Lean methane catalytic combustion using Pd/ZSM-5 catalysts prepared by ammonia evaporation method

Abstract

Catalytic combustion of lean methane is an effective measure to alleviate the greenhouse effect, which posing extensive demands for catalysts with appreciable reactivity and thermal stability. Herein, the reactivity and thermal stability of Pd/ZSM-5 catalysts prepared by ammonia evaporation and impregnation were tested. Experimental results indicated that the catalyst prepared by the ammonia evaporation method exhibited higher catalytic activity than that prepared by the impregnation method with similar Pd loadings. Especially, when the palladium loading is 0.1 %, the methane conversion of Pd/ZSM-5 prepared by AE method maintained at 80 % for 12 h at 550 °C while the methane conversion of Pd/ZSM-5 prepared by IM method decreased from 70 % to 20 % within 12 h at 550 °C. Through characterization, it was found that the elevated reactivity originated from the high dispersion of palladium due to the boosted interaction between palladium species and ZSM-5 support. These findings on the preparation of Pd catalysts via ammonia evaporation offer a practical reference for catalyst preparation environment adjustment, active species anchoring, and support-metal interactions, thus providing a promising blueprint for the design of future methane catalytic combustion materials.