Ethylene-Ethane Molecular Sieving with CDO Zeolite: Adsorption Equilibrium, Kinetics, and Dynamics

Molecular sieving in zeolites has been applied in a wide array of catalytic and separation applications for the chemical and energy sectors. Within these industries, olefin-paraffin separations remain a challenging area for reducing energy consumption due to cryogenic distillation trains for purification of olefins for petrochemicals. Very few nanoporous materials to-date have shown the ability to kinetically separate ethylene from ethane, two molecules separated by tenths of an angstrom in kinetic diameter. Here, it is shown that a pure-silica zeolite framework with the CDO topology is capable of molecular sieving ethylene from ethane. It is found that the synthesis approach may affect the measured adsorption and diffusion properties of the zeolite. Equilibrium and kinetic adsorption measurements on pure component gases show ideal adsorption selectivity of 1.4 to 1.8 and diffusion ratio selectivity exceeding 40 and 130, depending on the synthesis conditions. Adsorption measurements are analyzed by sequential Monte Carlo methods to estimate adsorption equilibrium and kinetics parameters of each synthesis method. Dynamic adsorption measurements demonstrate the ability to separate ethylene from ethane in a multicomponent gas mixture.