ZrO_2在二甲醚合成催化剂CuO-ZnO-ZrO_2/HZSM-5中的作用

采用并流共沉淀法制备了一系列不同ZrO2含量的CuO-ZnO-ZrO2甲醇合成催化剂,与HZSM-5分子筛机械混合制备了一步法合成二甲醚的双功能催化剂CuO-ZnO-ZrO2/HZSM-5,在固定床反应器中进行合成气直接制二甲醚的研究,考察了ZrO2在催化剂中的作用。结果表明,ZrO2的加入能显著提高催化剂性能,当ZrO2含量达到x(ZrO2)=0.06时,催化剂的活性、选择性较高并且耐热性能较强。而过量的ZrO2会降低催化剂的耐热性能。利用TPR?XRD对催化剂进行了表征,发现适量ZrO2的加入不仅有助于提高Cu活性组分在催化剂表面的分散,使催化剂不容易高温烧结,而且有利于促进催化剂还原。

Effect of ZrO2 on CuO-ZnO-ZrO2/HZSM-5 Bifunctional Catalysts for Direct Synthesis Dimethyl Ether from Synthesis Gas

A series of Cu-ZnO-ZrO_2 methanol synthesis catalysts with different ZrO_2 contents were prepared by coprecipitation and then mixed mechanically with HZSM-5 to obtain the bifunctional catalysts CuO-ZnO-ZrO_2/HZSM-5.The catalysts are characterized by XRD and TPR analysis and evaluated for the development of STD(synthesis gas-to-dimethyl ether) process.The addition of ZrO_2 improved the performance of the bifunctional catalysts.When the content of ZrO_2 is x(ZrO_2)=0.06,CO conversion,DME selectivity and the over-heating tolerance performance arrived the best.Based on the results of XRD and TPR analyses,it can be concluded that the addition of ZrO_2 is benefit for the active components to be dispersed finely in the bifunctional catalysts,which may prevent the catalysts from sintering at higher temperature and enhance the reduce capability of the catalysts also.