Gas separations are a key requirement for many of today's industrial operations and are important for environmental safety, human health, and energy production. For example, carbon capture, which is essentially a separation of carbon dioxide from nitrogen resulting from the combustion of natural gas or coal in a power plant, will avoid emission of carbon dioxide into the atmosphere. Other important gas separations include recovery of hydrogen for industrial use, recovery of noble gases such as xenon from air, and separation of key light gas petrochemicals such as propane and propylene. In this project, a new gas separation technology - Supercapacitive Swing Adsorption - will be researched and designed. The project's approach will use capacitive energy to achieve the gas separation. This form of energy has the advantage that it can be recovered with minimal losses. As a consequence, the technique is promising to achieve gas separations with lower energy consumption compared with currently used methods. The energy efficiency of gas separations processes is very important for economic viability. In addition, Supercapacitive Swing Adsorption has a potential lower environmental footprint since it requires non-toxic, environmentally friendly chemical solvents and carbon-based materials as the adsorbent. Supercapacitive Swing Adsorption has the potential to be applicable to several important industrial gas separations. In this project the PI will focus on the separation of carbon dioxide from nitrogen because of the extreme importance of carbon capture and sequestration.
In contrast to conventional pressure and temperature swing adsorption processes, Supercapacitive Swing Adsorption offers an approach for full selectivity towards a targeted gas mixture component. In the process, the sorbent itself is reversibly altered by capacitive charge and discharge leading to a change in gas adsorption behavior. An electric double layer is formed and the targeted component is adsorbed in/on the electrode. Capacitive charge and discharge is a thermodynamically reversible process that can be operated with high energy efficiency, since a continuous current is not used and the gases are adsorbed similar to physisorption energetics. Supercapacitive Swing Adsorption modules will be tested for their performance in the separation of carbon dioxide from nitrogen as an example of carbon capture. The modules will allow for charge and discharge under continuous gas flow. The primary performance parameters of investigation will be energy efficiency, purity of the produced gas, gas adsorption capacity, and adsorption and desorption kinetics. To maximize the energy efficiency, the team will design electrodes with minimal internal resistance. The shape and morphology of the electrodes will be optimized with regard to charge and discharge kinetics as well as gas adsorption and desorption kinetics. To maximize the gas adsorption capacity the PI will perform experiments with increased voltage, explore new sorbent materials as electrodes, and test alternative electrolytes.
