改性纳米ZSM-11分子筛及其催化苯与甲醇烷基化反应的性能

The Catalytic Performance Evaluation of Acid-Base Modified Nano-ZSM-11 Zeolite on Alkylation of Benzene with Methanol to Prepare Toluene

采用先NaOH溶液碱处理后用柠檬酸溶液酸处理的方法对纳米ZSM-11分子筛进行改性.采用X射线衍射(XRD)、N_2吸附-脱附、扫描电镜(FE-SEM)、NH_3-TPD和热重(TG)等技术对改性前后的样品进行表征,将得到的催化剂应用于苯与甲醇烷基化制甲苯反应,结果表明:采用经改性处理的纳米ZSM-11分子筛催化剂,在反应温度为350℃,压力为0.2 MPa,质量空速(WHSV)为6 h^(-1),苯与甲醇进料摩尔比为1∶1的条件下,苯与甲醇烷基化反应产物中甲苯选择性明显提高,苯转化率达到44.7%,甲苯和二甲苯总选择性达到97.4%,其中甲苯选择性为86.5%,甲苯收率为37.8%.

ZSM-11 were modified by citric acid solution acid after NaOH solution alkali treatment. The catalyst were Characterized by X-ray diffraction（ XRD）,N2 adsorption-desorption,scanning electron microscopy（ FESEM）,NH3-TPD,thermogravimetry and other methods,using the modified catalyst on alkylation of benzene with methanol to prepare toluene. The result showed that the selectivity of toluene increased obviously over the nanoZSM-11 zeolite treated by acid-base on alkylation of benzene with methanol,under the conditions of the reaction temperature 350 ℃,the pressure 0.2 MPa,WHSV = 6 h^-1,n（ C6H6） ∶ n（ CH3OH） = 1 ∶ 1. The conversion of benzene reached 44. 7% ,the selectivity of toluene reached 86. 5% ,the selectivity of toluene and xylene was 97.4% ,the yield of toluene was 37.8% .