Synthesis and characterization of 6FDA/3,5-diamino-2,4,6-trimethylbenzenesulfonic acid-derived polyimide for gas separation applications
KAUST DepartmentFunctional Polymer Membranes Group, Advanced Membranes and Porous Materials Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
Advanced Membranes and Porous Materials Research Center
Physical Science and Engineering (PSE) Division
Biological and Environmental Sciences and Engineering (BESE) Division
Chemical Engineering Program
KAUST Grant NumberBAS/1/1323-01-01
Online Publication Date2020-10-23
Print Publication Date2021-02
Embargo End Date2021-10-23
Permanent link to this recordhttp://hdl.handle.net/10754/665774
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AbstractA sulfonic acid-functionalized trimethyl-substituted polyimide was synthesized by reacting 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 3,5-diamino-2,4,6-trimethylbenzenesulfonic acid (TrMSA). The properties of 6FDA-TrMSA were compared to the related 6FDA-derived polyimide analogues made from 2,4,6-trimethylbenzene-1,3-diamine (6FDA-TrMPD) and 3,5-diamino-2,4,6-trimethylbenzene benzoic acid (6FDA-TrMCA). Compared to 6FDA-TrMPD and 6FDA-TrMCA, sulfonic acid functionalization resulted in significantly lower surface area, reduced fractional free volume, and tighter chain d-spacing. Consequently, 6FDA-TrMSA displayed lower gas permeabilities with a commensurate increase in permeability-based gas-pair selectivities. The enhanced CO2/CH4 selectivity of 6FDA-TrMSA was caused exclusively by higher diffusion selectivity, which was promoted by strong hydrogen bonding induced by the [sbnd]SO3H functionalization. Permeation experiments of 6FDA-TrMSA with a 1:1 CO2-CH4 mixture revealed the occurrence of competitive sorption effects (depressing CO2 gas permeability) and CO2-induced polymer matrix plasticization, which reduced the polymer selectivity by enhancing CH4 permeability. At ~20 atm total pressure, 6FDA-TrMSA showed a CO2 permeability of ~15 Barrer and an equimolar CO2/CH4 mixed-gas selectivity of 55, which are ~2-fold higher performance values than those of the state-of-the-art polymer used for industrial scale natural gas sweetening, i.e., cellulose triacetate.
CitationAbdulhamid, M. A., Genduso, G., Ma, X., & Pinnau, I. (2021). Synthesis and characterization of 6FDA/3,5-diamino-2,4,6-trimethylbenzenesulfonic acid-derived polyimide for gas separation applications. Separation and Purification Technology, 257, 117910. doi:10.1016/j.seppur.2020.117910
SponsorsThis work was supported by funding from King Abdullah University of Science and Technology (BAS/1/1323-01-01).