Sciencemadness Discussion Board

Diesel Exhaust Fluid - Urea - catalyzed ammonia to N2?

RogueRose - 12-4-2019 at 13:38

I'm pretty confused as to what is happening in this DEF system and it seems the opposite of experiments we have done to convert ammonia to NO2..

The DEF/urea solution is injected at the exhaust manifold and it decomposes to Ammonia and isocyanic acid - the ICA then hydrolyzes to ammonia and CO2. Then the gases pass through the Catalytic converter, supposedly turning it into N2.

Now the experiments that some have done using Pl/Pd is converting NH3 to NO2. How can the same process do both?

https://en.wikipedia.org/wiki/Diesel_exhaust_fluid

[Edited on 4-12-2019 by RogueRose]

[Edited on 4-13-2019 by RogueRose]

rockyit98 - 12-4-2019 at 18:05

Diesel and Urea
Periodic Video
The Professor discusses some of the chemistry behind the recent controversy involving Volkswagen cars.
https://www.youtube.com/watch?v=WkpoL-aQbdI

wg48temp9 - 12-4-2019 at 23:28

Quote: Originally posted by RogueRose  
I'm pretty confused as to what is happening in this DEF system and it seems the opposite of experiments we have done to convert ammonia to NO2..

The DEF/urea solution is injected at the exhaust manifold and it decomposes to Ammonia and isocyanic acid - the ICA then hydrolyzes to ammonia and CO2. Then the gases pass through the Catalytic converter, supposedly turning it into N2.

Now the experiments that some have done using Pl/Pd is converting NH3 to NO2. How can the same process do both?


Catalysts only change the rate of the reaction by reducing the energy barrier to the reaction they are therefore inherently reversible.

For example you can use sulphuric acid to catalyze the creation an ester and you can use sulphuric acid to hydrolyse an ester back into the original reactants.