摘要
采用共沉淀法先制备出Co/ZrO2 催化剂前驱体.经喷雾干燥成型后,再利用水热法将高水热稳定性的H-ZSM-5 分子筛原位生长在球形Co/ZrO2 催化剂前驱体上,制备出掺杂分子筛Co/ZrO2-H-ZSM-5 催化剂.XRD表征显示掺杂分子筛后,Co3O4 的特征峰仍然保留且晶粒尺寸并未因掺杂而变化,并出现明显的H-ZSM-5 特征峰.BET测试显示由于掺杂分子筛,其比较面积随掺杂量增加而提高.HRTEM 表征结果显示规则晶体形貌的H-ZSM-5 分子筛吸附在Co/ZrO2 催化剂上.H2-TPR与NH3-TPD测试结果则显示,由于掺杂H-ZSM-5 分子筛,导致还原度小幅降低,但是提高了催化剂酸性位强度.固定床费托合成催化性能评价结果也显示,由于掺杂酸性H-ZSM-5 分子筛,CO加氢生成的长链碳氢化合物会在分子筛上裂解,异构化,进而提高异构烷烃的选择性.
Abstract
Co/ZrO2 catalyst precursor was prepared by coprecipitation method.After spray drying,stable H-ZSM-5 zeolite was grown on the spherical Co/ZrO2 catalyst precursor by hydrothermal method,and Co/ZrO2-H-ZSM-5 catalyst was prepared after calcination.XRD characterizations showed that the characteristic peak of Co3O4 remain and the particle size did not change after doping,and the characteristic peak of H-ZSM-5 appeared obviously.BET characterization showed that surface area increased with the increase of doped zeolite content.HRTEM results illuminated that H-ZSM-5 zeolite with regular morphology adsorbed on Co/ZrO2 catalysts.Testing results of H2-TPR and NH3-TPD showed that doped H-ZSM-5 zeolite resulted in a slight reduction in the reducibility but an increase in the acid site strength of the catalyst.The results of catalytic performance evaluation of Fischer-Tropsch synthesis in the fixed-bed reactor also showed that the longer chain hydrocarbons produced by CO hydrogenation was cracked and isomerized in the acidic H-ZSM-5 zeolite,and thus improved the selectivity of isoparaffins.
维普
万方数据