| NOx and soot from diesel engines exhaust were harmful to environment. Accordingly, simultaneous removal of NOx and diesel soot in the after-treatment processes had attracted great concerns. Perovskite-type and perovskite-like oxides showed high catalytic activity of simultaneous removal of NOx and soot due to the special structure.In this dissertation, a series of nickel-based ABO3 perovskite-type or A2BO4 perovskite-like mixed oxide catalysts were synthesized via the citric acid complexation. Moreover the catalysts were modified by doping other elements at A or B site. Furthermore co-doped at A and B sites perovskite-like catalysts were prepared based on the central composite design combined with response surface methodology for the first time. Many techniques, such as X-ray diffraction (XRD), H2 temperature programmed reduction (H2-TPR), O2 temperature programmed desorption (O2-TPD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) were employed for catalyst characterization. The catalytic activities for simultaneous removal of NOx and soot were evaluated using a technique of temperature programmed reaction under the modeled diesel engine exhaust circumstance. The effects of reaction conditions, including concentrations of NO or O2 and different contact modes, on catalytic performance were investigated over optimal catalyst obtained from response surface methodology.La1-xCexNiO3 (0≤x≤0.05) catalysts showed the perovskite structure corresponding to a rhombohedral system. The proper substitution amount of Ce was x < 0.05 to form the uniform perovskite structure. The doping of Ce improved the catalytic performance. The catalyst showed the highest activity for x = 0.03. The maximum conversion of nitrogen oxide to nitrogen was 11.8% and the ignition temperature decreased to 314°C.La2-xSrxNiO4 (0≤x≤1.0) catalysts indicated the tetragonal K2NiF4-type structure. The amount of Ni2+, oxygen vacancy and mobility of lattice oxygen played an important part in the catalytic performance. The highest activity was observed for the catalyst at x = 0.5. The maximum conversion of nitrogen oxide to nitrogen and the ignition temperature were 20.6% and 251°C, respectively.La2Ni1-xCuxO4 (0≤x≤1.0) catalysts possessed the orthorhombic K2NiF4-type structure. The doping of Cu led to the enhancement of orthorhombic distortion and the decrement of capability to accommodate non-stoichiometric oxygen. The La2Ni0.4Cu0.6O4 catalyst showed the highest activity. The maximum conversion of nitrogen oxide to nitrogen and the ignition temperature were 15.6% and 246°C, respectively.A novel kind of double doped La2-xSrxNi1-yCuyO4 (0 < x < 1.0, 0 < y < 1.0) perovskite-like catalysts were synthesized based on the central composite design combined with response surface methodology. The mathematical relationships between the response Y (XNO max and Tig) and two variables namely the amount of Sr (X1) and the amount of Cu (X2) were estimated by the nonlinear polynomial model through MINITAB statistical software. The optimization results for X1 and X2 obtained from MINITAB RESPONSE OPTIMIZATION PROGRAMME were 0.92 and 0.32 respectively. The performance of the catalyst prepared based on the optimal composition was investigated. XNO max and Tig were 27.7% and 239°C respectively, which fitted the prediction well. In this case, over the optimized catalyst, the catalytic performance increased with increasing NO inlet concentration when keeping the O2 concentration constant. However the catalytic activity decreased not only with the increment of O2 inlet concentration holding the NO concentration unchanged, but also with loose contact between catalyst and soot. Under the simulated real diesel engine exhaust ratio of NO and O2 and loose contact mode, the performance of optimized catalyst for XNO max and Tig were 20.8% and 222°C, respectively.
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