Preparation Of CuO-loaded CeO 2 -based Catalyst And Study Of Its CO Oxidation Activity

With the improvement of people's living standards,the number of motor vehicles has also increased,which causes the further deterioration of the environment,the attention of motor vehicle exhaust treatment again and again upgrade.When selecting the appropriate catalyst,because CO as one of the main components of the exhaust,the catalyst with a higher oxidation activity is more popular.And the synthesis of low cost and high CO oxidation catalytic activity of the catalytic material is particularly important.CeO₂-based carrier is a good choice for the catalyst carrier due to the large amounts of oxygen vacancy and its abundant resource reserves and low price.Crystal defects tend to generate more lattice vacancies,which can act as potential oxygen adsorption sites,in order to maximize these active sites,So we tend to introduce a variety of other elements to the CeO₂ lattice,and thus the catalyst will be higher oxygen storage capacity and high temperature thermal stability.In this paper,the CeO₂-based carrier was synthesized by coprecipitation method which is easy to be realized in the industry,and the thermal stability of the carrier was improved by adding Zr and other elements.The CeO₂-based carrier was modified by wet impregnation method to prepare the CeO₂ catalytic materials with a Higher CO oxidation activity,We made the following main research results.1.The effects of different raw materials on the physical and chemical properties of CeO₂ carriers under the same preparation conditions were studied.The results show that CeO₂ synthetized by H₂Ce?NO₃?₆ has a larger specific surface area at roasting conditions of 800 ? /3 h.The CeO₂ carrier synthetized by H₂Ce?NO₃?₆ has a large surface reduction peak at 300⁶00 ?,although its reduction ability is less than that CeO₂ carrier prepared of?NH₄?₂Ce?NO₃?₆ as raw material,but its thermal stability is higher than that CeO₂ carrier prepared of?NH₄?₂Ce?NO₃?₆ as raw material.The results show that CeO₂ carrier synthesized with cerium nitrate as raw material has better high temperature specific surface area and better reducing ability.2.The CeO₂-ZrO₂ solid solution doped La₂O₃?5%?and Y₂O₃?5%?was synthesized by the method of reverse coprecipitation which is easy to be realized in the industry.The effects of different concentration,dropping time,hydrogen peroxide and oxide mass ratio and stirring speed on the properties of the synthesized carrier were studied by orthogonal experiment.The results show that when the concentration of water was 0.10 g / ml,the dropping time was 70 min,the ratio of hydrogen peroxide and oxide was 1:1,and the stirring speed was 170 r / min,the specific surface area is 27.52 m2/g which was the largest corresponding to roasting conditions of 1000 ?/4 h.3.CuO/CeO₂?C/C?,CuO/CeO₂-Zr O₂?C/CZ?andCu O/La₂O₃-Y₂O₃-CeO₂-ZrO₂?C/CZL Y?catalysts were prepared by wet impregnation method which is easy to be realized in the industry.From the TEM maps,the results show that the loading of CuO in the C/CZLY catalyst with 8% loading is uniform and the CuO particle size is small.From the H₂-TPR graph,it was found that 8%C/CZLY has the strongest reduction capability and has the lowest level of reduction capability and has the widest range of reduction capabilities.So its comprehensive ability to restore is the best.From the fresh catalyst CO catalytic experiments,we found that the T₅₀ of C/C and C/CZ is resoectively 94 ? and 99 ?,respectively,T₉₀ is 113 ? and 115 ?,These corresponding temperatures are slightly higher than C/CZLY,but the final conversion temperature is the same.The combination shows that C/CZLY has better catalytic capacity.Found from the aging catalyst CO catalytic experiments,the T₁₀,T₅₀ and T₉₀ of C/CZLY is respectively 80 ?,120 ? and 155 ?.Compared to the C/C,which catalytic capacity is generately lower,its T₁₀,T₅₀ and T₉₀ is 100 ?,130 ? and 175 ?,significantly lower than C/CZLY.C/CZ's catalytic capacity is slightly higher than C/C,but slightly lower than C/CZLY,its T₁₀,T₅₀ and T₉₀ is 80 ?,120 ? and 155 ?.Comprehensively,it is shown that C/CZLY has a higher thermal stability and its CO oxidation catalytic ability is still the best at?800 ? /2 h?and is comparable to that of fresh catalyst.