CA1113880A

CA1113880A - Removal of non-paraffinic hydrocarbons from paraffinic hydrocarbons

Info

Publication number: CA1113880A
Application number: CA301,728A
Authority: CA
Inventors: Miron Abramovici; Umberto Viani; Paul N. Rylander
Original assignee: Engelhard Minerals and Chemicals Corp
Current assignee: Engelhard Minerals and Chemicals Corp
Priority date: 1977-04-29
Filing date: 1978-04-21
Publication date: 1981-12-08
Also published as: IT7849131A0; JPS5416403A; GB1583118A; DE2818823A1; FR2388875A1; FR2388875B1

Abstract

REMOVAL OF NON-PARAFFINIC HYDROCARBONS
FROM PARAFFINIC HYDROCARBONS
Abstract of the Disclosure Non-paraffinic hydrocarbons, such as aromatic hydrocarbons, in a stream of paraffinic hydrocarbons are removed by contacting the paraffinic hydrocarbon stream with an oxidation system comprising an aqueous solution of hypochlorite, such as sodium hypochlorite, and a ruthenium species, such as ruthenium dioxide, as the oxi-dation catalyst. The ruthenium species is oxidized by the hypochlorite to a higher oxidation state with resulting selective oxidation of the non-paraffinic hydrocarbons to water-soluble non-paraffinic compounds and/or CO2. A
stream of paraffinic hydrocarbons substantially free of non-paraffinic hydrocarbons is recoverable..

Description

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This invention relates to the selective oxidation of non-paraffinic hydrocarbons. More particularly, this invention relates to the selective oxidation of aromatic - compounds, particularly aromatic hydrocarbons includiny aliphatic-substituted aromatic hydrocarbons, e.g. alkyl-substituted aromatic hydrocarbons~and polycyclic aromatic hydrocarbons.

;~ It is known that ruthenium tetroxide is a powerful oxidizing agent, see U.S. Patents 3,409,649 (1968) and ~10 3,479,403 (1969), also J.O.C. 33, 1959 (1968), the article by J. ~. Caputo ot al, olltitled "Synthesis and Ionization .,, . .
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1~13~1B~9 Constants of meta- and para-substituted cis-3-Phenylcyclo-butanecarboxylic Acids" and Tetrahedron Letters- 47, 4729 (1967), the article by J. A. Caputo et al, entitled "The Oxidation of Cyclobutanols and Aromatic Rings with Ruthenium Tetroxide".

It is known that saturated aliphatic or paraffinic hydrocarbons, particularly n-paraffinic hydrocarbons, such as liquid n-paraffinic hydrocarbons having a carbon content up to C23, such as in the range C7-C18, are useful as sub-strates or feedstock for the production of a single cell protein (SCP) involving the growth of selective microorganisms on such substrates, see Hydrocarbon Processing, pages 104-108, March 1969.

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In the utilization of paraffinic hydrocarbons as a substrate for the growth of microorganisms for the produc-:.; tion of SCP, it is desirable that the paraffinic hydrocarbons . so employed be substantially free of non-paraffinic hydro-carbons, particularly with respect to being substantially free of aromatic compounds, such as aromatic hydrocarbons, or have an aromaticcompound or non-paraffinic hydrocarbon content such that the growth of the microorganisms is not ~¦ inhibited and/or the SCP material produced is readily har-vested and is free of any undesirable materials, such as aromatic compounds.

It is an object of this invention to provide a method for the selective oxidation of one hydrocarbon type ovcr anothcr hyclL-ocarbon type.

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It is another object of this invention to provide a method for the separation of non-aliphatic and/or non-saturated hydrocarbons, particularly aromatic hydrocarbons, from saturated aliphatic hydrocarbons.

How these and other objects of this invention are achieved will become apparent in the light of the accompanying disclosure and with reference to the accompany-ing drawing wherein is illustrated a process flow scheme in accordance with this invention for the removal of aromatic hydrocarbons from an n-paraffinic hydrocarbon stream.

In accordance with this invention, it has been disco~ered that a high oxidation state ruthenium species, i.e. higher than ruthenium dioxide, is useful as an oxidiz-ing agent for the selective oxidation of non-aliphatic and/or non-saturated hydrocarbons, particularly aromatic compounds, such as aromatic hydrocarbons, in the presence of saturated aliphatic hydrocarbons, such as n-paraffins.
The aromatic compounds, e.g. aromatic hydrocarbons which may be present as an undesirable component in an aliphatic paraffinic hydrocarbon stream, such as n-paraffinic hydro-carbon-containing stream, are removed during or after oxidation.

More specifically, in accordance with one embodiment of the practices of this invention a stream, such as a hydro-carbon stream containing saturated aliphatic hydrocarbons together with non-saturated and/or non-aliphatic compounds, e.g. hydrocarbons, particularly aromatic compounds, such as ' !
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aromatic hydrocarbons, is contacted with a mixture comprising a low oxidation state ruthenium species, e.g. ruthenium dioxide, and an aqueous hypochlorite solution, such as an aqueous sodium hypochlorite solution. The ruthenium species, e.g. ruthenium dioxide, in the presence of the aqueous hypo-chlorite solution is converted to a higher oxidation state ruthenium species. In turn, the higher oxidation state ruthenium species selectively oxidizes those compounds other than the saturated aliphatic hydrocarbons, such as the aromatic compounds and aromatic hydrocarbons, with the re-sulting conversion of the aromatic compounds and aromatic hydrocarbons to compounds which are readily removable, such as carbon dioxide and/or water-soluble oxygenated derivatives.
More than one higher oxidation state ruthenium species, such as ruthenates, perruthenates and mixtures thereof, may be present or employed in the practices of this invention.

In the above-described treatment, aliphatic paraffinic hydrocarbons, particularly the n-paraffins, are refractory and are not, or tend not to be, oxidized, with the result that the non-aliphatic and/or non-saturated compounds, e.g. aromatic hydrocarbons, present along with the saturated aliphatic or paraffinic hydrocarbons are selectively oxidized. In the above-described operation involving selective oxidation of the non-aliphatic and/or non-saturated compounds in the presence of the paraffinic hydrocarbons, particularly n-paraffinic hydrocarbons, the high oxidation state ruthenium species which is derived from the admixture of a low oxidation state ruthenium species, such as Ru02, and aqueous hypochlorite ''' .

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solution, is reconverted to the corresponding low oxidation state ruthenium species, such as Ru02, which, in turn, is reoxidized in the presence of the aqueous hypochlorite solu-tion to additional higher oxidation state ruthenium species which is again utilized as the active oxidizing agent for the selective oxidation of the above mentioned compounds in the presence of the paraffinic hydrocarbons. Accordingly, only a small or catalytic amount of the low oxidation state ruthenium species, such as Ru02, need be present along with the aqueous hypochlorite solution in the practices of this invention. As indicated, the ruthenium dioxide is present in small, catalytically effective amounts; however, the aqueous hypochlorite solution is employed in substantially stoichiometric amounts relative to the compounds, e.g.
aromatic hydrocarbons, undergoing oxidation; usually desirably the hypochlorite is present or utilized in stoichiometric excess.
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The overall chemical reaction sequence in accordance with the practices of this invention may be exemplified as set forth hereinbelow:

n-paraffinic n-paraffins + C02 and aromatic + (Ru02 + NaOCl ~ Ru04 + NaCl) ~ + water-soluble hydrocarbons oxygenated compounds Aromatic compounds and hydrocarbons which are selectively oxidized include the substituted monocyclic aromatic compounds and hydrocarbons, such as the aliphatic-substituted benzenes, e.g. alkyl-substituted benzenes, the alkenyl-substituted benzenes, the polycyclic aromatic com-pounds and hydrocarbons including the fused polycyclic or ., ~ 5-,:
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polynuclear aromatic compounds and hydrocarbons and derivatives, e.g. naphthalene, anthracene and phenanthrene, and the unfused polynuclear aromatic compounds, such as the biphenyls, and the corresponding aliphatic hydrocarbon.
substituted polycyclic or polynuclear aromatic hydrocarbons.
- Of special interest would be those aromatic compounds and hydrocarbons which have a boiling point in the boiling point range of aliphatic paraffinic hydrocarbons having a carbon atom content in the range of about C6 to about C23, more or less. Of special interest would be those aromatic hydro-carbons which have a boiling point in the boiling point range of the C7-C18 normal paraffinic hydrocarbons.
., The saturated or paraffinic aliphatic hydrocarbons, which are refractory to oxidation in the practices of this ,~
invention, include, as indicated hereinabove, the aliphatic paraffinic hydrocarbons, particularly the n-paraffinic hydro-carbons or n-alkanes. Saturated aliphatic hydrocarbons having a carbon content in the range from about C6 up to about C23 containing in admixture therewith minor amounts of other non-saturated and/or non-aliphatic hydrocarbons which may also possess the same above-mentioned carbon content, e.g. aromatic hydrocarbons, usually below about 10% by weight, e.g. in the range 0.001 to about 2-5% by weight, are usefully treated in accordance with the practices of this invention.

The saturated aliphatic hydrocarbons, useful for the treatment in accordance with the practices of this inven-tion, include the normally liquid saturated aliphatic hydro-carbons, particularly the normally liquid n-paraffinic or straight chain paraffinic hydrocarbons, i.e. such hydrocarbons :
;` having a melting point up to about 100C., more or less, such as a melting point in the range about -100 to about A
-~ As indicated hereinabove, in the practices of this invention the oxidation of the non-aliphatic and/or non-saturated compounds, such as aromatic hydrocarbons, in the presence of saturated aliphatic hydrocarbons, such as the n-paraffinic hydrocarbons, is carried out by employing as the oxidizing agent a mixture of one or more ruthenium species or compound of a relatively low oxidation state, such as ruthenium dioxide, and an aqueous hypochlorite solu-tion. The aqueous hypochlorite solution, as also indicated hereinabove, may comprise an aqueous alkali metal hypo-chlorite solution, such as aqueous sodium hypochlorite, aqueous potassium hypochlorite or mixtures thereof, or may comprise an aqueous alkaline earth me*al hypochlorite, such as calcium hypochlorite, or mixtures thereof or with an aqueous alkali metal hypochlorite. Mixtures of one or more of the above-described hypochlorites, including hypochlorous acid, are useful in the practices of this invention. It is .:, preferred, however, to employ aqueous sodium hypochlorite, such as an aqueous sodium hypochlorite solution having a concentration in the range of about 0.1 to about 15-20~ by weight and at a suitable pH, such as a pH in the range from about 5 to about 11. The above-indicated hypochlorite solu-tion concentration range and pH would encompass suitable aqueous hypochlorite solutions derived from hypochlorites other than sodium hypochlorite and mentioned hereinabove.
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The ruthenium species, such as ruthenium dioxide, employed in combination with an aqueous hypochlorite solu-tion is preferably finely divided. Initially, if desired and as indicated hereinabove, instead of ruthenium dioxide other ruthenium species, organic or inorganic, might be employed. Specifically, any organic or inorganic ruthenium salt which has an anion which does not retard the formation of the desired higher oxidation state ruthenium species oxidizing agent in the presence of hypochlorite solution would be useful, such as ruthenium halides, e.g. ruthenium trichloride. The above-identified patents, U.S. 3,409,649 and U.S. 3,479,403, contain a listing of ruthenium compounds, other than ruthenium dioxide, which are useful in the selective oxidation operation in accordance with this invention.

The selective oxidation reaction involving contact between the saturated aliphatic (straight chain paraffinic) hydrocarbon stream to be treated and purified and the aqueous hypochlorite solution is conveniently carried out at ambient pressure, although subatmospheric or superatmospheric pressures may be employed during the reaction. The reaction is also conveniently carried out at ambient temperatures, such as a temperature at which the hydrocarbons undergoing treatment are maintained in liquid phase, such as a temperature of about 15-30C., more or less. If desired~ a lower reaction or con-tacting temperature, such as a temperature as low as about 10C. or lower, or a higher reaction or contacting temperature as high as 75C. or higher, might be employed depending upon the makeup of the hydrocarbons undergoing treatment and the makeup of the hypochlorite solution employed in combination ~ ?~

with the ruthenium species or compound for effecting the selective oxidation of the non-aliphatic, non-saturated hydrocarbons. The reaction should desirably be carried out under conditions such that intimate contact is effected between the hydrocarbons in the liquid phase with the selective oxidizing system comprising the ruthenium species or compound (ruthenium dioxide) and the hypochlorite. In general, however, any suitable, practical operating tempera-ture may be employed in the practice of this invention.

A suitable technique for effecting reaction between the hydrocarbon stream undergoing treatment and the ruthenium-hypochlorite oxidizing system would involve the addition of the hydrocarbons and the ruthenium-hypochlorite oxidizing system to a reactor while the resulting reaction admixture is vigorously agitated. In this operation, only a small catalytic amount of the ruthenium component of the oxidizing system need be employed. The hypochlorite component of the oxidizing system, as indicated hereinabove, can be added continuously or intermittently or substantially all at one time. Since the ruthenium component need only be employed in small catalytic amounts and the higher oxidation state ruthenium active oxidizing agent is regenerated during the reaction in the presence of the hypochlorite, the reaction is essentially controlled by the amount of hypochlorite added or present during the reaction. If a stoichiometric amount of hypochlorite, e.g. sodium hypochlorite, is added relative to the compounds or hydrocarbons yndergoing oxidation, upon completion of the reaction the added hypochlorite should be converted to the corresponding salt, such as sodium hypochlorite to sodium ~:. . - ., :
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1~3~3 chloride, and the ruthenium compound employed, such as ruthenium dioxide, would appear as a solid, finely divided ruthenium dioxide.

The contacting of the hydrocarbon stream with the ruthenium-hypochlorite oxidizing system may be carried out in a batch, single-step contacting operation or in a con-current contacting operation or a countercurrent contacting operation, such as in a tower packed with a permeable mass of solid contact material. In general, any suitable means or technique for effecting liquid-liquid and/or liquid solids contact would be suitable for use in the practices of this invention.

Upon completion of the reaction with resulting conversion of the contaminating materials to be removed, such as aromatic hydrocarbons, to innocuous products or products which are readily removed, such as carbon dioxide or water-soluble oxygenated compounds, the resulting reac-tion admixture would be recovered and segregated. The resulting treated hydrocarbons in the reaction mixture, now comprising substantially only saturated aliphatic hydro-carbons, e.g. n-paraffinic hydrocarbons, are withdrawn as product after settling or separation from the aqueous phase, such as the aqueous phase containing also the aqueous hypo-chlorite or the depleted aqueous hypochlorite, i.e. sodium chloride derived from sodium hypochlorite and the ruthenium species or compound employed, e.g. finely divided solid ruthenium dioxide. This aqueous phase containing aqueous sodium chloride and finely divided ruthenium dioxide is then ~13~
further treated, such as by filtration, for the removal of the solid ruthenium dioxide which could be returned to the reactor for contact with additional aqueous hypochlorite to react or treat additional hydrocarbons in accordance with the practices of this invention. The remaining segre-gated or separated aqueous phase, which would contain, for example, sodium chloride and water-soluble oxygenated derivatives of the hydrocarbons undergoing oxidation, could then be separately treated for the recovery of any values therefrom.

Reference is now made to the drawing which schematically illustrates one embodiment of the practices of this invention directed to the selective oxidation of aromatic hydrocarbons in the presence of n-paraffins.

As illustrated in the drawing, an aromatic hydro-carbon-containing n-paraffin stream from a suitable source, not shown, is supplied via line 10 to reactor 11 wherein it is intimately mixed, employing agitator 12, with an admixture of ruthenium dioxide supplied from a suitable source, not shown, via line 14 with aqueous hypochlorite solution, such as an aqueous sodium hypochlorite solution supplied from a suitable source, not shown, via line 15, the resulting admix-ture of ruthenium dioxide and aqueous sodium hypochlorite being supplied to reactor 11 via line 16 for reaction with the aromatic hydrocarbons within reactor 11. Vent line 18 is provided in the upper portion of reactor 11 to avoid any undue pressure build-up within reactor 11.
There is withdrawn from the bottom of reactor 11 via line 19 a reaction admixture comprising the n-paraffinic hydro-carbons, ruthenium dioxide and depleted aqueous hypochlorite ,:
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(sodium chloride). This reaction admlxture is supplied via line 19 to oil-water separator 20 wherein, upon settling, the resulting treated hydrocarbons, now comprising substan-tially only n-paraffins, substantially free of aromatic hydrocarbons, are removed from the upper portion of separator 20 via line 21. An aqueous phase comprising finely divided ruthenium dioxide and sodium chloride is recovered from the bottcm of aeparator 20 via line 22 and passed to ruthenium dioxide separator or filter 24 from which the ruthenium dioxide is separated and recovered via line 25.
The resulting. recovered ruthenium dioxide is recycled via lines 25, 15 and 16 to reactor 11 along with additional fresh aqueous sodium hypochlorite supplied to reactor 11 in combination with the ruthenium dioxide via lines 15 and 16.

There is withdrawn from ruthenium dioxide separator or filter 24 a separated aqueous phase or filtrate via line 26 comprising the depleted aqueous sodium hypochlorite solution (now aqueous sodium chloride) along with any water-soluble oxygenated compounds produced within reactor 11 by the selective oxidation of the aromatic hydrocarbons by the ruthenium tetroxide which is generated within reactor 11 by the combination of ruthenium dioxide and aqueous sodium hypochlorite.

The above-described embodiment in the practice of this invention made with reference to the drawing is particularly applicable to a batch operation or process for .removal of contaminating materials from an n-paraffinic hydrocarbon stream.

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The following is an example of one embodiment (batch process) of the practices of this invention for the removal of aromatic hydrocarbons from an n-paraffinic hydro-carbon stream, the n-paraffinic hydrocarbons being comprised of n-paraffins having a carbon atom content (per molecule) in the range from about C8 to about C16 and containing a minor amount of aromatic hydrocarbons in the range of about 0.01-0.5 to about 2.5% by weight of the stream. The n-paraffinic hydrocarbon stream in the amount of about 50 barrels (U.S.) is introduced into a reactor where it is mixed vigorously with an aqueous admixture comprising ruthenium dioxide and aqueous sodium hypochlorite. The aqueous sodium hypochlorite is added in an amount in stoichiometric excess relative to the aromatic hydrocarbons to be oxidized and removed. The added aqueous sodium hypochlorite solution conveniently has a concentration of about 5% by weight sodium hypochlorite and is at a pH of about 9.5. As indicated, finely divided ruthenium dioxide is added in a small amount, about 0.5-10 pounds, more or less, along with the aqueous hypochlorite solution to contact the hydrocarbons within the reactor.

The reactants supplied to the reactor and the resulting reaction admixture during the oxidation reaction (selective oxidation of the aromatic hydrocarbons) are usually at about ambient temperature or slightly more or less than ambient temperature, such as in the range of 10-50C., more or less, depending upon the amount of aromatic hydrocarbons in the hydrocarbon stream undergoing reaction and the temperature of the reactants supplied to the reactor.

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Carbon dioxide formed due to oxidation of the aromatic hydro-carbons along with other gases or vapors which might be formed are vented upon the reactor.

Upon completion of the reaction which is carried out with vigorous agitation, usually after contacting the reaction mixture for a short period of time, about five minutes to about one hour, the resulting reaction mixture is withdrawn and the hydrocarbon phase separated from the aqueous phase. The resulting separated hydrocarbon phase now has a substantially reduced aromatic hydrocarbon content.
The aqueous phase containing sodium hypochlorite solution and the ruthenium oxidizing species is treated with sufficient reducing agent, e.g. methanol, to reduce the ruthenium oxidizing species to ruthenium dioxide and the sodium hypo-chlorite to sodium chloride. The resulting admixture is filtered for the removal of ruthenium dioxide which can be returned to contact additional hydrocarbons for the oxidation of aromatic hydrocarbons along with added additional aqueous sodium hypochlorite.

In this example or embodiment of the practices of this invention, the treatment of the aromatic-containing hydrocarbon stream, which is comprised predominantly of n-paraffinic hydrocarbons, is carried out batchwise, i.e.
all the reactants, preferably in the desired amount, are added at substantially the same time to the reactor. If desirable or preferred, upon the addition of the hydrocarbons to be treated substantially all of the ruthenium dioxide can be added directly thereto separately or in admixture with the ., : .

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aqueous sodium hypochlorite solution which could be then added gradually continuously or intermittently for a period of time until the desired stoichiometric excess amount of aqueous hypochlorite has been added, effective, in combina-tion with ruthenium dioxide, to complete the oxidation of the aromatic hydrocarbons. If desired, instead of adding the hydrocarbons to be treated all at once or batchwise, the hydrocarbons may be added over a period of time, inter-mittently or continuously, to an admixture of ruthenium dioxide and aqueous sodium hypochlorite. Under such con-ditions, the aromatic hydrocarbons in the n-paraffinic hydrocarbon stream would be rapidly oxidized.

Obviously, many variations of the above and other techniques for bringing the reactants together for effecting the oxidation of the undesirable contaminating components are suitable in the practices of this invention. In the practice of this invention, as indicated hereinabove, it is desirable to add only sufficient aqueous hypochlorite solu-tion to generate the powerful active high oxidation state ruthenium species oxidizing agent, e.g. ruthenium tetroxide, and to replenish the same until the contaminants in the n-paraffinic hydrocarbon stream undergoing treatment have been removed by oxidation or converted to readily removable water-soluble oxygenated compounds.

Although in the practices of this invention ruthenium dioxide is the preferred low oxidation state ruthenium compound or species employed in association with the aqueous hypochlorite solution, e.g. aqueous sodium -15_ ~3-~`lg hypochlorite, for the production of a relatively high oxida-tion state ruthenium compound or species, as indicated hereinabove, other ruthenium compounds or species are also usefully employed in association with the a~ueous hypochlorite solution for the production of the higher oxidation state ruthenium species. Other suitable ruthenium compounds include the ruthenium halides, e.g. ruthenium trichloride, and other inorganic ruthenium salts, as well as the ruthenium salts of fatty acids, such as the C2 and higher fatty acids, ruthenium acetate, ruthenium propionate and ruthenium butyrate.
For a larger listing of suitable ruthenium compounds includ-ing ruthenium-containing chelates useful in the practices of this invention, see U.S. 3,409,649 as mentioned hereinabove.

Although emphasis has been placed on the selective oxidation of aromatic hydrocarbons in the presence of saturated aliphatic hydrocarbons in the practices of this invention, compounds other than saturated aliphatic compounds or, more particularly, organic compounds other than saturated aliphatic hydrocarbons, are also suitably removed by selective oxidation in accordance with the practices of this invention.
For example, compounds other than saturated aliphatic hydro-carbons which would appear to be selectively oxidized in accordance with the practices of this invention in the presence of saturated aliphatic hydrocarbons, particularly n-paraffinic hydrocarbons, include aromatic compounds, substituted aromatic hydrocarbons, unsaturated aliphatic compounds, including unsaturated aliphatic hydrocarbons, cycloaliphatic compounds, including cycloaliphatic hydrocarbons, saturated or unsaturated.
In general, the practices of this invention are particularly 1~3L3~

applicable for the removal by selective oxidation of con-taminating compounds in the presence of saturated aliphatic compounds, particularly n-paraffinic hydrocarbons.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many modifications, alterations and substitutions are possible in the practice of this invention without departing from the spirit or scope thereof.

. .

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of removing aromatic hydrocarbons from a liquid mixture of aromatic hydrocarbons and paraffinic hydrocarbons which comprises contacting said mixture with an oxidation system comprising ruthenium in a low oxidation state as the dioxide and at least a stoichiometric amount of an aqueous hypochlorite solution relative to the aromatic hydrocarbons in said mixture under conditions such that the mixture of hydrocarbons is brought into intimate contact with a catalytic amount of ruthenium in a high oxidation state and at least a stoichiometric amount of said aqueous hypochlorite solution to obtain selective oxidation of the aromatic hydrocarbons to carbon dioxide and/or water-soluble oxygenated aromatic hydrocarbons and recovering paraffinic hydrocarbons substantially free of aromatic hydrocarbons.

2. A method in accordance with claim 1 wherein said mixture of aromatic and paraffinic hydrocarbons contains a minor amount of aromatic hydrocarbons.

3. A method in accordance with claim 1 wherein said aqueous hypochlorite solution is an aqueous solution of sodium hypochlorite.

4. A method in accordance with Claim 3 wherein said aqueous sodium hypochlorite solution contains an amount of sodium hypochlorite in the range of about 0.01-0.1 to about 15% by weight.

5. A method in accordance with Claim 1 wherein said aqueous hypochlorite solution is an aqueous calcium hypochlorite solution.

6. A method in accordance with Claim 1 wherein said aqueous hypochlorite solution contains calcium hypo-chlorite in an amount in the range 0.1-20% by weight.

7. A method in accordance with Claim 1 wherein said aqueous hypochlorite solution contains potassium hypochlorite.

8. A method in accordance with Claim 1 wherein the pH of said aqueous hypochlorite solution is in the range from about 5 to about 11.

9. A method in accordance with Claim 1 wherein the contacting of said mixture of aromatic hydrocarbons and paraffinic hydrocarbons with said oxidation system is carried out at a temperature in the range from about 10°C.
to about 75°C.

10. A method in accordance with Claim 1 wherein said aromatic hydrocarbons are present in said mixture in a minor amount up to about 10% by weight.

11. A method in accordance with Claim 1 wherein said aromatic hydrocarbons are present in said mixture in an amount in the range from about 0.00001-0.0001% to about 2% by weight.

12. A method in accordance with Claim 1 wherein the contacting of said mixture of aromatic hydrocarbons and paraffinic hydrocarbons with said oxidation system is carried out by introducing said oxidation system directly into said mixture of aromatic hydrocarbons and paraffinic hydrocarbons while vigorously agitating the resulting admixture.

13. A method in accordance with Claim 1 wherein the contacting of said mixture of aromatic hydrocarbons and paraffinic hydrocarbons with said oxidation system is carried out by countercurrently flowing a stream of said mixture of aromatic hydrocarbons and paraffinic hydrocarbons with respect to a stream containing said oxidation system.

14. A method in accordance with Claim 13 wherein the countercurrent contact of said mixture of aromatic hydrocarbons and paraffinic hydrocarbons with said oxidation system is carried out in the presence of a porous, permeable mass of inert solid contact material.

15. A method of removing aromatic hydrocarbons from a mixture of aromatic hydrocarbons and paraffinic hydrocarbons, said aromatic hydrocarbons being present in said mixture in a minor amount up to about 5% by weight which comprises contacting said mixture with an oxidation system consisting essentially of ruthenium dioxide and an aqueous hypochlorite solution, the contacting being carried out under conditions such that the mixture of aromatic hydrocarbons and paraffinic hydrocarbons is brought into intimate contact with the oxidation system with resulting selective oxidation of the aromatic hydro-carbons to carbon dioxide and/or water-soluble oxygenated aromatic hydrocarbons, the contacting operation being carried out at substantially ambient pressure and at a temperature in the range from about 10°C. to about 75%C., withdrawing the resulting reaction admixture comprising paraffinic hydrocarbons and depleted oxidation system, said depleted oxidation system comprising ruthenium dioxide and aqueous sodium chloride solution, separating the withdrawn reaction admixture into a paraffinic hydrocarbon phase and an aqueous phase containing solid ruthenium dioxide and sodium chloride dissolved therein, recovering the separated paraffinic hydrocarbon phase now substantially free of aromatic hydrocarbons, separating the ruthenium dioxide from the aqueous phase and recycling the separated ruthenium dioxide for contact with additional mixture of aromatic hydrocarbons and paraffinic hydrocarbons in the presence of added aqueous hypochlorite solution.

16. A method in accordance with Claim 15 wherein said aqueous hypochlorite solution contains sodium hypochlorite.

17. A method in accordance with Claim 16 wherein said sodium hypochlorite is present in said aqueous hypo-chlorite solution in an amount in the range from about 1.0 to about 15% by weight.

18. A method in accordance with Claim 15 wherein said aqueous hypochlorite solution has a pH in the range from about 5 to about 11.

19. A method in accordance with Claim 1 wherein said mixture of aromatic hydrocarbons and paraffinic hydro-carbons is a liquid mixture of normally liquid paraffinic and normally liquid aromatic hydrocarbons and wherein the paraffinic hydrocarbons in said mixture are n-paraffins in the range from about C6 to about C23.

20. A method in accordance with Claim 15 wherein the contacting of said mixture of aromatic hydrocarbons and paraffinic hydrocarbons is carried out at a temperature such that said aromatic hydrocarbons and paraffinic hydrocarbons are maintained in the liquid phase.

21. A method of removing aromatic hydrocarbons from a mixture of aromatic hydrocarbons and saturated aliphatic hydrocarbons which comprises contacting said mixture of aromatic and saturated aliphatic hydrocarbons with an oxidizing system comprising a ruthenium compound and an aqueous oxyhalide solution, the combination of the ruthenium compound and the oxyhalide solution reacting to yield a higher oxidation state ruthenium species, the contacting of the mixture of aromatic and saturated aliphatic hydrocarbons with the resulting generated higher oxidation state ruthenium species serving to selectively oxidize the aromatic hydrocarbons to carbon dioxide and/or water-soluble oxygenated aromatic hydrocarbons and separating from the resulting reaction admixture saturated aliphatic hydrocarbons having a substantially reduced aromatic hydrocarbon content in admixture therewith.