Insight into the selective oxidation of isobutene to methacrolein over Ce-accelerated Mo-Bi-Fe-Co-K-O catalyst

Understanding the mechanism of multi-component metal oxide catalyst for the selective oxidation of isobutene to methacrolein has long been challenging for its complexity. Herein, the key role of Ce on the Mo-Bi-Fe-Co-K-O catalysts for accelerating the selectivity of methacrolein was revealed. It was suggested that the Ce addition could replace the Bi3+ and then generate defects which changed the transformation of electron and the migration mobility of ions: Ⅰ. the production of Ce3+/Ce4+ and Co2+/Co3+ redox couples regulated the catalytic redox ability; and Ⅱ. the interaction effect between Ce and Co enhanced the storage capacity and mobility of oxygen which could benefit the adsorption and activation ability for isobutene molecules. Interestingly, it was found that adding appropriate amount of Ce adjusted the molar ratio of the catalytically active lattice oxygen and defect oxygen species. Therefore, proper amount of Ce addition to the catalyst significantly accelerated the methacrolein selectivity from 47.9% to 70.6%.