(573f) Hollow Fiber Membrane-Supported Metal-Organic Framework Based Nanopacked Bed for Gas/Vapor Separation

Crystalline metal-organic frameworks (MOFs) with high porosity have high sorption capacities for gases/vapors. Their fragile/pulverulent characteristics have prompted significant efforts to prepare shaped bodies e.g., pellets, granules etc. for adsorption. Such structures lead to loss of surface area among others. A hollow fiber membrane (HFM) based strategy is described here since HFM-based modules are highly preferred for industrial separations due to high surface area provided per unit volume and their easy scalability among others. We employ solvothermal synthesis at 120°C for 18 hr in a DMF-methanol solvent containing reactants NH₂-H₂BDC and ZrCl₄ in a Teflon-lined pressure vessel wherein loose porous Nylon HFMs were inserted, wetted and submerged. After post-reaction cooling, washing and drying, HFMs were potted in a small cylindrical module; nanocrystals of the MOF, UiO-66-NH₂, were synthesized directly inside the submicron pores of hydrophilic HFMs of Nylon 6; MOF microcrystals were synthesized in HFM bores. A 100 ppmv NH₃-containing N₂ stream (50% RH) was introduced into the shell side of the module for separation studies. Removal performance of ammonia from nitrogen will be described. Ammonia appears at module outlet at trace levels at times as high as 800 min. The time/weight values of MOF are as high as 20,000 min/g. The MOFs were regenerated a number of times without performance deterioration. Direct utilization of sorption capabilities of microcrystals and nanocrystals of UiO-66-NH₂ MOF in a high-surface-area adsorber was achieved using a hollow fiber membrane-supported configuration.