Selective catalytic reduction(SCR)is currently recognized as the most efficient and mature denitrification technology,with the catalyst being the core of this technology.Cerium tungsten composite oxide is a non vanadium SCR catalyst.In order to maintain its efficient and stable denitrification activity for a long time,it is of great significance to conduct in-depth research on its poisoning mechanism.CeWOx composite oxide denitrification catalyst was prepared by co precipitation method,and the influence of alkali metal species(Na2O and K2O)on catalytic activity was investigated.The reasons for catalyst poisoning were analyzed using N2-BET,XRD,NH3-TPD,and H2-TPR.The activity evaluation results showed that the denitrification activity of the catalyst was significantly inhibited after alkali metal poisoning,and the degree of deactivation caused by K2O was much greater than that caused by Na2O.Within the reaction temperature range of 150～400℃,the NOx conversion rate of CeWOx poisoned by 1%K2O decreased by 52%～84%compared to fresh catalyst.The N2-BET results indicate that alkali metal deposition leads to a decrease in the specific surface area of the catalyst.The XRD results indicate that the introduction of alkali metals leads to an increase in the grain size of CeO2 on the catalyst.The NH3-TPD and H2-TPR results indicate that surface doping of alkali metals can significantly suppress the surface acidity and redox performance of the catalyst.
alkali metal poisoningNH3-SCRCeWOxdeactivation mechanism
NETL
NSTL
万方数据
