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Dr. Cao-Thang Dinh, left, and Dr. Md Golam Kibria demonstrate their new catalyst.

A new system using a thin copper-based catalyst and a new experimental strategy can convert greenhouse gas into a valuable renewable hydrocarbon.

Researchers from the University of Toronto have developed a new process to capture carbon dioxide (CO₂) produced by industrial processes and used renewable electricity, like solar power, and transform it into ethylene, a common industrial chemical that is a precursor to many commonly used plastics.

“When we performed the CO2 conversion to ethylene in very basic media, we found that our catalyst improved both the energy efficiency and selectivity of the conversion to the highest levels ever recorded,” post-doctoral fellow Cao-Thang Dinh, PhD, the first author on the paper, said in a statement.

The new system overcomes a significant barrier associated with carbon capture because it results in a commercially valuable product like ethylene. While technology exists to filter and extract CO2 from flue gases, the substance currently has little economic value that can offset the cost of capturing it.

The researchers then addressed the system’s stability, which has been a challenge with this type of copper-based catalyst. Theoretical modelling shows that basic conditions—high pH levels—are ideal for catalyzing CO2 to ethylene. However, under these conditions most catalysts with their supports, break down after less than 10 hours.

The new setup, which improved the efficiency and selectivity, is able to protect the support and catalyst from degrading because of the basic solution. It also enables it to last 15 times longer than previously catalysts.

“Over the last few decades, we've known that operating this reaction under basic conditions would help, but no one knew how to take advantage of that knowledge and transfer it into a practical system,” Dinh said. “We've shown how to overcome that challenge.”

The researchers were able to alter their experimental setup by depositing their catalyst on a porous support layer made of Teflon (polytetrafluoethylene) and sandwiched the catalyst with carbon on the other side.

The system is currently capable of performing the conversion on a laboratory scale and producing several grams of ethylene at a time. Eventually the researchers would like to scale the technology to the point where they are able to convert multiple tons of chemicals needed for commercial application.

"We made three simultaneous advances in this work: selectivity, energy-efficiency and stability," says Sargent. "As a group, we are strongly motivated to develop technologies that help us realize the global challenge of a carbon-neutral future."

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