Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (7): 1785-1794.doi: 10.3866/PKU.WHXB201604152

• ARTICLE • Previous Articles     Next Articles

Deactivation and Regeneration of HZSM-5 Zeolite in Methanol-to-Propylene Reaction

Si HU1,Qing ZHANG2,Yan-Jun GONG2,Ying ZHANG1,Zhi-Jie WU2,Tao DOU2,*()   

  1. 1 Department of Materials Science and Engineering, College of Science, China University of Petroleum-Beijing, Beijing 102249, P. R. China
    2 The Key Laboratory of Catalysis, China National Petroleum Corporation, China University of Petroleum-Beijing, Beijing 102249, P. R. China
  • Received:2016-01-20 Published:2016-07-08
  • Contact: Tao DOU E-mail:doutao@cup.edu.cn
  • Supported by:
    The project was supported by the National Key Basic Research Program of China(973);The project was supported by the National Key Basic Research Program of China(2012CB215002);National Natural Science Foundation of China(21206192);National Natural Science Foundation of China(21276278)

Abstract:

The cause of the deactivation of a methanol-to-propylene (MTP) catalyst after multiple reaction cycles was studied. On this basis, a facile and effective approach, i.e., secondary crystallization, was proposed and applied to the regeneration of the catalyst. The HZSM-5 zeolite catalysts before and after regeneration were characterized by a series of techniques, including powder X-ray diffraction (XRD), X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), N2 adsorption, 27Al magic-angle spinning nuclear magnetic resonance (27Al MAS NMR), temperature-programmed desorption of ammonia (NH3-TPD), and infrared spectroscopy of adsorbed pyridine (Py-IR). The physicochemical properties, such as framework, silica/alumina ratio, texture, and acidity, of the deactivated catalysts and the regenerated ones were investigated in detail. The catalytic performance of the zeolites in MTP conversion was tested under operating conditions of T=470 ℃, p=0.1 MPa (pMeOH=30 kPa) and weight hourly space velocity (WHSV)=1 h-1. The collapse of the zeolite structure and loss of active sites were found to be the essential reasons for the decline in catalyst activity after multiple reaction cycles. By regeneration via secondary crystallization, the relative crystallization, specific surface area, pore volume and acidity of the HZSM-5 catalyst were increased prominently. Meanwhile, the destroyed crystal structure and acid sites of the deactivated catalyst were restored effectively. Thus, the regenerated catalyst again exhibited excellent methanol conversion capacity and propylene selectivity in the MTP reaction.

Key words: Methanol, Propylene, ZSM-5 zeolite, Deactivation, Regeneration, Secondary crystallization

MSC2000: 

  • O643.3