GB829851A - A process for the catalytic desulphurization of heavy sulhpur-containing hydrocarbonoil fractions - Google Patents

Abstract

A process for the desulphurization of a heavy hydrocarbon oil fraction, of which at least 90% volume boils above 300 DEG C. and not more than 20% volume boils above 500 DEG C., comprises allowing the fraction, while at least partly liquid, to flow downwardly at 10 to 100 atmospheres and 300-500 DEG C. over a fixed catalyst comprising at least one metal or compound thereof from each of Group VI and VIII in the presence of an added auxiliary hydrocarbon oil of lower boiling range which contains at least 0.05% wt. of sulphur and in the presence of an excess of a gas containing a major proportion of hydrogen such that after cooling and removing H2S from the exit gases of the process there remains at least 50 litres gas/Kg. total oil (S.T.P.). The heavy oil and the auxiliary oil may subsequently be separated by distillation with or without vacuum and/or the addition of steam. The treated oil may be obtained by the straight, vacuum, or steam distillation of crude oil which may have been previously dewaxed, deasphalted or extracted. Auxiliary oils mentioned are kerosine and gasoline. They may be straight-run distillates or obtained by applying one or more physical, thermal or catalytic treatments to such a distillate and redistilling. Equal weights of heavy and auxiliary oils may be used. The boiling range of the auxiliary fraction may adjoin or slightly overlap that of the heavy fraction but it is preferably distinctly lower. The preferred catalysts comprise nickel and/or cobalt plus molybdenum and/or tungsten on alumina, the elements being present as metals and/or compounds with one another and/or oxygen and sulphur, particularly 5-15 wt. per cent of cobalt and molybdenum (as metals and/or compounds with each other and/or one or more of the element oxygen, sulphur and aluminium) on alumina wherein the atomic ratio Co : Mo is between 1 : 20 and 18 : 20. The hydrofining is operated by the trickle process wherein the liquid portion of the oil flows in a thin film over a fixed bed of catalyst. The hydrogen-containing gas may be a mixture of hydrogen and light hydrocarbons and usually contains at least 60 volume per cent, preferably more than 80, of hydrogen. It may be passed in counter-current or parallel flow with the liquid oil and may be recycled after removal of H2S. In an example equal weights of a 350-484 DEG C. (I.B.P. to 80%) paraffinic lube oil and a 187-261 DEG C. kerosine are hydrofined at 50 kg/cg. cm. and 385 DEG C. at a space velocity of 1 kg/l/hr. and a H2 rate of 285 l/kg. Specifications 657,521 and 665,575 are referred to.