The adsorption of helium by carbonaceous solids

• Published in: Carbon (New York) 1963-10, Vol.1 (1), p.17-24
• Main Authors: Kini, K.A, Stacy, W.O
• Format: Article
• Language: English
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/0008-6223(63)90005-8

The adsorption of helium by graphite, active carbon, carbon black, cokes, coals, and other carbonaceous solids has been studied at temperatures from 77 to 560°K. Adsorption at 298°K depends markedly on the nature of the material, and in general increases with increasing internal surface area and increasing true density. At low temperatures some carbons, such as brown coal char and carbon black, adsorb strongly; others, such as certain vitrains and low-temperature coke, adsorb weakly at all temperatures studied, and may even show an apparent negative adsorption below 200°K. The latter effect is attributed to closure of the pores by thermal contraction. The isosteric heats of adsorption on active carbon increase from about 0.6 kcal/mole at 85°K to about 3 kcal/mole at 400°K. Following the theory of De Boer and Kruyer (1), it is suggested that the electrical conductivity of the carbon has an important influence on its adsorptive capacity for helium. The accuracy of determination of the true density of high-density carbons by helium displacement at room temperature can be seriously affected by adsorption of the helium.