Preparation Of Novel Hybrid Nanostructure Platinum Catalysts And Study On Their Performance For CO Lowtemperature Complete Catalytic Oxidation

CO catalytic oxidation plays an important role in chemical energy conversion and gas pollutant control.it is a basic step in WGS reaction,and a key step for removing CO from reformed H₂in fuel cell.As an important catalytic model reaction,CO catalytic oxidation has far-reaching research value.The catalytic oxidation of CO has the advantages of low energy consumption and good removal effect for low concentration CO.the supported noble metal catalysts have been widely concerned because of their high catalytic activity for CO and good catalytic effect at low temperature.However,they also have the disadvantages of high price and easy loss of active components.In recent years,the single atom catalyst has achieved the maximum utilization of metal atoms,but it is difficult to control the aggregation of active components and the loss of activity.Therefore,accurate design and preparation of CO oxidation catalyst with low temperature,high activity and high stability has always been a difficult problem for CO catalytic oxidation.This paper provides a new strategy for the preparation of supported Pt catalyst that metal oxide semiconductor is coated firstly on the support with high specific surface area to form a composite support,and then Pt is loaded on it to form a novel hybrid nanostructured Pt catalyst.Firstly,FeO_xor CeO₂was coated on SiO₂and SBA-15 by DP method to form composite supports FeO_x/SiO₂,@-FeO_x/SBA-15and@-CeO₂/SBA-15 based on the principle of spontaneous monolayer dispersion.Then,Pt NPs was loaded on the composite supports to form Pt/FeO_x/SiO₂,Pt/@-FeO_x/SBA-15 and Pt/@-CeO₂/SBA-15 based on the photoreductivity of semiconductor metal oxides.The structure and morphology of the catalysts were analyzed by N₂adsorption-desorption,XRD,XPS,TEM and ICP.The catalytic performance of CO Low-temperature catalytic oxidation was systematically investigated.The catalytic activity was further improved by doping with alkali metal Na and transition metal Ni.The mechanism of CO oxidation of Pt and semiconductor metal oxides was investigated by CO-TPD and H₂-TPR.We found that the prepared catalyst was a novel hybrid nanostructure with Pt nanoparticles anchored in the semiconductor film,in which FeO_xwas first distributed on the high surface area support in single or multi-layers,and then Pt NPs was supported on FeO_x.The results show that there is a synergistic effect between Pt and FeO_x.The existence of FeO_xfilm promotes CO to overflow from Pt adsorption site to FeO_xafter adsorption and activation at Pt site,which improves CO activation ability.Compared with Pt/FeO_x,Pt/SiO₂and Pt/SBA-15,the catalytic activity of hybrid nanostructured Pt catalysts for CO oxidation is greatly improved,and CO can be completely converted at 120℃.In addition,the addition of Ni or Na can greatly improve the catalytic activity of Pt/@-FeO_x/SBA-15.The addition of Na can reduce the size of Pt particles and make a kind of Fe species with high reducibility in FeO_x,which can improves the redox cycle characteristics of FeO_x,so that the catalyst can complete convert CO at room temperature.In addition,the metal oxide semiconductor FeO_xsupported on hybrid nanostructured Pt catalyst can be extended to CeO₂,which indicates the novel hybrid Nanostructure benefits to the catalytic performance of the catalyst for CO oxidation.