Self-assembled Metal−Organic Framework Microspheres for Thermodynamic−Kinetic Synergistic Separation of Propylene and Propane†

Separating propylene (C₃H₆) from propane (C₃H₈) is a complex procedure in the petrochemical sector due to the comparable characteristics of the two gases. Herein, we reported the self-assembly phenomenon of NbOFFIVE-1-Ni (KAUST-7) crystals under different synthetic routes. The material features a decreased framework strain energy compared to original KAUST-7 and exhibits completely different adsorption performance, achieving the efficient separation of C₃H₆/C₃H₈ by synergetic effect of equilibrium and kinetics. The C₃H₆ adsorption capacity was as high as 46.2 cm³·g⁻¹ (298 K, 1 bar), increasing by 53% compared to the original material. The diffusion rates of C₃H₆ were faster than C₃H₈ as confirmed by time dependent kinetic adsorption profiles. It concurrently combines an excellent C₃H₆/C₃H₈ uptake ratio of 3.1 and kinetic selectivity (96.5) for C₃H₆/C₃H₈ separation with an equilibrium-kinetic combined selectivity of 42.5. Meanwhile, it can be regenerated easily due to moderate isosteric heat of adsorption (28.7 kJ·mol⁻¹). Breakthrough experiment for C₃H₆/C₃H₈ gas mixture was conducted and confirmed the high-purity recovery of C₃H₆ over C₃H₈. Moreover, it exhibited excellent water and moisture stability and can be easily synthesized through stirring at room temperature, which confers them with great potential for industrial application.