十元环分子筛在甲醇芳构化反应中催化性能的研究

合成了ZSM-5、ZSM-22、EU-1、MCM-22和ITQ-13具有十元环孔道结构的5种分子筛,研究了分子筛结构、酸性分布等因素对其在甲醇芳构化反应中催化性能的影响。研究表明,不同结构分子筛的形貌、酸性及孔径均存在较大差异,进而影响了其在甲醇制芳烃反应中的催化活性和稳定性。研究的5种分子筛中,ZSM-5表现出最佳的芳构化活性,芳烃收率达34.8%,MCM-22芳烃收率约为21.9%,而其他3种结构的分子筛催化剂基本未表现出甲醇芳构化活性。通过添加具有芳构化性能的Ga物种对ZSM-5和MCM-22进行改性,可显著提升芳烃收率,Ga/ZSM-5上芳烃收率达到40.8%,Ga/MCM-22上芳烃收率可提高到27.1%。另外,采用TG/DTA、GC等方法研究了失活催化剂的积炭情况,发现分子筛结构对积炭量、积炭组成及积炭分布存在显著影响。

An investigation on the catalytic performance of 10 MR zeolites in methanol aromatization reaction

Five zeolites ZSM-5, ZSM-22, EU-1, MCM-22, and ITQ-13 with 10 member ring channels were hydrothermally synthesized and their structure, acidity, morphology and catalytic behaviors in methanol aromatization reaction were compared. The results indicate that the morphology, microporous volumes, and physicochemical properties of the zeolites differ significantly from each other, and thus results in considerable influence on the catalytic activity and stability. Among the five zeolites studied, ZSM-5 shows the highest aromatic yield of 34.8%, followed by MCM-22 with the aromatic yield of 21.9%. However, unlike ZSM-5 and MCM-22, the other three catalysts are inactivitive for methanol aromatization. The introduction of Ga species into ZSM-5 and MCM-22, however, can improve the aromatic yield significantly. The aromatic yields on Ga/ZSM-5 and Ga/MCM-22 reach 40.8% and 27.1%, respectively. The TG/DTA and GC analyses of the coke compounds deposited on the deactivated catalysts suggest that the five zeolites display much differences in composition, location and distribution of coke deposition.