US2129193A

US2129193A - Motor fuel

Info

Publication number: US2129193A
Application number: US42510A
Authority: US
Inventors: Arthur L Blount; Estates Palos Verdes; Harold G Reiber
Original assignee: Union Oil Company of California
Current assignee: Union Oil Company of California
Priority date: 1935-09-27
Filing date: 1935-09-27
Publication date: 1938-09-06
Anticipated expiration: 1955-09-06

Description

Patented Sept. e, was

PATENT OFFICE MOTOR FUEL Arthur L. Blount, Palos Verdes Estates, and Barold G. Reiber, Long Beach, (Jalii'.I asslgnors to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing.

Application September 27, 1985,

Serial N0. 42,510

18 Claims.

The present invention relates to a process and means for improving low boiling hydrocarbon fractions, especially hydrocarbon-containing motor fuels such as gasoline, kerosene, motor benzol, or the like.

It is common knowledge that liquid hydrocarbon fuels produced on a commercial scale, and particularly those obtained from various crude petroleurn oils by any of the well known processes of distillation, cracking or solvent extraction, contain gum or gum-forming constituents which are objectionable in many respects. Thesame may be said about motor benzol which is a hydrocarbon fuel derived from coal-tar and which contains a large percentage of aromatic and unsaturated hydrocarbons. Gum or gum-forming tendencies of naphtha. gasolines, and similar lowboiling hydrocarbon fractions is determined by the method No. 530.1 in the United States Bureau of Mines Technical Paper 3233, page 96. entitled "Specification for Petroleum Products and Methods of Testing", revised October 21, 1927. In brief. this method consists in placing 100 c. c. of the liquid hydrocarbon to be tested in a spun copper dish about three and one-half inches in diameter on a steam bath, and evaporating oil the volatile material. The result is expressed as milligrams of gum left in the dish per 100 c. c. of gasoline, naphtha or similar low boiling fractions.

The presence of gum-forming constituents is especially pronounced in the case of gasoline produced by any of the well known cracking processes. Although such gasolines constitute excellent motor fuels from an anti-knock standpoint, they are objectionable in view of the fact that they contain or develop large amounts of gum on storage, and /or tend to deposit gum in various parts of an internal combustion engine, thus interfering with its eiijcient operation. They are likewise quite unstable with respect to color and darken even on standing for a few days.

It has been customary to chemically refine gasolines, naphthas and other hydrocarbon-containing motor fuels to remove the highly unsaturated compounds present therein which are responsible for the above mentioned gum formation. Although by such treatment an improved motor fuel may be obtained from the standpoint of gum formation and/or deposition, the antiknock value thereof is generally considerably impaired because such chemical treatments not only remove the highly unsaturated bodies deemed responsible for the production of gums but also remove hydrocarbons of a lesser degree of unsaturated and aromatic compounds which con- 'stitute the desirable anti-knock constituents of the motor fuel.

The presence of unsaturated hydrocarbons even those of the type responsible for the formation of gums or gummy products is not undesirable and would even be beneficial were it not for the fact that in the presence of air or oxygen during storage or use, they tend to absorb oxygen with the formation of the above mentioned undesirable products, thereby impairing the value and usefulness of the motor fuel.

On account of this, a producer of hydrocarboncontalning motor fuels which contain unsaturated compounds is continuously confronted with the problem of gum formation.

Hence, it is an object of our invention to produce high grade motor fuels having no or a substantially reduced gum-forming tendency and which do not exhibit any tendency to become discolored on standing.

It is another object of our invention to present a series of compounds which, when added to hydrocarbon-containing motor fuels which normally tend to form gums during the usual conditions of storage, inhibit or substantially reduce such gum-forming tendencies, and render them more stable with respect to color.

Other objects will be apparent from the description of our invention given hereinafter.

According to our invention, the usual chemical purification processes which, as previously stated, tend to remove certain desirable fractions from various motor fuels, may be substantially reduced in intensity or may even be entirely eliminated Without danger of presenting an inferior quality motor fuel. By adding suitable amounts of the compounds described below, to a motor fuel, it is possible to obtain one containing all the desirable components including unsaturated hydrocarbons without having to consider the possibility of gum formation therein during the usual periods or conditions of storage or use.

We have discovered that certain organic compounds containing arsenic, if added to any of the motor fuels set forth above, inhibit the formation of gum or reduce the quantity thereof as determined by the previously described copper dish test or by any other test commonly employed for detecting gums. Their presence in a motor fuel will also tend to stabilize the color thereof as explained hereinafter.

The organic compounds of arsenic, which we have found to constitute excellent inhibitors or retarders for gum formation in hydrocarbon-containing motor fuels which, in the absence of these compounds, tend to form substantial amounts of gum, are compounds of the type:

As-R aryl or alkoxy-aryl arsine with an aliphatic aldehyde. Specific compounds falling within the above identified class are: tetrahydro-Zi, 6-dimethyl-2, 5-diphenyl-1, 4, 2, 5-dioxdiarsine,

o--on'cn.

HaC- C-O tetrahydro-li, 0-dimethyl-2, 5-ditolyl-1, 4, 2, 5- dioxdiarsine.

o--ca-om cal-cams summons tetrahydro-3, 8 dimethyl 2, 5 di p-ethoxy phenyl-l, 4, 2, 5-diozdiarsine,

o-oa-om CJHIOOM AsCsHcOCsHs.

Likewise, suitable amounts of mixtures of any or all of the above mentioned compounds or mixtures of these and compounds of the same class but containing different aryl or alkoxy-aryl substituents may be added to the motor fuel to decrease or inhibit gum formation therein and to prevent them from becoming discolored on standing.

Other compounds which we have found to substantially retard or inhibit the formation of gums in hydrocarbon-containing motor fuels are those obtained by condensing an aromatic aldehyde with a primary arsine. These compounds have the general formula: R-As-(CHOHR): wherein R is an aryl or alkoxy-aryl group. Compounds falling within this group and which excellent gum inhibiting tendencies are: bism-hydroxybenzyl) phenylarsine CsHsA8(CHOHCsHs) a; bis(-s-hydromolyl) tolylarsine HsCCeHiAS (CHOHCeHsCHa) s and his a -hydroxybenzyl) ptolyl arsine CHsCsHe-As-(CHOHCsHs) I.

Mixtures of any or all of the above as well as mixtures of any or all of these and one or more of the compounds of the type o-onm BAs As1l hydrocarbon fuels into which they are introduced and will continue their stabilizing action for days and even months. Their presence in a hydrocarbon-containing fuel will prevent the absorption of oxygen by certain of the more unsaturated compounds present which absorption if not inhibited results in the formation of gums or gummy products. This gum formation is a cataiytic process 1. e. the rate of the formation of gums is catalyzed by those gums already present.

The quantity of the material added to the motor fuels for inhibiting the formation of gums may be very small. In general, amounts of the inhibitor varying from 0.001% to 0.1% by weight with respect to the hydrocarbon-containing motor fuel to which they are added. are insuflicient to inhibit or substantially retard any gum-forming tendency therein, although in some instances greater or smaller amounts may be added.

The method of adding our inhibitors is exceedingly simple. For example, we may dissolve a quantity of the inhibitor in a small portion of the particular fuel to which it is to be added to form a concentrated solution thereof and then add a sumcient amount of this solution to the fuel to be treated. Or, a suitable amount may be directly added to a large volume of the fuel and dissolved therein by proper agitation. In some instances it may be preferable to dissolve the inhibitor in a hydrocarbon-cobble solvent such as bensoi, absolute alcohol or ether, and add suitable amounts of this solution to the motor fuel.

The following examples are illustrative of our invention: A pressure distillate having a gravity of 522 A. P. I. and which had been given only a mild acid treatment (2% lbs. of H280. per barrel) followed by redistiilation, was found to have a copper dish gum test of 70 mgs. per 100 c. c. without addition of any inhibitor. Upon addition of 0.005% of tetrahydro-3,8-dimethyl-15-diphenyl- 1,43,5-dioxdiarsine, the gum content decreased to 21 mgs. per 100 c. c.

A second pressure distillate with a gravity of 44.7 A. P. I. and which had been subiected to a treatment with sodium plunibite had an initial copper dish gum test of 872 mgs. per 100 c. c. When 0.01% of tetrahydro-md-dimethyl-zb-diphenyl-1,4.2,5-dioxdiarsine was added to 100 c. c. of this distillate, its gum content amounted to only 88 mgs. When this same pressure distillate (100 c. c.) was treated with 0.01% of a gum inhibitor sold under the trade name Vanoline (parahydroxy diphenyl amine) its gum content was reduced to only 616 mgs. per 0. c.

The formation of gums in hydrocarbon-containing motor fuels on storage is closely associated with an increase in color intensity of the particular fuel. Our inhibitors are found not only to exert an inhibiting tendency toward gum formation even on storage over prolonged periods of time but also are responsible for the prevention of undesirable color formation. The term "inhibiting gum formation" used in the present specification and claims is meant to include the feature of color stabilization. The following example is illustrative of this feature of our invention:

A pressure distillate which had been given a slight acid treatment (2% lbs. of 11,504 per barrel) and which had been subsequently redistilled and doctor treated had an initial color of 1 N. P. A. which after storage of the distillate for a period of 14 days increased to 1% N. P. A. When adding 0.005% of tetrahydro-3,6-dimethyl- 2,5-dipheml-L42j-dioxdiarsine to a fresh c. 0. sample thereof, the color was still better than 1% N. P. A. after standing over a period of 4 months.

As previously stated, the usual chemical refining of the motor fuel, consisting of a treatment with concentrated sulfuric acid, alkali treatin the acid treated fuel and subsequently water washing may be substantially reduced in intensity or even entirely omitted. However. we prefer to subject the hydrocarbon-containing motor fuel to a treatment with sodium plumbite or an equivalent agent (to remove injurious sulfur compounds) prior to adding our inhibitors.

Although the compounds set forth herein are especially suitable for stabilizing cracked gasolines or blends of cracked and straight run gasolines with respect to the formation of gum, they may be equally well added to other hydrocarboncontaining motor fuels which contain gumforming constituents. They likewise will act as antioxidants in heavier petroleum fractions such as kerosene, gas oil, lubricating oil and the like.

Gum tests are generally conducted by the previously mentioned copper dish method, but sometimes by a similar test in which a porcelain dish is used. However, by either method of test, our process is found to reduce or inhibit gum formation.

The term N. P. A. color" used herein relates to a color grade of a liquid obtained by means of the Union Petroleum colorimeter adapted as a standard of the National Petroleum Association in 1915. A detailed description of the apparatus, method of test and significance of scale readings may be found in David T. Day--Handbook of Petroleum Ind., 1922, vol. 1, page 665."

The examples and theories set forth herein are not to be considered as limitations upon our process. As to the scope of our invention, reference is hereby made to the appended claims.

We claim:

1. In a process for inhibiting gum formation in hydrocarbon-containing motor fuels which normally develop gum during the usual conditions of storage, the step of adding thereto small amounts of an organic arsenic compound of the type wherein R is an aryl or alkoxy-aryl group, and R is an alkyl group from the class consisting of methyl, ethyl and propyl groups.

2. In a process for inhibiting gum formation in hydrocarbon-containing motor fuels which normally develop gum during the usual conditions-of storage, the step of adding thereto between 0.001 and 0.1% of an organic arsenic compound of the type wherein R is an aryl or alkoxy-aryl group, and R is a lower alkyl group.

3. In a process for inhibiting gum formation in hydrocarbon-containing motor fuels which normally develop gum during the usual conditions of storage, the step of adding thereto small amounts of tetrahydro,-3,6-dialkyl-2,5-diphenyl- 1,4,2,5,-dioxdiaraine.

4. In a process for inhibiting gum formation in hydrocarbon-containing motor fuels which normally develop gum during the usual conditions of storage, the step of adding thereto small amounts of tetrahydro, 3,6 dialkyl 2,5 ditolyl,-1,4,2,5-dioxdiarsine.

5. In a process for inhibiting gum formation in hydrocarbon-containing motor fuels which normally develop gum during usual conditions 01 storage, the step of adding thereto a very small percentage of a tetrahydro dialkyl diaryldioxdiarsine.

6. Hydrocarbon-containing motor fuels which normally develop gum during the usual conditions of storage and containing an organic arsenic compound of the type OCHR As-R wherein R is an aryl or alkoxy-aryl group from the class consisting of phenyl, tolyl, oxyphenyl and oxytolyl groups, and R is a lower alkyl group.

'7. Motor fuels containing hydrocarbons which normally develop gum during the usual conditions of storage and containing a small proportion of tetrahydro,-3,6 dialkyl 2,5 diphenyl 1,4,2,5,-dioxdiarsine.

8. Motor fuels containing hydrocarbons which normally develop gum during the usual conditions of storage and containing a small proportion of tetrahydro,-3,6-dia1kyl-2,5-di-tolyl,1,4,2,5-dioxdiarsine.

9. Motor fuels containing hydrocarbons which normally develop gum during the usual conditions of storage and containing between 0.001 and 0.1% of tetrahydro,3,6-dialkyl-2,5 diphenyl 1,42,5-

dioxdiarsine, the alkyl being taken from themethyl, ethyl and propyi groups.

10. Motor fuels containing hydrocarbons which normally develop gum during the usual conditions of storage and containing between 0.001 and 0.1% of tetrahydro,-3,6-dialkyl-2,5-di-tolyl,1,4,2,5-dioxdiarsine, the alkyl being taken from the methyl, ethyl and propyl groups.

11. Motor fuels comprising cracked gasoline containing small amounts of an organic arsenic compound of the type 0cnn R-As s-R R c-o wherein R is an aryl or alkoxy-aryl group, and R a lower alkyl group.

12. Motor fuels comprising hydrocarbons which normally develop gum during usual conditions of storage containing small quantities in the order of 0.001% to 0.1% of a tetrahydro-dialkyl-diaryldioxdiarsine.

13. A process for inhibiting gum formation in hydrocarbon-containing motor fuels which normally develop gum during the usual conditions of storage which comprise adding thereto small amounts of organic arsenic compounds of the type R-As-(CHOHR) 2 wherein R is an aryl, or alkoxyaryl group.

14. A hydrocarbon-containing motor fuel which normally develops gum under oxidizing conditions containing a small amount sufficient to inhibit such gum formation of an organic arsenic compound of the type R-As (CHOHR): wherein R is an aryl or alkoxy-aryl group.

15. A composition as defined in claim 14 wherein the compound added is bis(-a-hydroxy benzyl) phenyl arsine CtHsAS(CHOHCsHs) 2.

16. Hydrocarbon-containing motor fuels which normally develop gum during the usual conditions 4- memos of storage, containing between 0.001% and 0.1% wherein R is an aryl or aikoxy-aryl group and R or a compound of the class consisting oi. an orslower alkyl group, and an organic arsenic comganic arsenic compound of the type pound of the type R-A8(CHOHR)2 wherein R is O OHBI an aryl group. R ARTHUR BLOUNT. 5

HAROLD REIBER.

CERTIFIOATEOF CORRECTION. Potent No. 2,129,195. 7 September 6, 1958.

i ARTHUR If. BLOUNI', ET AL.

It is'hereby certified thslt error appears in the printed specification of the nbox re numberen patentrequiring correction as follows: Page 2, second colmnn, line 16, for "insufficient" read sufficient; and that the said Letters Patent shoulnbe rend. with this correction therein that the same may confer-m te the record of the case in the Patent Office.

Signed and sealed this 27th day of ecember A. D. 1958.

Henry Van Airedale (Seal) iicting Gemnissioner of Patents.

4- memos of storage, containing between 0.001% and 0.1% wherein R is an aryl or aikoxy-aryl group and R or a compound of the class consisting oi. an orslower alkyl group, and an organic arsenic comganic arsenic compound of the type pound of the type R-A8(CHOHR)2 wherein R is O OHBI an aryl group. R ARTHUR BLOUNT. 5

HAROLD REIBER.

CERTIFIOATEOF CORRECTION. Potent No. 2,129,195. 7 September 6, 1958.

i ARTHUR If. BLOUNI', ET AL.

Signed and sealed this 27th day of ecember A. D. 1958.

Henry Van Airedale (Seal) iicting Gemnissioner of Patents.