Carbon dioxide adsorption isotherm study on various cap rocks in a batch reactor for CO2 sequestration processes

The purpose of this article is to present the effects of CO2 adsorption on sealing rocks in the context of carbon dioxide sequestration. Various samples (clay, sandstone and evaporates) have been experimentally reacted in a low-salinity water with supercritical CO2 in situ reservoir conditions (P = 80 bars and T = 80 °C). Adsorbents were characterized thoroughly via X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption. Adsorption isotherms were measured at T = 298 K, 353 K. Experimental data of CO2 adsorption isotherms were modeled using Langmuir models. Based on the correlation coefficient, the isotherm model is well suited to the experimental data of CO2 adsorption isotherms. Limiting heat of adsorption at zero and isosteric heat as a function of the surface coverage were evaluated using Clausius-Clapeyron equations. These thermodynamic properties indicate that the uptaken CO2 occurred mainly by physi-adsorption phenomenon. The adsorption isotherms data and the thermodynamic parameters estimated in the present study are useful for the designing of the adsorption based gas storage systems.