PROCESS FOR PREPARING BUTYROLACTONES AND BUTANEDIOLS

Abstract: A process is disclosed for preparing butyrolactones, butanediols, and mixtures thereof comprising hydrogenating a hydrogenatable precursor in the presence of an aqueous reaction medium and a catalyst comprising palladium or combinations thereof with rhenium and at least one support selected from the oxides of titanium, zirconium, and hafnium.

Description: BACKGROUND OF THE INVENTION Field of the Invention The invention concerns making butyrolactones, butanediols, and mixtures thereof by hydrogenating a variety of hydrogenatable precursors such as maleic acid, fumaric acid, succinic acid, itaconic acid, or mixtures thereof. Background of the Invention Butyrolactone is a known compound which is employed in the synthesis of pyrrolidone, glutaric acid, and many other compounds. Improved processes for preparing butyrolactone are of interest to the chemical industry. The following references disclose known processes for making butyrolactone. U.S. Patent 4,096,156 discloses a process for the preparation of gamma-butyrolactone by catalytic hydrogenation of maleic acid, maleic acid anhydride, succinic acid, succinic acid anhydride, or fumaric acid, or of a mixture of two or more of these compounds. The catalyst contains a mixture of an element of the VIII th subgroup of the periodic system of elements or of one of its compounds with an element of group IB of the periodic system of elements or of one of its compounds. U.S. 4,105,674 discloses a process for producing gamma-butyrolactone by hydrogenating a feed compound selected from the group consisting of maleic acid, succinic acid, maleic anhydride, succinic anhydride, and mixtures of any of the foregoing in the vapor phase. The reaction is conducted in the presence of a Cu-Pd or Cu-Pt catalyst. U.S. 3,113,138 discloses a process for preparing butyrolactone which comprises hydrogenating succinic anhydride in the liquid phase in the presence of a solvent selected from the group consisting of lower alkyl acetates and dioxane, and a catalyst comprising palladium deposited on a carrier selected from the group consisting of activated carbon and activated alumina, at a pressure of at least 200 p.s.i.g., while maintaining the temperature in the range of 30-95°C, until at least a major portion of the reaction has taken place. EP-A-147,219 describes a process for preparing tetrahydrofuran, 1,4-butanediol or mixtures thereof comprising hydrogenating a hydrogenatable precursor in the presence of a solvent medium and a catalyst, the catalyst being a composite of palladium and rhenium on a carbon support, the composite comprising about 0.5% to 10% of palladium and about 1% to 10% of rhenium by total weight, the palladium being present in the form of crystallites having an average size of about 10 nm to 25 nm and the rhenium being present in the form of a highly dispersed phase of crystallites having an average size of less than about 2.5 nm. SUMMARY OF THE INVENTION The present invention provides a process for preparing butyrolactones, butanediols, and mixtures thereof comprising hydrogenating a hydrogenatable precursor in the presence of an aqueous reaction medium and a catalyst comprising palladium or combinations thereof with rhenium and at least one support selected from the oxides of titanium, zirconium, and hafnium. DETAILED DESCRIPTION OF THE INVENTION The invention provides a process for making butyrolactones, butanediols, and mixtures thereof by hydrogenating a wide variety of hydrogenatable precursors such as maleic acid, maleic anhydride, succinic acid, succinic acid anhydride, fumaric acid, malic acid, dimethyl succinate, butyrolactones, itaconic acid or mixtures thereof. These precursors can be described as dicarboxylic acids, dicarboxylic acid esters, lactones, or mixtures of said acids, esteres, lactones and/or anhydrides. Preferably, the hydrogenatable precursor is an acid and, most preferably, succinic acid, itaconic acid, maleic acid, or fumaric acid. The methods of the invention are characterized in that they can be oriented, as desired, toward high ratios of butyrolactones to butanediols or vice versa. The catalyst of this invention consists essentially of palladium or combinations thereof with rhenium and at least one support selected from the oxides of titanium, zirconium, and hafnium. Preferably, the catalyst consists essentially of a combination of palladium and rhenium and the support is titanium oxide, and most preferably, the catalyst comprises from about 1 to about 19 weight percent palladium and from about 4 to about 76 weight percent rhenium. The catalyst provides substantially 100% conversion of the precursor, high selectivity to and yield of product, and the advantage of being able to control the product ration of butyrolactone/butanediol by varying the reaction temperature, hydrogen pressure and flow rate of the aqueous reaction medium. Preferably, the process is conducted at a temperature of from about 100°C to about 250°C, and most preferably from about 125°C to about 225°C. Preferably, the process is conducted at a pressure of from about 3.5 MPa (500 psig) to about 27.6 MPa (4000 psig), and most preferably from about 3.5 MPa (500 psig) to about 17.3 MPa (2500 psig). The process is conducted in the presence of an aqueous reaction medium which can be water or an aqueous solution containing water soluble substances such as methanol, ethanol, tetrahydrofuran or 1,4-dioxane. Preferably, the aqueous reaction medium is water. The concentration of precursor is not critical. The precursor can can be employed in dilute solutions to near the maximum solubility level, typically from about 1 to about 50 weight percent. The liquid phase hydrogenation of the invention can be run using conventional apparatus and techniques in a stirred-tank reactor or in a fixed-bed reactor. Hydrogen is fed continuously, generally in considerable stoichiometric excess with no inert diluent gases. Unreacted hydrogen can be returned to the reactor as a recycle stream. The reaction can be run in the batch or continuous mode. The invention is further described in the following examples wherein all parts and percentages are by weight and degrees are Celsius. Catalysts used in the Examples and Comparative Experiments were prepared according to the following general precedure. EXAMPLES Catalyst Preparation The catalysts were prepared by adding 20 g of support to a solution containing the desired amount of PdCl₂, 3 mL of concentrated hydrochloric acid and 15 mL of distilled water. The resultant slurry was stirred for three hours at ambient temperature and dried at 110° for 18 hours. The resulting supported catalyst was then heated in a furnace for one hour at 150° in an atmosphere of helium (flow rate 100 mL/min), followed by heating at 150° for one hour and 300° for three hours in an atmosphere of helium (flow rate 100 mL/min) and hydrogen (flow rate 100 mL/min). While still maintaining the hydrogen helium atmosphere, the catalyst was cooled to ambient temperature and passivated at ambient temperature with an atmosphere of 1.8% oxygen in nitrogen for 18 hours. The resulting reduced catalyst was added to a solution containing the desired amount of ammonium perrhenate and 6 mL of distilled water. The resultant slurry was treated as described above. The catalysts so prepared were granulated to 0.92-1.16 nm (16 to 19 mesh; U.S. Standard Sieve Units) and charged into the reactor employed in the Examples and Comparative Experiments. Prior to start of the liquid feed the granulated catalysts were reduced in the reactor for about two hours each at 100°, 150°, and 200° in a stream of hydrogen. EXAMPLES 1-4 Succinic Acid Hydrogenation A solution of 5% succinic acid and 2% dioxane in water was passed through a fixed bed of 4.12 g of 1% Pd/4% Re on titanium oxide catalyst contained in a glass lined stainless steel reactor (empty reactor volume 6 mL) at the designated liquid flow rate along with hydrogen at a flow rate of 50 mL/minute. The temperature of the reactor was maintained at the desired temperature using a fluidized, barricaded sand bath. Reaction pressure was controlled by means of a back pressure regulator. Product leaving the reactor was analyzed by conventional chromatography to determine selectivity to tetrahydrofuran (THF), 1,4-butanediol (BDO) and gamma-butyrolactone (GBL). Temperature, pressure and liquid feed rate were varied to determine conversion, product split and selectivity. The results ore shown in Table 1. Succinic Acid Hydrogenation Exp. Temp(°) Press. MPa(psig) Flow (mL/hr) THF(%) GBL(%) BDO(%) Conv 1 200 3.5 (500) 22.4 1.74 90.32 7.94 100.00 2 200 6.9(1000) 5.6 8.58 5.00 86.42 98.69 3 150 3.5 (500) 5.6 0.00 89.66 10.34 100.00 4 150 6.9(1000) 11.2 0.00 90.23 9.77 97.70 COMPARATIVE EXPERIMENTS A-B Succinic Acid Hydrogenation The process described in Example 1 was substantially repeated two times except that the reaction mixture was a solution of 5% succinic acid and 2% dioxane in water and the catalyst was 1.70 g of 1% Pd and 4% Re on carbon. The results are shown in Table 2. Succinic Acid Hydrogenation Exp. Temp(°) Press MPa(psig) Flow (ml/hr) THF(%) GBL(%) BDO(%) Conv A 200 6.9(1000) 5.6 81.16 1.23 17.60 89.31 B 200 6.9(1000) 11.2 51.23 21.66 27.11 95.56 EXAMPLES 5-7 Itaconic Acid Hydrogenation The process described in Example 1 was substantially repeated three times except that the reaction mixture was a solution of 4% itaconic acid and 2% dioxane in water and the catalyst was 4.12 g of 1% Pd and 4% Re on titanium oxide. Product leaving the reactor was analyzed by conventional chromatography to determine selectivity to 3- and 4- methyl gamma-butyrolactone (MeGBL(3&4)) and 2-methyl-1,4-butanediol (MeBDO). The Results are shown in Table 3. Itaconic Acid Hydrogenation Exp. Temp(°) Press MPa(psig) Flow (ml/hr) MeGBL(3&4)(%) MeBDO(%) Conv 5 200 3.5 (500) 12 98.58 1.42 81.08 6 175 3.5 (500) 6 98.16 3.84 99.61 7 150 3.5 (500) 3 95.69 4.31 84.06 EXAMPLES 8-11 Maleic Acid Hydrogenation The process described in Example 1 was substantially repeated four times except that the reaction mixture was a solution of 5% maleic acid and 2% dioxane in water, the pressure was 3.5 MPa (500 psig), and the catalysts were as specified in Table 4. In Examples 8 and 9, the catalysts were 1% Pd and 4% Re; in Example 10, the catalyst was 0.5% Pd and 0.5% Re; and in Example 11, the catalyst was 0.5% Pd. The results are shown in Table 4 Maleic Acid Hydrogenation Exp Temp(°) Flow (ml/hr) Catalyst Support THF(%) GBL(%) BDO(%) Conv 8 175 12.0 Pd/Re Zr Oxide 1.04 88.87 10.09 83.1 9 200 18.0 Pd/Re Zr Oxide 1.47 92.22 6.31 92.1 10 300 33.6 Pd/Re Ti Oxide 0.49 98.45 1.06 88.1 11 200 11.2 Pd Ti Oxide 0 98.77 0 45.6

Claims: A process for preparing butyrolactones, butanediols, and mixtures thereof comprising hydrogenating a hydrogenatable precursor in the presence of an aqueous reaction medium and a catalyst consisting essentially of palladium or combinations thereof with rhenium and at least one support selected from the oxides of titanium, zirconium, and hafnium. A process according to Claim 1, wherein the hydrogenatable precursor is an acid. A process according to Claim 2, wherein the hydrogenatable precursor is selected from the group consisting of succinic acid, itaconic acid, maleic acid, or fumaric acid. A process according to Claim 2, wherein the catalyst comprises a combination of palladium and rhenium and the support is titanium oxide. A process according to Claim 4, wherein the catalyst comprises from about 1 to about 19 weight percent palladium and from about 4 to about 76 weight percent rhenium. A process according to Claim 5, wherein the process is conducted at a temperature of from about 100°C to about 250°C. A process according to Claim 6, wherein the process is conducted at a temperature of from about 125°C to about 225°C. A process according to Claim 5, wherein the process is conducted at a pressure of from about 3.5 MPa to about 27.6 MPa. A process according to Claim 8, wherein the process is conducted at a pressure of from about 3.5 MPa to about 17.3 MPa. A process according to Claim 8, wherein the aqueous reaction medium is water.

Inventors: RAO, VELLIYUR NOTT MALLIKARJUNA
Applicants: E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1988
Main classification: C07D307
IPC codes: C07C27, C07C67, C07C29, C07C31, B01J23, C07B61, C07D307, C07D315