Abstract

The effect on the incorporation of zinc of three zeolites TNU-9, MCM-22, and MCM-68 was investigated. The physico-chemical properties of zeolites were studied by X‐ray diffraction, N₂-adsorption, temperature‐programmed desorption of NH₃ (TPD), nuclear magnetic resonance of ²⁷Al and ²⁹Si (MAS NMR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Then all the samples were characterized and evaluated in the reaction of methanol to aromatics (MTA). The correlation of zinc incorporation method and acidic properties of zeolites with catalytic performance was investigated. The form of zinc incorporation, the acidity, the type of zeolitic structure and the reaction temperature had a great influence on the catalytic activity. Regarding the type of structure, the total aromatics selectivity in this work increased in the followed order for zeolites modified with Zn: MCM-68 > TNU-15 > MCM-22. The medium pore zeolite T9-15 (TNU-9 zeolite and Si/Al 15 ratio) catalysts with the ratio ZnO/ZnO + Al₂O₃ equal to 0.34 (T9-15 0.5 Zn) showed better stability with conversion of methanol completes during 9 h of reaction and 17% to BTX selectivity and 32% to total aromatics compounds at 450 °C and WHSV of 4.24 h⁻¹. In methanol conversion, the selectivity to aromatics over the T9-15 modified-Zn materials (TNU-9 zeolite and Si/Al 15 ratio) under study, increased in the followed order: T9-15 0.5 Zn > ZT9-15 > T9-15 > T9-15 0.2 Zn. The reaction temperature is an important variable in the MTA process. At 450 °C a better activation of acid sites is achieved in zeolite with Zn and therefore a high percentage of BTX selectivity is obtained for TNU-9 zeolite.

中文翻译：

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锌修饰的10和12环沸石（MCM-22，TNU-9和MCM-68）的合成及其在甲醇与轻质芳烃和烯烃反应中的潜在应用

摘要

研究了三种沸石TNU-9，MCM-22和MCM-68对锌结合的影响。通过X射线衍射，N ₂吸附，NH ₃（TPD）的程序升温脱附，²⁷ Al和^29的核磁共振研究了沸石的理化性质。Si（MAS NMR），扫描电子显微镜（SEM）和热重分析（TGA）。然后，在甲醇与芳烃（MTA）的反应中对所有样品进行表征和评估。研究了锌的掺入方法和沸石的酸性与催化性能的关系。锌的引入形式，酸度，沸石结构类型和反应温度对催化活性有很大影响。关于结构的类型，这项工作中总的芳香族化合物选择性按以下顺序增加：用Zn改性的沸石：MCM-68> TNU-15> MCM-22。ZnO / ZnO + Al ₂ O ₃比率的中孔沸石T9-15（TNU-9沸石和Si / Al 15比率）催化剂等于0.34（T9-15 0.5 Zn）表现出更好的稳定性，在450°C和4.24 h ^-1的WHSV下，甲醇在9小时反应完全完成转化，对BTX的选择性为17％，对全部芳香族化合物的转化为32％。在甲醇转化中，所研究的T9-15改性锌材料（TNU-9沸石和Si / Al 15比率）对芳烃的选择性按以下顺序增加：T9-15 0.5 Zn> ZT9-15> T9- 15> T9-15 0.2锌。反应温度是MTA过程中的重要变量。在450°C下，含Zn的沸石可以更好地活化酸位，因此，对于TNU-9沸石，BTX的选择性很高。