Activating oxidative desulfurization and acetalization performance over metal-organic frameworks by introducing Fe single-atom under solvent-free conditions

The utilization of green synthesis techniques for the fabrication of multipurpose single-atom catalysts offers new opportunity to enable a single catalyst to be employed in multiple target applications. Herein, we show a one-pot green strategy for in-situ anchoring of Fe single atom (Fe₁) onto the Zr-oxo clusters of UiO-66(Zr) via the formation of Fe–O–Zr bonds without the use of any solvent. The introduction of Fe₁ endows the UiO-66(Zr) supporter with significantly enhanced catalytic performance in oxidative desulfurization (ODS) and acetalization reactions. 1000 ppm sulfur of thioanisole, dibenzothiophene or 4,6-dimethyldibenzothiophene can be completely removed within 12, 15, or 20 min at 40 °C during the ODS reaction, and 11.2 mmol benzaldehyde is converted to (dimethoxymethyl)benzene within 2 min at 25 °C during the acetalization reaction. The turnover frequency values over Fe₁/UiO-66(Zr) reach 545.0 h⁻¹ at 40 °C for ODS (29.3 and 362.3 times higher than FeCl₃ and UiO-66(Zr) supporter), and 2829 h⁻¹ at 25 °C for acetalization, exceeding most reported catalysts. Density functional theory calculations confirm that the anchored Fe₁ in Fe₁/UiO-66(Zr) not only exhibits an exceptionally strong adsorption capacity for H₂O₂ but also facilitates the decomposition of absorbed H₂O₂ into ·OH radicals, which plays a critical role in determining the reaction efficiency. This work provides a sustainable one-pot green approach for decorating multi-purpose single-atom catalysts (SACs) on metal-organic frameworks to enhance their redox and acid catalytic activities for diverse reactions.