Mechanism of a reversible CO2 capture monitored by the layered perovskite Li2SrTa2O7

Abstract

We demonstrate for the first time, a new CO₂ capture ability monitored by a Ruddelsden–Popper compound. Under a humid CO₂ atmosphere, Li₂SrTa₂O₇ is transformed into LiHSrTa₂O₇ releasing lithium hydroxide which combined with the atmospheric CO₂ leads to Li₂CO₃. The presence of carbonate is confirmed by IR, thermal analysis coupled with mass spectroscopy and diffraction experiments (X-ray and neutron). The structural study of LiHSrTa₂O₇ performed with X-ray and neutron diffraction data showed that the structure differs from that of LiHSrTa₂O₇ obtained by ionic exchange from Li₂SrTa₂O₇ by the Li⁺/H⁺ repartition in the interlayer spacing. In the case of the LiHSrTa₂O₇ studied in this paper, the Li⁺ and H⁺ ions are ordered, while in the other form, each cation is unequally distributed on 2 sites. By heating, Li₂SrTa₂O₇ is recovered showing that the CO₂ capture is reversible and the cyclability of the CO₂ capture has been tested during six cycles.