Highly Efficient and Reusable Denitrogenation Adsorbent Obtained by the Fluorination of PMA-MIL-101

Abstract

A simple but efficient strategy to improve the ability of adsorptive denitrogenation (ADN) of MIL-101(M101) was studied by the in situ encapsulation of phosphomolybdic acid (PMA) and the subsequent purification of the as-synthesized product by the NH4F solution. After the NH4F treatment, the vast majority of PMA was removed, loss of organic ligand (BDC) was observed, and the fluorination of the hydroxyl group in the M101 structure occurred. The ADN activities of the Cr-MOF matrix composites before and after fluorination were studied in detail. The rest of PMA interacts strongly with M101 and assists the ADN activity. Coordination unsaturated metal sites (CUS) in M101 are formed after fluorination and also contribute to ADN activity. Further, fluoride anions replace most of the hydroxide groups in M101, which can promote the ADN of quinoline (QUI) and indole (IND) through an acid–base interaction and N-atom coordination with the CUS in M101. P-M101-F 5% exhibits the highest adsorptive capacity and excellent regeneration ability. Special emphasis in this work is placed on structure modulation (including PMA doping, CUS creation, and fluorination) of M101 for enhancing ADN activity, which provides a useful scaffold for future research in the rational design of MOF-based ADN catalysts.

Amphiphilic Catalysts Comprising Phosphomolybdic Acid Fastened on MIL-101(Cr): Enabling Efficient Oxidative Desulfurization under Solvent-Free and Moderate Reaction Conditions

“…The Mo 3d core-level spectrum is divided into two isolated peaks placed around 232.6 and 235.8 eV (Figure c), attributing to Mo 3d 5/2 and Mo 3d 3/2 , respectively, with a spin–orbit split of 3.2 eV. This suggests that the molybdenum element in the catalyst is presented in the hexavalent form, and it also implies that the POM-IL remains relatively stable during the loading procedure. , Similarly, peaks of trivalent Cr 2p are observed at 586.3 and 576.8 eV (Figure d), relating to Cr 2p 1/2 and Cr 2p 3/2 , respectively …”