3348.     ---------------.  [TECHNICAL OIL MISSION.]  Fischer-Tropsch Use of Iron Catalyst.  TOM Reel 26, bag 2463, document 9, frames 900,000,232-900,000,333 (particularly 286), Mar. 31, 1943.]

        X-ray investigations, made by Dr. Herbst and Dr. Halle on the Fe catalyst containing Cu, revealed that the Cu, besides aiding in the reduction of the catalyst, played another quite important role in the synthesis.  It was found in examining the standard catalyst that a new hexagonal carbide Fe₂C occurred, not yet described in the literature, which appeared to be necessary to the high activity of the catalyst.  This new hexagonal carbide, as Dr. Herbst discovered, becomes transformed in the course of time, particularly at the higher temperatures, into the carbide Fe₂C already identified by Hägg.  This transformation is retarded greatly by the addition of Cu so that it is regarded as a stabilizer in one of the intermediate states of the catalyst occurring during the synthesis.  For example, the addition of 2% Cu raises the conversion temperature about 50°.