College of Chemistry and Chemical Engineering, Anhui University, Hefei 230601, PR China.
J Nanosci Nanotechnol. 2020 Feb 1;20(2):1245-1252. doi: 10.1166/jnn.2020.16976.
Commercial ZSM-5 zeolites were submitted to alkaline treatment in order to prepare hierarchical ZSM-5 zeolites with hierarchical porosity and moderate acidity. Hybrid bifunctional catalyst comprising a CuO-ZnO-Al₂O₃ (CZA) and zeolite was prepared by physical mixing method, used for the direct synthesis of dimethyl ether (DME) from syngas. The correlation between the textural and acid properties of the zeolite and the catalytic performance of hybrid catalyst has been assessed from the combined results of N₂ physisorption, FTIR of adsorbed pyridine, elemental analysis ICP, online-GC and other characterization techniques. The results indicate that the hybrid catalyst with hierarchical ZSM-5 zeolite exhibits higher activity and stability than that with parent ZSM-5 zeolite due to the synergy effect of moderated acidity and enhanced mass transport capability of the hierarchical ZSM-5 sample. Under 260 °C, 2.0 MPa and 3600 h, the conversion of CO and the DME selectivity to DME over hybrid catalyst CZA-ZSM-5(25)-A achieved 65.2% and 67.8%, respectively.
商业 ZSM-5 沸石经过碱性处理，制备出具有分级孔结构和适度酸度的分级 ZSM-5 沸石。采用物理混合法制备了包含 CuO-ZnO-Al₂O₃（CZA）和沸石的双功能复合催化剂，用于从合成气直接合成二甲醚（DME）。通过 N₂物理吸附、吸附吡啶的傅里叶变换红外光谱、元素分析 ICP、在线 GC 和其他表征技术的综合结果，评估了沸石的织构和酸性质与混合催化剂的催化性能之间的相关性。结果表明，具有分级 ZSM-5 沸石的混合催化剂由于适度酸度的协同效应和分级 ZSM-5 样品增强的传质能力，表现出更高的活性和稳定性。在 260°C、2.0 MPa 和 3600 h 的条件下，混合催化剂 CZA-ZSM-5（25）-A 上 CO 的转化率和 DME 对 DME 的选择性分别达到 65.2%和 67.8%。
