Patent GB-767712-A (GB)
Title: Process for the catalytic hydrogenation of carbon monoxide
IPC: C07C1/04
Filed: 1953-01-27
Abstract: A gas containing CO and H2 in synthesis proportions is contacted at 150-300 DEG , preferably 190-250 DEG  C., and up to 100, preferably 10-50 atmos., with a precipitated and reduced catalyst containing copper and a metal of the iron group, in a proportion by weight between 50 : 50 and 95 : 5, and an alkali metal compound which, calculated as K2O, is present up to not more than 50 per cent by weight of the iron group metal, the catalyst having been precipitated under such conditions that the pH of the solution upon completion of the precipitation was from 6-11, preferably 7-9.  The catalyst may contain other promoters, e.g. alkaline earths, oxides of Zn, Cr, Al, and Th, and supports, e.g. alumina, silica, and activated clays. Bivalent copper salts are preferably used.  Precipitation is effected at about 80-110 DEG  C., suitably by adding the metal salt solutions to boiling alkali metal hydroxide or carbonate.  The precipitate is washed to remove excess alkali which should be less than 5 per cent, as K2O, of the iron group metal to yield hydrocarbon-rich products but may reach 50 per cent when oxygenated products, particularly alcohols, are desired.  Subsequent impregnation with alkali may be effected.  For hydrocarbon synthesis, treatment with alkali metal salts of phosphoric, silicic, or boric acids is effective, the ratio of K2O to P2O5 or B2O3 being about 1 : 1 and of K2O to SiO2 between 1 : 3 and 1 : 6.  The catalyst is dried, preferably to 3-8 per cent water, and reduced at 150-300 DEG  C. with high gas flow rates of 30-200 cm./sec., and using thick layers, preferably of 5-12 metres. The reduction value is preferably below 40 per cent for hydrocarbon, and above 60 per cent for oxygenated product synthesis.  The synthesis gas may be passed at a rate of 500 l. or more/l. of catalyst/hr., using catalyst layers of 10 m. or more.  Recycling or multistage operation with CO2 removal may be used. Multi-component cooling media may be used to provide temperature gradients.  In examples: (1) a catalyst having a Cu : Fe ratio of 75 : 25 is precipitated from a solution of the nitrates at a pH of 9-9.2, impregnated with K2CO3 to give 32 per cent K2O based on iron and used, after reduction with H2+N2, to treat water gas at 200 DEG  C. and 30 atmos. With a gas load of 100 l./l. catalyst/hr. the product is largely esters and alcohols.  By increasing the flow 2-, 3-, 4- and 5-fold with temperature rising gradually to 242 DEG  C., ester, alcohol, and hydrocarbon formation is varied; (2) the Cu : Fe ratio is 100 : 10, and K2O content is 8 per cent based on copper; (3) Cu : Fe is 1 : 1, the pH after precipitation 7.1, and K2CO3 content, as K2O, is 8 per cent of the iron.  Synthesis gas of varying CO and H2 content with residual CO2, N2, and CH4 is converted to yield varying proportions of esters and alcohols; (4) Cu : Fe is 75 : 25 and sec. potassium phosphate is incorporated to give the same K2O : Fe ratio.ALSO:A precipitated and reduced catalyst containing copper and a metal of the iron group, in a proportion by weight between 50:50 and 95:5, and an alkali metal compound which, calculated at K2O, is present up to not more than 50 per cent by weight of the iron group metal, is prepared by precipitation under such conditions that the pH of the solution upon completion of the precipitation is from 6-11, preferably 7-9.  The catalyst is used for the synthesis of hydrocarbons and oxygenated products from CO and H2 (see Group IV(b)).  It may contain other promoters, e.g. alkaline earths, oxides of Zn, Cr, Al, and Th, and supports, e.g. alumina, silica, and activated clays.  Bivalanet copper salts are preferably used. Precipitation is effected at about 80-110 DEG C., suitably by adding the metal salt solutions to boiling alkali metal hydroxide or carbonate.  The precipitate is washed to remove excess alkali which should be less than 5 per cent, as K2O, of the iron group metal to yield hydrocarbon-rich products but may reach 50 per cent when oxygenated products, particularly alcohols are desired.  Subsequent impregnation with alkali may be effected.  For hydrocarbon synthesis, treatment with alkali metal salts of phosphoric, silicic or boric acids is effective, the ratio of K2O to P2O5 or B2O3 being about 1:1 and of K2O to SiO2 be tween 1:3 and 1:6.  The catalyst is dried, preferably to 3-8 per cent water and reduced at 150-300 DEG C. with high gas flow rates of 30-200 cm-sec., and using thick layers, preferably of 5-12 metres. The reduction value is preferably below 40 per cent for hydrocarbon, and above 60 per cent for oxygenated product syntheseis.  In Examples (1) a catalyst having a Cu:Fe ratio of 75:25 is precipitated from a solution of the nitrates at a pH of 9-9.2, impregnated with K2CO3 to give 32 per cent K2O based on iron and used, after reduction with H2 + N2, to treat water gas at 200 DEG C. and 30 atoms; (2) the Cu:Fe ratio is 100:10, and K2O content is 8 per cent based on copper; (3) Cu:Fe is 1:1, the pH after precipitation 7.1, and K2CO3 content, as K2O, is 8 per cent of the iron; (4) Cu:Fe is 75:25 and sec. potassium phosphate is incorporated to give the safe K2O:Fe ratio.