694.    DENT, F. J., BLACKBURN, W. H., MILLETT, H. C., AND MOIGNARD, L. S.  Investigations of the Use of Oxygen and High Pressure in Gasification.  IV>  Synthesis of Gaseous Hydrocarbons at High Pressure.  Rept. 50, Joint Research Committee, Institution of Gas Engineers and University of Leeds; Inst. Gas Eng. Commun. and Repts., Commun. 26, 1946, 52 pp.; Gas World, vol. 125, 1946, pp. 680-682; Chem. Abs., vol. 41, 1947, p. 3277.

      In the light of the knowledge gained in the laboratory, consideration is given to 4 processes:  (1) The Lurgi process for complete gasification; (2) a 2-stage process for complete gasification involving the production of gaseous hydrocarbons by hydrogenation; (3) a process of gasification at high pressure combined with CH₄ formation by catalytic synthesis; and (4) a process of carbonization in which internal heating is obtained by the exothermic hydrogenation and decomposition of the coal.  It is doubtful whether the Lurgi process would produce, from British coals, a gas with as high a heating value as that normally supplied, and it would probably require some pretreatment of the fuels to render them noncaking.  When complete gasification is required the 2d process is more suitable for bituminous coals.  A detailed analysis of the mechanism by which gaseous hydrocarbons are produced indicates that, in this process also, the yield of enriching hydrocarbons would be limited.  It appears that gas of approximately 500 B.t.u./cu. ft. might be readily obtained by synthesis without the need of additional gaseous hydrocarbons from hydrogenation.  The solid residue from the hydrogenation of coal is particularly combustible; although in the laboratory it had not been obtained as yet in large strong pieces.  Coals were hydrogenated in a vessel of 6 3/8 in. internal diameter, which was not externally heated.  All coals except anthracite fused under high pressure; and, unless they were first rendered noncaking, difficulty was encountered in securing uniform gas flow and reaction throughout the charge.  Coals that were not pretreated could be hydrogenated if the sizes below 1/8 in. were separated and charged down the side of the vessel.  With such a graded charge it was possible to treat satisfactorily a wide range of coals, including semianthracites, caking coals, and high-volatile, weakly caking coals.  When coals were heated under controlled temperature conditions and under pressure in a 1-in.-diameter reaction tube the gas arising from the decomposition of the fuel was high in hydrocarbons, even when the atmosphere supplied was rich in hydrocarbons.  At 50 atm. and 800°, gas containing 30% CH₄ was prepared from C and H₂ at space velocities as high as 20,000 with Ni supported on porous pot as the catalyst.  CH₄ was decomposed rapidly and almost completely at a high temperature, high pressure, with excess steam, and in the presence of a Ni catalyst.