(340d) Adsorption of CO2 on Rock Surfaces by Molecular Simulations

It is well knewn now that CO2 emission from the combustion of fossil fuels is a major reseason for the global warming. It is necessary to develop technologies that will allow us to utilize the fossil fuels while reducing the emissions of the green house gas. Existing commercial CO2 capture technology is very expensive and energy intensive. Improved technologies for CO2 capture are necessary to achieve low energy penalties. Preferential adsorption of CO2 on a porous adsorbent is one of key issues for the CO2 remove from gas stream. On the other hand, the CO2 capture from large emission sources is to produce a concentrated stream of CO2 that can be transported and sequestered underground or in deep oceans for different purposes, such as enhanced oil recovery (EOR). Understanding of CO2 adsorption on porous formations under geological conditions plays a key role in evaluating storability and safety in the practice of CO2 sequestration and/or EOR.

In this work, we studied adsorption of CO2, N2 and H2O on difference porous ‘rock' surfaces (quartz, calcite, magnesite, etc) by molecular simulations (grand canonical Monte Carlo and molecular dynamics). Adsorption isothermals and dynamic behavior of CO2 on the porous rock surfaces are in detail analyzed. Preliminary results show that the adsorption of CO2 on these porous rock surfaces decreases with temperature, but increases with pressure dramatically and that the adsorption of CO2 is much more than that of N2 or H2O on the porous rock surfaces at certain conditions. In addition, we compared with the CO2 adsorption on well-defined NaY zeolite. This study demonstrates the possibility of CO2 sequestration at difference geological conditions. It also presents a technical approach to evaluating the CO2 storability, and more importantly, a fundamental understanding for further studies relative CO2 sequestration, e.g., gas breakthrough pressure.