Development of Novel active transport membrane devices. Phase I. Final report, 31 October 1988--31 January 1994

The main objective of this program was to identify and develop a technique for fabricating Active Transport Materials (ATM) into lab-scale membrane devices. Air Products met this objective by applying thin film, multilayer fabrication techniques to support the AT material on a substrate membrane. In Phase IA, spiral-wound hollow fiber membrane modules were fabricated and evaluated. These nonoptimized devices were used to demonstrate the AT-based separation of carbon dioxide from methane, hydrogen sulfide from methane, and ammonia from hydrogen. It was determined that a need exists for a more cost efficient and less energy intensive process for upgrading subquality natural gas. Air Products estimated the effectiveness of ATM for this application and concluded that an optimized ATM system could compete effectively with both conventional acid gas scrubbing technology and current membrane technology. In addition, the optimized ATM system would have lower methane loss and consume less energy than current alternative processes. Air Products made significant progress toward the ultimate goal of commercializing an advanced membrane for upgrading subquality natural gas. The laboratory program focused on developing a high performance hollow fiber substrate and fabricating and evaluating ATM-coated lab-scale hollow fiber membrane modules. Selection criteria for hollow fiber composite membrane supports were developed and used to evaluate candidate polymer compositions. A poly(amide-imide), PAI, was identified for further study. Conditions were identified which produced microporous PAI support membrane with tunable surface porosity in the range 100-1000{Angstrom}. The support fibers exhibited good hydrocarbon resistance and acceptable tensile strength though a higher elongation may ultimately be desirable. ATM materials were coated onto commercial and PAI substrate fiber. Modules containing 1-50 fibers were evaluated for permselectivity, pressure stability, and lifetime