Study On The Selective Oxidation Of CO Under Hydrogen-rich Conditions By Copper-cerium-based Catalysts

Due to the current energy shortage,there is an urgent need for clean energies.Hydrogen has received a lot of attention as a clean energy source.And the production methods of hydrogen including reforming hydrogen and partial oxidation to produce hydrogen,etc.,but no matter how it is produced,there is always 0.5%-1vol.%CO in the generative hydrogen.Proton exchange membrane fuel cell(PEMFC)is widely applied to automotive industry and home power box mobile communications.At present,selectively oxidation of CO in the hydrogen rich gas(CO-PROX)is considered as the most economical and effective method for removing small amounts of CO.Cu Ce-based catalysts have been widely applied to CO-PROX because of their high catalytic performance and low price.Therefore,in this paper,Cu Ce-based catalysts were used to investigate the active species in the CO-PROX reaction.The main parts including the effects of different morphologies of Cu Ce catalysts and they were modified with transition metal Fe.Finally,the effects of pretreatment conditions on CO-PROX activity were investigated for Cu Ce catalysts as well.Combined with multiple material characterization techniques(N₂-adsorption and desorption,XRD,TEM,HR-TEM,SEM,EDS-mapping,H₂-TPR,XPS,Raman,CO pluses,O₂-TPD,CO-TPD,CO-DRIFTS)to explain the details of catalytic structure-performance relationship and effects of pretreatment conditions for Cu Ce-based catalysts on CO-PROX.And we can draw the following conclusions:1.Cu Ce catalysts with different morphologies have different effects on CO-PROX.The Cu Ce-S showed the best catalytic performance for CO-PROX.And the structure-property relationship was established in combination with kinetic experiment.We could make a conclusion that the decisive factor of CO-PROX is oxygen species.2.The doping of Fe has significantly increased the catalytic activity of Cu Ce catalysts for CO-PROX.The addition of Fe creates a stronger Cu-Ce interaction and enhances the oxygen mobility,which is closely related to reactive temperature.And the addition of Fe makes Cu Ce catalysts have certain resistance to H₂O and CO₂in 140?-220?.4.There is a obvious enhancement of CO-PROX activity for Cu Ce catalysts,which pretreated in H₂at 200?.In addition,the results of situ H₂-TPR show that the pretreatment in H₂has a significant effect on the interaction between Cu and Ce oxides.After H₂pretreatment,reaction gases were passed in,the reoxidation of Cu Ce catalysts occurred and the degree of reoxidation depended on the time,concentration,and temperature of the reaction gas.And the phenomenon of reoxidation for Cu Ce catalyst has happened even at room temperature.6.Pretreatment of Cu Ce catalysts in inert gases,it was found that the pretreatment at200?can significantly improve the activity of CO-PROX.This is attributed to the formation of more structural defects and the redistribution of surface elements for Cu Ce catalysts,which have pretreated in inert gas,further strengthens the Cu-Ce interaction.