1,3-Propane Diamine/1,4-Butane Diamine Cross-linking Modification of Polyimide Membrane for Hydrogen Selective Separation: Effect of Diamine Mixture Ratio

Hydrogen (H-2) can be produced through biomass processing which involved lower energy requirement and production cost. It is produced as biohydrogen (bio-H-2) together with carbon dioxide in biogas so it is essential to purify H-2 for utilization. Membrane gas separation is a promising technology for H-2 purification. However, current separation efficiency of commercial polymeric membrane is insufficient to achieve industrial demand. Crosslinking diamine modification has been discovered to enhance separation performance of membrane in terms of permeability and selectivity. Gas separation effectiveness of mixed crosslinking agent on polyimide (PI) membrane is studied in this research by blending PDA and BuDA with different concentration. PI membrane is fabricated with phase inversion method with different weight percentage of PI in polymer solution. The chemical modification by immersing in mixed PDA-BuDA crosslinking solution for 5 minutes reaction times. Pure gas test has been conducted for separation performance andchemical structure changes were monitored by FTIR. It is found that H-2/CO2 selectivity increased significantly and H-2 permeability decreased dramatically with higher concentration of PDA in crosslinking solution. Membrane with 8:2 ratio of PDA-BuDA solution achieved highest H-2/CO2 selectivity from 3.7 to 7.8 compared to other ratio of PDA-BuDA solution.