Influence of carrier effect on Pd/Al(2)O(3) for methane complete catalytic oxidation

Pd/Al(2)O(3) catalysts modified by different chemical elements (Mg, Si, Ce, and Zr) were tested for methane (CH(4)) catalytic combustion, and PdO nanoparticles loaded on modified Al(2)O(3) were systematically studied. These conditions assess the carrier effects of Pd/Al(2)O(3) and acid strength influences on CH(4) combustion. We observed carrier effects on activation energy through tuning Pd 3d binding energies (BEs) and on pre-exponential factors (A) through Pd dispersion and acidity on supports. When the BE of Pd 3d(5/2) is 337.3 eV, PdO nanoparticles loaded on modified Al(2)O(3) have excellent activity in cracking the C−H bond of CH(4), which leads to the lowest activation energy (E ( a )), regardless of the size effect of the PdO nanoparticle. Furthermore, a theoretical construction that acid sites on catalysts promote the reversible elementary step (2Pd−OH ↔ Pd−O* + Pd* + H(2)O) right shifts improving the A dependency on the quantity of exposed Pd* and Pd−O*. As a result, Al(2)O(3), as the carrier, not only modifies the electronic characteristics and size of supported PdO nanoparticles but also participates in the reaction process via acid sites on the surface of Al(2)O(3).