Temperature programmed desorption from LiAlO sub 2 treated with H sub 2
Temperature programmed desorption (TPD) measurements have been made of H{sub 2}O and H{sub 2} desorption from LiAlO{sup 2} treated at 923 K with He-H{sub 2} mixtures containing 990, 495, and 227 vppm H{sub 2}. Desorptions were into sweep gases of pure He and into He-H{sub 2} mixtures. The H{sub 2}O and H{sub 2} desorption peaks were shown to be the sums of first order subpeaks which had reproducible desorption activation energy and pre-exponential terms. For H{sub 2}O desorption, the activation energies were 96, 117, 134 kJ/mol (23, 28, and 32 kcal/mol). (Earlier work had identified an additional peak with an activation energy of 75 kJ/mol (18 kcal/mol).) Enhancement of desorption of H{sub 2}O by H{sub 2} in the sweep gas was confirmed. The enhancement results not from modifying the activation energies and pre-exponential terms for the various sites but from changes in the populations of sites participating in the desorption process so that sites with lower activation energies are increasingly involved. For those runs with He as the sweep gas, desorption of H{sub 2} could be observed. The subpeaks involved had activation energies within approximately 4 kJ/mol (1 kcal/mol) higher than the analogous peaks for H{sub 2}O desorption. 2 refs., 4 figs., 3 tabs.
- Research Organization:
- Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5020562
- Report Number(s):
- ANL/CP-74483; CONF-911111-5; ON: DE92001906
- Resource Relation:
- Conference: International conference on fusion reactor materials, Clearwater, FL (United States), 17-22 Nov 1991
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
BREEDING BLANKETS
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