1010.    ---------------.  [Synthesis of Paraffin From Carbon Monoxide and Hydrogen.]  Ber. Deut. Chem. Gesell., vol. 72B, 1939, p. 327-330; Chem. Abs., vol. 33, 1939, p. 3995.

        In the catalytic hydrogenation of CO with Co, Ni, or Fe catalysts at atmospheric pressure chiefly aliphatic hydrocarbons (benzine synthesis) are formed.  The working temperatures with Co and Ni are 180°-200° and with Fe 230°-250°.  With catalysts that are less favorable to the hydrogenation process, such as ZnO, Cr₂O₃, Mn₂O₃, reaction occurs only at higher temperatures (usually above 300°) and pressures (above 10 atm.), and O-containing compounds are formed, especially MeOH or synthol.  Aside from the nature of the catalyst, the temperature and pressure have a decisive influence on the course of the process.  With a Co catalyst a slightly increased pressure produces a remarkable change.  At 5-20 atm., solid paraffin is the chief product, and the yields of solid + liquid hydrocarbons and the life of the catalyst attain a maximum.  Any appreciable increase of pressure above these limits results in a rapid decrease in life of the catalyst.  At 50-100 atm. or higher O-containing compounds in increasing amounts with increasing pressures are formed, along with the paraffin hydrocarbons, and volatilization of the catalysts as Co carbonyl begins.  The use of Ni is restricted to pressures near atmospheric, for at slight overpressures the activity centers are broken down with formation of Ni carbonyl.  The new process, which gives solid paraffin as the chief product, is called the medium-pressure synthesis.  With a Co-ThO₂ kieselguhr catalyst (1:0.18:1) (abs. 984), the following yields were obtained at overpressures of 0, 1.5, 5, 15, 50, and 150 atm., respectively.  The yields are expressed in gm./m.³of so-called ideal gas (inert-free CO-H₂ mixture (1:2) at 0° and 700 mm.) employed, not that consumed, and represent the average yields during a 4-week run without renewal of the catalyst:  Total solid and liquid hydrocarbons, 117, 131, 150, 145, 138, 104; oil-free paraffin, 10, 15, 60, 70, 54, 27; oil boiling above 200°, 38, 43, 51, 36, 37, 34; benzine boiling below 200°, 69, 73, 39, 39, 47, 43; gaseous hydrocarbons including gasol, 38, 50, 33, 33, 21, 31.  The effect of pressure on the life of the catalyst is especially characteristic.  At atmospheric pressure the yield of total hydrocarbons fell from 120-130 gm. initially to 100 gm. within the 4-week period; at 1.5 atm. overpressure the yields were better; at 5 and 15 atm. overpressures, even after 1/2 yr. without regeneration of the catalyst, the yields were still 100-110 gm.; at 50 atm. overpressure they again fell more rapidly; at 150 atm. overpressure the activity of the catalyst decreased with extraordinary rapidity, and in the 2d week the yields fell below 100 gm.  The solid paraffin separates in a high degree of purity.  The oil-containing product softens at about 60° and melts clear at 90°-100°; after being freed from oil, it begins to melt about 80° and the last solid particle disappears at 100°-115°.  By stepwise extraction at the boiling point with different high-boiling solvents, fractions melting up to about 130° can be isolated.  The portion boiling above 300° of the total products obtained at 50-20 atm. overpressure contained 85.1-85.2% C and 14.7-14.9% H.  The crude liquid hydrocarbons are water-clear and are distributed uniformly through the boiling point range 30°-300°.  They are aliphatic and contain only a small amount of unsaturated compounds.  The total liquid products contained 84.6-84.8% C and 15.2-15.4% H.