Surface Modification of Polyimide Membranes by Diamines for H₂ and CO₂ Separation

Abstract

Summary: The separation of H2/CO2 is technologically important to produce the next generation fuel source, hydrogen, from synthesis gas. However, the separation efficiency achieved by polymeric membranes is usually very low because of both unfavourable diffusivity selectivity and solubility selectivity between H2 and CO2. A series of novel diamino‐modified polyimides has been discovered to enhance the separation capability of polyimide membranes especially for H2 and CO2 separation. Both pure gas and mixed gas tests have been conducted. The ideal H2/CO2 selectivity in pure gas tests is 101, which is far superior to other polymeric membranes and is well above the Robeson's upper‐bound curve. Mixed gas tests show an ideal selectivity of 42 for the propane‐1,3‐diamine‐modified polyimide. The lower selectivity is a result of the sorption competition between H2 and the highly condensable CO2 molecules. However, both pure gas and mixed gas data are better than other polymeric membranes and above the Robeson's upper‐bound curve. It is evident that the proposed modification methods can alter the physicochemical structure of polyimide membranes with superior separation performance for H2 and CO2 separation.

Biohydrogen purification using a commercial polyimide membrane module: Studying the effects of some process variables

“…If comparing the result to the previously determined theoretical values of the membrane module at different temperatures [30], it would appear that the real separation factors have declined in a remarkable degree. Similar observations were reported in other studies, as well [22,31].…”

Polymeric membranes for the purification of hydrogen

“…For instance, the 6FDA-DDBT polyimide exhibits H 2 permeability of 156 Barrer and H 2 /CH 4 selectivity of 80 (Li, Zhu, Ratinac, Ringer, & Wang, 2009), whereas the nonfluorinated BPDA-ODA polyimide has H 2 permeability of 1.33 Barrer and H 2 /N 2 selectivity of 370 (Li, Wang, Ding, & Xu, 1996;Yampolskii, 2012). Diamino-modified polyimides have an ideal H 2 /CO 2 selectivity of 101, which is far superior to other polymeric membranes and is well above the Robeson's upper-bound line (Chung, Shao, & Tin, 2006).…”

A Review on the Production and Purification of Biomass-Derived Hydrogen Using Emerging Membrane Technologies

“…Chung's group is the pioneer of exploring the crosslinking post-treatment of polyimide membranes for gas separation [58][59][60]. According to their reports, the H 2 /CO 2 selectivity of the modified polyimide membrane could be significantly increased by over 100 times upon crosslinking with 1,3-diaminopropane (PDA) at 35 • C for only 10 min [61]. However, this crosslinking process also resulted in a significant reduction of hydrogen permeability [58][59][60][61] because of increased resistance through the membranes after the polymer chain was restricted.…”