Also known as: def.
DEF has various meanings in the Academic & science category. Discover the full forms, definitions, and usage contexts of DEF in Academic & science.
Selective catalytic reduction (SCR) systems utilize DEF to reduce NOx. DEF is made up of 32.5 percent urea and 67.5 percent de-ionized water. The ammonia in the urea mixes with engine exhaust gases in the SCR catalyst to convert NOx to nitrogen and water vapor.
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