US3199965A - Liquid hydrocarbons - Google Patents

Description

United States Patent par 3,19%)65 LIQUED HYDRQCARBONS Harry J. Andreas, Jr., Pitrnan, and Paul Y. C. Gee, Woodbnry, N..l., assignors to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Filed June 25, 1964, Ser. No. 378,026 13 Claims. ((31. 44-71) This invention relates to improved liquid hydrocarbons, and, in one of its aspects, relates more particularly to improved liquid hydrocarbons in the form of petroleum distillate hydrocarbon fractions. Still more particularly, in this aspect, the invention relates to improved liquid hydrocarbons in the form of non-lubricating distillate fuel oils, which, in their uninhibited state tend to clog screens, rust metal surfaces, and to emulsify under the conditions of use.

This application is a continuation-in-part of our copending application, Serial No. 715,200, filed February 14, 1958, now abandoned, and a continuation-in-part of our copending application Serial No. 187,185, filed April 13, 1962, now abandoned.

It is well known that liquid hydrocarbons in the form of fuel oils are prone to form sludge or sediment during periods of prolonged storage. This sediment, has an adverse eifect on burner operation, by reason of its tendency to clog screens and nozzles. In addition to sediment which is formed during storage, most fuel oils contain other impurities, such as rust, dirt and entrained water. Such sediment and impurities tend to settle out on equipment parts, such as nozzles, screens, filters, and the like, thereby causing clogging and failure of equipment. Furthermore, another undesirable characteristic of petroleum distillate fuel oils is their tendency to form objectionable emulsions.

A factor, incident to the storage and handling of distillate fuels, is the breathing of storage vessels. This results in the accumulation of considerable amounts of water in the tanks, and presents the problem of rusting. Consequently, when the fuel is removed for transportation, sufficient water may be carried along to cause rusting of ferrous metal surfaces in pipelines, tankers, and the like.

Heretofore, in the case of fuel oils, it has been the practice to overcome the aforementioned difliculties through the use of a separate additive for each purpose, i.e., with a sediment inhibitor, an anti-screen clogging agent, an antirust agent, and an emulsion inhibitor. The use of several additives, however, gives rise to problems of additive compatibility, thus restricting the choice of additive combinations. In addition, of course, the use of a plurality of additives unduly increases the cost of fuel. It is therefore highly desirable from a commercial standpoint to overcome the aforementioned difficulties through the use of a single additive agent, which is effective against sedimentation, screen and nozzle clogging, rusting of ferrous metal surfaces and emulsification.

Accordingly, it is an object of this invention to provide liquid hydrocarbons having improved properties.

Another object of the invention is to provide improved liquid hydrocarbons in the form of fuel oils containing a single additive which is adapted to inhibit sedimentation, prevent screen clogging, prevent rusting of ferrous metal surfaces with which these fuels come into contact, and to inhibit emulsification.

Other objects and advantages inherent in the invention will become apparent to those skilled in the art from the following detailed description.

It has now been found that all of the aforementioned difficulties, viz., sedimentation, screen clogging, rusting, and emulsification, can be overcome by the use of a ice single fuel oil addition agent. In this respect, it has now been found that distillate fuel oils containing minor amounts of certain amic acids, are effectively inhibited, simultaneously against all of the aforementioned difiiculties.

The present invention, in general, provides improved liquid hydrocarbons, preferably in the form of non-lubricating petroleum distillate hydrocarbons, containing from about 0.5 to about 200 pounds per 1000 barrels of liquid hydrocarbon of the condensation product of citric acid with a primary alkyl amine, having from about 6 to about 30 carbon atoms, with a tertiary alkyl group attached to a nitrogen atom. In these compositions, the molar ratio of amine to citric acid preferably varies from between 1 and 2.

The addition agents contemplated herein are the condensation products of citric acid with the aforementioned primary amines. They are produced by reacting the amine with citric acid, in a molar ratio of amine to citric acid of 1:1 or 2:1, at a temperature varying between about C. and C. for a period of from about 2 to 5 hours. The reaction is accompanied by the elimination of water to form amide groups. Thus, it is preferred to carry out the condensation reaction employing an azeotrope to remove the water, such as benzene, toluene, xylene, etc.

The amines utilizable in forming the citric acid condensation products are alkyl amines having from about 6 to about 30 carbon atoms per molecule, as indicated above, or mixtures of amines, in which the amino (NH group is attached to a tertiary carbon atom. These amines all contain the terminal group,

non-limiting examples of such amine reactants are t-heXyl primary amine, t-octyl primary amine, t-decyl primary amine, t-dodecyl primary amine, t-tetradecyl primary amine, t-octadecyl primary amine, t-eicosyl primary amine, t-docosyl primary amine, t-tetracosyl primary amine, and t-triacontyl primary amine.

The amine reactants can be prepared in several Ways well known to those skilled in the art. Specific methods of preparing the t-alkyl primary amines are disclosed in the Journal of Organic Chemistry, vol. 20, page 295 et seq. (1955). Mixtures of such amines can be made from a polyolefin fraction (e.g., polypropylene and polybutylene cuts) by first hydrating with sulfuric acid and Water to the corresponding alcohol, converting the alcohol to alkyl chloride with dry hydrogen chloride, and finally condensing the chloride with ammonia, under pressure, to produce a t-alkyl primary amine mixture.

The liquid hydrocarbons that are improved in accordance with the present invention are those boiling from about 50 F. to about 750 F., and which are free of any added iron-containing material, i.e., liquid hydrocarbons that are free of iron-containing materials other than that normally present in the fuel as obtained from the source thereof, or derived from ferrous containers or pipelines. Thus, the liquid hydrocarbons that are contemplated for treatment in accordance with the present invention, are free from added iron-containing materials such as iron anti-knock compounds, or other iron-containing agents. Of particular importance are liquid hydrocarbons of the following types: liquid hydrocarbons comprising nonlubricating petroleum distillate fuel oils having an initial boiling point above gasoline and an end boiling point higher than about 600 F. and boiling substantially continuously throughout their distillation range; liquid hydrocarbons comprising petroleum distillate fuel oils boiling within the range from about 50 F. to about 150 F., and which are normally subject to low temperature deterioration prior to being combusted; liquid hydrocarbons having an initial boiling point below about 350 F. and an end boiling point higher than about 600 F; liquid hydrocarbons having an initial boiling point of at least 100 F. and an end boiling point higher than about 600 F.; and liquid hydrocarbons having an initial boiling point from about 100 F. and below about 350 F. and an end boiling point higher than about 600 F.

A more specific type of liquid hydrocarbon, treated in accordance with the present invention, is one normally having a tendency to form sediment during storage and being free of any added iron-containing material, containing a stabilizing amount of a condensation reaction product of citric acid with a tertiary-alkyl primary amine of the formula having about between to carbon atoms and wherein R and R are lower molecular weight alkyl groups and R is a higher molecular weight alkyl group, the molar ratio of amine to acid in the reaction mixture being 1:1.

Another specific type of liquid hydrocarbon treated in accordance with the present invention, is a non-lubricating petroleum distillate hydrocarbon fraction normally having a tendency to form sediment during storage and being free of any added iron-containing material, containing a stabilizing amount of a condensation reaction product of citric acid with a tertiary-alkyl primary amine of the formula having about between 10 to 20 carbon atoms and wherein R and R are lower molecular weight alkyl groups and R is a higher molecular weight alkyl group, the molar ratio of amine to acid in the reaction mixture being 121.

With respect to the term distillate fuel oils it should be noted that this term is not intended to be restricted to straight-run distillate fractions. The distillate fuel oils can be straight-run distillate fuel oils, catalytically or thermally cracked (including hydrocracked) distillate fuel oils, or mixtures of straight-run distillate fuel oils, naphthas and the like, with cracked distillate stocks. Moreover, such fuel oils can be treated in accordance with well known commercial methods, such as, acid or caustic treatment, hydrogenation, solvent refining, clay treatment, and the like.

The distillate fuel oils are characterized by their relatively low viscosities, pour points, and the like. The principal property which characterizes the contemplated hydrocarbons, however, is the distillation range. As mentioned hereinbefore, this range will lie between about 100 F. and about 750 F. Obviously, the distillation range of each individual fuel oil will cover a narrower boiling range falling, nevertheless, within the above-specified limits. Likewise, each fuel oil will boil substantially continuously throughout its distillation range.

Particularly contemplated among the fuel oils are Nos. 1, 2, and 3 fuel oils used in heating and as diesel fuel oils, and the jet combustion fuels. The domestic fuel oils generally conform to the specifications set forth in ASTM Specifications D39648T. Specifications for diesel fuels are defined in ASTM Specifications D97548T. Typical jet fuels are defined in Military Specification MIL-I 56243.

The amount of citric acid-amine condensation product that is added to the distillate fuel, in accordance with this invention, will depend, of course, upon the intended purpose and the particular condensation product selected, as

they are not all equivalent in their activity. Some may have to be used in greater concentrations than others t be effective. In most cases, in which it is desired to obtain all of the aforesaid beneficial results in fuel oil, namely, to inhibit sedimentation, to reduce screen clogging, to prevent rusting of ferrous metal surfaces, and to inhibit emulsification, additive concentrations varying between 10 pounds per thousand barrels of oil and about 200 pounds per thousand barrels of oil will be employed It may not always be desired, however, to accomplish all of the aforementioned results. In such cases, where it i desired to effect only one or two of such results lower concentrations can be used. Thus, if it is desired only to prevent rust under dynamic conditions, as in a pipeline, it has been found that concentrations as low as about 2.5 ppm, i.e., about 0.5 pound of additive per thousand barrels of oil, are effective. In general, therefore, the amount of citric acid-amine condensation product that can be added to the distillate fuel, in order to achieve a beneficial result, will vary generally between about 0.5 pound per thousand barrels of oil and about 200 pounds per thousand barrels of oil. Preferably, it will vary between about 10 and about 200 pounds per thousand barrels of oil.

If it is desired, the distillate fuel composition can contain other iron-free additives for the purpose of achieving other results. Thus, for example, there can be present foam inhibitors, ignition and burning quality improvers, scavengers, and preignitiou agents. Examples of such additives are silicones, dinitropropane, amyl nitrate, metal sulfonates, haloalkanes, phosphate esters, and the like.

T he following specific examples are for the purpose of illustrating the distillate fuel compositions of this inven tion, and of exemplifying the specific nature thereof. included in such examples is the preparation of condensation products of citric acid and n-alkyl primary amines and their use in fuel oils for the purpose of comparison with similar condensation products, but in which the amine was a t-alkyl amine as embodied herein. As is evident from the data set forth hereinafter, the use of the condensation products embodied for use herein markedly inhibit emulsification whereas similar condensation products devoid of the t-alkyl group provide fuel oils that emulsify severely. It is to be strictly understood, however, that this invention is not to be limited by the particular additives and fuels, or to the operations and manipulations described therein. Other condensation products and fuels, as discussed hereinbefore and embodied herein, can be used, as those skilled in the art will readily appreeiate.

The amine reactants used in the following examples are mixtures of pure amines. Amine A is a mixture of primary amines having a carbon atom of a tertiary butyl group attached to the amino (-Nl-l group and containing 12 to 15 carbon atoms per amine molecule and averaging 12 carbon atoms per molecule. This mixture contains, by weight, about percent tertiary dodecyl amine, about 10 percent tertiary pentadecyl amine, and relatively small amounts, i.e., less than about 5 percent of amines having less than 12 or more than 15 carbon atoms.

Amines B and C are mixtures of primary amines (RNH having the weight percent composition set forth in the following tabulation:

Octadecadienyl 45 EXAMPLE 1 A mixture of grams (0.5 mole) citric acid monohydrate, grams (0.5 mole) amine A, and 100 grams xylene was gradually heated to 175 C. The reaction mixture was held at that temperature until evolution of water ceased (about 3 hours). The final product was clear and required no filtration.

EXAMPLE 2 A mixture of grams (0.5 mole) citric acid monohydrate, 150 grams (0.5 mole) amine B, and 100 grams toluene was refluxed at 114 C. until evolution of water ceased (about 3 hours). The product Was clear and not filtered.

EXAMPLE 3 A mixture of 105 grams (0.5 mole) citric acid monohydrate, 200 grams ("1.0 mole) amine A, and grams xylene was refluxed at C. until water stopped coming over (about 3 hours). The final product was clear and not filtered.

EXAMPLE 4 A mixture of 70 grams /3 mole) critic acid monohydrate, 100 grams /3 mole) amine C, and 100 grams toluene was refluxed at 114 C. for 3 hours. Then, the temperature was gradually increased to C. and was maintained until evolution of water had ceased (about 1 hour). The product was filtered through filtering clay.

Sedimentation The test used to determine the sedimentation charac teristics of fuel oils is the 110 F. Storage Test. In this test, a SOO-milliliter sample of the fuel oil under test is placed in a convected oven maintained at 110 F. for a period of 12 weeks. Then, the sample is removed from the oven and cooled. The cooled sample is filtered through a tared asbestos filter (Gooch crucible) to remove insoluble matter. The weight of such matter in milligrams is reported as the amount of sediment. A sample of the blank, uninhibited oil is run along with a fuel oil blend under test. The effectiveness of a fuel oil containing an inhibitor is determined by comparing the weight of sediment formed in the inhibited oil with that formed in the uninhibited oil.

EXAMPLE 5 The additives described in Examples 1 through 4 were blended in portions of a test fuel oil and the blends were subjected to the 110 F. Storage Test. The test results comparing the blended fuels and uninhibited fuels are set forth in Table I. The test fuel oil is a blend of 60 percent distillate stock obtained from continuous catalytic cracking and 40 percent straight-run distillate stock. It has a boiling range of between about 320 F. and about 640 F., and is a typical No. 2 fuel oil.

Screen clogging The anti-screen clogging characteristics of a fuel oil were determined as follows: The test is conducted using a Sundstrand V3 or S1 home fuel oil burner pump with a self-contained 100-mesh Monel metal screen. About 0.05 percent, by weight, of naturally-formed fuel oil sediment, composed of fuel oil, water, dirt, rust, and organic sludge is mixed with 10 liters of the fuel oil. This mix- 6 ture is circulated by the pump through the screen for 6 hours. Then, the sludge deposit on the screen is washed off with normal pentane and filtered through a tared Gooch crucible. After drying, the material in Gooch crucible is washed with a 5050 (volume) acetone-methanol mixture. The total organic sediment is obtained by evaporating the pentane and the acetone-methanol filtrates. Drying and weighing the Gooch crucible yields the amount of inorganic sediment. The sum of the organic and inorganic deposits on the screen can be reported in milligrams recovered or converted into percent screen clogging.

EXAMPLE 6 Using the test fuel oil described in Example 5, blends of the additives of Examples 1 through 4 in this fuel were prepared. Each blend was subjected to the Screen Clogging Test, as aforedescribed. Test results are set forth in Table II.

TABLE II.-SCREEN CLO G GING Rust test in fuel oil The rusting characteristics of fuel oils were determined in the Static Rust Test, which simulates conditions encountered in storage vessels, such as, the home fuel storage tank. In this test, a strip of 16-20 gauge sand blasted steel plate is placed in a clear quart bottle. The length of the strip is sufiicient to reach from the bottom of the bottle into the neck of the bottle without interfering with the cap. One hundred cc. of synthetic sea water with pH adjusted to 5 (ASTM D-665) and 750 cc. of test oil are placed in the bottle. The bottle is capped tightly, shaken vigorously for one minute, and permitted to stand quietly at 80 F. for 21 days. At the end of that time the amount of rust that occurs on the surface of the plate immersed in the water is used as a measure of the effectiveness of the fuel to inhibit rusting in storage vessels. It is generally preferred that no more than 5 percent of the surface should be rusted. This test is much more severe than the ASTM Rust Test. Many compositions that pass the ASTM test fail in the Static Test. On the other hand, materials that pass the Static Test always pass the ASTM test.

EXAMPLE 7 Blends of the additives described in Examples 1 through 4, in portions of the fuel oil defined in Example 5, were prepared. Each blend was subjected to the Static Rust Test. Pertinent data are set forth in Table III.

TABLE III.-STATIC RUST TEST It will be apparent, from the data set forth in Tables I through III, that the citric acid-amine condensation products, whether or not derived from normal-alkyl amines or tertiary-alkyl amines, are effective to reduce sedimentation and screen clogging and to inhibit rusting of ferrous metal surfaces in fuel oil.

However, to impart to the distillate fuel oils the added desirable property of inhibition against emulsification, it has been found that such condensation products from n-amines (Examples 2 and 4) do not inhibit emulsification whereas the products from the defined t-carbon atom containing amines (Examples 1 and 3) markedly inhibited emulsification. To illustrate such a function performed by the additives useful for practice of this invention, the condensation products of Examples 1 to 4 were individually blended with the distillate fuel oil defined in Example 5 in concentrations of 25, 50 and 100 lbs/thousand barrels of the fuel oil and subjected to the following emulsion test.

Emulsion test The procedure for the fuel oil emulsion test is as follows: a 200 milliliter portion of the fuel to be tested and 20 milliliters of distilled water are placed in a clear glass pint bottle. The bottle is tightly capped and set in an Everbach mechanical shaker in a horizontal position such that the maximum degree of agitation is afforded. The shaker is run at its maximum setting for 5 minutes. The bottle is then removed and allowed to stand in an upright position in the dark for 24 hours. At the end of the 24 hour settling period, the appearance of the water layer is noted. The fuel layer is siphoned oif, care being taken not to disturb the oil-water interface, and is discarded. A fresh portion of the fuel oil being tested is then added. The described sequence of steps is repeated. If no emulsion appears in the Water layer after this sequence has been performed ten times, the oil is considered to have passed the test. On the other hand, if, after any 24 hour settling period in the procedure, there is any degree of emulsification in the water layer, the fuel is considered to have failed the test. This test procedure has been found to provide emulsions in inhibited oils similar to emulsions which occur in these same oils only after prolonged periods of normal handling and storage in the field on a commercial basis.

RATING SCALE FOR REPORTING EMULSION TEST RESULTS Description of Emulsion Clean break on the interface of oil and water. No dirt, skin, or bubbles present. 1 Very slight skin at the oil-water interface that usually does not break on tilting the bottle. Skin at oil-water interface, heavier than #1 and usually accompanied with dirt and bubbles on the skin. No evidence of any white emulsion. 3 First sign of the white emulsion. Usually forms at the bottom and in the center of the bottle. It is circular in shape and approximately A to 1 inch in diameter, Approximately the same amount of emulsion on the bottom of the bottle as #3. However, emulsion is also beginning to form at oil-water interface and extends to A downward into the Water layer. Roughly of water layer occupied by the emulsion. 5 Circular emulsion at bottom of bottle extends outward and upward resembling spokes. Emulsion at the interface a little thicker than #4. 6 More emulsion than #5. Thin film of emulsion forming on sides of bottle surrounding the water layer. Water is still visible looking through the sides and looking up from the bottom of the bottle. Emulsion on bottom of Water layer is almost solid. Emulsion on sides of bottle is broken in a few spots enabling the operator to see the water layer. 8 Semi-solid emulsion with perforations or bubbles similar to a honeycomb. No water visible except that seen in the bubbles. Same emulsion as #8 but with less bubbles. 75-90% emulsion is solid.

Rating 10 Almost completely solid emulsion with only a few air bubbles visible.- 11 Completely solid emulsion (Mayonnaise type).

The results obtained from the foregoing emulsion test were as follows:

Cone. of additive Remarks Rating lbs./ 1,000 bbls.

Base fuel plus Example 25 Severe emulsion after 11 2. first contact.

50 do ll do 11 25 Severe emulsion after 8 first contact.

Do 8 Base fuel plus Example 1 Do. 1 Do l. 1 Base fuel plus 1 Do 1 Do 1 It is apparent from the foregoing that the additives (Examples 1 and 3) embodied for use herein are markedly effective as emulsion inhibitors whereas corresponding additives (Examples 2 and 4) but devoid of a t carbon atom as aforediscussed resulted in severe emulsification.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may he resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand.

We claim:

1. A liquid hydrocarbon, normally having a tendency to form sediment during storage and being free of any added iron-containing material, containing a stabilizing amount of a condensation reaction product of citric acid and a tert-iary-alkyl primary amine having from about 6 to about 30 carbon atoms with a tertiary alkyl group attached to a nitrogen atom.

2. The composition of claim 1 wherein said condensation reaction product is present in an amount from about 0.5 to about 200 pounds per 1,000 barrels of liquid hydrocarbon.

3. The composition of claim 1 wherein the liquid hydrocarbon contains a stabilizing amount of a condensation reaction product of citric acid and a mixture of tertiary-alkyl primary amines having from about 12 to about 15 carbon atoms per amine molecule with a tertiary-alkyl group attached to a nitrogen atom.

4. The composition of claim 1 wherein the liquid hydrocarbon comprises a petroleum distillate fuel oil having an initial boiling point above gasoline and an end boiling point higher than about 600 F. and boiling substantially continuously throughout its distillation range.

5. The composition of claim 1 wherein the liquid bydrocarbon comprises a petroleum distillate fuel oil boiling within the range from about 50 F. to about l50 E, and is normally subject to low temperature deterioration prior to being combusted.

6. The composition of claim 1 wherein the liquid bydrocarbon has an initial boiling point below about 350 F. and an end boiling point higher than about 600 F.

7. The composition of claim 1 wherein the liquid hydrocarbon has an initial boiling point of at least 100 F. and an end boiling point higher than about 600 F.

8. The composition of claim 1 wherein the liquid hydrocarbon has an initial boiling point from about 100 F. and below about 350 F. and an end boiling point higher than about 600 F.

9. A liquid hydrocarbon normally having a tendency to form sediment during storage and being free of any added iron-containing material, containing a stabilizing amount of a condensation reaction product of citric acid with a tertiary-alkyl primary amine of the formula having about between 10 to 20 carbon atoms and wherein R and R are lower molecular weight alkyl groups and R is a higher molecular weight alkyl group, the molar ratio of amine to acid in the reaction mixture being 1:1.

'10. A non-lubricating petroleum distillate hydrocarbon fraction normally having a tendency to form sediment during storage and being free of any added iron-containing material, containing a stabilizing amount of a condensation reaction product of oitiric acid with a tertiaryalkyl primary amine of the formula R1 R3( JNH in having about between 10 to 20 carbon atoms and wherein R and R are lower molecular weight alkyl groups and R is a higher molecular weight alkyl group, the molar ratio of amine to acid in the reaction mixture being 1: 1.

11. A petroleum distillate fuel oil having an initial boiling point of at least abount 100 F. and an end boiling point not higher than about 750 F. and boiling substantially continuously throughout its distillation range containing between about 0.5 pound and about 200 pounds per 1000 barrels of fuel of the condensation product of one mole of citric acid with from one to two moles of an alkyl primary amine having between about 6 and about 30 carbon atoms and a tertiary alkyl group attached to the nitrogen atom.

12. A petroleum distillate fuel oil having an initial boiling point of at least about 100 F. and an end boiling point not higher than about 750 F. and boiling substantially continuously throughout its distillation range containing between about 0.5 pound and about 200 pounds per 1000 barrels of fuel of the condensation product of equimolecular quantities of citric acid and a mixture of tertiary-alkyl primary amines containing 12 to 15 carbon atoms per amine molecule and having a carbon atom of a tertiary alkyl group attached to the amino group.

13. A liquid hydrocarbon jet fuel containing a stabilizing amount of a condensation reaction product of citric acid with a tertiary-alkyl primary amine of the formula having about between 10 to 20 carbon atoms and wherein R and R are lower molecular weight alkyl groups and R is a higher molecular weight alkyl group, the molar ratio of amine to acid in the reaction mixture being 1:1.

References Cited by the Examiner UNITED STATES PATENTS 2,387,501 \lO/45 Dietrich. 2,493,715 1/50 Christ 4471 2,598,213 5/52 Blair 252-855 3,035,907 5/62 Halter et al. 44-71 FOREIGN PATENTS 790,604 2/58 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

Claims (1)

1. A LIQUID HYDROCARBON, NORMALLY HAVING A TENDENCY TO FORM SEDIMENT DURING STORAGE AND BEING FREE OF ANY ADDED IRON-CONTAINING MATERIAL, CONTAINING A STABILIZING AMOUNT OF A CONDENSATION REACTION PRODUCT OF CITRIC ACID AND A TERTIARY-ALKYL PRIMARY AMINE HAVING FROM ABOUT 6 TO ABOUT 30 CARBON ATOMS WITH A TERTIARY ALKYL GROUP ATTACHED TO A NITROGEN ATOM.