The Synthesis And Catalytic Activity Of Three-dimensionally Ordered Macroporous-mesoporous Ce_1-xZr_xO₂ Solid Solution For Soot Combustion

Soot particles emitted from diesel-powered vehicles are one of the biggest inducements for hazy weather,therefore the elimination of soot is of great importance in the protection of the environment and human health.As a typical structural-sensitive heterogeneous catalytic reaction,soot catalytic combustion has been regarded as the most effective way to remove soot radically,thus the morphology of the catalyst plays a predominant role in soot combustion reaction rate.The three-dimensionally ordered macroporous（3DOM）structure can bring the soot particles into the catalyst’s inner space,and the ordered mesoporous（OM）structure would enlarge the specific area of the catalyst and enhance the activation of small molecules,so the main purpose of this thesis is to initiate the synthesis of three-dimensionally ordered macroporous-mesoporous（3DOMM）Ce_1-XZr_XO₂ to combine the advantages of both 3DOM and OM catalyst.OM Ce0.5Zr0.5O₂ catalysts are synthesized by several approaches and 3DOMM Ce_1-XZr_XO₂ catalysts are also successfully synthesized in the work of this thesis.Characterizations,such as X-ray diffraction,BET surface analysis,Scanning electron microscope,Transmission electron microscope and H2-TPR,are used to test the physicochemical properties of the as-prepared catalysts.Besides,the catalytic performances are investigated through a fixed bed microreactor.The main conclusions are as follows:（1）Evaperation-induced Interfacial Self-Assembly（EISA）and Nano Impregnation are both feasible approaches to synthesize OM Ce0.5Zr0.5O₂.P123 and F127 are both great mesoporous templates as EISA is applying into practice,while the optimal concentration is 1 g P123 or F127/20 m L ethanol.（2）EISA and colloidal crystal template method can be combined organically to initiate the synthesis of 3DOMM Ce_1-XZr_XO₂ in which the macropores are three-dimensionally ordered type and mesopores are two-dimensionally ordered cubic type.（3）All the surface areas of as-prepared Ce_1-XZr_XO₂ are larger than 70 m2·g-1,which increases by 40% compared with that of 3DOM Ce_1-XZr_XO₂.Besides,the wall of themacropore is gradually widening as the proportion of Ce increasing.（4）Compared with 3DOM Ce_1-XZr_XO₂,3DOMM Ce_1-XZr_XO₂ has more abundant active sites.The ordered mesopores on the macroporous walls promote the activation ability of small molecules,such like O₂,CO and NOX,which largely enhances the indirect oxidation of soot.The advantages of this hierarchical structure are reflected in the lower T10 and greater s_CO2^m of the 3DOMM Ce_1-XZr_XO₂ catalyst.