Kinetics of the graphite-oxygen reaction near 1000°K

✍ Scribed by R.J. Tyler; H.J. Wouterlood; M.F.R. Mulcahy

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 1013 KB
• Volume: 14
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(76)90130-5

✦ Synopsis

T'he kinetics of oxidation of spectroscopic grade ~lycrystall~ne graphite have been studied by a flow method which allowed the partial pressure of oxygen &,I to be changed abruptly during the coursd of the reaction. The changes were made in two alternative ways: by changing the total pressure of an oxygen/nitrogen mixture of constant composition or by changing the composition at constant total pressure. After the effect of diffusion resistance on the rate had been shown to be negligible and the effects of self-heating, burn-off and traces of gaseous impurities allowed for, the order of reaction (E in the empirical expression: rate = p$) was found to vary from 0.34 (at 993°K and mean ps = 16 torrt) to 0.19 (at 963°K and mean po2 = 24.5 torr). In certain circumstances, the response of the rate to changes in ps is subject to a "memory" effect. This is attributed to fast, diffusion-controlled chemiso~tion of a minute amount of hydrogenous impurity on part of the active surface of the graphite.