Dehydrated Na 6 [AlSiO 4 ] 6 sodalite as a promising SO 2 sorbent material: A first principles thermodynamics prediction

The capture of sulfur dioxide (SO 2 ) using dehydrated Na 6 [AlSiO 4 ] 6 sodalite was investigated using the first principles density functional theory calculations and thermodynamics analysis. The adsorption geometries, energetics, and electronic structures were predicted with the increasing number of SO 2 adsorbates. Upon adsorption, the S atom of single SO 2 molecule tends to align to the framework O 2− and the two oxygen atoms are oriented to the framework Na + , through electrostatic interactions and with a minor charge transfer. Increasing the number of SO 2 adsorbates, the Na 6 [AlSiO 4 ] 6 sodalite framework shrinks first and then expands. Statistical thermodynamics analysis suggests that the capture reaches its saturation limit of four SO 2 molecules per Na 6 [AlSiO 4 ] 6 formula (~300 mg/g) at room temperature and a low SO 2 partial pressure of 0.001 atm, indicating that dehydrated Na 6 [AlSiO 4 ] 6 can be an efficient SO 2 sorbent even at its extremely low concentrations. Higher SO 2 partial pressures lead to a higher capture capacity. A low baking temperature of 100‐150°C can efficiently release the adsorbed SO 2 and hence restore the capture capacity of Na 6 [AlSiO 4 ] 6 .