A Kinetic Study of SCR of NOx by NH_3 over γ Fe_2O_3 Nano-catalyst

摘要

In this study, we focus on the SCR reaction mechanism over γ Fe_2O_3 nano-catalyst. The kinetic parameters of the SCR reaction on γ Fe_2O_3 nano-catalyst were investigated in a differential reactor. Through kinetic research, it can be found that the reaction orders are 0.78-0.93, 0 and 0.9-0.11, respectively, for NO, NH_3 and O_2. The observed activation energy is 57.3kJ/mol. Combined with DRIFTS study, it can be concluded that increasing NH_3 concentration could not increase the rate of NO conversion because NH_3 could be strong adsorbed on the catalyst surface and the adsorption sites could be saturated by NH3 easily at low temperature, adsorbed NO_2 and nitrite species could be generated on the catalyst surface. The SCR reactbn is mainly followed L-H mechanism at the temperature below 270°C, and E-R mechanism at the temperature above 270 °C.