Ammonia is a colorless gas and has a pungent smell. It consists of one nitrogen atom bonded to three hydrogen atoms. It occurs in nature from decaying organic matter and from smaller, man-made sources such as fertilizers, waste disposal, and industrial processes. Ammonia is highly toxic. It is irritating to the eyes, nose, throat, and respiratory tract and if inhaled at high concentrations, can cause death.
Ammonia emissions are regulated for nearly every application and are limited from all emissions control technologies. Ammonia is used as the reductant in the Selective Catalytic Reduction (SCR) of NOx. Johnson Matthey SCR systems utilize dosing control strategies to ensure the precise amount of ammonia (or urea, which decomposes to ammonia) is delivered to the honeycomb SCR catalyst or plate SCR catalyst minimizing ammonia emissions to the atmosphere. Ammonia Slip Catalysts (ASCs) are often coupled with SCR catalyst when both NOx conversion requirements and limits on ammonia emissions are exceptionally stringent.