The Preparation And Activity Evaluation Of Catalytic Ceramic Filter For DeNO_x Reaction

Catalytic filter for DeNOx reaction composed of practical ceramic filter and catalytic active component enables simultaneous removal of dusts and NOx and therefore are of great potential for industrial application in the cleaning of flue gas from mid and mini-scale boiler in China.Under operation,dusts in flue gas are removed by the exterior fine filtering membrane of a catalytic filter and the NOx is catalytically converted to N2 over the active components coated or grown on its interior surface.In this work,the catalytic ceramic filters with Cu-LDHs based and V2O5-based catalyst were prepared by in-situ growth method and coating method,respectively,and their catalytic activity and resistance to steam and SO2 poisoning were also evaluated for NH3-SCR reaction.The Cu-based catalysts derived from LDHs precursor with different promoters(Co,Ni,Zn,Mg)were synthesized.The results showed that Zn is the most suitable promoter and the(CuxZny)2Al-MMO sample with Cu/Zn ratio of 2 exhibited the maximum NOx conversion of 75% at 240?.The characterization(TEM and H2-N2 O titration)revealed that the addition of Zn will improve the dispersion and exposed surface atoms CuO.The H2-TPR results further demonstrate that the added Zn species will facilitate the reducibility of CuO species at low temperature.At last,in-situ growth of Cu-Zn-Al-LDHs on a practical ceramic filter for DeNOx reaction was carried out and the resulted catalytic filter was evaluated for NH3-SCR reaction at filtration velocity of 1 Ncm/s and NH3/NO=1 at standard conditons.It exhibited that the maximum NO conversion of 93%,pressure drop was lower than 550 Pa and strong bonding strength between catalyst and filter.Then,in order to develop a catalytic filter used in coal combustion flue gas,the V2O5-WO3/TiO2 based catalytic filters with high catalytic activity for DeNOx reaction at moderate temperatures were successfully prepared.After the optimization of preparation methods and catalyst slurry recipes,the correlation among the solid content of slurries,catalyst loading and catalytic performance has been researched.The results show that the catalytic filter with 4.2 wt.% catalyst loading was obtained by being immersed a practical cordierite ceramic filter into the 10 wt.%(TiO2)aqueous catalyst slurry under vacuum condition,followed by drying and calcination process.The slurry was composed of metatitanic acid,ammonium metavanadate and ammonium metatungstate with mass ratios at V2O5/TiO2 = 0.1 and WO3/TiO2 = 0.08.The resulting catalytic filter was evaluated for NH3-SCR reaction at filtration velocity of 1 Ncm/s and NH3/NO=1 at standard conditons.It exhibited that the NO conversion rate was beyond 90%,N2 O escape is less than 25 ppm and pressure drop was lower than 650 Pa at the temperature of 250?350?.The catalytic filter also showed a excellent performance for resistance to steam and SO2 poisoning,which meets well the request of industrial application.