No Selective Catalytic Reduction Of The Experimental Study

Selective catalytic reduction (SCR) of NO with hydrocarbon has become one of important projects. To find an efficient catalyst is of great importance for the research. In this paper, we have studied the Cu/Al₂O₃ catalysts with Al₂O₃ as support. The activity of Cu/Al₂O₃ catalysts had evaluated by fixed-bed micro-reactor equipment. We systematically investigated the influences of the different making methods ,different calcinations temperatures, different Cu loading, various oxygen concentration, reaction temperatures ,different NO/C₃H₆ ratio and so on. We analyzed the physical properties, crystal structures and surface structures of the catalysts by SEM , BET , XRD. In addition, we introduced the kinetic of NO catalytic selective reduction on prepared catalysts.The results showed that Cu/Al₂O₃ prepared by sol-gel+impregnation has the optimal activity for NO reduction. When Cu loading is 15wt%, the catalyst has the optimal activity. Its NO conversion rate can reach 57% and C3H6 conversion rate can reach 80% when the reaction temperature is 300℃. Compared with the same kind of oxide catalysts, it has obvious advantages of activity in low-temperature reaction condition. The research of calcination temperature on the NO reaction activity showed that the fitting temperature was 750℃.XRD illustrated that CuAl₂O₄ are the active species on Cu/Al₂O₃ catalysts. Through the experiment research of reaction conditions ,we found the catalysts had the most activity when the reaction temperature was between 300℃ and 350℃ and oxygen concentration was 5% and NO/C₃H₆ ratio was 1:1.The effect of the addition of La or Mn on Cu/Al₂O₃ catalysts wasalso researched. It's results showed that addition of La or Mn couldn't improve the activity of catalysts and make it's activity decreased to some extent. Moreover , with the La or Mn loading increasing, the extend was enlarged. Through BET study, we found the surface areas of the Cu/Al₂O₃ with La or Mn loading declined. The addition of 1% Ce would enhance the high-temperture activity of catalysts on NO conversion. But the addition of 5% Ce is opposite. The addition of Co would improve high-temperature activity and decline low-temperature activity. All in all, we still couldn't find the proper second ingredient which cooperated with Cu. The work in point need continue.It will ground a theoretical study in the follow- up research through establishing one of the NO selective catalytic reduction kinetic models. Because of the restricts of researching conditions and time, we couldn't work out the parameters in the kinetic model.Compared with the same kind of catalysts, 15wt% C11/Al₂O₃ had the obvious advantages of high activity at low temperature and low expenditure. We can broaden the catalytic activity window through the combination between the high activity catalysts at low temperature and the high activity catalysts at high temperature.