Environment

Fluorinated membrane breaks a limit for capturing carbon dioxide

Fluorinated membrane breaks a ...
A new fluorine-based membrane could be better for capturing carbon dioxide emissions
A new fluorine-based membrane could be better for capturing carbon dioxide emissions
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A new fluorine-based membrane could be better for capturing carbon dioxide emissions
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A new fluorine-based membrane could be better for capturing carbon dioxide emissions
An artist's impression of a fluorine-based membrane that selectively filters out carbon dioxide
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An artist's impression of a fluorine-based membrane that selectively filters out carbon dioxide

Carbon dioxide is an all too common waste product of industry, belched into the air in huge amounts from smokestacks. Now, researchers have developed a new type of fluorinated membrane that can selectively filter CO2 out of flue gas at the point of release.

Carbon capture is a promising avenue of research to help slow the march of climate change, preventing greenhouse gases from being released in the first place. To this end, scientists are exploring many different technologies, including clay, bubble-like membranes, ionic liquids, metal-organic frameworks, and porous powders.

The new study, by researchers at Oak Ridge National Laboratory and the University of Tennessee, builds on one of the simplest forms of carbon capture: polymer membranes. These can be stretched across a facility’s chimney where they selectively filter carbon dioxide out of flue gas, while allowing gases like oxygen and nitrogen to escape into the atmosphere.

The secret ingredient of the team’s new membrane is fluorine. This element bonds particularly strongly to carbon, making it an attractive option for carbon capture. The researchers started with a fluorine-based polymer, then heated it to carbonize it. This gives the material a porous structure while maintaining the fluorinated groups, which boosts how much it selects for CO2.

An artist's impression of a fluorine-based membrane that selectively filters out carbon dioxide
An artist's impression of a fluorine-based membrane that selectively filters out carbon dioxide

“The approach resulted in a carbon dioxide-philic material with high surface area and ultra-micropores that is stable in high-temperature operating conditions,” says Zhenzhen Yang, first author of the study. “All of these factors make it a promising candidate for carbon-capture and separation membranes.”

Normally, membranes like this have a trade-off between selectivity for certain gases, and permeability – as one goes up, the other goes down. But the team says that the fluorine-based membrane balances the two properties well, breaking what’s known as the Robeson upper limit. Few materials have achieved this, the team says.

Better yet, fluorine and the other starting materials are abundant and inexpensive, and the process to make them is simple, which will help in scaling up.

In future work, the team plans to further investigate the mechanism for fluorine’s CO2 selectivity, and try to improve the recipe further.

The research was published in the journal Chem.

Source: Oak Ridge National Laboratory

7 comments
entitledparasite
It is reassuring to see the effort being made to capture CO2. Given that we have built a CO2 greenhouse around the earth, dismantling the greenhouse ASAP should be first priority for as long as it exists it will continue to warm the earth even if our emissions are completely eliminated.
Douglas Bennett Rogers
CO2 has a molecular weight of 44. Carbon has an atomic weight of 12. The weight of recovered product is 44/12 times the weight of the coal burned! You would need a train 44/12 times as big as the one delivering coal moving past the collection point! As to greenhouse effect, water vapor accounts for 95% of it! Everyone in the infra red world knows this! Not that the 1% that comes from added CO2 isn't worth dealing with. Because of the above, sequestration generally makes coal and gas cost ineffective. Some day, when we need the carbon for sky hooks, we might use nuclear fusion to extract it from the air.
DaveWesely
The whole CO2 extraction isn't bad. But think about it. Once you have collected the CO2, what do you do with it? Sell it! Dry ice, carbonated drinks, etc. But all of those uses release it into the atmosphere. It can be used for crude oil extraction though. Yeesh.
This whole issue reminds me of a 60 minutes episode 25 years ago. A company developed a pollution detection device and offered to sell it for $100k each to the government. Congress was on board. A scientist caught wind of it and developed the same device for under $10 with a coffee can. The whole project was dropped.
Congress wasn't interested in a solution, they were only interested in the campaign kickbacks, oops, contributions.
These CO2 capture schemes are pushed and developed for fossil fuel industries. They make good press and give people the impression global warming will be solved. But it won't work that way.
We need to take carbon gas from the air and turn it into carbon solids. The only way to do that cost effectively is through pyrolysis of organic material. But that only benefits farmers. So that solution is dropped.
Worzel
When all the CO2 is extracted from the air, then the planet will become totally free of carbon based life forms, (almost all on the planet), and ready for any passing non carbon alien to colonise.
Anyone who believes that CO2 causes climate change, is, well, misinformed, and gullible. It has not done so during the last 600 million years. It is a vast political scam.
As for warming, the planet is presently, and throughout this present glacial period, the coldest it has been since the Permian extinction, 270 million years ago, and it will get colder, a lot colder.
The planet orbits the sun, but the solar system orbits the centre of the galaxy, independently from the rotation of the galaxy, with a period of around 600 million years. 600 million years ago, the planet exited an ice age that is called the ''Snowball Earth'' event, when the planet was totally covered in ice, and all life, except bacteria and similar organisms was extinguished. The ice ages occur at approximately 150 million year intervals and last for tens of millions of years. They are caused by the solar system passing through the arms of the galaxy, and interstellar dust attenuating the suns radiation reaching the planet. The present ice age, started more than 40 million years ago, and could well be a repeat of the Snowball Earth event.
So, a warming planet is of no consequence, the biggest danger to all life is a cooling planet, like now.
The deerhunter
I was sceptical when I read the brief article and after reading the other comments, my scepticism appears to be well-founded. In other words, it may work but probably is of no practical use
KeithDPatch
As a multi-degreed MIT chemical engineer fluent in many aspects of the Energy Transition (in Germany), I applaud their efforts.

However, a membrane-based carbon capture approach is basically doomed to fail, given the particulate matter that accompanies fossil-fueled products of combustion (PM2.5, black soot, sulfurous particles, etc.)

A further, cost-related problem with this fluorinated membrane-based approach can be evidenced by examinining the PEM hydrogen fuel cell arena. Today these PEM fuel cell devices usually use Nafion, a fluorinated polymer membrane, which is very expensive. Many teams are trying to replace Nafion with a lower-cost, but well-performing non-fluorinated membranes. To-date, nothing has broken through.

At least they got a publication in a good journal...
ljaques
Go, Polymer! Sure, capture some CO2, but go after real pollutants, too, sometimes, researchers. (I've always loved the pictures of steam release to suggest pollution from stacks.) I want my Mr. Fusion so I can fly my huge Tundra pickup around. Hurry on that tech, too, researchers.