The analysis of adsorption isotherms was based on the calculation of differential distributions of the amount adsorbed with respect to the adsorption potential.
It appears that the filling of Cu-BTC micro pores with nitrogen occurs in two steps due to specific interaction of nitrogen molecules with open metal sites. In contrast to nitrogen,the filling of Cu-BTC micro pores with argon takes place in one step.
The micro pores of Fe-BTC are filled with nitrogen and argon gradually in two featureless stages indicating the unordered porous structure.
Calculated isosteric adsorption heats suggest that the energy of lateral interactions between adsorbed molecules dominates the gas–solidenergy heterogeneity.
Fe-BTC show one saturation step being less sharp than in the case of Cu-BTC.
This domination is especially pronounced for cyclopentane adsorbed on Cu-BTC
In the case of Fe-BTC almost constant isosteric adsorption heats show that the variations of the gas–solid interaction energy are compensated by the energy of lateral interactions