Propane-Trapping Ultramicroporous Metal-Organic Framework in the Low-Pressure Area toward the Purification of Propylene.

The propane (C3H8)-trapping adsorption behavior is considered as a potential performance to directly produce high-purity propylene (C3H6). Herein, we report an ultramicroporous Mn-based metal-organic framework (NUM-7) with a reverse C3H8-selective behavior in the low-pressure area. The pore structure of this material possesses more electronegative aromatic benzene rings for the stronger binding affinity to C3H8, and the material shows outstanding reverse ideal adsorbed solution theory (IAST) selectivity values. Single-component sorption isotherms preliminarily show the reverse adsorption behavior in the low-pressure part, and the moderate heat of adsorption further confirms this performance and exhibits less energy consumption for regeneration. In addition, the purification effect for the C3H8/C3H6 mixture is evaluated by the IAST selectivity and transient breakthrough curves, and the GCMC calculation results reveal that the fascinating C3H8-trapping behavior mainly depends on the multiple C-H···π interactions. Moreover, because C3H6 is the desired target product, the interesting C3H8-selective adsorption behavior of NUM-7 may provide its potential for one-step purification of C3H6, and this work can provide the method of developing C3H8-selective materials for the purification of C3H6.