Formation of Glyoxal by Oxidative Dehydrogenation of Ethylene Glycol

Abstract Iron(III) phosphates doped with a very small amount of molybdenum(VI) were found to be effective as catalysts for a vapor-phase oxidative dehydrogenation of ethylene glycol to glyoxal. The effects of the molybdenum(VI) content and of the reaction variables on the conversion of ethylene glycol and selectivity to glyoxal were studied. The optimum Mo/Fe atomic ratio was in the range from 0.002 to 0.01. The highest selectivity to glyoxal was obtained in the temperature range of 290 to 310 °C. The rate of ethylene glycol consumption increased almost in proportion to the oxygen concentration, while the selectivity to glyoxal increased only slightly as the oxygen concentration was increased. The selectivity to glyoxal increased markedly as the concentration of water was increased. It reached 37 and 32 mol% at ethylene glycol conversions of 60 and 80%, respectively. The one-pass yield of glyoxal reached 26.5 mol%.