【摘要】 研究了常规加热和微波辐射两种加热方法对正己烷在ZnNi/HZSM-5催化剂上的芳构化反应的影响。考察了温度、空速对反应性能的影响,并利用XRD对ZnNi/HZSM-5催化剂作了表征。结果表明,金属锌和镍高度分散于HZSM-5沸石中,微波辐射对分子筛结构的影响很小。与常规加热反应相比,要达到相同的芳烃收率,在微波加热条件下能使反应温度降低约100℃左右。在一定程度上提高反应温度可以获得较高的总芳烃收率和BTX收率,亦能明显地改变BTX中各组分的相对选择性。改变空速能显著影响总芳烃收率和BTX收率,在常规加热和微波加热条件下的最佳空速分别为1.5h-1和1.0h-1。讨论了正己烷在微波辐射下ZnNi/HZSM-5上的芳构化反应机理。正己烷首先裂解为C03+C=3,一部分烯烃齐聚、环化生成芳烃,另一部分烯烃则经氢转移或加氢生成烷烃,C03和C04在锌和镍活性中心上直接脱氢二聚环化生成芳烃。更多还原

【Abstract】 The aromatization reaction of n-hexane under conventional heating and by microwave irradiation over ZnNi/HZSM-5 catalyst was studied, and the effect of factors, such as reaction temperature, space velocity was examined, the catalyst of ZnNi/HZSM-5 was characterized by X-ray powder diffraction. The results show that the zinc and nickel are dispersed well on support respectively with less influence on the frame structure of HZSM-5 by microwave irradiation. With the same aromatics yield, the reaction temperature is lowered about 100 ℃ under microwave heating compared with that under conventional heating. Raising reaction temperature to certain extent can obviously increase both the yields of aromaticsand benzene, toluene and xylene, influence the relative selectivity of benzene, toluene and xylene. Furthermore, changing space velocity can affect the yields of aromatics and benzene, toluene and xylene obviously, under conventional heating and microwave irradiation, the optimum space velocity is 1.5 h-1 and 1.0 h-1. Mechanism for n-hexane aromatization on ZnNi/HZSM-5 catalyst by microwave irradiation is discussed on the basis of the experimental results. Firstly, n-hexane decomposed into C03+C=3, then a part of alkene is transferred into aromatics by oligomerization and cyclization, and another part of alkene into alkane. Through dehydrogenation, dimerization and cyclization, the components of C03 and C04 are transferred into aromatics directly on the active sites of zinc and nickel.更多还原