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Copper-powered carbon sequestration

We’ve heard about carbon sequestration, deep beneath the Earth, but now here’s another way of dealing with the CO₂ problem - with copper.

Part of the reason that CO₂ is a problem is that it’s quite tricky to extract it from the air as it’s quite a stable molecule, at least compared with oxygen. And so most of the time gaseous oxygen will bond to a metal, for example, before carbon dioxide does.

But this new copper complex, reported in the journal Science this week, can ignore boring old O₂ and go straight for CO₂.

A team of researchers, led by Elisabeth Bouwman at the Leiden Institute of Chemistry, say that typically, the problem with oxygen is that it will gain an electron more readily than CO₂. But this copper complex will happily donate electrons to carbon dioxide instead.

So, to extract CO₂ from the air, they put this copper complex into solution. Atmospheric CO₂ to which it’s exposed is then absorbed. Next, to remove the captured carbon, they just added a lithium salt solution, apply a low voltage - 0.03V - across it, and the carbon precipitates as an organic compound.

As a bonus, this by-product can be converted into useful compounds which can be used in cleaning products and things like wood preservation.

But what’s really useful is that the copper complex can be cleaned at the end of the reaction and re-used. The researchers report that they managed to do this six times in seven hours.

Also, compared with other methods of sequestration, it’s actually quite cheap although there is a possibility that accessible copper ores might run dry not too far into the future!

17th Jan 2010

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