Patent GB-779084-A (GB)
Title: Improvements in and relating to the manufacture of highly refined mineral oils and petroleum sulphonates
IPC: C07C309/62
Filed: 1953-07-28
Abstract: Petroleum sulphonates and refined mineral oils (see Group III) are obtained by a process wherein removal of the aromatic hydrocarbons present in a lubricating oil fraction comprising the feedstock is effected by adsorption, for example on silica gel, from a solution of the feedstock in a hydrocarbon diluent solvent which is free or substantially free from unsaturated constituents, the aromatic hydrocarbons being subsequently fractionally desolved and a suitable fraction sulphonated to yield petroleum sulphonates.  Specified absorbents are benzene, methanol and liquid sulphur dioxide.  The preferred aromatic fraction for sulphonation is that which first leaves the adsorption zone on desorption and has a refractive index (sodium D line at 20 DEG  C.) of not in excess of 1.55.  In a preferred procedure a raffinate oil obtained by sulphur dioxide extraction of a suitable vacuum distillate is blended with a diluent petroleum solvent and pumped upward through a column containing silica gel, the presence of aromatic hydrocarbons in the flow from the column being detected by specific dispersion or refractive index measurements, if necessary.  The charging of the feedstock is followed by development with the same diluent solvent to remove paraffin/naphthene constituents from the column.  The development is followed by desorption with benzene, the flow from the column being treated to remove benzene by evaporation and the residue tested for refractive index.  Desorption is continued until the column is substantially free of aromatic hydrocarbons, the column then being ready for a further adsorption cycle.  In an example, a light engine distillate is solvent extracted with sulphur dioxide, diluted with 40-60 DEG  C. petroleum ether and treated as described above.  The desorbed fraction having a refractive index from 1.49-1.54 is sulphonated with sulphuric acid and the sulphonated oil is extracted with aqueous alcoholic sodium hydroxide to give oil-soluble sodium sulphonates.ALSO:Highly refined mineral oils are obtained by a process wherein removal of the aromatic hydrocarbons present in a lubricating oil faction comprising the feed stock is effected by adsorption, for example on silica gel, from a solution of such feedstock in a hydrocarbon diluent solvent, which is free or substantially free from unsaturated constituents.  The aromatic hydrocarbons are desorbed and sulphonated (see Group IV(b)).  The material which is not adsorbed consists essentially of paraffin/naphthene hydrocarbons and after removal of the solvent may be used as a white oil.  The white oil may be further treated with oleum to give a liquid paraffin.  Additional adsorption stages in series may be employed and reduce the amount of oleum required in this treatment.  In a preferred procedure, a raffinate oil obtained by sulphur dioxide extraction of a suitable vacuum distillate is blended with a diluent petroleum solvent and pumped upward through a column containing silica gel.  The presence of aromatic hydrocarbons in the flow from the column may be detected by specific dispersion or refractive index measurements, if necessary.  The charging of the feed stock is followed by development with the same diluent solvent, to remove paraffin/naphthene constituents from the column.  The silica gel is desorbed with benzene until the column is substantially free of aromatic hydrocarbons, the column then being ready for a further adsorption cycle.  The refined mineral oil is obtained from the flow from the column in the adsorption and development stages by removal of the solvent by evaporation.  In examples: (1) a light engine distillate is solvent extracted with sulphur dioxide and the raffinate is diluted with 40-60 DEG C. petroleum ether and treated as described above, the paraffin/naphthene fraction obtained being subjected to a second silica gel adsorption stage, the products of both the first and second stages being treated with oleum; (2) a blend of heavy and light spindle distillates is solvent extracted with sulphur dioxide and dewaxed, the raffinate being treated as described above to yield a white oil.