Vacuum sorption pumping at cryogenic temperatures of argon and oxygen on molecular sieves

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6969270

Perona, J J; Gibson, M R; Byers, C H

Cryosorption pumping is a method of excavating enclosed volumes by adsorbing gas on a deep bed of solid sorbent (typically a zeolite) at cryogenic temperatures. Modeling the dynamic behavior of these systems for air pumping requires information on two major constituents of air, oxygen and argon, which had not been previously studied, as well as data on a nonadsorbing specie, helium. Deep beds of Davison 4A molecular sieves were subjected to a metered flow of pure gas and the pressure history of the experiment was monitored, using computer data acquisition techniques. Particle size variations is the major variable in determining the mechanism of the process. The data acquired in the current study compare favorably with previous experiments. Previously developed models for the dynamic sorption behavior of deep beds under vacuum for two extreme conditions, micropore and micropore control were tested in this study. The sorption behavior of argon clearly fit into the category of macropore controlled sorption, indicating that these species are adsorbed primarily on the surface of the zeolite crystals, much like the theoretical and experimental results for N/sub 2/ cryosorption on the same sieves of Crabb. On the other hand oxygen sorption is most likely micropore controlled, and may be molded by the method of Praznick. 11 refs., 7 figs., 1 tab.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6969270
• Report Number(s): CONF-880779-1; ON: DE88013840
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420200 -- Engineering-- Facilities
Equipment
& Techniques
640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
ADSORBENTS
AIR
ARGON
BOUNDARY CONDITIONS
CRYOPUMPS
DATA ACQUISITION
ELEMENTS
EQUIPMENT
FLUIDS
GASES
HELIUM
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
LABORATORY EQUIPMENT
MATERIALS
MINERALS
MOLECULAR SIEVES
NONMETALS
OXYGEN
PRESSURE DEPENDENCE
PUMPING
PUMPS
RARE GASES
VACUUM PUMPS
ZEOLITES