Effect Of Preparation Method Of Support Of CuO/CeO₂ Catalysts On Catalytic Performance For CO Preferential Oxidation

The CO preferential oxidation（CO PROX）is the most effective and promising method for the remove of CO in the H₂-rich stream.In this work,we adopted four methods to prepare CeO₂ support.The CuO/CeO₂ catalysts prepared by using these CeO₂ as supports were detailedly characterized,and their catalytic performance for CO PROX was investigated.We prepared the superfine Ce（OH）₃ nanowires and calcined them at 250℃ to get the CeO₂ support（Ce250）with large amount of surface defects and high specific surface area.Ce250 was supported with 10%CuO and then were calcined at different temperature to get a series of CuCeX catalysts.The catalytic performance for CO PROX over the CuCeX catalysts was tested.The CuCeX catalysts were characterized with BET,XRD,UV-Raman,H₂-TPR,XPS and Cu K-edge XAFS techniques.Compared with the support prepared by calcining the superfine Ce（OH）₃ nanowires at higher temperature or the support prepared by precipitation method,the Ce250 shows much more surface defects,which is beneficial for the strength of the interaction between CuO and CeO₂.The interaction between CuO and CeO₂ is the main factor to affect catalytic performance for CO PROX and is strengthed with the increase of the calcination temperature,so the intrinsic activity of the catalysts is increased with the increase of the calcination temperature.However,as the specific surface area of CuCe500 is much higher than CuCe600,the apparent activity of CuCe500 is the highest with the lowest 50%and 100%CO convention temperature at 71 and 100℃,respectively,and the temperature window for CO full convention is 100-161℃.The CeO₂ supports were prepared by oxalate thermal decomposition,nanowire breaking method,urea thermal decomposition method and precipitation method,respectively.After loaded with 10%CuO,the catalysts were used for the CO PROX reactions.The catalysts were characterized by BET,XRD and H₂-TPR techniques.The results show that the catalysts prepared by oxalate thermal decomposition–impregnation method has the strongest interaction between CuO and CeO₂ and high specific surface area,so has the highest CO PROX activity with the CO full convention temperature of 98℃ and the full convention window of 98-160℃.A series of CuO/CeO₂ catalysts with different CuO loading were prepared by oxalate thermal decomposition–impregnation method and used for the CO PROX reaction.The catalysts were characterized by TEM,HRTEM,BET,XRD,UV-Raman,H₂-TPR and XPS techniques.For all the catalysts,CuCe solid solution may be formed during the preparation process,which would introduce more surface oxygen vacancy and Ce³⁺.As the interaction between CuO and Ce O₂,Many active sites of Cu⁺would be formed due to the interaction between CuO and CeO₂,and it improves the catalysts activity.As the 10%Cu Ce catalyst has the strongest CuCe interaction and the most amount of surface Ce³⁺content,it has the higest CO PROX activity with the CO full convention temperature at 98℃,and the window temperature for CO full convension is 98-160℃.