Unraveling the Promotional Effect of Co on the Pd/TiO<sub>2</sub> Catalyst for H<sub>2</sub>-SCR of NO<i><sub>x</sub></i> in the Presence of Oxygen
Yiyang Zhang, Shiyu Xu, Junhua Li, Erlei He, Zhiming Liu
Abstract
The effect of the introduction of Co to the Pd/TiO 2 catalyst for selective catalytic reduction of NO x by H 2 (H 2 -SCR) in the presence of oxygen has been systematically investigated in the present study. The additive Co can not only obviously improve NO x conversion but also enhance N 2 selectivity. The added Co induced the formation of Pd 0 over the bimetallic PdCo/TiO 2 catalyst, which is greatly conducive to the H 2 -SCR reaction. The spillover of H 2 was promoted due to the introduction of Co over PdCo/TiO 2 . In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed that the addition of Co not only contributed to the adsorption and activation of NO x but also led to the generation of NH 3 species adsorbed on Lewis acid sites, making the reduction of NO x by the H 2 -SCR combined with NH 3 -SCR routes. All of these are responsible for the enhanced catalytic performance of the bimetallic PdCo/TiO 2 catalyst. The investigation would provide guidelines for the rational design of a highly active H 2 -SCR catalyst for the removal of NO x .