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美国Mobil公司开发的ZSM系列高硅沸石分子筛催化剂,因其具有优良的择形性和热稳定性而广泛地应用于甲苯歧化、烷烃芳构化、芳烃烷基化等一系列重要化学反应的催化过程据报道,改性的HZSM—5分子筛催化剂用于甲苯甲醇烷基化反应,可使对二甲苯含量达90％以上,产物不经分离便可直接用于聚酯生产。一般认为沸石具有许多强酸中心,并能催化以正碳离子机制进行的反应。因此,分子筛的表面酸度及酸强度分布对催化活性和选择性应有较大的影响。我们以MgO为改性物质,对HZSM—5沸石分子筛进行改性,用吡啶中毒脉冲气相色谱保留体积法测定了改性的HZSM—5分子筛的酸度和酸强度分布,用微反脉冲色谱法测定了甲苯烷基化反应和间二甲苯异构化反应的活性及选择性,并把它们的催化性质和酸性质进行了关联。
Developed by the United States Mobil ZSM series of high-silica zeolite catalyst, because of its excellent shape selectivity and thermal stability and is widely used in toluene disproportionation, paraffin aromatization, aromatics alkylation and a series of important chemical reactions catalyzed Process It has been reported that the modified HZSM-5 molecular sieve catalyst for the toluene methanol alkylation reaction can be p-xylene content of 90% or more, the product can be used directly without separation of polyester production. It is generally believed that zeolites have many strong acid sites and can catalyze reactions that are carried out by the positive carbon ion mechanism. Therefore, the molecular sieve surface acidity and acid strength distribution on the catalytic activity and selectivity should have a greater impact. We modified the HZSM-5 zeolite with MgO as a modified substance, and determined the acidity and acid strength distribution of the modified HZSM-5 molecular sieve by the gas-in-pulse retention volumetric method of pyridine poisoning. The micro-reversed-pulse chromatography The activity and selectivity of the toluene alkylation and m-xylene isomerization reactions were correlated and their catalytic and acid properties were correlated.