| With the superior properties of power and fuel efficiency compared with gasoline spark ignited cars, diesel powered cars have been widely used in Europe for many years. With the economic prosperity and environmental protection, in China, diesel car have been attracting great interest, while that leads to atmosphere pollution related to diesel car.To eliminate soluble organic fraction, HC and CO in the exhaust of light diesel car, we have systematically researched in three respects:(1) the effect of Ce/Zr mole ratio on the structure and catalytic oxidation performance of Ceria-Zirconias and their Pt loaded catalysts;(2) then, we have researched the catalytic oxidation performance of different kind of support and their Pt loaded catalysts;(3) further, we have researched the catalytic oxidation performance of triple-mixed supports and their Pt loaded catalysts. In the present dissertation, we used X-ray powder diffraction (XRD), N2adsorption/desorption, oxygen storage complete capacity (OSCC), temperature-programmed reduction (H2-TPR), in situ DRIFT and catalytic activity test techniques to study the physical and chemical properties of all supports and catalysts. By carefully character, analyse and test, some specific conclusions are drawn frorm this work as follows:1. Ceria-Zirconia mixed oxides which were synthesised by co-precipitation route and alcohol-supercritical drying methods have cylindrical tubular pore structure and fair size BET surface area. The addition of proper amount of Zr makes better migration of bulk oxygen to the surface, bigger oxygen storage/release capacity and better redox performance of Ceria-Zirconia mixed oxides and their Pt only loaded catalysts. Among Ceria-Zirconia mixed oxides, C1Z1have biggest BET surface area (112.3m2/g), best redox performance and biggest oxygen storage/release capacity (433.6μmolO2/g).2. C1Z1has high catalytic oxidation performance on SOF, big average pore size, BET surface area, oxygen storage/release capacity and high redox performance of Ceria-Zirconia mixed oxide are beneficial to the catalytic oxidation of SOF. The average pore size of Ceria-Zirconia mixed oxides has shunk after Pt was loaded on, that lead the ignition temperature of SOF on Pt/CZs increase compared with SOF on CZs. The ignition temperature of SOF on Pt/C1Z1is lower among Pt/CZs. Moreover, Pt/C1Z1has high catalytic oxidation performance on HC/CO mixed gas.3. The catalytic oxidation performance of SOF on different supports and their Pt only loaded catalysts is related to their redox performance, oxygen storage/release capacity and average pore size, the catalytic oxidation performance order of SOF is Pt/C2Z1> Pt/Hβ> Pt/HZSM-5> Pt/Al2O3> Pt/SBA-15> Pt/USY; The catalytic oxidation performance order of CO is Pt/HZSM-5> Pt/H(3> Pt/USY> Pt/SBA-15> Pt/Al2O3> Pt/C2Z1; The catalytic oxidation performance order of HC is Pt/USY> Pt/C2Z1> Pt/SBA-15> Pt/Hβ> Pt/HZSM-5> Pt/Al2O3.4. There is strong synergism between different support components of ACZZ and/or ACZβ, ACZZ and ACZβ have better catalytic performance on oxidation of SOF than corresponding pure supports. The Pt/ACZZ-JY and Pt/ACZβ-JY catalysts which were prepared by Pt loading firstly, then mixed by grinding have better catalystic activity on the oxidation of SOF, HC/CO than Pt/ACZZ-YJ and Pt/ACZβ-YJ catalysts which were prepared by mixing firstly and then Pt loading. Zeolites which have high BET surface area are beneficial to Pt dispersion, and that is contributed to the catalytic oxidation of CO, HC. For Pt/ACZZ-YJ and Pt/ACZβ-YJ catalysts, there is strong synergism between Pt and CZ support, that is beneficial to Pt dispersion on the surface of CZ, their catalytic performances on oxidation of CO and HC are similar to Pt/CZ catalysts. |
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