Effect of oxidation on the surface heterogeneity of some graphitized carbons

✍ Scribed by D.W.L Griffiths; W.J Thomas; P.L Walker Jr.

• Publisher: Elsevier Science
• Year: 1964
• Tongue: English
• Weight: 860 KB
• Volume: 1
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(64)90014-4

✦ Synopsis

fraction of the surface of some graphitized carbons are energetically heterogeneous. That part of the surface which is heterogeneous has sites for which N, shows a higher isosteric heat of adsorption at 78°K than the uniform portion constituting the major fraction of surface and for which the heat of adsorption is constant. The effect of oxidation on this surface heterogeneity has been studied for three different graphitized carbons: Graphon, GP33, and British Pile Grade A Graphite. It was found for the Graphon and GP33 that the proportion of sites which offered high heats of adsorption to N, increased sharply with an increasing amount of 0, burn-off. Although the unoxidized Pile Grade A Graphite was less homogeneous than either Graphon or GP33, burn-off did not produce such a marked increase in the fraction of heterogeneity. The effects which these changes in surface heterogeneitv have on the isosteric heats of adsorption and integral molal entropy .~ of adsorption are discus&d.