(Invited) Electro-Swing Adsorption for CO2 Emissions Mitigation – from Concept to Start-up

Abstract

The increasingly devastating effects of changing climate patterns can be attributed largely to global warming through the continuing accumulation in the environment of anthropogenic greenhouse gases such as carbon dioxide. While reduction of CO2 emissions at relatively concentrated (4-20%) point sources is a crucial component of mitigation strategies for the abatement of the CO2 impact on global temperature rise, it has become increasingly evident that direct removal of accumulated CO2 (at 420ppm, 0.042%) from the environment will also be needed if we wish to limit the global temperature rise by the turn of the century to less that 2°C. Legacy carbon capture processes rely on thermal swings, with elevated temperatures required to break the chemical bonds formed during the cooler capture stage to liberate the CO2 as a pure product stream and regenerate the sorbent. There has recently been a surge of interest in using electrochemically mediated processes for carbon capture and release which can be operated isothermally, are modular, with easy scale out, and can be installed without need for complex heat integration processes. Moreover, they can use renewable and other non-carbon energy resources.In this presentation, we will trace the development of an electrochemical swing adsorption approach for the capture of CO2, originally conceived in 2015, through to the incorporation of a start-up, Verdox, in 2019 to exploit the technology in both point source and direct air capture applications. This approach exploits the ability of certain redox species, such as quinones, to bind strongly with CO2 when in a reduced state, but which have no affinity for the acid gas when oxidized. The activation by reduction and subsequent de-activation by oxidation of the capture agent can be achieved electrochemically with the redox species either in solution or immobilized on electrode surfaces; it is this latter strategy that we will discuss here. The challenges in electrode development, including the identification and economical synthesis of appropriate redox species for the binding of the CO2, and enhancement of chemical and physical robustness with acceptable uptake kinetics, will be discussed, with projections on the future introduction to industrial applications.