3699.     WILKINS, E. T., AND JOLLEY, L. J.  Catalytic Production of Methane.  Coke and Gas, vol. 9, 1947, p. 245.

        Paper presented at the 11^th International Congress of Pure and Applied Chemistry, London, July 1947.  The work of the British Fuel Research Station is reviewed.  The process has reached such a perfected stage that no obstacle appears to stand in the way of building a full-scale plant whenever desired.  The cost of synthetic CH₄ production is made up largely of the cost of making the necessary water gas.  Catalysts of Ni, ThO₂, MgO, all supported on kieselguhr, have been used to promote the reaction.  4 primary difficulties have been met.  (1) C deposition on the catalyst.  Methods for prevention are:  To add steam to the reaction gases; to increase the H₂:CO ratio of the gases; to select a catalyst least susceptible to C deposition; and to study the correct design of the reaction vessel.  (2) Sintering of the catalyst.  This can be avoided by keeping the actual temperature of the catalyst below 600° C.  The actual temperature is found to be about 150° below that of the temperature as measured.  (3) Poisoning by S.  This is the greatest single cause of catalyst deterioration and occurs when the Ni has absorbed a 2-3% of S by weight.  It can be avoided by using a gas of extreme purity, but it is preferred to use a cheaper method of using a gas of moderate purity (below 0.03 grain S per 100 cu. ft.) and secure a moderate catalyst life of 3 months.  The above purity is secured by use of the well-known Fe₂O₃·Na₂CO₃ mixture at 200°.  (4) Dissipation of the heat of reaction.  This is secured by watercooling the shell of the reaction vessel to 200°.  The catalyst is arranged to line the wall of the vertical tube, the outside of which is water cooled.