Enhanced Catalytic Activity of Pd Supported on TiO<sub>2</sub> Nanowire for the H<sub>2</sub>-SCR of NO<sub><i>x</i></sub> in the Presence of Oxygen
Shiyu Xu, Yiyang Zhang, Christopher Hardacre, Zhiming Liu
Abstract
A Pd supported on a TiO 2 nanowire (Pd/TiO 2 -NWs) catalyst was fabricated, and the catalytic performance for the selective catalytic reduction of NO x by H 2 (H 2 -SCR) was investigated. It was found that the Pd/TiO 2 -NW catalyst exhibited higher H 2 -SCR activity and wider activity temperature window than Pd supported on the TiO 2 nanoparticle (Pd/TiO 2 -P) catalyst. Based on a series of characterizations, Pd/TiO 2 -NWs with a nanowire structure possessed a large surface area, high Pd dispersion, high content of metallic Pd, and more surface adsorbed oxygen, all of which would contribute to the adsorption and activation of NO x and the spillover of hydrogen. Whereas for the Pd/TiO 2 -P catalyst, the favorable active Pd 0 site is absent. In situ DRIFTS showed that more active intermediates (NO 2, monodentate nitrate, and NH 3 species) were formed over Pd/TiO 2 -NWs than the Pd/TiO 2 -P catalyst. All of these contributed to the enhanced H 2 -SCR activity of the Pd/TiO 2 -NW catalyst.