Experimental Study On Synergistic Removal Of Soot And NO_X In Diesel Engine

In recent years,diesel engines have been widely used due to their strong dynamics and good fuel economy.However,soot particles and NO_X in the exhaust gas are the main air pollutants,which have caused great impact on the ecological environment and human health.The diesel particulate filter and selective catalytic reduction technology are used in the diesel engine to remove soot particles and NO_X in the exhaust gas respectively.However,the diesel particulate filter needs periodic regeneration,and the selective catalytic reduction technology needs to consume urea,which cost a lot and has complicated structure.Achieving the synergistic removal of soot and NOx is a simple and efficient method.This paper will use CuO-ZSM-5 catalyst for the simultaneous removal of soot and NOx.In this paper,the effects of simultaneous removal of soot and NO_X under different reaction conditions,including reaction temperature,the physical structure of carbon and catalyst dispersion,were compared.The adsorption and catalytic conversion of NO_X on the catalyst surface were studied,and the role of soot and oxygen in the synergistic removal of soot and NO_X was studied.The synergistic removal of soot and NO_X under different reaction conditions showed that activated carbon and soot could react with NO_X under the condition of CuO-ZSM-5 as catalyst to achieve synergistic removal of soot and NOx.Temperature has a great influence on the synergistic removal of soot and NO_X.The highest removal efficiency of NO_X is about11%at around 400°C,but the catalyst has been deactivated when the temperature continues to rise to 500°C;CuO can not be used alone as a catalyst to promote soot combustion and NO_X reduction,loading CuO onto ZSM-5 to make CuO-ZSM-5 catalyst can greatly improve the removal efficiency of soot and NOx.When CuO-ZSM-5 catalyst is used,NO can be oxidized to NO₂ at 200°C,and the NO oxidation rate first rises and then decreases with increasing temperature,and the rate of NO oxidation to NO₂ decreases significantly when the temperature reaches 450°C or higher.NO_X can be adsorbed on the surface of the catalyst at 300°C or below.When the temperature reaches 400°C,the removal path of NO_X is mainly catalytic reduction;in the case of a certain catalyst volume,the increase of the proportion of soot effectively reduces the amount of NO oxidation.NO_X cannot be catalytically reduced by soot under anaerobic conditions...