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

Abstract

The separation of propane (C3H8) from propylene (C3H6) to obtain high purity C3H6 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 C3H6 is adsorptive separation technology. Using porous materials, especially C3H8 selective adsorbents, high purity C3H6 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 C3H8 separation performance. Single-component adsorption isotherms reveal that BUT-10 has a distinct binding affinity for C3H8 over C3H6 over a wide range of temperature from 298 to 338 K and thus, achieved by far the highest C3H8 capture capacity (105 cm3 g−1 at 0.1 bar and 298 K) reported among the C3H8-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 C3H8 result in the higher C3H8 binding affinity observed in the separation process. Breakthrough experiments indicate that BUT-10 can selectively separate C3H8 from C3H8/C3H6 (1/1 and 1/15, v/v) mixtures and thus, directly produces high purity C3H6 (>99.99%) under ambient conditions.