Bifunctionally Hydrophobic MOF-Supported Platinum Catalyst for the Removal of Ultralow Concentration Hydrogen Isotope

Abstract

Water often presents significant challenges in catalysts by deactivating active sites, poisoning the reaction, and even degrading composite structure. These challenges are amplified when the water participates as a reactant and is fed as a liquid phase, such as trickle bed-type reactors in a hydrogen-water isotope exchange (HIE) reaction. The key balance in such multiphase reactions is the precise control of catalyst design to repel bulk liquid water while diffusing water vapor. Herein, a platinum-incorporated metal-organic framework (MIL-101) based bifunctional hydrophobic catalyst functionalized with long alkyl chains (C₁₂, dodecylamine) and further manufactured with poly(vinylidene fluoride), Pt@MIL-101-12/PVDF, has been developed which can show dramatically improved catalytic activity under multi-phase reactions involving hydrogen gas and liquid water. Pt@MIL-101-12/PVDF demonstrates enhanced macroscopic water-blocking properties, with a notable reduction of over 65% in water adsorption capacity and newly introduced liquid water repellency, while exhibiting a negligible increase in mass transfer resistance, i.e., bifunctional hydrophobicity. Excellent catalytic activity, evaluated via HIE reaction, and its durability underscore the impact of bifunctional hydrophobicity. In situ DRIFTS analysis elucidates water adsorption/desorption dynamics within the catalyst composite, highlighting reinforced water diffusion at the microscopic level, affirming the catalyst's bifunctionality in different length scales. With demonstrated radiation resistance, Pt@MIL-101-12/PVDF emerges as a promising candidate for isotope exchange reactions.