Improvements in NOx reduction by carbon using bimetallic catalysts

The catalysis of the C–NOx reaction has been studied to optimize the composition of the catalysts in order to decrease the carbon consumption by oxygen. Both the metal content and the composition of the catalysts have been investigated. The activity of bimetallic (KNi, NiCo and NiCu) catalysts for NOx reduction by carbon has been studied using both isothermal reactions at 300°C and temperature programmed reaction up to 500°C. It has been found that the experimental variables (i.e. amount of catalysts and nature of the bimetallic catalysts) determine the selectivity against carbon combustion by oxygen. Thus, it has been observed that the amount of catalyst greatly affects the C–O2 reaction but only lightly the C–NOx reaction and, consequently, modifies the selectivity of the catalyst for NOx reduction. Among the bimetallic catalysts tested, NiCu catalyst presents the best performance, at a temperature as low as 250°C, a high de-NOx activity and a high NOx selectivity due to a low carbon burn-off, with the additional advantage of the absence of N2O and CO in the reaction products. Thus, the results obtained in this study show, in comparison with our previous results, that better selectivities are achieved.