Kinetic evaluation of direct NO decomposition and NO-CO reaction over dendrimer-derived bimetallic Ir-Au/Al2O3 catalysts

The effects of Au on the catalytic performance of Ir metal towards NO reduction by CO and direct NO decomposition have been investigated over dendrimer-derived Ir-Au bimetallic catalyst. Results were also compared to a catalyst prepared by conventional incipient wetness impregnation of metal salts. Characterization of Ir-Au bimetallic samples using scanning transmission electron microscopy, H-2 chemisorption and temperature programmed desorption of NO reveals that highly dispersed Ir-Au particles can be obtained by dendrimer templating method. In-situ transmission Fourier transform infrared spectroscopy following adsorption of probe molecules (i.e., CO and NO) on the dendrimer-derived Er-Au bimetallic sample indicated the presence of electron transfer from Ir to Au sites. In contrast, a geometric effect of Au on Ir was observed over the conventional-derived sample, consistent with X-ray photoelectron spectroscopy measurements. These properties influence the catalytic performance, with higher selectivity towards N2O and a better intrinsic catalytic turnover frequency for reduction of NO by CO and NO decomposition observed for the dendrimer-derived sample. Overall, the results suggest that both NO-CO and NO decomposition reaction are structure-sensitive reactions. (c) 2014 Elsevier B.V. All rights reserved.