Continuous Porous Aromatic Framework Membranes with Modifiable Sites for Optimized Gas Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Membrane Technology

Background:

• Continuous microporous membranes are crucial for energy-efficient gas separation due to their molecular specificity.
• Porous aromatic frameworks (PAFs) offer stability and flexibility for separations but are challenging to synthesize into continuous membranes due to insolubility.
• Existing PAF membranes often use polymeric matrices, leading to defects that compromise selectivity and permeability.

Purpose of the Study:

• To develop a continuous porous aromatic framework (PAF) membrane for gas separation.
• To investigate the effect of ion-exchange modification on the membrane's pore size and chemistry.
• To evaluate the performance of the modified PAF membrane for H2/N2 and CO2/N2 gas mixtures.

Main Methods:

• Synthesis of a continuous PAF membrane.
• Modification of pore size and chemistry via ion-exchange using Br- and BF4- counter ions.
• Gas permeation and selectivity measurements for H2/N2 and CO2/N2 mixtures.

Main Results:

• The synthesized continuous PAF membrane demonstrated tunable properties through ion-exchange.
• The Br- modified membrane achieved a H2/N2 selectivity of 72.7 with a H2 permeance of 51844 GPU.
• The BF4- modified membrane exhibited a CO2/N2 selectivity of 60.0 with a CO2 permeance of 23058 GPU.

Conclusions:

• Continuous PAF membranes with ion-exchange-modifiable pores are highly promising for gas separation.
• The developed membranes show excellent selectivity and permeance for industrially relevant gas mixtures.
• This approach offers a viable pathway for creating advanced membranes for diverse separation applications.