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 C 3 H 6 /C 3 H 8 mixtures. The three hierarchical porous frameworks, Cu x O y @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, Cu x O y @HP–Cu–BTC(SDBS) exhibited the best performance, with a C 3 H 6 adsorption capacity of 6.679 mmol·g −1 , which was significantly greater than that of C 3 H 8 (5.721 mmol·g −1 ). Cu x O y @HP–Cu–BTC(SDBS) has an ideal ultra–microporous structure that encloses C 3 H 6 molecules precisely while rejecting slightly bigger C 3 H 8 molecules, and C 3 H 6 interacts strongly with unsaturated metal sites through particular π–Cu bonds. According to the ideal adsorbed solution theory (IAST), the adsorption selectivity of C 3 H 6 /C 3 H 8 was 63.322, which is more than that of the reference adsorbent Cu–BTC. Additionally, the breakthrough studies shown that Cu x O y @HP–Cu–BTC(SDBS) has a good dynamic performance for the effective separation of the C 3 H 6 /C 3 H 8 mixture. Single–gas adsorption isotherm measurements showed that the C 3 H 6 adsorption capacity of Cu x O y @HP–Cu–BTC(SDBS) was enhanced owing to the presence of multi–level channels (ultra–microporous, microporous, and mesoporous) and π–complexation between Cu + and propylene. Moreover, Cu x O y @HP–Cu–BTC(SDBS) showed higher adsorption capacities for C 3 H 6 (6.679 mmol·g −1 ) than for C 3 H 8 (5.721 mmol·g −1 ) at 273 K and 100 kPa. The corresponding adsorption selectivity of C 3 H 6 /C 3 H 8 predicted by the ideal adsorbed solution theory (IAST) was 63.322 at 313 K and low surface coverage outperforming some popular MOFs. Furthermore, the breakthrough experiment results showed favorable dynamic performance of Cu x O y @HP–Cu–BTC(SDBS) for the efficient separation of C 3 H 6 /C 3 H 8 binary gas mixtures. • Cu x O y @HP-Cu-BT with tunable porosity, high pore volume, and open Cu + sites synthesized. • Cu x O y @HP-Cu-BTC(SDBS) showed optimum C 3 H 6 saturated adsorption capacity. • C 3 H 6 /C 3 H 8 adsorption selectivity was 63.322 at 313 K and low surface coverage. • DSS model fitted the equilibrium adsorption data well. • New strategy to synthesize Cu x O y @HP-Cu-BTC for separation of light hydrocarbon and CO 2 .