▎ 摘　　要

Birnessite-type MnO2 (delta-MnO2)-supported reduced graphene oxide (rGO)-promoted palladium (xPd-yrGO/delta-MnO2) samples were prepared using a polyvinyl alcohol-protected reduction method. The physicochemical properties of the catalysts were determined by means of numerous techniques, and their catalytic activities for the oxidation of toluene were evaluated. It was found that the introduction of rGO as an electron transfer bridge could significantly strengthen the metal-support interaction (SMSI) between Pd and delta-MnO2, thereby enhancing the catalytic activity of the sample. Among all of the xPd-yrGO/delta-MnO2 samples, 0.48Pd-1.0rGO/delta-MnO2 performed the best: the toluene oxidation rates were 3.41 x 10(-4) and 6.13 x 10(-4) mol g(-1) s(-1) at 177 and 189 degrees C, respectively, with a space velocity of 60 000 mL g(-1) h(-1), which were much higher than that of 0.45Pd/delta-MnO2 at similar temperatures. The doping of rGO led to an increase in the Mn3+/Mn4+ or O-ads/O-latt molar ratio, thus enhancing the catalytic activity of Pd/delta-MnO2. The good performance of 0.48Pd-1.0rGO/delta-MnO2 was associated with its high O-ads/O-latt molar ratio, good low-temperature reducibility, and strong interaction between Pd and delta-MnO2. In situ DRIFTS results revealed that benzaldehyde and benzoate were the intermediate products of toluene oxidation over 0.48Pd-1.0rGO/delta-MnO2. The physicochemical properties of the 0.48Pd-1.0rGO/delta-MnO2 sample were not changed significantly after 70 h of stability test, but the activity of this catalyst decreased in the presence of CO2, SO2 or NH3, which was due to the carbonate, sulfate and ammonia species formed on the surface of 0.48Pd-1.0rGO/delta-MnO2 that covered the active sites and oxygen vacancies and thereby reduced the ability to bind with toluene.