Hi,
Learnt that my Diesel car is equipped with a DEF/AdBlue circuit to reduce the NOx emission.
That product is water with artificial urea.
To create artificial urea, industry needs to know the molecule definition.
So, chemists start from some organic samples but these samples are different, with various compositions, various oxidation levels…
How do chemists proceed to reduce the organic urea to a definition of a pure urea molecule ?
(I guess the process is more or less the same for every “reduction”)
Thanks !
In: Chemistry
It’s not actually super hard to make Urea. Urea is just CO(NH2)2
You can see from that all you really need is a source of carbon and oxygen, and a source of nitrogen and hydrogen. Luckily we have lots of the former; carbon dioxide, CO2, and its easy to make the latter; Ammonia, NH3. Both CO2 and nitrogen are found in air. I won’t go through making Ammonia; look up the Haber process. In short, you mix air with methane to put the hydrogens from the methane onto the nitrogen from the air.
So now you have ammonia and CO2. Pump both of those into the urea synthesis tank with appropriate heat and pressure and this reaction happens:
2NH3 + CO2 —> NH4CO2NH2
The new molecule is ammonium carbamate. It breaks down like this: NH4CO2NH2 <-> CO(NH2)2 + H2O
That is, it turns into pure urea and water. But it’s an equilibrium reaction and will balance itself out, so what you have to do is keep pumping or evaporating the water off to push the chemistry to keep it making urea. Then all you have to do is pump your urea into a storage tank and sell it off to the fuel company for them to mix it into whatever fuel additive they want.
You do not need any organic sources at all.
You can synthesize urea in large scale facilities from just carbon dioxide and ammonia (which you can make from hydrogen and nitrogen). You just need high pressures and temperatures and enough energy for the reactions.
So your urea plant, basically just needs air, water and natural gas as inlet and you get urea as output.
Dutch scientist Herman Boerhaave was the first to discovered urea in urine. The German scientist Friedrich Wöhler was the first to synthesize it from inorganic compounds.
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