Electron transferring with oxygen defects on Ni-promoted Pd/Al2O3 catalysts for low-temperature lean methane combustion
Jieying Cai, Jingyi Wang, Congwei Liu, Yan Zhang, Yun Liu, Peng Wang, Xuehai Wang, Xiangchen Fang, Yunbo Yu, Wenpo Shan
Abstract
Methane (CH 4 ) is the second most consequential greenhouse gas after CO 2 , with a substantial global warming potential. The CH 4 catalytic combustion offers an efficient method for the elimination of CH 4 . However, improving the catalytic performance of Pd-based materials for low-temperature CH 4 combustion remains a big challenge. In this study, we synthesized an enhanced Pd/5NiAlO x catalyst that demonstrated superior catalytic activity and improved water resistance compared to the Pd/Al 2 O 3 catalyst. Specifically, the T 90 was decreased by over 100 °C under both dry and wet conditions. Introducing Ni resulted in an enormously enhanced number of oxygen defects on the obtained 5NiAlO x support. This defect-rich support facilitates the anchoring of PdO through increased electron transfer , thereby inhibiting the production of high-valence Pd (2+δ)+ and stimulating the generation of unsaturated Pd sites. Pd 0 can effectively activate surface oxygen and PdO plays a significant role in activating CH 4 , resulting in high activity for Pd/5NiAlO x . On the other hand, the increased water resistance of Pd/5NiAlO x was mainly due to the generation of *OOH species and the lower accumulation of surface -OH species during the reaction process.