PATENTS

3108.----- [RUHRCHEMIE, A. G.]  [Process for the Catalytic Cracking of the Hydrogenation Products of Carbon Monoxide to Olefinic, Low-Boiling Hydrocarbons.]  German patten Appl. --, R 720, filed July 20, 1944.  FIAT Reel K-30, frames 7,782-7,790; PB 73,587; TOM Reel 37, bag 3,451, item 36, 7 pp.; Meyer Transl. PC-S-II, Fischer-Tropsch, vol. 5, ch.149, 1949, p. 13.

In the catalytic cracking of synthetic hydrocarbons to olefins, especially those which are capable of being  polymerized to high antiknock gasolines, the cracking takes place at 500°-520° at catalyst loads up to 20 cc. of added product per 100 cc. of catalyst per hr. ( preferably 10 cc. ) in presence of such quantities of steam that the partial pressure of the added hydrocarbons amounts to about 10-20% of the total pressure.  The catalysts used have been precipitated with NH₃ at about 50° from a mixture of silicic acid solution and alkali reaction until the alkali salts have been thoroughly removed, dried, and heated to about 500°.  The SiO₂ content lies 30-50%, preferably 33-40%.  Example:  690 cc. of water glass solution are diluted with 12 l. of H₂O and 390 cc. HNO₃ (1:1) added with stirring.  A clear silicic acid solution is formed.  3,000 gm.  (Al (NO₃)₃).  9 H₂O are dissolved in 4 l. of H₂O and the clear solution is mixed with the silicic acid solution.  The mixture is warmed to about 50°.  2,000 cc. of a concentrated solution of NH₃ is added to this mixture with stirring .  The precipitation temperature rises to about 55°.  The resulting precipitate is removed and washed several times with H₂O, while maintaining an alkaline medium, until the salt is thoroughly removed, dried, shaped, and heated to 500°.  The finished catalyst has an alkali content < 0.2% 12 cc. per hr. of a diesel oil fraction from the Fischer-Tropsch synthesis b. 200°-350° and 12 cc. of H₂O are passed over 100 cc. of this catalyst at 500°.  The yield is 11% by weight of a gasoline b. 50°-200° and 31% by weight of C₃-C₅ Olefins from which by polymerization 27.9% by weight of polymer gasoline can be obtained.  Together with the 2.1% by weight of C₅ paraffins obtained from cracking and the 0.6% by weight of C₅ olefins not touched by the polymerization, there are obtained altogether 41.6% by weight of gasoline b. up to 200° and having an octane number of 81.