Matrimid®/ZIF-8 hollow fiber mixed matrix membranes for hydrogen recovery from industrial waste streams

Abstract

The development of efficient separation technologies to recover hydrogen from industrial waste streams plays an important role to satisfy the increasing demand for hydrogen. In this work, mixed matrix hollow fiber membranes were synthesized by incorporating an inorganic filler (ZIF-8) with molecular sieve properties, into a Matrimid® polymer matrix. The membranes were tested under conditions that reproduce real industrial processes, focusing on H₂/CO₂ separation. Addition of 5 wt% ZIF-8, whose well distribution along the fiber was confirmed by SEM and EDX analysis, resulted in a significant improvement in H₂ permeance (30.5 GPU) compared to pristine Matrimid® (16 GPU) at 30 °C. Moreover, selectivity was improved by 67 % reaching values of 3.3 and 41 for H₂/CO₂ and H₂/bulk compounds at 30 °C. The increase in the separation performance is attributed to the molecular sieve effect of ZIF-8 together with the increase of the free volume due to the inclusion of the filler in the polymer matrix, enhancing H₂ flux over the other gases. Moreover, the hollow fiber membranes were tested under varying conditions of pressure, temperature and feed composition, including multicomponent streams that represent real process conditions, confirming promising results helping to scale up mixed matrix hollow fiber membranes.