Facile Synthesis of a Nanocrystalline Metal–Organic Framework Impregnated with a Phosphovanadomolybdate and Its Remarkable Catalytic Performance in Ultradeep Oxidative Desulfurization

Abstract

Reducing the level of sulfur content in fuel oils has long been desired for environmental reasons. Polyoxometalates (POMs) can act as catalysts to remove sulfur‐containing heterocyclic compounds by the process of oxidative desulfurization under mild conditions. However, one key obstacle to the development of POM‐based catalysts is the poor solubility of POMs in the overall nonpolar environment. We report a novel strategy for the introduction of catalytically active POMs into nonpolar reaction systems by encapsulating the inorganic catalyst within the pores of a metal–organic framework structure in which the organic ligands act as hydrophobic groups. The nanocrystalline catalysts, obtained rapidly and conveniently by both solution and mechanochemical synthesis, showed remarkable activities in catalytic oxidative desulfurization reactions in both a model diesel environment and in real diesel wherein dibenzothiophene was converted rapidly and quantitatively into dibenzothiophene sulfone.

Porous Molybdenum‐Based Hybrid Catalysts for Highly Efficient Hydrogen Evolution

“…Moreover,r emoving Cu from the composite structure can further permit HER performance gains (Figure S13). Compared with the physical mixture of commercial MoO 2 and acetylene black (MoO 2 -AB), the MoO 2 @PC catalyst shows ad ramatically enhanced HER performance possibly because of the use of POMOFs as precursors,which can form porous carbon with large areas and hierarchical pores.I na ddition, al ittle amount of Pd oped in MoO 2 @PC also provides ap ositive contribution to the measured remarkable HER activity.T ov erify this,w es ynthesized MoO 2 @SiC by using the same POMOFs structure (NENU-4) [16] except that H 3 SiMo 12 O 40 was used to replace H 3 PMo 12 O 40 .I tc learly shows that MoO 2 @PC has am ore positive onset potential value and h 10 than those of MoO 2 @SiC,p roving the important role of phosphorus doping for the HER (Figure 2a) (Table S3). TheH ER kinetics of the above-mentioned catalysts was further evaluated by corresponding Tafel plots (log j~h).…”

“…[16] Third, the agglomeration of MoO 2 can be avoided by confining the carbon skeleton, and MoO 2 @PC hybrids are loaded onto RGO uniformly because of the distinct structure of the POMOFs/GO composite.Phosphorus (0.37 at. %) is doped with MoO 2 @PC-RGO through P À Oand P À Cbonds,which are not negligible and increase the catalytic activity.O verall, the MoO 2 @PC-RGO nanocomposite displays an excellent HER activity in acidic media, with the onset potential close to 0mV( vs.t he reversible hydrogen electrode,RHE), approaching that of commercial 20 %Pt/C.…”

Desulfurization of model diesel by extraction/oxidation using a zinc-substituted polyoxometalate as catalyst under homogeneous and heterogeneous (MIL-101(Cr) encapsulated) conditions

“…The stability of POMs combined with their structural flexibility to incorporate various elements in their framework make them attractive catalysts. To date, POMs have proved to be among the best catalysts for ODS processes [6][7][8][20][21][22][23][24][25][31][32][33][34][35]. One of the main characteristics that limits the use of POMs as catalysts is their generally good solubility, which complicates their recovery and reuse.…”

“…One of the main characteristics that limits the use of POMs as catalysts is their generally good solubility, which complicates their recovery and reuse. In recent years many strategies have been developed to immobilize homogenous POMs in various supports to form new catalytically active and easily recoverable materials [7,[20][21][22][23][29][30][31][32][33][36][37][38][39][40][41]. There are different kinds of materials that can be used as solid supports: mesoporous silica, TiO 2 and Al 2 O 3 nanocomposites and microporous materials such as zeolites and metal-organic frameworks (MOFs).…”

In situ synthesis of a novel dioxidovanadium-based nickel complex as catalyst for deep oxidative desulfurization with molecular oxygen

“…Yet, only a few examples were reported on the oxidation of those refractory sulfur-containing compounds with molecular oxygen [10]. Recently, the vanadiumcontaining polyoxometalates (POMs) have been used as amphiphilic [11] and POMs@MOFs crystalline catalysts [12] for the oxidation of sulfur-containing compounds with molecular oxygen and they can be oxidized to corresponding sulfoxides and sulfones, which can be readily removed by solvent extraction. However, the cumbersome preparation, the inherently metastable character or the use of large amount of isobutyl aldehydes limited their potential application.…”