1145.    -------------.  [GARNER, W. E., AND KINGMAN, F. E. T.] Heat of Adsorption of Hydrogen and Carbon Monoxide on Zinc and Chromium Oxide Catalysts.  Trans. Faraday Soc. vol. 27, 1931, pp. 322-333; Chem. Abs., vol. 25, 1931, p. 4758.

       Heats of adsorption and adsorptive capacity of H₂ and CO on ZnO, Cr₂O₃, and ZnO-Cr₂O₃ catalysts were measured by means of a vacuum calorimeter previously described.  The heats of adsorption ranged from 25-10 cal. per gm. mol., the maximum value being obtained for the first small quantities adsorbed.  The heat of adsorption of CO on ZnO is the same as that of ZnO-Cr₂O₃, although the adsorptive capacity is much greater in the latter case.  This indicates that the greater efficiency of the mixed catalyst is due to an enlargement of the internal area of the catalyst.  Cr₂O₃ and ZnO did not adsorb H₂ strongly as the mixed catalyst, but the Cr₂O₃ adsorbed CO very readily.  At low temperatures H₂ and CO are mainly adsorbed without disruption of the molecules, but at 100° and over the adsorption was irreversible, and the gas could only be removed as water and CO₂, respectively, by heating to high temperatures.  In the case of the mixed catalyst, the rate of evolution from 1 type of adsorbed film was greater than the rate of condensation to a second type of film, so that on heating to about 100° of a catalyst that had adsorbed H₂ at 20°, there occurred an evolution of H₂ which was followed by slow readsorption.