Highly and stably dispersed Pt catalysts supported over La1−xSrxAlO3−0.5x perovskite for oxidative methane activation and their structures

• High metal dispersion of Pt/La1−xSrxAlO3−0.5x in an oxidative atmosphere.
• The dispersion of supported Pt increased at higher oxidative-treatment temperature.
• Pt/La0.7Sr0.3AlO2.85 catalyst showed higher activity for oxidative methane reaction.
• A strong interaction between metal and lattice oxygen of perovskite inhibited migration.

Catalytic activity for oxidative methane conversion (partial oxidation of methane) over Pt catalyst supported on La1−xSrxAlO3−0.5x was investigated. Pt/La0.7Sr0.3AlO2.85 showed higher and more stable hydrogen yield than Pt/α-Al2O3 did. Pt/La0.7Sr0.3AlO2.85 showed higher catalytic activity for steam reform of methane even in an oxidative atmosphere, which was attributable to high Pt dispersion in the oxidative reaction atmosphere. Pt dispersion over La0.8Sr0.2AlO2.9 or La0.7Sr0.3AlO2.85 increased concomitantly with increasing calcination temperature in air. This phenomenon was not observed by aging in He flow. From structural analyses using XRD, XPS, EXAFS, and XANES, the interaction or coordination between Pt and surface oxygen (Os) was observed. This coordination was weakened in a reductive atmosphere and regenerated in an oxidative atmosphere. This interaction or coordination between the Pt and La1−xSrxAlO3−0.5x contributed to high Pt dispersion in an oxidative atmosphere and to high catalytic activity for the partial oxidation of methane.

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