Une nouvelle technologie de membrane a été mise au point qui permet d’éliminer plus efficacement le dioxyde de carbone des gaz mixtes, tels que les émissions des centrales électriques.
Des scientifiques ont mis au point une nouvelle technologie de membrane qui permet d’éliminer plus efficacement le dioxyde de carbone (CO 2).2) des gaz mixtes, tels que les émissions des centrales électriques.
“Pour démontrer la capacité de nos nouvelles membranes, nous avons étudié des mélanges de CO2 et d’azote, car le CO2/et le dioxyde d’azote sont particulièrement importants dans le contexte de la réduction des émissions de gaz à effet de serre des centrales électriques”, explique Rich Spontak, coauteur d’un article sur l’étude. “Et nous avons démontré que nous pouvons améliorer considérablement la sélectivité des membranes pour éliminer le CO2 tout en conservant un taux de CO2 perméabilité”.
“Nous avons également examiné des mélanges de CO2 et de méthane, ce qui est important pour l’industrie du gaz naturel”, explique M. Spontak, qui est professeur distingué de génie chimique et biomoléculaire et professeur de science des matériaux et de génie à North Carolina State University. “In addition, these CO2-filtering membranes can be used in any situation in which one needs to remove CO2 from mixed gases – whether it’s a biomedical application or scrubbing CO2 from the air in a submarine.”
Because membranes do not take up much physical space, they can be made in a wide variety of sizes, and they can be easily replaced, they are an attractive technology for removing CO2 from mixed gases. The other technology that is often used for CO2 removal is chemical absorption, which involves bubbling mixed gases through a column that contains a liquid amine – which removes CO2 from the gas. However, absorption technologies have a significantly larger footprint, and liquid amines tend to be toxic and corrosive.
These membrane filters function by allowing CO2 to pass through the membrane more quickly than the other constituents in the mixed gas. As a result, the gas exiting out the other side of the membrane has a higher proportion of CO2 than the gas entering the membrane. By capturing the gas passing out of the membrane, you capture more of the CO2 than you do of the other constituent gases.
A longstanding challenge for such membranes has been a trade-off between permeability and selectivity. The higher the permeability, the more quickly you can move gas through the membrane. But when permeability goes up, selectivity goes down – meaning that nitrogen, or other constituents, also pass through the membrane quickly – reducing the ratio of CO2 to other gases in the mixture. In other words, when selectivity goes down you capture relatively less CO2.
The team of researchers, from the U.S. and Norway, addressed this problem by growing chemically active polymer chains that are both hydrophilic and CO2-philic on the surface of existing membranes. This increases CO2 selectivity and causes relatively little reduction in permeability.
“In short, with little change in permeability, we’ve demonstrated that we can increase selectivity by as much as about 150 times,” says Marius Sandru, co-corresponding author of the paper and senior research scientist at SINTEF Industry, an independent research organization in Norway. “So we’re capturing much more CO2, relative to the other species in gas mixtures.”
Another challenge facing membrane CO2 filters is cost. The more effective previous membrane technologies were, the more expensive they tended to be.
“Because we wanted to create a technology that is commercially viable, our technology started with membranes that are already in widespread use,” says Spontak. “We then engineered the surface of these membranes to improve selectivity. And while this does increase the cost, we think the modified membranes will still be cost-effective.”
“Our next steps are to see the extent to which the techniques we developed here could be applied to other polymers to get comparable, or even superior, results; and to upscale the nanofabrication process,” Sandru says. “Honestly, even though the results here have been nothing short of exciting, we haven’t tried to optimize this modification process yet. Our paper reports proof-of-concept results.”
The researchers are also interested in exploring other applications, such as whether the new membrane technology could be used in biomedical ventilator devices or filtration devices in the aquaculture sector.
The researchers say they are open to working with industry partners in exploring any of these questions or opportunities to help mitigate global climate change and improve device function.
Reference: “An Integrated Materials Approach to Ultrapermeable and Ultraselective CO2 Polymer Membranes” by Marius Sandru, Eugenia M. Sandru, Wade F. Ingram, Jing Deng, Per M. Stenstad, Liyuan Deng and Richard J. Spontak, 31 March 2022, Science.
DOI: 10.1126/science.abj9351
The paper, “An Integrated Materials Approach to Ultrapermeable and Ultraselective CO2 Polymer Membranes,” is published in the journal Science. The paper was co-authored by Wade Ingram, a former Ph.D. student at NC State; Eugenia Sandru and Per Stenstad of SINTEF Industry; and Jing Deng and Liyuan Deng of the Norwegian University of Science & Technology.
The work was done with support from the Research Council of Norway; UEFSCDI Romania; the National Science Foundation, under grant number ECCS-2025064; and Kraton Corporation.
