| As a low-cost non-precious metal catalyst,CuO/CeO2 shows good performance in catalyzing CO oxidation at low temperature.The impregnation method is a relatively common type of catalyst preparation method.In this project,a series of CuO/CeO2 were prepared by improving impregnation method for CO oxidation reaction.The effect of pH value of impregnation solution on the structure and activity of CuO/CeO2 catalyst were investigated firstly,and some of the catalysts were tested when water and CO2 resisted.Then ethylene glycol（EG）and water were used as solvent to investigate the effect of volume ratio of EG and H2O on the activity of CuO/CeO2 catalyst.Finally,the effect of ultrasonic impregnation method on the catalytic activity was investigated,and the effect of different copper molar content and different roasting temperature on the structure and activity of the catalysts were studied.And using XRD,XPS,H2-TPR,Raman,CO-TPD,H2O-TPD,TEM,in situ DRIFTS and other methods to characterize the physical and chemical properties of the above catalysts,analyze the relationship between the structure and performance of the catalysts.The specific research results are as follows:1.On the basis of the ordinary impregnation method,CuO/CeO2 catalysts with different pH of impregnation solution were prepared by adjusting the acidity of impregnation solution with nitric acid.The pH value of the copper salt impregnation solution was set to 0.01,1.0,2.0,2.8（the pH value of the impregnation solution when no acid was added）.Studies have found that when the acidity of the copper salt impregnation solution increased to pH=1.0,the activity of the catalyst was significantly improved.However,as the pH of the impregnating solution continued to decrease,the catalyst activity did not increase all the time,but reached a stable value.Properly increasing the acidity of the impregnating solution is more conducive for high dispersion of Cu species,and the reducing ability of CuO/CeO2 active species is greatly improved.2.Use EG and H2O as solvent to prepare different series of CuO/CeO2 catalysts by changing the volume ratio of the EG and H2O.The results show that the addition of ethylene glycol is conducive to the improvement of catalytic activity to a certain extent,but as the volume ratio of EG in the solvent gradually increases,there was little difference in the activity of the catalyst.Generally speaking,the catalytic activity reaches a best effect when VEF:VH2O=2:2.EG can improve the contact interface of copper and cerium by reducing the surface tension,so that more CuO is highly dispersed on the surface of CeO2,thereby improving the activity of the catalyst.3.The ultrasonic-assisted impregnation method was used to improve the ordinary impregnation method,and the activity changes of catalysts with different Cu molar content（5%,15%,30%）and different carrier calcination temperatures（250 0C,400 0C,700 0C）prepared by the ultrasonic-assisted impregnation method were also investigated.The result shows that the activity of the ultrasonic-assisted impregnation method is higher than that of the ordinary impregnation method.and the activity of the catalyst prepared by the ultrasonic-assisted impregnation method is the best when the Cu molar content is 15%and the carrier is calcined at 400℃. |
