Enhanced Catalytic Activity of Pd Supported on TiO2 Nanowire for the H2-SCR of NO x in the Presence of Oxygen

Catalytic removal of NO x byenvironmentally benign H-2 will contribute to the sustainabledevelopment of the world. A Pd supported on a TiO2 nanowire (Pd/TiO2-NWs) catalyst was fabricated, and the catalytic performanceforthe selective catalytic reduction of NO x by H-2 (H-2-SCR) was investigated. It was foundthat the Pd/TiO2-NW catalyst exhibited higher H-2-SCR activity and wider activity temperature window than Pd supportedon the TiO2 nanoparticle (Pd/TiO2-P) catalyst.Based on a series of characterizations, Pd/TiO2-NWs witha nanowire structure possessed a large surface area, high Pd dispersion,high content of metallic Pd, and more surface adsorbed oxygen, allof which would contribute to the adsorption and activation of NO x and the spillover of hydrogen. Whereas forthe Pd/TiO2-P catalyst, the favorable active Pd-0 site is absent. In situ DRIFTS showed that more active intermediates(NO2, monodentate nitrate, and NH3 species)were formed over Pd/TiO2-NWs than the Pd/TiO2-P catalyst. All of these contributed to the enhanced H-2-SCR activity of the Pd/TiO2-NW catalyst.

Automated summary

The Pd/TiO2 nanowire catalyst exhibited higher H-2-SCR activity and wider activity temperature range compared to the Pd/TiO2 nanoparticle catalyst. This is attributed to the larger surface area, higher Pd dispersion, higher metallic Pd content, and increased surface adsorbed oxygen of the nanowire structure, which enhance the adsorption and activation of NO x and the spillover of hydrogen.