干凝胶蒸汽辅助晶化构筑包覆结构ZSM-5及其甲醇制芳烃性能  

Construction of Coated ZSM-5 by Dry Gel Steam-Assisted Method and Its Performance for Methanol to Aromatic Reaction

作　　者：付廷俊[1] 马倩 惠燕 李忠[1] FU Tingjun;MA Qian;HUI Yan;LI Zhong(Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学省部共建煤基能源清洁高效利用国家重点实验室,太原030024

出　　处：《太原理工大学学报》2023年第3期410-417,共8页Journal of Taiyuan University of Technology

基　　金：国家自然科学基金资助项目(21978191,21878207);国家重点研发计划资助(2018YFB0604901)。

摘　　要：煤基甲醇经催化转化制苯、甲苯和二甲苯是煤炭高效清洁转化的重要技术。由于其反应步骤复杂,单一结构催化剂上难以调控反应过程,实现高的芳烃选择性。采用干凝胶蒸汽辅助晶化方法将硅铝比(Si/Al)约为50的ZSM-5原粉放入硅铝比为220的干凝胶中进行晶化制备包覆结构ZSM-5,以催化耦合甲醇制烯烃和烯烃芳构化两步反应,提升芳烃选择性。考察不同硅包覆比对甲醇制芳烃性能的影响发现,硅包覆比小于0.5时,凝胶中硅铝物种可于原粉表面成功包覆。外部的高硅铝比包覆结构促进了甲醇到低碳烯烃的转化,进而强化了甲醇分步芳构化过程,总芳烃选择性可从原粉的12.9%增加至14.5%,轻质芳烃在芳烃中的选择性也由原粉的61.8%增加至66.5%.当硅包覆比继续增加到2,部分硅铝物种在原粉外围独立成核形成小晶粒ZSM-5.虽然芳烃选择性增加到15.2%,但小晶粒也促进了芳烃的烷基化,使C9+芳烃选择性增加,抑制了轻质芳烃的形成。The conversion of coal-based methanol to benzene,toluene,and xylene is an important technology to promote the efficient and clean conversion of coal.However,the control of reaction process on a single catalyst is difficult and the aromatic selectivity is low.Coated ZSM-5 was prepared by steam-assisted crystallization,in which ZSM-5 with a Si/Al ratio of about 50 was mixed into dry gel with a Si/Al ratio of 220.Under the catalysis of the coated ZSM-5,the two-step reaction of methanol to olefin and olefin aromatization was performed to improve the aromatic selectivity.The effect of coating ratio on the catalytic performance of the prepared ZSM-5 was investigated.The results show that when the coating ratio was less than 0.5,the silicon and aluminum species in the gel could be coated on the surface of parent ZSM-5.The coating structure with high Si/Al ratio promoted the conversion of methanol to light olefin,and further enhanced the stepwise aromatization process of methanol.The aromatic selectivity increased from 12.9%of the original powder to 14.5%and the selectivity of light aromatic in total aromatic products also increased from 61.8%to 66.5%.When the coating ratio increased to 2,some silicon and aluminum species nucleated independently outside the original powder to form small crystal.Although the total aromatic selectivity increased to 15.2%,the small crystal promoted the alkylation of light aromatic to form heavy aromatic hydrocarbons,while the light aromatic selectivity decreased.

关 键 词：甲醇 芳烃 干凝胶蒸汽辅助转化 包覆型ZSM-5 芳烃选择性 

分 类 号：O643.3[理学—物理化学] TQ426[理学—化学]