A simple controlled assembly strategy for multi-coordinated Ti derived in non-calcinated amorphous Ti-Si mixed gel: strengthened deep catalytic oxidative desulfurization

This work addresses the atomic radius mismatch between Ti and Si and their limited substitution frequency by developing a sol–gel strategy to optimize active Ti site formation. A dual regulation approach, involving water and organic acids, controlled the hydrolysis rate and implemented a two-step process, forming Si-OH and Ti-OH bridging units. This enabled precise control over elemental assembly within the sol–gel system. Stabilization of the TiO x -SiO 2 mixed phase facilitated the formation of a highly active, amorphous TS aerogel catalyst, enriched with penta- and hexa -coordinated Ti. By optimizing preparation parameters, an efficient TS (1:4) aerogel catalyst was developed, achieving complete oxidative desulfurization (ODS) of 500 ppm DBT at 333 K in 10 min, with a maximum reaction rate constant (Kobs) of 0.447 min −1 and activation energy of 50.05 kJ/mol. The catalyst maintained ∼90 % desulfurization efficiency over six consecutive cycles using model oil containing sulfur compounds (BT, DBT, 4,6-DMDBT). Insights into peroxide transfer and catalyst degradation were obtained through multi-factor activity tests, active site evolution analysis, and DFT calculations. These findings improve Ti site optimization and provide a basis for refining sol–gel strategies to increase active Ti content.