CO2 mineral trapping: Hydrothermal experimental assessments on the thermodynamic stability of dawsonite at 4.3 Mpa pCO2 and elevated temperatures

Focused on the effects of temperature on the thermodynamic stability of dawsonite, a water†rock†CO2 interaction system was established. Water†rock experiments were conducted at different temperatures (80, 100, 120, 140, 160°C). Considering the evolution of the fluid in equilibrium with dawsonite and alteration of dawsonite by fluids, we discuss the critical temperature at which dawsonite can remain stable. The experimental data suggested that dissolution of dawsonite is common at 120°C and that the carboaluminate chains in the crystal break off, Na+ separates from the crystal lattice, and dawsonite begins to transform into boehmite. At 140°C, dawsonite dissolves dramatically, and the interior of the carboaluminate chains break off, CO32− separates from the crystal lattice, and dawsonite further transforms into boehmite. At 160°C, only Al†O and O†H bonds are retained in the dawsonite crystal and dawsonite completely converts to boehmite. The thermodynamic simulations determined that at temperature >120°C, dawsonite tends to dissolve. The effect of temperature on dawsonite indicates that the critical value at which dawsonite can remain stable is 120°C. Dawsonite is stable at temperatures