Oxidation and decomposition of NH₃ over combustion synthesized Al₂O₃ and CeO₂ supported Pt, Pd and Ag catalysts

Abstract

The catalytic oxidation and decomposition of NH₃ have been carried out over combustion synthesized Al₂O₃ and CeO₂supported Pt, Pd and Ag catalysts using temperature programmed reaction (TPR) technique in a packed bed tubular reactor. Metals are ionically dispersed over CeO₂ and fine metal particles are found on Al₂O₃. NH₃ oxidation occurs over 1% Pt/ Al₂O₃, 1% Pd/ Al₂O₃ and 1% Ag/Al₂O₃ at 175, 270 and 350 °C respectively producing N₂, NO, N₂O<i> </i>and H₂O, whereas 1% Pt/ CeO₂, 1% Pd/ CeO₂ and 1% Ag/ CeO₂ give N₂ along with NO, N₂O and H₂O at 200, 225 and 250 °C respectively. N₂

predominates over other nitrogen-containing products during the reaction on all catalysts. At less O₂ concentration, N₂ and H₂O are the only products obtained during NH₃ oxidation. NH₃ decomposition over all the catalysts occurs above 450 °C.