碱酸改性ZSM-5分子筛催化剂的噻吩烷基化反应性能研究

以SiO_2/Al_2O_3物质的量比为50的HZSM-5分子筛为原粉,经过一定浓度的NaOH溶液处理后再使用柠檬酸溶液进行酸洗以制备微孔-介孔多级孔HZSM-5催化剂,并研究其在模拟油中的噻吩烷基化反应性能。结果表明,使用柠檬酸溶液进行酸洗可以清除碱处理后孔道内残余的杂质。当柠檬酸溶液浓度为0.5 mol/L时,此时得到的HZ(AC-0.5)催化剂具有适宜的孔径和酸性,因而噻吩烷基化转化率最高,达到95.6%。在HZ(AC-0.5)催化剂上以苯并噻吩作为噻吩衍生物模型化合物,异戊二烯作为烯烃模型化合物,苯作为芳烃模型化合物,分别考察噻吩烷基化反应性能,并分析不同组分的模拟油对噻吩烷基化反应转化率和选择性的影响。结果表明,噻吩烷基化的最佳反应温度是120℃,在该温度下苯并噻吩烷基化的转化率高于噻吩烷基化的转化率,当异戊二烯作为烯烃模型化合物后噻吩的转化率会升高,当苯作为芳烃模型化合物后噻吩的转化率会降低。

Study on the performance of alkali acid modified ZSM-5 catalysts for thiophene alkylation reaction

HZSM-5 zeolites with SiO₂/Al₂O₃ molar ratio of 50 as the raw material were treated by a certain concentration of NaOH and then impregnated with citric acid solution to prepare microporous and mesoporous hierarchical HZSM-5 catalyst. The catalytic performance of the prepared catalysts for thiophene alkylation reaction was investigated using simulated oil. The results show that the residual impurities in the pores after alkali treatment can be eliminated by acid washing with citric acid solution. When the concentration of the citric acid solution is 0.5 mol/L, the HZ(AC-0.5) catalyst has the appropriate pore size and acidity, so the conversion of thiophene alkylation is the highest, which is up to 95.6%. The performance of thiophene alkylation reaction was also investigated by respectively using dibenzothiophene thiophene derivatives as model compounds, olefin isoprene as model compounds, aromatic benzene as model compound on the HZ (AC-0.5) catalyst. And then we analyzed the influence of different components in the simulated oil on the conversion and selectivity of thiophene alkylation reaction. It has been demonstrated that the optimum reaction temperature of thiophene alkylation reaction is 120℃. At the optimum temperature, the conversion of benothiophene alkylation is higher than that of thiophene alkylation. The conversion of thiophene will be increased when the olefin isoprene is used as model compound. The conversion of thiophene will be decreased when benzene is used as aromatic model compound.