Environment

Liquid metal catalyst quickly converts carbon dioxide into solid carbon

Liquid metal catalyst quickly ...
Karma Zuraiqi, lead author of the study, holds a vial of the liquid metal catalyst
Karma Zuraiqi, lead author of the study, holds a vial of the liquid metal catalyst
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Karma Zuraiqi, lead author of the study, holds a vial of the liquid metal catalyst
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Karma Zuraiqi, lead author of the study, holds a vial of the liquid metal catalyst

Researchers at RMIT have developed a new method for quickly converting carbon dioxide into solid carbon, which can be stored indefinitely or turned into useful materials. The technology works by bubbling CO2 up through a tube of liquid metal, and it’s designed to be easy to integrate into the source of emissions.

Reducing carbon dioxide emissions is crucial for the future of the planet, and a major part of that may involve finding ways to capture it at the point of emission. Current methods in development include filtering the gas through absorbent materials like magnetic sponges, bubble-like membranes, zeolite foam, or materials made of clay or coffee grounds.

The RMIT team’s new system uses liquid metal, specifically an alloy called Eutectic Gallium-Indium (EGaIn), which is heated to between 100 and 120 °C (212 and 248 °F). Then, carbon dioxide is injected into the mix, and as the bubbles rise, the CO2 molecules split into flakes of solid carbon. These float to the top, making it easy to collect the material.

The team says that the design of the system should be relatively easy to scale up and implement at the point of emission. The reaction occurs quickly and efficiently, and the heat required is also relatively low, and could be supplied by renewable sources. All of these are improvements on the team’s earlier work, which required more hands-on steps.

But perhaps the biggest advantage is that the end result is solid carbon. Many other forms of carbon capture keep it as gaseous CO2, which can be trickier to store and transport, and prone to leak back into the air. Even attempts to stash it underground, where it can turn back into solid rock within a few years, isn’t foolproof, with large proportions remaining in gas form, ready to belch back out if the seal is broken.

Solid carbon, on the other hand, is stable, and could be stored more or less indefinitely without risk of leakage. The team says this could be buried again, or, more promisingly, used for other industrial applications, such as making concrete.

The next steps for the team are to scale up the system to a modular prototype that’s about the size of a shipping container.

The research was published in the journal Energy & Environmental Science, and the team demonstrates the technique in the video below.

Liquid metal instantly converts CO2 to solid carbon | RMIT University

Source: RMIT

21 comments
21 comments
Peter Flynn
Think it’s important to advise if the gas can be a mix or has to be pure co2. Most capture scenarios there are other things present. Separating the co2 is half the trick.
Static
Teach a human to fish.... save the earth... na we are to stupid for that.
ClauS
Just one question, what is that solid carbon? As far as I know solid carbon is graphite or even coal. Then this capture seems to be a reversal of the combustion process, inevitably with lower efficiency. Probably not useful at a power plant but maybe at some furnaces.
Rumata
We can use this technology to produce carbon flakes from the exhaust gases of our coal-fired power station.
And if we burn those carbon flakes in our coal-fired power station, then we can have a zero-emission perpetum mobile :-DDD
Mattiede
Didn't read the original article, but sounds like an economical nonsense to me. You burn C and O2 to get energy and CO2, then convert CO2 back to C and O2(?) - can't possibly be energy efficient following the laws of thermodynamics. So you need more energy to separate CO2 than You get burning C. Better to use the energ from renewables directly. Interesting discovery though from a chemical point of view.
Andrew O'Donnell
If all this is true and turns out to be easy to scale cost effectively, it could be an essential part of the solution to climate change. What is the downside?

Also, several other comments seem to show misunderstanding of the article. The process doesn't make coal, it makes solid carbon. There's a big difference. Coal has a lot of carbon in it, but carbon alone is not combustible.
pmshah
So how is the oxygen collected ? Or is it just released in the atmosphere? I suppose this could be big boon for submarines if it can be sufficiently scaled up. I guess the next challenge would be to find/manufacture sufficient quantities of Eutectic Gallium-Indium (EGaIn)
michael_dowling
Gallium and Indium are rare earth metals,and expensive.
John Schubert
My last chemistry class was 54 years ago, but I remember this much: Making any chemical change to carbon dioxide demands a large input of energy.
This article coyly avoids saying, "How much energy."
So, let us suppose that you burn a fuel -- coal, oil, wood, gas, whatever . . . and you produce X amount of energy and Y amount of carbon dioxide.
What are the chances that the energy required to make that carbon dioxide into a lump of solid carbon and a bunch of oxygen is less than X?
I say the chances are zero. But the chemistry experts are welcome to refute me.
jonathan goldstein
What happens to the oxygen in the carbon dioxide when the carbon splits off ? Does it just bubble off as oxygen or does it form oxides with the indium gallium if so very problematic as the oxidized very costly liquid metal will need to be processed.
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