LAUSR

Abstract A series of Na-ZSM-5 zeolite supported Pd catalysts with different Si/Al ratios (Si/Al = 20, 40 and 80) were synthesized. And the effect of different Si/Al ratios on the catalytic combustion of VAM (with methane concentration below 1%) was investigated. The Pd/Na-ZSM-5-40 shows the best catalytic activity for VAM as to catalytic test. Through various techniques (XRD, SEM, HRTEM, XPS, H2-TPR and NH3-TPD), it is found that the advantage physicochemical properties of Pd/Na-ZSM-5-40 compared with Pd/Na-ZSM-5-20 and Pd/Na-ZSM-5-80: good dispersion and relatively small particle size of Pd particles, higher PdO and surface oxygen content, strong interaction between the active Pd species and the Na-ZSM-5 supports and more surface acid sites are all beneficial to methane oxidation. Furthermore, the CH4 conversion of Pd/Na-ZSM-5-40 at different GHSV (16000–112500 mL g−1 h−1) were remained after running for 50 h, suggesting a good stability.