Advancements in reactive carbon capture

The electrochemical CO₂ Reduction Reaction (CO₂RR) converts waste CO₂, water, and electricity into chemicals typically derived from fossil fuels. However, most CO₂ capture and conversion processes rely on pure, gaseous CO₂ feedstocks that are energy-intensive to produce and limit scalability. This thesis investigates reactive carbon capture, a CO₂ capture and conversion process that uses liquid alkaline capture solutions as the feedstock, avoiding the energy costs associated with gaseous CO₂. In these solutions, CO₂ is captured as bicarbonate and carbonate ions. These ions can react with electrochemically generated protons inside the reactive carbon electrolyzer to produce the required gaseous CO₂ for CO₂RR. Additionally, CO₂RR in reactive carbon electrolyzers can regenerate the CO₂ capture solution. This capture solution regeneration combined with CO₂ upgrading integrates CO₂ capture and conversion into a closed loop, where the capture unit generates the feedstock for the electrolyzer, and the electrolyzer generates the feedstock for the capture unit. The objective of this thesis is to establish a clear case for reactive carbon capture as a viable CO₂ capture and conversion process for industrial scale-up. First, I analyze the fundamental chemistry of reactive carbon capture to identify the most practical CO₂RR product for closed-loop operation. I introduce electron–alkalinity efficiency, a metric linking electron consumption to capture solution regeneration, and show that CO is the optimal target product. Next, I demonstrate the use of rationally designed amine CO₂ capture promoters that enhance CO₂ capture rates without sacrificing electrolyzer selectivity. Finally, I use a self-driving laboratory to optimize electrolyzer operating conditions, revealing a tradeoff between CO production rate and CO₂ utilization that can be tuned through operational control.