GB406345A - Improvements in or relating to the production of formic acid - Google Patents

Abstract

Formic acid is produced by reaction of carbon monoxide with steam in presence of a catalyst comprising a non-volatile acidic oxide not combined with a base or an acid salt derived from an acidic oxide. The acidic oxide may be an oxide of phosphorus, arsenic, tungsten, molybdenum, uranium, chromium, vanadium, titanium, boron, silicon or zirconium, and the acid salts may be primary or secondary phosphates, tungstates or molybdates of zinc, calcium, magnesium, sodium, potassium, copper, cerium or thorium. Mutually combined acid oxides may also be used, such as phosphomolybdic acid, phosphotungstic acid, phosphosilicic acid, silico tungstic acid, silicomolybdic acid, chromium vanadate, or vanadium molybdate. The use of catalysts containing substantial quantities of iron, nickel or cobalt or their compounds is excluded. Carriers such as activated charcoal, fullers earth or kieselguhr may be employed, and inert gases such as nitrogen or carbon dioxide may be present. Pressure is preferably employed, and may be 25--900 atmospheres. The apparatus may be lined with glass or internally coated with chromium or silver or it may be made of acid resisting alloys of molybdenum, cobalt, tungsten, chromium, manganese or nickel. In the examples mixtures of carbon monoxide and steam are passed over (1) an acid zinc phosphate prepared by adding zinc oxide to aqueous phosphoric acid, impregnating a support such as activated charcoal with the solution, and drying at 120 DEG C.; (2) primary calcium phosphate; (3) silicotungstic acid prepared by mixing solutions of sodium tungstate and sodium silicate in equivalent proportions, the mixture being acidified with hydrochloric acid and extracted with ether, the ether being evaporated from the extract and the residue dissolved in water and used to impregnate silica gel; (4) silicomolybdic acid. The pressures employed are respectively 700, 200, 700, and 200 atmospheres and the temperature 325 DEG C. Specifications 29165/10, and 308,666 (as open to inspection under Sect. 91), [both in Class 2 (iii)], are referred to.ALSO:Formic acid is produced by reaction of carbon monoxide with steam in presence of a catalyst comprising a non-volatile acidic oxide not combined with a base or an acid salt derived from an acidic oxide. The acidic oxide may be an oxide of phosphorus, arsenic, tungsten, molybdenum, uranium, chromium, vanadium, titanium, boron, silicon or zirconium, and the acid salts may be primary or secondary phosphates, tungstates or molybdates of zinc, calcium, magnesium, sodium, potassium, copper, cerium or thorium. Mutually combined acid oxides may also be used, such as phosphomolybdic acid, phosphotungstic acid, phosphosilicic acid, silicotungstic acid, silicomolybdic acid, chromium vanadate, or vanadium molybdate. The use of catalysts containing substantial quantities of iron, nickel or cobalt or their compounds is excluded. Carriers such as activated charcoal, fuller's earth or kieselguhr may be employed, and inert gases such as nitrogen or carbon dioxide may be present. Pressure is preferably employed, and may be 25--900 atmospheres. The apparatus may be lined with glass or internally coated with chromium or silver or it may be made of acid resisting alloys of molybdenum, cobalt, tungsten chromium, manganese or nickel. In the examples, mixtures of carbon monoxide and steam are passed over (1) an acid zinc phosphate prepared by adding zinc oxide to aqueous phosphoric acid, impregnating a support such as activated charcoal with the solution, and drying at 120 DEG C.; (2) primary calcium phosphate; (3) silicotungstic acid prepared by mixing solutions of sodium tungstate and sodium silicate in equivalent proportions, the mixture being acidified with hydrochloric acid and extracted with ether, the ether being evaporated from the extract and the residue dissolved in water and used to impregnate silica gel; (4) silicomolybdic acid. The pressures employed are respectively 700, 200, 700, and 200 atmospheres and the temperature 325 DEG C. Specifications 29165/10 and 308,666 (as open to inspection under Sect. 91), [both in [Class 2 (iii)], are referred to.