Methane Adsorption in Microporous Carbon Adsorbent with a Bimodal Pore Size Distribution.

Methane adsorption in MPU-007 microporous carbon adsorbent with a wide pore size distribution was studied at a pressure as high as 40 MPa and the temperatures of 303, 313, 323, and 333 K. The maximum value of methane adsorption of 43.36 wt % was achieved at 303 K and 40 MPa. The isosteres of adsorption derived from the obtained data were satisfactorily approximated by a linear function in coordinates ln P–1/Т at a constant value of adsorption. The dependences of differential molar isosteric heats of methane adsorption in MPU-007 microporous adsorbent on the value of methane adsorption were calculated at the temperatures of 303, 313, 323, and 333 K. The heat of methane adsorption of 14 kJ/mol was constant at a filling of micropores as low as ≈5 mmol/g. Then it declined evenly to 8 kJ/mol at 25 mmol/g and 303 K and to 2 kJ/mol at 24 mmol/g and 323 K. Such a run of the curves describing the heats of adsorption versus adsorption value might be caused by a wide pore size distribution and the association processes in the adsorbate. [ABSTRACT FROM AUTHOR]