Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/10—Preparation of carboxylic acids or their salts, halides or anhydrides by reaction with carbon monoxide
  • C07C51/12—Preparation of carboxylic acids or their salts, halides or anhydrides by reaction with carbon monoxide on an oxygen-containing group in organic compounds, e.g. alcohols
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/36—Preparation of carboxylic acid esters by reaction with carbon monoxide or formates

Definitions

• the present invention relates to a vapor-phase carbonylation method for producing esters and carboxylic acids from reactants including lower alkyl alcohols, lower alkyl alcohol producing compositions, and mixtures thereof. More particularly, the present invention relates to a method for the vapor-phase carbonylation of methanol and/or a methanol producing source to produce acetic acid, methyl acetate and mixtures thereof using a catalyst having a catalytically effective amount of a Group VIII metal selected from platinum or palladium, and tungsten, wherein the metals are associated with a solid carrier material.
• Acetic acid is used in the manufacture of a variety of intermediary and end-products.
• an important derivative is vinyl acetate which can be used as monomer or co-monomer for a variety of polymers.
• Acetic acid itself is used as a solvent in the production of terephthalic acid, which is widely used in the container industry, and particularly in the formation of PET beverage containers.
• Carbonylation of methanol is a well known reaction and is typically carried out in the liquid phase with a catalyst.
• a thorough review of these commercial processes and other approaches to accomplishing the formation of acetyl from a single carbon source is described by Howard et al. in Catalysis Today, 18 (1993) 325-354.
• the liquid phase carbonylation reaction for the preparation of acetic acid using methanol is performed using homogeneous catalyst systems comprising a Group VIII metal and iodine or an iodine-containing compound such as hydrogen iodide and/or methyl iodide.
• Rhodium is the most common Group VIII metal catalyst and methyl iodide is the most common promoter. These reactions are conducted in the presence of water to prevent precipitation of the catalyst.
• U.S. Patent 5,510,524 to Garland et. al. describes a liquid phase carbonylation process for the production of carboxylic acid by carbonylation of an alkyl alcohol and/or reactive derivative by contacting the alcohol with carbon monoxide in a liquid reaction composition which includes an iridium catalyst or rhodium catalyst, an alkyl halide, water and a rhenium promoter.
• a disadvantage of a homogeneous phase carbonylation process is that additional steps are necessary for separating the products from the catalyst solutions, and there are always handling losses of the catalyst. Losses of the metal in the catalyst can be attributed to several factors, such as the plating-out of the active metal onto piping and process equipment thereby rendering the metal inactive for carbonylation purposes and losses due to incomplete separation of the catalyst from the products. These losses of the metal component are costly because the metals themselves are very expensive.
• U.S. Patent 5,144,068 describes the inclusion of lithium in the catalyst system which allows the use of less water in the Rh-I homogeneous process.
• Iridium also is an active catalyst for methanol carbonylation reactions but normally provides reaction rates lower than those offered by rhodium catalysts when used under otherwise similar conditions.
• European Patent Application EP 0 752 406 Al teaches that ruthenium, osmium, rhenium, zinc, cadmium, mercury, gallium, indium, or tungsten improve the rate and stability of the liquid phase Ir-I catalyst system.
• the homogeneous carbonylation processes presently being used to prepare acetic acid provide relatively high production rates and selectivity.
• heterogeneous catalysts offer the potential advantages of easier product separation, lower cost materials of construction, facile recycle, and even higher rates.
• EP 0 120 631 Al and EP 0 461 802 A2 describe the use of special carbons as supports for single transition metal component carbonylation catalysts.
• European Patent Application EP 0 759 419 Al pertains to a process for the carbonylation of an alcohol and/or a reactive derivative thereof.
• EP 0 759419 Al discloses a carbonylation process comprising a first carbonylation reactor wherein an alcohol is carbonylated in the liquid phase in the presence of a homogeneous catalyst system and the off gas from this first reactor is then mixed with additional alcohol and fed to a second reactor containing a supported catalyst.
• the homogeneous catalyst system utilized in the first reactor comprises a halogen component and a Group VIII metal selected from rhodium and iridium.
• the homogeneous catalyst system also may contain an optional co-promoter selected from the group consisting of ruthenium, osmium, rhenium, cadmium, mercury, zinc, indium and gallium.
• the supported catalyst employed in the second reactor comprises a Group VIII metal selected from the group consisting of iridium, rhodium, and nickel, and an optional metal promoter on a carbon support.
• the optional metal promoter may be iron, nickel, lithium and cobalt.
• Drago et al. in U.S. Patent 4,417,077, describe the use of anion exchange resins bonded to anionic forms of a single transition metal as catalysts for a number of carbonylation reactions including the halide-promoted carbonylation of methanol.
• supported ligands and anion exchange resins may be of some use for immobilizing metals in liquid phase carbonylation reactions, in general, the use of supported ligands and anion exchange resins offer no advantage in the vapor phase carbonylation of alcohols compared to the use of the carbon as a support for the active metal component.
• these catalysts are unstable at elevated temperatures making them poorly suited to vapor phase processes.
• Nickel on activated carbon has been studied as a heterogeneous catalyst for the halide-promoted vapor phase carbonylation of methanol, and increased rates are observed when hydrogen is added to the feed mixture.
• Relevant references to the nickel-on-carbon catalyst systems are provided by Fujimoto et al. In Chemistry Letters (1987) 895-898 and in Journal of Catalysis, 133 (1992) 370-382 and in the references contained therein. Liu et al, in Ind. Eng. Chem. Res., 33 (1994) 488-492, report that tin enhances the activity of the nickel-on-carbon catalyst.
• Mueller et al in U.S.
• Patent 4,918,2108 disclose the addition of palladium and optionally copper to supported nickel catalysts for the halide-promoted carbonylation of methanol.
• the rates of reaction provided by nickel-based catalysts are lower than those provided by the analogous rhodium-based catalysts when operated under similar conditions.
• Patent 5,218,140 to Wegman describes a vapor phase process for converting alcohols and ethers to carboxylic acids and esters by the carbonylation of alcohols and ethers with carbon monoxide in the presence of a metal ion exchanged heteropoly acid supported on an inert support.
• the catalyst used in the reaction includes a polyoxometalate anion in which the metal is at least one of a Group V(a) and VI(a) is complexed with at least one Group VIII cation such as Fe, Ru, Os, Co, Rh, Ir, Ni, Pd or Pt as catalysts for the halide-free carbonylation of alcohols and other compounds in the vapor phase.
• the general formula of a preferred form of the heteropoly acid used in the practice of the process is M[Q 12 PO 40 ] where M is a Group VIII metal or a combination of Group VIII metals, Q is one or more of tungsten, molybdenum, vanadium, niobium, chromium, and tantalum, P is phosphorous and O is oxygen.
• U.S. Patent 5,900,505 to Tustin et al. describes a vapor-phase carbonylation catalyst having iridium and at least one second metal selected from ruthenium, molybdenum, tungsten, palladium, platinum and rhenium deposited on a catalyst support material.
• U.S. Patent 5,414,161 to Uhm et al. describes a process for the production of ethanol using gas phase carbonylation of methanol.
• the catalyst used in the process includes a rhodium compound and a second metallic component selected from an alkali metal, alkaline earth metal or a transition metal deposited on a support material.
• the present invention is a method for the vapor-phase carbonylation of reactants comprising lower alkyl alcohols, lower alkyl alcohol generating compositions, and mixtures thereof.
• the method includes the step of contacting the reactants under vapor-phase carbonylation reaction conditions with a heterogeneous catalyst having a catalytically effective amount of a Group VIII metal selected from platinum or palladium and/or their respective metal containing compound, and tungsten and/or tungsten containing compound.
• the metals are associated with a solid carrier material which, desirably, is inert to the carbonylation reaction.
• the method also includes contacting the reactants, in the presence of the solid catalyst, with a vaporous halide promoter.
• the term "associated with” includes any manner that permits the platinum or palladium metal and/or a compound containing the metal, such as a salt thereof, and the tungsten metal and/or a tungsten containing compound to reside on or in the solid support.
• the metals may be associated with the solid support include impregnating, immersing, spraying, and coating the support sequentially with a solution containing the Group VIII metal and then with a tungsten containing solution.
• the Group VIII and tungsten metals may be associated with the solid support by impregnating, immersing, spraying, or coating the support with a solution containing a mixture of the Group VIII metal and tungsten.
• a vapor-phase carbonylation method for the continuous production of carboxylic acids and esters by contacting lower alkyl alcohols, and lower alkyl alcohol generating compositions, such as ether and/or ester derivatives of the alcohol, and ester-alcohol mixtures, and carbon monoxide with a solid supported catalyst.
• the solid supported catalyst includes an effective amount of a Group VIII metal selected from platinum or palladium and/or a compound containing the respective metal and tungsten and/or a tungsten containing compound wherein the metals are associated with a solid support material.
• the solid support material is inert to the carbonylation reaction.
• the reactant in the practice of a vapor-phase carbonylation process, contacts the solid supported catalyst in a carbonylation zone of a carbonylation reactor.
• the reactant is fed in conjunction with a vaporous halide promoter.
• the present invention provides for the vapor-phase carbonylation of methanol and/or a methanol generating source for the continuous production of acetic acid, methyl acetate or mixtures thereof.
• the vapor-phase carbonylation process is operated at temperatures above the dew point of the reactants and products mixture, i.e., the temperature at which condensation occurs.
• the dew point is a complex function of dilution (particularly with respect to non-condensable gases such as unreacted carbon monoxide, hydrogen, or inert diluent gas), product composition, and pressure, the process may still be operated over a wide range of temperatures, provided the temperature exceeds the dew point of the reactants and product effluent. In practice, this generally dictates a temperature range of about 100°C to about 500°C, with temperatures of about 100°C to about 350°C being preferred and temperatures of about 150°C to 275°C being particularly useful.
• the useful pressure range is limited by the dew point of the product mixture.
• a wide range of pressures may be used, e.g., pressures in the range of about 0.1 to 100 bars absolute (bara).
• the process preferably is carried out at a pressure in the range of about 1 to 50 bars absolute, most preferably, about 3 to 30 bar absolute.
• Suitable feed stocks which may be carbonylated using the catalyst of the present invention include lower alkyl alcohols, lower alkyl alcohol producing compositions, such as ether and ester derivatives of the lower alkyl alcohol which generate a lower alkyl alcohol under vapor-phase carbonylation conditions, and mixtures thereof.
• feed stocks include alcohols and ethers in which an aliphatic carbon atom is directly bonded to an oxygen atom of either an alcoholic hydroxyl group in the compound or an ether oxygen in the compound and may further include aromatic moieties.
• the feed stock is one or more lower alkyl alcohols having from 1 to 10 carbon atoms and preferably having from 1 to 6 carbon atoms, alkane polyols having 2 to 6 carbon atoms, alkyl alkylene polyethers having 3 to 20 carbon atoms and alkoxyalkanols having from 3 to 10 carbon atoms.
• the most preferred reactant is methanol.
• methanol is the preferred feed stock to use with the solid supported catalyst of the present invention and is normally fed as methanol, it can be supplied in the form of a combination of materials which generate methanol. Examples of such materials include (i) methyl acetate and water and (ii) dimethyl ether and water.
• both methyl acetate and dimethyl ether are formed within the reactor and, unless methyl acetate is the desired product, they are recycled with water to the reactor where they are converted to acetic acid.
• the presence of water in the gaseous feed mixture is not essential when using methanol, the presence of some water is desirable to suppress formation of methyl acetate and/or dimethyl ether.
• the molar ratio of water to methanol can be 0:1 to 10:1, but preferably is in the range of 0.01 :1 to 1 :1.
• the amount of water fed usually is increased to account for the mole of water required for hydrolysis of the methanol alternative. Accordingly, when using either methyl acetate or dimethyl ether, the mole ratio of water to ester or ether is in the range of 1 : 1 to 10:1, but preferably in the range of 1 : 1 to 3: 1.
• the mole ratio of water to ester or ether is in the range of 1 : 1 to 10:1, but preferably in the range of 1 : 1 to 3: 1.
• acetic acid it is apparent that combinations of methanol, methyl ester, and/or dimethyl ether are equivalent, provided the appropriate amount of water is added to hydro lyze the ether or ester to provide the methanol reactant.
• the catalyst When the catalyst is used in a vapor-phase carbonylation process to produce methyl acetate, no water should be added and dimethyl ether becomes the preferred feed stock. Further, when methanol is used as the feed stock in the preparation of methyl acetate, it is necessary to remove water. However, the primary utility of the catalyst of the present invention is in the manufacture of acetic acid.
• the solid supported catalyst includes a catalytically effective amount of platinum or palladium associated with a solid support material.
• the compound or form of platinum or palladium used to prepare the solid supported catalyst generally is not critical and the catalyst may be prepared from any of a wide variety of platinum or palladium containing compounds.
• platinum or palladium compounds may be alone or contain combinations of halide, trivalent nitrogen, organic compounds of trivalent phosphorous, carbon monoxide, hydrogen, and 2,4-pentanedione. Such materials are available commercially and may be used in the preparation of the catalysts utilized in the present invention.
• the oxides of platinum or palladium may be used if dissolved in the appropriate medium.
• the platinum or palladium is a salt of one of their respective chlorides.
• a preferred platinum or palladium is any of the various salts of hexachloroplatinate (IV) or a solution of platinum dichloride in either aqueous HC1 or aqueous ammonia.
• suitable materials include platinum chloride or hexachloroplatinate complexes.
• use of the preferred platinum or palladium complexes should be comparable on the basis of cost, solubility, and performance.
• the amount of platinum or palladium, as metal, on the support can vary from about 0.01 weight percent to about 10 weight percent, with from about 0.1 weight percent to about 2 weight percent platinum or palladium being preferred based on the total weight of the solid supported catalyst.
• the solid supported catalyst also includes a predetermined amount of tungsten as a second metal component.
• the form of tungsten used to prepare the catalyst generally is not critical.
• the solid phase component of the catalyst may be prepared from a wide variety of tungsten containing compounds.
• tungsten compounds containing halides, a wide variety of organic (akyl and aryl) carboxylate salts, carbonyls, and alkyl or aryl groups bound to tungsten, as well as various mixtures thereof, are well known, are available commercially, and may be used in the preparation of the catalysts utilized in the present invention.
• tungsten oxides which may be used if dissolved in the appropriate medium. Based on its availability, cost, lower toxicity, and high solubility in water (the preferred solvent medium) the preferred source of tungsten is as the ammonium tungstate.
• the content of tungsten, as metal, on the support can vary over a wide range, for example from about 0.01 to 10 weight percent tungsten based on the total weight of the solid supported catalyst.
• the preferred amount of tungsten in the catalyst is from about 0.1 to 5 weight percent of tungsten based on the total weight of the solid supported catalyst.
• the solid support useful for acting as a carrier for the platinum or palladium and tungsten consists of a porous solid of such size that it can be employed in fixed or fluidized bed reactors.
• the support materials can have a size of from about 400 mesh per inch to about Vi inch.
• the support is carbon, including activated carbon, having a surface area greater than about 200 square meters/gram (m 2 /g) .
• Activated carbon is well known in the art and may be derived from coal or peat having a density of from about 0.03 grams/cubic centimeter (g/cm 3 ) to about 2.25 g/cm 3 .
• the carbon can have a surface area of from about 200 square meters/gram to about 1200 m 2 /g.
• solid support materials may be used, either alone or in combination, in accordance with the present invention include pumice, alumina, silica, silica-alumina, magnesia, diatomaceous earth, bauxite, titania, zirconia, clays, magnesium silicate, silicon carbide, zeolites, and ceramics.
• the shape of the solid support is not particularly important and can be regular or irregular and include extrudates, rods, balls, broken pieces and the like disposed within the reactor.
• the preparation of the solid support catalyst is carried out by preferably dissolving or dispersing the platinum or palladium and tungsten metal components in a suitable solvent.
• the solid support carrier material is then contacted with the metal containing solutions.
• the Group VIII metal, i.e., platinum or palladium, and tungsten are associated with the support material as a result of soluble impregnation of the metals which may result in either a salt of the metals, an oxide of the metals, or as a free metal deposited on the support.
• Various methods of contacting the support material with the platinum or palladium and tungsten may be employed.
• a solution containing the platinum or palladium can be admixed with a solution containing tungsten prior to impregnating the support material.
• the aforementioned individual solutions can be impregnated separately into or associated with the support material prior to impregnating the support material with the second metal containing solution.
• the tungsten containing solution may be deposited on a previously prepared catalyst support having the platinum or palladium component already incorporated thereon. Desirably, in this alternative embodiment, the support is dried prior to contacting the second solution.
• the platinum or palladium and tungsten may be associated with the support material in a variety of forms.
• slurries of the metals can be poured over the support material, sprayed on the support material or the support material may be immersed in solutions containing excess platinum or palladium and tungsten with the excess being subsequently removed using techniques known to those skilled in the art.
• the solvent is evaporated so that at least a portion of the platinum or palladium and tungsten is associated with the solid support. Drying temperatures can range from about 100°C to about 600°C. One skilled in the art will understand that the drying time is dependent upon the temperature, humidity, and solvent. Generally, lower temperatures require longer heating periods to effectively evaporate the solvent from the solid support.
• the liquid used to deliver the platinum or palladium and tungsten in the form a solution, dispersion, or suspension is desirably a liquid having a low boiling point of from about 10 °C to about 140°C.
• suitable solvents include carbon tetrachloride, benzene, acetone, methanol, ethanol, isopropanol, isobutanol, pentane, hexane, cyclohexane, heptane, toluene, pyridine, diethylamine, acetaldehyde, acetic acid, tetrahydrofuran and preferably, water.
• the method further includes contacting the reactants, in the presence of the solid catalyst, with a vaporous halide promoter selected from chlorine, bromine and iodine compounds.
• a vaporous halide promoter selected from chlorine, bromine and iodine compounds.
• the vaporous halide is selected from bromine and iodine compounds that are vaporous under vapor-phase carbonylation conditions of temperature and pressure.
• Suitable halides include hydrogen halides such as hydrogen iodide and gaseous hydriodic acid; alkyl and aryl halides having up to 12 carbon atoms such as, methyl iodide, ethyl iodide, 1 -iodopropane, 2-iodobutane, 1-iodobutane, methyl bromide, ethyl bromide, benzyl iodide and mixtures thereof.
• the halide is a hydrogen halide or an alkyl halide having up to 6 carbon atoms.
• Non-limiting examples of preferred halides include hydrogen iodide, methyl iodide, hydrogen bromide, methyl bromide and mixtures thereof.
• the halide may also be a molecular halide such as I 2 , Br 2 , or Cl 2 .
• the halide is introduced into the carbonylation reactor with the reactants.
• the ultimate active species of the platinum or palladium and tungsten may exist as one or more coordination compounds or a halide thereof.
• a gaseous mixture having at least one reactant of a lower alkyl alcohol, and/or a lower alkyl alcohol generating composition; carbon monoxide; and a halide are fed to a carbonylation reactor containing the solid supported platinum or palladium and tungsten catalyst described above.
• the reactant, in the vapor phase is allowed to contact the solid supported catalyst.
• the reactor is maintained under vapor-phase carbonylation conditions of temperature and pressure.
• the vaporous product is then recovered. If it is desired to increase the proportion of acid produced, the ester may be recycled to the reactor together with water or introduced into a separate reactor with water to produce the acid in a separate zone.
• the vapor-phase carbonylation method of the present invention may be used for making acetic acid, methyl acetate or a mixture thereof.
• the process includes the steps of contacting a gaseous mixture comprising methanol or a methanol generating composition, carbon monoxide and a vaporous halide promoter with the solid supported Group VIII metal and tungsten catalyst in a carbonylation zone and recovering a gaseous product from the carbonylation zone.
• the molar ratio of methanol or methanol equivalents to halide present to produce an effective carbonylation ranges from about 1 : 1 to 10,000: 1 , with the preferred range being from about 5:1 to about 1000:1.
• the carbon monoxide can be a purified carbon monoxide or include other gases.
• the carbon monoxide need not be of a high purity and may contain from about 1 % by volume to about 99 % by volume carbon monoxide, and preferably from about 70 % by volume to about 99 % by volume carbon monoxide.
• the remainder of the gas mixture may include such gases as nitrogen, hydrogen, carbon dioxide, water and paraffinic hydrocarbons having from one to four carbon atoms.
• hydrogen is not part of the reaction stoichiometry, hydrogen may be useful in maintaining optimal catalyst activity.
• the preferred ratio of carbon monoxide to hydrogen generally ranges from about 99:1 to about 2: 1, but ranges with even higher hydrogen levels are also likely to be useful.
• the impregnated catalyst was then transferred to a quartz tube measuring 106 cm long by 25 mm outer diameter.
• the quartz tube was thereafter placed in a three-element electric tube furnace so that the mixture was located in the approximate center of the 61 cm long heated zone of the furnace.
• Nitrogen was continuously passed through the catalyst bed at a rate of 100 standard cubic centimeters per minute.
• the tube was heated from ambient temperature to 300°C over a 2 hour period, held at 300°C for 2 hours and then allowed to cool back to ambient temperature.
• a second solution was prepared by dissolving 0.331 grams of ammonium tungstate (1.17 mm of W) in 30 mL of distilled water which had been heated to 50°C to allow complete dissolution of the ammonium tungstate. This was then added to the Pt impregnated catalyst prepared above. The catalyst was dried and transferred to a quartz tube following the procedure described above.
• the solid supported catalyst in accordance with the present invention contained 1.09% Pt, 1.03% W, and had a density of 0.57 g /mL.
• a second catalyst was prepared by dissolving 0.331 grams of ammonium tungstate (1.17 mmol) in 30 mL of distilled water which was heated to 50°C to allow complete dissolution of the ammonium tungstate. This solution was then added to 20.0 grams of 12 X 40 mesh activated carbon granules (available from Calgon) contained in an evaporating dish. The activated carbon granules had a BET surface area in excess of 800 m 2 /g. The mixture was then dried and placed in a quartz tube as described above in Example 1.
• a second solution prepared by dissolving 0.207 grams of palladium chloride (1.16 mmol of Pd) in 15 mL of distilled water and 15 mL of 11.6 M HC1. This was then added to the tungsten impregnated catalyst prepared above. The mixture was again heated using the steam bath with continuous stirring until it became free flowing and then transferred to a quartz tube following the procedure described above.
• the quartz tube was thereafter placed in a three-element electric tube furnace so that the mixture was located in the approximate center of the 61 cm long heated zone of the furnace. Nitrogen was continuously passed through the catalyst bed at a rate of 100 standard cubic centimeters per minute. The tube was heated from ambient temperature to 300°C over a 2 hour period, held at 300°C for 2 hours and then allowed to cool back to ambient temperature.
• the catalyst (Comparative Catalyst C-I) contained 1.10 % Pt and had a density of 0.57 g / mL.
• a second comparative catalyst (Comparative Catalyst C-II) was prepared following the procedure of Example 1 above except that 0.206 grams of ammonium molybdate (1.17 mmol) were used in place of ammonium tungstate. The ammonium molybdate dissolved at room temperature and did not require warming to 50°C.
• COMPARATIVE CATALYST EXAMPLE III A third comparative catalyst (Comparative Catalyst C-III), was prepared following the procedure of Example 1 above except that 0.288 grams of chromium (III) acetate (1.117 mmol) were used in place of ammonium tungstate.
• a fourth comparative catalyst (Comparative Catalyst C-IV), was prepared following the procedure of Comparative Catalyst Example 1 above except that 290 mg of nickelous acetate tetrahydrate (1.18 mmol of Ni) was used in place of the dihydrogen hexachloroplatinate.
• the catalyst contained 0.34% Ni.
• a fifth comparative catalyst (Comparative Catalyst C-V), was prepared by dissolving 0.331 grams of ammonium tungstate (1.17 mmol of W) in 30 mL of distilled water heated to 50°C to allow complete dissolution of the ammonium tungstate. This solution was added to 20 grams of Davison Silica Grade 57, (available from W.R. Grace) contained in an evaporating dish. The silica had a BET surface area of 300 m /g. This mixture was dried using a steam bath and continuously stirred until the support granules became free flowing. The impregnated catalyst was then transferred to a quartz tube measuring 106 cm long by 25 mm outer diameter.
• the quartz tube was thereafter placed in a three-element electric tube furnace so that the mixture was located in the approximate center of the 61 cm long heated zone of the furnace. Nitrogen was continuously passed through the catalyst bed at a rate of 100 standard cubic centimeters per minute. The tube was heated from ambient temperature to 300°C over a 2 hour period, held at 300°C for 2 hours and then allowed to cool back to ambient temperature.
• a second solution was prepared by dissolving 0.579 grams of dihydrogen hexachloroplatinate (IV) (1.16 mmol of Pt) in 30 mL of distilled water. This was then added to the tungsten impregnated catalyst above. The catalyst was dried and transferred to a quartz tube following the procedure described above.
• COMPARATIVE CATALYST EXAMPLE VI A sixth comparative catalyst (Comparative Catalyst C-VI) was prepared following the procedure of Example 1 except that 20 g of ⁇ -alumina (Engelhard ⁇ - Alumina Al- 3920T) having a BET surface area of 3-5 m 2 /g was used in place of the activated carbon.
• a seventh comparative catalyst (Comparative Catalyst C-VII) was prepared following the procedure of Example 2 except that 0.29 grams of nickelous acetate tetrahydrate dissolved in 30 mL of distilled water in place of the solution of palladium chloride in 1:1 concentrated HC1: water. The catalyst had a density of 0.57 g / mL.
• COMPARATIVE CATALYST EXAMPLE VIII An eighth comparative catalyst (Comparative Catalyst C-VIII) was prepared following the procedure of Comparative Example I above except 207 mg of palladium chloride (1.17 mmol of Pd) was used in place of the dihydrogen hexachloroplatinate and an additional 10 mL of concentrated HC1 was added to solubilize the palladium chloride. This procedure gave a catalyst which contained. The catalyst contained 0.61% Pd and had a density of 0.57 g / mL.
• a ninth comparative catalyst (Comparative Catalyst C-IX) was prepared following the procedure of Comparative Catalyst Example I above except 418 mg iridium trichloride hydrate (1.17 mmol of Ir) of was used in place of the dihydrogen hexachloroplatinate.
• the catalyst contained 1.10 weight % Ir.
• the reactor system consisted of a 800 to 950 mm (31.5 and 37 inch) section of 6.35 mm ( l A inch) diameter tubing constructed of Hastelloy C alloy.
• the upper portion of the tube constituted the preheat and reaction (carbonylation) zones which were assembled by inserting a quartz wool pad 410 mm from the top of the reactor to act as support for the catalyst, followed sequentially by (1) a 0.7 gram bed of fine quartz chips (840 microns), (2) 0.5 gram of one of the catalysts prepared as described in the preceding examples, and (3) an additional 6 grams of fine quartz chips.
• the top of the tube was attached to an inlet manifold for introducing liquid and gaseous feeds.
• the gases were fed using Brooks flow controllers and liquids were fed using a high performance liquid chromatography pump.
• the gaseous products leaving the reaction zone were condensed using a vortex cooler operating at 0-5°C.
• the product reservoir was a tank placed downstream from the reactor system.
• the pressure was maintained using a Tescom 44-2300 Regulator on the outlet side of the reactor system and the temperature of the reaction section was maintained using heating tape on the outside of the reaction system.
• Feeding of hydrogen and carbon monoxide to the reactor was commenced while maintaining the reactor at a temperature of 240°C and a pressure of 17.2 bara (250 psia).
• the flow rate of hydrogen was set at 25 standard cubic cm. per minute (cc/min) and the carbon monoxide flow rate was set at 100 cc/min.
• the reactor section was maintained under these conditions for 1 hour or until the temperature and pressure had stabilized
• “Production Rate” is the moles of Acetyl Produced per liter of catalyst volume per hour during each increment of Time (Time Increment), i.e., the time of operation between samples.
• the formula for determining moles of Acetyl Produced per liter of catalyst volume per hour (space time yield) is determined as follows:
• Catalyst 2 and Comparative Catalysts C-I through C-IX were used in the carbonylation of methanol using the same procedure and parameters as described above.
• the Production Rate expressed in terms of moles of Acetyl Produced per kilogram of catalyst per hour and moles per liter of catalyst volume per hour, for each of the catalysts is shown in Table 3 below.
• the solid supported catalyst having platinum and tungsten on activated carbon is significantly more active than a catalyst derived from platinum alone. Moreover, it is surprising that promotional effect of tungsten is unique among the Group 6 (Cr, Mo, W) metals.
• Carbonylation example 2 when compared to comparative example C-IV, demonstrates that there is a substantial promotion of palladium catalyzed reactions upon the addition of tungsten as well.
• the combination of platinum with tungsten is superior to comparative catalyst C-IX wherein iridium is the active metal.
• the catalyst of the present invention exhibits commercially acceptable carbonylation rates in the substantial absence of other Group VIII compounds and particularly compounds containing rhodium, rhenium and iridium.

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