US1992309A

US1992309A - Oxidation of hydrocarbons

Info

Publication number: US1992309A
Application number: US448801A
Authority: US
Inventors: Edgar W Hultman
Original assignee: HULTMAN AND POWELL CORP
Current assignee: HULTMAN AND POWELL CORP
Priority date: 1930-04-30
Filing date: 1930-04-30
Publication date: 1935-02-26
Anticipated expiration: 1952-02-26

Description

Feb. 26, 1935.

E. w. HULTMAN OXIDATION 0F HYDROCARBONS originai Filed Aprii so; 19:50

Patented Feb. '26, 1935 UNlTED STATES PATENT OFFICE K OXIDATION 0F HYDBOCABBONS Edgar W. lultman, Los Angeles, Calif., assigner to Hultman and Powell Corp., corporation of Delaware never, nel., a

Application April 3o, 1930, serai No. 448,801

Renewed October 26, 1934 12 claims.

' oxidation compounds. 'Ihe oxidation compounds of the hydrocarbons are generally soluble, to a considerable extent at least, in the electrolyte and can be separated therefrom by a suitable method, for example fractional distillation, after which the electrolyte, after suitable dilution if deslired, can again be oxidized in the electrolytic ce l In a copending application 390,657 filed September 5, 1929, I have described a process of reining petroleum products including gasoline and various others. by treating with an electrolytically oxidized refining agent consisting for example of dilute sulphur-ic acid of 35 to 80 per cent, and preferably around 50 per cent strength.

In the present process I also use such an electro-v lyte which is oxidized electrolytically, and contacted with the liquid oil or petroleum distillate, the contacting preferably being effected very shortly after the formation of the oxidized sulphuric acid.

The oxidation of the sulphuric acid may be lperformed by passing a direct current of electricity through sulphuric acid of say 50 per cent,

.although the strength may vary between about 30 per cent and about 80 per cent, the object of the electrolysis being to form considerable quantities of oxidation products of sulphuric acid, such as persulphuric acid, Caros acid, and hydrogen peroxide. Ozone or oxygen may also be produced to a considerable extent.

The oxidation of the electrolyte may conveniently be performed in a cell having a platinum anode, and a lead cathode, separated by a suitable ceramic diaphragm, thelatter may be in the shape of an inverted bowl, and the platinum anode may be water-cooled, for example it may consist of a coil of platinum tubing lthrough which cooling water is causedf to flow. The cathy ode may be a strip of lead or a lead cup, in the outer compartment of the cell surrounding the -bowl above referred to.

From the anode compartment, which thus may consist of the inverted bowl a smallopen tube leads upwardly into a superposed receptacle containing the hydrocarbon liquid to be treated.

The oxidized electrolyte from the anode 'compartment ofthe electrolytic cell passes up through this tube bubbling into the hydrocarbon, and at once reacts vigorously therewith giving the hydrocarbon the appearance'of boiling', and bubblesof gas being formed and escaping from the said oil. The alcohol produced in the oil by such oxidation, as well as the aldehydes andfatty acids mostly dissolve in the acid electrolyte and the exhausted electrolyte carrying the organic oxidation products in solution, settles to the bottom of the oil receptable, being drawn of! again 'into the outer compartment of the electrolytic cell. 'I'his operation is continued until itis found that a desired amount of oxidation has been performed, when the electrolyte may contain say 5 to 10% of dissolved oxidation products oi the oil, and the, electrolyte can then be passed to a still and the alco-` hol, aldehyde and fatty acids distilled off, during which operation of course a good deall of the water content of the electrolyte would also distill on, and the sulphuric acid can then be diluted to about 50 per cent and cooled and againintroduced into the electrolytic cell. If desired a portion of theelectrolyte can be continuously drawn off, distilled to recover the oxidation products of the hydrocarbon, diluted, cooled and again continuously reintroduced into the electrolytic cell. 'I'his mode of separation is given by way or example, and any suitable mode of separation can be employed.

The processcan be continued until as much as half of the body of hydrocarbon has been converted into oxidation products. v

The temperature of the liquid in the electrolytic cell is preferably kept down, for example by the cooling water in the tubular anode or in any other suitable manner, preferably to as low as 60 F., or lower. The lower the temperature of the eleotrolyte the morel stable is the persulphuric acid land other oxidation products of the electrolyte.

The hydrocarbon liqui'd inv the treating receptacle should b'e kept cool enough to prevent excessive amounts of vaporization of the same, this material may bey at about ordinary room tempossible to produce alcohols containing more than two OH groups.

Without restricting the invention to details, it is stated that the voltage may be at about 7 to 17, at 5 to 15 amperes. In a particular case 18 volts at 10 amperes gave very satisfactory results. y

This corresponded .to about amperes per ,square decimeter of anode area, and the ratio of cathode surface to anode surface was about 15:1. Without restricting the invention to details, the following examples of the process are given.

Example 1 A straight run (uncracked) petroleum ether boiling between 40 and '70 C. constituted the starting material. This consisted largely of pentane, hexane and heptane, and was substantially free from unsaturated hydrocarbons and was also substantially free from sulphur. The liquid was .put into the flask above described, which was positioned over the electrolytic cell with two glass tubes passing through the bottom of the flask forming the two passageways above referred to. The current was passed between the electrodes, in this case a current from a 10 volt line, at about 8 amperes was employed. The acid from theanodic compartment passed up through the vertical tube into contact with the petroleum ether, and the bubbles and flow produced gave the latter the appearance of boiling. The dilute acid'separated out from the hydrocarbon in the bottom of the. flask, and was allowed to run back into the outer compartment (cathode compartment) of the electrolytic cell, adjustment being had by a suitable valve in the said uoutlet tube. The temperature in the electrolytic cell was maintained between and 62 F., and the temperature of the petroleum ether was about 'l0 to '72 F. Alfter being allowed to run for 3 to 5 minutes the electrolyte was found Vto contain a considerable amount of alcohols, including butyl, amyl, hexyl and heptyl. After running for 10 to 15 minutes', the corresponding aldehydes were found to be present lin the electrolyte to a considerable extent, and after running for fhalf anhour it was found that the corresponding fatty acids were present in the electrolyte, the concentration of the same being about 5%.

The solution of the electrolyte was run through a still, and the organic compounds above referred to were separated from the same by distillation. The residual acid was then diluted to 50% and cooled and brought back into the electrolytic cell,

l for regeneration of the oxidizing agent.

Example 2 A cracked petroleum ether, that is to say a petroleum ether or liquid having a boiling point range of from about 40 to about '10 C., made by cracking a heavier petroleum product, was used as the starting material. The procedure was carried on as in the above example, and it was Y found that a large percentage of dihydric alco- Example 3 I Gasoline was first treated in accordance with the example of the prior application 390,657 above referred to, for the removal of sulphur. The sulphur was largely removed from the gasoline during the first four minutes of treatment. The treatment was then continued giving results similar to the above, but higher alcohols being largely produced. In some cases considerable amounts of butyric acid, together with some of the higher acids were also produced.

In some eases cracked gasoline high in oleflnes and other unsaturated compounds are found to give considerable amounts of higher glycols.

It will be understood that the process can be accelerated to some extent by the use of suitable catalytic agents, thus for example cerium sulphate can be used as a constituent of the electrolyte, along with the sulphuric acid as above described,

My tests have indicated that up to 40 or 50%,

-more or less, of the petroleum ether can be converted into the oxidized bodies, by continuing the running.

While I have referred particularly to low boiling oils, such as petroleum ether and gasoline, I call attention to the fact that the invention embraces the treatment of oils of any degree of volatility or boiling point range, such as kerosenes, motor oils, and heavier oils, and is not restricted to the lighter distillates. The invention is equally applicable whether or not the oils contain sulphur compounds or other impurities.

A highly important feature of the present invention resides in bringing the oxidized electrolyte very promptly after its formation into contact with the oil. An electrolyte which has been allowed to stand, even for a few minutes isnot nearly as effective. A mixture containing sulphuric acid and persulphuric acid, made for example by adding potassium persulphate to a largeexcess of 50% sulphuric acid is not very effective (if useful at all) for producing the results of the present process.

The process can be carried out in apparatus such as is illustrated diagrammatically in the annexed drawing, forming a part of this application. Y

A receptacle 10, which may be in the form of a large earthenware jar is provided, and this contains a plate 11 which also canv be made of earthenware, thereby forming an upper and a lower compartment. The lower compartment can be filled with sulphuric acidof the concentration referred to above. The anode may be a platinum wire or platinum foil indicated at 12, this being positioned within a glass bowl or cup 13, which has a spout projecting upwardly through a hole in the central part of the plate 11, as indicated at 14. The cathode may be a cylindrical lead cup, open at the top and bottom, as indicated at 15. Within the lower compartment, and preferably located in and around the anode cup 13 is a refrigerating coil 16, for maintaining the liquid in and near the cathode compartment at a low temperature, for example at 60 C. or lower.

The-receptacle 10 is first illled with electrolyte up `to about the level 17, after which the apparatus is filled with the hydrocarbon oil to be treated, say up to the level 18. A direct current is then passed in from the lead 19 to the anode 12, the cathode l5 being connected to the lead 20. When the current of electricity is passed, hxdrogen s given oli' at the cathode, which nds its exit through the pipe 21, and can be suitably utilized. Water or very dilute sulphuric a'cid is added from time to time, through the pipe 22, for maintaining the acid level at 17, and a portion of the electrolyte. will ilow upwardly through the passage 14, and will cause considerable stirring in the oil,

oxidizing the oil as indicated above, the spent .f will thereby assist the ilow of the electrolyte from the compartment 13 into the oil, whereby the said electrolyte is brought into contact with the oil very soon after formation ci' the electrolyte, and without allowing such decomposition of the electrolyte as would take place on standing for a protracted period.

I claimtf 1. A process of producing exidation products from hydrocarbons which comprises oxidizing .sulphuric acid by electrolytic oxidation to iorm a carbons, such bringing together of said materials being effected promptly after the production oi said oxidation products, 4and continuing the treatment until the aqueous acid liquid contains the desired products of oxidation of said hyrocarbons, in a substantial amount.

3. A process which comprises circulating a dilute sulphuric acid electrolyte containing about 30 to 80% of H2804, through an electrolytic cell and bringing the anodic oxidation product at once into contact with a petroleum hydrocarbon, and continuing such treatment until said electrolyte has accumulated a substantial amount of oxidation products of said hydrocarbon, separating the oxidation products -oi the hydrocarbon from the sulphuric acid and reintroducing the latter, as dilute acid, into said cycle. 4. A process which comprises circulating a dilute sulphuric acid electrolyte through an electrolytic cell and bringing the anodic oxidation products at once into contact with a petroleum hydrocarbon not substantially more volatile than gasoline, and continuing such treatment until said electrolyte has accumulated a substantial amount of oxidation products of said hydrocarbon, separating the oxidation products of the hydrocarbon from the sulphuric acid and reintroducing the latter, as dilute acid into said cycle.

5. A process which comprises circulating a dilute sulphuric acid electrolyte through an electrolytic cell and then at once into contact with a hydrocarbon consistingy largely of petroleum ether, and continuing such treatment until san` electrolyte has accumulated a substantial amount of oxidation products of said hydrocarbon, separating the oxidation products of the hydrocarbon from the sulphuric acid and reintroducing the latter, as dilute acid into said cycle.

6. A process which comprises circulating a dilute sulphuric acid of about 30 to 80% strength, Ipreferably around 50% strength through an electrolytic cell and bringing the anodlc oxidation products at once into contact with an open chain hydrocarbon, and continuing such treatment until said electrolyte has accumulated a substantial amount of oxidation products of said hydrocarbon, separating the oxidation products of the hydrocarbon iromthe sulphuric acid and reintroduclng the latter, as dilute acid into the saidl 1 cycle.

'7. A process of electrolytically oxidizing yan electrolyte containing dilute sulphuric acid in an electrolytic cell, surmounted by a treating receptacle at'only a short distance therefrom, passing the oxidation product of such electrolysis upward directly into said treating receptacle into contact with a low-boiling petroleum fraction, whereby the latter becomes oxidized and taken up to some lextent at least by the acid, and thereafter re' continuing such treatment until said electrolytev has accumulated a substantial amount 'of oxidation products of said hydrocarbon, separating the oxidation products of the hydrocarbon from the sulphuric acid and reintroducing the latter, as

ldilute acid into said cycle.

9. A process which comprises circulating a dilute sulphuric acid electrolyte through an elec trolytic cell under conditions capable of oxidizing the same and into contact with a petroleum fraction less volatile than kerosene, and continuing such treatment until said electrolyte has accumulated a substantial amount of oxidation products of said hydrocarbon, separating the oxidation products of the hydrocarbon from the sulphuric lacid and reintroducing the latter, as dilute acid into said cycle.

i 10. A process which comprises circulating a dilute sulphuric acid electrolyte through an electrolyticl cell capable of oxidizing such acid and then in contact with a hydrocarbon consisting largely oi petroleum ether, and continuing such treatment until said electrolyte has` accumulated a substantial amount of oxidation products oi said hydrocarbon, separating the oxidation products ,oi the hydrocarbon from the sulphuric acid by distillation and reintroducing the latter, as dilute acid into said cycle.

11. A process which comprises circulating a lute sulphuric acid electrolyte containing about 30 to 80% of H2SO4, through an electrolytic cell and bringing the anodic oxidation product at once into contact with a petroleum hydrocarbon, and 5 continuing such treatment until said electrolyte has accumulated a substantial amount of oxidation products of said hydrocarbon containing at least one of the herein described group consist,-

ng of alcohol, aldehyde and fatty acid, s'aparat- 1 ing such oxidation products of hydrocarbon from the sulphuric acid and rentroducns;r the latter, as dilute acid, into said cycle.

EDGAR W. HULTMAN.