Enhanced oxidative desulfurization activity over NH2-MIL-125(HAc) through facet modulation by acetic acid and surface modification by amino group

Maximizing the exposure of active sites and improving the affinity between active sites and oxidants could help to realize exceptional catalytic oxidative performance for stubborn substrates, providing a promising desulfurization strategy for diesel fuels. In this work, Ti-based metal–organic frameworks (MOFs) MIL-125 with both higher exposure degree of {1 1 1} facets and amphiphilic surface modification were constructed through various rational design strategies based on facet effect and Janus-like effect. With the catalysis of MIL-125 after modulation by a monocarboxylic acid and modification by a functional group, dibenzothiophene (DBT), could be removed thoroughly (100 % sulfur removal) at 30 °C within 60 min, with only a 3:1 M ratio of H2O2 to DBT. Also, notable turnover frequency (TOF = 25.05 h−1) and satisfied recycling performance (at least 7 times) could be viewed. X-ray photoelectron spectroscopy (XPS) indicates higher Ti and O atomic concentrations (8.12 % and 30.35 %, respectively) on the surface of MIL-125 after modulation, attributed to the increased exposure of {1 1 1} facets. The amphiphilic nature of MIL-125 after modification is confirmed through contact angle (water contact angle = 26.6° and oil contact angle = 3.1°). Additionally, selective quenching experiments and electron spin-resonance spectroscopy analyses confirm that OH·, O2–·, and TiOO· all perform essential roles.