Patent GB-722681-A (GB)
Title: Improvements in or relating to sulfur bearing hydrocarbons
IPC: C10M135/04
Filed: 1953-03-12
Abstract: Sulphurized alkyl aromatics are produced by reacting a hydrocarbon feed stock comprising alkyl aromatics (herein defined as single aromatic rings, condensed aromatic rings, naphtheno-aromatic rings and other aromatic systems having at least one long chain alkyl group, i.e. not less than 8 carbon atoms, attached to the ring) or alkyl naphthenic constituents (which dehydrogenate during the reaction to form alkyl aromatics) each having an average molecular weight above 200 (preferably above 300) with sulphur at an elevated temperature for a time sufficient to form a product containing at least 1.5 per cent by weight of chemically combined sulphur, this combined sulphur being in the range of 18 to 33 per cent by weight of the originally added sulphur.  The hydrocarbon feed stocks used should comprise above 15 to 25 per cent of alkyl aromatics or naphthenic compounds; they should be substantially non-olefinic and provided at least 20 to 25 per cent alkyl aromatics are present they may contain paraffinic hydrocarbons as diluents.  The feed stock may be a lubricant base stock, a petroleum base stock, a bright stock derived from a conventionally refined residuum or a synthetic alkyl aromatic hydrocarbon.  Of the latter class particularly suitable are alkyl aromatic hydrocarbons produced by catalytic alkylation of aromatics with high molecular weight olefins, employing boron trifluoride or alumium chloride as catalysts (e.g. a monoalkyl benzene mixture having an average molecular weight of about 275 which consists of the heavier fraction (having 12 to 15 carbon atoms) of the product prepared by alkylating benzene with C12 polypropylene using an aluminium chloride-hydrocarbon complex catalyst).  Other preferred synthetic alkyl aromatic stocks are those produced by a Friedel-Crafts catalytic condensation of long chain aliphatic compounds (i.e. having not less than 8 carbon atoms) such as chlorinated wax (which may be derived from wax distillates or naturally occurring waxes such as palm wax, bees-wax or carnauba wax) with aromatic compounds such as benzene, naphthalene and anthracene, and having a molecular weight above 1000.  Such a Friedel-Crafts condensation product p  may be prepared, for example, by chlorinating paraffin wax and condensing this with naphthalene using an aluminium chloride catalyst and an inert solvent such as a highly refined kerosene, tetrachlorethane and dichlorobenzene.  Useful alkyl aromatics are those with aromatic nuclei such as benzene, biphenyl, naphthalene, anthracene and tetrahydronaphthalene, and with alkyl groups attached to the ring having above 10, and preferably above 15, carbon atoms in straight or branched chain configurations, e.g. dodecyl, tetradecyl, octadecyl, pentacosyl and wax alkyl groups. In carrying out the sulphurization reaction the alkyl aromatic feed stock to be treated may be mixed with 7 to 40 per cent by weight, preferably 10 to 20 per cent by weight (based on the total reactants) of sulphur and the mixture heated to above 370 DEG  F., generally in the range of 400 DEG  to 500 DEG  F. (preferably 420 DEG  to 480 DEG F.) for times ranging from 0.25 to 15 hours (preferably 0.5 to 10 hours) at substantially atmospheric pressure with provisions being made in the reactor for removal of hydrogen sulphide.  If desired, the alkyl aromatic may be heated to reaction temperature before sulphur is added.  The heated hydrocarbon may also be added to hot molten sulphur.  The final product should contain at least 1.5 per cent and preferably above 2 per cent by weight of chemically combined sulphur but sulphur contents much above 10 to 15 per cent by weight will frequently give oil insoluble products.  The reaction may be conducted at lower temperatures (350 DEG  to 400 DEG  F.) and for shorter times by incorporating a small amount of a catalyst or stabilizing agent of the vulcanization accelerator type in the reaction mixture, e.g. using 1 to 20 per cent by weight (based on the sulphur, treat) of tetramethyl thiuram disulphide mercapto benzothiazol, diphenylguanidine, selenium diethyldithiocarbamate, piperidinium pentamethylene dithiocarbamate or mixtures thereof.  The final product may be filtered to remove insoluble reaction products and then blown with nitrogen or other inert gas to remove dissolved hydrogen sulphide or it may be treated with a basic material to remove free acidic compounds.ALSO:A lubricating oil composition comprises a mineral or synthetic base lubricant and a minor amount of a sulphurized alkyl aromatic produced by reacting a hydrocarbon feedstock comprising alkyl aromatics (herein defined as single aromatic rings, condensed aromatic rings, naphtheno-aromatic rings and other aromatic systems having at least one long chain alkyl group, i.e. not less than 8 carbon atoms, attached to the ring) or alkyl naphthenic constituents each having an average molecular weight above 200 with sulphur at an elevated temperature for a time sufficient to form a product containing at least 1.5 per cent. of chemically combined sulphur, this combined sulphur being in the range of 18 to 33 per cent. by weight of the originally added sulphur.  The hydrocarbon feedstocks used should comprise above 15-25 per cent. of alkyl aromatics or naphthenic compounds; they should be substantially non-olefinic and provided at least 20 to 25 per cent. alkyl aromatics are present they may contain paraffinic hydrocarbons as diluents. The feedstock may be a lubricant base stock, a petroleum base stock, a bright stock derived from a conventionally refined residuum or a synthetic alkyl aromatic hydrocarbon such as the product from the catalytic alkylolation of aromatics with high molecular weight olefins or the product from a Friedel-Crofts catalytic, condensation of long chain aliphatic compounds (i.e. having not less than 8 carbon atoms) such as chlorinated waxes with aromatic compounds, the products having a molecular weight above 1,000.  The lubricant base stock may be an engine oil, gear oil or grease ranging from 35 to 150 seconds Saybolt viscosity at 210 DEG F. and may be derived from mineral oils or prepared synthetically, e.g. synthetic lubricants such as conventional polyester and polyether types may be used as base stocks or may be admixed with petroleum base lubricants.  The composition should preferably contain 0.001 to 20 per cent. by weight of the sulphurized alkyl aromatic additive and may also contain dyes, thickeners, viscosity index improvers, oiliness agents, resins and catalysts or stabilizing agents of the rubber vulcanization accelerator type (introduced to assist the sulphurization process) such as tetramethylthiuram disulphide, mercapto benzothiozol, diphenylguanidine, selenium diethyldithiocarbonate, piperidinium pentamethylene dithiocarbamate or mixtures thereof.