Acid gas such as SO2 and CO2 poses a great threat to human health and the environment, so there is an urgent need for efficient and commercial capture materials. In recent years, ionic liquids have been widely studied as potential sorbents for acid gas separation. However, their applications are still hindered by spatially crowded reactive sites, which greatly affects the absorption capability of each site and further reduces the total absorption capacity due to the "coverage effect". Here, we propose a more spacious tetra-branched framework as a new design for acid gas capture, which features isolated reactive sites with nearly uniform absorbing performance at each site. With the assistance of a hierarchical set of precision-increasing electronic structure calculations and structure screening algorithms automated by a series of Python scripts, an unprecedented absorbent-absorbate interaction configurational space has been searched. An unexpected but more stable absorbing (insertion) mode is identified and the novel mechanism is thoroughly analyzed. In addition, the cation effects on the interactions between tetra-branched anions and multiple acid gas molecules are also studied. Finally, tetra-branched sorbents with excellent absorbing performance are screened out.

Design and automatic screening of tetra-branched structures for multiple-site acid gas capture

2019 Fall National Meeting

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