Linker-driven tuning of pore structure and acidity in Zr-MOFs for paraoxon-methyl hydrolysis and efficient oxidative desulfurization

Abstract

Background: Zirconium-based metal-organic frameworks are promising candidates for catalytic applications due to their high structural stability, tunable porosity, and acidity. However, the influence of organic linkers on their acid site distribution, pore structure, and catalytic activity, particularly in hydrolysis and oxidative desulfurization reactions, has not been fully explored.

Methods: A series of Zr-MOFs was synthesized using a microwave-assisted solvothermal method at 100 °C for 30 minutes, reducing reaction times by 20–50 times compared to conventional solvothermal approaches. Structural, textural properties, acidity and defect content were characterized using TEM, BET, NH3-TPD, FTIR-CD3CN, ESR and XPS. The catalytic activity was evaluated for the hydrolysis of paraoxon-methyl (PM) and the oxidative desulfurization of dibenzothiophene (DBT) under mild conditions. The ODS mechanism of DBT and hydrolysis mechanism of PM are proposed based on the identified degradation products by GC–MS/LC-MC, nuclear magnetic resonance and the role of the Lewis acid sites.

Significant findings: Organic linker variation significantly affected the pore size (0.83–3.68 nm), surface area (1332–1762 m2 g-1), and acid site distribution. Zr-BTC exhibited the highest Lewis acidity (0.311 mmol g-1) and defect content, achieving complete PM hydrolysis in 2.5 min and 100 % DBT removal within 30 min. Catalytic efficiency strongly correlated with Lewis acid site density modulated by the choice of linker.