GB575380A - Improvements in and relating to the production of ethylene glycol - Google Patents

Abstract

Ethylene glycol is produced by the catalytic hydrogenation of a glycollic acid ester in the vapour phase under superatmospheric pressure. The temperature and pressure are preferably so chosen that products do not condense on the catalyst. Pressures of 10-1000 atmospheres are mentioned. Suitable catalysts are copper, zinc oxide, catalysts suitable for methanol synthesis from carbon monoxide and hydrogen, and composition comprising copper, tin, silver, cadmium, zinc, lead or an oxide or chromite of one of these metals together with an oxide or chromite of barium, manganese or magnesium. They may be prepared by precipitation or fusion; for instance sulphur-free copper oxide and magnesia may be fused together in an electric furnace at 1000-1200 DEG C., and instead of magnesia there may be used an oxide of an alkaline earth, nickel, iron, cobalt, silicon, manganese, chromium, zinc, cadmium or silver; the catalyst is reduced in hydrogen before use. A carrier may be employed. Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, octyl, decyl and like glycollates of branched-chain alcohols produced with methanol in the carbon monoxide-hydrogen synthesis and glycol, glycerol, and phenyl glycollates are specified as starting materials. In examples, the initial esters are methyl, ethyl, butyl and isobutyl glycollates and the catalysts are prepared as follows: (1) by fusing cupric oxide and silica; (2) by precipitation with ammonia of a solution containing copper and zinc nitrates and ammonium chromate; (4) precipitating carbonates from a solution of zinc ammonium chromate and copper nitrate; (5) precipitating with ammonia a solution of copper nitrate and ammonium dichromate; in each case the precipitate is reduced in hydrogen. The space velocities are stated. Specification 385,625 is referred to.