Selectivity and direct visualization of carbon dioxide and sulfur dioxide in a decorated porous host

• Published in: Nature chemistry 2012-11, Vol.4 (11), p.887-894
• Main Authors: Yang, Sihai, Sun, Junliang, Ramirez-Cuesta, Anibal J., Callear, Samantha K., David, William I. F., Anderson, Daniel P., Newby, Ruth, Blake, Alexander J., Parker, Julia E., Tang, Chiu C., Schröder, Martin
• Format: Article
• Language: English
• Subjects: 639/301/299/1013; 639/638/263; 639/638/298/921; Analytical Chemistry; Biochemistry; Carbon dioxide; Chemistry; Chemistry/Food Science; Economics; Environmental impact; Gases; Hydrogen bonds; Inorganic Chemistry; Neutrons; Organic Chemistry; Physical Chemistry; Pores; Sulfur; Sulfur dioxide; Trapping; Visualization; X-ray diffraction
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/nchem.1457

Understanding the mechanism by which porous solids trap harmful gases such as CO 2 and SO 2 is essential for the design of new materials for their selective removal. Materials functionalized with amine groups dominate this field, largely because of their potential to form carbamates through H 2 N(δ − )···C(δ + )O 2 interactions, thereby trapping CO 2 covalently. However, the use of these materials is energy-intensive, with significant environmental impact. Here, we report a non-amine-containing porous solid (NOTT-300) in which hydroxyl groups within pores bind CO 2 and SO 2 selectively. In situ powder X-ray diffraction and inelastic neutron scattering studies, combined with modelling, reveal that hydroxyl groups bind CO 2 and SO 2 through the formation of O=C(S)=O(δ − )···H(δ + )–O hydrogen bonds, which are reinforced by weak supramolecular interactions with C–H atoms on the aromatic rings of the framework. This offers the potential for the application of new ‘easy-on/easy-off’ capture systems for CO 2 and SO 2 that carry fewer economic and environmental penalties. Porous solids are well suited to the capture of environmentally harmful gases, but further understanding of the solid–gas interactions involved is required. Combining dynamic and static characterization with modelling, researchers have now described how a metal–organic framework binds CO 2 and SO 2 selectively through hydroxyl groups — rather than amine ones as typically featured.