An investigation on the mechanism of NO decomposition over Rh/SiO2 catalysts in presence of pulse injected H2

Rh/SiO2 catalysts were prepared by sol-gel, micro-emulsion and grafting methods. They were characterized by BET, EDXRF and TEM. Their catalytic activity was studied for NO decomposition under steady state transient conditions with pulse injected H2. The reactions were carried out in the temperature range of 100-400 °C. NO, N2O, NO2, O2, H2, NH3, N2 and H2O were monitored and analyzed by mass spectroscopy. Rh/SiO2 catalysts were highly active and selective for NO reduction to N2. H2 pulse experiments revealed that pulse injected H2 removed the adsorbed atomic oxygen and nitrogen species from the catalyst surface to form water and NH3, respectively. Based on the pulse experiments, the mechanism for the formation of N2, H2O, NH3 and N2O has been proposed.