Separation of nitrogen via Group V metallic membranes for post-combustion carbon capture

摘要

Reducing carbon dioxide (CO2) in the atmosphere is the key to mitigating global climate change and one option is carbon capture from coal- or natural gas-fired power plants. A fundamental challenge associated with CO2 capture is its low concentration in the emission source for economically viable capture. A recent study by House et al. show that there is a strong correlation between the dilution of the gas to be separated to the second-law efficiency of the separation process. Therefore, instead of tackling the separation of CO2 at low concentration, focus on the separation of the gas in higher concentration would be beneficial if it is possible. If CO2 can be separated in the retentate stream where still the feed pressure is maintained, there would be also saving in terms of the compression energy for pipeline transport. In general, the main component of post-combustion flue gas is N2 at approximately 70 - 80%. If we can selectively capture N2, we can take advantage of the driving force of the higher N2 concentration. Ideally, selective N2 separation could be beneficial in diverse applications such as air separation technology and ammonia (NH3) synthesis. In this study, pure vanadium (V) metallic foils have been investigated as membrane materials for selective N2 separation. N2 can be catalytically dissociated on metal surfaces and permeate through the metallic membrane in its atomic form via a solution-diffusion mechanism. This work will provide fundamental knowledge toward the design of a metallic membrane with optimal selectivity and permeability of N2 for post-combustion CO2 capture.