Study on Urea-SCR system basing on Pre-oxidation

To improve activity of traditional Vanadium-titanium SCR (Selective Catalytic Reduction) catalyst under low temperature condition, Pre-oxidation technology is proposed in this research. In this paper chemical reaction kinetics which includes chemical reaction mechanism, reaction rate and so on is studied, and especially chemical reaction rate equations on "Standard-SCR Reaction" and "Fast-SCR Reaction" are deduced. By the bed test of YZ4DB1-30 diesel engine, it has been found that the activity of Urea-SCR catalyst with DOC (Diesel Oxidized Catalyst) is significantly improved at low temperature. Compared with traditional SCR system, NO_x conversion efficiency of the Urea-SCR system with DOC increases linearly at temperature of 150°C~250°C. When temperature is at 150°C1, the Urea-SCR system with DOC could transform more than 25% NO_x, and the general average is more than 70% NO_x.