(231a) Modeling of Composite Membranes with Metal Organic Frameworks for High Efficiency Natural Gas Purification

Polymer membranes are a proven technology for large-volume gas separations that have enormous potential in a variety of energy related applications. However, a fundamental tradeoff between throughput and selectivity limits the performance of these membranes. A powerful strategy for overcoming this tradeoff is to create composite materials where filler particles are embedded in a polymer matrix. If the properties of the filler particles can be controlled, large increases in membrane performance are possible. Metal organic framework (MOF) materials offer an exciting prospect as filler particles, since many MOFs are known and the properties of MOFs can be tuned with relative ease. The diversity of known MOFs and polymers makes selection of promising MOF/polymer pairs challenging. We examine the challenge of selecting MOFs for use in high performance composite membranes using a combination of atomistic and continuum modeling. We first validate our models by comparing with experimental data for IRMOF-1/Matrimid membranes. Motivated with the good agreement between our theoretical models and experimental measurements, we study several MOFs including IRMOF-8, IRMOF-10 and Cu-BTC as enabling materials in Matrimid polymers to predict the performance of composite membranes. Finally, we identify a highly selective MOF, Cuhfipbb, which is predicted to greatly enhance the performance of Matrimid and a range of other polymers for carbon dioxide/methane separations. Use of this MOF that was specifically selected to have strong diffusion-based selectivity for carbon dioxide over methane is predicted to create composite membranes with extraordinary performance. The methods demonstrated here will also be of use for materials selection for other large-volume gas separations.