Research On NO_x Storage Materials In Vehicle Exhaust At Low Temperatures And Removaling Mechanism

The NOx storage reduction (NSR) technology can be used to remove the NOx in the presence of excess oxygen from vehicle exhaust effectively. However, the low-temperature NOx storage capacity (NSC) of NSR catalysts have been still unsatisfactory due to the the low NO oxidation rate at relatively low temperature. In this work, the catalysts were prepared by coprecipitation methods, and the catalysts prepared of plasma treatment and without plasma treatment were donated as Ni-Al and Ni-Al-P, respectively. These catalysts have been investigated on their performance in NOx storage capability at 100℃. Two kind of catalysts perpared with different ratio of Ni / Al have been studied. These catalysts have been characterized by N2 Adsorption BET, X-ray Diffraction, Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, and in-situ Diffuse-Reflectance Infrared Fourier Transform Spectroscopy. The main results were summarized as follows:The different catalysts all showed good performance in NOx storage capability, especially the 0.3Ni-Al catalyst.The adsorption capacity had a very great degree enhancement after the plasma processing,and it indicates that plasma processing may obviously enhance the catalyst the NOx adsorption performance.Combined the curve of NSC (Nitrogen oxides Storage Reduction) to analyse, the curve of XRD were corresponding to the curve of NSC. The 1.0Ni-Al had the most significant crystal, but its adsorption capalities were low. These show a high degree of crystallization on the catalysts surface were not conducive to NOx adsorption, Namely, low nickel oxide dispersion was not conducive to NOxadsorption on the catalyst surface. There were also instructions on the adsorption role in promoting not only nickel oxide, but also nickel-aluminum acid. The good performance in storage capability of 0.3Ni-Al catalyst, further illustrates when the partial oxidation of nickel and nickelmetaaiuminate reaches a certain proportion of cases more conducive to NOx adsorption.There was no effect on pulsing corona discharge de-NO without any reagent, moreover in the corona discharge situation, the concentration of NO would be increased. The effect of propylene was better than that of NH3, and it increases the quantity of low-carbon hydrocarbons and reduces the ammonia leakage secondary pollution.