碱改性HZSM-5分子筛催化噻吩烷基化性能的研究

摘要

分别采用Na2CO3,Na2CO3/十六烷基三甲基溴化铵(CTAB)混合碱对HZSM-5分子筛进行改性处理,利用X射线衍射仪(XRD)、BET法、扫描电子显微镜(SEM)、N2等温吸附脱附、氨程序升温脱附(NH3-TPD)等分析手段对碱处理前后的分子筛进行了表征,并考察了碱处理前后HZSM-5分子筛催化噻吩烷基化的性能.结果表明:采用Na2CO3/CTAB混合碱处理商业HZSM-5分子筛[n(SiO2)(Al2O3)为50],在Na2CO3溶液浓度为4 mol/L,c(CTAB)/c(Na2CO3)为0.050的最优条件下,分子筛的比表面积由改性前的318 m2/g增大到485 m2/g,催化噻吩烷基化反应的噻吩转化率、选择性则分别由改性前的35.47％,58.32％依次提高到93.57％,79.68％.%HZSM-5 molecular sieve was modified by Na2CO3 solutions and Na2CO3/CTAB mixed alkali solutions respectively.The samples before and after alkali treatment were characterized by XRD,BET,N2 adsorption-desorption,SEM and NH3-TPD analysis methods,and the catalytic performance for thiophene alkylation of the samples before and after alkali treatment were investigated.The results showed that when the commerical HZSM-5 molecular sieve [n(SiO2)(Al2O3) =50] was treated by Na2CO3/CTAB mixed alkali,and the optimal conditions of the molar concentration of Na2CO3 solutions was 4 mol/L and c (CTAB)/c (Na2CO3) was 0.050,the specific surface area of the molecular sieve increased from 318 m2/g to 485 m2/g,and the thiophene conversion and selectivity of the catalytic thiophene alkylation reaction increased from 35.47％ and 58.32％ to 93.57％ and 79.68％ respectively.