Chinese Journal of Catalysis ›› 2013, Vol. 34 ›› Issue (11): 2047-2056.DOI: 10.1016/S1872-2067(12)60681-0

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Catalytic conversion of methyl chloride to lower olefins over modified H-ZSM-34

Ting Xu, Hang Song, Weiping Deng, Qinghong Zhang, Ye Wang   

  1. State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
  • Received:2013-07-04 Revised:2013-08-16 Online:2013-10-18 Published:2013-10-18
  • Contact: Weiping Deng,Ye Wang
  • Supported by:

    This work was supported by the National Basic Research Program of China (2010CB732303), the National Natural Science Foundation of China (21173174, 20923004, 21033006, and 21161130522), and the Program for Changjiang Scholars and Innovative Research Team in University (IRT1036).

Abstract:

Among several typical zeolites, H-ZSM-34 was found to be an efficient catalyst for the conversion of methyl chloride to lower olefins, i.e., ethylene, propylene, and butenes. Treatment of H-ZSM-34 with a Na2H2EDTA (EDTA = ethylenediaminetetraacetate) aqueous solution followed by ion exchange and calcination enhanced the catalytic performance significantly. The selectivity to lower olefins increased significantly for certain Na2H2EDTA aqueous solution concentrations; when the H-ZSM-34 catalyst was treated with a 0.1 mol/L Na2H2EDTA solution, the selectivity and yield of C2-C4 olefins reached 82% and 61%, respectively, at 673 K and a CH3Cl partial pressure of 9.2 kPa. The modification of H-ZSM-34 with Ce ions improved C2-C4 olefin selectivity and yield. Catalyst characterization suggests that treatment with Na2H2EDTA or modification by Ce decreases the acidity of H-ZSM-34. The weakened acidity of the treated or modified H-ZSM-34 may suppress the hydrogen transfer reaction and prevent lower olefins from further transformation to paraffins.

Key words: Methyl chloride, Lower olefins, H-ZSM-34, Ethylenediaminetetraacetate treatment, Cerium modification, Acidity