An effective strategy for promoting toluene oxidation stability: Recrystallization Pt confinement and zeolite dealumination

The supported Pt-based catalysts exhibited excellent catalytic oxidation activity towards toluene, while the Pt metal was prone to aggregation at high temperatures, leading to catalyst sintering deactivation. A combination strategy was presented to enhance the reactivity and lifespan of catalysts for toluene catalytic oxidation in this work, which involved regulating the morphology and microstructure of Pt@D-Beta through a combination of recrystallization Pt confinement and zeolite dealumination to improve the stability and water resistance of the catalyst. The designed Pt@D-Beta catalyst with T 90 (temperatures for 90 conversion of toluene) at 158 °C was prepared by combining carrier dealumination and secondary crystallization method, which was 22 °C lower than that of traditional Pt/Beta. Importantly, the Pt@D-Beta catalyst exhibited excellent cycling performance and long-term stability, and great water resistance. After 5 cycle tests, the toluene conversion could also be maintained at ∼ 85 % for at least 50 h with slight activity loss. The results of SEM and XPS show that a combination of recrystallization Pt confinement and zeolite dealumination could improve the reduction performance of the catalyst, increase the dispersion of Pt on zeolite and oxygen mobility, and improve the catalytic performance of the catalyst for toluene. The toluene catalytic degradation on Pt@D-Beta was researched via in situ DRIFTs ( in situ diffuse reflectance infrared Fourier transform spectroscopy) combination with density functional theory (DFT) calculation, the hydroxyl groups on the catalyst can provide active oxygen for toluene catalytic oxidation, followed the Mars-van Krevelen (MvK) mechanism. This synthesis combination strategy is expected to provide an effective method for designing efficient zeolite limited noble metal catalysts for catalytic degradation of VOCs.