333.    BRAUDE, G., AND BRUNS, B.  [Kinetics and Mechanism of the Catalytic Hydrogenation of Carbon Monoxide.  II.  Formation of Iron Carbide During Hydrogenation of Carbon Monoxide on an Iron Catalyst.]  Jour. Phys. Chem. (U.S.S.R.), vol. 22, 1948, pp. 487-494; Chem. Abs., vol. 42, 1948, pp. 7147-7148. 

                  Mixtures of CO and H₂ in the ratios 1:3 to 1:5 were circulated at 225°-350° over an Fe catalyst prepared by H₂ reduction of Fe₃O₄.  The main reaction occurring was nFe+CO+H₂→Fe_nC+H₂O (I).  This was proved by the following observations:  (a) The gas pressure dropped first (for example, for 5 min.) rapidly and then very slowly.  The rapid drop (after cooling the reaction product) corresponded to twice the original amount of CO.  (b) The reaction product was mainly H₂O, and the amount of CH₄ and CO₂ formed was too small to account for the CO consumed.  (c) The missing C was found in the catalyst.  When the catalyst was used for longer time, the concentration of C in it increased and its efficiency decreased; the catalytic activity almost disappeared when 0.24 atom C was deposited/atom Fe.  The slow drop of pressure was due to the reaction between this carbide and the excess of H₂.  The rate of reaction I increased 2.5 times when the initial pressure of CO was raised from 20 to 241 mm. dibutyl phthalate and was about proportional to the square root of the H₂ pressure (46-1.103 mm. dibutyl phthalate).  The energy of activation (from the temperature coefficient) of reaction I was 15,500 cal./mol.  The formation of CH₄ is due to the reaction nFe+2CO→Fe_nC+CO₂.  This reaction was studied in the absence of H₂.  It follows the equation of the first order, is slower than I, and has an apparent energy of activation (264°-350°) of 6,900 cal./mol.  The mechanism of the hydrogenation of CO is discussed. 

                  BRAUDE, G. E.  See abs. 1591, 1592.