Research Progress On The Electro-assisted Catalytic Reduction Technology Of NO

Nitrogen oxides (NOx) discharged from power plants, coal fired boilers, industrial boilers, and automobiles, which can result in acid rain, photochemical smog, and ozone depletion and cause harm to respiratory system. Therefore, an increasing number of the research teams pay more attention to the economical and efficient approach to NO removal. By now the main technologies include selective catalytic reduction (SCR), selective catalytic oxidation (SCO) and catalytic decomposition. Selective catalytic reduction (SCR) is the most widely concerned technology for the DeNOx because that had lower second pollution and many experiences in industrial applications, but there are some problems in operating temperature, causticity and so on.This paper presents that to use the method of Electric-Assisted catalysis for catalytic reduction NOx. The supported metal catalyst was prepared by the simple and easy controlled impregnation method and the unsupported metal catalyst was prepared by low temperature solid method. Electric-Assisted catalysis reactor is designed and optimized which is a physical method could further reduce the operating temperature, the effect of adding voltage for NO reduction is carried out, and the removal efficiency are proven.Firstly, we filter the different catalyst carrier to match Electric-Assisted catalysis reactor in this study. By comparison of the NO reduction changes before and after applying voltage, the little effect of voltage on the non-conductive supported metal catalyst and unsupported metal catalyst is analyzed. For a mixture of non-conductive supported metal catalyst and conductive coconut shell activated carbon, NO reduction increased by over5%after applying5V. The highest enhancement of NO reduction for metal supported coconut shell activated carbon reach about35%after applying5V. The results indicate, the electrical and heat conductivity are the key factors affecting NO reduction in Electric-Assisted catalysis system.By considering coconut shell activated carbon as catalyst supported materials, the effect active component on catalyst is carried out, and the order is15wt%CuO/AC>15wt%Fe2O3/AC>15wt%Mn2O3/AC>15wt%NiO/AC. It is concluded that the difference of reaction temperature or conductivity of active component is the main factor resulting to this result.The Cu supported coconut shell activated carbon can be used to further study the reaction mechanism in Electric-Assisted catalysis system. This study mainly discusses the enhancement of NO reduction influenced by voltage on loading amount of active components, mash and pretreatment for activated carbon. Before applying5V, with increasing copper loadings, catalytic activity increases initially, and then decreases. After applying5V, the enhancement of NO reduction by15wt%CuO/AC is highest, which results from the slightly increasing specific surface area as suggested by BET. Because of this, the aggregation of copper species contact with the gases sufficiently. Additionally, the smaller particles provide the smaller space led to higher electrical and heat conductivity, but the mesh of catalyst should be controlled appropriately to prevent its weight loss and burned loss. Then, the more oxygen groups have, after pretreatment, the more obvious effect of voltage becomes. The free electron speeds up this catalytic reaction of the NO transfer to NO2. The best and more stable catalyst is15wt%CuO/AC-N2which is filtered by the above process of selection.Finally, the effect of voltage size, O2content and H2O in Electric-Assisted catalysis system are analyzed. The results showed that the catalyst after applying above1OV shows the higher activity, with above90%NO reduction at75℃, but the loss on ignition of activated carbon catalysts would be higher in short time and current would reach above1A at the same time. So we chose5V as rare experimental adding-voltage. By applying5V, catalysts still keeping high activity, and N2selectivity could attach to99%. We deduce that oxygen content is not the critical factor in this novel electro-assist catalytic reduction of NO, which is different from the oxygen groups in catalysts after wet pretreatment. The enhancement of NO reduction after applying5V decreased by20%in the presence of high H2O, then the voltage lost the value of existence for40min. To solve this problem, several suggestions for optimizing the design of Electric-Assisted catalysis reactor in practical use or improving the catalyst should be brought up.