1705. ------. [INTERNATIONAL HYDROCARBON SYNTHESIS CO.] [Regeneration of Thorium Catalysts.] French Patent 856,933, Aug. 16, 1940; appl. filed June 27, 1939. Chem. Zentralb., 1941, I, p. 3036.

The catalyst used in the hydrogenation of CO, included with other constituents such as Ni or Co, can be dissolved in H₂SO₄ and precipated at 60° -70° with an alkaline carbonate solution. The precipitate is essentially Th, and the other constituents remain in solution. The precipitate is dissolved in H₂SO₄ and a solution of K₂SO₄ or a mixture of K₂SO₄ and Na₂SO₄ or KCl and Na₂SO₄ or KCl and H₂SO₄ is added. The precipitated double salt of Th-K-sulfate will be separated from the solution and changed into insoluble Th carbonate, which results through heating with a concentrated solution of alkali or ammonium carbonate. One uses an excess of carbonate and heats the solution to 90° to precipiate the Fe present in the form of colloidal hydroxide which is filtered off. The Th carbonate is precipitated with H₂SO₄ or HCl. This is washed with warm H₂O and dissolved in 60% HNO₃. This solution is then ready for the production of fresh catalyst.