Executive Summary
Processing natural gas is the largest industrial application of gas separation membranes. Membranes occupy 10% of the ~$5 billion worldwide annual market for new natural gas separation equipment, with amine absorption accounting for most of the rest. While widely used, amine systems suffer from corrosion, complex process design, and equipment often unsuitable for offshore gas processing platforms. Amine systems are also less efficient than membranes at high CO2 concentrations. Current membrane systems are most commonly based on asymmetric cellulose acetate polymers and suffer from lower CO2/CH4 selectivity and lower fluxes than are needed for more general adoption. Low selectivity means that such systems are often multi-stage, requiring expensive recompression of exhaust gas to extract more hydrocarbon product from it or resulting in greater losses of hydrocarbon product to waste streams. Low fluxes impact the overall size and cost of membrane equipment to treat a given quantify of natural gas. This project will prepare and characterize novel nanocomposite membranes based on recently discovered metal organic framework (MOF) materials and related nanoparticles having outstanding separation properties for removal of acid gases (e.g., CO2) from natural gas. The project aims to demonstrate advanced nanocomposite membranes with much higher flux and selectivity than commercial state-of-the-art membranes when separating CO2 from mixtures with CH4 and mixtures containing aromatic contaminants. Membrane systems based on such membranes would be several times smaller than existing systems to process comparable amounts of gas and lower the hydrocarbon losses, thereby increasing energy efficiency and minimizing emissions/waste.
Potential Impact
Relative to conventional cellulose acetate (CA) membranes, the proposed MOF membrane materials would have improved separation properties, excellent stability in process environments, and the ability to be manufactured as thin-film composite or asymmetric membranes. This would markedly reduce the size and weight of the systems. It will also eliminate the need for multi-stage processes, simplifying the process markedly and decreasing emissions/waste and energy consumption per unit mass of pipeline-grade natural gas produced. The proposed nanocomposite membranes systems will have 10x higher flux and will be 10x smaller and lighter (important for offshore applications on platforms) with hydrocarbon waste/emissions reduction by 50%.
Resources
The University of Texas at Austin brings extensive experience in gas separation membranes as well as asymmetric hollow fiber and flat sheet membrane manufacturing capabilities for production of the prototype membrane. Commonwealth Scientific and Industrial Research Organization (CSIRO) has pioneered the continuous flow production of nanoporous materials and have reported record efficiencies. They also have access to all the requisite chemical synthesis and characterization facilities, as well as gas permeation testing facilities for scale up and pilot testing.
