be in the range between the boiling point of the composition removed as distillate and the boiling point of the composition removed as residue. Those skilled in the art will recognize that the temperature at a given location in an operating distillation column depends on the composition of the feed at that location and the pressure of the column. Further, the feed rate may vary depending on the scale of the production process, and if described, may generally refer to the feed weight ratio.

When column 107 is operated at standard atmospheric pressure, the temperature of the residue exiting column 107 in line 116 is preferably from 95 ℃ to 120 ℃, e.g., from 105 ℃ to 117 ℃ or from 110 ℃ to 115 ℃. The temperature of the distillate exiting from column 107 in line 117 is preferably from 70 ℃ to 110 ℃, e.g., from 75 ℃ to 95 ℃ or from 80 ℃ to 90 ℃. In other embodiments, the pressure of the first column 107 can be from 0.1KPa to 510KPa, for example from 1KPa to 475KPa or from 1KPa to 375 KPa. Exemplary components of the distillate and residue compositions of first column 107 are provided in table 3 below. It should also be understood that the distillate and residue may also contain other components not listed, such as components in the feed. For convenience, the distillate and residue of the first column may also be referred to as "first distillate" or "first residue". The distillates or residues of other columns may also be referred to by similar numerical modifiers (second, third, etc.) in order to distinguish them from one another, but such modifiers should not be construed as requiring any particular order of separation.

As shown in table 3, while not being bound by theory, it was unexpectedly and unexpectedly found that when any amount of acetal is detected in the feed introduced to the acid separation column (first column 107), the acetal appears to decompose in that column such that there is less or even no detectable amount in the distillate and/or residue.

Depending on the reaction conditions, the caide ethanol product exiting reactor 103 in line 112 can comprise ethanol, acetic acid (unconverted), ethyl acetate, and water. After exiting reactor 103, a non-catalytic equilibrium reaction may occur between the components contained in the caide ethanol product prior to being fed to flasher 106 and/or first column 107. As shown below, this equilibrium reaction tends to drive the caide ethanol product to an equilibrium between ethanol/acetic acid and ethyl acetate/water.

Extended residence times may be encountered in situations where the crude ethanol product is temporarily stored, for example, in a holding tank, prior to being directed to distillation zone 102. Generally, the longer the residence time between reaction zone 101 and distillation zone 102, the more ethyl acetate is formed. For example, when the residence time between the reaction zone 101 and the distillation zone 102 is greater than 5 days, significantly more ethyl acetate is formed with loss of ethanol. Therefore, a shorter residence time between the reaction zone 101 and the distillation zone 102 is generally preferred to maximize the amount of ethanol formed. In one embodiment, a storage tank (not shown) is included between reaction zone 101 and distillation zone 102 for temporarily storing the liquid component from line 115 for up to 5 days, such as up to 1 day or up to 1 hour. In a preferred embodiment, no tank is included and the condensed liquid is fed directly to the first distillation column 107. In addition, the rate at which the non-catalytic reaction proceeds can increase as the temperature of the caide ethanol product, for example, in line 115, increases. These reaction rates can be particularly problematic at temperatures in excess of 30 ℃, e.g., in excess of 40 ℃ or in excess of 50 ℃. Thus, in one embodiment, the temperature of the liquid component in line 115 or in an optional storage tank is maintained at a temperature of less than 40 ℃, e.g., less than 30 ℃ or less than 20 ℃. One or more cooling devices may be used to reduce the temperature of the liquid in line 115.

As discussed above, a storage tank (not shown) may be included between reaction zone 101 and distillation zone 102 for temporarily storing liquid components from line 115, optionally at a temperature of about 21 ℃, for example 1-24 hours, and corresponding to 0.01 wt.% to 1.0 wt.% ethyl acetate formation, respectively. In addition, the rate at which the non-catalytic reaction proceeds may increase as the temperature of the caide ethanol product increases. For example, as the crude ethanol product temperature in line 115 increases from 4 ℃ to 21 ℃, the rate of ethyl acetate formation can increase from about 0.01 wt.%/hour to about 0.005 wt.%/hour. Thus, in one embodiment, the temperature of the liquid component in line 115 or in an optional storage tank is maintained at a temperature of less than 21 ℃, e.g., less than 4 ℃ or less than-10 ℃.

Furthermore, it has been found that the above equilibrium reaction may also promote the formation of ethanol in the top region of the first column 107.

As shown in FIGS. 1A-C, the distillate from column 107, e.g., the overhead stream, is optionally condensed and preferably refluxed at a reflux ratio of from 1: 5 to 10: 1. The distillate in line 117 preferably comprises ethanol; in situ denaturants such as ethyl acetate and/or acetaldehyde; water, and other impurities, which can be difficult to separate due to the formation of binary and ternary azeotropes. The first distillate also comprises a significantly reduced amount of acetic acid. As shown in fig. 1C, in some embodiments, the distillate of the first column (not further treated) is a denatured ethanol composition comprising 0.0001 wt.% to 80 wt.%, e.g., 0.001 wt.% to 60 wt.% denaturant, and 20 wt.% to 75 wt.%, e.g., 30 wt.% to 70 wt.% ethanol. Preferably, in these embodiments the denaturant is ethyl acetate. In other embodiments, the distillate of the first column (not further treated) is a denatured ethanol composition comprising 0.0001 wt.% to 10 wt.%, e.g., 0.001 wt.% to 5 wt.% or 0.01 wt.% to 4 wt.% of a denaturant, and 20 wt.% to 75 wt.%, e.g., 30 wt.% to 70 wt.% ethanol. Preferably, the denaturant in these embodiments is acetaldehyde.

In another embodiment, at least a portion of the first distillate can be combined with a purified ethanol stream via optional line 117' to form a denatured ethanol composition. Preferably, the denaturant comprises ethyl acetate and/or acetaldehyde. In another embodiment, at least a portion of the first distillate can be fed to an additional column, such as a third column as discussed below. As a result, denaturants such as ethyl acetate and/or acetaldehyde in the first distillate may be carried over to the distillate of the third column. As such, the third distillate may be a denatured ethanol composition comprising the denaturant from the first distillate. In these embodiments, the weight percent of denaturant in the denatured ethanol composition may be as discussed previously. The weight ratio of the denaturant-containing stream, such as line 117, to the purified ethanol stream varies widely and can be adjusted to achieve a particular desired concentration of denaturant in the denatured ethanol composition. For example, the weight ratio of the purified ethanol stream to the denaturant-containing stream can be from 0.01: 1 to 5: 1, such as from 0.05: 1 to 3: 1.

As discussed above, the residue from the first column 107 includes an amount of unreacted acetic acid. Thus, in another embodiment, at least a portion of the first residue can be combined with a purified ethanol stream to form an acetogenic ethanol composition.

Advantageously, these denatured ethanol compositions are produced using denaturants formed in situ by hydrogenation reactions and without additional separation steps. As such, it is not necessary to provide an additional external source of denaturant or combine denaturant with purified ethanol, which cuts down on process steps and simplifies the overall process. It is also within the scope of the invention to further purify the first column distillate to remove, for example, additional water and/or acetaldehyde. Such additional purification can be achieved using conventional separation methods.

As shown in table 3, the first residue comprises a significant portion of unreacted acetic acid, which may in turn be recycled back to the reactor 103 as shown in fig. 1A, 1B, and 1C.

The first distillate in line 117 is introduced to the second column 108 (also referred to as the "light ends column"), preferably in a middle portion, e.g., the middle half or middle third, of column 108. Second column 108 can be a tray column or a packed column. In one embodiment, the second column 108 is a tray column having 5 to 70 trays, such as 15 to 50 trays or 20 to 45 trays.

As an example, line 117 is introduced at tray 17 when a 25 tray column is used in a column without water stripping. When the second column is not an extractive distillation column, it is desirable that the ethyl acetate in line 117 can be separated into a second residue along with ethanol and water. As a result, in one embodiment, more ethyl acetate may be fed to third column 109, and thus, the ethyl acetate may be present in the third distillate. In other embodiments, at least a portion of the second residue comprising ethyl acetate can be combined with a purified ethanol stream to form a denatured ethanol composition.

However, in a preferred embodiment, the second column 108 may be an extractive distillation column. In the extractive distillation column, the ethyl acetate in line 117 can desirably be separated from the ethanol and water and passed into the second distillate. In such embodiments, an extractive agent, such as water, can optionally be added to the second column 108 via line 127. If the extractant comprises water, it may be obtained from an external source or from an internal return/recycle line from one or more other columns. In a preferred embodiment, water in the third residue of the third column 109 is utilized as the extractant. As shown in fig. 1A, 1B, and 1C, the third residue can optionally be directed to second column 108 via line 121'.

While the temperature and pressure of second column 108 can vary, the temperature of the second residue exiting second column 108 in line 118 when at atmospheric pressure is preferably from 60 ℃ to 90 ℃, e.g., from 70 ℃ to 90 ℃ or from 80 ℃ to 90 ℃. The temperature of the second distillate exiting second column 108 in line 120 is preferably from 50 ℃ to 90 ℃, e.g., from 60 ℃ to 80 ℃ or from 60 ℃ to 70 ℃. Column 108 may be operated at atmospheric pressure. In other embodiments, the pressure of the second column 108 can be from 0.1KPa to 510KPa, such as from 1KPa to 475KPa or from 1KPa to 375 KPa. Exemplary components of the distillate and residue compositions of second column 108 are provided in table 4 below. It is understood that the distillate and residue may also contain other components not listed, such as components in the feed.

The weight ratio of ethanol in the second residue to ethanol in the second distillate is preferably at least 3: 1, such as at least 6: 1, at least 8: 1, at least 10: 1, or at least 15: 1. The weight ratio of ethyl acetate in the second residue to ethyl acetate in the second distillate is preferably less than 0.4: 1, for example less than 0.2: 1 or less than 0.1: 1. In embodiments where an extraction column using water as the extractant is used as second column 108, the weight ratio of ethyl acetate in the second residue to ethyl acetate in the second distillate is near zero. Thus, as shown in table 4, the second distillate in line 120 (which is a derivative stream of the caide ethanol product) comprises a significant amount of the in situ-separated denaturant, and the second residue in line 118 comprises a significant amount of ethanol. In some embodiments, the second distillate comprises diethyl ether. The diethyl ether may be present in an amount of 0.1 wt.% to 20 wt.%, e.g., 0.1 wt.% to 10 wt.%, 1 wt.% to 9 wt.%, or 3 wt.% to 7 wt.%. In these cases, the second distillate may be a denatured ethanol composition with a diethyl ether denaturant. In one embodiment, the second residue in line 118 further comprises isopropanol. Isopropanol may be derived from acetone by the methods described above. The acetone may be formed in situ in the hydrogenation, for example, and/or may be added to the hydrogenation reactor as a reactant. Thus, in embodiments in which a sufficient amount, e.g., 0.1 wt.% to 10 wt.%, 1 wt.% to 9 wt.%, or 3 wt.% to 7 wt.% of isopropanol, is present in the second residue, the second residue may be a denatured ethanol composition having an isopropanol denaturant.

In another embodiment of the invention as shown in fig. 1A, at least a portion of the second distillate is directed to the purified ethanol exiting third column 109, e.g., via line 120. In this case, the denatured ethanol composition results from the addition of the in situ formed denaturant to the purified ethanol. Preferably, the ethyl acetate denaturant in the second distillate is combined with the purified ethanol obtained from third column 109. In other embodiments, the acetaldehyde denaturant in the second distillate is combined with the purified ethanol obtained from third column 109. In other embodiments, at least a portion of the second distillate is fed to third column 109. In these cases, at least a portion of the denaturant, e.g., ethyl acetate and/or acetaldehyde, in the second distillate is passed to the third column 109 following the ethanol. Other impurities in the second distillate may be withdrawn in the residue of third column 109. As a result, the third distillate contains ethanol along with the denaturant from the second column distillate. The denatured ethanol composition so formed may have the characteristics and compositions of denatured ethanol compositions discussed herein. The weight ratio of the denaturant-containing stream, such as line 120, to the purified ethanol stream varies widely and can be adjusted to achieve a particular desired concentration of denaturant in the denatured ethanol composition. For example, when ethyl acetate is the denaturant, the weight ratio of the purified ethanol stream to the denaturant-containing stream can be from 100: 1 to 1: 1, such as from 25: 1 to 5: 1.

In another embodiment, at least a portion of the second distillate is recycled to reactor 103 (not shown). As shown, the second residue from the bottom of second column 108, which comprises ethanol and water, is fed to third column 109 (also referred to as the "product column") via line 118. More preferably, the second residue in line 118 is introduced into a lower portion, e.g., the lower half or the lower third, of the third column 109. The third column 109 recovers ethanol (preferably substantially pure except for the azeotropic water content) as a distillate in line 119. The distillate of the third column 109 is preferably refluxed as shown in FIG. 1A, for example at a reflux ratio of from 1: 10 to 10: 1, such as from 1: 3 to 3: 1 or from 1: 2 to 2: 1. The third residue in line 121, preferably comprising primarily water, is preferably removed from the system 100 or may be partially returned to any portion of the system 100. The third column 109 is preferably a tray column as described above and is preferably operated at atmospheric pressure. The temperature of the third distillate exiting from third column 109 in line 119 is preferably from 60 ℃ to 110 ℃, e.g., from 70 ℃ to 100 ℃ or from 75 ℃ to 95 ℃. When the column is operated at atmospheric pressure, the temperature of the third residue leaving the third column 109 is preferably in the range of from 70 ℃ to 115 ℃, for example from 80 ℃ to 110 ℃ or from 85 ℃ to 105 ℃. Exemplary components of the distillate, residue, and optional side stream composition of third column 109 are provided in table 5 below. As shown in table 5, the third distillate may contain a significant amount of isopropanol denaturant. In these cases, the third distillate may be a denatured ethanol composition. It is understood that the distillate and residue may also contain other components not listed, such as components in the feed.

As a result of the separation in the third column, the composition of the stream subjected to separation can vary from tray to tray in the third column. In some embodiments, the composition of the stream within the third column (depending on the operating conditions) may contain an increased concentration or build-up of alcohol, for example, mid-boiling alcohol having a boiling point below water and above the mid-boiling point of the ethanol/water low boiling azeotrope. Examples of these alcohols include n-propanol (BP 97.1 ℃ C.), isopropanol (BP 82.5 ℃ C.) and 2-butanol (BP 99.5 ℃ C.). Some of these alcohols are formed in situ from the hydrogenation of acetic acid. Preferably, these in situ formed intermediate boiling alcohols can be used as denaturants.

One or more side streams 138 withdrawn from third column 109 may be used to remove intermediate boiling alcohols. Preferably, side stream 138 is taken from the middle or upper portion of third column 109 (above the feed location of the second residue). Most preferably, side stream 138 is withdrawn from above tray 25, for example from above tray 30 or from above tray 40. By adjusting the process parameters of third column 109 and withdrawing side stream 138 at an appropriate location, side stream 138 advantageously removes a significant portion of the intermediate boiling alcohol, e.g., n-propanol, from the feed in line 118. Side stream 138 preferably comprises from 0.01 wt.% to 10 wt.%, e.g., from 0.01 to 5 wt.% or from 0.01 wt.% to 3 wt.% n-propanol. By withdrawing side stream 138, a significant amount of n-propanol is removed to purify the ethanol in the third distillate in line 119. It is within the scope of the present invention to select the appropriate tray in the column from which to take a particular side stream based on column configuration and operating conditions. In addition, the contents of side stream 138 can comprise a denatured ethanol composition comprising ethanol and n-propanol. Thus, in this embodiment, the neat ethanol composition may be co-produced with the denatured ethanol composition. In other embodiments, each of the side stream 138 and the third distillate is, independently of the other, a denatured ethanol composition. For example, side stream 130 can comprise an n-propanol denatured ethanol composition, and third distillate 119 can comprise an ethyl acetate denatured ethanol composition. By performing the separation in this manner, the resulting third distillate 119 advantageously comprises less n-propanol. In other embodiments, at least a portion of the withdrawn side stream 138 can be combined with the third distillate 119 to form a denatured ethanol composition comprising at least a portion of the in situ-formed denaturant from the side stream 130.

Any compounds carried over from the feed or crude reaction product during distillation typically remain in the third distillate in an amount of less than 0.1 wt.%, e.g., less than 0.05 wt.% or less than 0.02 wt.%, based on the total weight of the third distillate composition. In one embodiment, one or more side streams can remove impurities from any of columns 107, 108, and/or 109 of system 100. In one embodiment, at least one side stream may be used to remove impurities from third column 109. The impurities may be purged and/or retained within the system 100.

The third distillate in line 119 can be further purified using one or more additional separation systems, such as a distillation column (e.g., a finishing column) or molecular sieves, to form an anhydrous ethanol product stream, i.e., "finished anhydrous ethanol.

Returning now to second column 108, the distillate in line 120 is preferably refluxed as shown in FIGS. 1A, 1B and 1C, for example at a reflux ratio of from 1: 10 to 10: 1, such as from 1: 5 to 5: 1 or from 1: 3 to 3: 1. As noted above, the second distillate comprises a significant portion of denaturants, such as ethyl acetate and/or acetaldehyde. Thus, all or a portion of the second distillate can be directed downstream as shown by line 120 and can be combined with, for example, ethanol that is further purified by third column 109. In addition, at least a portion of the distillate from second column 108 can be purged if necessary. In another embodiment, as shown in fig. 1B, a portion of the second distillate from second column 108 can be recycled to reaction zone 101 via line 120 to convert ethyl acetate to additional ethanol, e.g., can be recycled to reactor 103 and fed along with acetic acid feed line 105. In another embodiment, the second distillate in line 120 can be further purified to remove other components, such as acetaldehyde, using one or more additional columns (not shown). Such a configuration may be used in situations where the desired denaturant consists essentially of ethyl acetate, such as Part 21 of federal regulations (Part), formulation (formula) 35 or 35-a of title 27 (hereinafter abbreviated 27c.f.r.part 21) (incorporated herein by reference in its entirety). As another option, an additional column (not shown) may be used to remove ethyl acetate and leave acetaldehyde, which may be useful in cases where the desired denaturant contains acetaldehyde instead of ethyl acetate.

The system 100 in fig. 1C is similar to the system of fig. 1A and 1B, except that the second distillate in line 120 is also fed to a fourth column 123, also referred to as the "de-acetalization column". In fourth column 123, the second distillate is separated into a fourth distillate comprising acetaldehyde in line 124 and a fourth residue comprising ethyl acetate in line 125. The fourth distillate is preferably refluxed at a reflux ratio of from 1: 20 to 20: 1, such as from 1: 10 to 10: 1 or from 1: 5 to 5: 1, and at least a portion of the fourth distillate can be returned to reaction zone 101 via line 124 as shown. For example, the fourth distillate may be combined with the acetic acid feed, added to evaporator 110, or added directly to reactor 103. As shown, the fourth distillate is co-fed with acetic acid in line 105 to evaporator 110. Without being bound by theory, because acetaldehyde can be hydrogenated to form ethanol, recycling the acetaldehyde-containing stream to the reaction zone increases the yield of ethanol and reduces the production of byproducts and waste. In another embodiment (not shown in the figures), acetaldehyde may 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 derivatives. In a preferred embodiment, acetaldehyde is removed from the second distillate in the fourth column 123 such that no detectable amount of acetaldehyde is present in the residue of column 123.

In a preferred embodiment, at least a portion of the fourth distillate is combined (not shown) with the purified ethanol stream to form a denatured ethanol composition. Preferably, the denaturant comprises acetaldehyde and/or ethyl acetate. In other embodiments, at least a portion of the fourth distillate can be fed to third column 109. As a result, in these embodiments, the distillate exiting third column 109 can comprise at least a portion of the in situ formed acetaldehyde and/or ethyl acetate present in the fourth distillate. In these embodiments, the weight percent of acetaldehyde denaturant in the denatured ethanol composition may be as discussed previously. The weight ratio of the purified ethanol stream to the fourth distillate can vary widely and can be adjusted to achieve a particular desired concentration of denaturant in the denatured ethanol composition. For example, the weight ratio of the purified ethanol stream to the fourth distillate can be from 2: 1 to 75: 1, such as from 7: 1 to 50: 1.

The fourth residue comprises mainly ethyl acetate and ethanol. Preferably, at least a portion of the fourth residue is combined with the purified ethanol stream to form a denatured ethanol composition. Preferably, the denaturant comprises ethyl acetate. In other embodiments, at least a portion of the fourth residue can be fed to the third column 109. As a result, in these embodiments, the distillate exiting third column 109 can comprise at least a portion of the in situ formed ethyl acetate present in the fourth residue. In these embodiments, the weight percent of ethyl acetate denaturant in the denatured ethanol composition may be as discussed previously. The weight ratio of the purified ethanol stream to the fourth residue can vary widely and is adjusted to achieve a particular desired concentration of denaturant in the denatured ethanol composition. For example, the weight ratio of the purified ethanol stream to the fourth residue can be from 1: 1 to 50: 1, such as from 1.75: 1 to 20: 1. In other embodiments, the fourth residue of the fourth column 123 can be purged via line 125.

The fourth column 123 is preferably a tray column as described above and is preferably operated at above atmospheric pressure. In one embodiment, the pressure is from 120KPa to 5000KPa, for example, from 200KPa to 4,500KPa or 400 and 3000 KPa. In a preferred embodiment, the fourth column 123 can be operated at a higher pressure than the other columns.

The temperature of the fourth distillate exiting from fourth column 123 in line 124 is preferably from 60 ℃ to 110 ℃, e.g., from 70 ℃ to 100 ℃ or from 75 ℃ to 95 ℃. The temperature of the residue exiting the fourth column 125 is preferably from 70 ℃ to 115 ℃, e.g., from 80 ℃ to 110 ℃ or from 85 ℃ to 110 ℃. Exemplary components of the distillate and residue compositions of fourth column 123 are provided in table 6 below. It is understood that the distillate and residue may also contain other components not listed, such as components in the feed.

Fig. 1C also shows that the third residue in line 121 can be recycled to the second column 108. In one embodiment, recycling the third residue further reduces the aldehyde components in the second residue and concentrates these aldehyde components in the distillate stream 120 and thence to the fourth column 123, where the aldehydes can be more easily separated in the fourth column 123. These embodiments also provide a finished ethanol product preferably with low amounts of aldehydes and esters.

In several embodiments, the denaturant-containing stream and the purified ethanol stream are combined to form a denatured ethanol composition. In other embodiments, these denaturant-containing streams may be fed to third column 109 relative to being combined with the distillate of third column 109. In these cases, the denaturant fed to column 109 can be separated in the distillate of third column 109, and as such can be present in the purified ethanol. Thus, the third distillate may comprise a denatured ethanol composition.

As noted above, the denatured ethanol composition obtained by the process of the present invention comprises ethanol and at least one, such as at least two or at least three, denaturants. The denaturant may be generated in situ by a hydrogenation reaction, thus eliminating the need for an external source of denaturant. Preferably, the denaturant comprises ethyl acetate, acetaldehyde, diethyl ether, acetic acid, isopropanol and/or mixtures thereof.

The denaturant so produced should be present in an effective amount, e.g., an amount sufficient to provide a denatured ethanol composition in accordance with appropriate government regulations. As used herein, the term "denatured ethanol composition" refers to a composition comprising ethanol and one or more denaturants that are not suitable for use in beverages or in human pharmaceuticals for medical use, such as unpalatable. In other embodiments, the denatured ethanol may comprise "specially denatured ethanol," which is an ethanol composition denatured according to a formulation approved at 27c.f.r.part 21, Subpart D. Furthermore, the requirements for denatured ethanol vary for different applications, such as fuel applications and industrial applications. Thus, some applications may require higher amounts of denaturant while other applications may require lower amounts. Part 21 (incorporated herein by reference in its entirety) provides a listing of some of these applications. Table 7 shows some of the denaturing compositions in terms of the amount of denaturant added to 100 gallons of ethanol.

^*Ethanol is not less than 160 proof.

Further, in other embodiments, the denatured ethanol compositions of the present invention, as formed, correspond to denatured formulations in countries other than the united states. For example, in the uk, one formulation of commercial specific denatured alcohol is as follows. Not less than 20 parts by volume of ethyl acetate and 1 part by volume of isopropyl alcohol were mixed per 979 parts by volume of alcohol (whose concentration was not less than 85% by volume of alcohol).

Another exemplary british specific denatured alcohol formulation is as follows. Not less than 50 parts by volume of isopropyl alcohol is mixed per 950 parts by volume of alcohol (alcohol concentration not less than 85% by volume).

Of course, this list of U.S. and international denatured ethanol composition formulations is not exhaustive, and other formulations are certainly within the scope of the present invention.

Preferably, the denatured ethanol composition comprises 50 wt.% to 99 wt.%, e.g., 60 wt.% to 99 wt.% or 70 wt.% to 95 wt.% ethanol, and 0.01 wt.% to 40 wt.%, e.g., 0.01 wt.% to 25 wt.%, 0.01 wt.% to 20 wt.%, or 1 wt.% to 15 wt.% denaturant, based on the total weight of the denatured ethanol composition.

In addition to ethanol and denaturants, denatured ethanol compositions may also contain only trace amounts of other impurities such as acetic acid; c₃Alcohols such as n-propanol and isopropanol; and/or C₄-C₅An alcohol.

In some embodiments, as discussed above, the denatured ethanol composition of the present invention comprises at least a portion of the first column distillate. At this time, the denatured ethanol composition may contain ethyl acetate and/or acetaldehyde as a denaturant. Exemplary weight percent ranges for ethanol and denaturant (and other optional components) are provided in table 3 above. Preferably, the total amount of denaturants (ethyl acetate and acetaldehyde) in these denatured ethanol compositions is from 0.01 wt.% to 90 wt.%, e.g., from 0.01 wt.% to 65 wt.% or from 0.01 wt.% to 34 wt.% of denaturants.

In other embodiments, the denatured ethanol composition is withdrawn from a separation column in the separation zone. In these cases, the ethanol composition may, for example, comprise isopropanol denaturant in an amount of 0.1 wt.% to 10 wt.%, e.g., 1 wt.% to 9 wt.% or 3 wt.% to 7 wt.% isopropanol.

In other embodiments, the ethanol composition comprises diethyl ether, i.e., a denaturant, in an amount from 0.1 wt.% to 20 wt.%, e.g., from 0.1 wt.% to 10 wt.%, from 1 wt.% to 9 wt.%, or from 3 wt.% to 7 wt.% diethyl ether. In other embodiments, the ethanol composition comprises an acetic acid denaturant in an amount from 0.1 wt.% to 20 wt.%, e.g., from 1 wt.% to 15 wt.% or from 2 wt.% to 12 wt.% acetic acid. In other embodiments, the ethanol composition comprises the n-propanol denaturant in an amount from 0.001 to 10 wt.%, e.g., from 0.001 wt.% to 0.1 wt.%, from 0.1 wt.% to 10 wt.%, from 1 wt.% to 9 wt.%, or from 3 wt.% to 7 wt.% n-propanol.

In a preferred embodiment, the denatured ethanol composition is formed by combining a crude ethanol product-derived stream, e.g., a second distillate, comprising a denaturant with a purified ethanol stream. Exemplary weight percent ranges of ethanol with denaturants such as ethyl acetate and/or acetaldehyde (and other optional components) are provided in table 8. In some embodiments, the ethanol composition comprises an ethyl acetate denaturant in an amount from 0.01 wt.% to 40 wt.%, e.g., from 0.01 wt.% to 15 wt.%, from 0.01 wt.% to 10 wt.%, or from 0.01 wt.% to 9 wt.% ethyl acetate. In other embodiments, the ethanol composition comprises the acetaldehyde denaturant in an amount from 0.01 wt.% to 10 wt.%, e.g., from 0.01 wt.% to 5 wt.%, from 0.01 wt.% to 2 wt.%, or from 0.01 wt.% to 1 wt.% acetaldehyde. Preferably, the total amount of denaturants in these denatured ethanol compositions is 0.01 wt.% to 20 wt.%, e.g., 0.01 wt.% to 12 wt.% or 0.01 wt.% to 10 wt.% of denaturants.

In other embodiments, although the exemplary weight percent of water in the embodiments of table 8 is from 0.0001 wt.% to 1 wt.%, water may be present in the denatured ethanol composition in greater amounts. For example, the denatured ethanol composition may comprise water in an amount of 0.1 wt.% to 8 wt.%, e.g., 0.1 wt.% to 5 wt.%, or 0.1 wt.% to 2 wt.% water.

The denatured ethanol compositions produced by embodiments of the present invention may be suitable for use in a variety of applications, including fuels, solvents, chemical feedstocks, pharmaceutical products, detergents, sanitizers, or hydroconversion. In fuel applications, the denatured ethanol composition may be blended with gasoline for use in motor vehicles such as automobiles, boats, and small piston engine aircraft. In non-fuel applications, the denatured ethanol compositions may be used as solvents for cosmetic and cosmetic preparations, detergents, disinfectants, coatings, inks, and pharmaceuticals. The denatured alcohol composition may also be used as a processing solvent in manufacturing processes such as pharmaceutical products, food preparation, dyes, photochemical and latex processing.

The denatured ethanol composition may also be used as a chemical feedstock to make other chemicals such as vinegar, ethyl acrylate, ethyl acetate, ethylene, glycol ethers, ethylamines, aldehydes, and higher alcohols, particularly butanol. The denatured ethanol composition may be suitable for use as a feedstock in ester production. Preferably, in the preparation of ethyl acetate, the denatured ethanol composition may be esterified with acetic acid or reacted with polyvinyl acetate. The denatured ethanol composition may be dehydrated to produce ethylene. Ethanol may be dehydrated using any known dehydration catalyst, such as those described in U.S. publication nos. 2010/0030001 and 2010/0030002, the entire contents and disclosures of which are incorporated herein by reference. For example, zeolite catalysts may be used as dehydration catalysts. Preferably, the zeolite has a pore size of at least about 0.6nm, and preferred zeolites include dehydration catalysts selected from the group consisting of mordenite, ZSM-5, zeolite X and zeolite Y. For example, zeolite X is described in U.S. Pat. No.2,882,244 and zeolite Y is described in U.S. Pat. No.3,130,007, which are incorporated herein by reference in their entirety.

In order that the invention disclosed herein may be more effectively understood, the following non-limiting examples are provided. The following examples describe various embodiments of the ethanol compositions of the invention.

Examples

Example 1

A crude ethanol product comprising ethanol, acetic acid, water, and ethyl acetate was produced by reacting a gasification feed comprising 95.2 wt.% acetic acid and 4.6 wt.% water with hydrogen in the presence of a catalyst comprising 1.6 wt.% platinum and 1 wt.% tin supported on 1/8 inches of calcium silicate-modified silica extrudate at an average temperature of 291 ℃ and an outlet pressure of 2,063 KPa. Recycle of unreacted hydrogen back to the inlet of the reactor at 3,893hr^-1At a GHSV of 5.8, the total hydrogen/acetic acid molar ratio was determined. Under these conditions, 42.8% of the acetic acid was converted and the selectivity to ethanol was 87.1%, the selectivity to ethyl acetate was 8.4% and the selectivity to acetaldehyde was 3.5%. The crude ethanol mixture was purified using a separation scheme having a distillation column as shown in figure 1A.

The crude ethanol product was fed to the first column at a feed rate of 20 g/min. The composition of the liquid feed is provided in table 8. The first column was a 2 inch diameter Oldershaw with 50 trays. The column was operated at 115 ℃ at atmospheric pressure. Unless otherwise indicated, the column operating temperature is the temperature of the liquid in the reboiler and the pressure at the top of the column is atmospheric (about one atmosphere). The column pressure difference between the trays in the first column was 7.4 KPa. The first residue was withdrawn at a flow rate of 12.4g/min and returned to the hydrogenation reactor.

The first distillate was condensed and refluxed at the top of the first column in a 1: 1 ratio, and a part of the distillate was introduced into the second column at a feed rate of 7.6 g/min. The second column was a 2 inch diameter Oldershaw design equipped with 25 trays. The second column was operated at a temperature of 82 ℃ at atmospheric pressure. In this embodiment, no extractant is used. The column pressure difference between the trays in the second column was 2.6 KPa. The second residue was withdrawn at a flow rate of 5.8 g/min and directed to the third column. The second distillate was refluxed at a ratio of 4.5: 0.5 and the remaining distillate was collected for analysis. The compositions of the feed, distillate and residue are provided in table 9.

As shown in table 9, the first column distillate is a denatured ethanol composition, comprising ethanol and a significant portion of the in situ-forming denaturant.

The residue from the second column was collected from several runs and introduced into the third column, 2 inch Oldershaw containing 60 trays, at a rate of 10 g/min above the 25 th tray. The third column was operated at a temperature of 103 ℃ at atmospheric pressure. The column pressure difference between the trays in the third column was 6.2 KPa. The third residue was withdrawn at a flow rate of 2.7 g/min. The third distillate was condensed and refluxed at the top of the third column in a ratio of 3: 1. The composition of the recovered ethanol composition is shown in table 10. The ethanol composition comprises ethanol and a significant portion of the in situ formed ethyl acetate. Surprisingly and unexpectedly, the denatured ethanol composition is a denatured ethanol composition prepared without the addition of a denaturant. The ethanol composition also contained 10ppm of n-butyl acetate.

Example 2

Average temperature at 290 ℃ and outlet pressure of 2,049KPaNext, a caide ethanol product comprising ethanol, acetic acid, water, and ethyl acetate was produced by reacting a gasification feed comprising 96.3 wt.% acetic acid and 4.3 wt.% water with hydrogen in the presence of a catalyst comprising 1.6 wt.% platinum and 1 wt.% tin supported on 1/8 inches of calcium silicate-modified silica extrudate. Recycle of unreacted hydrogen back to the inlet of the reactor at 1,997hr^-1At a GHSV of 10.2. Under these conditions, 74.5% of the acetic acid was converted and the selectivity to ethanol was 87.9%, the selectivity to ethyl acetate was 9.5% and the selectivity to acetaldehyde was 1.8%. The crude ethanol mixture was purified using a separation scheme having a distillation column as shown in figure 1A.

The crude ethanol product was fed to the first column at a feed rate of 20 g/min. The composition of the liquid feed is provided in table 11. The first column was a 2 inch diameter Oldershaw with 50 trays. The column was operated at a temperature of 116 ℃ at atmospheric pressure. The column pressure difference between the trays in the first column was 8.1 KPa. The first residue was withdrawn at a flow rate of 10.7g/min and returned to the hydrogenation reactor.

The first distillate was condensed and refluxed at the top of the first column in a ratio of 1: 1, and a part of the distillate was introduced into the second column at a feed rate of 9.2 g/min. The second column was a 2 inch diameter Oldershaw design equipped with 25 trays. The second column was operated at a temperature of 82 ℃ at atmospheric pressure. The column pressure difference between the trays in the second column was 2.4 KPa. The second residue was withdrawn at a flow rate of 7.1 g/min and directed to the third column. The second distillate was refluxed at a ratio of 4.5: 0.5 and the remaining distillate was collected for analysis. The compositions of the feed, distillate and residue are provided in table 11.

As shown in table 11, the first column distillate is a denatured ethanol composition, comprising ethanol and a significant portion of the in situ-forming denaturant.

Example 3

A crude ethanol product comprising ethanol, isopropanol, acetic acid, water, and ethyl acetate was produced by reacting a gasification feed comprising 98 wt.% acetic acid and 2 wt.% acetone with hydrogen in the presence of a catalyst comprising 1.6 wt.% platinum and 1 wt.% tin supported on 1/8 inches of calcium silicate-modified silica extrudate at an average temperature of 291 ℃ and an outlet pressure of 1,420 KPa. The catalyst was diluted with 3mm glass beads in a 1: 1 volume ratio. Under these conditions, the acetone conversion was 68%, and after separation, the resulting ethanol/isopropanol mixture contained 4.3 wt.% isopropanol.

The composition of the resulting crude ethanol composition is provided in table 12.

As shown in table 12, the addition of acetone to the acetic acid feed provided an isopropanol product when the acetic acid feed was subjected to hydrogenation. A crude ethanol product formed from the hydrogenation provides a denatured ethanol composition comprising ethanol and 4.3 wt.% in situ-formed isopropanol.

In other embodiments, the denatured ethanol composition is formed by combining a crude ethanol product-derived stream comprising a denaturant with a purified ethanol stream. In this manner, denaturants from the derived stream are combined with the purified ethanol stream.

Example 4

The production of a caide ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by the hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme having a distillation column as shown in figure 1A. The second column operates as an extractive distillation column with an aqueous extractant.

The compositions of the distillate leaving the second column and the distillate leaving the third column are provided in table 13.

The second distillate and the third distillate of Table 13, when combined in weight ratios of 1.6: 1 and 21: 1, respectively, provide denatured ethanol compositions as shown in Table 14.

Example 5

The production of a caide ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by the hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme having a distillation column as shown in figure 1C.

The composition of the residue leaving the fourth column and the distillate leaving the third column are provided in table 15.

The third distillate and fourth residue of Table 15, when combined in weight ratios of 1.75: 1 and 20: 1, respectively, provide the denatured ethanol compositions as shown in Table 16.

Example 6

The production of a caide ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by the hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme having a distillation column as shown in figure 1C.

The compositions of the distillate leaving the fourth column and the distillate leaving the third column are provided in table 17.

The third distillate and the fourth distillate of Table 17, when combined in weight ratios of 7: 1 and 50: 1, respectively, provide denatured ethanol compositions as shown in Table 18.

Example 7

The production of a caide ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by the hydrogenation of acetic acid is discussed above. The crude ethanol product was purified using a separation scheme having a distillation column as shown in figure 1A.

The compositions of the distillate leaving the first column and the distillate leaving the third column are provided in table 19.

The third distillate and the first distillate of Table 19, when combined in weight ratios of 0.05: 1 and 3: 1, respectively, provide denatured ethanol compositions as shown in Table 20.

Example 8

The production of a caide ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by the hydrogenation of acetic acid is discussed above. The crude ethanol product can be purified using a first column. However, in this separation scheme, the first distillate can be sent directly to the third column, thus bypassing the second and/or fourth columns. The third column can provide a residue and a distillate. The compositions of the first distillate and the third distillate are provided in table 24. The third distillate is a denatured ethanol composition that may be advantageously produced without the need for a second or fourth column.

Example 9

The production of a caide ethanol product comprising ethanol, acetic acid, acetaldehyde, water, and ethyl acetate by the hydrogenation of acetic acid is discussed above. The crude ethanol product is purified using a separation scheme as shown in fig. 1A, particularly having first and second distillation columns.

The residue from the second column was collected from several runs and introduced at a rate of 18 g/min into a third column, 2 inch Oldershaw containing 50 trays. The third column was operated at a temperature of 102 ℃ at atmospheric pressure. The column pressure difference between the trays in the third column was 6.2 KPa. The third residue was taken off at a flow rate of 13 g/min. The third distillate was condensed and refluxed at the top of the third column in a ratio of 3: 2.

The composition of some of the components in the second residue stream at multiple tray locations within the third column is shown in fig. 2. Ethanol is also present in significant amounts at each tray.

As shown in fig. 2, a side stream may be withdrawn from the third column. Preferably, the withdrawn side stream comprises ethanol and n-propanol. A side stream withdrawn from the third column provides a denatured ethanol composition comprising ethanol and n-propanol. In some embodiments, a side stream can be combined with a purified ethanol stream, such as a third distillate, to form a separate denatured ethanol composition. Surprisingly and unexpectedly, each of these denatured ethanol compositions can be prepared without the addition of external denaturants.

In the example of FIG. 2, the side stream can be in the range of trays 22 to 52, for example tray 25 to tray 43; tray 25-tray 40; or from tray 26 to tray 39. However, the sample of FIG. 2 is merely exemplary. It is within the scope of the invention to adjust the side stream take off location based on process parameters to achieve the desired side stream composition.

Although the present invention has been described in detail, various modifications within the spirit and scope of the invention will be apparent to those skilled in the art. In view of the above discussion, relevant knowledge in the art and references discussed above in relation to the background and detailed description, the disclosures of which are incorporated herein by reference in their entirety. Furthermore, it is to be understood that various aspects of the invention as well as various portions of various embodiments and features recited below and/or in the appended claims may be combined or interchanged either in part or in whole. In the foregoing description of the various embodiments, the embodiments that refer to another embodiment may be combined with other embodiments as appropriate, as will be recognized by those skilled in the art. Furthermore, those skilled in the art will recognize that the foregoing description is by way of example only, and is not intended to limit the present invention.

Claims (46)

1. A method of producing a denatured ethanol composition, the method comprising:

hydrogenating acetic acid in the presence of a catalyst to form a caide ethanol product comprising ethanol and at least one denaturant;

separating the caide ethanol product in one or more separation units into a denatured ethanol composition and one or more derivative streams, wherein the denatured ethanol composition comprises from 0.01 wt.% to 40 wt.% of a denaturant, based on the total weight of the denatured ethanol composition.

2. The method of claim 1, wherein the at least one denaturant is selected from the group consisting of acetaldehyde, butyraldehyde, diethyl ether, and methanol.

3. The processes 1 and 2 of any one of claims, wherein the at least one denaturant comprises ethyl acetate.

4. The method of any one of claims 1-3, wherein the at least one denaturant comprises acetaldehyde.

5. The method of any one of claims 1-3, wherein the at least one denaturant comprises isopropanol.

6. The method of any one of claims 1-3, wherein the at least one denaturant comprises diethyl ether.

7. The method of any one of claims 1-3, wherein the at least one denaturant comprises acetic acid.

8. The process of any of claims 1-3, wherein the denatured ethanol composition comprises from 50 wt.% to 99 wt.% ethanol.

9. The process of any of claims 1-8, wherein the acetic acid feed comprises acetic acid and propionic acid.

10. The process of claim 9, wherein the propionic acid is hydrogenated to produce n-propanol.

11. The method of claim 10, further comprising:

separating at least a portion of the caide ethanol product in a first column into a first distillate comprising ethanol and n-propanol, and a first residue comprising acetic acid;

separating at least a portion of the first distillate in a second column into a second distillate and a second residue comprising ethanol, at least a portion of n-propanol, and water; and

separating at least a portion of the second residue in a third column into a third distillate comprising ethanol and a third residue comprising water.

12. The method of claim 11, further comprising:

a side stream comprising n-propanol is withdrawn from the third column.

13. The process of any of claims 1-12, wherein the caide ethanol product further comprises:

based on the total weight of the crude ethanol product,

0.01 wt.% to 20 wt.% ethyl acetate;

0.01 wt.% to 10 wt.% acetaldehyde;

0.01 wt.% to 10 wt.% isopropyl alcohol;

0.01 wt.% to 20 wt.% diethyl ether;

0 wt.% to 90 wt.% acetic acid; and

5 wt.% to 35 wt.% water.

14. The process of any of claims 1-13, wherein the acetic acid feed comprises acetic acid and acetone, and the at least one denaturant comprises isopropanol.

15. The process of any of claims 1-14, further comprising contacting acetic acid with hydrogen in a co-reactor under conditions effective to form acetone.

16. The process of any one of claims 1-14, wherein the denatured ethanol composition, as formed, comprises from 0.1 wt.% to 10 wt.% isopropanol, based on the total weight of the denatured ethanol composition.

17. The method of any one of claims 1-16, wherein the separating comprises:

separating a first portion of the caide ethanol product into an ethanol stream and one or more derivative streams;

purifying the ethanol stream to form a purified ethanol stream; and

combining a second portion of the crude ethanol product with the purified ethanol stream to form a denatured ethanol composition.

18. The method of any one of claims 1-17, wherein the isolating comprises:

separating at least a portion of the caide ethanol product into an ethanol stream and one or more derivative streams;

purifying the ethanol stream to form a purified ethanol stream; and

combining at least a portion of the acetic acid feed with the purified ethanol stream to form a denatured ethanol composition.

19. The method of any one of claims 1-18, further comprising:

at least a portion of the caide ethanol product is separated in a first column into a first distillate comprising ethanol, acetaldehyde, and ethyl acetate, and a first residue comprising acetic acid.

20. The method of any one of claims 1-19, further comprising:

separating at least a portion of the first distillate into an ethanol stream and a denaturant stream comprising acetaldehyde and ethyl acetate;

purifying the ethanol stream to form a purified ethanol stream; and

combining at least a portion of the denaturant stream with the purified ethanol stream to form a denatured ethanol composition.

21. The method of any one of claims 1-19, further comprising:

separating at least a portion of the first distillate into an ethanol stream;

purifying the ethanol stream to form a purified ethanol stream; and

combining at least a portion of the first residue with the purified ethanol stream to form a denatured ethanol composition.

22. The method of any one of claims 1-19, further comprising:

separating at least a portion of the first distillate in a second column into a second distillate comprising ethyl acetate and/or acetaldehyde, and an ethanol stream;

purifying the ethanol stream to form a purified ethanol stream; and

combining at least a portion of the second distillate with the purified ethanol stream to form a denatured ethanol composition.

23. The process of claim 22, wherein the second column is an extractive distillation column.

24. The method of any one of claims 1-19, further comprising:

separating at least a portion of the first distillate in a second column into a second residue comprising ethyl acetate, and an ethanol stream;

purifying the ethanol stream to form a purified ethanol stream; and

combining at least a portion of the second residue with the purified ethanol stream to form a denatured ethanol composition.

25. The process of claim 24, wherein the second column is a non-extractive distillation column.

26. The method of any one of claims 1-19, further comprising:

separating at least a portion of the first distillate in a second column into a second residue comprising ethyl acetate, and an ethanol stream;

separating at least a portion of the second residue in a third column into a third distillate comprising ethyl acetate and ethanol.

27. The method of any one of claims 1-26, wherein the denaturant comprises ethyl acetate, and wherein the denatured ethanol composition further comprises:

based on the total weight of the crude ethanol product,

0.01 wt.% to 40 wt.% ethyl acetate;

50 wt.% to 99 wt.% ethanol; and

1 wt.% to 35 wt.% water.

28. The method of any one of claims 1-26, wherein the denaturant comprises acetaldehyde, and wherein the denatured ethanol composition further comprises:

based on the total weight of the crude ethanol product,

0.01 wt.% to 10 wt.% acetaldehyde;

50 wt.% to 99 wt.% ethanol; and

1 wt.% to 35 wt.% water.

29. The method of any one of claims 1-26, wherein the denaturant comprises isopropanol, and wherein the denatured ethanol composition further comprises:

based on the total weight of the crude ethanol product,

0.1 wt.% to 10 wt.% isopropyl alcohol;

50 wt.% to 99 wt.% ethanol; and

1 wt.% to 35 wt.% water.

30. The process of any one of claims 1-26, wherein the denaturant comprises diethyl ether, and wherein the denatured ethanol composition further comprises:

based on the total weight of the crude ethanol product,

0.1 wt.% to 20 wt.% diethyl ether;

50 wt.% to 99 wt.% ethanol; and

1 wt.% to 35 wt.% water.

31. The method of any one of claims 1-26, wherein the denaturant comprises acetic acid, and wherein the denatured ethanol composition further comprises:

based on the total weight of the crude ethanol product,

0.01 wt.% to 20 wt.% acetic acid

50 wt.% to 99 wt.% ethanol; and

1 wt.% to 35 wt.% water.

32. The method of any one of claims 1-26, wherein the denaturant comprises n-propanol, and wherein the denatured ethanol composition further comprises:

based on the total weight of the crude ethanol product,

0.1 wt.% to 10 wt.% n-propanol

50 wt.% to 99 wt.% ethanol; and

1 wt.% to 35 wt.% water.

33. A denatured ethanol composition formed by the method of any one of claims 1-32.

34. A fuel composition comprising the denatured ethanol composition of claim 33.

35. A feedstock for ester production comprising the denatured ethanol composition of claim 33.

36. A solvent comprising the denatured ethanol composition of claim 33.

37. A method of producing a denatured ethanol composition, the method comprising:

hydrogenating an acetic acid feed in the presence of a catalyst to form a caide ethanol product comprising ethanol and a denaturant;

separating the caide ethanol product into an ethanol stream and at least one derivative stream comprising a denaturant;

further purifying the ethanol stream to form a purified ethanol stream; and

combining at least a portion of the at least one derivative stream with the purified ethanol stream to produce a denatured ethanol composition.

38. The process of claim 37, wherein the denatured ethanol composition comprises 50-99 wt.% ethanol and 0.01-40 wt.% denaturant.

39. The process of claim 37, wherein the caide ethanol product comprises:

based on the total weight of the crude ethanol product,

5 wt.% to 70 wt.% ethanol;

0.01 wt.% to 10 wt.% acetaldehyde;

0.01 wt.% to 10 wt.% isopropyl alcohol;

0.01 wt.% to 20 wt.% diethyl ether;

0.01 wt.% to 20 wt.% ethyl acetate;

0 wt.% to 90 wt.% acetic acid; and

5 wt.% to 35 wt.% water.

40. The method of any one of claims 37-39, wherein the denaturant is selected from the group consisting of acetaldehyde, butyraldehyde, diethyl ether, and methanol.

41. The method of any one of claims 37-40, wherein the denaturant is ethyl acetate.

42. The method of any one of claims 37-41, further comprising:

separating at least a portion of the caide ethanol product in a first column into a first distillate comprising ethanol and a denaturant, and a first residue comprising acetic acid;

separating at least a portion of the first distillate in a second column into a second distillate comprising a denaturant and a second residue comprising an ethanol stream; and

separating at least a portion of the ethanol stream in a third column into a third distillate comprising a purified ethanol stream and a third residue comprising water.

43. The process of claim 42, further comprising adding at least a portion of the second distillate to at least a portion of the purified ethanol stream to produce a denatured ethanol composition.

44. A method of producing a denatured ethanol composition, the method comprising:

hydrogenating an acetic acid feed comprising acetic acid and acetone in the presence of a catalyst to form a crude ethanol product comprising ethanol and isopropanol;

separating the caide ethanol product in one or more separation units into a denatured ethanol composition and one or more derivative streams, wherein the denatured ethanol composition, as formed, comprises ethanol and from 0.1 wt.% to 10 wt.% isopropanol, based on the total weight of the denatured ethanol composition.

45. The process of claim 44, wherein the caide ethanol product comprises:

based on the total weight of the crude ethanol product,

5 wt.% to 70 wt.% ethanol;

0.01 wt.% to 10 wt.% acetaldehyde;

0.01 wt.% to 10 wt.% isopropyl alcohol;

0 wt.% to 20 wt.% ethyl acetate; and

5 wt.% to 35 wt.% water.

46. A denatured ethanol composition formed by the method of any one of claims 37-45.