Experimental Study On The NO_x Adsorption Performance Of Copper-based NSR Catalyst Under Low Temperature Environment

The emission of nitrogen oxides from automobile exhaust is the main air pollution nowadays.Faced with stringent NOx emission requirements,it has become urgent to explore and discover a highly efficient and environmentally friendly DeNOx catalyst.Among the currently available technologies,nitrogen oxide storage and reduction technology?NSR?has been considered as the most promising DeNOx technology.However,traditional NSR catalysts use a large amount of precious metals,making the cost high and lacking economic benefits.Therefore,further study is needed on how to reduce the use of precious metals and improve the performance of NSR catalysts.In this paper,composite catalysts were prepared by sol-gel method.In order to reduce the use of precious metals,this study used the more popular transition metal-Cu as an active component.CeO₂ component was added to improve the low temperature performance of NSR catalysts.Considering the interactions between the components,the values of each parameter in the preparation process are adjusted,the catalyst synthesis process is improved.Then,the structure and low temperature adsorption performance of copper based NSR catalyst would be investigated through the self-constructed simulated gas platform and methods such as XRD,BET,SEM.The main conclusions can be summarized as follows:?1?Although Cu-Ce catalysts were synthesized under different pH conditions,they show a monofilament-like structure.The specific surface area and NO oxidation performance of catalysts are also similar.However,the dispersion of the active components on the catalysts is different.In general,under acidic conditions,the pore size of the catalyst is more uniform,and the performance of the catalyst is superior to that of others.?2?When Cu-Ce catalysts were calcined at different temperatures,there are significant differences in its structure and performance.Among them,the catalyst calcined at 600°C has the most uniform structure and the best NO oxidation ability.When calcined below this temperature,the precursor is incompletely decomposed.While calcined at high temperatures,the crystallinity of the components in the catalyst is increased and the interaction between components is poor.Therefore,the performances of these catalysts are inferior to that of the calcined catalyst at600?.?3?The presence of storage components has a great influence on catalyst performance.Among different ratios of xBCC,low-loaded Ba will preferentially react with Cu to form BaCuO_2.5;while at high loads,Ba will also react with Ce.The adsorption performance of these two forms of storage components is lower than that of BaCO₃.The content of BaCO₃ in 1BCC catalyst is the most,so the NO oxidation performance and the NOx storage performance of it are better than other catalysts.?4?The doping of the zirconium component is beneficial to the dispersion of the active components in the BaCuCe_2-xZr_x catalyst.When the doping is performed with a stoichiometric number of 0.2,the structure of the catalyst is the most uniform,and the adsorption performance of the catalyst is the best.However,when the doping is carried out at a stoichiometric number of0.3,the adsorption performance of the catalyst is reduced.This is because the zirconium reacts with the barium and cerium to form Ba((Ce_0.8Zr_0.2)O₃),so its adsorption performance is lower than other catalysts.