摘要
Graphical Methane combustion : Defect-Rich CeO 2 −Al 2 O 3 supported palladium catalysts can prominently improve the dispersion of palladium species and strengthen the concentration of active surface oxygen species, resulting in excellent catalytic activity for methane combustion. In heterogeneous catalysis, the strong interaction between metal and support can significantly modulate the electronic properties of the metals and play a crucial role in metal particle dispersion and morphology. Herein, a facile strategy was utilized to fabricate highly dispersive palladium catalysts supported on defective Al 2 O 3 −CeO 2 for lean methane oxidation. Ceria was immobilized on the coordinatively unsaturated Al 3+ penta sites of γ-alumina activated by pre-reduction to fabricate hybrid-oxide support (abbreviated as RAl 2 O 3 −CeO 2 ), and then Pd precursor was uniformly deposited on the defective surface. Such a RAl 2 O 3 −CeO 2 interface can effectively upgrade the dispersion of deposited palladium species and improve the concentration of reactive oxygen species owing to strong electronic interactions, invoking a superior catalytic activity for lean methane oxidation. After loading 1.0 wt% palladium, Pd/RAl 2 O 3 −CeO 2 exhibited a 90 % methane conversion at 328 °C under the space velocity of 60,000 mL g −1 h −1 , far lower than that of bare 1.0 wt% Pd/RAl 2 O 3 (400 °C). In addition, Pd/RAl 2 O 3 −CeO 2 catalyst showed an excellent hydrothermal stability under the harsh conditions (600 °C, water vapor)for 120 h without obvious deactivation. The reaction pathway of total methane combustion was elucidated by in situ DRIFTS. The crucial intermediate compositions (carbon oxygenates and carbonate)on Pd/RAl 2 O 3 −CeO 2 surface are more readily oxidized into CO 2 and H 2 O. This work provides an effective interface-promoted strategy to develop efficient and durable palladium catalysts for many challenging reactions.
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