NO selective reduction by hydrogen over bimetallic Pd-Ir/TiO2 catalyst

TiO2 supported monometallic and bimetallic catalysts were prepared and employed in the selective catalytic reduction of nitrogen oxides by hydrogen (H-2-SCR). Bimetallic Pd-Ir/TiO2 exhibited high activity in H-2-SCR reaction and NOx conversion of >80%, with N-2 selectivity >80%, could be obtained in the temperature range of 413-473K. The existence states of supported metals before and after H-2-SCR were investigated by X-ray photoelectron spectroscopy, and the surface species formed during H-2-SCR reaction were monitored by in situ FTIR spectroscopy. Based on the catalytic and characterization results, the synergistic effects between Pd and Ir were discussed and the H-2-SCR reaction pathways over Pd-Ir/TiO2 were proposed. (C) 2012 Elsevier B.V. All rights reserved.