Manufacture of pyruvic acid esters

摘要

A catalyst for the oxidation of lactic esters to pyruvic esters (see Group IV(b)) comprises iron oxide and molybdenum oxide supported on sintered alumina. The catalyst may be prepared by a series of impregnations of the sintered alumina with a solution containing iron and molybdenum salts (e.g. ferric ammonium oxalate tetrahydrate and ammonium molybdate tetrahydrate) and drying first at 125 DEG -130 DEG C. and then at 250 DEG -260 DEG C. after each impregnation. After use, the catalyst may be regenerated by heating at 350 DEG -400 DEG C. in the presence of oxygen generally as air. U.S.A. Specification 2,849,493 is referred to.ALSO:Pyruvic esters are obtained by the vapourphase oxidation of a lactic ester in the presence of an oxygen-containing gas and an iron oxide-molybdenum oxide catalyst supported on sintered alumina (see Group III) at 180-300 DEG C. The oxygen-containing gas may be air and which may be diluted with an equal volume of nitrogen or other inert gas. Specified esters which may be prepared are alkyl, aryl and aralkyl esters.