MOF-5 derived carbon as material for CO(2) absorption.

In our study we prepared MOF-5 derived carbon to reveal the thermodynamics of CO(2) absorption processes in great detail. Porous carbon material was prepared from a metal-organic framework (MOF-5) via carbonization at 1000 °C. The obtained structure consists only of carbon and exhibits a BET specific surface area, total pore volume and micropore volume of 1884 m(2) g(-1), 1.84 cm(3) g(-1) and 0.59 cm(3) g(-1), respectively. Structural analysis allowed the assumption that this material is an ideal candidate for efficient CO(2) absorption. The CO(2) uptake was 2.43 mmol g(-1) at 25 °C and 1 bar. Additionally, the absorption over a wide range of temperatures (25, 40, 60, 80 and 100 °C) and pressures (in range of 0-40 bar) was investigated. It is shown that the CO(2) absorption isotherm fits a multitemperature Sips model. The calculated Sips equation parameters allows the isosteric heat of adsorption to be obtained. The isosteric heat of adsorption for CO(2) decreased substantially with an increase in surface coverage by gas molecules. This indicates a negligible intermolecular interaction between CO(2) molecules. A decrease in the isosteric heat of adsorption with surface coverage is a result of the disappearance of favourable adsorption sites.