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Highly active Keggin-type silicotungstic acid (SiW12) with oxygen vacancy (Ov) defects was encapsulated into the magnetic floral N-doped carbon microspheres (γ-Fe2O3@NC-300) through the facile one-step air pyrolysis of the precursor comprising core–shell Fe3O4@polydopamine (Fe3O4@PDA) and SiW12 to prepare γ-Fe2O3@NC@SiW12-300. The fabricated catalysts were systematically characterized and subsequently employed for the oxidation desulfurization (ODS) of the model fuel. The magnetic floral γ-Fe2O3@NC@SiW12-300 catalyst exhibited nearly perfect catalytic activity, which under mild conditions could remove 100% amount of 4000 ppm DBT in model fuel within 20 min (0.03 g catalysts and n(H2O2)/n(S) of 2). The catalyst activity is mainly attributed to the high activity SiW12 with the Ov defect and its outstanding dispersibility in γ-Fe2O3@NC, along with the high number of exposed active sites. A selected catalyst, γ-Fe2O3@NC@SiW12-300, showed a noticeable turnover frequency (TOF) (110.07 h−1) and lower activation energy (38.79 kJ mol−1) in oxidative desulfurization (ODS) with good recyclability. HO˙ radical was found to be the active species involved in ODS as confirmed by the EPR and scavenger experiments. Additionally, the fabricated catalyst can be conveniently separated and recycled within an externally applied magnetic field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mo 2 C nanoparticles was well-dispersed on N-doped graphene via in-situ carbonization of the PMo 12 -PEI/GO precursor. • Mo 2 C@NC/NrGO presented the maximum kinetic constant of 0.35 min−1 for ODS of liquid fuel with 4000 ppm of the initial S content. • The radical scavenging experiments revealed a ODS mechanism of HO• radicals. A new composite Mo 2 C@NC/NrGO, with very small and well-distributed molybdenum carbide (Mo 2 C) nanoparticles on N-doped graphene, was prepared via carbonization of the tricomponent composite PMo 12 -PEI/GO comprising phosphomolybdic acid (H 3 PMo 12 O 40 ·xH 2 O), polyethyleneimine (PEI), and graphene oxide (GO). The as-prepared Mo 2 C@NC/NrGO exhibited outstanding oxidative desulfurization (ODS) performance and achieved the ultra-deep desulfurization of liquid fuel under mild conditions, which was attributed to the synergistic effect of extraction and catalytic oxidation. In particular, catalytic oxidation played a dominant role, which originated from the excellent characteristics of Mo 2 C@NC/NrGO, such as the small size and even distribution of Mo 2 C on graphene, as well as the improved activation of oxidant by the electronic transfer of N-doped graphene to Mo 2 C. For oxidative desulfurization (ODS) of 4000 ppm of DBT, Mo 2 C@NC/NrGO showed the high kinetic constant (＞0.35 min−1), which can make 4000 ppm of DBT removed completely within 10 min. A HO• radical mechanism for oxidative desulfurization (ODS) of fuel oils was revealed on the basis of radical experiments and electron paramagnetic resonance (EPR). Moreover, the prepared catalyst presented a good recyclability for six runs with no significant loss of activities. Overall, Mo 2 C@NC/NrGO could be suggested as a prospective catalyst for ODS. [ABSTRACT FROM AUTHOR]

A ternary nanocomposite comprising phosphotungstic acid (PW 12), polyethyleneimine (PEI), and graphene oxide (GO), i.e., PW 12 -PEI/GO, was developed as a precursor to obtain the W 2 C/N-rGO catalyst upon in-situ carbonization. W 2 C/N-rGO was applied in the deep oxidative desulfurization (ODS) of liquid fuel, and exhibited extraordinary performance due to the ultrafine W 2 C nanoparticles (～3–5 nm) evenly dispersed on N-rGO and the electron-donating effect of N-rGO on W 2 C. 4000 ppm of DBT in model oil could be completely removed within only 10 min with a remarkably high turnover frequency (168 h−1) and the lower activation energy (30.9 kJ·mol−1). Radical experiments and density functional theory calculations indicate that the ODS reaction proceeds mainly via a HO• radical mechanism. Moreover, W 2 C/N-rGO could be recycled for 6 successive cycles with no obvious loss of performance. [Display omitted] • Ultrafine W 2 C nanoparticles was well-dispersed on N-doped graphene upon in-situ carbonization of the PW 12 -PEI/GO precursor. • W 2 C/N-rGO showed ultrafast ODS performance for fuel oil with the initial S content of 500‐6000 ppm. • DFT calculation and the radical scavenging experiments revealed a ODS mechanism of HO• radicals. • Ultrafine W 2 C nanoparticles and the electron-donating effect of N-rGO on W 2 C significantly improved ODS performances. [ABSTRACT FROM AUTHOR]

[Display omitted] • W 2 C@C was prepared via annealing ZnQPc/PW 12 composites at 800 °C. • Zn could promote the formation of the pure-phase W 2 C during annealing process. • W 2 C@C was firstly used as an ODS catalyst and showed remarkable performance. • DFT calculation revealed the non-radical oxidation mechanism of thiophenics over W 2 C. Herein, the tungsten carbide (W 2 C) coated with the ultrathin carbon layer (W 2 C@C) was firstly exploited as an efficient and stable oxidative desulfurization (ODS) catalyst, which was prepared via annealing metallophthalocyanine/phosphotungstic acid composites at 800 °C under N 2 atmosphere. The Zn element in precursor markedly promoted the formation of the pure-phase W 2 C during annealing process. W 2 C@C showed a remarkable ODS performance with H 2 O 2 as oxidant under mild conditions. Dibenzothiophene (DBT) was100% removed by W 2 C@C within 40 min at 50 °C. The density functional theory (DFT) calculations combined with the radical scavenging experiments suggest that the ODS over W 2 C@C follows a non-radical mechanism that involves the facile formation of surface active oxygen species. Moreover, the W 2 C@C catalyst could be easily regenerated by solvent washing and recycled with no obvious loss of performance. Therefore, W 2 C could be firstly suggested as a promising catalyst for the ODS of liquid fuels. [ABSTRACT FROM AUTHOR]

Poly (glycidyl methacrylate) (PGMA) was grafted onto the SiO 2 surface to prepare the hairy particles PGMA/SiO 2 using the "grafting from" method, and then vacant Wells-Dawson-type polyoxometalates (POMs) was covalently bonded to PGMA/SiO 2 using the silane coupling agent to prepare heterogeneous catalyst POM-PGMA/SiO 2. It is highly efficient and selective for tetrahydrothiophene (THT) oxidation. The oxidation process of THT catalyzed by POM-PGMA/SiO 2 using H 2 O 2 presented some special characters. POM-PGMA/SiO 2 showed a certain microenvironment effect of the carrier, and effectively promoted the THT oxidation. There are optimal values for both the amount of POM-PGMA/SiO 2 and the bonding amount of POM for THT oxidation, and the excessive catalyst and too high density of catalytic active sites can both decrease the catalytic activity. Alkalinity is not conducive to oxidation of THT with H 2 O 2. More attractively, POM-PGMA/SiO 2 could be well reused several times, stemming from the strong covalent bonding between the POM clusters and the polymers on SiO 2 surface. Image 1 • Hairy particles covalently supported catalysts (POM-PGMA/SiO 2) are designed and prepared. • The catalytic oxidation of THT by P 2 W 17 -PGMA/SiO 2 presented some special characters. • P 2 W 17 -PGMA/SiO 2 showed a certain microenvironment effect for the oxidation of THT. • The desulfurization rate of THT reached 100% at room temperature for a short time (60 min). • P 2 W 17 -PGMA/SiO 2 could be recycled several times with little loss of detectable catalytic activity. [ABSTRACT FROM AUTHOR]