Theoretical study on NOx adsorption properties over the α-MnO2(110) surface

Abstract

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.