Novel Insights on the Metal–Support Interactions of Pd/ZrO<sub>2</sub> Catalysts on CH<sub>4</sub> Oxidation
Qi Li, Ya Wang, Wenzhe Si, Yue Peng, Junhua Li
Abstract
With the environmental harm of unburnt CH 4 in natural gas vehicle exhaust, oxidizing CH 4 to CO 2 over catalysts at low temperatures becomes an exigent issue. Supported Pd catalysts possess higher CH 4 activity than other noble metal catalysts. A series of Pd/ZrO 2 catalysts were synthesized to research the potential relationship among Pd particle morphology, electron transfer, CH 4 oxidation mechanism, and catalytic activity. Characterizations show that the ratio of PdO x facets to edge/corner sites on four catalysts increases in the order of PZ85 ≈ PZ40 < PZ55 < PZ70 because of the difference in content of surface −OH groups, and this order turns out to be the same as that of electron transfer intensity, revealing the degree of metal–support interactions. This kind of metal–support interaction in PZ70 can be helpful to accelerate CH 4 combustion via promoting the break of the C–H bond and dissociation of CO 3 * according to density functional theory studies. T 90 of the PZ70 catalyst with optimum catalytic activity reaches 331 °C.