Abstract
This study addresses soot oxidation and NO x reduction over a BaAl 2O 4 catalyst. By XRD analysis, the catalyst was shown to be of spinel structure. Temperature Programmed Oxidation (TPO) and Constant Temperature Oxidation (CTO) at 673 K show that the presence of O 2 decreases the ignition temperature of soot, and it enhances the conversion of NO x to N 2 and N 2O. The kinetic features of soot oxidation in the TPO test are similar to that in the TG–DTA analysis. Analysis by Diffuse Reflectance Fourier Infrared Transform Spectroscopy (DRIFTS) indicates that the nitrates formed from NO x adsorption and the C(O) intermediates from soot oxidation are the key precursors of the redox process between soot and NO x over surfaces of the BaAl 2O 4 catalyst. Moreover, DRIFTS tests suggest that nitrates act as the principal oxidants for C(O) oxidation, through which nitrates are reduced to N 2 and N 2O. The O 2 in the gas mixture presents a positive effect on the conversion of NO x to N 2 and N 2O by promoting the oxidation of nitrites into nitrates species.
Published Version
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