Co-doping Of Silver And Cobalt LaMnO₃ And Low-temperature Plasma Synergistic Catalytic Performance Of Soot

Soot particulate matter is one of the main pollutants emitted by diesel vehicle exhaust,and it is also a major source of urban pollution that endangers the environment and human health.However,the currently developed catalyst for removing soot has problems such as poor low-temperature activity,Low-temperature plasma technology has the advantage of activating reaction gas components at lower temperatures and promoting the occurrence of chemical reactions,which makes this technology attract wide attention in the field of catalysis,However,the plasma itself has problems such as high energy consumption and low selectivity.Therefore,in order to improve the low-temperature catalytic activity of the catalyst and reduce the energy consumption of the cold plasma,a combination of low-temperature plasma and the catalyst is used to act on the reaction system.In this paper,a series of La_1-xAg_xMn_1-yCo_yO₃ perovskite composite oxides doped with Ag and Co at the A and B sites were prepared by the sol-gel method and citric acid as the complexing agent.The effects of Co doping amount when Co doping on the B site alone,Ag doping amount when doping on A site alone and the doping amount change when A and B sites are doped at the same time and the effect of plasma co-catalyzed soot oxidation are studied.Combine XRD,IR,H₂-TPR,O₂-TPD,XPS and other characterization methods to characterize the prepared catalyst,and analyze the synergistic catalytic effect of plasma and catalyst.The main conclusions are as follows:（1）For the La Mn_1-yCo_yO₃ perovskite catalyst doped with only B-site Co,under the conditions of 200℃and 10 W input power,the removal efficiency of PM in the coordinated catalytic reaction of plasma and La Mn O₃ is 13%,while the introduction of Co ions The catalytic effect has not been improved.（2）For the La_1-xAg_xMn O₃ perovskite catalyst doped with only Ag at the A site,the introduction of Ag can significantly improve the synergistic catalytic effect.Among them,the efficiency of La_0.5Ag_0.5Mn O₃ and plasma synergistic catalytic removal of PM is 68%,and the selectivity is 92%.Compared with La Mn O₃,the conversion rate is increased by 55%,which may be caused by the activation of Ag nanoparticles and the oxygen vacancies near the Ag nanoparticles and the Ag⁺in the crystal lattice on the adsorption of oxygen in the plasma discharge region.（3）For Ag and Co co-doped La_1-xAg_xMn_1-yCo_yO₃ perovskite catalyst.The solubility of Ag⁺ions at site A of La Mn O₃ is limited by Co³⁺ions at site B.The increase of Co³⁺ions at site B will cause excess Ag⁺to be eluted from the crystal lattice.The content of Ag nanoparticles on the surface of the perovskite increases with the increase of Co doping at the B site.In the study on the performance of low-temperature plasma synergistic LA_xMC_y catalytic oxidation soot combustion,when the Ag feed ratio is 0.2,the synergistic catalytic effect of LA₂MC₂ and plasma is the best,Xc and S_CO2 are 63%and 90%,respectively,almost reaching the same level as La_0.5Ag_0.5Mn O₃ similar catalytic effect.