Adsorption experiments of supercritical CO2 by coals and comparisons of different description models

Abstract

Adsorption characteristic of supercritical CO2 on coal directly determines the CO2 geological storage capacity. Through volumetric method, this paper analyzed the manifestation effects of different models on the experimental data of various ranked coals and activated carbon. The results indicate that the variation rate of gaseous CO2 density reaches the peak around 8 MPa. Introduction of parameter k could improve the fitting quality and trap various experimental errors. The adsorption mechanism of coal samples from Tiefa and Wolonghu is micropore filling. As coal samples of Yaojie is collected from a CO2 -rich reservoir, the alteration effect by experimental CO2 adsorption is unobvious and its micropores develop quite well, thus the greatest absolute adsorption is higher than other samples. When the gas density increases gradually, the gap between excess adsorption and absolute adsorption widens, and the absolute adsorption determines the adsorption capacity of the coal samples. The fitting CO2 adsorbed phase density of the activated carbon by OK model is 1.004 g/cm3.

Keywords

• supercritical co2
• adsorption model
• micropore filling
• monolayer adsorption
• excess adsorption
• absolute adsorption