Boosting Hydrogen Transport in Mixed Matrix Membranes Through Continuous Spillover Via Pd-Functionalized MOF Gel Networks

Abstract

Membrane-based gas separation offers notable energy efficiency benefits for hydrogen purification, yet it is often hindered by the inherent trade-off between permeability and selectivity. To address this challenge, a novel mixed matrix membrane (MMM) design is presented to boost H₂ separation performance via continuous hydrogen spillover mechanisms for the first time. The MMM incorporates a palladium-functionalized ZIF-67 gel (Pd@ZIF-67 gel) network into a polymer of intrinsic microporosity (PIM-1) matrix. The ZIF-67 gel network serves as a uniform dispersion medium for palladium nanoparticles (Pd NPs), thereby generating a multitude of active sites. These exposed sites, in conjunction with the microporous structure of ZIF-67, facilitate hydrogen dissociation and establish a continuous hydrogen spillover pathway throughout the membrane. This synergistic MMM design leads to substantial improvements in both hydrogen transport and selectivity. At an optimal loading of 28 wt% Pd@ZIF-67 gel, the MMMs exhibit a H₂ permeability of 3620 Barrer and a remarkable 417% enhancement in H₂/CH₄ selectivity (24.9), surpassing the 2008 upper bound. This approach paves the way for the development of advanced materials tailored for gas separation applications.