(475a) Hybrid Membrane-PSA System for Efficient Oxygen Generation for Transportable, Modular Gasification Systems

Modular gasification systems need new low capital and operating cost approaches for the separation of O₂ from air to produce high-purity O₂ (>97%). Production of O₂ with large-scale cryogenic distillation is costly and not scalable to small- to commercial-scale systems. The feasibility of concentrating O₂ from air using a combination of targeted mixed matrix membranes (MMMs) with a process-intensified, process-integrated pressure swing adsorption (PSA) system was experimentally determined. Pre-concentrating O₂ with MMMs allows the integrated PSA system to generate high-purity O₂ with smaller PSA units, faster cycle times, and reduced power requirements to minimize the overall costs. High-capacity O₂ sorbent materials, commercial adsorbents, and O₂-selective adsorbents such as cerium-exchange zeolite, titanosilicates, and cerium-exchanged zeolite X with strontium were tested and characterized Adsorbents were characterized by BET analysis, energy-dispersive X-ray (EDX) spectroscopy, X-ray power diffraction (XRD), and equilibrium adsorption isotherm measurements. Porous asymmetric MMMs with high selectivity and permeability were synthesized using glassy polyimides, polyether sulphone (PES), and polyvinyl acetate and then modified with a thin layer of a zeolite or silicate nanomaterial. The nanomaterials were combined with a high permeability glassy polymer such as Poly (1-trimethylsilyl-1-propyne) (PTMSP) to form an asymmetric membrane onto a porous substrate (e,g, PES). A range of inorganic fillers (e.g., clays, zeolites, aluminosilicates) were used to evaluate selectivity and permeability. The effects of the membrane thickness, porosity, inorganic material loading, and operating conditions were determined. Lastly, a pilot-scale PSA system was operated using an O₂-enriched stream representative of the membrane-based concentrator to demonstrate the combined membrane-PSA approach. The incoming, O₂-enriched air was varied to determine the effects of O₂ concentration, temperature, pressure, and other process parameters on the total power and energy for operation, separation efficiency, and effluent gas O₂ concentration.