D-alanine-bridged phosphotungstic acid/UiO-66 hybrids as efficient catalysts for oxidative desulfurization of fuels

The development of highly active catalysts is crucial for oxidative desulfurization (ODS) to meet the growing demand for sulfur-free fuels. In this study, a defect-rich composite catalyst UiO-DAlaPW was successfully synthesized via mechanochemical grinding, wherein phosphotungstic acid (HPW) was encapsulated within a defect-engineered UiO-66 framework, utilizing D-alanine (DAla) as a bridging molecule. The synthesized catalyst, UiO-DAlaPW, significantly enhances the utilization efficiency of hydrogen peroxide (H 2 O 2 ). In the model oil ODS system, the material exhibited exceptional catalytic performance: achieving deep desulfurization at room temperature within merely 5 min under conditions of extremely low acetonitrile cosolvent usage and a low oxidant/sulfur (O/S) ratio, accompanied by remarkably high H 2 O 2 utilization efficiency. Moreover, the catalyst maintained high desulfurization efficiency even in the absence of acetonitrile. Characterization by XRD, FT-IR, TGA, and XPS confirmed the successful encapsulation of HPW within the UiO-66 framework. Mechanistic studies revealed a significant synergistic effect between UiO-66 and HPW. The effective cooperation of the two active sites, namely Zr in UiO-66 and PW, significantly enhances the catalytic performance, contributing to superior oxidative desulfurization activity.