1302. HAENSEL, V. Kaiser Wilhelm Institut für Kohlenforschung, Mülheim. CIOS Rept. XXV-1, 1945, 16 pp.; PB 284; TOM Rept. 9; TOM Reel 197; TAC Rept. SnMC-3.

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Literature Abstracts

Contains information obtained in interviews with Drs. Pichler and Koch. The subject matter on Ru catalyst, medium pressure catalysts, synthesis with Fe catalysts, isosynthesis, and aromatization has already been reported in abs. 1303, and 701. The magnetic-chemical investigation of the Fe catalyst showed that higher carbides, such as Fe₂C, can be formed during the synthesis at 220°, but that they decompose between 300°-400°, leaving Fe₃C as the only stable component. It was found that the most active catalysts were those containing the most Fe₃C. When the catalyst is pretreated at about 1/10 atm. absolute pressure, more Fe₃C is obtained than at atmospheric pressure. During the synthesis, the amount of Fe₃C decreases at the catalyst deteriorates, while the concentration of Fe₃O₄ increases. When an equilibrium mixture of Fe₃C and Fe₃O₄ appears to exist in the catalyst, there is no rapid drop in activity, but with a higher concentration of Fe₃C an initial decrease in activity is observed. An attempt was made to prepare the Fe₂C by reducing Fe oxide with H₂ and then passing CO over it and measuring the CO₂ formed. Then H₂ again was passed over the catalyst at higher temperatures, and the amount of CH₄ was determined. From the data it was concluded that Fe₂C was formed. However, magnetic measurements showed that Fe₃C also was present, thus indicating that, along with Fe₂C and Fe₃C, a third carbide must be present richer in C than Fe₂C. In other words, the Fe₃C crystallites must be embedded in a phase with C:Fe ratio exceeding 2:1. Additional Curie points were observed but not identified. At higher temperatures, Fe₃C becomes sintered, and care must be taken to maintain the temperature low enough to prevent it. Formation of Fe₃C does not occur if the fresh untreated catalyst is impregnated with water gas under pressure at 220°. Some Fe₃C can be obtained at 280° under such conditions, but the catalyst produced is not good.