Amino acid spacer-length-regulated ZrW synergy in phosphotungstic acid@MOF hybrids for room-temperature oxidative desulfurization

In order to meet the trend of sulfur-free fuels, it is of great significance to construct catalysts with high-efficiency oxidant activation ability for deep desulfurization at room temperature and low sulfur ratio. In this study, based on the synergistic catalysis of Zr site and W site double active centers in PW/UiO-66, HPW was encapsulated in the main body of UiO-66 by using amino acids with different carbon chain lengths as bridging molecules. The defect-rich catalyst was synthesized by manual grinding method to achieve efficient extraction-catalytic oxidation desulfurization at room temperature. By adjusting the carbon chain length of linear amino acids, the dispersion state of HPW in UiO-66 was optimized, the electron transfer rate between them was improved, and the synergistic effect of Zr W dual active centers was fully utilized. EPR and in-situ infrared characterization showed that hydroxyl radicals and superoxide radicals were generated at the Zr site during the reaction, and the free radicals were converted into tungsten peroxide active oxygen intermediates during the oxidative desulfurization (ODS) process. The regulation of amino acids makes the synergistic effect of Zr W active sites play a full role, which makes the catalyst have excellent catalytic performance. In the ODS system, complete desulfurization (100% removal efficiency) is achieved under mild conditions: ambient temperature, O/S molar ratio of 2, catalyst loading of 1.5 wt%, and a reaction time of 15 min. Furthermore, the catalyst retains nearly unchanged desulfurization performance over nine consecutive ODS cycles, confirming its outstanding reusability. These research results establish a structure–activity foundation for the rational design of highly active, room-temperature deep desulfurization catalysts.