NASA 1996 SBIR Phase I

PROJECT TITLE : Lightweight CO2 Removal via Stable Facilitated Transport Membranes

TECHNICAL ABSTRACT (LIMIT 200 WORDS)

Current technology for CO2 removal from the enclosed air of spacecraft utilizes LiOH canisters for CO2 absorption. This system requires that the canisters be manually changed every 11 hours and could add as much as 1000 pounds of weight over the course of a 30 day space flight. We propose a lightweight, small volume, and maintenance-free system of CO2 removal based on facilitated transport membranes (FTMs). FTMs are known for being remarkably selective and highly permeable at low concentration driving forces, but are generally unstable due to evaporation or washout of the carrier solution. We propose applying a thin film of our unique, high flux polymer to both sides of a conventional FTM, which should dramatically increase the membrane's stability while providing minimal resistance to gas transport. Perfluoro-2-2-dimethyl-1-3 dioxole (PDD) copolymerized with tetrafluoroethylene (TFE) has CO2 flux rates of 30 times larger than other conventional membranes, such as silicone rubber and polysulfone, combined with a significantly lower water vapor to permeate gas ratio. These features will allow for excellent gas transport via facilitated transport, while minimizing the dehydration and resulting degradation of conventional FTMs, and the resulting system will have an estimated weight of just 4 pounds.

The most promising commercial applications for a lightweight CO2 removal system are use on manned space flights and planetary or orbital space stations, where both high selectivity and low system weights are desirable. As space missions achieve longer durations, the conventional system of LiOH absorption becomes even less practical. Additionally, stable FTM technology could be used in a number of industrial applications requiring high selectivity gas separations.

Dr. Stuart Nemser
Compact Membrane Systems Inc.
325 Hampton Road
Wilmington, DE 19803

Compact Membrane Systems Inc.
814 First State Blvd.
Wilmington, DE 19804