Reduction mechanism of selective NO reduction on Pd-NiO/(Y0.99Ba0.01)2O3 catalyst

Abstract

Y(Ba)2O3 catalyst loaded with 1wt% Pd and 3.2wt% NiO, Pd-NiO/(Y0.99Ba0.01)2O3, was found to be highly active to the selective reduction of NO with C3H6. The adsorption of NO on both (Y0.99Ba0.01)2O3 and Pd-NiO loaded one was studied using temperature-programmed desorption, pulsed reaction analysis and in-situ Fourier transform infrared (FTIR) spectroscopy. It was determined that NO is readily adsorbed on (Y0.99Ba0.01)2O3, primarily via the formation of nitrite and nitrate species. The addition of Pd-NiO assists in activating NO decomposition at lower temperatures as well as increasing the extent of NO adsorption. The reaction of NO with C3H6 and O2 on the Pd-NiO/(Y0.99Ba0.01)2O3 was also studied using pulsed reaction analysis and in-situ FTIR under NO selective reduction condition. The results demonstrated that the mechanism involves the reaction of −C2Hx or −CH3 adsorption species generated via the disproportionation of C3H6 with nitrate species to form CNO or C2HxNOy (x, y=2,3) intermediates. These intermediates readily react with NO and O2 to form the products CO2, N2 and H2O.