Post combustion methods for control of NOx emissions

This paper is a review of stack gas treatment methods for the control of NO_x emissions. Particular emphasis is placed on status of development and factors affecting the performance of the processes. Catalytic, noncatalytic, and scrubbing processes are compared on a uniform engineering basis. Most of the active process development work is taking place in Japan. The three leading stack gas treatment techniques for NO_x control are catalytic reduction with ammonia, noncatalytic reduction with ammonia, and direct scrubbing of NO with simultaneous absorption of SO₂. The wet processes are much less developed than the dry processes.