Metal Organic Framework for SO2 Capture

Abstract

Metal-organic framework (MOF) is a poriferous 3D framework, composed of organic ligands and central metal ions. The MOFs are often preferred for SO₂ capture due to their ligand function, large pore volume, simplicity of preparation as well as their relatively low cost of reactivation. In this review, the synthesis strategies achieving the formation of MOFs with higher porosity and strengthened reversibility were introduced. The synthesis processes include conventional heating, modulated synthesis, and post-synthetic modification (PSM). Conventional heating is categorized into two different methods, including electric heating and solvothermal synthesis. Electric heating usually involves using temperature change to produce target MOF whereas solvothermal synthesis is defined as reactions in enclosed containers under autogenic pressure past the boiling point of the solvent. Modulated synthesis and PSM also guarantee low by-products and great stability. The mechanisms of SO₂ adsorption were also discussed, which mainly focused on the physisorption that enables the utilizing resources to be efficiently used, as MOFs with physisorption are reusable. The adsorption site including strong hydrogen bonds and the uncoordinated atom with strong electronegativity also determines MOF’s ability. In addition, the influencing factors were interpreted to help demonstrate the mechanism of SO₂ adsorption. The SO₂ adsorption in the MOF is influenced by the pore structure, both the pore arrangement and the pore size, the guest binding to the SO₂ and the linkers to the SO₂.