Technologies for the nitrogen oxides reduction from flue gas: A review

The required energy of the global industry is mostly generated from fossil fuel sources, such as natural gas, gasoline, diesel, oil, and coal. Nitrogen oxides are one of the main air pollutants that are produced from the combustion of fossil fuels in stationary and mobile sources. Development of new technologies to decrease the NO_x emission from exhaust gases is essential due to the harmful effect of NO_x on the environment and human health. Compared with pre-combustion and combustion methods (with <50% NO_x removal efficiency), the post-combustion methods with higher efficiency (above 80%) have attracted more attention in NO_x elimination. This review describes the currently used technologies of NO_x abatement. Different available post-combustion methods of NO_x removal, including selective catalytic reduction (using different types of reducing reagents, including ammonia, hydrogen, hydrocarbons, and carbon monoxide), selective noncatalytic reduction, wet scrubbing, adsorption, electron beam, nonthermal plasma, and electrochemical reduction of NO_x, are discussed.