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Carbon Dioxide From the Air Converted Into Methanol (gizmag.com)
Zothecula writes: The danger posed by rising levels of atmospheric carbon dioxide has seen many schemes proposed to remove a proportion it from the air. Rather than simply capture this greenhouse gas and bury it in the ground, though, many experiments have managed to transform CO2 into useful things like carbon nanofibers or even fuels, such as diesel. Unfortunately, the over-arching problem with many of these conversions is the particularly high operating temperatures that require counterproductive amounts of energy to produce relatively low yields of fuel. Now researchers at the University of Southern California (USC) claim to have devised a way to take CO2 directly from the air and convert it into methanol using much lower temperatures and in a correspondingly simpler way.
They have to obey the laws of thermodynamics and conservation of energy? You don't say.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
From the article:
"To produce methanol from CO2 in the air, the researchers at USC's Dornsife College of Letters, Arts and Sciences first bubbled captured air through an aqueous solution of pentaethylenehexamine (PEHA), an ammonia-derived organic compound with multiple amino groups that – at raised temperatures – helps form chemical derivatives from alcohols. They then added a catalyst made from ruthenium (a member of the platinum group) to promote hydrogen attachment to the CO2 when the mixture was subject to high pressure.
The solution was then heated to around 125 to 165 C (257 to 359 F), and around 79 percent of the CO2 was converted into methanol. Though the resulting methanol was still mixed with water as it was produced, the researchers state that it can be easily separated using simple distillation processes. In addition, with the new method operating at such comparatively low temperatures, minimum decomposition of the catalyst meant that the researchers were able to repeat the process five times with minimal loss of the catalyst effectiveness. It also uses a homogeneous catalyst (that is, a soluble catalyst in solution with the chemicals it is reacting with) resulting in a simpler and faster "one-pot" process."
So they have to procure an amine in the pure form, mix it with purified water, heat it to 125 to 165 oC (a lot of energy, also under pressure), bubble the air through it (requiring at least the same pressure as the solution so there wouldn't be backflow) then recover the product using distillation (energy intensive). It's good chemistry and interesting catalysis, but I don't see how it will be cost-effective.
My guess is it would be cheaper to let a tree reduce the CO2, chop it down, and make the wood alcohol from that.
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Unless user Zothecula is actually Colin Jeffery, the author of the article, then it is disgracefully misleading to represent the content of the blurb as something that "Zothecula writes". Those words were instead lifted directly from the Jeffery's article, and no indication was made that this was done. Where I teach, anyone who shows this little regard for proper attribution gets a failing grade for plagiarism, and a second offense gets you expelled. It's depressing that a for-profit journalistic outlet could be so indifferent to plagiarism. If the article must be quoted in the blurb, then fucking quote it. You have a tag for that, and you also have the power to use quotation marks.
There are 44.6 moles per cubic meter of air. At 300 ppm, or 0.03% CO2, that would be 0.013 moles of CO2, at a 70% conversion rate you'd get 0.01 moles of methanol from 1 cubic meter of air. 1 kilogram of methanol (which isn't jet fuel, but never mind) is 31 moles of methanol. A 737 burns 3 kilograms of jet fuel per mile, let's say you want 6000 kilograms per trip. That means you'd need 3100 m^3 of air for one kilogram, or 18,600,000 m^3 of air. Assuming a residence time of a day for a facility to produce enough jet fuel for one flight, you'd need a facility with a total volume of 18,600,000 m^3. I'm not really sure it's cost effective to fly out a facility that as a minimum would be about 264 meters long, wide, and high. If the residence time were an hour, it would be about 100 meters on a side.
Another application is needed, this one won't cut it.
"Who are you?" "No one of consequence." "I must know." "Get used to disappointment."
Pure amines are expensive, and purifying water isn't cheap at the volumes this would need (see my other notes).
Note the process says it's aqueous, and therefore liquid. The temperature is 125-165 degrees, above the normal boiling point of water. Steam tables say 6 bars/atmospheres of pressure at 165 oC for pure water. 6 atmospheres isn't too bad for a pressure vessel, but you will need some engineering behind it.
Condensation requires energy, especially if you need a vacuum.
"Who are you?" "No one of consequence." "I must know." "Get used to disappointment."