Engineering of oxygen vacancy defect in CeO2 through Mn doping for toluene catalytic oxidation at low temperature

Catalytic oxidation is considered a highly effective method for the elimination of volatile organic compounds. Oxygen vacancy defect engineering in a catalyst is considered an effective approach for high-performance catalysts. Herein, a series of doped MnxCe1-xO2 catalysts (x = 0.05-0.2) with oxygen vacancy defects were synthesized by doping low-valent Mn in a CeO2 lattice. Different characterization techniques were utilized to inspect the effect of doping on oxygen vacancy defect generation. The characterization results revealed that the Mn0.15Ce0.85O2 catalyst has the maximum oxygen vacancy concentration, leading to increased active oxygen species and enhanced oxygen mobility. Thus, Mn0.15Ce0.85O2 catalyst showed an excellent toluene oxidation activity with 90% toluene conversion temperature (T90) of 197 °C at a weight hourly space velocity of 40,000 mL g-1 h-1 as compared to undoped CeO2 (T90 = 225 °C) and Ce based oxides in previous reports. In addition, the Mn0.15Ce0.85O2 catalyst displayed strong recyclability, water resistant ability and long-time stability. The in situ DRIFT results showed that the Mn0.15Ce0.85O2 catalyst has a robust oxidation capability as toluene is quickly adsorbed and actuated as compared to CeO2. Thus, the present work lays the foundation for designing a highly active catalyst for toluene elimination from the environment.