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

We demonstrate for the first time, a new CO(2) capture ability monitored by a Ruddelsden-Popper compound. Under a humid CO(2) atmosphere, Li(2)SrTa(2)O(7) is transformed into LiHSrTa(2)O(7) releasing lithium hydroxide which combined with the atmospheric CO(2) leads to Li(2)CO(3). 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 LiHSrTa(2)O(7) performed with X-ray and neutron diffraction data showed that the structure differs from that of LiHSrTa(2)O(7) obtained by ionic exchange from Li(2)SrTa(2)O(7) by the Li(+)/H(+) repartition in the interlayer spacing. In the case of the LiHSrTa(2)O(7) 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, Li(2)SrTa(2)O(7) is recovered showing that the CO(2) capture is reversible and the cyclability of the CO(2) capture has been tested during six cycles.