US2027394A - Treatment of hydrocarbons - Google Patents

Description

Patented Jan. 14,

UNITED STATES v 2,027,394 TREATMENT OF HYDBOCABBONS Edward W. McMullan, Philadelphia, Pa., assignor, by mesne assignments, to Gasoline Antioxidant Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 10, 1930, Serial No. 501,479

Claims.

The present invention relates to the art of stabilizing hydrocarbon oils, and has particular reference to the treatment of low boiling hydrocarbon oils such as naphtha, gasoline, and kero- 5 sene to render the same more stable, and also to the product resulting from such treatment.

Such low boiling oils even after being refined, may undergo spontaneous chemical changes upon standing which cause the formation of objectionable gum which may precipitate, causing a deposit to form, or which may remain in solution or suspension therein as a cloud or haze until the oil is vaporized, whereupon it may deposit, as for example upon motor parts or wicks.

The phenomenon of gum formation is particularly noticeable in the case of oils which result from cracking higher boiling oils. As most commercial gasolines contain distillates which result from cracking, and since in recent practice there 20 is a trend toward increasing the content of cracked distillates in gasoline, the problem of gum formation is of prime importance.

My invention is based upon the discovery that the aforesaid objectionable formation of gum in hydrocarbon oils, particularly low boiling hydrocarbon oils such as naphtha, gasoline, and kerosene, upon allowing such oils to stand for some time, and particularly when exposed to direct or diifused light, more particularly sunlight, may be materially inhibited by dissolving in the oil a small amount of certain compounds having an azo, hydrazo, or azoxy group. These compounds are characterized in that they contain two hydrocarbon radicals joined to one another through a nitrogen to nitrogen linkage. This will be seen from the following formulae in which R and R represent the hydrocarbon radicals which may be alkyl or aryl or substitute alkyl or aryl groups:

A20 compounds Hydrazo compounds R-N-N-R' Azoxy compounds RNNR' advantage. 0! the substances named I prefer to use azo benzene and/or hydrazo benzene.

The amount of these substances necessary to be added to the hydrocarbon oil in order to inhibit gum formation when the oil is allowed to 5 stand depends upon such factors as the particular oil being stabilized and the conditions to which the oil is to be exposed. These factors may be taken into consideration in determining the proper amount of gum inhibitor to be added to any 10 particular oil. In general, the amount of gum inhibitor required does not exceed 1% by weight of the oil, and in most cases the addition to the oil of an amount of the order 01 0.05% to 0.5% by weight is ample to inhibit substantial gum 15 formation.

In accordance withimy invention, a small quantity of one or a mixture of two or more of the compounds named is added to the oil, it being preferred to agitate the oil to facilitate solution 20 of the gum inhibitor therein. Although this addition may be made prior to completion of the ordinary refining processes, it is preferred to add the gum inhibitor subsequent to refining operations.

My process will be more completely understood by reference to the following examples:

Example 1 To a blended gasoline consisting of a 50--50 39 mixture of straight run gasoline with gasoline obtained by cracking the gas oil fraction of a West Texas crude oil, which by the copper dish test gave 21 mg. of gum, there was added 0.1% by weight of azo benzene. After standing 51 35 hours in direct sunlight the sample containing azo benzene had a gum value of only 28 mg. per cc. A portion of the same gasoline without azo benzene when allowed to stand for a similar period of time and under like conditions, showed 4 a gum value of 129 mg. per 100 cc. After 151 hours exposure under the above conditions the stabilized portion showed a gum value of 46 mg. per 100 cc., while the portion to which azo benzene had not been added showed 224 mg. of gum per 45 100 cc.

Example 2 A blended gasoline in the proportions of approximately 50 parts of straight run gasoline to 50 50 parts of cracked gasoline was stabilized by adding thereto .05% by weight of hydrazo benzene. Samples of this stabilized gasoline and of the same gasoline without the addition of hydrazo benzene were permitted to stand for 45 hours. 55

There was only a trace of gum by the copper dish test in each of the samples at the beginning 01' the test period. At the end of 45 hours the sample to which hydrazo benzene had not been added showed a gum value of 50 mg. per 100 00., while the sample to which hydrazo benzene had been added showed only 6 mg. 01' gum per 100 cc. After a period of 140 hours of standing under the same conditions the former had a gum value 01' 119 mg. per 100 cc., while the latter showed only 37 mg. of gum per 100 cc.

Example 3 To a blended gasoline containing approximately 50 parts of straight run gasoline and 50 parts oi' cracked gasoline there was added 0.1% by weight of azoxy benzene. A sample of the gasoline so treated along with a sample of the gasoline which was not treated were permitted to stand for 76 hours exposed to light. The untreated sample after such period of time showed a gum value of 119 mg. per 100 00., while that of the untreated sample showed a gum value of only 73 mg. per 100 cc.

From these examples it will be seen that although my process does not entirely prevent gum formation in hydrocarbon oils, it is operable to substantially inhibit gum formation and to make the oils more resistant to the formation of gum.

Herein and in the appended claims, when the term "gums is used, it is to be understood to include those solid and/or semi-solid compounds which when not inhibited form due to spontaneous chemical reaction when the low boiling hydrocarbon oils containing gum forming compounds are exposed to storage conditions. Also, in the appended claims, when the amount of substance added to the oil to inhibit gum formation is defined as a small amount, it is to be understood that such term describes amounts which are readily soluble in the oil. Such amounts, in general, will be of the order of 1% or less by weight of the oil.

Also where in the appended claims low boiling hydrocarbon oil, which has been illustrated herein by naphtha, gasoline, and kerosene, is referred to, such term will be understood to contemplate hydrocarbons having a viscosity of the order 01, or, more particularly less than 45 seconds Saybolt Universal at 100 F., and having 5 a 50% boiling point as determined by A. S. T. M. Method D 86-30, below 550 F., those having a 50% boiling point of the order of 350 F'., or lower, being more specifically contemplated.

What I claim is:

1. A motor fuel comprising cracked gasoline normally tending to deteriorate upon storage by gum formation, and stabilized against such gum formation by having incorporated therein a small amount of a substance selected from the group consisting of azo benzene, azoxy benzene and hydrazo benzene, said amount being suiilcient substantially to retard said gum formation.

2. A motor fuel comprising cracked gasoline, normally tending to deteriorate upon storage by gum formation and discoloration, stabilized against such deterioration by the addition thereto of a small amount of azoxy benzene, said amount being sufficient substantially to retard such deterioration.

3. A motor fuel comprising cracked gasoline, normally tending to deteriorate upon storage by gum formation and discoloration, stabilized against such deterioration by the addition thereto of a. small amount of hydrazo benzene, said amount being sufficient substantially to retard such deterioration.

4. A cracked gasoline comprising constituents of the type which are unstable upon storage and 'tend to form gum particularly when exposed to the direct light rays of the sun and containing azobenzene as a stabilizer thereof in quantity less than .1 percent by weight.

5. A cracked gasoline, normally tending to de teriorate upon storage by gum formation and 40 discoloration, stabilized against such deterioration by the addition thereto of a small amount of azo benzene, said amount being sufficient substantially to retard such deterioration.

EDWARD W. McMULLAN.