Which technology is commonly used to remove NOx from exhaust and typically uses ammonia as a reducing agent?

Which technology is commonly used to remove NOx from exhaust and typically uses ammonia as a reducing agent?

• A. Selective catalytic reduction
• B. Wet scrubbing with lime
• C. Thermal oxidation
• D. Electrostatic precipitator

Answer: (A)

Selective catalytic reduction is a NOx control method that uses ammonia as the reducing agent. In this approach, ammonia is injected into the hot exhaust stream and, in the presence of a catalyst, reacts with nitrogen oxides to form nitrogen and water. This converts harmful NOx emissions into benign gases and is highly effective across a range of combustion sources, which is why it’s widely adopted. Other options operate on different pollutant types or mechanisms: wet scrubbing with lime neutralizes acid gases like sulfur oxides rather than reducing NOx with ammonia; thermal oxidation targets organic pollutants by burning them off at high temperatures; and an electrostatic precipitator removes particulate matter using an electric field rather than chemically converting NOx.

Selective catalytic reduction is a NOx control method that uses ammonia as the reducing agent. In this approach, ammonia is injected into the hot exhaust stream and, in the presence of a catalyst, reacts with nitrogen oxides to form nitrogen and water. This converts harmful NOx emissions into benign gases and is highly effective across a range of combustion sources, which is why it’s widely adopted.

Other options operate on different pollutant types or mechanisms: wet scrubbing with lime neutralizes acid gases like sulfur oxides rather than reducing NOx with ammonia; thermal oxidation targets organic pollutants by burning them off at high temperatures; and an electrostatic precipitator removes particulate matter using an electric field rather than chemically converting NOx.