An organic–inorganic hybrid compound constructed by polytungsto-vanadosilicate and hexadecyltrimethyl ammonium as an efficient catalyst for demercaptanization of crude oil

High Oxidation Desulfurization of Fuels Catalyzed by Vanadium-Substituted Phosphomolybdate@Polyaniline@Chitosan as an Inorganic-Organic Hybrid Nanocatalyst

From the environmental protection and human health perspectives, the design and synthesis of efficient and reusable oxidative desulfurization nanocatalysts has always been sought after by scientists and industries. In this regard, a new heterogeneous nanocatalyst (V-SPM@PANI@CH) was synthesized by immobilizing Keggin-type vanadium-substituted phosphomolybdate ([PVMo₁₁O₃₉]^4-) (named V-SPM) clusters on the surface of polyaniline (PANI) and chitosan (CH) polymers. The features of the assembled nanocatalyst were detected by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques in detail. The XRD studies indicated that the average crystallite size of V-SPM@PANI@CH was estimated to be about 36 nm. The catalytic performance of V-SPM@PANI@CH was investigated in the extractive and catalytic oxidation desulfurization (ECOD) procedure of real and thiophenic model gasoline by H₂O₂/AcOH (volume proportion of 2:1) as an oxidizing system. The optimal desulfurization conditions for ECOD reactions were as follows: 50 mL of model/real gasoline, 0.1 g of V-SPM@PANI@CH, reaction time of 60 min, and reaction temperature of 35 °C. Under the experimental conditions outlined above and the designed ECOD system, the content of sulfur in real gasoline could decline from 0.4985 to 0.0193 wt %, which corresponds to an efficiency of 96%. Moreover, the removal percentage of aromatic hydrocarbons, including thiophene (Th), benzothiophene (BT), and di-benzothiophene (DBT) as model fuels decreases in the order of DBT ≥ BT > Th under identical operating conditions. High catalytic activity was maintained with only a slight loss during five cycles. This work offers the ECOD system (V-SPM@PANI@CH/AcOH/H₂O₂) for the desulfurization of liquid fuels, which had a great repercussion on the ECOD efficiency.

Synthesis of modified amphiphilic quaternary ammonium silicotungstate and its application in heterogeneous catalytic oxidative desulfurization

Mechanism of amphiphilic quaternary ammonium silicotungstate for oxidative desulfurization.

Catalytic oxidative desulphurization of gasoline using amphiphilic polyoxometalate@polymer nanocomposite as an efficient, reusable, and green organic-inorganic hybrid catalyst

To preparation of ultra-clean gasoline fuel, a new amphiphilic nanocomposite (TBA-SiWMn@PVA) has been successfully synthesized by supporting sandwich-type silicotungstate polyoxometalate ((n-C₄H₉)₄N)₇H₅Si₂W₁₈Mn₄O₆₈ (TBA-SiWMn) on polyvinylalcohol (PVA) as an efficient catalyst for catalytic oxidative desulphurization (CODS) of gasoline. The synthesized materials were characterized by means of elemental analysis, ¹¹³Mn NMR, ²⁹Si NMR, XRD, SEM, FT-IR and UV-vis techniques. The catalytic activity of TBA-SiWMn@PVA nanocomposite was tested on real gasoline in the presence of CH₃COOH/H₂O₂ as an oxidant and the results were compared with model sulphur compounds at the same conditions. The TBA-SiWMn@PVA nanocomposite was shown excellent catalytic performance and recoverability for ODS of gasoline with high yield. The effects of the reaction time, reaction temperature, dosage and nature of catalyst were investigated. The reaction mechanism and the kinetic parameters of sulphur compounds oxidation were also discussed. The probable mechanism was proposed via the electrophilic mechanism through the formation of a peroxometalate intermediate complex with phase transfer properties. Results were indicated that the kinetics of sulphur oxidation fitted the pseudo-first-order kinetic model. After 5 oxidation runs, the heterogeneous nanocatalyst was separated and recovered easily.

An organic–inorganic hybrid based on an Anderson-type polyoxometalate immobilized on PVA as a reusable and efficient nanocatalyst for oxidative desulphurization of gasoline

An organic–inorganic hybrid based on Anderson-type polyoxometalate was synthesized and immobilized on PVA via sol–gel method and characterized by FT-IR, XRD, SEM and UV-vis spectroscopy. Its catalytic activity was tested on ODS of gasoline.