Modulating the Electronic Structures of Pt on Pt/TiO₂ Catalyst for Boosting Toluene Oxidation

Abstract

Surface hydroxyl groups commonly exist on the catalyst and present a significant role in the catalytic reaction. Considering the lack of systematical researches on the effect of the surface hydroxyl group on reactant molecule activation, the PtO x /TiO 2 and PtO x−y (OH) y /TiO 2 catalysts were constructed and studied for a comprehensive understanding of the roles of the surface hydroxyl group in the oxidation of volatiles organic compounds. The PtO x /TiO 2 formed by a simple treatment with nitric acid presented greatly enhanced activity for toluene oxidation in which the turnover frequency of toluene oxidation on PtOx/TiO 2 was around 14 times as high as that on PtO x−y (OH) y /TiO 2 . Experimental and theoretical results indicated that adsorption/activation of toluene and reactivity of oxygen atom on the catalyst determined the toluene oxidation on the catalyst. The removal of surface hydroxyl groups on PtO x promoted strong electronic coupling of the Pt 5d orbital in PtO x and C 2p orbital in toluene, facilitating the electron transfers from toluene to PtO x and subsequently the adsorption/activation of toluene. Additionally, the weak Pt−O bond promoted the activation of surface lattice oxygen, accelerating the deep oxidation of activated toluene. This study clarifies the inhibiting effect of surface hydroxyl groups on PtO x in toluene oxidation, providing a further understanding of hydrocarbon oxidation.

Catalytic Oxidation of Toluene over Pt/CeO2 Catalysts: A Double-Edged Sword Effect of Strong Metal–Support Interaction

“…In recent years, the catalytic materials of metal nanoparticles loaded on ceria surface have attracted wide attention, which show excellent performances for efficient oxidation of VOCs. − As a typical active support, the ceria support could take part in the reaction directly and accelerate oxygen circulation; moreover, a strong interaction between the noble metal and the ceria support might occur on the surface, bringing about charge transfer and atom migration. As a result, the electronic and structural properties of catalysts would be changed significantly, deeply influencing the catalytic activity, selectivity, and stability. − Lu et al found that tunable partial negative charges on Pt were achieved by suppressing roughening of the support surface, favoring O 2 spillover from TiO 2 to Pt . Zhang et al suggested that the Pt particle size would affect the chemical valence of Pt and adjust the strong metal–support interaction .…”