不同方法制备ZSM-11分子筛催化剂上乙醇和苯气相烷基化制乙苯

Gas Alkylation of Ethanol With Benzene Over ZSM-11 Zeolite Catalysts Synthesized via Different Preparation Methods

采用固定床反应器考察了在一定温度水热处理后无黏结剂、Al_2O_3和SiO_2黏结剂成型制备的强酸量相近ZSM-11分子筛催化剂催化乙醇和苯气相烷基化反应性能。采用X射线衍射(XRD)、N_2物理吸附-脱附、氨程序升温脱附(NH3-TPD)、吡啶吸附红外(Py-IR)和热重分析(TG)等技术手段对ZSM-11分子筛样品进行了表征。结果表明,Al_2O_3和SiO_2成型的ZSM-11催化剂(Cat-A、Cat-B)的微孔体积相近,无黏结剂ZSM-11分子筛催化剂(Cat-C)的BET比表面积最小,微孔体积最大;与Cat-A和Cat-B相比,Cat-C的强酸中Br9nsted酸/Lewis酸酸量比最高。在乙醇和苯气相烷基化反应中,乙醇未完全转化的情况下,Cat-A上苯和乙醇转化率最高。还考察了Cat-A分子筛催化剂上气相烷基化反应寿命,在500h的反应过程中,乙醇转化率可达99.9%,苯的转化率维持在12%,产物中烃类液体选择性达到98%～99%。

Gas alkylation performances of the ZSM-11 zeolite catalysts of similar strong acidity prepared via different methods,were investigated in a fixed bed reactor.The samples were characterized by X-ray diffraction(XRD),N 2 physisorption-desorption,ammonia temperature desorption process(NH 3-TPD),pyridine adsorption infrared(Py-IR)and thermogravimetric analysis(TG)methods.The ZSM-11 catalysts referred to as Cat-A and Cat-B with alumina and silica as binder,respectively,have similar micropore volume.While the none-binder ZSM-11 zeolite catalyst(Cat-C)shows the lowest BET specific surface area and largest micropore volume.In comparison with Cat-A and Cat-B,Cat-C possesses the highest molar ratio of strong Br nsted acid concentration/Lewis acid concentration.When the catalysts are used in the gas alkylation of ethanol with benzene,Cat-A exhibited the highest benzene and ethanol conversion,with ethanol conversion less 100%.Furthermore,the lifetime test of Cat-A in the gas alkylation was investigated.During the 500 h processing,ethanol conversion is 99.9%,benzene conversion remains 12%,and the hydrocarbon liquid product selectivity is around 98%-99%.