H2, N2, CO2, and CH4 Unary Adsorption Isotherm Measurements at Low and High Pressures on Zeolitic Imidazolate Framework ZIF-8

Excess adsorption of CO2, CH4, N-2, and H-2 on ZIF-8 was measured gravimetrically in the pressure range ranging from vacuum to 30 MPa at 298.15, 313.15, 333.15, 353.15, and 394.15 K using a magnetic suspension balance. The textural properties of the adsorbent material-i.e., skeletal density, surface area, pore volume, and pore-size distribution-were estimated by helium gravimetry and N-2 (77 K) physisorption. The adsorption isotherms were fitted with the Sips isotherm model and the virial equation, and the values of isosteric heat of adsorption and Henry constants for the gases were determined using the latter.