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 deNOx in a simulated rotary reactor. The experimental results showed that FeCo/N-ASC-3 was an optimal catalyst for the adsorption and removal of NOx, and the NOx 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 NOx 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 NOx reduction efficiency at the high temperature of 300 °C. Based on the catalytic activity of the proposed catalysts in the dynamic NOx adsorption–reduction process and results of the analysis of different surface characteristics of the catalysts, the possible deNOx mechanism of N-doped ASC catalysts was proposed.