Analysis of the reaction mechanism of N/S co-doped carbon-based catalysts for low-temperature NH3-SCR reduction of NOx

In this paper a series of N/S co-doped carbon-based low-temperature denitrification catalysts were prepared using thiourea and coal-based activated carbon. Tests such as BET, NH3-TPD, XPS and DRIFTS were applied to characterize the performance of the prepared catalysts. It was found that the denitrification activity of NSAC-1.2 catalyst was 2.08 times higher than that of coal-based activated carbon. The denitrification activity of all N/S co-doped carbon-based catalysts was greater than 80 % in the temperature range of 150–260 °C. The presence of N and S functional groups creates more acidic sites and oxygen vacancies on the catalyst surface, which leads to the reduction of the reaction energy barrier, the promotion of the adsorption and activation of reactants and in turn the improvement of the denitrification activity of the catalyst. N/S co-doping for N-5 and N-6 groups as well as C-SO2-C species enhancement affect the catalyst denitrification activity improvement comprehensively. The reaction mechanism of NH3-SCR process on N/S co-doped carbon based catalysts was investigated by in-situ DRIFTS.