388.     ------.  [BRUNAUER, S., AND EMMETT, P. H.]  Chemisorptions of Gases on Iron-Synthetic-Ammonia Catalysts.  Jour. Am. Chem. Soc., vol. 62, 1940, pp. 1732-1746; Chem. Abs., vol. 34, 1940, p. 6156.

      Chemisorption experiments were performed on the following Fe-synthetic-NH₃ catalysts; unpromoted catalyst containing 0.15% Al₂O₃, singly promoted catalyst containing 10.2% Al₂O₃, doubly promoted catalyst containing 1.59% K₂O and 1.3 Al₂O₃, catalyst containing 1.07% K₂O, singly promoted catalyst containing 1.03% Al₂O₃ and 0.19 ZrO₂, and doubly promoted catalyst containing 0.35% Al₂O₃ and 0.08 K₂O.  The weights and reduction schedule (time and temperature) are given for the preparation of these catalysts.  The chemisorptions of O₂ and CO at –183° and –78°, CO₂ at –78 and 0°, N₂ at 400°-450°, H₂ at –78° (type A) and H₂ at 100° (type B) were studied on these catalysts.  From the investigation of these adsorptions individually and from their mutual inhibitory effects the following conclusions are drawn:  The CO₂ chemisorption is located on the surface alkali molecules, and the 5 other chemisorptions on the surface of Fe atoms.  CO and CO₂ are chemisorbed as molecules, N and H as atoms, O probably as ions.  Both the Al₂O₃ and K₂O promoters are strongly concentrated on the surfaces of singly and doubly promoted catalysts.  The alkali promoter is very intimately mixed with Fe atoms on the surface.  The Fe surface is heterogenous; the heterogeneity probably is due to differently developed crystal faces.  The molecular CO and CO₂ chemisorptions are purely surface adsorptions; O ions penetrate several layers below the surface; N and H atoms probably do not penetrate below the surface but migrate to Fe atoms located under surface promoter molecules.  Both the K₂O and Al₂O₃ promoters give evidences of specific chemical effects.