Chinese Journal of Catalysis ›› 2018, Vol. 39 ›› Issue (8): 1395-1402.DOI: 10.1016/S1872-2067(18)63076-1

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Oxidative coupling of methane: MOx-modified (M=Ti, Mg, Ga, Zr) Mn2O3-Na2WO4/SiO2 catalysts and effect of MOx modification

Pengwei Wang, Xin Zhang, Guofeng Zhao, Ye Liu, Yong Lu   

  1. Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China
  • Received:2018-02-22 Revised:2018-03-31 Online:2018-08-18 Published:2018-07-04
  • Contact: 10.1016/S1872-2067(18)63076-1
  • Supported by:

    This work was supported by the Basic Key Project (18JC1412100) from the Shanghai Municipal Science and Technology Commission, the National Natural Science Foundation of China (21773069, 21703069, 21473057, U1462129), and the National Basic Research Program of China (973 program, 2011CB201403) from the MOST of China.

Abstract:

Mn2O3-Na2WO4/SiO2 is considered as the most promising catalyst for the oxidative coupling of methane (OCM) process; however, it only has a better catalytic performance over 800℃. To improve its low-temperature performance, an attempt has been made to modify the Mn2O3-Na2WO4/SiO2 catalyst using TiO2, MgO, Ga2O3, and ZrO2. Among the synthesized catalysts, the TiO2-modified Mn2O3-Na2WO4/SiO2 catalyst shows markedly improved low-temperature OCM performance, achieving a high CH4 conversion of ~23% and a good C2-C3 selectivity of ~73% at 700℃ (the catalyst bed temperature), along with promising stability for at least 300 h without signs of deactivation. In comparison with the unmodified Mn2O3-Na2WO4/SiO2 catalyst, the TiO2 modification results in significant improvement in the low-temperature activity/selectivity, whereas the MgO modification has almost no impact and the Ga2O3 and ZrO2 modifications have a negative effect. The X-ray diffraction (XRD) and Raman results reveal that the formation of a MnTiO3 phase and a MnTiO3-dominated catalyst surface is crucial for the improvement of the low-temperature activity/selectivity in the OCM process.

Key words: Oxidative coupling of methane, Light olefins, Ethylene, Oxide modification, MnTiO3