Immobilization of LaW₁₀ onto Ionic‐Liquid‐Modified Mesoporous Silica: Deep Desulfurization with Zero‐Order Reaction Kinetics

Abstract

The polyoxometalate (POM) cluster Na7H2LaW10O36⋅32 H2O (denoted LaW10) is immobilized onto dihydroimidazolium‐based ionic‐liquid (IL)‐modified mesoporous silica, resulting in the formation of a new catalyst: LaW10/IL‐SiO2. Compared with other reported extractive catalytic oxidative desulfurization (ECODS) systems, LaW10/IL‐SiO2 has the following advantages: 1) the heterogeneous catalyst LaW10/IL‐SiO2 achieves deep desulfurization of dibenzothiophene (DBT), benzothiophene (BT), and 4,6‐dimethyldibenzothiophene (4,6‐DMDBT) in 25, 30, and 25 min, respectively, under mild conditions; 2) deep desulfurization of DBT follows zero‐order reaction kinetics; 3) there is no need to add ionic liquid each time the catalyst is reused; 4) the catalyst can be separated easily by filtration and reused at least ten times without a decrease in catalytic efficiency. As such, LaW10/IL‐SiO2 shows great potential for practical applications.

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

“…Therefore, BMIPF 6 was elected as the preferred extraction solvent. The efficiency of ILs as extraction solvents has already been reported in the literature for desulfurization systems [6,17,[59][60][61], and particularly the efficiency of BMIPF 6 in ODS systems has been recognized [7,8,62,63]. A possible reason for the superior catalytic oxidation in the presence of this IL compared with MeCN may be the immiscibility of the IL with the aqueous oxidant.…”

“…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).…”

“…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 most promising methods is oxidative desulfurization (ODS) [4,5]. In this process, the refractory sulfur compounds are oxidized to sulfoxides and sulfones with subsequent removal of these products by extraction or adsorption [5][6][7][8][9][10][11][12]. Ionic liquids (ILs) have proved to be successful as sustainable extraction solvents for the removal of oxidized sulfur compounds from fuels and model fuel oils, replacing volatile and flammable organic solvents [6,8,9,[13][14][15][16][17][18].…”

A multicomponent assembly approach for the design of deep desulfurization heterogeneous catalysts

“…To improve the phase transfer ability for a heterogeneous catalyst, ionic liquids are frequently used to provide the suitable environment to enhance phase transfer as well as the spatial proximity between substrates and the catalytic active component; 19,20 2) the supports should not only exhibit strong interactions with the active components, but also provide the necessary structural integrity which will prevent the leaching of the active components; 21,22 3) most importantly, the catalysts should retain their reactivity and structural stability during recycling process. 23,24 Herein, we report the design and preparation of an heterogeneous catalyst, Mg3Al-IL-EuW10, which was prepared by intercalating Na9(EuW10O36)·32H2O (Na-EuW10) clusters into the ionic liquids (ILs) modified layered double hydroxides (LDHs). The extractive and oxidative desulfurization experiments indicate that almost 100 % sulfur removal of DBT, 4,6-DMDBT and BT can be achieved using Mg3Al-IL-EuW10 as catalyst and H2O2 as oxidant at 70 o C in 25, 30 and 40 min, respectively.…”