369.     BROETZ, W.  [Systematics of the Fischer-Tropsch Catalysis.]  Ztschr. Elektrochem., vol. 53, 1949, pp. 301-306; Chem. Zentralb., 1950, I, p. 1432; Chem. Abs., vol. 44, 1950, p. 2358.

      Fundamental Fischer-Tropsch reaction:  CO+2H₂>CH₂+H₂O at atmospheric and at 5-20 atm. gage pressure between 160° and 186° is discussed.  On technical catalysts at pressures up to 10 atm. gage pressure the reaction rate is given by:  d[CO]:dt=k [H₂]²:[CO] where k at 7 atm. gage pressure varies from 7.8X10^-3 at 173° to 18.8X10^-3 at 186°, yielding an activation energy of 31 kcol. per mol.  At atmospheric pressure an activation energy of 28 kcol. per mol. is found.  At high pressures the reaction rate is:  d[CO]:dt=k₃ {H₂]: [CO]}{k₃[H₂]: (1+k₂[H₂])}.  The presence of CH₄ in the reaction mixture does not affect the rate or the nature of the products.  The catalysts gradually lose activity, which may be recovered by heating in H₂ at 400°.  The reaction takes place directly in 1 step at the catalyst surface without formation of an intermediate carbide.  The CH₂ radicals are combined at the catalyst surface under formation of double bonds at the chains ends, which are subsequently shifted by H exchange toward the center of the chains.