Effect of aggressive gas on separation properties of carbon molecular sieve hollow fiber membranes

Abstract

A practical membrane separation process is considered in this study for removal of CO2 from natural gas in the presence of H2S. Carbon molecular sieve (CMS) materials derived from Matrimid® and 6FDA:BPDA-DAM have been used for this particular separation. Optimization of V-treatment for CMS has been done in this study to prevent collapse of the substructure of polymer hollow fibers upon pyrolysis. Most importantly, this treatment was proven that this method is scalable. Details of interaction of H2S with CMS membranes were also clarified in this work and found to be different for CMS starting from different precursors. In addition to the measured changes in transport performance, analytical characterization techniques proved that H2S conditions CMS membranes by chemical interaction. The H2S conditioning led to a permanently reduced permeance through the CMS membrane, thereby making the membrane less attractive for industrial use. To prevent this poisoning, a novel method, called chlorine fixation, for neutralizing the reactive edges of the CMS was explored. The study has benchmarked the performance of CMS membranes in a sour gas feed. This work has established a framework for providing a potentially practical hollow fiber membrane technology for aggressive gas separation.