Au/Rod-like MnO2 catalyst via thermal decomposition of manganite precursor for the catalytic oxidation of toluene

Au/Rod-like MnO2 catalyst was prepared via thermal decomposition of Au/MnOOH precursor. Au nanoparticles (NPs) with an average size of about 3.05 nm were highly dispersed on the MnOOH supports. Au/MnO2-300 catalyst exhibited the best catalytic activity for toluene oxidation due to the abundant surface Mn4+ species, large specific surface area, good low-temperature reducibility and high oxygen species mobility. The further increase of thermal decomposition temperature resulted in the severe sintering of Au NPs, causing the decrease of toluene catalytic activity. The T-50 and T-90 values for Au/MnO2-300, 400 and 500 catalysts were 202, 207, 210 degrees C and 205, 210, 215 degrees C, respectively. The apparent activation energy of Au/MnO2-300 catalyst (61 kJ/mol) was obviously lower than those of Au/MnO2-400 (107.8 kJ/mol) and 500 (141.5 kJ/mol) catalysts. The reaction rates at 185 degrees C had a decrease tendency from 0.37 to 0.16 mol s(-1) g(cat)(-1) with the growth of Au NPs for Au/MnO2-300, 400 and 500 catalysts.