Improving the chances for fuel recovery and carbon sequestration
In a surprising turn, carbon dioxide goes from quickly bonding with to jumping off the surface of the layered clay kaolinite when the pressure increases beyond a critical value, according to scientists at Pacific Northwest National Laboratory (PNNL). When the CO2 pressure is sufficient to raise its density to 0.40 grams per cubic centimeter, CO2 becomes more mobile and leaves, or desorbs, from the kaolinite surface. Below this pressure, CO2 readily interacts with the clay, as noted in other studies. Here, the challenge was determining why the CO2's behavior was so peculiar when its density reached this level. By bringing together experiments and computational simulations, the team discovered that it was more energetically favorable for CO2 to move into the liquid-like supercritical phase as opposed to being bonded as a film on the clay surface as the pressure increases.