Highly selective separation of C3H6/C3H8 within hierarchical metal–organic CuxOy@HP–Cu–BTCs

Two critical characteristics for gas adsorption and separation are the porosity and open metal sites of adsorbents. The Cu–BTC (BTC = benzene–1,3,5–tricarboxylate) structure was tailored using a template synthesis technique to increase the separation performance for C3H6/C3H8 mixtures. The three hierarchical porous frameworks, CuxOy@HP–Cu–BTC, synthesized using a cationic surfactant (cetyltrimethylammonium bromide (CTAB)), a neutral organic amine (N,N–dimethyltetradecylamine (N,N)), and an anionic surfactant (sodium dodecylbenzene sulfonate (SDBS)) as the template, CuxOy@HP–Cu–BTC(SDBS) exhibited the best performance, with a C3H6 adsorption capacity of 6.679 mmol g−1, which was significantly greater than that of C3H8 (5.721 mmol g−1). CuxOy@HP–Cu–BTC(SDBS) has an ideal ultra–microporous structure that encloses C3H6 molecules precisely while rejecting slightly bigger C3H8 molecules, and C3H6 interacts strongly with unsaturated metal sites through particular π–Cu bonds. According to the ideal adsorbed solution theory (IAST), the adsorption selectivity of C3H6/C3H8 was 63.322, which is more than that of the reference adsorbent Cu–BTC. Additionally, the breakthrough studies shown that CuxOy@HP–Cu–BTC(SDBS) has a good dynamic performance for the effective separation of the C3H6/C3H8 mixture.