Design of hierarchically porous Zr-MOFs with reo topology and confined PMA for ultra-efficient oxidation desulfurization

• Published in: Molecular catalysis 2023-03, Vol.538, p.113007, Article 113007
• Main Authors: Zong, Meng-Ya, Zhao, Zhe, Fan, Cun-Zheng, Xu, Jun, Wang, Dan-Hong
• Format: Article
• Language: English
• Subjects: Hierarchically porous MOFs; Oxidative desulfurization; Reo topology; Zr-OH2 defect sites
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2023.113007

•Hierarchically porous Zr-mofs (H-UiO-66-X) were synthesized through an in situ self-assembly template strategy.•PMA/H-UiO-66–1 presented well-confined PMA in the missing Zr6O8 cluster defect with reo topology structure and PMA Keggin structure, which exhibited excellent activity in the ODS reaction.•Titrations are successfully used for quantifying defect sites resulting from either missing Zr6O8 clusters or missing linkers. It is challenging but desirable to synthesize hierarchically porous MOFs (HP-MOFs) with well-defined topology. Herein, a series of HP-Zr-MOFs (H-UiO-66-X) with different topologies were synthesized through an in situ self-assembly template strategy. Further, H3PMo12O40 (PMA) was dispersed within H-UiO-66-X to illustrate the confinement effect of HP-MOFs on PMA as ultra-efficient ODS catalysts. Potentiometric acid–base titration is used to evaluate three typical types of Brønsted acid protons (μ3–OH, Zr-OH2, and Zr-OH) presented in the nodes of defect HP-MOFs according to their different pKa values (∼3, ∼6 and ∼8). By quantifying the amount of defect sites (Zr-OH2 and Zr-OH) resulting from either missing Zr6O8 clusters or missing linkers in the HP-MOFs, the information about the true topology of HP-MOFs is provided. The Zr-OH2 defects are correlated to missing Zr6O8 cluster and the Zr-OH defects are related to missing linkers. The loaded PMA molecules mainly occupy the Zr-OH2 defect sites by the substitution of H2O molecules and still maintain the Keggin structure. The results give deep insight on the structure-activity relationship for PMA confined in HP-Zr-MOFs with clear topologies. [Display omitted]