Use of Krypton for Surface Area Measurements

Abstract

WE have recently discussed1 some criteria for the applicability of various gases in measuring the surface areas of solids by the Brunauer–Emmett–Teller2 method. We concluded that the use of krypton in this technique led to valid and useful results and that previous criticism of the use of this gas was unfounded. However, Thomas3 has again suggested that ‘anomalous’ Brunauer–Emmett–Teller plots obtained from krypton adsorption measurements render the use of this gas undesirable. He proposes that the occurrence of phase-changes in the adsorbed film, evidenced by discontinuities in the adsorption isotherm, are associated with these ‘anomalous’ (and presumably suspect) results.