2024-01-15 18:15:10
Scientists have devised a strategy to convert carbon dioxide (CO2) in the atmosphere into valuable carbon nanofibers. – ZHENHUA XIE/BROOKHAVEN NATIONAL LABORATORY
MADRID, 15 Ene. (EUROPA PRESS) –
Scientists in the US have developed a way to convert greenhouse gas CO2 into carbon nanofibers, material with many unique properties and great potential for long-lasting use.
Their strategy uses tandem electrochemical and thermochemical reactions that run at relatively low ambient temperatures and pressure. As the scientists – from Brookhaven National Laboratory and Columbia University – describe in the journal Nature Catalysis, this approach could successfully lock carbon into a useful solid form. to offset or even achieve negative carbon emissions.
“You can put carbon nanofibers in cement to strengthen it,” he said. it’s a statement Jingguang Chen, a professor of chemical engineering at Columbia with a joint appointment at Brookhaven Lab who led the research. “That would lock the carbon in the concrete for at least 50 years, potentially longer. By then, the world would need to shift to primarily using renewable, non-carbon-emitting energy sources.”
As an added benefit, the process also produces hydrogen gas (H2), a promising alternative fuel that, when used, generates zero emissions.
The idea of capturing CO2 or converting it into other materials to combat climate change is not new. But simply storing CO2 gas can cause leaks. And many CO2 conversions produce carbon-based chemicals or fuels that are used immediately, which releases CO2 back into the atmosphere.
“The novelty of this work is that we are trying to convert CO2 into something that has added value but in a solid and useful form,” Chen said.
These solid carbon materials, including carbon nanotubes and nanofibers with dimensions measuring billionths of a meter, have many attractive properties, including strength and thermal and electrical conductivity. But it’s not easy to extract carbon from carbon dioxide and get it to coalesce into these fine-scale structures. A direct heat-driven process requires temperatures in excess of 1,000 degrees Celsius.
“It’s very unrealistic for large-scale CO2 mitigation,” Chen said. “In contrast, we found a process that can occur at about 400 degrees Celsius, which is a much more practical and industrially achievable temperature.”
The trick was to divide the reaction into stages and use two different types of catalysts: materials that make it easier for molecules to come together and react.
“If the reaction is decoupled into several subreaction steps, the use of different types of energy input and catalysts can be considered. so that each part of the reaction works”, said Brookhaven Lab and Columbia research scientist Zhenhua Xie, lead author of the paper.
Scientists began by realizing that carbon monoxide (CO) is a much better starting material than CO2 for making carbon nanofibers (CNF). They then went back to find the most efficient way to generate CO from CO2.
For the second step, the scientists turned to a heat-activated thermocatalyst made of an iron-cobalt alloy. It operates at temperatures of around 400 degrees Celsius, significantly milder than a direct conversion from CO2 to CNF would require. They also found that adding some additional metal cobalt greatly improves the formation of carbon nanofibers.
“By combining electrocatalysis and thermocatalysis, we are using this process in tandem to achieve things that cannot be achieved with either process alone,” Chen said.
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