Oxidation of isobutene over selenium dioxide modified copper oxide catalysts.

Abstract

The effect of various amounts of SeO2, a p-type impurity, in modifying the selectivity of the copper oxide catalysts for methacrolein production, in the catalytic oxidation of isobutylene was investigated, at different feed ratios and several temperatures up to 425°C, in an isothermal integral flow reactor. The reaction products were analyzed quantitatively by gas chromatography. It has been found that there is an optimal amount of SeO2 required at each operating condition to enhance the selectivity of the catalyst. The experimental results are explained with the electron theory of catalysis on semiconductors and a reaction mechanism proposed. It has been postulated that the rate determining step in the partial oxidation of isobutene to methacrolein is a p-type and its further oxidation to water and CO2 is an n-type, under the operating, conditions.