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Title: A mechanistic study of molecular sieving inorganic membranes for gas separations. Final report, [August 1, 1992--July 31, 1993]

The permeability of gases with kinetic diameters of 2.89 {Angstrom} to 3.9 {Angstrom} were measured through microporous silica hollow fiber membranes at 298 K to 473 K at 20 atm feed gas pressure. Permeabilities ranged from 0.01 Barrer to 1000 Barrer and were inversely proportional to the kinetic diameter of the penetrant. Linear Arrhenius plots were obtained from permeability data activation energies ranged from 7.5 to 13.5 kcal/mole. The activation energies for the hollow Tiber membranes were consistent with literature data for diffusion of hydrocarbons in zeolites. High separation factors were obtained for O{sub 2}/N{sub 2} and CO{sub 2}/CH{sub 2} mixtures. The mixture separation factors for O{sub 2}/N{sub 2} decreased from 11.5 at 298 K to 4.6 at 423 K. Over the same temperature range, CO{sub 2}/CH{sub 2} separation factors decreased from 186 to 22.3. Separation factors for O{sub 2}/N{sub 2} mixtures were up to 20% larger than the values obtained from pure gas measurements below 373 K. A similar effect was seen for CO{sub 2}/CH{sub 2} mixtures after the membrane had been heated to at least 398 K and then cooled in inert gas flow. Differences between separation factors and ideal gas values is attributed to a competitive adsorptionmore » effect where the more strongly interacting gases (O{sub 2}, CO{sub 2}) saturate the surface and block the transport of weakly interacting gases (N{sub 2}, CH{sub 4}).« less
Authors:
Publication Date:
OSTI Identifier:
10118702
Report Number(s):
DOE/ER/14290--1
ON: DE94005972; BR: KC0302020
DOE Contract Number:
FG06-92ER14290
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 3 May 1993
Research Org:
Colorado School of Mines, Golden, CO (United States). Dept. of Chemical Engineering and Petroleum Refining
Sponsoring Org:
USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; POROUS MATERIALS; PERMEABILITY; ZEOLITES; SILICA; GASES; DIFFUSION; SEPARATION PROCESSES; PROGRESS REPORT; MEMBRANES; MOLECULAR SIEVES; OXYGEN; NITROGEN; METHANE; CARBON DIOXIDE 400105; SEPARATION PROCEDURES