Preparation of HKUST-1/PEI mixed-matrix membranes: Adsorption-diffusion coupling control of small gas molecules

HKUST-1 nanocrystals (50-80 nm) were homogeneously dispersed in a polyetherimide (PEI) polymer matrix. The use of a capping agent (sodium formate) prevented the agglomeration of HKUST-1 nanocrystals in the casting solution. The highly dispersed HKUST-1 nanocrystals were found to strengthen the interactions with the PEI and minimize the interfacial holes by providing more accessible Cu unsaturated metal sites for the C=O bonds on the five-membered rings of the PEI matrix. The PEI membrane loaded with 30 wt % HKUST-1 nanocrystals (30-N-HKUST-1/PEI) showed a high H-2 permeability (193.3 Barrer at 25 degrees C under 1.5 bar) and good ideal H-2/CH4 and H-2/CO2 selectivity factor of 101.7 and 20.6 in a single gas test, respectively. In the gas mixture test, it also showed a good separation performance, i.e., a H-2/CH4 and H-2/CO2 selectivity factor of 82.4 and 16.5 was measured, respectively. The 30-N-HKUST/PEI membrane was tested in a gas mixture at different temperatures (25-100 degrees C), different pressures (0-3 bar) and various time (5-72 h) to study the performance in more realistic conditions thus to be further considered in the separation of syngas.

Automated summary

HKUST-1 nanocrystals were dispersed in a PEI polymer matrix with the use of a capping agent to prevent agglomeration. The highly dispersed nanocrystals strengthened interactions with PEI, leading to improved gas separation performance. Testing under various conditions showed potential for future applications in syngas separation.