PATENT

3601. ----- [STEINKOHLEN-BERGWERK “RHEINPREUSSEN”].  [Production of Catalysts.].  German Patent Appl. St 58,750, PA 408,888, filed May 26, 1939.  FIAT Reel B-196, frames 841-847; PB 83252.

In producing catalysts in accordance with German Patent Appl. St 57,727 (abs. 3585), characterized by the use of unpurified solutions of Fe, Fe salts, or minerals for production of Fe  catalysts, and with German Patent Appl. St 57,988 (abs.. 3587), characterized by the addition of small amounts (0.005-0.5%) of Cu, Ag, or Au, only so much alkaline or ammoniacal precipitating agent is used to precipitate the catalyst from the solution of its salts as will establish at the end of the precipitation a pH concentration of 6.8-7.3.  Particularly suitable is a pH concentration indicated by the change of litmus to a pale violet.  The method as described removes 2 serious disadvantages of the former method:  The great expenditure of time and apparatus in completing the filtration and washing, and the difficulty in washing the precipitate to a relatively nonalkaline state.  The freedom from alkali is a preliminary condition for obtaining high activity and long life for the catalyst.