US1769791A - Art of treating oils - Google Patents

Description

Patented July 1, 1930 UNITED STATES wmnmm a. rumor, or NEWARK,- omo in or ram'rme ores No Drawing. Application filed february 24, 1923,

Serial 1a. 621,076.' Renewed December as, 1925.

This invention relates to art ofltreatingmore or less obscure as to exact chemical treatment of oils with the aid of a catalytic material which may fimction either as an m agent for assisting conversion of relatively heavy oils into lighter oils of lower boiling points, or chiefly as a polymerizing or condensing agent in such manner as to enable removal of undesiralile constituents from a given oil without necessarily eflfecting conversion in the sense of cracking.- In some casesthe catalytic material may function in both ways. It is to be understood that the term catalyst or catalytic agent or material used herein in a broad sense to include a wide range of substances known under that head or under the head of contact, condensing, carrying, accelerating and promoting agents.

While the invention is considered to be of broad scope in its general applicability to oils of widely divergent characteristics and for the manufacture ofvarious products, its most important commercial application at the present time is the treatment of relatively light petroleum distillates, having specific gravities of from about .730 to .830, and distillation ranges lying between about 100 and 600 F., particularly motor fuels, gasolines, and other motor fuels of that general they undergo substantial changes in composition in a comparatively short time under storage conditions, these changes being highly undesirable and prejudicial to attainment of best results in utilizing the fuel. While character, these changes are known to result in the formation of compounds in the gasoline or other motor fuel which, upon evaporation of the motor fuel, manifest themselves in the form of a more or less gummy or resinous residue. In the case of some motor fuels, this resinous or gummy formation occurs to such an extent, that, even without evaporation,-an insoluble residue of said material is deposited upon the bottom of containers in which the motor fuel is stored. In all cases,'however, whether deposition of the gummy material occurs before evaporation or not, the necessary potential constituents thereof are present in ordinary commercial motor fuels, a fact which can be shown by test soon after final distillation. This tendency is usually more pronounced in the case of motor fuels obtained from the various cracking processes, which fuels are characterized by a substantial content of unsaturates. However, the extent to which the undesirable gummy or resinous comnounds are formed does not appear to bear any simple or direct relation to the quantity of unsaturates present in a given motor fuel; and this formation ofgummy or resinous compounds, or instability, is characteristic of many commercial straight-run gasolines as well as gasolines produced by cracking.

It is generally believed that the instability above referred to is due at least largely to polymerization of certain constituents in? variably present in gasolines or other motor 5 fuels as commercially produced heretofore, this polymerization beginning very soon after distillation and progressing usually rather slowlv at a rate depending upon the charatcer of the particular motor fuel in question and the conditions of its storage. Sometimes part of the final polymerization products separate out, but the greater part remain in solution. The practical eifect of this polymerization is that upon evaporation as the resultant gummy polymers which then separate foul the carburetors and valves of internal combustion engines in which the fuel is used, causes excessive carbonizing, and are otherwise seriously objectionable;

The foregoing objections to commercial motor fuels heretofore available have been recognized for a long time and there have been various proposals to obviate them;-but so far as I am aware, none of these prior proposals has roved successful.

It is a specific object of the present invention to rovide a simple and effective method for sta ilizing gasolines and other motor fuels and to produce a motor fuel that does in fact remain stable for long periods. Another object of the invention is to provide a method that is not only simple and effective but is also economical and, in particular, a method by which gasolinesor other motor fuels relatively very high in unsaturates can be stabilized without necessarily reducing theincontent of unsaturates to any substantial extent. Further objects of the invention are in general to enable treatment of any oil product, whether for conversion, stabilization, or for otherwise improving the same, with the aid of a contact or catalyzing agent, particularly a catalytic metallic hali e, brought into contact with the oil in a much more intimate and effective manne than as been possible heretofore.

With these and other objects in view, the invention comprises the novel process which will be hereinafter more fully described in connection with typical illustrative embodiments thereof and will then be more particularly pointed out in the claims.

In order to explain more fully the principles underlying the invention, the stabilization of a motor fuel or gasoline in accordance with the invention will be more particularly referred to and described in detail as illustrating a practical application of the invention in one of its most advantageous forms. Described in general terms, the method of treatment is one which greatly expedites the formation of the polymers constituting the gummy or resinous products that are eventuall formed after ordinary gasoline has stoo for a greater or less period of time after: distillation. It is possible by the treatment to carry this polymerization to a conclusion withina space of time extremely short as compared to the normally rather slow progress of polymerization, and at the same time to effect this result at substantially room temperature without otherwise perceptibly affecting the constitution of the gasoline undergoing. treatment. It is not to be understood, however, that the invention in its broad aspects is restricted to the use of such low temperature. The polymerizing action having been thus expedited and completed, separation of the gummy polymers from the-motor fuel can be readily effected, and the motor fuel is then stable.

In practicing the invenion for stabilizing gasoline the polymerizing agent employed may be any one of various catalytic or contact materials found suitable for the purpose; but in general the action of catalytic metallic halides has been found most effective, anhydrous aluminum chlorid being especially well adapted for use in practice. Anhydrous ferric ch orid also gives good results as does also anhydrous zinc chlorid.

In order to obtain effective action of the polymerizing agent, it is essential that it be brought into extremely intimate reacting contactwith all parts of the motor fuel to be treated. In the best mode of practicing the invention, this is accomplished by treating the motor fuel with a solution of the polyinerizing agent in a solvent that is miscible with or soluble in the motor fuel to such an extent as to ensure distribution of said'agent therethrough and substantially molecular contact with all parts thereof. This mode of procedure enormously increases the velocity of the polymerizing reaction by which gummy constituents are formed. Thus, by dissolving aluminum chlorid in a suitable solvent that is miscible with the gasoline or other motor fuel to be treated, and mixing this solution with the gasoline at ordinary room temperatures, it is found that apparently complete polymerization of the polymerizable constituents present in the untreated gasoline is effected substantially at once, that is, within a very few minutes, or at most a few hours. Some of the products of polymerization separate out in insoluble form very soon after the addition of the aluminum chlorid solution, and with themalso separates a large proportion, usually nearly all, of the aluminum chlorid that was used. In most cases, alarge part of the products of polymerization remain dissolved in the gasoline, together with a minute proportion of the aluminum chlorid. After treatment with the aluminum chlorid solution, the gasoline may or may not be filtered to remove the initial precipitate of polymers and aluminum chlorid, and is then usually distilled to effect separation of the polymers still remaining in the gasoline. The resultant distillate is a gasoline of notably superior characteristics; and when the process is carried out under the best conditions, said distillate is a truly stable gasoline in the sense that even after standing for a long period, say three months or more, it shows substantially no content of gummy or resinous matter/ when subjected to tests for this characteristic. The odor of the gasoline is also generally improved perceptibly, as is also its color, a water white productbeing obtainable by this method from a yellow gasoline- The constitution of the gasoline as regards its content of unsaturates or freedom therefrom, is apparently not altered substantially when the scribed.

process is carried out in the-manner de- In a specific instance, let-it be assumed that the motor fuel to be stabilized is a product obtained by cracking, and is of a type containing up-to' as much asw 20 to 40 per cent unsaturates as determined by the'fuming sulfuric acid test, said type having a specific gravity ranging from .7 30 to .7 80 and a discordance with the process of the invention, it is advisable first to determine how much antillation range lying between "about 100" to 460 or 47 5 F. as outside limits. In treating this or any other type of-motor fuel in achydrou's aluminum chlorid .(Al Cl is required to take up or; otherwise renderinactive any moisture present as such or as H O held either chemically or in some other analogous manner by the hydrocarbons of the mo-' tor fuel since, in order to obtain the desired Al Cl l2H O in dehydrating the soline;

. Accordingly, asample of the motor el is titrated with a standard solution of anhydrousaluminum-chlorid Area in sulf ic ether (ethyl ether) until the-point is reached where I ture in the motor fuel, which quite'commonly' the next drop of standard solution produces a permanently reddish coloration of the ti-' tration mixture. The end point is sharp, and

when titration has been properly performed, the reddish coloration of the mixture at the end point may be instantly dissipated mere- 1y by breathing upon the mixture, the slight amount of moisture thus introduced being.

sufficient to destroy the red color. From the results of this titration it is a simple matter-to compute the amount of anhydrous aluminum chlorid necessary to, combine with themoisamountsto around 0.05-per cent- Only a slight excess over this amount need be used in the stabilizing'treatment; With a motor fuel such as that above assumed, it is found that the employment of from 5 to 6 ounces of dissolved anhydrous aluminum chlorid per each barrel of 42 gallons, is amply suflicient both to allow for dehydration and to ensure stabilization being eflected. p This amounts to, slightly more than one-tenth of one per cent on the weight of gasoline treated, and is fairly respresentative of average practice in carryin on my invention commercially. In genera it is unnecessary to employ more than a fraction of oneper cent, and usually onlya minor fraction. The ability to operate with such small percentages of.cat-' 'alyst indicates how enormously active it is when employed in accordance with the rin- 1 ciples of my invention. It appears pro able that this is dj' i large reto Obtaining I molecular contact, or something analogous thereto, betweenthe aluminum chlorid and gums of gum-forming constituents. aluminum chloride is not soluble in the gasyoline alone to a useful extent.

Where the moisture content of the motor the. gasoline treated, through the distributing action of thesolvent or carrier, although it is also ossibly due to formation of complex combinations between the solvent and the The fuelis considerable, as it may be in some cases, it may be desirable from the standpoint test titration, this amount is added to the gasoline or other motor fuel in. the form of a a. solution in a suitable solvent of aluminum chlorid, and most desirably in a solvent that is miscible with or. soluble in said gasoline or any other motor fuel. Any one of various solvents can be employed, and it is to be understood that the invention is not limited in this respect. It has been found, however,

that alcohol (C H OH) is not a suitable solvent to emloy with aluminum chlorid in practicing the invention, and accordingly alcohol is not to be understood as inclu ed among those recommended herein. Uniform distribution of thereagent through the motor fuel is attained by stirring or otherwise agitating, if necessary. In practice sulfuric ether is an excellent solvent to use, since it dissolves anhydrous aluminum chlorid very readily up to as much as from two to two and one-half times its own weight at room temperature, and is also readil miscible withor soluble in'the motorfue in the proportions necessary to employ it in practicing the invention; Moreover, the finished motor fuel obtained whenan ether-solution of aluminum chlorid is used in carrying out the novel method is of exceptionally good color and stability. Mononitrobenzene'is also a good ,solvent for the purpose. Where ether is employed, it is good iao izing agent. Immediately after theether so-' lutionhas been added, a precipitate begins to separate out, and in order to allow. ample hour to twenty-fourhours. The precipitate time to complete this separation it is good practice to allowthe treated motor fuel to I stand fora period that may range from one comes'out and settles in the form of more or less irregularly shaped gummy particles that are easily separated from the litguid either by filtration or by decantation. eparation of the recipitate at this stage is optional althoug in general it is to be recommended if the precipltate is at all large. An examination of t e precipitate shows that it consists largely of gummy polymers to ether with nearly all of the aluminum chlori originally introduced into the motor fuel. The clear solution contains, however, a large prortion of the ormed polymers that remain 'ssolved and do not se arate at this stage, together with a trace of aluminum chlorid. It is sometimes desirable also, before separating the precipitate, to eliminate even the residual trace of aluminum chlorid from the motor fuel by treating the same with a suitable preci itating agent for aluminum as, for exam e, by agitating with a small quantity of ry sodium bicarbonate, or with a small amount of an alcoholic solution of caustic soda or potash, In this case, the motor fuel, after separation of insoluble matter by filtration or decantation, contains substantially no trace of aluminum chlorid, and is also substantially neutral in reaction.

In the specific example lire assumed, the treated motor fuel is next r distilled to separate'therefrom the polymerized constituents that still remain in solution as result of the treatment with aluminum chlorid. This distillation may be effected in the usual manner and requires no special precautions other than those employed in ordinary practice. The distillate is a finished motor fuel which is stable, sweet in odor and of excellent color, as already pointed out. The content of unsaturates is substantially the same as in the original motor fuel, about 30 percent in a typical instance. This is a highly advantageous feature of the process, since a motor.

uel containing unsaturates, when stabilized in accordance with the invention, gives better mileage and greater powerthan a motor fuel that contains no unsaturates. Furthermore, it is to be es ecially noted that this high grade motor uel'is obtainable without the .large refinery loss resulting from the commonly employed sulfuric acid treatment for removal of unsaturates,

In the case of motor fuels that are high in unsaturates, such as that whose treatment has been described in detail above, it is generally the best practice always to redistill after treatment with the solution of anhydrous aluminum chlorid. However, in the case of straight run gasolines, for example, which are commonly obtained by topping crude petroleum and which are often practically free from unsaturates, the benefits of the invention can be realized to a very substantial extent-even where there is no redistillation after treatment with the solution of anhydrous aluminum chlorid; althou h even straight-run gasolines should be redistilled to attain the best results. Man

straight-run gasolines, however, contain suc comparatively small amounts of constituents polymerizable to gums that they are generally quite acceptable commercially even though not stable, strictly speaking. In the case of such gasolines, treatment with a solution of anhydrous aluminum chlorid or other suitable polymerizing agent has the effect of polymerizing whatever polymerizable constituents are present, but the polymers do not separate upon standing at ordinary temperatures to so great an extent as in the case of a motor fuel high in unsaturates. There is usually some separation of 01 mers, together with practically all 0 the aluminum chlorid; but a large proportion of them remains dissolved in the motor fuel. Nevertheless the improvement in odor and color of the motor fuel, even without redistillation after treatment, is so marked as to render it of much greater commercial value. In such cases, after separation of such solid matter as may precipitate upon standing for from one to twenty-four hours in the cold, but without re-distilling, the treated motor fuel can be marketed as a finished product of a quality superior to untreated straight-run gasolines. As before stated, however, gasoline so treated, but not distilled, is not stable because it ,still contains dissolved gummy polymers'which are deposited upon evaporation of the gasoline. v

From the foregoing it is apparent that, while redistillation after treatment with aluminum chlorid is an important feature of the invention in certain of its advantageous embodiments, it is not to be regarded as an indispensable step of the novel process in all cases.

In the manufacture ofgasolines and like motor fuels by topping crudes or b ing, it is common practice to obtain rom the topping still, cracking still, cracking tubes, or other suitable source, a crude motor fuel which is then re-run to improve its boiling range by eliminating the heavy ends contained therein. Where this is customary, the treatment with a solution of aluminum chlorid in accordance with the invention may most advantageously be applied to the crude distillate before it is re-run or re-distilled.

This involves no change in the regular practice other thanthe addition of the aluminum chlorid solution and mixing thereof with the crude distillate by stirring or agitation,.if desired, together with optional removal of the gummy precipitate that thereafter separates upon standing; all of which is readily interposed between the two usual steps of obtaining the crude motor fuel and re-running. It is to be understood, therefore that the process of the invention may comprise, in

crack-.

one of its advantageous practical embodiments, the complete series of steps above set forth, beginning with the obtaining of a crude gasoline or .the like by straight-run distillation of, or by cracking, petroleum or other relatively heavy oil material.

A stable petroleum distillate obtained in accordance with the process of the invention is believed to be a broadly novel product in the art anddistinguishable from motor fuels heretofore known. In particular, a stable motor fuel containing unsaturates, especially a substantial or high percentage thereof, say 10 per cent or more, is a novel product notably superior to motor fuels heretofore available.

In order to make clear the distinction between a truly stable motor fuel-as obtainable by the practice of the invention, and the unstable motor fuels heretofore exclusively available, it may be well to outline briefly a common test for stability as employed in regular practice. The tendency of a motor fuel to change in constitution or composition is manifested, as already pointed out, by

gummy substances developed therein and sometimes eventually deposited therefrom in insoluble form after the lapse of a period oftime that varies with difierent motor fuels. Deposit of these gummy substances may-be hastened by evaporation, and the amount deposited will depend to a great extent upon the conditions of the evaporation. Accordingly, theamount of gummy substance deposited by evaporation of a given volume of motor fuel under standard conditions is generally taken to indicate the degree of stability or instability of the motor fuel. An investigation of the best motor-fuels heretofore known in the art shows that slow evaporation of cubic centimeters in an open dish gently heated invariably yields a residue of at least three to five milligrams, and a motor fuel leaving. so small a gummy deposit as this is very exceptional. As a rule the amount is larger than this and it commonly ranges anywhere from 20' to 50 mgs. In contrast to this, a motor fueltreated with a solution of aluminum chlorid and then re-distilled, as herein disclosed,

when subjected to the evaporation test mentioned, leaves at the most a substantially smaller residue than three milligrams upon evaporation of 50 cubic centimeters thereof; and as a rule the residue does not exceed two milligramsat the outside, being more commonly as little as 0.5 milligram.

The principles of the invention may also be extended to the, stabilizing or improvement generally of other petroleum products, such as .lubricating oils, parafline, -and ..the like,

which are not necessarily distillates, by treatment with a solution of a catalytic metallic halide, especially anhydrous aluminum chlorid,in a suitable solvent miscible with the oil, whereby substantially molecular or analogous contact between the oil and the. catalytic agent or assistant ,is attained, and the efficiency of the converting action. is enhanced.

The principles of the invention may be extended further to cases where production of polymerized materials from a hydrocarbon oil or distillate is a primary object rather than stabilization or other improvement'of the hydrocarbon oil itself; 7 The polymers obtained in treating gasoline or the like in ac- .cordancewith the present invention have value in the manufacture of lubricants, resins, and other products; and the production of such polymers is therefore an important phase of the invention. In thisparticular aspect of the invention also, the'novel'process is especially applicable to cracked mineral oil distillates since .these are most likely to yield polymers in commercial quantities upon treatment. I

It is to be understoodgthat the invention is not limited to the particular detailshereinabove set forth by way J ample, but that it is susceptibleof being varied considerably in practice without departingfrom the underlying principles mvolved. r

What I claim is:

1. The process-of improving a hydrocarbon motor fuel which comprises commm'e gling therewith a solution of a catalyt1c metallic halide in ethyl ether at atemperature favorable to polymerization of polymerizable constituents resent in said'motor fuel but insufficiently 'gh to effect substantial breaking down or cracking.

2. The process of stabilizing'apetroleum distillate coming within the range covered by kerosene and lighter fractions, which comprises commingling such a distillate w th a solutionof aluminum chloride-in ethyl ether.

3.; The process of producing a stable motor fuel. which comprises subjectmg an unstable petroleum'distillate having a specific; gravity of between .730 and .780 to the action of a metallic halide having a polymerizing action on gum-forming constituents 1n said d1st1l-' 4. The process of producing a stabilized petroleum product which comprises subjecting a cracked petroleum distillate having a specific gravity of between .730 and .830 to the action of a metallic halide having a polyof illustrative exethyl -ether.- F

merizing action'on gum-forming constituents in, said distillate, said metallic halide being dissolved in ethyl ether, and separating res "sultantigum'my products from the liquid.

' 5. The recess of producing a stable motor fuel whic comprises subjecting a hydrocarbon motor fuel distillate to the action of a solution of a catalytic metallic halide in ethyl ether, the amount of said metallic halide used being less than one per cent of the distillate by weight, and separating resultant products from the li uid.

6. a he process defined in c aim 5, in which so aration of resultant gummy products is efl ected by re-distilling.

7. The process defined in claim 5, in which the catalytic metallic halide is' anhydrous aluminum chloride, employed in amount equal to less than one per cent of the distillate by wei ht. x I

8. T 'e process-of'producingfa stable motor fuel which comprises subjecting a crude motor fuel containing up to about 40 per cent of,,unsaturates to the polymerizing action of less thani-l per cent of anhydrous aluminum chlorid dissolved in ethyl ether, said motor fuel" having been derived from troleum oil b suitable heat treatment, and 'stilling a su stantially stable motor fuel product. from the crude 1 motor fuel thus treated. -V m a 9. The process of modifying hydrocarbon oils which comprises subjecting a hydrocarbon oil under reacting conditions to the modifying action of a catalytic metallichalicle dissolved in ethyl ether;

10. The process ofmodifying hydrocarbon oils contammg polymeriza'ble constituents which comprises subjecting such a hydro-- carbon oil under reacting conditions to the action of a solution of aluminum chlorid in 11. s process of modifying hydrocarbon oils which comprises subjecting a hydrocarbon oil under reacting conditions to the modiiying action of a catalytic metallic halide dissolvedin an ether of the oxide type.

12. V The-process of modifying hydrocarbon oils which comprises subjecting a hydrocar- ;b0n oil under reacting conditions to the modifying'action of aluminum chlorid in an ether I of the oxide type.

13. The process of producing a stable motor fuel whlch comprises subjecting a hydrocarbon motor fuel distillate to the action of a solution of a catalytic metallic halide in an ether of the oxide type, the amount ofsaid ether used being less than one per cent of the distillate bv weight, and separating resultant gumm products from the liquid.

14. he process of producing a stabilized petroleum product which comprises subject-- ing a'cr acked petroleum distillate having a specific gravity of between .7 30 and .830 to the action of a metallic halide having a poly- In testimony whereof Ihereunto aflix my signature.

WILLIAM G. LEAMON.