Lewis acidic controllable SiO2@TiO2 core-shell for enhanced catalytic oxidation of aromatic sulfides in diesel

Oxidative desulfurization is an important non‑hydrogen desulfurization technology, but traditional TiO 2 catalysts are subject to‌ the weak acidity and weak adsorption ability towards alkaline sulfide molecules, limited by the long reaction time for deep desulfurization. Herein, based on the principle of Lewis acid-base theory, this work reasonably designs the SiO 2 @TiO 2 core-shell catalyst, which combines excellent catalytic oxidative desulfurization activity and product separation performance. SiO 2 can regulate the acidity of TiO 2 and enhance the enrichment ability of substrate molecules, enhancing the charge transfer process and improving the catalytic performance of TiO 2 . Through systematic characterization, it is confirmed that the Lewis acidity of the core-shell structure originates from unsaturated Ti sites. And the thickness of the TiO 2 shell can be controlled to adjust the surface amounts of acid sites, strengthening the adsorption process of alkaline dibenzothiophenes. The mechanism research reveals the electron transfer between the SiO 2 core and the TiO 2 shell and the generated unsaturated Ti 3+ /Ti 4+ produce a synergistic effect. The generation rates of hydroxyl radicals(·OH) and alkoxy radicals (·OR) are accelerated while changing the Lewis acidity, efficiently adsorbing and oxidizing DBTs. The work expands the application of easy-separation mild Lewis acidic TiO 2 composite materials in the field of catalytic oxidation.