SCR denitration technology SCR (Selective Catalytic Reduction) is the Selective Catalytic Reduction technology, rapid development in recent years, has been widely used in Western Europe and Japan, currently ammonia Catalytic Reduction method is used most frequently. It has no by-products, do not form secondary pollution, device has simple structure, and high removal efficiency (up to more than 90%), reliable operation, easy to maintenance etc, and is sold out at present is the most mature technology.

Selectivity refers to the catalyst and under the condition of oxygen exists, NH₃ priority and reduction of NOx removal reaction, generate nitrogen and water, and the oxidation reaction with oxygen in flue gas, its main equation is:

4NO+4NH₃+O2→4N₂+6H₂O（1）

2NO₂+4NH₃ +O2→ 3N₂+6H₂O（2）

SCR denitration technology, the principle of SCR denitration technology is under the action of catalyst and reducing agent (ammonia) react with nitrogen oxide in flue gas to generate harmless nitrogen and water, so as to remove the NOx in flue gas. Selective means reducing agent NH₃ and NOx in flue gas reduction reaction occurs, and does not react with the oxygen in flue gas.