High Efficiency, High Performance Metal-Organic Framework (MOF) Membranes in Hollow Fibers and Tubular Modules

A reactor cell for measuring gas and liquid permeation is disclosed. A hollow fiber is supported by and sealed into a first hole and a second hole of the reactor module. The first and second ends of the hollow fiber are sealed with a sealing solution. Methods for making and using the reactor cell are also disclosed. As made and used, the reactor cell further comprises a molecular sieving membrane that is uniform and free of defects grown on an inner bore surface of the hollow fiber

Apparatus, Methods and Systems For Fabricating Thin Nanoporous Membranes

Embodiments of the present disclosure provide apparatuses, methods and systems for scalable fabrication of thin, nanoporous membranes useful in industrial applications. One embodiment of the present disclosure provides a molecular separation device configured to efficiently separate molecular species. In this particular embodiment, porous hollow fibers form a supporting scaffold for synthesis of a molecular organic framework (MOF) membrane. The MOF membrane may be synthesized on the inner or outer porous hollow fiber surface as well as within the porous fiber wall. Embodiments of the present disclosure provide a variety of methods for producing the aforementioned molecular separation devices as well as methods for producing MOF membranes

Mixed-linker ZIF materials and ZIF/polymer hollow fiber membranes for hydrocarbon separations

I demonstrated the effective pore size can be continuously and drastically tuned using mixed-linker ZIFs containing two types of linkers, allowing their use as a more general molecular separation platform. This remarkable behavior was illustrated by adsorption and diffusion measurements of hydrocarbons, in mixed-linker ZIF-8-90 materials with a large range of crystal sizes (338 nm to 120 µm). I also demonstrate significant new advances in mechanistic understanding and engineering of support properties for interfacial microfluidic processing techniques in hollow fibers and the use of this understanding to fabricate high-performance ZIF-8 membranes for propylene and hydrogen separations. We also made a progress towards a more generalized ZIF membrane fabrication platform by extending IMMP to macroporous carbon hollow fiber supports. Here, I overcame several additional hurdles for practical MOF membrane fabrication, including address the problems of polymer hollow fiber swelling issues and solvent limitations. I showed the versatility of IMMP by modifying it for the successful fabrication of selective ZIF-90 and ZIF-8 membranes on the inner surface of carbon fibers. Finally, Detailed membrane performance was tested with various techniques.Ph.D

ZIF-8 Membranes via Interfacial Microfluidic Processing in Polymeric Hollow Fibers: Efficient Propylene Separation At Elevated Pressures

Propylene/propane (C3H6/C3H8) separations are performed on a large scale by energy-intensive distillation processes. Membranes based on metal-organic framework (MOF) molecular sieves, such as zeolitic imidazolate framework-8 (ZIF-8), offer the potential to perform these separations at considerably lower cost. However, the fabrication of scalable ZIF-8 membranes with high performance at elevated pressures and temperatures is challenging. We report the fabrication of high-quality ZIF-8 hollow fiber membranes in engineered polymeric hollow fibers via the interfacial microfluidic membrane processing (IMMP) technique. Control of fiber microstructure, as well as optimization of IMMP conditions, allow us to achieve a C3H6/C3H8 separation factor of 180 (at 1 bar and 25 °C), which remains high (60) at 120 °C. Furthermore, high-pressure operation of these membranes was investigated. Detailed permeation measurements indicate excellent suppression of defects at higher pressures up to 9.5 bar, allowing a C3H6/C3H8 separation factor of 90 at 9.5 bar. The membranes also display a 4-fold increase in flux at 9.5 bar as compared to operation at 1 bar. The long-term stability of the ZIF-8 hollow fiber membranes is demonstrated by continuous operation over a month without loss of C3H6 permeance or selectivity

Fluidic Processing of High-Performance ZIF-8 Membranes on Polymeric Hollow Fibers: Mechanistic Insights and Microstructure Control

Recently, a methodology for fabricating polycrystalline metal-organic framework (MOF) membranes has been introduced-- referred to as interfacial microfluidic membrane processing -- which allows parallelizable fabrication of MOF membranes inside polymeric hollow fibers of microscopic diameter. Such hollow fiber membranes, when bundled together into modules, are an attractive way to scale molecular sieving membranes. The understanding and engineering of fluidic processing techniques for MOF membrane fabrication are in their infancy. Here, a detailed mechanistic understanding of MOF (ZIF-8) membrane growth under microfluidic conditions in polyamide-imide hollow fibers is reported, without any intermediate steps (such as seeding or surface modification) or post-synthesis treatments. A key finding is that interfacial membrane formation in the hollow fiber occurs via an initial formation of two distinct layers and the subsequent rearrangement into a single layer. This understanding is used to show how nonisothermal processing allows fabrication of thinner (5 µm) ZIF-8 films for higher throughput, and furthermore how engineering the polymeric hollow fiber support microstructure allows control of defects in the ZIF-8 membranes. The performance of these engineered ZIF-8 membranes is then characterized, which have H2/C3H8 and C3H6/C3H8 mixture separation factors as high as 2018 and 65, respectively, and C3H6 permeances as high as 66 GPU

Fluidic Membrane Processing: Fluidic Processing of High-Performance ZIF-8 Membranes on Polymeric Hollow Fibers: Mechanistic Insights and Microstructure Control (Adv. Funct. Mater. 28/2016)

On page 5011, S. Nair and co‐workers show that metal‐organic framework membranes, grown by non‐isothermal fluidic processing techniques on the inner surfaces of polymeric hollow fiber supports, efficiently separate molecular mixtures such as propylene from propane by size- and shape-selective sieving through their subnanometer pores

Highly Tunable Molecular Sieving and Adsorption Properties of Mixed-Linker Zeolitic Imidazolate Frameworks

Nanoporous zeolitic imidazolate frameworks (ZIFs) form structural topologies equivalent to zeolites. ZIFs containing only one type of imidazole linker show separation capability for limited molecular pairs. We show that the effective pore size, hydrophilicity, and organophilicity of ZIFs can be continuously and drastically tuned using mixed-linker ZIFs containing two types of linkers, allowing their use as a more general molecular separation platform. We illustrate this remarkable behavior by adsorption and diffusion measurements of hydrocarbons, alcohols, and water in mixed-linker ZIF-8_<i>x</i>-90_{100–<i>x</i>} materials with a large range of crystal sizes (338 nm to 120 μm), using volumetric, gravimetric, and PFG-NMR methods. NMR, powder FT-Raman, and micro-Raman spectroscopy unambiguously confirm the mixed-linker nature of individual ZIF crystals. Variation of the mixed-linker composition parameter (<i>x</i>) allows continuous control of <i>n</i>-butane, <i>i</i>-butane, butanol, and isobutanol diffusivities over 2–3 orders of magnitude and control of water and alcohol adsorption especially at low activities