Boosting kinetic separation of ethylene and ethane on microporous materials via crystal size control

Abstract

The adsorptive separation of C2H4 and C2H6, as an alternative to distillation units consuming high energy, is a promising yet challenging research. The great similarity in the molecular size of C2H4 and C2H6 brings challenges to the regulation of adsorbents to realize efficient dynamic separation. Herein, we reported the enhancement of the kinetic separation of C2H4/C2H6 by controlling the crystal size of ZnAtzPO4 (Atz = 3-amino-1,2,4-triazole) to amplify the diffusion difference of C2H4 and C2H6. Through adjusting the synthesis temperature, reactant concentration, and ligands/metal ions molar ratio, ZnAtzPO4 crystals with different sizes were obtained. Both single-component kinetic adsorption tests and binary-component dynamic breakthrough experiments confirmed the enhancement of the dynamic separation of C2H4/C2H6 with the increase in the crystal size of ZnAtzPO4. The separation selectivity of C2H4/C2H6 increased from 1.3 to 98.5 with the increase in the crystal size of ZnAtzPO4. This work demonstrated the role of morphology and size control of adsorbent crystals in the improvement of the C2H4/C2H6 kinetic separation performance.