In situ FT-IR spectroscopic investigation of gold supported on tungstated zirconia as catalyst for CO-SCR of NO_x

摘要

The possibility for application of gold supported on tungstated zirconia as catalyst in the selective catalytic reduction of NO_xwith CO (CO-SCR) has been investigated by means of in situ FT-IR spectroscopy. Tungstated zirconia containing 18wt% of WO3 was prepared by co-precipitation. Gold was deposited on zirconia and tungstated zirconia by cationic adsorption using [Au(en)2]Cl3 as a precursor (en = ethylenediamine). The FT-IR spectra obtained during the interaction of CO with NO_x species adsorbed on the Au/ZrO2-WO_x and Au/ZrO2 samples revealed the formation of surface isocyanates attached to the gold particles. The generation of Au-NCO species occurred at low temperature (25-50 °C). The W-containing sample was characterized by higher activity in the ad-NO_x + CO reaction than the W-free one. It is shown that the nitrate species or adsorbed NO2 are essential for the generation of surface isocyanates and the oxidation of NO by oxygen is an important step. The obtained results suggest that Au catalysts supported on tungstated zirconia might be of interest for the selective reduction of NO_x with CO at low temperatures.