In situ FT-IR spectroscopic investigation of gold supported on tungstated zirconia as catalyst for CO-SCR of NO x

The possibility for application of gold supported on tungstated zirconia as catalyst in the selective catalytic reduction of NO x with CO (CO-SCR) has been investigated by means of in situ FT-IR spectroscopy. Tungstated zirconia containing 18 wt% of WO 3 was prepared by co-precipitation. Gold was deposited on zirconia and tungstated zirconia by cationic adsorption using [Au(en) 2]Cl 3 as a precursor (en = ethylenediamine). The FT-IR spectra obtained during the interaction of CO with NO x species adsorbed on the Au/ZrO 2-WO x and Au/ZrO 2 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 NO 2 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. © 2012 Elsevier B.V