Gas separation properties of phosphazene polymer membranes

Conference · Sat Oct 01 04:00:00 EDT 1988 · Sep. Sci. Technol.; (United States)

OSTI ID:6223068

McCaffrey, R R; Cummings, D G

In this paper the gas separation properties of poly(bis(phenoxy)phosphazene) are reported. Transport behavior was determined by time-lag techniques and correlated with membrane microstructural studies. Test gases were run as pure or single-species gases, which included atmospheric gases, hydrocarbons, sulfur dioxide, and hydrogen sulfide. Transport of atmospheric and hydrocarbon gases was found to be a diffusion controlled process; i.e., correlated with molecular size. Transport of CO/sub 2/, H/sub 2/S, and SO/sub 2/ was found to be a sorption controlled process since high solubilities were measured and transport deviated from the diffusion controlled permeability-size correlation. Membranes were prepared using spin and knife casting techniques. Solvent evaporation rate during the casting process was used to provide membrane microstructures. Rapid evaporation by spin casting resulted in dense homogeneous films, with permeabilities ranging from 2-6 barrers for the slowest (Ar) to the fastest gases (He). Slow evaporation by knife casting (minutes-hours) resulted in a more open polymer structure. Two enhancement effects were observed in the transport behavior of the knife-cast membrane: (1) an overall increase in permeability for all gases depicting the more open membrane structure (ranged from 4-76 barrers for all gases) and (2) an enhancement of the selectivity of gases which exhibited strong solubility effects. Sulfur dioxide and hydrogen sulfide exhibited the greatest selectivity enhancement. The pure gas solubility selectivities for SO/sub 2/ and H/sub 2/S with respect to the atmospheric and hydrocarbon gases were found to be approximately 1000 and 200 respectively.

• Research Organization: Idaho National Engineering Laboratory, ID (USA)
• OSTI ID: 6223068
• Report Number(s): CONF-871038-
• Conference Information: Journal Name: Sep. Sci. Technol.; (United States) Journal Volume: 23:12,13
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400105* -- Separation Procedures
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
DATA
DIFFUSION
EFFICIENCY
EXPERIMENTAL DATA
FLUIDS
GASES
HYDROGEN COMPOUNDS
HYDROGEN SULFIDES
INFORMATION
MASS TRANSFER
MEMBRANES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXIDES
OXYGEN COMPOUNDS
POLYMERS
SEPARATION PROCESSES
SORPTION
SULFIDES
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES