CO2 mineral trapping: Hydrothermal experimental assessments on the thermodynamic stability of dawsonite at 4.3 Mpa pCO(2) and elevated temperatures

摘要

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 degrees 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 degrees 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 degrees 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 degrees 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 degrees C, dawsonite tends to dissolve. The effect of temperature on dawsonite indicates that the critical value at which dawsonite can remain stable is 120 degrees C. Dawsonite is stable at temperatures &120 degrees C; at temperatures 120 degrees C, the stability of dawsonite decreases and it converts to boehmite. (c) 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.