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研究了正庚烷和丙烯在用水蒸汽和高温焙烧改性的直接法合成的HZSM-5型沸石催化剂上反应活性与产物选择性变化规律。结果表明,随水蒸汽处理和焙烧温度提高,沸石表面酸度和强酸中心数逐渐减少。在400℃以上水蒸汽处理或在650℃以上焙烧,沸石在脱羟基同时伴随骨架铝脱除,晶体孔容减少,孔口尺寸收缩。正庚浣和丙烯的反应活性随处理温度提高而降低,芳烃选择性下降,C_5~+脂肪烃含量增加,目的产物汽油收率提高;沸石形选性增加,p/o值急剧增大。两种不同方法改性的HDZ沸石反应活性和产物选择性有完全相似的变化规律。此外,考察了HDZ沸石失活特征和水蒸汽处理对结炭的影响。
The variation of reactivity and product selectivity of HZSM-5 zeolite catalysts synthesized by direct reaction of n-heptane and propylene with steam and high temperature calcination were studied. The results showed that with the increase of steam treatment and calcination temperature, the surface acidity and the number of strong acid centers gradually decreased. At 400 ℃ or above steam treatment or calcination at 650 ℃ above, the zeolite in the dehydroxy accompanied by skeleton aluminum removal, crystal pore volume reduction, pore size shrinkage. The reaction activity of n-heptane and propylene decreased with the increase of treatment temperature, the selectivity of aromatics decreased, the content of C_5 ~ + aliphatic hydrocarbons increased, the yield of gasoline of the target product increased; the selectivity of zeolite increased and p / o increased sharply. The HDZ zeolite modified by two different methods has exactly the same changing rules as the product selectivity. In addition, the deactivation characteristics of HDZ zeolite and the effect of steam treatment on the coke formation were investigated.