Improvements relating to reducing the aromatic content of petroleum distillates

摘要

The aromatic content of petroleum distillates boiling within the range 60-250 DEG C. is reduced by firstly catalytically hydrofining to reduce the sulphur content to at most 0.002%, removing dissolved hydrogen sulphide and catalytically hydrogenating the product in the presence of at least 50 litres per kg. of feedstock of excess hydrogen and a supported reduced nickel catalyst preferably at 100-200 DEG C., 70-430 p.s.i.g. and a space velocity of 0.5-5 v/v/hr. to reduce the aromatic content to 1% or below. The hydrogen used in either stage may be pure hydrogen or a hydrogen-containing gas, e.g. from a reforming process; excess hydrogen from the desulphurization step after removal of hydrogen sulphide may be used in the hydrogenation. The preferred desulphurisation catalyst is one of cobalt and molybdenum oxides, as such or combined, supported on alumina. Hydrogen sulphide may be removed by washing with caustic soda or by stripping with steam or an inert gas followed, if necessary, by a light soda wash. In the second step the nickel catalyst may be supported on silica which may contain a minor proportion of cobalt.