Calcium oxide - Wikipedia, the free encyclopedia
From what I find in this article, it looks like you can scrub CO2 from the air simply by heating and cooling Calcium Oxide.
So If I'm reading this correctly, you could start with CaCO3, and heat it up until it liberates it's CO2 (which you then collect), leaving just CaO. Then you can react CaO again with the air, and it grabs CO2 atoms to convert itself back into CaCO3. And we start the process over again.Calciumoxide is usually made by the thermal decomposition of materials such as limestone, that contain calcium carbonate (CaCO3; mineral calcite) in alime kiln. This is accomplished by heating the material to above 825 °C,[1] a process called calcination or lime-burning, to liberate a molecule of carbon dioxide (CO2); leaving quicklime. The quicklime is not stable and, when cooled, will spontaneously react with CO2 from the air until, after enough time, it is completely converted back to calcium carbonate.
I wonder how much energy is lost? Clearly some of the energy used to super heat the CaCO3 can be recovered by harnessing the heat from the CaO + CO2 reaction. But I don't know how much. I wonder if it would be possible to come close to a balance?
Chemical of the Week -- Lime
According to this article, the CaO + CO2 reaction actually goes faster if you make Ca(OH)2 out of the CaO first. So I've got part of the reaction here:
But I can't find a reaction with the energy released for the next stepCaO (s) + H2O (l)Ca(OH)2 (aq) (ΔHr = −63.7 kJ/mol of CaO)
Ca(OH)2(s) + CO2(g) CaCO3(s) + H2O(l)
So the main question: is there a good reason we couldn't use this to sequester lots and lots of CO2 from the air? Or maybe.... just maybe.... use that CO2 to make something like Methanol?