Oxidation of Ketones over Metal Oxide Catalysts. II. Biacetal Synthesis over Co3O4-Lanthanoid Oxide Catalysts

Article abstract of DOI:10.1246/bcsj.60.2757

The effects of the addition (10 atomicpercent) of lanthanoid oxides into Co3O4 on the oxidation of methyl ethyl ketone (MEK) were studied.The addition of La2O3 brought about marked enhancement of the rate of biacetyl (BA) formation.MEK conversion increased by a factor of 2.8 and the BA selectivity was improved at 450-500 K owing to the suppression of deep oxidation.The addition of CeO2 much improved the MEK conversion but BA selectivity decreased to less than 50percent and the scission reaction leading to acetaldehyde and acetic acid was enhanced.The addition of Pr6O11 improved MEK conversion but the addition of Nd2O3, Gd2O3, or Er2O3 showed little effect on MEK conversion.The reduction of both scission reaction and deep oxidation and the compensative increase in BA selectivities were observed.An approximately linear relationship was found between the specific rate of BA formation of the catalysts and logarithmic solubility product constants of hydroxydes of tervalent lanthanoid elements added, suggesting that the basicity of the catalysts is one of major factors for BA formation.The maximum efficiency (23.4percent) of BA formation was attained at a La content of ca. 10 at.percent.