"Electrochemical Engineering of a Membrane-free Electrolyzer for the Decarbonized Production and Circular Use of Acid and Base"
Consumption of acid and base drives chemical transformations underpinning myriad industrial processes and emerging carbon management technologies. Conventional production methods normally involve the linear use of reagents, resulting in stoichiometric salt waste, and can be highly energy and carbon intensive. In contrast, electrochemical generation of acid and base from solutions of the neutralized salt enables production using low or zero-carbon power without any stoichiometric waste products. However, conventional electrochemical approaches using ion-exchange membranes (IEMs) have an excessive energy demand, low productive current densities, and poor impurity tolerance. These limitations have prevented adoption of commercial electrochemical systems, necessitating research into new salt-splitting cell designs that may overcome them.
Here I will discuss my work taking on the challenge of salt-splitting electrolysis without IEMs by developing a new cell architecture: the Diaphragm Flow Cell (DFC). First, I will introduce the DFC and the fundamental chemistry and physics of membrane-free electrochemical acid-base production in the context of a low energy demand, permanent carbon dioxide removal process, including a novel bipolar element demonstrated in a 2-cell stack. I will then show using systematic measurements and continuum modeling that modulation of the electrolyte residence time enables generation of > 1 M strong acid and base solutions at high rates and state-of-the-art low energy demand. Finally, I will present an investigation the DFC as a promising technology for the electrified production of slaked lime, a ubiquitous industrial base equivalent.
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