MIL-101 promotes the efficient aerobic oxidative desulfurization of dibenzothiophenes

Abstract

MIL-101 promotes the aerobic oxidation in n-dodecane of dibenzothiophene (DBT) and its methyl-substituted derivatives to their corresponding sulfone with complete selectivity, without observation of the sulfoxide. DBT sulfones can be completely separated from n-dodecane by water extraction. MIL-101(Cr) without the need of pre-activation was found more convenient than the also-active MIL-101(Fe) analog. The reaction exhibits an induction period due to the diffusion inside the pore system of the solvent or oxygen and it is not observed if the MIL-101 sample is first contacted with the solvent at the reaction temperature for sufficiently long times. MIL-101 is reusable for at least five times without any sign of deactivation according to the time-conversion plots. Evidence by electron paramagnetic resonance spectroscopy detecting the hydroperoxide radical adduct with a spin trapping agent and Raman spectroscopy detection of superoxide supports that the process is an autooxidation reaction initiated by MIL-101 following the expected radical chain mechanism inside the MIL-101 cages.

N‐Hydroxyphthalimide Anchored on Diamond Nanoparticles as a Selective Heterogeneous Metal‐free Oxidation Catalyst of Benzylic Hydrocarbons and Cyclic Alkenes by Molecular O2

“…Although the contribution of some leached NHPI from the solid to the solution cannot be ruled out, leached NHPI should promote oxidation in a very minor extent according to the previously commented experiment in where pure NHPI in a much higher amount than possibly leached out was used as catalyst, observing a slow progress of the oxidation reaction (Figure a). This radical chain mechanism was also supported by quenching experiment using p ‐benzoquinone as selective O 2 .− radical quencher (Supporting Information, Figure S9b) . When the reaction is started in the absence of p ‐benzoquinone and then, 20 mol % p ‐benzoquinone was added at 5 h reaction time, an almost complete quenching of the reaction was observed, supporting the intermediacy of superoxide radical ions as a radical intermediate.…”

Enhancement of Oxidative Desulfurization Performance over UiO‐66(Zr) by Titanium Ion Exchange

“…Garcia et al. investigated the aerobic ODS of DBT by using MIL‐101(Cr) as a catalyst . More recently, Balula et al.…”

Oxidation of refractory sulfur compounds with molecular oxygen over a Ce–Mo–O catalyst

“…To address this issue, selective quenching experiments were conducted with BQ or DMSO as O 2•− or HO • quenchers,38 …”