Characterization and performance of SmxA1-xMnO3 (A=Ce, Sr, Ca) perovskite for efficient catalytic oxidation of toluene

Catalytic oxidation of toluene was implemented over SmMnO3, Sm(0.8)A(0.2)MnO(3) (ABO(3), A=Ce, Sr, Ca) and Sm(1-x)CaxMnO(3) (x=0.0, 0.1, 0.2, 0.3) perovskite oxides synthesized via sol-gel method. The effects of A-site substitution of SmMnO3 and the amount of calcium substitution of SmMnO3 perovskite-type catalyst on the catalytic activity of toluene were investigated in a fixed bed reactor. The structure and chemical properties of the perovskites were studied by XRD, SEM, XPS, and H-2-TPR. The results showed that the substitution of Ce and Ca had a positive impact about the catalytic properties of toluene oxidation, while a negative impact was caused by the substitution of Sr. The catalytic activity of toluene oxidation followed the order of Sm0.8Ca0.2MnO3>Sm0.8Ce0.2MnO3>SmMnO3>Sm0.8Sr0.2MnO3 in terms of the temperature of T-90%, at toluene concentration=1,000 ppm and weight hourly space velocity (WHSV)=3,000 mL/ g center dot h. Sm0.8Ca0.2MnO3 had the highest catalytic capacity (T-90%=238 degrees C), which could be attributed to its high adsorbed oxygen concentration, Mn4+/Mn3+, and the best low-temperature reducibility (H-2 consumption=0.36). Meanwhile, the Sm0.8Ca0.2MnO3 catalysts showed great long-term stability after 30 h of the reaction, and the toluene degradation rate remained over 95% at 350 degrees C.