Journal of East China Normal University(Natural Science) ›› 2023, Vol. 2023 ›› Issue (1): 95-103.doi: 10.3969/j.issn.1000-5641.2023.01.010

• Catalytic Reaction Technologies • Previous Articles     Next Articles

Study of an Na2WO4/Mn7SiO12-SiO2 oxygen-carrier catalyst for chemical looping-oxidative coupling of methane

Ya GAO1, Weidong SUN1, Guofeng ZHAO1, Ye LIU1, Yong LU1,2,*()   

  1. 1. Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China
    2. Institute of Eco-Chongming, Shanghai 202162, China
  • Received:2022-06-15 Accepted:2022-09-21 Online:2023-01-25 Published:2023-01-07
  • Contact: Yong LU


A promising chemical looping-oxidative coupling of methane (CL-OCM) oxygen-carrier catalyst, Na2WO4/Mn7SiO12-SiO2, was obtained by adding extra Mn2O3 to Mn2O3-Na2WO4/SiO2 and in-situ activating in the reaction stream. After experiencing an induction period, the oxygen-carrier phase transformed from Mn2O3 to Mn7SiO12 in association with an improvement in C2-C3 selectivity but decreased CH4 conversion. The Na2WO4/Mn7SiO12-SiO2 oxygen-carrier catalysts could also be obtained by directly calcining the Na2WO4/Mn2O3-SiO2 precursor at 800 ℃ in air. At 750 ℃ and a CH4 residence time of 12 s, the catalyst achieved 12% (or 7%) CH4 conversion and 81.5% (or 90.0%) C2-C3 selectivity using a mCat/mCH4 weight ratio of 27 (or 13.5). Notably, only C3H6 was detected as C3 products, whose selectivity was about 5%. The CL-OCM reaction proceeded selectively through the redox cycle mode of Mn7SiO12 $ \leftrightarrow $ [MnSiO3 + MnWO4]. The lattice-oxygen mobility in Mn7SiO12 was much weaker than that in Mn2O3, which improved C2-C3 selectivity but decreased CH4 conversion. Our findings provide guidance for the exploration of more advanced catalytic oxygen-carrier catalysts toward efficient CL-OCM process.

Key words: oxidative coupling of methane to ethylene, chemical looping, oxygen-carrier catalyst, lattice-oxygen oxidation, manganese

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