Acta Chimica Sinica ›› 2004, Vol. 62 ›› Issue (18): 1706-1712. Previous Articles     Next Articles

甲烷无氧脱氢芳构化双促进W/MCM-22基催化剂研究

黄利强, 曾金龙, 林国栋, 袁友珠, 张鸿斌   

  1. 厦门大学化学化工学院, 固体表面物理化学国家重点实验室, 厦门, 361005
  • 投稿日期:2004-04-07 修回日期:2004-08-12 发布日期:2014-02-17
  • 通讯作者: 张鸿斌,E-mail:hbzhang@xmu.edu.cn. E-mail:hbzhang@xmu.edu.cn.
  • 基金资助:
    国家重点基础研究规划"天然气、煤层气优化利用的催化基础"(No.G1999022400)资助项目.

Study on Doubly Promoted W/MCM-22-based Catalysts for Dehydro-aromatization of CH4 in the Absence of O2

HUANG Li-Qiang, ZENG Jin-Long, LIN Guo-Dong, YUAN You-Zhu, ZHANG Hong-Bin   

  1. Institute of Chemistry & Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surface, Xiamen University, Xiamen 361005
  • Received:2004-04-07 Revised:2004-08-12 Published:2014-02-17

With incorporation of Ga3+/Zn2+ (or Co3+/2+/Mon+) into a W/MCM-22 host catalyst, highly active and heat-resistant doubly promoted W/MCM-22-based catalysts for dehydro-aromatization of methane (abbreviated as DHAM) were prepared. Over an 8% W-0.1% Co-0.4% Mo/MCM-22 or 8% W-0.1% Ga-0.6% Zn/MCM-22 catalyst, 70%~72% selectivity to benzene formation at ~15% conversion of CH4 could be achieved in the initial ~3 h of reaction under reaction condition of 0.1 MPa, 1073 K, GHSV=1500 mL(STP)·h-1·(g-cat.)-1. Addition of a proper amount of CO2(≤1.2%) or H2(~7.0%) to the feed-gas was found to significantly enhance conversion of CH4 and selectivity to benzene, and to improve the performance of coke-resistance of the catalysts. By correlating the results of the NH3-TPD measurements and the catalyst tests, it was confirmed that intensity and concentration of the surface B-acid sites have pronounced effects on the performance of the catalyst for DHAM reaction. It was found experimentally that addition of a proper amount of Ga3+/Zn2+ (or Co3+/2+/Mon+) into W/MCM-22 host catalyst resulted not only in eliminating parts of the strong surface B-acid sites but also in generating a kind of new medium-strong acid sites, mostly B-acid sites, simultaneously. The latter could serve as the catalytically active sites for DHAM reaction, and on such medium-strong surface B-acid sites, the formation of coke would be also alleviated to a greater extent. On the other hand, the doping of the Ga3+/Zn2+ (or Co3+/2+/Mon+)-components to tungsten oxide matrix would facilitate inhibiting aggregation of the W-containing active species and improving dispersion of the W-component at the surface of catalyst, thus leading to a pronounced decrease in the reduction-temperature for the hard-to-be-reduced W6+-species and an increase in quantity of the reducible W6+-species, as evidenced by the results of the H2-TPR study. The above two roles that Ga3+/Zn2+ (or Co3+/2+/Mon+) as promoters played were contributed to the high CH4 conversion and benzene selectivity, the alleviation of coke deposition and the improvement of the durability of the catalyst.

Key words: methane, dehydro-aromatization, W/MCM222,W-Zn-Ga/MCM-22, W-Mo-Co/MCM-22