US2161987A - Method for improving synthetic hydrocarbon oils - Google Patents

Description

Patented June 13, 1939 METHOD -FOR. IMPROYING SYNTHETIC HYDROCARBON OILS Joshua A. Tilton and Roger W. Richardson, Baton Rouge, La., assignors to Standard Oil Development'Company, a corporation of Delaware No Drawing. Application January '2, 1936,

' Serial No. 57,246

3 Claims.

This invention relates to a method for improving synthetic hydrocarbon oils by subjecting such oils to silent electric discharge. It relates more particularly to the refining of crude syn- 5 thetic oils, especially those having the property of decreasing the pour point of waxy oils when added thereto in small amounts. Such oils are conveniently described as pour point depressants.

The treatment of petroleum oils by silent elecl" tric discharge, or voltolization, to increase their viscosity, has already been suggested. Such treatment may be conducted in any suitable ap ratus for bringing the oil in contact with a silent electric discharge. It is conveniently 5 conducted in a Siemens ozonization tube or in a trommel type voltolizer, in which a thin film 01 oil is continuously passed between electrodes in a reaction chamber maintained under an absolute pres-ure'ot about 2 to or cm. of mercury,

20 with an electric potential of about 1,000 to 10,000

volts or more at a frequency 01' about 500 to 10,000

cycles per second, the potential and pressure and space between electrodes being adjusted so as'to obtain continuous silent electric discharge.

It has how been foundthat the synthetic hydrocarbon'oil pour point depressants are greatly improved by submitting such oils, to treatment with the silent electric discharge. By this treatment highly refined synthetic oils may be obtained directly from the crude synthetic reaction productswithout the necessity of other renow commonly used. Such prod- .ucts are-also obtained in greater yields since the process of .the present invention is attended by none of the lgiises .1 0 low quality or objectionable by-pr'oducts such as accompany ordinary treating and refining methods.

When synthetic oils are subjected to relatively intensive treatment with silent electric discharge,

40 the molecular weight and viscosity of the oils are increased several told, and products of high molecular weight of the order of-1,000 to 2,000 more, and'o! high viscodties of the order oi 500 to.1,000 or more seconds Saybolt at 210" F., are

obtained. Such products are especially suited for use as blending agents with lubricating oils in order to produce blends of higher viscosity and viscosity index, and are suitably used in proportions of 5, 10, 20 to or more with 50 lubricating oils, such as ordinary petroleum. lu-

bricating oils. Small amounts of these voltolized syntheticoils of the order of 1, 5 to 10% may 'also be used as. oxidation inhibitors in lubricating oil blends, particularly with lubricating oils having high rates of oxidation, such as petroleum lubricating oils which have been extensively r'efined with fuming sulfuric acid or by other refining methods adapted to increasesubstantially the viscosity index of the oil.

This invention comprises subjecting the syn-. thetic oils to a mild treatment with silent electric discharge whereby any increase in viscosity Q! ,molecular weight of the oils is relatively small and these are preferably not more than doubled. The increase in viscosity is generally not more than 10 to 50 or By this modification the objectionable qualities of the impurities normally present in such oils are greatly decreased or eliminated and many properties of the synthetic oils are greatly improved, such as color, cast, solubility and other special properties. For example,

. the effectiveness of synthetic pour inhibitors is increased by this treatment to an aptimum extent when the increase in viscosity by the action of silent electric discharge is about 100% but less than 200% and preferably less than about Other and further objects of this invention will be apparent from the resent description and the claims.

The property of certain types of condensatio products of decreasing the pour point (or solidification point) of waxy lubricating oils when ,added thereto in small amounts is well known. Such condensation products are known as pour point depressants or "pour inhibitors. These products are usually viscous oils. They are described more fully in U. S. Patent No. 1,815,022 granted July 14, 1931, to G. H. B. Davis. Examples of such oils include alkyl-aryl condensation" .products which are preferably prepared by condensation of aliphatic reagents having a straight carbon chain of 10 t6 30 or more carbon atoms with aromatic reagents containing condensed nuclei. An example 01' this type of condensation product is the viscous oil obtained by condensing chlorinated parafliruwax with naphthalenes by the Friedel-Crafts reaction, in the presence of a catalyst of the type of aluminum chloride.

It has now been discovered that the properties of such pour depressants are markedly'improved by subjecting the condensation products to the action of a silent electric discharge. This treatment is preferably niild, as described above under The following examples are presented to illustrate one method for conducting this modificatnm of this invention, but are not to be construed as limiting the-invention in any way.

Example I ride to a solution of the reagents in kerosene at room temperature. The reaction mixture was then washed with aqueous caustic soda to neutralize any residual aluminum chloride, and the aqueous layer containing the aluminous sludge charge in the was settled and separately drawn off. The oil layer was then distilled to remove the kerosene and any unreacted paraflin there was obtained as residue a viscous synthetic hydrocarbon oil condensation product. This product, dissolved in kerosene, was agitated with a decolorizing clay, which was filtered oil and the kerosene again removed by distillation. There was thus obtained as distillation residue an oil having a Saybolt viscosity of 297 seconds at 210 F. and a black, almost opaque color.

This condensation product was then subjected to the action of srllent'electric discharge in a Siemens ozonization tube at a pressure of '2 cm. of mercury absolute, using an electric potential of 2,000 to 2,500 volts at 10,000 cycles per second. The apparatus was a vertical annular glass tube with concentric electrodes on both outside walls. Hydrogen was bubbled through the oil to maintain it in a state of foam. The treatment was continued for about 5 hours in order to secure an increase in viscosity of about 100%.

The resulting product had a light clear red color with a green cast, and a viscosity of 599 seconds at 210 F.

Portions of the original condensation product,

and of the product after subjection to the silent electric discharge were each added to light and heavy waxy oils. .The characteristics of the original oil andthe resulting blends are shown in the following table:

Light oil Heavy oil Waxy oils:

Viscosity, seconds Saybolt@2l0 F.. 44 70 Viscosity index 100 100 Pour point, F 30 30 +04% condensation product:

- Pour point, 4 -l0 +04% voltolized condensation product: Iour point, F a0 The crude condensation product, prepared as described in the above example, may be subiected after the separation of aluminum chloride sludge and without further finishing, directly to voltolization to produce similar pour depressants of improved color and increased effectiveness. In this'manner ordinary treating and refining losses, which are substantial and may amount to as high as 25% or more,'are avoided.

While' the treatment with silent electric disabove example produced an increase of about 100% in'the viscosity of the synthetic oil, much-milder treatments at lower voltages,

lower frequencies and/orv for shorter periods of] increase of not over 10 time, which produce an the synthetic oil, also as distillates, and

- shown in Example I and a pour point of with the heavy oil shown in Example I. It is I approximately depressants generalm.

serve to refine the oil and to produce substantial improvements in its appearance and blending characteristics with petroleum lubricants. The color of the oil is substantially improved even by such mild treatment with silent electric discharge that the viscosity of the oil is increased only 1 or 2%. More intensive treatments at higher voltages, frequencies and/or for longer periods of time may=also be used, but these are not generally desirable when an improved pour point depressant adaptable for use in all waxy oils is desired. It has been observed that the effectiveness of the voltolized pour point depressant in waxy oils of low viscosity is impaired if the voltolization treatment is made too intensive. For example, when the voltolization of the synthetic oil described in Example I is continued until the voltolized product has a viscosity of 711 seconds Saybolt at 210 F., (corresponding to an increase of about 140% in the viscosity of the synthetic oil), a 0.4% of this product produces a blend having a pour point of 10 F. with the light oil F.

thus apparent, that too intensive voltolization results in a pour depressant which is less effective in certain lubricating oils.

The voltolization of the above example may also be continued so as to produce an improved cosity several times greater than that of the original 011. For example, the voltolization treatment described in Example I may be continued until a voltolized synthetic product having a viscosity above 1,000 to 2,000 seconds Saybolt at 210 F. is produced. This highly viscous product is also of superior color and is suitable for use as a blending agent with other lubricating oils, particularly those derived from petroleum, in order to increase the viscosity and viscosity index of such oils and/ or as an oxidation inhibitor.

The apparatus used in the present process may be of the usual type of tube or trommel design. The tube type of apparatus comprises a vertical tube preferably constructed of a dielectric material such as glass coated on the outside with a conductor electrode, a central electrode disposed in 'the center of this tube, provision being made for a high tension silent discharge between the electrodes. The trommel type of apparatus comprises a series of insulated plates placed a few millimeters apart and mounted on a rotatableshait, the entire shaft with its plates being disposed within a horizontal drum maintained half full of the material to be voltolized. The bottom portions of the plates dip into the material to be voltolized and as the shaft rotates, the material drips down over the surface of the plates forming a thin film thereon. The high tension silent discharge occurs between the plates. In apparatus of this type it is generally preferred to operate at a pressure below about 20 cm. of mercury and preferably about 2 to 10 cm. and at an electrode potential of about 1,000 to 10,000 volts or more at a frequency of about 500 to 10,000 cycles or more per second.

The treatment with silent electric discharge may be conducted. in the-presence of hydrogen product having a isthe synthetic oil shown in g or other preferably reducing gases, such as carbon monoxide, natural gas or other hydrocarbon gases or vapors, water gas, coke oven gases and the like.

' The present invention is applicable to the improvement of-synthetic hydrocarbon pourpoint including those prepared by the Friedel-Crafts, Fittig, Wurtz and other types of syntheses. For example, the synthetic pour point depressants described in U. S. Patent No, 1,815,022 granted July 14, 1931, to G. H. B. Davis, and in British Patent No. 349,071 accepted May 11, 1931, may be improved bytreatment with silent electric discharge according to the present invention.

This invention is not to be limited to any examples or explanations, all of which are presented herein solely for purpose of illustration, but is limited only by the following claims, in which it is desired to claim all novelty insofar as the prior art permits.

We claim:

1. Process for improving an unrefined synthetic hydrocarbon pour point depressant prepared by chemical condensation from an aliphatic reactant having about 10 to carbon atoms in a straight chain to give the pour point depressant improved color and potency marked by increased effectiveness in lowering the pour point of a wax-com taining oil having a Saybolt viscosity of seconds at 210 F. which comprises voltolizing the crude pour point depressant product by the action of silent electric discharges until the viscosity of the resulting voltolized product is about higher but less than about higher than the viscosity of said crude pour point depressant product.

2. Process for refining a crude black alkylactant with an aliphatic reactant having a straight chain of 10 to 30 carbon atoms which comprises subjecting said crude condensation product to the action of silent electric discharges until the thus treated condensation product is given a clear red. color and a green cast with an increase of its viscosity limited to about 100%.

3. Process for refining a crude black pour point depressant synthesized by the condensation of chlorinated paraffin wax with an aromatic hydrocarbon to make an improvement in the color of the pour point depressant and in its effectiveness for lowering the pour point of a heavy waxcontainin oil having a Saybolt viscosity of about 70 seconds at 210 R, which comprises voltolizing said crude pour point depressant by the action of silent electric discharges, and discontinuing the voltolizing when the increase in viscosity of the voltolized product is about 100% but less than 140% above that of the crude pour point depressant.

JOSHUA A, TILTON. ROGER W. RICHARDSON.