1018.    ---------------.  [Direct Synthesis of Petroleum Hydrocarbons at Ordinary Pressure.  I.  II.]  Ber. Deut. Chem. Gesell., vol. 59B, 1926, pp. 830-831, 832-836; Ges. Abhandl. Kenntnis Kohle, vol. 8, 1929, pp. 190-206; Chem. Abs., vol. 20, 1926, p. 2814.

       With metals of the 8^th group as catalysts, the catalytic hydrogenation of CO at ordinary pressure yields not CH₄ alone but a mixture of CH₄ with its homologs.  By following the reaction quantitatively, it was found that the first C derived from the CO is taken up by the catalyst, evidently with carbide formation, and from this carbide, present in the finest state of subdivision, the H₂ regenerates the metal and removes the C as hydrocarbons.  The carbides are apparently not the normal, low-C compounds stable at high temperatures but compounds rich in C and stable only at relatively low temperatures, and as a result, the C is removed from them not as CH₄ but as polymembered homologs of CH₄.  That in this process the hydrocarbons are not formed through HCHO or MeOH as in the high-pressure catalysis is confirmed by the fact that only hydrocarbons and never O-containing organic compounds are formed.  At temperatures such as are used in the high-pressure method, only CH₄ is formed.  Finely divided Co is an efficient catalyst, Fe is slower, and Ni is quite weak in the ability to produce hydrocarbons other than CH₄.  Better than the metals alone are mixtures of them (1-3 parts) with other substances (oxides of Cr, Zn, Be, the rare-earth metals, U, Si, Al, Mg, and Mn, active charcoal and amorphous C in other forms); faintly alkalinizing the Fe metal increases its catalytic activity.  The absence of toxic S compounds must be insured.  Commercial mixtures of CO and H₂ (especially water gas) may be used, S compounds being first removed by catalytic conversion into H₂S under conditions that will not change the composition of the gas as regards its other components; such a method of purification will be described elsewhere.  With all the gases used (water gas, mixtures poorer and richer in CO, moist CO, etc.), benzine was obtained if they had been sufficiently purified.  It is especially important to keep the temperature as low as possible (around 300° with Fe, 270° with Co, and 160° with Ni).  The higher the velocity of flow the more can the formation of CH₄ be suppressed but the poorer, of course, is the utilization of the gas mixture.  A part of the reaction product condenses in liquid form as soon as the reaction mixture cools, and the rest, remaining in the gas in vapor form, is recovered by the usual methods.  The condensed products are, depending on conditions, light oils like illuminating oil but also may contain higher boiling oils and deposit solid paraffin.  The benzines are H₂O clear with a pleasant odor, resembling Pennsylvania benzine, and contain only a few % of substances reacting with concentrated H₂SO₄, and do not change at all on standing.  The only other products besides hydrocarbons are CO₂ and H₂O.  In an experiment with an Fe-Co catalyst, about 100 gm. of liquid and easily liquefiable products were obtained per m.³ of water gas.