SUMMARY

Natural gas has become increasingly important as a fuel source with a lower environmental impact; therefore, there is a growing need for scalable natural gas purification systems with smaller footprints. Current industrial purification systems are based on absorption, membrane separation, or adsorption techniques and each of these technologies require large capital costs or suffer from scalability issues. Adsorption-based separation techniques are categorized into pressure swing adsorption (PSA) and temperature swing adsorption (TSA). Among adsorption-based gas purification, the PSA has typically been preferred over the TSA due to ease of operation and reliability. TSA processes have not been commonly used for industrial gas separation due to the difficulty in heating the low thermal conductivity adsorbent material to desorb impurities and regenerate the adsorbent. However, the high heat and mass transfer coefficients possible with microchannels opens the possibility of using the TSA process for gas purification.
The proposed work investigates the fluid mechanics and coupled heat and mass transfer processes within a microchannel monolith with a polymer matrix coated with adsorbent along the inner walls of the microchannels to be used for TSA-based gas separation. The concept involves separation of carbon dioxide from methane by passing the feed gas through microchannels, followed by a sequential flow of desorbing hot liquid, cooling liquid, and purge gas through the same microchannels. It is found that for selected operating conditions and geometries, the process shows merit when compared to current technologies. Spatially and temporally resolved analyses are conducted to assess these processes and select optimal configurations and process parameters. Experimental validation will follow; wherein gas separation in adsorbent laden microchannels is analyzed using mass spectrometry. The combination of measurements and analyses is used to develop validated models and design guidance for TSA processes for gas separation.