Oxidation of methyl ethyl ketone to diacetyl on V 2O 5-P 2O 5 catalysts

Abstract

A V 2O 5-P 2O 5 catalyst with a P V atomic ratio of 1.6 prepared by using oxalic acid as a reducing agent was found to be effective for the synthesis of diacetyl in the vapor-phase air-oxidation of methyl ethyl ketone (MEK). The selectivity to diacetyl was about 40 mol% at MEK conversions of up to 70%, and it decreased slightly with a further increase in the conversion. The selectivity for the oxidative CC fission to form acetic acid and acetaldehyde varied from 58 to 56 mol% with an increase in the conversion. The rate was nearly proportional both to the oxygen concentration up to 20 vol% and to the MEK concentration up to 10 vol%, even at the low temperature of 140 °C. The apparent activation energy was 7.6 kcal/mol. The addition of water vapor favors the oxidative fission against the diacetyl formation. The effects of reaction variables on the selectivity was also studied. A peroxide-like reaction mechanism was proposed.