Thermodynamic and kinetic synergetic separation of CO2/C2H2 in an ultramicroporous metal-organic framework

The selective removal of carbon dioxide (CO 2 ) from acetylene (C 2 H 2 ) is an important separation process in the petrochemical industry, but is challenging due to the similar physicochemical properties of the two gases. Using CO 2 -selective adsorbents that have preferential affinity for CO 2 over C 2 H 2 in pressure swing adsorption was deemed a promising separation method for the separation of CO 2 /C 2 H 2 mixtures. Herein, we report an ultramicroporous metal-organic framework, Y-bptc, to achieve efficient separation of CO 2 /C 2 H 2 through thermodynamic and kinetic synergetic effects. The unique cage-type structure interconnected by small windows exhibits high adsorption capacity for CO 2 while efficiently impeding adsorption diffusion of C 2 H 2 , which was proved by the single-component equilibrium and kinetic adsorption curves. Grand canonical Monte Carlo (GCMC) molecular calculations further show that the µ 3 -OH − of the framework have a stronger adsorption affinity for CO 2 through forming hydrogen bonds. Breakthrough experiments using Y-bptc as a CO 2 -selective adsorbent proved that high-purity C 2 H 2 (>99%) could be directly produced from one-step separation of CO 2 /C 2 H 2 (1/1, v/v) mixtures, which greatly reduced the separation process and energy consumption. In addition, the structure of Y-bptc due to the high charge density of the Y6 cluster has high stability under humid and high-temperature conditions adding to the application possibility in industry.