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以咪唑为添加剂,四丙基氢氧化铵为模板剂,采用水热法制备了咪唑改性HZSM-5型分子筛,用XRD、SEM、EDS、BET、TG和NH3-TPD对合成的分子筛进行了表征。结果表明,当在制备分子筛的前驱液中加入少量咪唑时,制备的HZSM-5型分子筛粒径明显减小且分布更加均匀,酸性增强,并具有更好的抗高温性能。采用浸渍法制备了CuO-ZnO-Al2O3/咪唑改性HZSM-5双功能催化剂,探讨了其催化二氧化碳加氢制备二甲醚的活性,在反应温度270℃、反应压力3.0 MPa、V(CO2)∶V(H2)=1∶3、n(CuO)∶n(ZnO)=2∶1和m(CuO-ZnO2-Al2O3)∶m(咪唑改性HZSM-5)=2∶1的条件下,CO2的单程转化率和二甲醚的选择性分别达到了42.3%和33.1%。
The imidazole-modified HZSM-5 molecular sieve was prepared by hydrothermal method using imidazole as additive and tetrapropylammonium hydroxide as template. The synthesized molecular sieves were characterized by XRD, SEM, EDS, BET, TG and NH3-TPD Characterization. The results showed that when a small amount of imidazole was added into the precursor of molecular sieve, the size of HZSM-5 molecular sieve was obviously reduced and its distribution was more uniform, the acidity was enhanced and the better high temperature resistance was obtained. CuO-ZnO-Al2O3 / imidazole modified HZSM-5 bifunctional catalyst was prepared by impregnation method. The catalytic activity of hydrogenation of carbon dioxide to dimethyl ether was studied. The reaction temperature was 270 ℃, reaction pressure was 3.0 MPa, Under the conditions of 2: 1 (V (H2) = 1: 3, n (CuO): n (ZnO) = 2: 1 and m (CuO-ZnO2- Al2O3): m (imidazole modified HZSM- The one-way CO2 conversion and DME selectivity reached 42.3% and 33.1% respectively.