Ultrafine tuning of the pore size in zeolite A for efficient propyne removal from propylene

The removal of trace propyne (C₃H₄) from propyne/propylene (C₃H₄/C₃H₆) mixtures is a technical and challenging task during the production of polymer-grade propylene in view of their very similar size and physical properties. While some progress has been made, it is still very challenging to use some highly stable and commercially available porous materials via an energy-efficient adsorptive separation process. Herein, we report the ultrafine tuning of the pore apertures in type-A zeolites for the highly efficient removal of trace amounts of C₃H₄ from C₃H₄/C₃H₆ mixtures. The resulting ion-exchanged zeolite 5A exhibits a large C₃H4 adsorption capacity (2.3 mmolg^-1 under 10^-4 MPa) and high C₃H₄/C₃H₆ selectivity at room temperature, which were mainly attributed to the ultrafine-tuned pore size that selectively blocks C₃H₆ molecules, while maintaining the strong adsorption of C3H4 at low pressure region. High purity of C₃H₆ (>99.9999 can be directly obtained on this material under ambient conditions, as demonstrated by the experimental breakthrough curves obtained for both 1/99 and 0.1/99.9 (V/V) C₃H₄/C₃H₆ mixtures.