Experimental and numerical study of CO₂ adsorption on copper benzene-1,3,5-tricarboxylate (Cu-BTC) metal organic framework

The amount and isosteric heat of CO₂ adsorption in copper benzene-1,3,5-tricarboxylate (Cu-BTC) metal organic framework are synchronously experimentally studied with the combined PCTProE&E and Calvet Calorimeter under the ambient temperature of 35 °C and pressure range 0-1200 kPa. A grand canonical Monte Carlo numerical model is proposed to predict the CO₂ adsorption amount combined with isosteric heat. The numerical model is validated with experimental data, and the obtained adsorption snapshots can provide a deep insight for the adsorption structure at molecular level. The CO₂ adsorption amount and heat have three contributions: the Lennard-Jones potential, electrostatic interactions between CO₂ and Cu-BTC, and electrostatic interactions between CO₂ and CO₂. The contribution rate ranges for the adsorption amount of the three mechanisms are 48.45-69.66%, 28.43-48.41%, and 1.91-3.14%, respectively. The third contribution can be ignored. The L-J potential controls the adsorbed CO₂ molecules in the tetrahedron-shaped pockets of Cu-BTC, whereas the electrostatic interactions between CO₂ and Cu-BTC control the adsorbed CO₂ molecules in the larger square-shaped channels of Cu-BTC.