5:15 PM - 6:45 PM
[SMP23-P03] The effect of dissolved carbonate species on carbonation reaction of forsterite
Keywords:Forsterite, Magnesite, Carbonation, GCS
Recently, geological carbon sequestration (GCS), one of the carbon dioxide capture and storage (CCS) techniques, has attracted attention from the perspective of carbon neutrality. GCS is a method in which CO2 injected into a rock body reacts with minerals in rock, and is sequestered as chemically stable carbonate minerals through a carbonation reaction. Forsterite (Mg2SiO4) is ubiquitous in basic rocks such as peridotite and basalt and also the most weatherable rock-forming minerals. In addition, forsterite readily reacts with the CO2-rich hydrothermal fluids to form lizardite [Mg3Si2O5(OH)4], talc [Mg3Si4O10(OH)2], and magnesite (MgCO3). Magnesite is chemically stable even on geological time scales and is one of the most useful minerals as a CO2 reservoir.
Due to its high reactivity and CO2 absorption potential, forsterite is recognized as the most promising target for the GCS. Many studies have been therefore conducted for the carbonation mechanism of forsterite. In the hydrothermal reaction, the optimal conditions to promote the carbonation of forsterite have been reported to be 1 M NaCl + 0.64 M NaHCO3 at T ≈ 180 °C and PCO2 ≈ 135 bar (Bearat et al., 2006). The effect of dissolved carbonate species on the mineral carbonation has been however unclear and still discussed. In this study, we performed hydrothermal experiments of the mineral carbonation between forsterite and dissolved carbon dioxide (CO2aq). The synchrotron X-ray diffraction (XRD) study was performed at KEK-PF BL8B using a large two-dimensional imaging plate detector to analyze the reaction products.
After the hydrothermal reaction for 24 h, two products were formed depending on the reaction temperature. At 140 °C, lizardite was obtained, but with increasing temperature magnesite was formed with lizardite. At 200 °C for 5 days, only magnesite was formed, but no significant changes were observed with reaction time. The formation of magnesite was accelerated with the addition of NaCl and KCl into the hydrothermal system. The results suggest that the carbonation reaction of forsterite varies depending not only on temperature and the presence of alkali metal ions but also dissolved carbonate species.
Due to its high reactivity and CO2 absorption potential, forsterite is recognized as the most promising target for the GCS. Many studies have been therefore conducted for the carbonation mechanism of forsterite. In the hydrothermal reaction, the optimal conditions to promote the carbonation of forsterite have been reported to be 1 M NaCl + 0.64 M NaHCO3 at T ≈ 180 °C and PCO2 ≈ 135 bar (Bearat et al., 2006). The effect of dissolved carbonate species on the mineral carbonation has been however unclear and still discussed. In this study, we performed hydrothermal experiments of the mineral carbonation between forsterite and dissolved carbon dioxide (CO2aq). The synchrotron X-ray diffraction (XRD) study was performed at KEK-PF BL8B using a large two-dimensional imaging plate detector to analyze the reaction products.
After the hydrothermal reaction for 24 h, two products were formed depending on the reaction temperature. At 140 °C, lizardite was obtained, but with increasing temperature magnesite was formed with lizardite. At 200 °C for 5 days, only magnesite was formed, but no significant changes were observed with reaction time. The formation of magnesite was accelerated with the addition of NaCl and KCl into the hydrothermal system. The results suggest that the carbonation reaction of forsterite varies depending not only on temperature and the presence of alkali metal ions but also dissolved carbonate species.