Dehydrated Na₆[AlSiO₄]₆ sodalite as a promising SO₂ sorbent material: A first principles thermodynamics prediction

Abstract

The capture of sulfur dioxide (SO2) using dehydrated Na6[AlSiO4]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 SO2 adsorbates. Upon adsorption, the S atom of single SO2 molecule tends to align to the framework O2− and the two oxygen atoms are oriented to the framework Na+, through electrostatic interactions and with a minor charge transfer. Increasing the number of SO2 adsorbates, the Na6[AlSiO4]6 sodalite framework shrinks first and then expands. Statistical thermodynamics analysis suggests that the capture reaches its saturation limit of four SO2 molecules per Na6[AlSiO4]6 formula (~300 mg/g) at room temperature and a low SO2 partial pressure of 0.001 atm, indicating that dehydrated Na6[AlSiO4]6 can be an efficient SO2 sorbent even at its extremely low concentrations. Higher SO2 partial pressures lead to a higher capture capacity. A low baking temperature of 100‐150°C can efficiently release the adsorbed SO2 and hence restore the capture capacity of Na6[AlSiO4]6.

Materials for CO2, SOx, and NOx Emission Reduction

“…Such use of waste at the same time solves the problems of their disposal, while creating valuable raw materials. Sodalite was synthesized from such residues as a promising sorbent for SO 2 capture [57]. Statistical thermodynamic analysis shows that the capture reaches its saturation limit with four SO 2 molecules in the formula Na 6 [AlSiO 4 ] 6 at room temperature and low partial pressure of SO 2 , which indicates that dehydrated Na 6 [AlSiO 4 ] 6 can be an effective sorbent of SO 2 even at its extremely low concentrations.…”