Adsorption and Desorption of Carbon Dioxide onto and from Activated Carbon at High Pressures

Abstract

Adsorption of carbon dioxide near its critical point on DeGussa IV activated carbon is investigated in this study. A volumetric method was used to measure the adsorption/desorption isotherms at 284, 300, 305, 310, and 314 K over a large pressure range. At subcritical temperatures, adsorption isotherms display a discontinuity at the vapor pressure of carbon dioxide, and desorption hysteresis is observed. However, there is no desorption hysteresis if adsorption is terminated before vapor−liquid transition occurs. At supercritical temperatures, adsorption isotherms display a plateau, and the excess decreases beyond the critical pressure. No hysteresis occurs during the desorption process. The adsorption isotherms can be represented very well by the simplified local density model.

A New Method to Calculate the Absolute Amount of Supercritical Methane Adsorption on Organic-Rich Shale

“…The potential of fluid-solid interaction, fs (z) can be calculated by the following equation (Chen et al 1997;Chareonsuppanimit et al 2012): (10) Where n is the number of adsorbent plane atoms per unit area, ε fs is the gas-solid interaction energy parameters, σ ss is the absorbent interplanar distance, σ fs is the distance interaction of adsorbate molecule and adsorbent molecule, in general σ fs = (σ ff + σ ss )/2, and σ ff is the molecular diameter of gas.…”

“…The fugacity of adsorbed gas phase can be calculated by the equation (Fitzgerald et al 2003;Hasanzadeh et al 2010): (17) The covolume b needs to be adjusted for describing the repulsive interaction of adsorbed fluid under high pressure. Then the equation (17) becomes: We used the expression introduced by Chen et al to obtain a ads (z) (Chen et al 1997). By combining equations from (6) to (19), we can compute the density profile ρ(z).…”

Sequestering Carbon Dioxide in Coalbeds

“…Molecular diameters were obtained from Reid [18] and are presented in Table 23. Following Chen [17], the interplanar spacing is 0.335 nm.…”

Sequestering Carbon Dioxide in Coalbeds

“…Molecular diameters were obtained from Reid [16] and are presented in Table 17. Following Chen [15], the interplanar spacing is 0.335 nm.…”

“…The parameter a(z) in the PR EOS is a function of position within the slit when calculating the local phase density for that position. Chen and coworkers [17] provide equations that describe how 'a' changes with position; Table 16 provides these equations, which are necessarily case-dependent on the ratio of the slit length and the fluid molecular diameter σ ff . To obtain these formulas, one integrates the sum of all the two body interactions between an arbitrarily selected central molecule and all the other molecules around it.…”