64 High-Pressure Synthesis of Glycolic Acid from Formaldehyde, Carbon Monoxide, and Water in Presence of Nickel, Cobalt, and Iron Catalysts

Abstract

The synthesis of glycolic acid from formaldehyde, carbon monoxide, and water has been carried out, using nickel, cobalt, and iron catalysts at 150-275° and pressures of 150-600 atm. The reduced metals are practically inactive, whereas their halides show catalytic activity in the order Ni > Co > Fe and I > Br > Cl. As a catalyst support, silica gel is superior to kieselguhr, pumice, kaolin, and charcoal. Incorporation of cuprous iodide, thoria, and magnesia, singly or in mixture, and of excess iodine adversely affects the catalytic activity. The effect of operating temperature, pressure, carbon monoxide purity, residence period, concentration, and volume of catalyst and of formaldehyde solution, etc., has been studied and optimum conditions determined. Using 88.9% nickel iodide on silica gel as a catalyst at 200° and 8,700 p. s. i. maximum pressure, a total process conversion of 47.0%, of formaldehyde to liquid products has been obtained in a period of three hours, of which glycolic acid corresponds to 42.5%, formic acid 2.2%, and methyl alcohol 2.3%. With cobalt and iron catalysts, the yields are smaller.