Theoretical study on NO x adsorption properties over the α-MnO2(110) surface.

Herein, α-MnO2 was studied as an adsorbent for the removal of NO x (NO, NO2) derived from flue gas. First-principles calculations based on the density functional theory (DFT) were performed to investigate the NO x adsorption properties over the α-MnO2(110) surface. NO strongly adsorbed over the α-MnO2(110) surface via chemisorption spontaneously under 550 K. The NO2 molecules adsorbed over the surface via chemisorption and physisorption when the terminal N- and O atoms approached the surface, respectively. The joint adsorption of NO x was more stable than the isolated adsorption system. Furthermore, the net charge was transferred from the molecule to the surface. The surface and temperature affected the entropy, enthalpy, NO adsorption and NO2 desorption in the temperature range of 300-550 K. The equilibrium constants decreased with an increase in temperature, which reduced the conversion rate.