Controllable Construction And Catalytic Performance Of Cerium/Copper Based Nano Composite Catalytic Material

Catalysis plays a key role in most industrial processes,which using catalysts to achieve high conversions or product selectivities by reducing reactant activation energy barriers over 80%of the catalytic process.Therefore,the efficient catalysts,which are reasonable and scientific designed,are essential to improve the performance of chemical reactions.Generally,heterogeneous catalysts are consisted of metal oxide and nanoparticles,and widely used in many application fields,such as chemical industry,pollution prevention,energy technology,etc.While metal oxides not only act as support for dispersing metal nanoparticles,but also can improve the catalytic performance of the catalysts through interaction with metal nanoparticles,ie,a strong metal-support interaction?SMSI?.In this paper,we mainly prepared a series of CeO2-based and Cu-based nanocatalysts with mesoporous structures,and systematically studied the catalytic performance of these nanocatalysts for CO preferential oxidation reaction and benzyl alcohol aerobic oxidation reaction and proposed the relationship between the structure and properties of catalysts,explaining the catalytic mechanism of the nanocatalysts.In the first chapter,the research status of rare earth cerium-based nanocatalysts was systematically reviewed,and the ways to improve of catalytic performance of cerium-based catalysts were proposed.The research ideas and main research contents of this paper were proposed.In the second chapter,the CeO₂ shell was coated on the surface of SiO₂microspheres which were used as the hard template by the hydrothermal method,and the self-assembled hollow CeO₂?@CeO₂?nanoparticles with high-energy crystals were synthesized by the chemical etching with fluorine-containing ionic liquid[Bmim][BF₄]under hydrothermal conditions after removal of the SiO₂template by NaOH.The results found that the F^-ions in[Bmim][BF₄]ionic liquids play an important role in regulating the morphology and crystal surface exposure of CeO₂nanoparticles.At the same time,we also used other reagents containing fluorine?NH₄BF₄,NaBF₄ and NH₄F?as etchants to prepare hollow@CeO₂ nanospheres with different morphology.Afterwards,the highly dispersed Au nanoparticles were supported on different hollow@CeO₂ supports to obtain@CeO₂/Au nanocatalysts with different structures and morphologies.And the catalytic performance of these catalysts for benzyl alcohol aerobic oxidation was investigated.In the third chapter,the uniform size of CeO₂ microspheres were prepared by hydrothermal method,which were treated with ionic liquid[Bmim][BF₄]using hydrothermal method for different times.Then the Au-Pd nanoparticles were supported on the surface of the CeO₂ by sol-impregnation process,forming the CeO₂/Au-Pd nanocatalysts.The interactions between Au and Pd nanoparticles,Au-Pd and CeO2 were determined by detailed characterization.The catalytic performance of the CeO₂/Au-Pd nanocatalyst was evaluated by benzyl alcohol aerobic oxidation.The effect of the structure,morphology,composition,specific surface area and pore structure,noble metal loading and ratio,oxygen vacancy concentration,and surface element composition and valence states of the catalyst on catalytic performance of the CeO₂/Au-Pd nanocatalysts for benzyl alcohol aerobic oxidation were investigated.In the fourth chapter,ionic liquid[Bmim][BF₄]was used to etch Ce O₂microspheres treated with different concentrations of sulfuric acid or sodium hydroxide solution,to obtain CeO2 nanocubes exposed to high-energy crystal faces.Then,the Cu_xO clusters were deposited on the CeO₂ nanocubes by deposition precipitation method to obtain a series of CuxO/CeO2 nanocube catalysts.The catalytic performance of Cu_xO/CeO₂ nanocube catalysts was evaluated by the benzyl alcohol aerobic oxidation and CO preferential oxidation.In the fifth chapter,a series of CuO-CeO₂ nanocatalysts with finely controllable surfacestatesweresynthesizedusingCu_xCe_1-x-BTCMOFs?BTC:1,3,5-benzenetricarboxylic acid?as precursors.Then,CuxCe1-x-BTC MOFs were decomposed under high temperature to obtain the porous CuO-CeO₂ nanocatalysts,which were composed by uniformly dispersed CuO and CeO₂ nanoparticles.The catalytic performance of CuO-CeO2 nanocatalysts for the benzyl alcohol aerobic oxidation and CO-PROX reactions can be controlled by regulating the ratio between Cu and Ce and the calcination temperature of Cu_xCe_1-x-BTC.In the sixth chapter,highly dispersed octahedral Cu-BTC was prepared under mild synthesis conditions.Then,the partially Mn-substituted Cu-BTC,ie,Mn/Cu-BTC,was synthesised by using a simple solvothermal method,which still maintains the octahedral morphology.Amount of Mn substitutions in Mn/Cu-BTC precursor can be obtained by adjusting the amount of Mn source and the solvothermal reaction temperature.Subsequently,the Mn/Cu-BTC precursor was pyrolyzed at 400? to remove the organic ligands from the MOFs,forming CuMnO_x nanocatalysts with octahedral structure.The composition,structure,specific surface area,pores,surface element composition and valence of the catalysts were systematically studied,and catalytic performance of the catalysts was evaluated by benzyl alcohol aerobic oxidation and CO oxidation.