Au Loaded And Cu-doped CeO₂ Nanomaterials:Preparation And Investigation Of Their Properties For Co Catalytic Oxidation

CeO₂ is a cheap rare earth oxide with abundant oxygen vacancies and oxygen storage capacities.The easy conversion of Ce³⁺/Ce⁴⁺makes it have good redox ability.Therefore,it has extensive application in the field of catalysis,such as CO oxidation and 4-NP reduction.Thus,the further improvement the catalytic activity of CeO₂ has been a problem for scientists to solve.In this paper,In order to further improve the CO catalytic activity,we adding transition metals and noble metals in CeO₂.We have prepared Au/CeO₂ nanorods and nanobundles,Au/CeO₂nanospheres and 0¹5%CuCeO₂ composite oxides by solvothermal method.The catalysts were characterized by XRD,SEM,TEM,BET,XPS and other technical means.At the same time,we also tested the application of these catalysts in the oxidation of CO or the reduction of4-NP.The main contents of this paper are as follows:?1?Preparation of Au/CeO₂ nanorods and nanobundles and their catalytic properties for CO catalytic oxidation and 4-NP reductionThe precursors of Ce-BTC were prepared by solvothermal method using BTC as an organic ligand.And Au/CeO₂ nanorods and nanobundles were obtained by calcining at high temperature and loading Au.To demonstrate their functional superiority,the as-prepared Au/CeO₂ nanocatalysts were utilized for CO oxidation and 4-nitrophenol reduction.Through the 4-NP reduction performance test,we found that the activity of Au/CeO₂ nanorods was higher than that of Au/CeO₂ nanobundles.The CO catalytic oxidation showed that the catalytic activity of Au/CeO₂ nanorods(T₅₀=50 ^oC)was higher than that of Au/CeO₂nanobundles(T₅₀=78 ^oC),and pure CeO₂.This is mainly due to the synergistic effect of Au and CeO₂,and the oxygen vacancy content of the Au/CeO₂ nanorods is higher than that of the Au/CeO₂ nanobundles,which makes the catalytic performance of Au/CeO₂ nanorods better.In addition,Au/CeO₂ nanorods showed high stability in CO oxidation,and the catalytic activity remained stable for 10 h at 140 ^oC.?2?Preparation of Au/Ce O₂ nanospheres and its application in CO catalytic oxidationAu/CeO₂ nanospheres have been designed and synthesized through solvothermal method with 3,5-Pyridinedicarboxylic acid?3,5-PDC?as organic ligands,which involves two steps including the synthesis of CeO₂ nanospheres from the precursors of CePDC MOFs by thermal annealing,and the Au loading via the impregnation method.The effects of calcination time on the structure of CeO₂ nanospheres were studied,and we also tested the CO catalytic oxidation performance of Au/CeO₂ nanospheres.It was found that the catalytic performance of Ce O₂ as carrier load Au was best after calcined 5 h,which may be attributed to the reason that CeO₂-5h was a porous hollow sphere,and that the conversion rate of CO was 50%when Au/CeO₂-5h was 40 ^oC.?3?Preparation of Cu doped CeO₂ nanomaterials and its application in catalytic oxidation of CO0¹5%CuCeO₂ microspheres have been synthetized through a simple solvothermal synthesis followed by annealing treatment using carbon spheres as template.The catalytic effects of Cu doped with different contents on CO oxidation were investigated.It is found that5%CuCeO₂ has the best catalytic activity.CO is completely oxidized at 140 ^oC,and 5%CuCeO₂ has good stability at high temperature.When the Au nanoparticles were loaded on 5%CuCeO₂ by impregnation,the catalytic performance of Au/5%CuCeO₂ was further improved,which was mainly the synergistic effect between Au and 5%CuCeO₂.Based on the MOFs and carbon sphere as the template to synthesize the CeO₂ precursors,we designed and synthesized three different structures of CeO₂ nanomaterials,which showed good catalytic oxidation performance of CO,and provided a new way for the development of the purification of automobile exhaust.