US2447794A - Hydrocarbon peroxides - Google Patents

Description

5...... Aug. 24, 194s HYDBOCARBON PEBOXIDES Philip D. Brewer, Long Beach, Calif" Union Oil Company of California,

Los CaliL, a corporation of California liner to No drawing. Application January 30, 1045, Serial No. 575.356

8 Claims. ((21.280-410) This invention relates to hydrocarbon peroxides and particularly to improvements in the method of production of hydrocarbon peroxides by the liquid phase oxidation of hydrocarbons or hydrocarbon fractions and is a contihuation-inpart of my copending application Serial No. 522,- 839 filed February 1'1, 1944.

In many oxidation processes and particularly a in liquid phase, air or oxygen-containing gas oxidation processes for the production of partial m oxidation products from hydrocarbon feeds the presence of peroxides in the oxidate has been observed. However, in general the peroxide content of the oxidate reaches a maximum of between about 0.5% to about 5.0% by weight of the charge, depending upon the conditions of oxidation and upon the stock and then decreases rapidly as the oxidation proceeds. In those cases in which peroxides are the desired oxidation products the oxidation is discontinued when the peroxide content has reached a maximum and the peroxides are then separated from the oxidate by various physical or chemical means to produce a useable peroxide concentrate.

It is an object of my invention to provide a method for the controlled liquid phase oxidation of hydrocarbons to produce a substantial proportion of hydrocarbon peroxides.

It is another object o! my invention to provide a method for the production of hydrocarbon peroxides involving contacting said hydrocarbon with a gas containing free oxygen in thepresence of a basically reacting agent, which agent form's salts with acids produced during the oxidation.

It is a further object of my invention to provide a new and improved method for the production of hydrocarbon peroxides by a process involving contacting said hydrocarbon with an oxygen-containing gas in the presence of a metal of the alkaline earth group, or a basic compound 40 of one of these metals, whereby the proportion of peroxides in the oxidate is-substantially increased over that proportion obtained without the use of said metal or basic metal compound.

2 vide a method for the production of a hydrocarbon oxidate containing substantial proportions of hydrocarbon peroxides which has value, without the iurther concentration of said peroxides,

as an improver for Diesel .fuel in order to increase cetane value thereof.

The invention resides in oxidizing a hydrocarbon or a hydrocarbon fraction in the liquid phase in the presence of an amount of a basically reacting agent aufflcient to react with substantially allof the form salts.

presence of ide content acids formed during the oxidation to Y rryi g out my oxidation in the a basically reacting agent the peroxof the resulting oxidate may be substantially greater than that obtainable by, oxidizing in the absence of such agents.

1 have iound, for example, that by air blowing an Edeleanu treated kerosene at ordinary atmospheric pressures and at a temperature of about 250 F, in the presence of about 3.0% by weight or powdered magnesium. oxide that I may produce an oxidate having 25.0% by weight of peroxides after 18 hours of oxidation. On oxidizing a portion of the same kerosene without the use of magnesium oxide or other basic compound the peroxide content increases to about 1.5% to about 5.0%

. rapidly.

after 10,hours and then decreases Thus, it is possible by my process to produce a hydrocarbonaceous material containing relatively high proportions, i. e. up to 25% or 30% by weight or even higher of peroxides without employing a concentrating step such as is usually necessitated when peroxide concentrates are desired.

The iunctiouv of the basically reacting agent is to react with and thus form salts with the acids which are normally formed along with the peroxides in the oxidation process. These acids may include the low molecular weight fatty acids such as formic, acetic, propionic and butyric acid as well as possibly some of the higher molecular weight carboxylic acids.

By removing these strong acids the rate of decomposition of the peroxides w hich are formed is decreased for it is It is a further object of my invention to pro- 5 known that strong acids, both mineral. acids and titration.

organic acids. cause the rapid decomposition of peroxides particularly at the temperatures employed in liquid phase oxidation processes. By

' converting the acids to salts, which salts apparently do not catalyze the decomposition of peroxides, it is possible to carry on the oxida-- tion for-longer periods of time before the rate of decomposition of peroxides exceeds their rate of formation. Thus, by my process I am able to produce, by the liquid phase air or oxygen-contaming gas oxidation of petroleum fractions,

peroxide-containing oxidates having unusually "tacting employed for in some instances peroxide oxidates have been produced by my process which have relatively high peroxide contents and yet have appreciable acid contents as indicated by In such instances the acidic bodies are apparently high molecular weight weakly acidic compounds which do not influence to any great extent the decomposition of peroxides.

While I believe the above theory of the effect of my basically reacting agents is correct I do not wish to be bound by this theory. In selecting a basically reacting agent it is important that the agent does not reduce the rate of formation of peroxides and it i highly desirable that it does not increase the rate of formation of acids under the condition of oxidation employed.

Basicallyreacting agents which I have found to be of particular value in my process include the alkaline earth metals, calcium. magnesium, strontium and barium and the oxides, hydroxides and carbonates of these metals: the basically reacting oxides. hydroxides, and carbonates of the metals of the. iron group which metals include iron, cobalt and nickel; thebasically reacting 1 oxides. hydroxides and carbonates of the metals of the right-hand column of group II of the periodic table which are not classifiable as alkaline earth metals, which metals include beryllium, zinc, cadmium and mercury;-and the oxides. hydroxides. carbonates and bicarbonates of the alkali metals sodium. potassium and lithium.

In employing these basically reacting agents. I may use them in finely divided form. such as in the form of a powder, or those which are water-soluble may be used in the form of a dilute aqueous solution. The owdered compounds may be made into a slurry or otherwise suspended in the hydrocarbon fraction being oxidized and the suspension maintained by means of mechanical agitation and/or by means of air. or other oxy gen-containing gas. agitation during the oxidation process. In a batch operation sumclent oi the basically reacting agent may be added at the start of the oxidation .to completely neutralize all of the acids formed during the processor a portion of the required agent may be added and sumcient additional quantities added during the progress of the oxidation to completely neutralize the acids formed. In a continuous operation,

I ing agents, an aqueous solution of the agent may 4 tity of basically reacting agent with the hydrocarbon feed to the oxidizer.

When employing water-soluble basically reactbe iniected into the oxidation unit with the feed, with the air or oxidizing gas or at any other convenient point. Thus, a saturated aqueous solution of calcium hydroxide or a solution of calcium hydroxide containing an excess of calcium hydroxide may be inlected into the oxidation vessel in suilicient quantities to neutralize the acids formed. Aqueous solutions ofalkali metal carbonates. bicarbonates or hydroxides may be similarly employed.

In using the alkaline earth metal themselves it is convenient to us metal turnings or shavings. supporting them on trays or racks within the oxidation vessel. As a modification of the above processes, metals and other agents described which are not appreciably water-soluble may be employed in the form of shavings or granules of any convenient size in a secondary vessel outside of the oxidation vessel and the neutralization of acids eflfected by continuously pumping the hydrocarbon being oxidized from the oxidation vessel to the secondary vessel where it is contacted by the basically reacting agent and then returned to the oxidizer.

The amount of basically reacting agent to be employed will usually be between about 0.5% and about 5.0% by weight based on the hydrocarbon feed, however it is a desirable feature that sumcient of the basic material be employed so that unreacted agent is present in the oxidate or is in a secondary vessel, as indicated hereabove, at all-times.

Oxidation stocks which may be employed include substantially all normally non-gaseous hydrocarbons or normally non-gaseous fractions of petroleum which are substantially free from asphaltic bodies and which contain less than about 5% to 10% by weight of aromatic hydrocarbons. Thus I may employ light naphthas. gasolines, kerosenes. gas 01] fractions, lubricating oil fractions, 'parafiln wax, residual oils and petrolatum or micro crystalline petroleum wax. when petroleum fractions are employed it is preferable that they be first treated with acid or with a selective solvent to remove the more aromatic and/or highly oleflnic hydrocarbons and asphaltic bodies. In addition to the various fractions indicated} may use pure hydrocarbons or relatively narrow boiling hydrocarbon fractions which may be substantially pure hydrocarbons. Thus, I may oxidize any naphthene or paraflin or monoolefin hydrocarbon or narrow boiling fractions comprising these types of hydrocarbons in substantially pure form.

The choice of feed stock will depend upon the character of peroxides desired and upon how the peroxides areito be used. Thus, when it is desired to produce a peroxide-containing fraction which is to be added to Diesel engine fuel it is desirable to employ as oxidation feed a fraction boiling within the boiling range of the Diesel fuel. Thus. a heavy naphtha, a kerosene or a light gas oil fraction is preferably employed in this case. If the peroxides are to be used as accelerators or initiators in an oxidation process, such as in the oxidation of paraflln wax it is preferable to employ paramn wax as the feed in the peroxide oxidation process.

In carrying out my partial oxidation process for the production of substantial proportions of it is generally preferable to mix the total quanhydrocarbon peroxides the hydrocarbon or bydrocarbon fraction .to be oxidized is placed in an oxidation vessel together with a part or all oi the metal or basic compound or agent to be employed and blown with air or other gas containing free oxygen until the desired peroxide con=- tent has been obtained. The oxidation, is preferably eflected at temperatures within the range of about 200 F. to about 275 52, about250 F. being a particularly desirable temperature, although I may oxidize at temperatures as low as about 175 F. and as high as about 325 F. The pressure to be employed will depend upon the stock and upon the other conditions ct oxidation employed, such as temperature, air-blowing rate, etc.. but may vary from ordinary atmospheric pressure or evenreduced pressures up to any practical pressure limit such as 300 to 500 atmospheres pressure. Normally I prefer to operate at ordinary atmospheric pressure or at pressures up gage. In those instances in which only part or the total metal or basic compound required is added at the start of the oxidation, additional quantities are introduced into the oxidation vessel as the run progresses. taking care to maintain an excess of the free metal .or basic compound at all times.

Although the process described above is a batch operation it is within the scope 0! my invention to effect the oxidation in a continuous man- .3

ner. Thus, the oxidation stock and the desired quantity or metal or basic compound may be added continuously to the oxidizer and the oxidate may be removed from the oxidizer in a continuous manner. Alternatively, the hydrocarbon feed may be introduced continuously into an oxidation chamber containing a relatively large amount of an agent, such as magnesium in the form of tumings, and further quantities of the agent may be introduced at intervals during the operation. The amount or oxidate removed from the oxidizer in such operations is so adjusted that an approximately constant liquid level is maintained within the vessel.

In those instances in which aqueous solutions of the basically reacting agent are employed the aqueous solution may be introduced into the oxidation vessel at such a'rate that an excess of the agent is present at all times. The partially spent aqueous solution is withdrawn from the bottom of the vessel together with the oxidate and may be separated therefrom by settling and decantation.

The oxidation may be efliected in the absence of initiators and/ or catalysts although I may preter to adc. to the oxidation feed a small proportion oi an oxidate from a previous operation. The peroxides present in the oxidate appear to reduce the induction period and thus effectively reducethe time required to reach a desirable peroxide content in the oxidate.

In preparing an oxidate containing substantial proportions of hydrocarbon peroxides for use in Diesel fuels, or as oxidation initiators, accelerators, or the like, the oxidate obtained in the above described manner may be washed with a dilute aqueous alkali, such as about a 2% to about a NaOH solution, or about a 5% to about solution 0! sodium or potassium carbonate to remove any acidic bodies contained in the oxidate and then washed with water and finally dried by ,settling or other means. In this manner, a product containing about 5% to about by weight of peroxides in a hydrocarbon menstruum is obto .about 100 pounds .per square inch 0 treated iuel.

tained which is substantially free from organic acidity.

In preparing a high quality Diesel engine fuel I may blend a Dieseltuel of substantially any quality with about 1% my peroxide oxidate. By adding the peroxide oxidate to Diesel fuel it is possible to increase the cetane number of the fuel up to about fifteen to twenty points above the cetane value of the un- Cetane number relates to the interval between the instant of fuel injection and the instant of ignition oi the'iuel in the combustion chamber of an engine and is described in the 1943 issue of the A. S. T. M. Standards on Petroleum Products and Lubricants prepared by A. S. T. M. Committee D-2 on Petroleum Products and Lubricants, page 172. Thus, a 45 octane num.- ber Diesel fuel may be increased to a 60 octane number iuel by the addition oi 16.0% by weight of a kerosene peroxide oxldate containing 20%- by weight of peroxides.

The rollowing specific examples will serve to further illustrate my invention:

Example I To 1700 grams of kerosene having a distillation range of 344 F. to 571 F., a gravity of 435 A. P. I. and comprising substantially equal proportions of naphthene and paraflln hydrocarbons was added 3.4 grams of powdered magnesium oxide and the mixture placed in an oxidation ves so] where it was blown with air at the rate of 2.5 cubic feet per minute per barrel of charge at a temperature of 250 F. under normal atmospheric pressure. Additional 1.7-gram increments of magnesium oxide were added every two hours and the run was continued for a total of 29 hours. A total 0127.2 grams or 1.6% by weight of magnesium oxide was employed. The peroxide content ot the oxidate as determined at various intervals during the run was: I

. Per Cent The peroxide content was determined by titration with titanium chloride according to the method described by Morrell et 9.1., Industrial Engineering Chemistry, vol. 26, page 655 (1934).

In order to show the effect of the absence of the basically reacting agent, a 2000 gram portion of kerosene oi the same character as that used above was air blown at atmospheric pressure and at 250 F. for a period of 15 hours. Test data on samples withdrawn at various intervals during the progress of the run were as follows:

Per Cent Weight 4 o Peroxidcs to about by weight oi,

Peroxides 1.- Z'xample II To 1900 grams oi kerosene o the character employed above was added 19 grams of magnesium oxide. The oxidation was eiiected under the conditions or temperature, pressure and air blowing rate employed in Example I and after six hours an additional 1% by weight of magnesium a blowingwithairatarateotflcubicieetller oxide tests and acid number determinations on samples or the oxidate withdrawn from the oxidizer at various intervals oxide was added. The oxidation was continued v oxidation 'mafloum: for a total or 22 hours and during this time a tom tal of 57 grams or 3% by weight of magnesium cm oxide had been employed. Samples removed for b -ggg. analysis as the run progressed were analysed ior 5? m peroxide content with the following results: Peroxides x0 g V 8 L cm 10 111: t Hours w ht 11 no u. I 14 12.0 17. Peroxides 18 as so. a s o 20 g 22 Example V 7 1s aa'o To 1900 grams oi kerosene was added 19 Q 26 rams or 1% by weight of calcium carbonate and this mixture was air blown at 250 1". under nor- A 1,000 gram portion of the oxidate containing 20.1 by weight of the peroxides was washed with two 100 ml. portions of aqueous potassium carbonate solution containing 15% by weight of K200: and then washed with water to remove any potassium carbonate remaining in the oxidate. The washed product was allowed to settle until clear and there was recovered 950 grams of a peroxide oxidate containing 18.0% by weight of peroxides. A 120 grain portion of this washed oxidate was added to and thoroughly mixed with 1,000 grams or a Diesel fuel having a cetane number of 47.5 and the resulting blend had a cetane number of 58.0.

Example In To 60,000 grams oi kerosene was added 1,200 grams or 2% by weight or magnesium oxide and this mixture was air blown using an air rate of 2.5 cubic feet per minute per barrel of charge at 250 F. to 275 F. at a pressure oi 95 pounds per square inch gage. The oxidation was continued for a total of thirteen hours without further additions of magnesium oxide. The results of peroxide tests on samples withdrawn at various intervals during the oxidation were as follows:

Per Cent Hours We ht Perorldes The final product containing 20.9% by weight of peroxides had an acid number of 9.5 mg. KOH/g.

Example IV A 1700 gram portion of kerosene was oxidized in the presence or 51 grams of 3% by weight or magnesium turnings. The oxidation was elected at 250 F. under normal atmospheric pressure by Per Cent Hours We t I Perci r les s z s: a:

' Example Vi To 2000 grams or paramn wax having a melting point or 1". to F. was added 60 grams or 3.0% by weight or magnesium oxide and the mixture was air blown at 250 1". for a period of 25 hours at normal atmospheric pressure using an air rate of 2.5;ciibic feet per minute per barrel oi charge. Samples of the wax were withdrawn from the oxidizerat various intervals during the oxidation and analyzed for peroxide and acid content with the following results:

In order to show the eilect oi the absence of the basically reacting agent a 2000 gram portlon oi the same paramn wax was oxidized under the same conditions or temperature. pressure, time and blowing rate but in this case no agent was used. The results of tests on samples removed at intervals during the 25 hour period of oxidation were as follows;

Per Cent 7 Weight oi Peroxides Hours about 300 F. at pressures sumcient to maintain said liquid phase in the presence oi an amount of from 0.5 to 5.0% by weight of a basically reacting compound of an alkaline earth metal maintaining at all times the presence of the basically reacting agent to an acid number not exceeding about 21 mg. KOH/g. to produce an oxidate containing between about and about 30% oi said paraffin hydrocarbon peroxide and separating the partially spent basically reacting agent from the oxidate.

2. A process for the production of a paraflln hydrocarbon peroxide concentrate containing between about 5% and about 30% by weight of paraffin hydrocarbon peroxides which comprises air blowing normally non-gaseous paraflin hydrocarbon iraction in the liquid phase at temperatures between about 225 1". and about 300 'F.

and at pressures suiiicient to maintain said liquid phase in the presence of an amount or from 0.5 to 5.0% by weight of a basically reacting com- 5 pound of an alkaline earth metal maintaining at 0 Number all times the presence of the basically reacting agent to an acid number not exceeding about 21 mg. KOH/g. and subsequently separating the resulting oxidate from the partially spent basically reacting agent.

3. A process as in claim 2 in which said basically reacting agent is an alkaline earth metal oxide.

4. A process as in claim 2 in which said basically reacting agent is a carbonate.

5. A process as in claim 2 in which said basically reacting agent is magnesium oxide.

6. A process as in claim 2 in which said basically reacting agent is calcium carbonate.

7. A process as in claim 2 wherein said normally non-gaseous paraflln hydrocarbon fraction is a petroleum fraction having a distillation range of irom about 344 F. to about 571 F.

8. A process as in claim 2 wherein said normally non-gaseous paraflln hydrocarbon fraction is paraflln wax.

PHILIP D. BREWER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Hartmann Aug. 29, 1933 Friedolsheim Nov. 20, 1934 Penniman Mar. 26, 1935 FOREIGN PATENTS Country Date Germany Jan. 2, 1922 Great Britain Mar. 31, 1922 Number