Abstract:

The synthesis gas is carbonylated with dimethyl ether (DME) to synthesize methyl acetate (MA). The further hydrogenation of MA to produce ethanol is a new and efficient route for the production of ethanol from coal-based synthesis gas. Modification of HMOR zeolite using mild post-treatment method to improve its catalytic efficiency of DME carbonylation is considered as an efficient strategy for the industrialization application. In this study, tetraethylammonium hydroxide (TEAOH) was used to modify HMOR zeolite. The effects of organic base modification on the structure and catalytic performance of DME carbonylation of HMOR zeolite were firstly discussed. It was found that when the concentration of TEAOH was 0.3 mol/L, the mesopore volume and external specific surface area of the HMOR zeolite are increased about 26% and 10%, respectively, and the conversion rate of DME is increased by 68%. The OH^- generated by the hydrolysis of TEAOH can gently remove the skeleton silicon in the HMOR zeolite and the hierarchical pore structure can be successfully obtained. The generated hierarchical pore structure is favorable to the mass transfer rate in the carbonylation reaction process of DME. In addition, the hydrolyzed TEA⁺ is enriched on the surface of HMOR zeolite, which inhibits the excessive desilication of OH^- and protects the basic skeleton structure of HMOR zeolite from further destruction.

Key words: ethanol, dimethyl ether, carbonylation, methyl acetate, post-treatment of TEAOH, HMOR zeolite

摘要：

合成气经二甲醚（DME）羰基化合成乙酸甲酯（MA），MA进一步加氢制备乙醇是一种新型高效的煤基合成气制备乙醇路线。采用温和的后处理方法改性DME羰基化分子筛，进一步提高DME羰基化效率，对其工业应用具有重要意义。本研究利用四乙基氢氧化铵（TEAOH）对HMOR分子筛改性处理，探讨了有机碱改性处理对HMOR分子筛的结构和DME羰基化催化性能的影响。研究发现，TEAOH浓度为0.3 mol/L时，HMOR分子筛介孔孔容增大约26%，外比表面积增大约10%，DME的转化率增幅达68%。TEAOH水解产生的OH^-能够温和脱除HMOR分子筛中的骨架硅，获得介-微多级孔结构，提高DME羰基化反应过程中的传质速率。此外，水解的TEA⁺在分子筛表面富集，抑制了OH^-的过度脱硅，保护分子筛基本骨架结构不被更深层次破坏。

关键词: 乙醇, 二甲醚, 羰基化, 乙酸甲酯, 四乙基氢氧化铵后处理, HMOR分子筛