Studies on the surface chemistry based on competitive adsorption of NO_x-SO₂ onto a KOH impregnated activated carbon in excess O₂

This study identifies surface chemistry characteristics based on competitive behavior in the simultaneous adsorption behavior of NO_x (NO rich) and SO₂ using KOH impregnated activated carbon (K-IAC) in excess O₂. The NO_x and SO₂ adsorption on K-IAC occurred mainly through the acid-base reaction. The high surface area with many pores of activated carbon acted as storage places of oxide crystal produced from NO_x and SO₂ adsorption. KOH, an impregnant, provided the selective adsorption sites to NO_x and SO₂, enabling simultaneous adsorption. However, larger amounts of SO₂, with higher adsorption affinity to K-IAC compared to NO_x were adsorbed in a NO_x/SO₂ coexistent atmosphere. Oxygen was chemisorbed to K-IAC, which enhanced the selective adsorptivity for NO. In binary-component adsorption of NO_x and SO₂ on K-IAC, oxide crystals such as KNO_x (x = 2,3) and K₂SO_x (x = 3,4) were dominantly formed through two different adsorption mechanisms by chemical reaction. Depending on the extent that oxide crystals blocked pores, compositions of oxide crystals were distributed differently according to depth.