Electrochemically-modulated processes are proposed as a potential next generation CO2 separation technology for the mitigation of environmental and climatic problems associated with large-scale carbon emissions. These isothermal separation processes utilize electrical energy to facilitate effective CO2 capture and regeneration under more benign, isothermal conditions than in traditional thermal-based chemical scrubbing processes. Two types of electrochemical-swing separators are developed, viz. electrochemically-mediated membrane separation (ECMS) and electrochemically-mediated gas scrubbing (ECGS) processes, which have the potential for reducing the parasitic energy of the current solvent-based absorption processes since they do not require significant temperature swings to regenerate the sorbents. Molecular optimization of the redox sorbents is required to enhance their chemical stability, and implementation requires efficient electron transfer operations for rapid redox switching.The ECMS process is a facilitated transport membrane operation that utilizes electrical energy to create a potential gradient to facilitate effective CO2 capture and regeneration. We exploit the significant changes in binding affinity of quinones for CO2 when these carriers undergo changes in their redox state. The quinones exhibit desired selectivity and capacity for CO2 capture in one redox state, with a significant decrease in CO2 binding affinity when its redox state is altered. The ECGS process combines the advantages of the activation of redox-active molecules and the traditional gas sorption technology, and offers the advantage of decoupling the electrochemical process from the gas absorption operation, which could significantly simplify equipment design and implementation of electrochemically-mediated separation processes.In this presentation, we will discuss the general principles of the two proposed technologies in terms of the relevant thermodynamic and kinetic processes, and provide an assessment of the technological and economic implications of these electrochemical approaches for carbon abatement.

Electrochemically-mediated gas separation processes for carbon abatement

243rd National Meeting (2012)

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