CeO2-coated Pd core-shell catalyst supported by mesoporous γ-Al2O3 for methane oxidation: The effect of high temperature pretreatment on the active Pd species

Stabilizing Pd–cerium oxide–aluminum oxide catalysts for methane oxidation by reduction pretreatments

“…The increase in apparent average particle size of the Ce/Pd/Al-F catalyst is consistent with agglomeration and/or lower accessibility of the Pd active phase. 25 Both accessibility and nanoparticle size help explain the higher activity of the Pd/Ce/Al-F catalyst, despite the limited contact between Pd and Ce observed by STEM. The higher activity of the Pd/Ce/Al-F catalyst is consistent with the facilitated methane activation on smaller nanoparticles because of the structure sensitivity of σ bond activation.…”

“…Since aging at high temperature (>700 °C) could affect the activity and thermal stability due to deterioration of the support structure, reduced specific surface area, and/or sintering, 20,25,27,35 we tested the fresh and reduced Pd/Ce/Al and Ce/Pd/Al catalysts for methane oxidation after a treatment at 850 °C for 5 h under methane oxidation reaction conditions. In general, aging resulted in partial loss of catalytic activity for all catalysts (Fig.…”

“…[18][19][20][21][22][23][24] Even for state-of-the-art Pd catalysts, the deactivation at high temperatures due to sintering and or aggregation of metal active sites remains an issue. 7,23,25 To improve the thermal stability of Pd by a physical barrier, encapsulation 21,23,25 and atom trapping [26][27][28] with CeO 2 were targeted, using different approaches. Even though encapsulation is a good strategy, it needs advanced catalyst synthesis methods, which are not easily scalable.…”