2751.     ---------------.  [PRING, J. N., AND FAIRLIE, D. M.]  Synthesis of Hydrocarbons at High Temperatures and High Pressures.  8th Internat. Cong. Appl. Chem., vol. 21, 1912, p. 65; Chem. Abs., vol. 6, 1912, p. 3363.

        Apparatus is a modified form of the pressure furnace used previously (abs. 2750).  The main reaction studied:  C+2H2=CH4.  Below 1,000 C and H2 at 1 atm. react so slowly, even in the presence of Pt as catalyst, that equilibrium values are not reached within any reasonably time.  H2 was brought into contact with a C rod heated to 1,100-1,600 by passing an electric current through it.  The containing walls of the Ni-steel reaction vessel (750 cc.) were H2O-cooled.  The CH4, yielded at any given temperature of the C rod, corresponded to the equilibrium value for this temperature since CH4 does not decompose in the colder regions of the apparatus.  Furthermore, the amount of C2H4 formed as a by-product at temperature below 1,500 is so slight that the reaction C2H4+2H2=2CH4, which takes place in the cooler parts does not appreciably affect results.  C2H2 first becomes noticeable (0.001%) at 1,650.  Various grades of C and graphite were tried.  The Sodeau apparatus was used in analyzing the products.  Amorphous C gave higher % CH4 than graphite.  Upon long heating of the former the values dropped owing to the gradual change into graphite.  Partly purified amorphous C heated 3 hr. at 1,275, H2 at 100 atm., gave equilibrium values:  21.5% CH4, 0.25% CO, and 0.002% C2H4.  Pt-coated amorphous C, preliminarily purified in Cl2, after 2.5 hr. at 1,100, 20 atm., gave 6.35% CH4 and 1.1% CO.  Acheson graphite, 1,200, 2.5 hr., 105 atm., 17.5% CH4 and no CO.  Other graphites, 1.6-4.7% CH4.  At 1,200-1,300 and at 30-50 atm., equilibrium is reached in about 2 hr.; above 1,400, in about 15 min.  The reaction velocity at 200 atm. exceeds by far that at 1 atm.  The results are in agreement with the mass action law.  At 1 atm. the equilibrium value of CH4, in presence of graphite, is 0.25% at 1,200 and 0.07% at 1,500.  With amorphous metastable C the values are 0.36% at 1,200 and 0.18% at 1,500.  At n atm., the CH4 pressure is n times that at 1 atm.  From the data obtained, the authors calculate approximately the heat of reaction for changing amorphous C into graphite, to be 1,480 cal. at 1,200; 1,950 at 1,300; 2,450 at 1,400; and 3,200 at 1,550.  It follows that the mean specific heat of amorphous C above 1,100 is higher than that of graphite, and that difference increased rapidly with the temperature.  No saturated hydrocarbon other than CH4 was produced in any of the experiments.