Adaptive Throat-Sieving Gate in a Metal Azolate Framework Enabling Synergistic Equilibrium-Kinetic Separation of...

Area of Science:

• Materials Science
• Chemical Engineering
• Adsorption Science

Background:

• Propylene/propane (C3H6/C3H8) separation is crucial for petrochemical industries.
• Existing adsorbents struggle to balance high adsorption capacity with fast kinetics.
• Developing advanced materials for efficient gas separation remains a significant challenge.

Purpose of the Study:

• To develop a novel porous adsorbent with integrated high adsorption capacity and fast kinetics for C3H6/C3H8 separation.
• To investigate the structure-performance relationship in a metal azolate framework for selective gas adsorption.
• To demonstrate the practical applicability of the developed adsorbent in C3H6/C3H8 mixture separation.

Main Methods:

• Synthesis and characterization of the metal azolate framework NUM-27a.
• Low-pressure gas adsorption measurements for C3H6 and C3H8.
• Kinetic analysis and gas-loaded single crystal X-ray diffraction.
• Computational simulations to elucidate adsorption mechanisms.
• Breakthrough experiments for C3H6/C3H8 mixture separation.

Main Results:

• NUM-27a exhibits precise pore control with an adaptive throat-sieving gate strategy.
• Exceptional low-pressure C3H6 capture (89.61 cm3 cm-3 at 0.1 bar) and record C3H6 packing density (310.0 g L-1 at 0.01 bar).
• High effective diffusion coefficient for C3H6 (1.57 × 10-4 s-1 at 298 K) and validated separation performance in breakthrough experiments.

Conclusions:

• NUM-27a demonstrates synergistic equilibrium-kinetic separation of C3H6/C3H8 through optimal pore geometry.
• The material shows excellent stability, recyclability, and potential for cost-effective industrial application.
• The adaptive throat-sieving gate strategy offers a promising approach for challenging gas separations.