Impact of tailored textural properties of activated carbons on methane storage

Abstract Taking care of our environment, we focused our studies on the possibility of modification of commercial activated carbons to obtain the materials for CH4 storage. An innovative and inexpensive method of tailoring of textural properties of the activated carbons for a considerable increase of their porosity and the CH4 capture was investigated. The activated carbons FPV, WG-12, and CWZ-22, purchased from GRYFSKAND Ltd. (Poland), were utilized as a starting material, and KOH and K2CO3 were used as modification agents. The modification temperature was varied over the range of 600 °C to 850 °C, and the ratio of modification agent to carbon from 1 to 4 was examined. This forward-looking and straightforward method of improving texture properties provides excellent potential for the materials obtained in the CH4 storage process. Dozens of experiments have been determined in the temperature range from 25 °C to 160 °C under pressure up to 40 bar. It has been demonstrated that the largest CH4 adsorption capacity equals to 9.7 mmol/g under the pressure of 35 bar at temperature 25 °C attained the FPV carbon modified by KOH at the mass ratio of KOH to carbon equal to 4. A close correlation between the magnitude of CH4 adsorption under pressure of 35 bar at temperature 25 °C and the microporosity of the activated carbons, or strictly speaking, the specific surface area, was found. The best fitting to the experimental data was achieved with the application of the Sips equation. The isosteric heats of adsorption were also calculated.