Electroreduction of Carbon Dioxide to Syngas: From Concept to Pilot Plant

Abstract

Increasing evidence suggests that the unwanted effects of climate change, including global warming, rising sea levels, and erratic weather patterns are the result of the increasing atmospheric concentrations of carbon dioxide and other greenhouse gasses. Further development and integration of renewable but intermittent energy sources such as solar and wind, as well as enhancing energy efficiency in buildings and transportation applications will be critical to significantly reduce global CO2 emissions. An alternative strategy to reduce CO2 emissions is to use CO2as a feedstock in the production of chemicals. The electrochemical reduction of CO2 into useful chemicals such as formic acid, carbon monoxide (CO), hydrocarbons, or alcohols has started to receive significant attention, both in academia and industry. Most research efforts over the last decade have focused on the development of increasingly better cathode catalyst for the efficient electrochemical reduction of CO2 to formic acid, CO, and other products. A few companies are trying to commercialize CO2 to formic acid, but the world market for formic acid is small. The bigger opportunities lie in conversion of CO2 to CO or syngas, as that product feds directly into the well-known Fischer-Tropsch for the production of chemical and fuels. Our group and others have advanced electrolysis of CO2to CO to the level where companies have started to look into scale up, including testing of the process in a pilot plant. This presentation will summarize the development of suitable cathode catalysts for selective CO2 to CO conversion, but also point out the importance of developing suitable gas diffusion electrodes (given that the CO2 feed is a gas), and the tuning of the electrolyte composition to maximize performance. Furthermore, this presentation will cover the importance of optimizing the anode side, typically the oxygen evolution reaction, in order to achieve much better energetic efficiencies. In parallel with these experimental efforts we have pursued a techno-economic analysis as well as a life-cycle analysis of electroreduction to different products, including the separation steps needed before and after, to identify the most important areas that will need improvement to enhance economic feasibility and to ensure and maximize net negative greenhouse gas emissions.