From lemons to lemonade: Reaction uses carbon dioxide to make carbon-based semiconductor

phys.org ^ | 5/21/12 | Marcia Goodrich

[LibWhacker]

(Phys.org) -- A materials scientist at Michigan Technological University has discovered a chemical reaction that not only eats up the greenhouse gas carbon dioxide, it also creates something useful. And, by the way, it releases energy.

Making carbon-based products from CO2 is nothing new, but carbon dioxide molecules are so stable that those reactions usually take up a lot of energy. If that energy were to come from fossil fuels, over time the chemical reactions would ultimately result in more carbon dioxide entering the atmosphere—defeating the purpose of a process that could otherwise help mitigate climate change.

Professor Yun Hang Hu’s research team developed a heat-releasing reaction between carbon dioxide and Li3N that forms two chemicals: amorphous carbon nitride (C3N4), a semiconductor; and lithium cyanamide (Li2CN2), a precursor to fertilizers.

“The reaction converts CO2 to a solid material,” said Hu. “That would be good even if it weren’t useful, but it is.”

And how much energy does it release? Plenty. Hu’s team added carbon dioxide to less than a gram of Li3N at 330 degrees Celsius, and the surrounding temperature jumped almost immediately to about 1,000 degrees Celsius, or 1,832 degrees Fahrenheit, about the temperature of lava exiting a volcano.

Hu’s work is funded by the National Science Foundation and detailed in the article “Fast and Exothermic Reaction of CO2 and Li3N into C–N-Containing Solid Materials,” authored by Hu and graduate student Yan Huo and published in the Journal of Physical Chemistry.

[PapaBear3625]

By the way, Li3N will be very water sensitive, so much so that I expect it will react spontaneously with moisture in the atmosphere, which will further complicate any real use of this system.

A bigger complication: you get Li3N by exposing Li to nitrogen. Refining lithium, however, consumes 35 kWh/kg. In comparison, burning one kg of coal produces just 2 kWh of heat energy (and much less than that in actual electrical output)

[MrB]

I reject the premise of the title that CO2 is “lemons”.

[Suz in AZ]

Very cool. But I still don’t get why people want to suffocate the plants.

[FreeAtlanta]

Another fertilizer bomb...

This tech does seem pretty cool. It it is as good as it sounds, Al Gore and the other environmental pimps won't be happy because they really don't want solutions.

[monocle]

In my gut I suspect that the formation of lithium nitride requires a lot of energy, particularly if the starting material is elemental lithium. Production of elemental lithium is a highly energy intensive process.

[TXnMA]

17.5 X Coal energy cost -- forget it!

Bingo! The answer as to why this will remain a laboratory curiosity -- at least as far as disposal of CO₂ is concerned.

IF somone develops a semiconductor process/product based on the reaction product, a few Kg of CO₂ might be sequestered by it. Qtherwise, it is a mere curiosity...

Of course, let me be the first to point out that there is ZERO need to "sequester" atmospheric CO₂ in the first place...