3337.     TAYLOR, H. S., AND LIANG, S. C.  Heterogeneity of Catalyst Surfaces for Chemisorption.  I.  Zinc Oxide.  Jour. Am. Soc., vol. 69, 1947, pp. 1306-1312; Chem. Abs., vol. 41, 1947, p. 5772.

        New technique for determining adsorption isobars was applied to the study of the adsorption of H2 by ZnO over the temperature range 77-600 K.  It reveals desorption of chemisorbed H2 on raising the temperature through certain temperature ranges, followed by readsorption at still higher temperature. The data indicate a marked heterogeneity of the ZnO surface for the adsorption of H2 that must be taken into consideration in attempting to evaluate energies of activation for adsorption and catalysis.