Patent GB-714839-A (GB)
Title: Process for the hydrogenation of carbon monoxide
Filed: 1951-03-22
Abstract: Synthesis products rich in oxygenated compounds are obtained by contacting a synthesis gas containing at least 1.2, preferably 1.5-2 vols. of hydrogen per vol. of carbon monoxide under synthesis conditions with a precipitated iron catalyst containing more than 5 per cent, preferably 8-12 per cent by weight (as K2O) based on the total iron of alkali metal compounds as herein defined, the catalyst being unsupported or containing not more than 20 per cent by weight of supporting material based on the total iron and being used as a fixed bed or a suspension in a liquid medium.  The alkali metal compounds are those having an alkaline reaction or decomposed under the reaction conditions to alkaline reacting compounds, for example hydroxides, carbonates, and salts of organic acids such as acetates and oxalates.  Copper, silver, metals of Groups 2, 5, 6 or 7 or their oxides may be present as promoters.  Synthesis temperatures of 150-225 DEG  C. may be used.  Where the alkali metal is potassium, esters are largely formed while sodium gives alcohols.  The catalyst is made by precipitating hot solutions of the salts with alkali, e.g. at a pH of 9-11.  Restricted washing to leave the required alkali or complete washing followed by impregnation with the necessary alkali compound may be employed.  The latter is preferred where lithium, rubidium or caesium or several alkali metals are used. The catalyst is dried and moulded under high pressure, small amounts of inert supports being incorporated if desired.  The unreduced threads or filaments should be about 3-8 mm.  Drying is effected at 80-150 DEG C., preferably to a water content of 4-7 per cent.  Reduction is preferably with hydrogen or ammonia synthesis mixtures until more than 60, preferably more than 80 per cent of the iron is present as metal.  Temperature is 250-350 DEG  C. and linear speed of the gases 30-150 cm./sec. at N.T.P.  High throughput of synthesis gas, e.g. 200-400 vols./vol./hr. may be used.  Pressure may be 10-100 kg./sq. cm.  Multistage operation with intermediate removal of carbon dioxide is advantageous. Recycling with 1-10 vols. recycle gas per vol. fresh gas may be used.  Examples describe the preparation of catalysts containing 100 parts Fe, 5 or 10 Cu, and 10 CaO and/or 10 kieselguhr by precipitation with sodium carbonate, washing to a residual alkali content of 8.4 per cent (as K2O) or impregnating with potassium or sodium carbonate or hydroxide to give a final alkali content of 7 or 10 per cent, and the use of these in the synthesis of products containing oxygenated compounds e.g. alcohols and esters.ALSO:A precipitated iron catalyst containing more than 5, preferably 3-12 per cent. by weight (as K2O) based on the total iron of alkali metal compounds as herein defined, the catalyst being unsupported or containing not more than 20 per cent. by weight of supporting material based on the total iron is used as a fixed bed or a suspension in a liquid medium for syntheses from CO and H2.  The alkali metal compounds are those having an alkaline reaction or decomposed under the reaction conditions to alkaline reacting compounds, for example hydroxides, carbonates, and salts of organic acids such as acetates and oxalates.  Copper, silver, metals of Groups 2, 5, 6 or 7 or their oxides may be present as promoters. Where the alkali metal is potassium, esters are largely formed while sodium gives alcohols.  The catalyst is made by precipitating hot solutions of the salts with alkali, e.g. at a pH of 9-11.  Restricted washing to leave the required alkali or complete washing followed by impregnation with the necessary alkali compound may be employed.  The latter is preferred where lithium, rubidium or caesium or several alkali metals are used. The catalyst is dried and moulded under high pressure, small amounts of inert supports being incorporated if desired.  The unreduced threads or filaments should be about 3-8 mm. Drying is effected at 80-150 DEG  C., preferably to a water content of 4-7 per cent.  Reduction is preferably with hydrogen or ammonia synthesis mixtures until more than 60, preferably more than 80 per cent. of the iron is present as metal.  Temperature is 250-350 DEG C., and linear speed of the gases 30-150 cm/sec. at N.T.P.  Examples describe the preparation of catalysts containing 100 parts Fe, 5 or 10 Cu, and 10 CaO and/or 10 kieselguhr by precipitation with sodium carbonate, washing to a residual alkali content of 8.4 per cent. (as K2O) or impregnating with potassium or sodium carbonate or hydroxide to give a final alkali content of 7 or 10 per cent.