Pt/SBA-15 as a Highly Efficient Catalyst for Catalytic Toluene Oxidation

Abstract

The catalytic oxidation of toluene has been investigated using a series of Pt/SBA-15 and Pt/SiO2 catalysts, and the Pt/SBA-15 catalyst exhibits significantly higher catalytic activity for the oxidation of toluene than the Pt/SiO2 catalysts. The SBA-15-supported Pt nanoparticles possess the ability to strongly dissociate toluene to benzene, hydrocarbon fragments (CHx), and H2 at low temperatures, but the Pt/SiO2 catalysts are nonreactive toward the decomposition of toluene. The products resulting from the dissociation of toluene were easily oxidized by oxygen, thereby positively affecting the conversion rate of toluene oxidation on Pt/SBA-15. Temperature-programmed desorption measurements clearly indicate that the dissociation reaction mainly consists of breakage of the C–C bonds between the phenyl and methyl groups. Combined density functional theory (DFT) calculations and DRIFT spectroscopy are carried out to investigate the stretching frequency of CO adsorbed on the defect sites of various Pt clusters, suggesting that the subnanosized Pt particles (icosahedron cluster) and/or Pt single atom may be formed in the structure of SBA-15. Pt sites associated with low coordination and subnanoscale Pt particles and/or single Pt atoms in the SBA-15 support can facilitate toluene adsorption and induce strong dissociation.