Mg₁₂O₁₂ and Be₁₂O₁₂ Nanocages as Sorbents and Sensors for H₂S and SO₂ Gases: A Theoretical Approach

Abstract

Theoretical calculations based on the Density Functional Theory (DFT) have been performed to investigate the interaction of H2S as well SO2 gaseous molecules at the surfaces of Be12O12 and Mg12O12 nano-cages. The results show that a Mg12O12 nano-cage is a better sorbent than a Be12O12 nano-cage for the considered gases. Moreover, the ability of SO2 gas to be adsorbed is higher than that of H2S gas. The HOMO–LUMO gap (Eg) of Be12O12 nano-cage is more sensitive to SO2 than H2S adsorption, while the Eg value of Mg12O12 nano-cage reveals higher sensitivity to H2S than SO2 adsorption. The molecular dynamic calculations show that the H2S molecule cannot be retained at the surface of a Be12O12 nano-cage within 300–700 K and cannot be retained on a Mg12O12 nano-cage at 700 K, while the SO2 molecule can be retained at the surfaces of Be12O12 and Mg12O12 nano-cages up to 700 K. Moreover, the thermodynamic calculations indicate that the reactions between H2S as well SO2 with Be12O12 and Mg12O12 nano-cages are exothermic. Our results suggest that we can use Be12O12 and Mg12O12 nano-cages as sorbents as well as sensors for H2S and SO2 gases.

Keywords

• adsorption of H₂S and SO₂
• BeO and MgO nano-cages
• density functional theory
• thermodynamics
• molecular dynamics