1908. -----. [KÖLBEL, H., AND ACKERMANN, P.] (Steinkohlen-Bergwerk "Rheinpreussen"). [Synthetic Gasoline.] German Patent 743,569, no date. Kainer, p. 266.

With use of a catalyst containing at least 99.5% Fe, the synthesis is so conducted that mainly unsaturated C₂-C₄ hydrocarbons are produced, and then these are polymerized to high-grade antiknock gasoline.