Encapsulation of MOF-808 with Keggin-type SiW12 polyoxometalate for highly efficient catalytic oxidative desulfurization

Abstract

The incorporation of polyoxometalates (POMs) into metal-organic frameworks (MOFs) has emerged as a promising strategy for developing high-performance and recyclable catalysts for fuel oil desulfurization. In this study, zirconium-based MOF-808 encapsulating SiW₁₂ and its acid-modified derivative (SiW₁₂-A) were synthesized via a one-pot hydrothermal method. These materials were then evaluated for oxidative desulfurization (ODS) of model sulfur compounds, including benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The SiW₁₂-A@MOF-808(Zr) catalyst achieved a remarkable 97.10 % BT removal within just 30 min under mild conditions (50 °C) using H₂O₂ as the oxidant. Systematic evaluation of reaction parameters revealed the critical role of catalyst dosage, temperature, and oxidant-to-sulfur molar ratio on desulfurization efficiency. Encapsulation of SiW₁₂ within the mesoporous channels of MOF-808 improved active site accessibility and stability, while acid treatment (SiW₁₂-A) further promoted reactive oxygen species generation. The catalyst demonstrated excellent structural stability and recyclability over six consecutive cycles without significant loss of activity. This study presents a facile synthesis approach for POM@MOF composites and highlights their practical potential in clean fuel production through efficient ODS.