Effect of ZrO_2 on CuO-ZnO-ZrO_2/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.