Three-dimensional Mesoporous CeO₂ Based Catalysts With Tunable Architectures And Their Application In The CO Catalytic Oxidation

CO oxidation is very important in many applications including air purification and pollution control devices,automotive emission control,gas purification of the hydrogen to feed PEM fuel cells,closedcycle CO2 lasers and CO gas sensors,trace CO will have a great effect on the human body in a closed space.Catalytic oxidation technology is the most effective means to eliminate CO.The key point is the development of high activity and stability of the catalyst.Since the introduction of the nanocasting（hard templating）pathway,increasing efforts have been devoted to the preparation of ordered mesoporous metal oxides,These materials have high surface area and highly porous structures compared to bulk materials,and therefore can be used as efficient catalyst supports and as catalysts themselves for CO oxidation.Therefore,it is of both theorectical and practical significance to develop the channel structure influence on the catalytic activity of mesoporous metal oxides catalysts.In this paper,by adjusting the KIT-6 synthetic conditions to control the KIT-6pore structure,and as hard template,using nanocasting technology,preparation of controllable porous 3DOM CuCeOx catalysts and by adjusting the calcination temperature of preparing a series of different channel structures of 3DOM CuCeOx catalyst.Using the results of XRD,BET,TEM,H₂-TPR,XPS characterization techniques,research KIT-6 molecular sieve pore structure change on the influence of the structural characteristics of 3DOM CuCeOx catalyst and calcination temperature on the impact of 3DOM CuCeOx catalyst structure,as well as the influence on the catalytic activity of CO,exploreoing CO catalytic oxidation reaction mechanism,establishing the relationship between three-dimensional ordered mesoporous metal oxides channel structure,surface adsorption oxygen concentration,and the catalyst activity.This paper has carried out the following two aspects:（1）By controlling the hydrothermal synthesis time,mesoporous silica KIT-6with different pores were prepared.Then,the 3DOM CuCeOx catalysts were synthesized by nano-replication technology with KIT-6 as hard template.Through the analysis of the characterization,investigated the hydrothermal synthesis time influence of KIT-6 on CeCuOx pore structure,and then studied its influence on the catalytic activity of CO.When the synthesis time of KIT-6 was 24 h,this catalyst showed the highest catalytic activity.CeCu20-KIT-6-24 possessed large pore volume,small grain size,and a three-dimensional mesoporous structure.Large pore volume and small grain size increase more surface active sites,three-dimensional mesoporouschannel is more conducive to the dispersion of active components and the spread of the adsorption of reactant and product.（2）By controlling the calcination temperature,the 3DOM CuCeOx catalysts with different pores were synthesized by nano-replication technology with KIT-6-24 as hard template,and then studied the effect of diffrent pore structure on the catalyst performance.Compared CO catalyst activity of 3OM CeCuOx catalysts with the different calcination temperature,respectively 400,500,600,700 oC,the results showed that the CeCu20-600 showed a highest catalytic activity for CO oxidation,and the T100 value is 55 oC.A better catalytic activity for CO oxidation could be achieved over the catalyst a smaller grain size,the larger specific surface area and high surface active oxygen concentration.