The broader impact/commercial potential of this project is to strengthen the competitive position of membrane companies in the natural gas treatment market. This would also allow users to benefit from the ease of processing and environmental advantages offered by membranes at substantially reduced costs. Natural gas processing to remove carbon dioxide and other contaminants is the largest industrial gas separation application. At present, membrane processes have 10% of the U.S. market of $1.2 billion. Amine absorption technology is the current industry standard. But membranes provide both cost and environmental advantages over amine absorption. The U.S. Energy Information Administration projects a rapid rise in domestic natural gas production over the next two decades. The expanding natural gas market presents a timely opportunity for membrane companies to acquire a greater market share. Today's membranes lose too much methane with the removed carbon dioxide. If more selective membranes could be made, the process would be much more widely used. This Small Business Innovation Research Phase I Project work is targeted at developing advanced membranes for natural gas purification. At the high pressures and high CO2 concentrations in natural gas processing, the CO2/CH4 selectivity of commercial cellulose acetate membranes is 12 to 15. This modest selectivity has limited the application of membranes. Better membranes with higher CO2/CH4 selectivities are required. The objective of the proposed project is to achieve a mixed-gas CO2/CH4 selectivity of 30 and CO2 permeance of 400 gpu, which would be more than twice the levels of separation currently available from cellulose acetate membranes. To achieve this goal, we propose to use polymer/metal-organic framework (MOF) hybrid materials to develop advanced membranes for CO2/CH4 separation. Molecularly tailored MOFs will be added into suitable polymer matrices, to enhance CO2/CH4 diffusivity selectivity or CO2/CH4 solubility selectivity. This project will make thin-film composite membranes using different polymer/MOF combinations and evaluate the CO2/CH4 separation properties. Successful development of polymer/MOF-membranes can significantly reduce operating cost by 30 percent and capital cost by 40 percent. This could be transformative in natural gas processing. The proposed technology can potentially be extended to other applications such as hydrogen/carbon dioxide and olefin/paraffin separations.
