NO Reduction By Propane Over Monolithic Cordierite-based Fe/Al2O3 Catalyst: Reaction Mechanism And Effect Of H2O/SO2

The selective reduction of NO by C3H8and the sensitivity to H2O and SO2have been studied over monolithic cordierite-based Fe/Al2O3catalysts, which were prepared by the sol–gel and impregnation method. The catalysts were investigated by N2 adsorption, X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) techniques. Results showed that NO reduction was more than 90% in the absence of oxygen at 500 °C and in the presence of oxygen at 600 °C respectively. In a continues test of 12 h at 600 °C, 0.02% of SO2caused an irrecoverable decrease of NO conversion from 94% to 85% and 2.5% of H2O caused a drop of NO conversion from 86% to 56%, while NO conversion totally recovered when H2O was removed. The catalysts lost 15% of the initial activity after a hydrothermal treatment due to the agglomeration of iron oxide nanorods. Sulphidation treatment caused about a loss of 30% of the initial activity because of the deposited SO42−species. In situ study by DRIFTS indicated that coexisting H2O influenced the formation NO2 ad species and unidentate nitrate, while SO2 slightly inhibited the formation of NO2/NO3−species but promoted the formation of acetate/formate species during NO reduction by C3H8. Based on the results, a preliminary mechanism was proposed and discussed. The results may help understand the fundamental performance of monolithic cordierite-based Fe/Al2O3catalysts and provide some reference for SCR-HC catalyst design

Preparation, Characterization, And Properties Of Monolithic Fe/Al2O3/cordierite Catalysts For NO Reduction With C2H6

Monolithic cordierite-based Fe/Al2O3 catalysts were prepared using a sol-gel and impregnation method and characterized by N2 adsorption, XRD, SEM, XPS, H2-TPR, and an activity test for the reduction of NO with C2H6. The results indicated that the textural properties, surface morphology, nanorod size, crystallinity, reducibility, and NO reduction activity of the catalysts were correlated with the iron loading. The order of the C2H6-SCR activity was as follows: 5.5Fe/Al2O3/CM \u3e 3.5Fe/Al2O3/CM \u3e 8Fe/Al2O3/CM \u3e 2Fe/Al2O3/CM. High activity (97% NO conversion) was observed with 5.5 wt.% iron at 600°C in the presence of oxygen. The results indicate that the iron oxide nanorods distributed on the surface of the Al2O3 layer may act as the SCR active site. Based on in situ DRIFTS spectral analysis, O2 can act as a promoter for the formation of the NO2/NO3- species. However, the formation of -NCO species does not appear to be accelerated by O2