3DOM Al₂O₃ Supported The Pt-metal Oxide Catalysts Synthese, Characterization And Catalytic Performance For Soot Combustion

In recent years,a series of haze weather occur in the majority regions of our country.It is a serious threat to the environment and human health.The soot particles derived from motor vehicle emission is one of the main sources,therefore,the diesel emission standard was made more and more strict in many country.Catalytic purification technology is the most effective and thorough way to eliminate the diesel soot particles,and its core technology is the development of highly efficient catalyst.Soot combustion is typical of solid-solid-gas heterogenous catalysis reaction,and soot oxidation is also sensitive to the structure of catalysts.Thus,the catalytic performance is changed by adjusting the catalyst morphology structure and composition,and its not only have the research significance for heterogeneous catalysis reaction,but also for environmental protection.In this paper,the study and design of a new type catalyst is mainly concentrated in two aspects:one is to improve the performance of material,the catalyst is preparated into three-dimensional ordered macroporous structure,which will improve the contact performance between soot and catalyst by using its tunnel effect;the other is adjust the composition of catalyst,which will improve the catalytic performance for oxygen activation.In this thesis,we select Al₂O₃ as the carrier,and the core-shell structure nanoparticles of the noble metal-metal oxide supported on the surface of 3DOM Al₂O₃,which improves the reaction rate for soot oxidation.Using XRD,BET,SEM,TEM,ICP and H₂-TPR characterize the physicochemical property of catalysts,and combined with the kinetics study the relationship between morphology structure and catalytic performance.Main contents and conclusions are as following:?1?3DOM Al₂O₃ carrier was successfully synthesised by the preparation of the PMMA microspheres and colloidal crystal template method.The 3DOM Al₂O₃ have regular pore structure,and also found that a lot of spherical voids exist in the 3DOM catalysts structure.The pore size is more or less 320 nm,and it also maintain regular channel structure.?2?3DOM Al₂O₃ supported Pt-TMO?Mn₂O₃,Fe₂O₃,Co₃O₄,NiO,CuO?core-shell structure catalysts were prepared via GBMR-P method.The average particle size of the nanoparticles was 3.8 to 5.5 nm and uniform distribution.With the increasing of metal oxide,nanoparticle size will enlarge.3DOM Pt@Co₃O₄/Al₂O₃ catalyst shows the highest catalytic activity for soot combustion.(T₁₀,T₅₀,T₉₀ and S^m_CO2 was 280,341,382?,98.29%,respectively)?3?By changing the species and dosage of transition metal oxides,the core-shell structure nano-catalysts showed high stability.It produced a positive effect for catalytic performance.The activation energy Ea of the catalysts?46⁶8 KJ/mol?were lower than Pt/Al₂O₃?94 KJ/mol?catalyst.3DOM Pt@TMO/Al₂O₃ has better reactive oxygen species.?4?Using GBMR-D method to prepare the 3DOM Pt@KO_x/Al₂O₃-x catalysts,and it also shows high activity.The results show that the strong interaction between Pt and alkali metal oxide make the T₁₀,T₅₀,T₉₀ increased and the S^m_CO2 reduced.Alkali metal catalyst had more excellent low temperature performance(much lower T₁₀),because it has much higher activity at low temperature.?5?By using XRD,BET,SEM and TEM characterized the physicochemical property of catalysts.The reactive oxygen species on the surface of the catalyst were discussed by H₂-TPR.Research results show that core-shell structure have rich active sites,the strong activation ability of small molecules,promote the indirect oxidation of soot.The strong interaction between Pt and metal oxide plays an important role for the stability of the catalysts,and also has decisive role for soot combustion.