Superhydrophobic zeolitic imidazolate framework with suitable SOD cage for effective CH4/N-2 adsorptive separation in humid environments

Various adsorbents for CH4/N-2 separation were developed to enrich low-concentration coal-mine methane. Most are hydrophilic and cannot treat moist coal-mine methane. We report for the first time a microporous zeolitic imidazolate framework Co(dcIm)(2) (TUT-100) with superhydrophobic properties for CH4/N-2 separation. The CH4 adsorption capacity and CH4/N-2 selectivity were as high as 45.29 cm(3)/cm(3) and 6.3 (298 K, 1 bar), respectively, which results from the suitable SOD cage size (0.80 nm). The H2O adsorption was lower than 6.3 cm(3)/g at 298 K and near saturated pressure due to the hydrophobic group -Cl. Breakthrough experiments were carried out to indicate the significant potential for CH4/N-2 adsorption separation in a humid environment. The adsorption behavior of the gas mixture on the TUT-100 was investigated by the Grand Canonical Monte Carlo method and coupled with the experimental data.