3338. ---------------. [TAYLOR, H. S., AND LIANG, S. C.] Heterogeneity of Catalyst Surfaces for Chemisorption. II. Zinc Oxide-Chromic Oxide, Manganous Oxide-Chromic Oxide, Chromic Oxide Gel. Jour. Am. Soc., vol. 69, 1947, pp. 2989-2991; Chem. Abs., vol. 42, 1948, p. 1793.
As described in the previous paper in this series, the techniques of measuring chemisorption with increasing and decreasing temperatures at constant pressure were applied to a study of ZnO-Cr2O3 catalysts and Cr2O3 gel. These substances reveal heterogeneity of surface. MnO-Cr2O3 catalysts do not show desorption-readsorption phenomena on raising the temperature. The isobar on decreasing temperature consequently was horizontal over a considerable temperature range. The surface, nevertheless, exhibits a partial heterogeneity. The criterion of “pumping-off at temperature” was shown to be doubtful in distinguishing van der Waals’ and chemisorption of H2 in certain temperature ranges with these catalysts.