Modification of the pore environment in UiO-type metal-organic framework toward boosting the separation of propane/propylene

The separation of propane (C 3 H 8 ) from propylene (C 3 H 6 ) to obtain high purity C 3 H 6 as a petrochemical raw material is an important, but challenging process. In the traditional industrial process, the separation mainly relies on energy-intensive cryogenic distillation. One alternative process that is currently becoming more attractive in the separation of C 3 H 6 is adsorptive separation technology. Using porous materials, especially C 3 H 8 selective adsorbents, high purity C 3 H 6 can be directly obtained and thus, significantly simplifies the process. Herein, a series of functionalized ligands were introduced into UiO-type materials to finely regulate the C 3 H 8 separation performance. Single-component adsorption isotherms reveal that BUT-10 has a distinct binding affinity for C 3 H 8 over C 3 H 6 over a wide range of temperature from 298 to 338 K and thus, achieved by far the highest C 3 H 8 capture capacity (105 cm 3 g −1 at 0.1 bar and 298 K) reported among the C 3 H 8 -selective materials reported to date. A combination of Grand Canonical Monte Carlo and density-function theory simulations demonstrate that the favorable pore environment provided by the multiple host-guest interactions toward C 3 H 8 result in the higher C 3 H 8 binding affinity observed in the separation process. Breakthrough experiments indicate that BUT-10 can selectively separate C 3 H 8 from C 3 H 8 /C 3 H 6 (1/1 and 1/15, v/v) mixtures and thus, directly produces high purity C 3 H 6 (>99.99%) under ambient conditions.