1. Graduate University of Chinese Academy of Sciences, Beijing 100049, China; 2. State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
A series of SAPO-34 molecular sieves with different SiO2/Al2O3 ratios have been synthesized for the methanol-to-olefin (MTO) reaction. Their physico-chemical properties are characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption-desorption. The results are compared with those of the commercial HZSM-5, which show that the crystallinity and particle diameter of SAPO-34 as well as HZSM-5 increase with SiO2/Al2O3 ratio. The variation of BET surface area of SAPO-34 is different from that of HZSM-5 and the sample with SiO2/Al2O3 ratio of 0.4 exhibits the highest BET surface area. FT-IR spectra indicate that HZSM-5 has both Br?nsted and Lewis acid sites and Br?nsted acid sites are stronger, whereas SAPO-34 samples are dominated only by Lewis acid sites. When the SiO2/Al2O3 ratio increases, propylene and butylenes become the predominant product of the MTO reaction over HZSM-5. In contrast, the main products of this reaction catalyzed by SAPO-34 are ethylene and propylene. According to the product distribution, the reaction mechanism over HZSM-5 catalysts is proposed.
Corresponding Author(s):
LI Zengxi,Email:zxli@home.ipe.ac.cn; ZHANG Suojiang,Email:sjzhang@home.ipe.ac.cn
引用本文:
. Effect of SiO2/Al2O3 ratio on the conversion of methanol to olefins over molecular sieve catalysts[J]. Frontiers of Chemical Science and Engineering, 2011, 5(1): 79-88.
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