Interface Engineering of Hierarchically Confined Pt-MnO 2 /m-Al 2 O 3 Catalysts and Their Performance and Mechanism in Low-Temperature Methane Catalytic Combustion
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In this study, hierarchically confined Pt-MnO 2 /m- Al 2 O 3 catalysts were synthesized via a precipitation method using MnO 2 - Al 2 O 3 as promoters, and their methane catalytic combustion performance and structure-activity relationships were systematically investigated. The results demonstrate that the 0.5 wt% Pt-loaded Pt-MnO 2 /m- Al 2 O 3 catalyst achieved 90% methane conversion at 228 ℃ (T 90 ). The enhanced performance is attributed to three synergistic mechanisms: (1) Pt doping induced lattice contraction in MnO 2 (XRD revealed a 0.03 Å reduction in the (001) interplanar spacing), which facilitated the formation of 3+ -oxygen vacancy pairs (XPS indicated a Mn 3+ - content of 79.87%); (2) The PtO-MnPt 3 O 6 interfacial structure (HAADF-STEM confirmed lattice spacings of 0.23/0.21 nm) accelerated oxygen species cycling, with lattice oxygen desorption capacity (O 2 -TPD) increasing by 38% compared to undoped samples; (3) The mesoporous m-Al 2 O 3 carrier provided effective confinement, achieving a high specific surface area (28.1 m 2 /g) and sub-nanometer Pt dispersion (particle size < 2 nm). Under conditions of 1000 ppm CH 4 and a space velocity of 30,000 h –1 , the catalyst maintained a methane conversion rate of 98.2 ± 0.5% during continuous operation for 30 hours. Post-cycling characterization revealed stable crystalline structure (XRD full width at half maximum of 0.35°±0.02°) and grain size (12.3 ± 0.5 nm), confirming its robustness for industrial applications. This study provides theoretical and experimental foundations for the rational design of highly efficient catalysts for low-concentration methane elimination.
