How does DEF work and what’s the point of it? Why can’t it just be added to the diesel when it’s processed?

Question

How does DEF work and what’s the point of it? Why can’t it just be added to the diesel when it’s processed?

In: Chemistry

Answer 1

It’s sprayed into the exhaust gas to break down some climate killer components (Nitrooxides) of it.

Too high temperatures in turn break it down (it’s Urea, the stuff thats also in your pee). Above 130°C it turns into other chemicals, so it must be used once the gas became cooler than that