N-Doped FeCo/ASC catalysts for NOx reduction by CO in a simulated rotary reactor

Abstract

Herein, nitrogen-doped activated semi-coke (ASC)-supported ferrum cobalt-co-impregnated catalysts (FeCo/N-ASC) were prepared and tested for deNO_x in a simulated rotary reactor. The experimental results showed that FeCo/N-ASC-3 was an optimal catalyst for the adsorption and removal of NO_x, and the NO_x conversion could reach 99.1% at the temperature of 300 °C. The physico-chemical properties of FeCo/ASC and FeCo/N-ASC catalysts were characterized by Brunauer–Emmett–Teller measurements (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance Fourier transform spectroscopy (DRIFTS). The BET and XPS spectra results revealed that the surface area and volume of micropores and nitrogen-containing functional groups, especially pyridinic nitrogen (N-6) and pyrrolic nitrogen (N-5), could be improved by nitrogen doping. Moreover, the valence state of the metal ions on the catalyst surface increased after N-doping. However, different nitrogen doping processes could lead to different crystalline structures and crystallinities, which could affect the rapid NO_x adsorption and reduction performance of the catalysts at different temperatures. In the simulated rotary reactor, FeCo/N-ASC-3 showed better NO removal ability than other catalysts and exhibited high NO_x reduction efficiency at the high temperature of 300 °C. Based on the catalytic activity of the proposed catalysts in the dynamic NO_x adsorption–reduction process and results of the analysis of different surface characteristics of the catalysts, the possible deNO_x mechanism of N-doped ASC catalysts was proposed.