The Research On NO_x Adsorbent From Diesel Engine

Nitrogen oxides discharged by diesel engine was one of main factors of air pollution,not only can cause ozone,photochemical smog and acid rain,but also damage people's health.In this work,we carried out series of studies of high performance adsorbents for the NO_x discharged by diesel engine.First,the adsorption activity and adsorption isotherms of 10¹6 mesh coconut shell charcoal?16²0 mesh coconut shell charcoal?PK1560 coal char and PK3060coal char were measured.Based on the principle of high adsorption capacity,we chose 16²0 mesh coconut shell charcoal as the best material to be modified.Then,different concentrations of Na₂CO₃?KOH?K₂CO₃ and KNO₃ were used to modify 16²0 mesh coconut shell charcoal.Compared with activated carbon modified by Na₂CO₃,the adsorption capacity of activated carbon pretreated by KOH and then impregnated with Na₂CO₃ was significantly increased.Compared with activated carbon modified by KOH and K₂CO₃,porosity and specific surface area of activated carbon modified by KNO₃ was little change due to KNO₃ did not have activation effect.The adsorption capacity of activated carbon modified by KNO₃ was increased significantly,because the potassium group can promote adsorption to the NO.The next,Co?NO₃?₂ was used to modify the activated carbon.The research results showed that the adsorption efficiency of the activated carbon was the best one which can last 80 min remaining above 90%when the impregnating solution concentration was 0.3 mol/L.The higher of the temperature was,the lower the adsorption efficiency of activated carbon could be.While the activated carbon modified with 0.3 mol/L Co?NO₃?₂ had a higher efficiency which could remain 50min above 90%at 200?.According to the analysis of SEM and FTIR,Cobalt oxide was generated on the surface and pore of activated carbon,accelerating catalytic oxidation from NO to NO₂ and then adsorption.At last,after the regeneration of the activated carbon modified with 0.3 mol/L Co?NO₃?₂,the adsorption efficiency can last 60 min remaining above 90%,the regenerative effect was good,which can make the sustainable regeneration.