Synthesis of a nanocomposite based on chitosan and modified heteropolyanion as a nanocatalyst for oxidative desulfurization of real and thiophenic model fuels

Abstract

An efficient catalytic oxidative desulfurization (CODS) strategy has been developed using an organic-inorganic hybrid phase-transfer type nanocatalyst (IMID-KTHPA@CTS). A new organic-inorganic hybrid phase transfer nanocatalyst based on chitosan polymer (CTS) and Keggin-type heteropolyanion (KTHPA) was prepared by modification of heteropolyacid (H₃PW₁₂O₄₀) with imidazole (C₃H₄N₂) and immobilization on chitosan. The synthesized nanocomposite (IMID-KTHPA@CTS) was characterized using FT-IR, ³¹P NMR, XRD, and SEM techniques. The modified heteropolyanion species were highly dispersed on the chitosan polymer matrix. The catalytic activity of IMID-KTHPA@CTS nanocomposite was tested on the CODS process of gasoline and thiophenic model fuels. The obtained results of CODS demonstrated that highest sulfur removal efficiency (97%) could be achieved at 35 °C after 1 h. On the basis of the proposed reaction pathway, the organic sulfur substrates were oxidized catalytically using CH₃COOH:H₂O₂ as an oxidant in the presence of IMID-KTHPA@CTS nanocatalyst. The main factors affecting CODS efficiency, including amount of catalyst, time and temperature, were investigated. Kinetic parameters of oxidation of sulfur compounds, reaction mechanism, and reusability of catalyst are discussed. The excellent reusability of the heterogeneous IMID-KTHPA@CTS nanocomposite was demonstrated for five cycles.

Graphical Abstract

Keywords:

• Heteropolyanion
• chitosan
• phase transfer nanocatalyst
• desulfurization
• gasoline

Disclosure statement

No potential conflict of interest was reported by the authors.