“…7,8 So far, many methods for controlling NO x contamination, including SCR (selective catalytic reduction) in the gas phase, absorption in the liquid phase and adsorption in the solid phase, have been developed and applied in industries. [9][10][11] However, the leakage of NH 3 causes air pollution in SCR methods and produces a large amount of wastewater and results in an increase in cost in absorption methods. Comparing the two above-mentioned methods, adsorption is better for the removal of NO x owing to its excellent characteristics of larger surface area, better selectivity, higher adsorption capacity and rate, better regeneration, and chemical stability.…”