A new University of Illinois at Urbana-Champaign study introduced an electrochemical reaction, enhanced by polymers, to improve CO2-to-ethylene conversion efficiency over previous attempts. For years, researchers have worked to repurpose excess atmospheric carbon dioxide into new chemicals, fuels and other products traditionally made from hydrocarbons harvested from fossil fuels. The recent push to mitigate the climactic effects of greenhouse gases in the atmosphere has chemists at work to find the most efficient means possible.

The results of the study led by University of Illinois Urbana-Champaign chemistry professor Andrew Gewirth and graduate student Xinyi (Stephanie) Chen have been published in the journal Natural Catalysis.

The study noted that allowing CO2 gas to flow through a reaction chamber fitted with copper electrodes and an electrolyte solution is today’s most common method researchers use to convert CO2 to useful carbon-containing chemicals.

Professor Gewirth said, “Copper metal is highly selective toward the type of carbon that forms ethylene. Different electrode materials will produce different chemicals like carbon monoxide instead of ethylene, or a mix of other carbon chemicals. What we have done in this study is to design a new kind of copper electrode that produces almost entirely ethylene.”

CO2 to polymer entrained electrodes to ethylene. Image Credit: University of Illinois at Urbana-Champaign. Click image for the largest view.

The study noted that previous studies have used other metals and molecular coatings on the electrode to help direct the CO2-reduction reactions. However, these coatings are not stable, often break down during the reaction process and fall away from the electrodes

Stephanie Chen explained the team’s work, “What we did differently in this study was to combine the copper ions and polymers into a solution, then apply that solution to an electrode, entraining the polymer into the copper.”

In the lab, the team found that the new polymer-entrained electrodes were less likely to break down and produced more stable chemical intermediates, resulting in more efficient ethylene production. “We were able to convert CO2 to ethylene at a rate of up to 87%, depending on the electrolyte used,” Chen said. “That is up from previous reports of conversion rates of about 80% using other types of electrodes.”

Gewirth added, “With the development of economic sources of electricity, combined with the increased interest in CO2-reduction technology, we see great potential for commercialization of this process.”

This research will raise a lot of hope for recycling carbon dioxide. And that hope will be justified as this is significant progress. As catalyzing CO2 goes, any progress is encouraging and when you get a very important chemical product like ethylene at 87% you’ve made quite a marker. Getting to 87% is nearly a complete recycling, and the results in the study about the remaining 13% isn’t going to send process engineers into a hopeless blue funk.

The problem is the abundance and price of ethylene. We’re already using far more of it than most folks realize. Its good this technology is close to ready when prices swing again.


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