Ti/MCM-41 with highly active Si-O-Ti structures for efficient extraction and oxidative desulfurization of fuel oil

Oxidative desulfurization (ODS) is a promising technology for removing sulfur compounds from fuel oil under mild conditions. This study prepared Ti/MCM-41 catalyst using a simple adsorption-hydrolysis-argon calcination method and applied it to ODS. Carbon introduced by tetrabutyl titanate (TBOT) and generated by calcination in inert atmosphere restrains the growth of TiO 2 , thereby promoting the formation of a high-activity Si-O-Ti structure. By using the optimal Ti/MCM-41 catalyst, desulfurization rate of model oil (dibenzothiophene dissolved in decalin, 500 ppm of sulfur) as high as 99.8 % was achieved at 40 °C with methanol as extractant and H 2 O 2 as oxidant (O/S = 4). After six recycles, the S removal rate was still 97.9 %. Reaction conditions like reaction temperature and extractant were carefully analyzed to explore the active structure and reaction mechanism, deducing that Si-O-Ti species promote the reaction probably by forming highly active bis-hydroperoxo Ti species with five-membered ring structure. Moreover, the promotion of methanol effect was found and reasonably explained. This work provides important guidance to the design of new catalysts, selection of extractant and optimization of oxidant for more efficient phase-transfer extractive and catalytic oxidation desulfurization (ECODS) process.