MCM-22分子筛催化剂催化液化气中丁烯的芳构化

Aromatization of Butene in Liquefied Petroleum Gas over MCM-22 Molecular Sieve Catalyst

在连续流动的固定床反应装置上,研究了不同硅铝比的MCM-22分子筛催化剂用于液化气中丁烯芳构化反应的催化性能。采用X射线衍射、X射线荧光光谱、低温N_2吸附-脱附及氨程序升温脱附等方法研究了MCM-22分子筛的结构及MCM-22分子筛催化剂的孔结构性质和酸性。实验结果表明,配料硅铝比(n(SiO_2):n(Al_2O_3))为30～600的MCM-22分子筛的晶化度均较高,由其制备的催化剂初始丁烯转化率均达97%以上,但催化剂的芳构化活性随反应时间的延长而降低;配料硅铝比为50～200的MCM-22分子筛催化剂表现出较高的反应稳定性;MCM-22分子筛催化剂的失活主要源于酸中心数量的减少和微孔孔道堵塞,并且两者的影响程度与MCM-22分子筛的硅铝比相关。

Aromatization of butene in liquefied petroleum gas on MCM-22 molecular sieve catalysts with different silica to alumina ratios（ n（ SiO2 ）： n（ Al2O3 ） ） were carried out in a continuous fixed bed reactor. The structural characteristics, pore structure and acidity distribution of MCM-22 molecular sieves catalysts were investigated by means of XRD, XRF, N2 adsorption-desorption at low temperature（77.4 K） and NH3-TPD. All MCM-22 molecular sieves with n（ SiO2）： n（ Al2O3 ） from 30 to 600 are high in crystallinity. The initial butene conversion is more than 97% on all MCM-22 molecular sieves catalysts with different n （SiO2 ）： n （Al2O3 ）, but their aromatization activities decrease with reaction time on stream. Appreciable aromatization stability can be achieved on MCM-22 molecular sieve catalysts with proper n（ SiO2 ） ： n（ Al2O3 ） of 50 - 200. The main reasons of catalyst deactivation are decrease of acid sites and/or blockage of pore channels, which strongly depend upon n（SiO2） ： n（Al2O3） of MCM-22 molecular sieves.