Promotion of Low-Temperature Oxidation of Propane through Introduction of Ce into Mullite Oxide YMn2 O5.

ABSTRACT

A high-surface-area Ce doped mullite YMn2 O5 was developed via a facile hydrothermal approach, which exhibited higher catalytic activity with a long thermal stability towards propane oxidation in regards to pristine mullite YMn2 O5 . T90 (the temperature at 90 % conversion of reactant) of propane over the mixed oxides is ∼40 °C lower than that over pristine YMn2 O5 mullite (147 m2 /g). The complete oxidation temperature occurs at as low as 225 °C (1000 ppm C3 H8 and 10 % O2 balanced with N2 , WHSV=30,000 mL/g h). Notably, the mixed oxides maintain superior catalytic stability at 250 °C for 120 h without noticeable loss in the activity. Fundamentally, the remarkable performance stems from the abundant oxygen defects caused by the lattice mismatch between CeO2 and YMn2 O5 , which is conducive to the gas phase oxygen adsorption and activation, thereby enhancing the low temperature catalytic activity of the material. In addition, the CeO2 on the catalyst's surface acts as an oxygen reservoir and provides additional adsorption sites for propane to promote the oxidation reaction. In situ DRIFTS results indicates that the dissociation of acrylate could be the key step for propane oxidation since acrylate is more difficult to decompose and desorb than formate and acetate. These findings revealed the roles of ceria on mullite oxides for propane oxidation activity.