Catalyst Offers New Hope for Capturing CO2 on the Cheap

[arendt]

Free summary:

Technology using chemicals that bind carbon dioxide already exists, but it's so expensive that using it on a large scale to suck CO2 out of the air could increase energy demand—and the cost of energy—by at least one-third. On page 313 of this week's issue of Science, however, researchers in the Netherlands report a new copper-based catalyst that can capture CO2, convert it to a different form, and then release it with a small fraction of the energy other techniques require. The new method targets the step that so far has proved to be the Achilles' heel of air capture: prying the trapped CO2 loose so the capture compound can be used again.

http://www.sciencemag.org/cgi/content/summary/327/5963/257-a

Snips from the subscription part:

X-ray crystallography showed that two pairs of the carbon complexes join together in a single unit to knit four CO2 molecules into two oxalates (see figure). ..the new catalyst’s ability to selectively bind CO2 and cause it to react is impressive.

Bouwman's group also worked out a way to regenerate the starting copper complex so that it could be used again. They simply added a lithium salt to their solution. The lithium swipes the oxalate from the copper complex, creating lithium oxalate. Then applying a very small voltage of –0.03 volts to the copper complex restores it to its original form.

This is great academic work, but nowhere near industrial scale. But, the intriguing result is that

The finding that a copper(I) system is oxidized by CO2 rather than O2 implies that the selective binding of CO2 to the copper(I) ions offers a low-energy pathway for the formation of the CO2+- radical anion.

Anyone who has played with CO2 knows that it is very hard to oxidize it. (Duh!)

[tabatha]

1. I think it was talking about CO2 as an oxidizer.

[arendt]

2. Blasted redox chemistry...

I know that creating the CO2+ anion is an energy-expensive bottleneck in the process.

It may be that un-ionized CO2 is a good oxidizer, but the article is about the CO2 radical ion. So I can't speak to your earlier statement (which I missed). Sorry.

I'm not a chemist, and I always get oxidized and reduced mixed up with oxidizing and reducing agents. I may have gotten this backwards.

I wish I could post the whole article for the chemists here.

[tabatha]

3. No problem.

Great article.

"Anyone who has played with CO2 knows that it is very hard to oxidize it."

That is true, too.