Unexpected larger Pt nanoparticles induced by N,N-dimethylformamide on SBA-15 for enhanced low-temperature catalytic oxidation of toluene

Low-temperature catalytic oxidation is a prevalent technology for toluene removal due to its reduced energy demand. In this study, N,N-dimethylformamide (DMF) was used to control the particle size of active metals. The activity tests revealed that Pt nanoparticles with a particle size of 5–15 nm exhibited higher activity for toluene oxidation and maintained good hydrothermal stability on the SBA-15 support. The results suggest that despite the increase of Pt particle size by using DMF, the proportion of Pt⁰ and the oxygen activation ability were both increased. The reaction pathway of the toluene oxidation over Pt/SBA-15 was examined in depth by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) and cluster analysis, revealing that the benzyl alcohol, benzaldehyde, and benzoic acid species were primary intermediate products. The benzaldehyde on the larger Pt nanoparticles is conducive to decomposing and generating CO₂ for complete mineralization, promoting the activity of toluene oxidation. This work highlights the significance of DMF-induced size effects in the development of low-temperature oxidation catalysts and understanding of reaction mechanism, guiding the design of new efficient toluene oxidation catalysts.