Material and Engineering Assessments of Electrochemical Processes for Carbon Capture Technology

Integrating carbon capture technology with large source carbon emitters is necessary in the very near future to mitigate the contribution of anthropogenic CO₂ emissions to climate change and global public welfare. However, the implementation of this technology with current separation approaches is a challenging task due to the scale at which CO₂ is produced and the energy consumption to drive the separation process. Thermal-swing separation processes based on chemical sorbents show potential for facilitating large-scale CO₂ capture; however, the energy efficiency in the current thermal-swing processes is unacceptable for their implementation. To overcome this problem, new approaches to gas separation have to be developed.

Electrochemically mediated processes are proposed to facilitate CO₂ capture from a dilute gas mixture by exploiting the significant changes in molecular affinity of certain sorbents for CO₂ molecules when they undergo an electrochemical cycle. The proposed process has the potential for reducing the parasitic energy of the current solvent-based absorption operations since it does not require significant temperature swings to regenerate the sorbents. Molecular optimization of the candidate materials is required to enhance their chemical stability, and implementation requires efficient electron transfer operations for rapid electrochemical switching. This materials optimization is achieved through a combination of electrochemical experiments and quantum chemical simulations. The results from the potentiostatic study of the promising sorbent candidates are used to elucidate the energy required for CO₂ separation from a dilute gas mixture using the proposed technology. A general engineering framework of an electrochemical separation unit is developed to elucidate several key design aspects and parameters that relate the process configuration and properties of the material properties to the energy efficiency of the processes. We conclude with a discussion of the general concepts and the advances needed in both the materials and the engineering aspects for their successful implementation as carbon capture technology of the future.