Photoinduced Carbon Dioxide Release via a Metastable Photoacid in a Nonaqueous Environment
Daniel E. Cotton, Thien Khuu, Kana Takematsu, Berk Delibas, Jahan M. Dawlaty
Abstract
Capturing carbon dioxide (CO 2 ) from the atmosphere is a scientific and technological challenge. CO 2 can be captured by forming carbamate bonds with amines, most notably monoethanolamine (MEA). Regenerating MEA by releasing captured CO 2 requires that the carbamate solution be heated. Recently, photoacids were used to induce a pH change to release CO 2 from aqueous carbonate solutions. We report a merocyanine photoacid that releases CO 2 from nonaqueous carbamate solutions of MEA, which has a CO 2 loading capacity that is higher than that of water. On the basis of the absorption spectra of the photoacid in the presence of acids and CO 2, we show that the photoacid cycle and the CO 2 capture of MEA are two separate equilibria coupled to each other via protons. We demonstrate that irradiating the sample with 405 nm light induces the release of CO 2, which we detect using an in-line mass spectrometer. This work highlights an alternative path for optimizing a photoinduced CO 2 capture and release system.