Selective Synthesis of Distillates by Transfer Hydrocracking of Heavy Oils.

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It was found that a special kind of active carbon, which was activated by proper methods to give high specific surface area, pore volume and high density of radical site and which carry metal or metal sulfate, showed excellent catalytic activity for the transfer hydrocracking of heavy hydrocarbons such as vacuum residue or natural asphalt to make distillate. Cracking of heavy hydrocarbons proceeded both in the oil and on the carbon surface to give paraffins, aromatics, olefins, free radicals and organo-sulfur compounds, with low molecular weight. On the other hand, asphalten, which is high aromatic and high molecular weight, was adsorbed -on active carbon to be decomposed an'd to be dehydrogenated making light hydrocarbons and coke. Hydrogen atoms which was generated during coking moved on the carbon surface to reach metal site. On the metal, some part of hydrogen atoms reacted with olefins or organo-sulfur compounds to make paraffins or de-sulfured compounds, . and other part of hydro … More gen atoms on the metal site combined to fokm hydrogen gas to go out into liquid phase. The latter part of hydrogen movement was a reversible phenomenon. It was controled by the concentratiori of hydrogen in the liquid, which was proportional to the pressure of hydrogen in the gas phase. Therefore'. by conducting the carbon catalyied reaction under certain hydrogen pressure, the hydrocracking of heavy oil proceed without any hydrogen consumption. This concept was confirmed by the reaction of model compounds (diphenyl propane as a hydrogen acceptor and tetra-hydro naphthalene as a hydrogen donor) on the same catalyst.In order to make excellent carbon catalyst, a variety of activation of coal were tried. By treating a coal with hydrogen at high temperature, a porous carbon which has excellent hydrogenation activity, when it carried iron, was made while brown coal was treated with CO_2 at 850ﾟC, a porous barbon which was highly active for cracking heavy oil and for dehydrogenating asphalten was developed. By using tliis carbon (with 5 wt% Fe) complete conversion of vacuum residue of Aravian fleavy Crude was attained to give 80 % oil, 8. % gas and 10 % coke.Based on this concept, a new coal-petroleum co-processing system was postulated. Less