Adsorption of Pure and Binary CO₂, CH₄, and N₂ Gas Components on Activated Carbon Beads

Abstract

The adsorption equilibriums of CO 2, CH 4, and N 2 pure gases on pitch-based activated carbon beads have been studied using a magnetic suspension microbalance at (293, 303, 333, and 363) K within a pressure range of 0 kPa to 4000 kPa. It is found that experimental adsorption capacities can be successfully described with both the Sips and Multisite Langmuir (MSL) isotherm models. Afterward, binary competitive adsorption breakthrough experiments (CO 2 /CH 4 and CH 4 /N 2 ) at 303 K and adsorption isotherms of gas mixtures under different conditions have been measured. Theoretical calculations from Sips model-based ideal adsorbed solution theory are found to have better agreement with experimental data of competitive binary adsorption than that from MSL model. Promising adsorption selectivity (5.5) between CH 4 and N 2 is obtained at 303 K as the pressure of a binary gas mixture is 100 kPa with y CH4 = 0.5 in the feed. Therefore, the activated carbon beads reported in this study can be considered as a promising adsorbent for CH 4 enrichment from coalbed methane (CH 4 /N 2 ) gas mixture.