(260c) Sulfonated Polyethersulfone-Based Membranes with Different Ion Forms for High-Performance Gas Separation

Amorphous polymeric materials, which are cost-effective with sufficient selectivity and good processability, are one type of dominating material in the membrane separation technology. It offers the greatest promise for both industrial application and fruitful academic research. However, an issue, namely ?upper bound trade-off curve? raised by Robeson may constrain the further application of polymeric materials in the membrane separation technology. To further expand membranes for industrial applications, one must find ways to improve the gas permeation flux (productivity) and permselectivity by synthesizing and developing high-performance membrane materials.

The sulfonation of polymeric membrane materials is found to be an effective method for advancing membrane-based gas separation performance. Two types of sulfonated polyethersulfone (SPES) polymers with different degrees of sulfonation (DS) were synthesized by adjusting the used amount of chlorosulfonic acid and confirmed via elemental analysis and X-ray photoelectron spectroscopy (XPS) in this work. The SPES-H membranes exhibited a decrease in the permeability and an increase in the selectivity with increasing the degree of sulfonation because of the effect of electrostatic crosslinking. Novel transition metal counterions were applied to conduct the ion exchange treatment of SPES-H polymer samples to change the affinity properties of some specific penetrants in the membrane. The SPES-Zn membrane exhibited the best gas separation performance in this study due to a combination of the strong electrostatic crosslinking and the affinity between Zn2+ and some specific gas molecules. Compared with flat dense PES membranes, the SPES-Zn membrane displayed impressive permselectivity increments of approximately 140%, 86%, 18% and 57% for He/N2, H2/N2, O2/N2 and CO2/CH4 gas pairs, respectively. These newly developed SPES membranes with different ion forms showed high resistance to the CO2-induced plasticization and a comparably high CO2/CH4 selectivity in both pure gas and mixed gas measurements, which demonstrate that these SPES membranes are a type of potential and excellent membrane material for gas separation in industrial applications.