Construction of HPW/HP-UiO-66-NH2 Membranes with Tunable Mesopores for Oxidative Desulfurization Applications

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Metal–organic frameworks (MOFs) have promising applications owing to their exceptional tunability and ultrahigh porosity. However, the intrinsic microporosity and powdery form cause large mass transfer resistance, pipeline clogging, and poor recyclability, which greatly restrict their engineering applications. In this work, a hierarchical porous UiO-66-NH2-anchored phosphotungstic acid catalytic membrane (denoted as m-HPW/HP-UNX, where X represents the volume of added water) was successfully fabricated via a cast-coating method using a casting solution blended with HPW/HP-UNX and poly(vinylidene fluoride) (PVDF) solutions. Among them, hierarchical porous HP-UNX was synthesized through template-free competitive nucleation in H2O/acetic acid systems. This solvent-regulated strategy yields HP-UNX nanoparticles smaller than 20 nm, which possess a tunable mesoporous structure and –NH2 sites, making them ideal supports for anchoring bulky phosphotungstic acid (HPW). The resultant m-HPW/HP-UNX catalytic membrane retains the mesoporous structure of HP-UNX and resolves the separation difficulty of the powdery MOFs. Notably, m-HPW/HP-UN9 achieves a desulfurization efficiency of 92%, far exceeding the microporous samples UiO-66-NH2 and m-HPW/UiO-66-NH2. Moreover, the oxidative desulfurization efficiency of the membrane remains approximately 90% after cycles, demonstrating a favorable cycling stability. The strategy of introducing hierarchical pore structures into molding materials provides a feasible pathway for industrial applications of desulfurization catalysts.