GB1032518A - The hydrofluorination of acetylenic hydrocarbons - Google Patents

Abstract

A process for hydrofluorinating acetylenic hydrocarbons comprises contacting a gaseous mixture of hydrofluoric acid and at least one acetylenic hydrocarbon with a catalyst which comprises one or more mercury derivatives laid on a carrier of porous sintered alumina. The gaseous mixture contains 0.8 to 2 moles of hydrofluoric acid per mole of acetylenic hydrocarbon and the porous sintered alumina has a total porosity of between 5 and 50 cm.3 per 100 g. of alumina and a specific surface area of between 0.01 m2/g. and 1 m2/g. The reaction is conducted at a temperature of from 25 DEG to 150 DEG C. and a pressure of 0.2 atm. to 10 atm. A gaseous oxygenous derivative of nitrogen may be added to the acetylenic hydrocarbon or to the gaseous mixture specified above. Examples describe the conversion of acetylene to vinyl fluoride, 1,1-difluoroethane being formed in minor amounts.ALSO:A catalyst for the hydrofluorination of acetylenes comprises one or more mercury derivatives laid on a carrier formed of a porous sintered alumina with a total porosity of between 5 and 50 cm3/100g. of alumina and a specific surface area of between 0.01 and 1 m2/g. The alumina may have various forms, for example granules, fragments, balls and pellets. The catalysts may be prepared by impregnating sintered alumina with a solution of a mercury derivative and then drying the impregnated product. Before conducting the hydrofluorination reaction a gaseous current of anhydrous hydrogen fluoride, which may be diluted with a gas which is inert to the hydrogen fluoride and to the catalyst, may be passed through a bed of the catalyst at a temperature above 20 DEG C. Examples describe catalysts in which the mercury derivative is mercuric nitrate.