Patent GB-788456-A (GB)
Title: Stabilization of phosphosulphurized hydrocarbons
Inventor: GARBETT THOMAS ARNOLD
IPC: C07F9/02
Filed: 1955-04-19
Abstract: A phosphosulphurized hydrocarbon is stabilized by steam-stripping it at a temperature within the range 200 DEG  to 500 DEG  F., the said steam-stripping being continued at the same rate of stripping for not less than 2 hours after the time at which the rate of loss of the sulphur in the phosphosulphurized hydrocarbon reaches a constant value during the steam-stripping.  The hydrocarbons which are phosphosulphurized are preferably petroleum fractions, particularly lubricating oil fractions such as brightstocks.  Polymers of unsaturated hydrocarbons are also suitable, e.g. those having a mean Staudinger molecular weight of not more than 50,000.  The quantity of steam which is passed is preferably from 0.007 to 2.0 pounds per hour of steam per pound of phosphosulphurized hydrocarbon and when the stripping process is complete it is preferred to pass a stream of an inert gas such as nitrogen through the stripped material while it is cooling. The stabilized product should preferably contain from 2.5 to 4.0 per cent by weight of phosphorus and from 0.5 to 2.0 per cent by weight of sulphur and may be used as an additive for lubricating oils (see Group III).  In examples: (1) 2 lb. of a phosphosulphurized lubricating oil bright stock is heated to 330 DEG  F. in a glass container and 2 lbs./hr. of steam at a temperature of 350 DEG  F. is passed through the material by means of a sparge dipping nearly to the bottom of the container.  Vapours and gases are drawn off through a heated pipe and the contents are continually removed from the bottom of the container and returned to the top of the container so as to ensure thorough contact of all the material with the steam.  A graph is given in which the sulphur content of the steam-stripped product is plotted against the time of steam passage and shows that the rate of loss of sulphur reaches a constant value after 10 hours' treatment.  The steam-stripping is then continued for a further period of at least two hours, e.g. for a total period of 12 hours or 16 hours from the commencement of the steam treatment, to give a stable product which does not evolve any significant quantity of hydrogen sulphide even after standing for one week; (2) steam is passed at a temperature of 390 DEG  to 460 DEG  F. and at a rate of 2 lb. steam per hour through 2 lb. of a bright stock which has been phosphosulphurized by heating with phosphorus pentasulphide at 425 DEG  F. for about 10 hours.  The steam treatment in this case is continued for a total period of 16 hours, the rate of loss of sulphur reaching a constant value after 14 hours treatment.  A drawing is given to illustrate apparatus suitable for carrying out the phosphosulphurization and steam-stripping processes. Specifications 717,675 and 727,573 are referred to.ALSO:A lubricating oil composition comprises a lubricating oil and a phosphosulphurized hydrocarbon which has been stabilized by steam-stripping at a temperature within the range 200 DEG  to 500 DEG  F., the said steam stripping being continued at the same rate of stripping for not less than 2 hours after the time at which the rate of loss of the sulphur in the phosphosulphurized hydrocarbon reaches a constant value (see Group IV (b)).  The lubricating oil is preferably a mineral lubricating oil and the composition should preferably contain not more than 20 per cent by weight, e.g. from 2 to 13 per cent by weight, based on the total composition of the stabilized phosphosulphurized hydrocarbon.  The hydrocarbons which are phosphosulphurized are preferably petroleum fractions, e.g. lubricating oil fractions such as brightstocks, or polymers of unsaturated hydrocarbons, particularly those having a mean Staudinger molecular weight of not more than 50,000.  The quantity of steam used in the stabilization process is preferably from 0.07 to 2.0 pounds per hour of steam per pound of phosphosulphurized hydrocarbon and after the steam-stripping process it is preferred to pass a stream of inert gas such as nitrogen through the stripped material while it is cooling.  In an example, a phosphosulphurized lubricating oil bright stock is stabilized by steam stripping for 12 hours at 350 DEG  F., the steam being passed at the rate of 2 lbs. per hour through 2 lbs. of the phosphosulphurized hydrocarbon and a table is given to show the effect of the stabilized material as an extreme pressure agent when dissolved in a paraffinic mineral lubricating oil. Specification 717,675 and 727,573 are referred to.ALSO:A phosphosulphurized hydrocarbon is stabilized by steam-stripping it at a temperature within the range 200 DEG  to 500 DEG  F., the said steam-stripping being continued at the same rate of stripping for not less than 2 hours after the time at which the rate of loss of the sulphur in the phosphosulphurized hydrocarbon reaches a constant value during the steam-stripping.  The hydrocarbons which are phosphosulphurized may be polymers of unsaturated hydrocarbons, particularly those having a mean Staudinger molecular weight of not more than 50,000.  The rate of steam passage is preferably from 0.07 to 2 pounds per hour of steam per pound of phosphosulphurized hydrocarbon and when the stripping process is complete it is preferred to pass a stream of inert gas, e.g. nitrogen, through the stripped material, while it is cooling.  The stabilized material should preferably contain from 2.5 to 4.0 weight per cent of phosphorus and from 0.5 to 2 weight per cent of sulphur and may be used as an additive for lubricating oils (see Group III).  The steam is preferably passed through the phosphosulphurized hydrocarbon by means of a sparge dipping almost to the bottom of the material.  A drawing is given to illustrate apparatus suitable for carrying out the phosphosulphurization and steam-stripping steps.  Specifications 717,675 and 727,573, [both in Group IV (b)], are referred to.