Sintering inhibition of flame-made Pd/CeO2 nanocatalyst for low-temperature methane combustion
Dispersed palladium on the high-surface-area ceria support is synthesized via one-step flame-assisted spray pyrolysis method, which applies a highly-quenched stagnation-point flame controlling catalyst sizes and structures. The X-ray photoelectron spectroscopy (XPS) spectra of Pd show a significantly high binding energy for flame-made Pd/CeO 2 catalysts, possessing a value of 1.7 eV larger than the reference value in literature. It suggests that the partial electron transfer occurs from metal Pd to their supports during the synthesis process, which creates Pd electron-deficient (cationic Pd δ+ ) and Ce electron-rich (anion Ce δ − ), respectively. The catalytic activities of CH 4 oxidation are performed over the temperatures ranging from 200 °C to 600 °C. In comparison with inert support materials, the synergistic effect is found between palladium and support ceria that leads to the enhanced catalytic activity. During the heating and cooling cycles of CH 4 oxidation, Pd/CeO 2 catalysts exhibit an exceptional inhibition effect against the sintering of Pd cluster and its dispersion decrement, which is related to strong electronic interaction of metal-support interfaces induced by the aforementioned partial electron transfer.
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