Effects Of Samarium Exchanged On Cu/SSZ-13 Zeolite For Catalytic Removal Of NO_x In Vehicle Exhaust

NO_x（NO and NO₂）emitted of diesel exhaust has polluted the environment and endangered human health seriously.NH₃ selective catalytic reduction technology（NH₃-SCR）was firstly proposed by Engelgard in 1957,which has excellent denitration activity and a wide denitration temperature windows.The key of this technology is choose a suitable catalysts.SSZ-13 molecular sieve catalysts have attracted extensive attention due to their wide denitration temperature window and excellent hydrothermal stability.The active metal content,the position and play a key role in widening the reaction window of the SSZ-13 molecular sieve and improving the hydrothermal stability.A suitable Si/Al ratio of SSZ-13 plays an important role on increasing denitrification activity and hydrothermal stability.At present,the active metals of SSZ-13 mainly includes Fe,Cu,and Ce.And the Sm and Ce metals both belong to the lanthanide metal,and the nitrates are all trivalent,but the research on Sm/SSZ-13 is still very rare.In this paper,the denitration activity,N₂ selectivity and hydrothermal stability of Cu-SSZ-13 samples were investigated by prepared Cu/SSZ-13molecular sieves with different Si/Al ratios.Then,the active metal Sm was introduced into the optimal Si/Al ratio Cu/SSZ-13 samples.The effects of solution exchange temperature,exchange time and solution concentration on denitration performance were investigated.The main conclusions are as follows:1)With the increasing of Si/Al ratio,the denitration activity are gradually reduced.The SA10 and SA40 samples were exchanged by different concentrations of copper solution,it can be concluded that the denitration activity of SA10 samples gradually increases with the increase of the concentration of copper solution,but the denitrification activity of SA40 samples is unchanged with the increase of the concentration of the copper solution.2)The Sm was exchanged on the Cu/SSZ-13 samples with the Si/Al ratio is8.By investigating the solution concentration,ion exchange temperature and exchange time,it can be concluded that:after adding active metal Sm in Cu/SSZ-13 molecular sieve,Sm enhances its high temperature activity.The denitrification activity of all samples decreased significantly after hydrothermal aging;As the ion exchange temperature increases,the low temperature activity does not change,but the high temperature denitration activity window is broadened.The difference in denitration activity of Sm/Cu/SSZ-13 samples prepared at different solution exchange temperatures indicates that the appropriate ion exchange temperature will enhance the effect of Sm;Different ion exchange time had little effect on denitrification activity,and the denitrification activity temperature window of C2-80T-4h-F sample was the widest,but its hydrothermal stability was the worst.3)The optimized Sm ions exchange conditions were:0.075 mol/L samarium nitrate solution exchanged at 60℃ for 4 h.