Gas-phase total oxidation of nitric oxide using hydrogen peroxide vapor over Pt/TiO2

Abstract

Pt/TiO2 catalysts with various Pt loadings (0.1–0.7 wt.%) were synthesized by a combined wet impregnation and H2-reduction method. The as-prepared catalysts were firstly reported being applied in thermal catalytic decomposition of hydrogen peroxide (H2O2) vapor for treating NOX. Physico-chemical properties of Pt/TiO2 catalysts were investigated by comprehensive techniques, including XRD, Raman, N2 adsorption–desorption, TEM, UV–vis DRS, XPS and PL spectroscopy. The activity tests showed that the incorporation of platinum into TiO2 led to a significant increase in the catalytic oxidation of NO compared with the unmodified TiO2. Toward NO oxidation from H2O2 vapor (molar ratio = 12/1), 0.3 wt.% Pt-TiO2 exhibited a remarkable activity in NOX removal (96.7%) and a high selectivity (89.2%) in their conversion to nitrate species under the optimal condition. XRD and TEM results show that ultrafine Pt particles were well dispersed on the surface of anatase-phase TiO2. XPS analysis indicated that Pt dopant existed as mainly metallic Pt(0) and a small portion of Pt2+ in as-prepared materials. The results of PL spectra demonstrated that the platinum nanoparticles on the TiO2 surface significantly accelerated electron transfer and served as active sites for the adsorption and activation of H2O2 molecules, to facilitate the generation of hydroxyl groups.