催化学报

催化学报 ›› 2008, Vol. 29 ›› Issue (5): 447-452.

• 研究论文 • 上一篇    下一篇

MgO和CaO助剂在Fe-K催化剂中的作用

陈铜,范勤,廖仕杰,倪军平,缪长喜   

  1. 中国石油化工股份有限公司上海石油化工研究院, 上海 201208
  • 收稿日期:2008-05-25 出版日期:2008-05-25 发布日期:2012-05-02

Effects of MgO and CaO Promoters on Fe-K-Based Catalysts

CHEN Tong*, FAN Qin, LIAO Shijie, NI Junping, MIAO Changxi   

  1. Shanghai Research Institute of Petrochemical Technology, SINOPEC, Shanghai 201208, China
  • Received:2008-05-25 Online:2008-05-25 Published:2012-05-02

PDF

1085

被引次数

39

摘要： 制备了以MgO和CaO为助剂的乙苯脱氢制苯乙烯用Fe-K催化剂,并考察了助剂对催化剂催化性能的影响. 应用SEM、XRD、TPR和Mssbauer谱等手段表征了MgO和CaO对活性前驱体K2Fe22O34晶相形成及其表观体相结构的影响. 结果表明,引入MgO助剂,半径相近的Mg2+与Fe3+极易发生取代形成固溶体,使活性前驱体K2Fe22O34晶相的形成温度有所降低,同时给体相结构引入氧空位,从而有利于乙苯发生晶格氧转移机理的脱氢反应,使催化剂活性提高. 引入CaO助剂,提高了K2Fe22O34晶相的结晶度和苯乙烯选择性,但催化剂活性有所下降. CaO对Fe-K催化剂的还原有一定的阻碍作用,是催化剂的稳定性助剂.

关键词: 乙苯, 脱氢, 苯乙烯, 氧化镁, 氧化钙, 助剂, 三氧化二铁, 氧化钾, 复合氧化物

Abstract: Fe-K-based catalysts with MgO and CaO as promoters were prepared, and their catalytic performance for dehydrogenation of ethylbenzene to styrene was examined in a fixed-bed reactor. The effects of MgO and CaO on the catalysts were characterized by means of SEM, XRD, TPR, and Mssbauer spectroscopy. The catalyst activity was improved by the substitution of Mg2+for Fe3+, and the formation temperature of the active precursor, K2Fe22O34, could be decreased owing to the solid solution of magnesium ferrite on the Fe-K-Mg-based catalyst. The crystallization degree and the selectivity for styrene were improved on the Fe-K-Ca-based catalyst, which was due to the CaO in/on the sill-like crystallites of K2Fe22O34. Furthermore, the reduction of Fe3+was prevented, and the structural stability of the catalyst was enhanced by the CaO promoter.

Key words: ethylbenzene, dehydrogenation, styrene, magnesia, calcium oxide, promoter, ironic oxide, potassium oxide, composite oxide