THE author has studied the hydrogenation reactions in connection with the transformation of tar and asphaltic oils into products bearing a close resemblance to mineral oil.
The thermodynamic treatment of the reactions involving the reduction of phenol, thiophene, pyridine and aniline, which have been chosen as typical examples of oxygen-, sulphur- and nitrogen-containing compounds, shows that up to 500, under a pressure of 100 atmospheres, the equilibria are greatly shifted towards the formation of water, hydrogen sulphide, ammonia and the saturated hydrocarbons with equal number of carbon atoms as the original compounds.
The author has successfully experimented at 340 and 100 kg. per cm.8, operating in the vapour phase by streaming hydrogen and the product to be treated over cobalt sulphide, used as a catalyst.
Cyclohexane was the main product obtained from both phenol and aniline, whilst pyridine gave chiefly pentane. The hydrogenation of the ring could not be accomplished in the cases of benzene and toluene, which were left unchanged, and of benzilic alcohol, which was merely reduced to toluene, whilst naphthalene gave a certain amount of hydrogenated compounds.
The former result allowed the author to use the catalyst for removing sulphur from benzene charged with thiophene, experimenting under the conditions previously described.
A second set of experiments was carried out with a view to obtaining information on the gasoline yields obtainable from an asphaltic oil produced by retorting the asphaltic rocks of Ragusa (Sicily).
For a few experiments an autoclave was used, and the results were found to be similar to those described by Morgan and Veryard (J. Soc. Chem. Ind., 1932, 51, 81T) when these authors hydrogenated tar oil.
A greater number of experiments were carried out with the apparatus used in the hydrogenation experiments previously described. The oil was injected on the catalyst maintained at constant temperature and on which a current of hydrogen at constant pressure and speed was kept streaming. The oil molecules were thus vaporised and split under conditions most favourable to hydrogenation.
Interesting results were obtained using as a catalyst MOS2 on various supports.
The most active catalyst was found to be MOS$ on silica gel, with which a weight yield of 60% and a volume yield of 84% of gasoline were obtained, by operating at 200 kg. per em 2, 500, and allowing for a time of contact of about 135 seconds; the gasoline which had merely undergone distillation has a waterwhite colour after eight months. The catalyst, however, lost its activity.
The least active catalyst was MoS. on pumice stone; the gasoline yield was only 30% (weight) and 43% (volume) under about the same conditions as m the experiment already reported. By doubling the oil input and re-cycling, a gasoline volume yield of 47% was obtained, the total volume yield of products distilling under 300 being 69%.