Whelp, the chemistry of the catalytic reaction is real. How well it works in reality is a different question.
DEF is a 32.5% solution of urea, When it is injected into the hot exhaust gas stream, the water evaporates and the urea thermally decomposes to form ammonia and isocyanic acid.
The isocyanic acid hydrolyses from the water vapor to carbon dioxide and ammonia. From this point, ammonia, in the presence of oxygen and a catalyst, reduces nitrogen oxides.
I worked on developing the second generation of car catalytic converters when I worked at DuPont.
