Ning Li,Chao Ma,Ziyue Wang,Dudu Li,Zhihua Qiao,Chongli Zhong
The MOF crystal-glass composites (CGC) membrane, comprising a MOF crystal and MOF glass matrix, represents a novel self-supported membrane that has been effectively applied in gas separation. Nevertheless, the typical MOF glass matrix requires a higher operating temperature (>400 °C), which constrains its combination with a multitude of MOF crystals characterized by high porosity and low decomposition. In this work, Zn-P-dmbIm (coordination polymer) was chosen as the glass matrix, and MIL-101 crystal with high porosity were integrated at an operating temperature of 190 °C. Furthermore, the intrinsic low porosity of a g Zn-P-dmbIm can be enhanced by the incorporation of higher porosity MIL-101, which possessed a high specific surface area (from ∼1.7 m 2 /g to 401 m 2 /g) and porosity (from ∼0.0014 cm³/g/nm to 0.5605 cm³/g/nm) of the CGC. The intimate combination of MIL-101 and a g Zn-P-dmbIm by in - situ melting to reduce the interfacial defects, which also provides a robust foundation for effective CO 2 /N 2 separation. In CO₂/N₂ (50/50, v/v) mixed gas conditions, the MIL-101/ a g Zn-P-dmbIm membrane demonstrated a impressively high CO₂ permeability of 18670 barrer and CO₂/N₂ selectivity of 61, exceeding the CO₂/N₂ upper bound. The variable pressure (1-12 bar) and long-term stability (120 h) of the CGC membrane exhibited enhancing separation stability. Hence, the self-supported MIL-101/ a g Zn-P-dmbIm membrane demonstrated effective CO₂/N₂ separation performance, which had the potential to significantly extend the scope of applications for MOF crystal-glass matrices.
Metal-organic framework glass shows great promise in gas separation applications, however, its inherent low porosity poses significant challenges to achieve the enhanced membrane permeability. In this work, we developed novel self-standing crystal-glass composite membrane via melt quenching process of porous organic cages and coordination polymer glasses. The resulting (CC3) n /( a g Zn-P-dmbIm) 1-n membranes effectively combines the high porosity of CC3 with the excellent film-forming property of Zn–P-dmbIm glass, enabling efficient CO 2 /CH 4 separation. Specifically, CO 2 molecules are preferentially adsorbed into the CC3 channels, followed by rapid permeation through the membrane, while the size exclusion restricts CH 4 molecules transport through the membranes. The obtained (CC3) 0.05 /( a g Zn-P-dmbIm) 0.95 membrane achieves a high CO 2 permeability of 9358 Barrer, a CO 2 /CH 4 selectivity of 24.2, and demonstrates 24-h operational stability. This study not only broadens the application scope of coordination polymer glasses in gas separation membranes but also provides novel insights for the design of high-performance crystal-glass composite membranes.
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