Adsorption of CO₂, CH₄, CO₂/N₂ and CO₂/CH₄ in novel activated carbon beads: Preparation, measurements and simulation

Abstract

A series of high performance carbonaceous mesoporous materials: activated carbon beads (ACBs), have been prepared in this work. Among the samples, ACB-5 possesses the BET specific surface area of 3537 m² g⁻¹ and ACB-2 has the pore volume of 3.18 cm³ g⁻¹. Experimental measurements were carried out on the intelligent gravimetric analyzer (IGA-003, Hiden). Carbon dioxide adsorption capacity of 909 mg g⁻¹ has been achieved in ACB-5 at 298 K and 18 bar, which is superior to the existing carbonaceous porous materials and comparable to metal-organic framework (MOF)-177 (1232 mg g⁻¹, at 298 K and 20 bar) and covalent-organic framework (COF)-102 (1050 mg g⁻¹ at 298 K and 20 bar) reported in the literature. Moreover, methane uptake reaches 15.23 wt % in ACB-5 at 298 K and 18 bar, which is better than MOF-5. To predict the performances of the samples ACB-2 and ACB-5 at high pressures, modeling of the samples and grand canonical Monte Carlo simulation have been conducted, as is presented in our previous work. The adsorption isotherms of CO₂/N₂ and CO₂/CH₄ in our samples ACB-2 and 5 have been measured at 298 and 348 K and different compositions, corresponding to the pre- and postcombustion conditions for CO₂ capture. The Dual-Site Langmuir-Freundlich (DSLF) model-based ideal-adsorbed solution theory (IAST) was also used to solve the selectivity of CO₂ over N₂ and CH₄. The selectivities of ACBs for CO₂/CH₄ are in the range of 2–2.5, while they remain in the range of 6.0–8.0 for CO₂/N₂ at T = 298 K. In summary, this work presents a new type of adsorbent-ACBs, which are not only good candidates for CO₂ and CH₄ storage but also for the capture of carbon dioxide in pre- and postcombustion processes. © 2011 American Institute of Chemical Engineers AIChE J, 2011