MONTE CARLO SIMULATIONS OF NITROGEN AND HYDROGEN PHYSISORPTION AT HIGH PRESSURES AND ROOM TEMPERATURE. COMPARISON WITH EXPERIMENTS

The excess surface adsorptions of nitrogen and hydrogen gases on graphite basal planes at a temperature of 293 K have been computed by numerical simulations. The results of the simulations are compared to experimental data on the adsorption of these two gases measured on activated carbons. The adsorption isotherms have been calculated up to 600 MPa, and the experimental isotherms have been measured in the pressure range from 0 to 500 MPa for nitrogen gas and up to 60 MPa for hydrogen gas. Both theoretical and experimental nitrogen adsorption isotherms have similar shapes. They present a maximum at moderate pressures, then decrease toward a constant value or a shallow minimum followed by a slight increase at very high pressures. In addition, we compare the values of the hydrogen adsorption computed by simulation at a temperature of 77 K and low pressures with those recently measured. The qualitative agreement between experimental and simulations results is rather good for both gases at the temperatures con...