Abstract :
Thermal characterization of Pd/TiO2-Al2O3 catalysts under oxygen or hydrogen atmosphere was investigated by means of thermogravimetry (TG), differential scanning calorimetry (DSC), temperature programmed reduction (TPR) and temperature programmed desorption (TPD). Further, the effects of titania on the catalytic property of Pd/Al2O3 towards methane combustion were also examined. A TG–DSC studies revealed that the heat evolved during oxygen adsorption at 25 °C depended on the crystallite diameter. TPR and TPD studies of oxidized samples also demonstrated that the coating of Pd/Al2O3 catalysts with titania can weaken the strength of the PdO bonds. Apparently the effect of coating Pd/Al2O3 catalyst with TiO2 is the improvement of the methane combustion at lower temperatures. This is probably due to the decrease of the strength of the PdO bonds.
