MXPA98010028A - Improved procedure for the hydrogenation of maleic acid to 1,4-butanod - Google Patents

Abstract

The present invention relates to: Hydrogenated maleic acid and / or other hydrogenatable precursors in the presence of a noble metal catalyst to 1,4-butanediol. Production and yields of 1,4-butanediol are increased by the addition of iron to the hydrogenab precursor feed

Description

IMPROVED PROCEDURE FOR THE HYDROGENATION OF MALEIC ACID TO 1,4-BUTANODIOL BACKGROUND OF THE INVENTION Field of the Invention This invention relates to an improved process for the hydrogenation of maleic acid, maleic anhydride or other hydrogenatable precursor to 1,4-butanediol and tetrahydrofuran. The improvement consists in the addition of iron to maleic acid, maleic anhydride or other hydrogenatable precursor feed material. The addition of iron in the feed material improves the performance of the catalyst to reaction products with higher yields of 1,4-butanediol and minimal formation of by-products. DESCRIPTION OF THE PRIOR ART It is well known that tetrahydrofuran, gamma-butyrolactone and 1,4-butanediol are obtained by catalytic hydrogenation of maleic anhydride and related compounds. Tetrahydrofuran is a useful solvent for natural and synthetic resins and is a valuable intermediary in the manufacture of a series of chemicals and plastics. Gamma-butyrolactone is an intermediate for the synthesis of compounds of butyric acid, polyvinylpyrrolidone and methionine. Gamma-butyrolactone is a useful solvent for acrylate and styrene polymers and also a useful component of paint removers and textile aids. 1,4-Butanediol (also known as 1,4-butylene glycol) is useful as a solvent, humectant, intermediate for plasticizers and pharmaceuticals, a crosslinking agent for polyurethane elastomers and a precursor in the manufacture of tetrahydrofuran and is used to prepare plastics from terephthalate Numerous catalysts and processes have been described for the hydrogenation of maleic acid, maleic anhydride or other hydrogenatable precursor to tetrahydrofuran, gamma-butyrolactone and 1,4-butanediol. The processes catalyzed by a supported noble metal catalyst are of specific interest in the present invention. It has been taught in the art that said catalysts may also contain iron. For example / US Pat. 4,985,572 shows a process for the catalytic hydrogenation of a carboxylic acid or an anhydride thereof to the corresponding alcohol and / or carboxylic acid ester using a catalyst consisting of rhenium, palladium and at least one other metal capable of alloying with palladium, all on a carbon support. The preferred metal capable of alloying with the palladium is silver, but gold, copper, nickel, rhodium, tin, cobalt, aluminum, manganese, gallium, iron, chromium and platinum are also described. The preparation of this catalyst is characterized by the simultaneous deposition of palladium and silver on the carbon support, followed by a thermal treatment at a high temperature (600 ° C). The rhenium is then deposited on the carbon support impregnated with palladium / alloy metal. The resulting catalyst is then reduced. Additionally, WO 92/02298 describes a hydrogenation catalyst consisting of palladium and rhenium and one or more metals selected from the group consisting of rhodium, cobalt, platinum, ruthenium, iron, thulium, cerium, yttrium, rxeodinium, aluminum, praseodinium. , holmium, hafnium, manganese, vanadium, chromium, gold, terbium, lutetium, nickel, scandium and niobium, on a support. In general, in the hydrogenation of maleic acid, maleic anhydride or other hydrogenatable precursor, the catalysts discussed above are prone to produce more tetrahydrofuran and gamma-butyrolactone than 1,4-butanediol. An object of this invention is a process that makes the production of 1,4-butanediol is maximal and that the production of gamma-butyrolactone is minimal. SUMMARY OF THE INVENTION The present invention is a process for the production of 1,4-butanediol, consisting of the catalytic hydrogenation of a feed material consisting of a hydrogenatable precursor and iron in contact with a hydrogen-containing gas. DETAILED DESCRIPTION OF THE INVENTION Maleic acid or another hydrogenatable precursor is hydrogenated in the presence of a noble metal catalyst at 1, 4 -butanediol. The production and yields of 1,4-butanediol are increased by the addition of iron or an iron-containing compound to the feed. Reagents In the process of the present invention, at least one hydrogenatable precursor reacts with a hydrogen-containing gas in the presence of the catalyst. As used herein, a "hydrogenatable precursor" is any carboxylic acid or anhydride thereof, carboxylic acid ester, lactone or mixture thereof which, when hydrogenated, produces 1,4-butanediol. Representative hydrogenatable precursors include maleic acid, maleic anhydride, fumaric acid, succinic anhydride, succinic acid, succinate esters such as dialkyl succinates Cx to Ca (eg dimethyl succinate), maleate esters such as dialkyl maleates C a C8 (for example, dimethyl maleate), gamma-butyrolactone or mixtures thereof. Preferred hydrogenatable precursors are maleic acid, maleic anhydride, succinic acid, succinic anhydride, fumaric acid, esters of C4 acids, gamma-butyrolactone or mixtures thereof. The most preferred hydrogenatable precursor is maleic acid, which is typically obtained by reacting n-butane or benzene in an oxygen-containing gas in the presence of a catalyst to oxidize in the vapor phase n-butane or benzene to maleic anhydride and collecting then the maleic anhydride cooling with water to produce maleic acid in an aqueous solution. The oxidation of n-butane or benzene is typically operated at a temperature of about 300 ° C to 600 ° C and a pressure of about 0.5 to 20 atmospheres (50 to 2,000 kPa). Typically, the hydrogen-containing gas (H2) is commercially pure hydrogen without diluent gases. However, the hydrogen-containing gas, in addition to hydrogen (H2), may also contain nitrogen (N2), any gaseous hydrocarbon (eg, methane), as well as gaseous carbon oxides (eg, carbon monoxide, carbon dioxide). carbon). Catalyst The catalyst used in the present invention consists of a noble metal of Group VIII of the Periodic Table, selected from the group consisting of at least one of palladium, ruthenium, rhodium, osmium, iridium and platinum. These include (i) catalysts which also contain at least one of rhenium, manganese or tellurium, as described in UK Patent Publication No. 01551741; (ii) catalysts also containing at least one of silver and gold, as described in US Pat. 4,096,156, and (iii) catalysts also containing at least one metal capable of alloying with the noble metal of Group VIII and at least one of rhenium, tungsten or molybdenum, as described in Patent 5,149,680. Examples of another suitable catalyst include palladium and rhenium on a carbon support, as described in UK Patent Publication No. 01543232 and in US Pat. 4,659,686. This catalytic composition can also be further modified through the incorporation of a metal or metals selected from Groups IA, IIA or VIII. The preferred catalyst employed in the present invention consists of palladium, silver and rhenium supported on carbon. The carbons for use in this invention have a BET surface area of at least 200 m2 / g and, preferably, are in the range of 500-1,500 m2 / g. Catalysts of this type are described in US Pat. 5,149,680.

The preferred catalyst composition consists of about 0.1 to about 20 weight percent palladium, preferably about 2 to about 8 weight percent palladium; about 0.1 to about 20 weight percent silver, preferably about 1 to about 8 weight percent silver; about 0.1 to about 20 weight percent rhenium, and preferably about 1 to about 10 weight percent rhenium. The ratio of palladium to silver is between 10 to 1 and 1 to 10. As previously suggested, this catalyst composition can also be further modified through the incorporation of a metal or metals selected from Groups IA or IIA. Preferred catalysts for use in this invention can be conveniently prepared by impregnation of the carbon support, either in single or multiple stages of impregnation, with a solution or solutions containing at least one palladium, silver or rhenium compound. As used herein, impregnation of the carbon support means causing the carbon support to be filled, soaked, permeated, saturated or coated. The impregnating solution may optionally contain complexing agents to aid the solubilization of one or more of the metal compounds. The catalyst is dried after each impregnation step to remove any vehicle solvent. The drying temperatures are between about 80 ° C and about 150 ° C. In preparing the preferred catalysts, the solutions of palladium compound, silver compound and rhenium compound can be applied to the carbon by immersion or suspension of the support material in the solution or by spraying the solution onto the carbon. The solution containing the palladium compound is typically an aqueous solution containing an amount of palladium compound which gives a catalytic product with the required amount of palladium. The palladium compound can be palladium nitrate or a palladium compound such as a chloride, carbonate, carboxylate, acetate, acetylacetonate or amine. The solution containing the silver compound is typically an aqueous solution containing an amount of silver compound that gives a catalytic product with the required amount of silver. The palladium and silver compounds must be thermally decomposable and reducible to metals. The solution containing the rhenium compound is typically an aqueous solution containing an amount of rhenium compound which gives a catalytic product with the required amount of rhenium. The rhenium compound is typically perrhenium acid, ammonium perrhenate or an alkali metal perrhenate. The impregnating solution (s) may (optionally) contain metal complexing agents to help solubilize one or more of the metal compounds. The addition of acetonitrile to the impregnating solution makes it possible to add the compounds of Pd, Ag and Re in a single step. Nitric acid can also be added to the impregnating solution. After impregnation with palladium, silver and rhenium and drying, the preferred catalyst is activated by heating the impregnated carbon support under reducing conditions at a temperature of 120-350 ° C, preferably 150-300 ° C. Hydrogen, or a mixture of hydrogen and nitrogen, can be conveniently used in contact with the catalyst for the reduction of the catalyst. The reduction of the impregnated carbon support is only after having impregnated the carbon support with palladium, silver and rhenium. In the case of multiple stages of impregnation and multiple drying, the reduction of the catalyst is carried out after the final drying. The method The method for carrying out the process consists in the reaction of a hydrogenatable precursor with a gas containing hydrogen in the presence of iron and the hydrogenation catalyst and in the recovery and purification of the reaction products by distillation. In the present invention, the iron is added to the hydrogenatable precursor prior to the introduction of the hydrogenatable precursor into the hydrogenation reactor or in situ. Typically, iron is added as an iron salt. The iron is preferably added to the liquid hydrogenatable precursor feedstock in concentrons ranging from 1 to 10,000 ppm (on a weight-to-weight basis). Preferably, the concentration of iron in the feedstock is between about 20 and 160 ppm. A wide range of iron salts can be used, including iron acetate, iron propionate, iron butyrate, iron maleate, iron succinate, and iron fumarate. Preferably, the anion of the salt should not interfere with the hydrogenation reaction or act to eat poison for the hydrogenation catalyst. The liquid phase hydrogenation of this invention can be carried out using conventional apparatus and techniques in a stirred tank reactor or a fixed bed reactor. Single or multi-stage reactors can be used. The amount of catalyst required will vary widely and depends on a number of factors, such as reactor size and design, contact time and the like. The gas containing hydrogen is fed continuously, generally with hydrogen, in a considerable stoichiometric excess with respect to the other reagents. Unreacted hydrogen can be returned to the reactor as recycle stream. The solution of the precursor, for example solution of maleic acid (or other hydrogenatable precursor), is fed continuously at concentrations ranging from diluted solutions to almost the maximum level of solubility. The precursor solution may contain about 10 to about 60 weight percent maleic acid (or other hydrogenatable precursor), higher concentrations being more economical and preferred, because there is less water to be recycled or disposed of. Preferably, the precursor solution contains about 20 to about 50 weight percent maleic acid (or other hydrogenatable precursor). Preferably the hydrogenation step is carried out at a temperature of about 50 ° C to 350 ° C and at a hydrogen pressure of about 20-400 atmospheres, with hydrogen to hydrogenatable precursor (H2 / P) ratios of between 5 to 1. and 1,000 to 1 and contact times of 0.1 minute to 20 hours.

The reaction products, 1,4-butanediol, tetrahydrofuran, gamma-butyrolactone or their mixtures are advantageously separated by fractional distillation. The byproducts formed in small quantities or the unreacted feed, such as, for example, succinic anhydride or succinic acid, are eventually returned to the hydrogenation step. The gamma-butyrolactone can also be recycled to the hydrogenation reactor. Using the process of this invention, more specifically using the hydrogenation catalyst described herein, the maleic acid is converted virtually quantitatively into a simple reaction. The 1,4-butanediol and tetrahydrofuran yields obtained are about 80 mole percent or more, typically about 90 mole percent or greater, with a major portion of the product being 1,4-butanediol.

The reaction of the by-products can include n-butanol, n-butyric acid, n-propanol, propionic acid, methane, propane, n-butane, carbon monoxide and carbon dioxide. However, the formation of unusable byproducts is slight. SPECIFIC EMBODIMENTS In order to illustrate the present invention, the following examples are given.

Example 1: Preparation of a Pd + Ag + Re catalyst on carbon 132.4 g of palladium nitrate solution (8.5 wt% of Pd), 17.3 g of silver nitrate, 28 g of concentrated nitric acid (70% by weight) and acetonitrile (about 40 cc) in a 250-c volumetric flask. The mixture was stirred to dissolve the silver nitrate and 45 g of perrhenic acid (53.3% by weight) were then slowly added.

Re) Acetonitrile was then added to the flask to give exactly 250 cc of solution. 280.5 g of CECA carbon extruded ACL40 of 1.5 mm (diameter) were impregnated gradually with the above solution. The mixture was allowed to stand for 4 hours and then dried in an oven at 120-130 ° C for 20.25 hours. To study the catalyst, the extrudate was cut with a razor blade, such that the maximum length of the extrudate was about 1.5 mm. Example 2: Hydrogenation of aqueous maleic acid and study of the catalyst The catalyst of Example 1 was studied in two Hasteloy C276 reactors connected in series, using hot Hasteloy C276 pipes. The reactors had an internal diameter of 0.516"and each was equipped with an axial Hasteloy C276 1/8" thermocouple. The catalyst was mixed with 50/70 mesh quartz chips (0.625 g of quartz per g of catalyst) before loading into the reactor. 20 cc (12.15 g) of catalyst were placed in the first reactor and 40 cc (24.3 g) in the second reactor. Before the study, the catalyst was reduced to atmospheric pressure in flowing hydrogen (400 emee), heating the catalyst gradually to 230 ° C for about 13 to 18 hours and then maintaining the catalyst at 230 ° C for about 5 hours. An extensive catalyst study was carried out over several thousand hours at pressures of 2,500 to 4,000 psig. The reactors were operated with hydrogen recycling. A small portion of the hydrogen was evacuated to prevent the accumulation of non-condensable gases. The aqueous maleic acid feed that was used for the iron addition study contained small amounts of other organic acids, as summarized in Table 1. Iron was added to maleic acid in the form of iron (II) acetate to obtain a solution containing 40 ppm (w / w) iron. The iron dissolved easily in the solution. The effect of the addition of iron to the maleic acid feed was evaluated between 4450 and 4550 hours in current, with the following procedure conditions: Pressure: 4,000 psig. Feed ratio H2 / (MAC + FAC): 92. Composition ratio to H2 recycling: 0.083.

First reactor: Fixed average temperature: 130 ° C. Second reactor: Fixed average temperature: 162 ° C. Table 2 summarizes the results of the study with and without the addition of iron to the maleic acid feed. The selectivities of the product were calculated on a C4 molar basis. The yield of BDO was significantly higher for the iron added to the maleic acid feed. Table 1 - Composition of maleic acid feed Component% Weight Maleic acid 33,4 . Fumaric acid 0.41 Acrylic acid 0.21 Acetic acid 0.72 Malic acid 0.40 Table 2 - Catalyst performance data (selectivity)% BDO% THF% GBL% BuOH% PrOH% ACS Adding iron 69.2 19, 75 5.38 2.86 0.63 2.04 Without adding iron 61.7 28.02 4.63 3.11 0.63 1.74 where: BDO = 1,4-butanediol THF = tetrahydrofuran GBL = gamma- butyrolactone BuOH = butanol PrOH = propanol ACS = succinic acid It is to be understood that the invention in question is not limited by the examples set forth herein. These have been provided merely to demonstrate the operability and selection of the catalysts, the metal sources, the carbon supports, the concentrations, the contact times, the solids charges, the feedstocks, the reaction conditions and the Products, if any, can be determined by the total provided memory, without departing from the spirit of the invention herein developed and described, the scope of the invention including modifications and variations falling within the scope of the appended claims.

Claims (12)

1. CLAIMS 1. A process for the production of 1,4-butanediol, consisting of the catalytic hydrogenation of a hydrogenatable precursor in contact with a hydrogen-containing gas and a hydrogenation catalyst consisting of at least one noble metal of Group VIII of the Table Periodic, where iron is added to the hydrogenatable precursor.
2. 2. The process of claim 1, wherein "the hydrogenatable precursor is selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, succinic acid, succinic anhydride, C to C8 dialkyl succinates, dialkyl maleates C to Cs, gamma-butyrolactone and its mixtures 3.
3. The process of claim 2, wherein the hydrogenatable precursor is at least one of maleic acid, succinic acid or gamma-butyrolactone 4.
4. The process of claim 1, wherein the noble metal of the group VIII is selected from the group consisting of palladium, platinum, rhodium and ruthenium 5.
5. The process of claim 1, wherein the hydrogenation catalyst consists of palladium and rhenium 6.
6. The process of claim 1, wherein the hydrogenation catalyst consists of palladium, rhenium and "silver on a carbon support.
7. The process of claim 1, wherein the iron is an iron salt selected from the group of iron acetate, iron propionate, iron butyrate, iron maleate, iron succinate, iron fumarate and mixtures thereof.
8. The process of claim 1, wherein the iron is added to the hydrogenatable precursor at concentrations ranging from 1 to 10,000 ppm (weight-to-weight basis).
9. The process of claim 1, wherein the iron is added to the liquid hydrogenatable precursor at concentrations ranging from about 20 to about 160 ppm (weight-to-weight basis).
10. The process of claim 1, wherein the ratio of hydrogen to hydrogenatable precursor is between about 5 to 1 and about 1,000 to 1.
11. The process of claim 1, wherein the hydrogen-containing gas pressure is between approximately 20 and 400 atmospheres.
12. 12. The method of claim 1, wherein the contact time is between about 0.1 minute and 20 hours.