Exploration of tetra-branched multiple-site SO2 capture materials

Abstract

We designed a series of tetra-branched anionic structures centered with Al for more efficient SO₂ capture. By using the home-made configuration search program coupled with electronic structure calculations, we have systematically explored the large reaction space consisting of these anions, cations, and SO₂ molecules. Unique insertion structures of the reaction complexes featuring a SO₂ molecule inserted into a branch were found to be prevalent and sometimes to be the ground states. Cations can either enhance or compress the anion–SO₂ interactions, highly depending on the anion, as they have multiple ways to interact with anions and SO₂ molecules. According to the calculated sequential SO₂ binding energies (with the cation effect included), [Al(Im)₄]⁻ is expected to be the best among the designed structures for reversible SO₂ capture. This approach can be easily extended to design and screen sorbents for other acidic gases.