1702. ------. [INTERNATIONAL HYDROCARBON SYNTHESIS CO.] [Regeneration of Exhausted Cobalt Catalysts.] Norwegian Patent 62,414, April 29, 1940; appl. filed Sept. 16, 1938. Chem. Zentralb., 1940, II, p. 1973.

Exhausted Co catalysts from the synthesis of hydrocarbons from CO and H₂ are regenerated by dissolving in HNO₃ and reprecipitating the dissolved constituents. Separation of the salts from the undissolved kieselguhr is accomplished satisfactorily if dilute HNO₃ of 20% concentration, preferably 3-5%, is used. The treatment with HNO₃ is performed at 70° -90° when only moderate stirring is needed. The paraffin deposited on the catalyst melts, is removed with the solution, and separates on cooling. By this method an HNO₃ already containing Co salts can be used and then a concentrated Co(NO₃)₂ solution is directly obtained.