METHOD FOR REMOVING NITROGEN OXIDE

PROBLEM TO BE SOLVED: To provide a method for removing nitrogen oxides without the presence of a catalyst that can remove nitrogen oxides in a highly efficient manner and significantly reduce the amount of unreacted ammonia.SOLUTION: The method for removing nitrogen oxides includes: bringing exhaust gas containing oxygen and at least one nitrogen oxide selected from the group consisting of nitrogen monoxide and nitrogen dioxide into contact with ammonia without the presence of a catalyst, for at least 0.5 seconds under a temperature of ≥900°C; and decomposing the nitrogen oxide. The exhaust gas is brought into contact with the ammonia preferably under a temperature of 900-1,200°C, and the ammonia is supplied preferably 1.0-3.0 times as much as the nitrogen oxides in terms of mol.