Highly disperse CeO2 nanoparticles on MgO hexagonal plates as oxidation catalyst

Abstract A low-loading lanthanide catalyst composed of highly disperse CeO2 nanoparticles supported on magnesium oxide hexagonal nanoplates (MgO-h) was synthesized. This catalyst showed enhanced reducibility and better catalytic performance (higher activity and full oxidation) for combustion reactions as compared to a conventional high surface area CeO2 powder. Structural characterization by transmission electron microscopy indicates that MgO-h exposes -preferably- (111) planes, allowing the anchoring of small and highly defective cerium oxide particles, with up to 18 % Ce3+. These particles activate molecular oxygen as peroxide (O2−2) and superoxide (O2-) species. CeO2/MgO-h catalyst presented a lower apparent activation energy than the bulk CeO2 (57 versus 90 kJ/mol, respectively) for CO oxidation. As well, high oxidation activity and selectivity to CO2 are observed for toluene oxidation, that is, while bulk CeO2 produces a significant amount of CO, CeO2/MgO-h is almost completely selective to CO2 (SCO2 > 91 %).