Project Title:

Zeolite-Polyphosphazene Membranes For Air Revitalization in Life Support Systems

94-1	12.02	2514		

Zeolite-Polyphosphazene Membranes For Air Revitalization in Life 
Support Systems

Abstract:

A new ceramic supported zeolite-polyphosphazene membrane will be 
developed for air revitalization in life support systems. A 20% 
potassium exchanged zeolite A with a pore diameter around 3.3 A has 
proven to be suitable for separation of H2 (2.89 A) and C02 (3.3 A) 
from N2 (3.64 A), O2 (3.46 A) and CH4 (3.8 A). However, selective 
adsorption on granular zeolites is a non-continuous process. In 
addition, potassium zeolite A has special affinity to H20. 
Therefore, a desiccant bed is needed before a C02 absorbent bed in 
the current separation process. The proposed composite membranes 
have a thin film of hydrophobic polyphosphazene coated on zeolite 
particles to prevent them from coming in contact with H20. 
Therefore, this new membrane separation system can effectively 
separate C02 from cabin air or separate unreacted H2 and C02 from 
Bosch reactor exhaust gas mixtures in the life support systems of 
space stations. This continuous separation process has several 
advantages over alternative processes, including ease of operation, 
low maintenance, cost, volume, weight and energy consumption. Phase 
I work will consist of various experiments to demonstrate the 
technical and economic feasibility of the proposed technology. The 
deposition process as well as the selectivity in desired gas 
mixture separations of new ceramic supported zeolite-
polyphosphazene membranes will be investigated in detail. The 
technology developed in Phase I will provide a technical foundation 
for the Phase II scale-up process. Pilot tests in Phase II will be 
designed to allow for the future commercial production and 
application.

Separation properties of the proposed zeolite-polyphosphazene 
membranes can be tailored easily to specific applications. 
Therefore, the potential of these composite membranes in commercial 
gas and liquid separations are enormous. In addition to the air 
revitalization of closed environmental systems such as submarines 
and spacecraft, this separation system can be applied to hydrogen 
recovery from petroleum refining, removal of carbon dioxide from 
natural gas, olefin and paraffin separations, etc. All these 
applications are of strong commercial and petrochemical interest. 
The many economic advantages of the proposed technology will allow 
them to penetrate the market segments discussed above at an 
accelerated pace.

Key Words

Applied Material Technology, 
12 Quail Dr. 
Weaverville, NC 28787