Adsorption and Separation of CO2/CH4 on Amorphous Silica Molecular Sieve

Adsorption and separation of CO 2 /CH 4 were examined on two kinds of amorphous silica molecular sieves, ASMS-3A and ASMS-5A, that are composed of spherical cavities arranged in a face-centered-cubic array and connected through narrow necks of molecular dimensions. For ASMS-3A, the exclusion of CH 4 molecules due to their dimensions into the narrow necks and preferential adsorption of CO 2 with the smaller kinetic diameter is observed at 283 K. In addition, the amount of CO 2 adsorbed at 283 K does not decrease at all with surface hydration. All these results suggest that ASMS-3A is a promising candidate for the separation and purification of CO 2 from various CO 2 /CH 4 mixtures such as natural gas and landfill gas by a PSA process.