1836. KOCH, H., AND TITZENTHALER, E. [Determination of the Degree of Branching in Synthetic and Natural Solid Paraffins With the Help of Hydrogenating Decomposition on a Cobalt Catalyst.] Brennstoff-Chem., vol. 31, 1950, pp. 212-221; Chem. Abs., vol. 44, 1950, p. 9335.

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Literature Abstracts

Various synthetic and natural solid paraffins were decomposed by hydrogenation on a Fischer-Tropsch Co catalyst within the temperature range 180°-230°. The liquid hydrocarbons obtained with the main product CH₄ were analyzed in the boiling range 30°-170° by close fractionation. Since by demethylation splitting, branching is preferably maintained in the same positions, quantitative conclusions can be drawn from the amount of isocompounds in the decomposition product as to the original isocontent of the initial paraffin. Taking a straight-chain paraffin, n-octadecane, for example, it can be shown that even with careful decomposition a limited amount (about 4%) of branched hydrocarbons formed through isomerization must be reckoned with. A synthetic gatch fraction obtained on a Co or Fe catalyst yielded about 30% of isoparaffin, while a synthetic hard paraffin gave an average proportion of branched compounds of 38%. A soft paraffin from the spindle-oil fraction of an Emsland crude oil yielded 8% and a hard paraffin separated from the machine oil fraction 25% of isocompounds. A Tief-Temperature Hydrierung brown-coal paraffin showed about 11% of branched hydrocarbons. The hydrogenating decomposition also was accompanied to a limited extent by aromatization whereby the methylated aromatics appeared to a large extent as benzol. Tests on the splitting hydrogenation of paraffin on active Fe catalysts did not produce the desired results at the temperatures employed up to 350°. It was further discovered that Co catalysts temporarily lose their ability to split hydrocarbons by hydrogenation when small amounts of NH₃ are added to the H₂.