Construction of a polyoxometalate-based composite catalyst for efficient extractive and oxidative desulfurization of fuel

Abstract

A novel polyoxometalate-based composite SiO 2 @VTES@IL-PW 11 was constructed via stepwise functionalization of mesoporous SiO 2 with vinyltriethoxysilane (VTES) and lacunary Keggin-type phosphotungstate (PW 11 ). This design features a synergistic integration of three functional components: the mesoporous SiO 2 support serves as a high-surface-area platform, the VTES linker introduces hydrophobic surface properties that facilitate substrate enrichment, and the imidazolium-based ionic liquid stabilizes the lacunary PW 11 species while creating a favorable microenvironment for oxidation reactions. The successful immobilization of PW 11 onto the support was confirmed by FT-IR, N 2 adsorption-desorption, TGA, XPS, TEM, and EDS. Catalytic tests demonstrated that the SiO 2 @VTES@IL-PW 11 exhibits excellent desulfurization activity, achieving 99.49% DBT removal under the optimized reaction conditions. The oxidation of DBT followed pseudo-first-order kinetics with an apparent activation energy of 14.26 kJ·mol -1 . The catalyst also showed good activity toward various sulfur compounds, with removal efficiencies following the order DBT > 4-MDBT > 4,6-DMDBT > BT. Notably, the catalyst maintained a DBT removal efficiency of over 94% after ten consecutive cycles, demonstrating exceptional structural stability and reusability. This work provides a promising strategy for the design of efficient and stable polyoxometalate-based catalysts for fuel desulfurization.