Chemical Research in Chinese Universities ›› 2022, Vol. 38 ›› Issue (1): 229-236.doi: 10.1007/s40242-021-1391-0

• Articles • Previous Articles     Next Articles

Influence of the ZSM-5 Support Acidity on the Catalytic Performance of Pd/ZSM-5 in Lean Methane Oxidation

LUO Li1,2, WANG Sen1, WU Zhiwei1, QIN Zhangfeng1, DONG Mei1, WANG Jianguo1,2, FAN Weibin1   

  1. 1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China;
    2. University of the Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2021-09-27 Revised:2021-11-01 Online:2022-02-01 Published:2022-01-20
  • Contact: WANG Sen, QIN Zhangfeng, FAN Weibin E-mail:wangsen@sxicc.ac.cn;qzhf@sxicc.ac.cn;fanwb@sxicc.ac.cn
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (Nos.U2003123, U1862101, 21991092, 21972159, 21773281, 21802157), the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDA21020500), and CAS/SAFEA International Partnership Program for Creative Research Teams.

Abstract: Although zeolites are characterized by their special acidic properties, there is still no clear consensus on the effect of zeolite support acidity on the catalytic activity of supported Pd catalyst in methane oxidation. Herein, a series of Pd/H-ZSM-5 and Pd/Silicalite-1 catalysts was prepared by the deposition-precipitation method and used in lean methane oxidation. The effect of ZSM-5 support acidity on the catalytic performance of Pd/ZSM-5 was investigated. The results indicate that with the decrease of Si/Al ratio(x), viz., the increase of acid sites in H-ZSM-5(x), the catalytic activity of Pd/H-ZSM-5(x) increases substantially; the activity of various catalysts in the lean methane oxidation decreases in the order of Pd/H-ZSM-5(28)>Pd/H-ZSM-5(48)>Pd/H-ZSM-5(88)>Pd/H-ZSM-5(204)>Pd/Silicalite-1. Furthermore, various characterization measures reveal that the catalytic activity of Pd/H-ZSM-5(x) in lean methane oxidation is mainly related to the Lewis acid sites in the H-ZSM-5 support, whereas less relevant to the Brønsted acid sites. The abundant Lewis acid sites in H-ZSM-5 are capable to enhance the interaction between the Pd species and H-ZSM-5 support, which can inhibit the agglomeration of Pd particles and improve the dispersion of Pd species, and thus boost the catalytic activity of Pd/H-ZSM-5 in methane oxidation.

Key words: Lean methane, Catalytic oxidation, Pd/H-ZSM-5, Brønsted acid, Lewis acid, Pd dispersion