Preparation And Properties Of CeO₂-MO_x?M=Zn/Mn/Cu? Porous Composites

Porous CeO₂ is widely used due to its superior oxygen storage and release capacity,higher specific surface area,smaller grain size and better mass transfer efficiency.CeO₂ can provide more active sites in catalytic reacion.Combining CeO₂ with other catalysis is beneficial to exert the synergistic effect between different materials and improve catalytic performance.However,the synthetic methods of CeO₂-based porous composites are usually complicated,which limits their practical applications.In this paper,a variety of CeO₂-based porous composites were prepared by one-step solvothermal method followed by calcination.The structure,composition and surface valence of the material can be flexibly adjusted,which paves a new way for the preparation of CeO₂-based porous materials.This paper focuses on the catalytic performance and corresponding reaction mechanism of the prepared CeO₂-based porous composites in acetone detection,NO oxidation and 4-NP reduction,and proposes a structure-activity relationship between the properties and the material composition.The main research contents are as follows:?1?CeO₂-ZnO porous composites were prepared by solvothermal method combined with calcination,and the formation mechanism of the material was proposed.The important role of material surface defects and Ce3+in acetone oxidation were proved,by studying the performance of sensors based on PZC porous composite materials in acetone detection.?2?The method of preparing CeO₂-ZnO porous composite material was successfully extended to the preparation of CeO₂-CoO_x,CeO₂-Fe₂O₃,CeO₂-MnO_x and other CeO₂-metal oxide composite materials.It was found that in these materials,the size of the internal cavities increased significantlying.The structure and performance of CeO₂-MnO_x?PMC?composite materials were investigated in detail with Ce feed ratios of 30%,20%and 10%respectively.In addition,it has been shown that the PMC-2 with a cerium content of only 20%have the highest activity for the catalytic oxidation of NO,which is attributed to the enrichment of cerium element and high content of Mn4+ on the surface.When GHSV=120000 h-1,the maximum conversion of NO at 270? is 90.6%.At the same time,it meets the requirements of the catalyst for real appilication,that is low cerium content,simple synthesis method and excellent performance.?3?The hollow composite of CeO₂ and metal Cu was synthesized by solvothermal method.After different post-treatments,CeO₂-Cu2O and CeO₂-CuO hollow composites were prepared respectively.Due to their similar particle size,similar Ce/Cu ratio and specific surface area,the comparative analysis of the catalytic activity of CeO₂-CuxO?x=1,2?composite materials reduces the impact of macroscopic differences in materials.The influence of macroscopic differences in the materials were reduced when comparing and analyzing the catalytic activity of CeO₂-CuxO?x=1,2?composite materials.The results show that the in-situ generated CuO with highly active,unrelated with the initial state of copper.CeO₂-Cu₂O shows higher catalytic activity and better reproducibility in the reduce reaction of 4-NP with NaBH₄,due to its small grain size and a large number of oxygen vacancies.