Chemisorption of halogen on carbon—II Thermal reversibility of Cl2, HCl and H2 chemisorption

✍ Scribed by Haim Tobias; Abraham Soffer

• Book ID: 103002185
• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 733 KB
• Volume: 23
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(85)90114-9

✦ Synopsis

There are surface double bonds on carbons which differ from the graphitic surface n-bonds in their chemical reactivity. They may be created by degassing prechlorinated or prehydrogenated carbon samples, besides their natural occurrence in nontreated carbons.

Cl?, H, and HCI may be added to these double bonds and partially dcgassed by thermal cycling in presence of the gases. This indicates that at least part of these olefinic bonds are thermally labile and are, therefore, important for catalysis and surface chemical modifications of carbons. The surface concentration of the labile bonds is low, amounting to a few hundredths of meqi 100 m' of carbon surface area. discrimination between physiso~tion and chemiso~tion of HI on carbon can be made by analysis of the dependence of adsorption on temperature. With Cl?. considerable overlap between the two processes takes place.