Zn-Pt-Re/ZSM-5芳构化催化剂的研究

以正己烷为模型化合物，在固定床连续微型反应器上研究改性金属Zn含量以及助剂Pt和Re含量对Zn-Pt-Re/ZSM-5催化剂的酸性和芳构化反应性能的影响，同时考察反应条件对正己烷在Zn-Pt-Re/HZSM-5催化剂上芳构化反应性能的影响。结果表明，随着Zn含量的增加，催化剂的B酸量逐渐增加，L酸量逐渐减少。Pt和Re有利于提高催化剂的B酸量，其中Re的作用尤为显著。烷烃的芳构化反应是B酸和L酸协同作用的结果，B酸/L酸量比在0.2左右有利于提高芳烃收率，芳烃收率与催化剂中强酸的变化趋势有着很好的对应关系。反应温度的升高有利于芳构化反应的进行，当反应温度高于450 ℃时芳烃收率均在95％以上；升高反应压力和增加体积空速都不利于芳构化反应的进行。正己烷在Zn-Pt-Re/HZSM-5催化剂上芳构化反应的最佳条件为：温度450 ℃，压力1.0 MPa，体积空速1.0 h-1。

A STUDY OF Zn-Pt-Re/ZSM-5 AROMATIZATION CATALYST

The influences of Zn, Pt and Re contents on the acidity and aromatization performance of Zn-Pt-Re/ZSM-5 catalyst were studied. The effect of reaction conditions, such as reaction temperature, pressure and volume space velocity (LHSV) on the performance of Zn-Pt-Re/ZSM-5 catalyst was investigated in a continuous flow micro-reactor using n-hexane as probe molecule. Test results showed that with the increase of Zn content in catalyst, the amount of Br?nsted (B) acid sites increased and Lewis (L) acid sites decreased gradually. The existence of Pt and Re (esp. Re) in catalyst was beneficial for increasing the amount of B acid sites. It was found that the alkane aromatization was the synergetic effect of B acid and L acid, and the aromatics yield could be enhanced when B/L ratio was about 0.2. There was a very good corresponding relationship between aromatics yield and the changing trend of medium-strong acid amount of catalyst. High reaction temperature was favored to aromatization reactions, an aromatics yield of over 95% could be obtained when the reaction temperature was over 450 ℃. However, high reaction pressure and high LHSV had negative effect on the conversion and aromatics yield. The optimum reaction conditions for aromatization of n-hexane over Zn-Pt-Re/ZSM-5 catalyst were obtained as follows：a reaction temperature of 450 ℃，a reaction pressure of 1.0 MPa and LHSV of 1.0 h-1.