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Langmuir 1988,4,740-743
Adsorption of Neopentane by Nonporous Carbons and Silicas P.J. M. Carrott, R.A. Roberts, and K. S. W. Sing* Department of Chemistry, Brunel University, Uxbridge, Middlesex, UB8 3PH, U.K. Received January 14, 1988 The adsorption of neopentane (2,2-dimethylpropane)by a range of nonporous carbons and silicas has been studied. It is shown that the shape of the isotherm in the multilayer region depends only on the chemical nature of the adsorbent (i.e., silica or carbon) and is independent of the degree of hydroxylation or the degree of graphitization. This is shown by, inter alia, the constancy of the FHH index (2.19 f 0.03 for carbon and 1.99 f 0.03 for silica). Standard adsorption data for neopentane adsorbed on nonporous carbon and nonporous silica are presented and used to analyze the adsorption isotherms by the a,method.
Introduction The adsorption of neopentane has been studied on a number of nonmicroporous adsorbents including carbon~,'-~ and polymers?1' In the monolayer region of the isotherm it has been found that, provided the temperature of measurement is not too low, the neopentane molecule is freely rotating. At low temperatures (e.g.,
