826. ---------------.[EMMETT, P. H., AND BRUNAUER, S.] Use of Adsorption Isotherms for Measuring the Surface Areas of Catalysts and Other Finely Divided Materials. Trans. Electrochem. Soc., vol. 71, 1937, 12 pp. (preprint); Chem. Abs., vol. 31, 1937, p. 3371.

826. ---------------. [EMMETT, P. H., AND BRUNAUER, S.] Use of Adsorption Isotherms for Measuring the Surface Areas of Catalysts and Other Finely Divided Materials. Trans. Electrochem. Soc., vol. 71, 1937, 12 pp. (preprint); Chem. Abs., vol. 31, 1937, p. 3371.

Describes method for measuring the surface areas of catalysts, and of other finely divided substances, by using low-temperature adsorption isotherms of gases such as N₂, A, CO, O₂, and CO₂. Representative isotherms for 2 promoted Fe-synthetic-NH₃ catalysts, pumice, Ni on pumice, and NiO on pumice are presented. In the case of the Fe catalyst, it is shown that if the beginning of the linear portion of the isotherms is interpreted as the point of completion of a unimolecular layer, surface areas can be calculated that are approximately the same for all gases tried. Furthermore, the surface areas so calculated are large enough to accommodate the observed chemisorption of CO at –183° and the largest irreversible adsorption of H observed at –78°-100°. Only in the case of O at –183° is the volume taken up irreversibly by the catalyst several fold greater than a monomolecular layer. Presumably O reacts chemically with the outer layers of Fe atoms even at –183°. The method has so far been applied with apparent success to the catalysts and catalyst supports mentioned above and in addition, to 4 other synthetic NH₃ catalysts, 2 Cu catalysts, glaucosil, 2 soils and 2 soil colloids, samples of dry powdered bacteria, Cr oxide gel, and Cr oxide gel that had been glowed at 400°.