Over tungsten and rhodium fragmentation of the skeletal structure was also extensive but the production of methane was less dominant than with nickel. Reaction over nickel resulted in extensive production of methane with the formation of only relatively small amounts of products of higher carbon number. For straight-chained hydrocarbons there was a general trend for reactivity to fall with decreasing carbon number. The measurement of hydrogen liberated during hydrocarbon adsorption gave values for the mean hydrogen/carbon ratio for the adsorbed residues from ethane and propane in the range 0♴ to ca. Hydrocarbon adsorption, probably involving carbon-carbon bond rupture, was rapid and the coverage of the surface by hydrocarbon residues approached or exceeded 50%. With ethane, propane and neopentane the simultaneous adsorption of hydrocarbon and hydrogen has been measured at temperatures below but approaching the range used for hydrocracking. Activation energies and frequency factors have been obtained over nickel and tungsten. Rates have been measured for hydrocracking of the lower saturated aliphatic hydrocarbons in the presence of excess hydrogen over evaporated metal film catalysts of nickel, tungsten, rhodium and platinum and the distributions of products formed initially have been determined.
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