Process of preparing novel micro emulsions

Abstract

This invention concerns a process for preparing water-in-petroleum type of micro emulsions. These emulsions are stable and clear and contain substantially greater quantities of water-soluble additives than it is normally possible to disperse when using the petroleum fraction alone.

Parent Case Text

This application is a continuation-in-part of Ser. No. 803,459 filed Feb. 28, 1969 now abandoned in the United States Patent Office.

Description

This invention relates to a process for increasing the quantity of water soluble additives that can be incorporated into petroleum fractions and to the emulsions produced therein.

More particularly, this invention concerns a process for preparing stable, clear micro emulsions of petroleum fractions and water containing substantially greater quantities of water-soluble additives than is possible using the hydrocarbon fractions alone.

The use of additives in petroleum fractions derived from petroleum refining is well established in the industry. Additives are commonly utilized to enhance, improve, modify, suppress or change some property or characteristic of the hydrocarbon fraction treated. For example, lubricating oils contain viscosity index improvers, pour point depressants, oxidation and corrosion inhibitors, while furnace and residual fuel oils employ stabilizers, corrosion inhibitors and the like. Middle distillates, such as diesel fuels and jet fuels particularly, utilize a variety of additives to improve performance. These include ignition improvers, cetane improvers, corrosion inhibitors, deicers among others. Many additives, including octane number improvers, gum inhibitors, metal deactivators and rust preventives are commonly employed in gasolines.

One of the limiting factors in the use of many potentially attractive additives is their poor solubility in the neat petroleum fraction to be treated. For example, a good number of amides, diols, alkanolamines, polyamines and aldehydes which have good solubility in water are insufficiently soluble in petroleum fractions to impart any significant additive effect. As used herein, good solubility in water is defined as permitting a clear solution containing at least a 10 percent by weight of the additive in water to be prepared which is stable at 25.degree. C. Insufficiently soluble in a petroleum fraction is defined as not permitting a clear 0.1 percent by weight solution of the additive to be prepared which is stable at 25.degree. C. (77.degree. F.) in petroleum fractions covering a range of volatility from an Initial Boiling Point (IBP) of about 70.degree. F. (21.degree. C.) to an End Point (EP) of about 650.degree. F. (343.degree. C.) as determined using ASTM Method D-86.

The use of micro-emulsions of petroleum fractions in water is old in the art per se. These emulsions have been used in order to increase the quantity of certain additives in said petroleum fractions. Unfortunately, the results have been generally unsatisfactory particularly where the emulsions end use is in motor fuel compositions. One problem has been the unattractive, milky or opaque appearance of the emulsions. A more important failing has been the instability of the emulsion. For example, even the best emulsion eventually separates into two phases under stress and even under ideal storage conditions, some separation occurs within a relatively short time. The breaking of the emulsion is undesirable since it then becomes impossible to deliver homogenous fuel samples into the carburetor. Another problem of the prior art covering fuel-water emulsions has been that the surfactants are inherently corrosive to metals or have contained ash-forming metals. Furthermore, preparation of the emulsions of the prior art has required the use of high speed, high shear devices such as colloid mills and homogenizers.

Recently the inventors have developed a novel process of preparing stable, transparent water-in-oil emulsions, capable of dispersing substantially greater quantities of many water-soluble additives than can be dispersed in the neat petroleum fraction alone. Not only does the process enable the preparation of additive-rich dispersions but, in addition, the dispersions have viscosities similar to those of the petroleum fraction and thus, in the case of gasolines, they are readily carburetted. Also, they are perfectly clear to the eye for extended periods of time and utilize non-corrosive and ashless surfactants. In addition, the dispersions can be made using only moderate agitation such as is provided by conventional fuel blending equipment. This unique combination of properties was heretofore unobtainable and represents a significant advance in the art.

It is therefore an object of this invention, among others, to provide a novel process for preparing stable, clear, low-viscosity dispersions of petroleum fractions (such as gasoline or middle distillates) with water containing much greater quantities of water-soluble additives than has previously been possible.

It is a further object of this invention to provide stable, transparent, additive-rich "water-in-oil" emulsions which can be used as concentrates to incorporate substantial quantities of additives into petroleum fractions in which the additives are normally insufficiently soluble.

A specific object of this invention is the preparation of stable and clear gasoline compositions modified by the addition of water-soluble additives, said gasoline having increased octane numbers compared to the unmodified base fuel.

Additional objects will suggest themselves to those skilled in the art after a further reading of this application.

In practice, the above objects are achieved by a process wherein micro-emulsions comprising petroleum fractions and water are prepared using any of the procedures described below.

In one procedure an aqueous solution of the one or more water-soluble additives to be dispersed and an effective amount of at least one water soluble surfactant are added to the petroleum fraction preferably with brisk agitation. Then an effective amount of at least one petroleum fractionsoluble surfactant is incrementally added (titrated) to the agitated two phase system until a clear blend is produced. At this point a stable, clear, micro-emulsion of "water-in-petroleum" containing the surfactants, water, petroleum fractions and additives is formed in which the average particle diameter of the dispersed phase is 0.1 micron or smaller. These micro-emulsions can be used to achieve the objects of this invention. This procedure is particularly useful where the quantities of the two different surfactants required are unknown. The following represent alternative procedures.

In one alternative process the petroleum fraction to be emulsified is blended with the required quantities (as determined supra) of at least one petroleum-fractionsoluble surfactant and at least one water-soluble surfactant until a homogeneous mixture is obtained. Then an aqueous solution of the water-soluble additive or additives to be dispersed is added with agitation until a clear dispersion results. Again, the stability of the resultant microemulsions is as above.

Another alternative process is to prepare two separate blends, one of distillate containing the required amount of petroleum-fraction-soluble surfactant or surfactants, the other of water containing required amount water-soluble additive and water-soluble surfactants. Then the water blend is blended into the distillate blend until a clear micro-emulsion, identical in all its properties to those above, is prepared.

To further aid in the understanding of the invention, the following supplementary disclosure is submitted:

A. PETROLEUM FRACTIONS

As used throughout this disclosure, the term refers to fluid products derived from petroleum refining having an Initial Boiling Point range from about 21.degree. C (70.degree. F.) to an End Point of about 343.degree. C. (650.degree. F.) Illustrative fractions include middle distillates (such as gas oils, furnace oils, kerosene, diesel fuels) motor gasolines and aviation gasolines.

B. SURFACTANTS

1. HLB VALUE OF SURFACTANT

The term "HLB" value as used herein refers to the hydrophile-lipophile balance of a surfactant. That is, the relative simultaneous attraction that the surfactant demonstrates for water and oil. Substances having a high HLB, above about 12, are highly hydrophilic (and poorly lipophilic) while substances having a low HLB, below about 8, are lipophilic and consequently poorly hydrophilic. Those having an HLB between about 8 and 12 are intermediate. An extensive discussion of HLB can be found in the literature particularly in "Emulsions: Theory and Practice," by P. Becher, published by Reinhold Publishing Corp., N.Y., 1957.

2. PETROLEUM-FRACTION-SOLUBLE

As used throughout this application, refers to surfactants of the anionic, cationic or nonionic type. They must be both ashless upon ignition and soluble to the extent that at least a clear 10 percent by volume solution and preferably a clear 30 percent by volume solution of the surfactant can be prepared which is stable at 25.degree. C. An additional requirement is that when in the presence of both the petroleum fraction and water they are preferentially soluble in the petroleum fraction.

Illustrative petroleum fraction soluble surfactants include, among many others, the following materials sold under various proprietary means by different manufacturers; aliphatic esters of diethylene glycol such as diethylene glycol monolaurate, the mono and diesters of polyols such as sorbitol mono-palmitate, sorbitol monolaurate, polyoxyalkylated mono-di- and poly aliphatic esters of polyols such as mannitol dioleate, sorbitol monostearate, sorbitol monolaurate, as well as certain of the polyoxyalkylated alkylated phenols. In fact, the only limitation other than their solubility in petroleum fractions and freedom from ash-forming components is that the surfactants have hydrophile-lipophile balance (HLB) values, as outlined in the preceding section, in the range of about 3-10.

3. WATER-SOLUBLE SURFACTANTS

As used throughout this disclosure this term refers to surfactants of the anionic, nonionic or cationic type which must be ashless upon ignition and soluble in water to the extent that at least a clear 10 percent by volume solution and preferably at least a clear 30 percent by volume solution of the surfactant can be prepared which is stable at 25.degree. C. Furthermore, in the presence of both petroleum fraction and water, they are preferentially water-soluble.

Illustrative water-soluble surfactants include, among many others, the following materials sold under various proprietary names by different manufacturers; the fatty acid salts of polyalkanolamines, such as triethanolamine oleate, amine salts such as C.sub.21 tertiary alkyl primaray amine acetate and dodecylamine hydrochloride, quaternary ammonium salts such as soya trimethyl ammonium chloride, alkylated tertiary amine salts such as N-cetyl-N-ethyl morpholinium ethosulfate, as well as certain of the polyoxylated alkylated phenols, polyoxyalkylated alkyl ethers, polyoxyalkylated aliphatic esters of polyols, polyoxyalkylated aliphatic amines, alcohols, acids and amides. More specific illustrations of these polyoxyalkylated materials include nonyl phenol, stearyl, lauryl and oleyl amides, sorbitolmonooleate, sorbitol monolaurate, sorbitol monostearate and sorbitol monopalmitate, as well as stearyl, oleyl and tridecyl alcohols, all polyoxyethylated with from about 8-50 moles of ethylene oxide.

Again, the only limitation other than water solubility and freedom from ash is that the HLB value, as defined in the preceding section, be in the range of about 10-35.

It should be noted that the sole limitation on the use of the various "pairs" of surfactants, is that the use of cationic and anionic surfactants in the same dispersion are to be avoided since they usually tend to be incompatible.

C. WATER-SOLUBLE ADDITIVES

As indicated earlier, this term refers to various compounds of diverse structure which share in common: (a) that they have sufficiently good solubility in water to enable a clear 10 percent by weight solution of the additive to be prepared which is stable at 25.degree. C; (b) that they are insufficiently soluble in petroleum fractions (such as gasoline and middle distillate fractions) to change, enhance or otherwise favorably modify some property or characteristic of the petroleum fraction such as octane or cetane number, surface ignition properties, smoke formation, exhaust emissions or the like. Gasoline may contain octane improvers, antioxidants, metal deactivators and anti-icing agents among other types of additives.

The favored water-soluble additives which function especially well in this process and which form stable and clear dispersions are those selected from the group consisting of aliphatic diols, aliphatic amides, alkanolamines, polyamines and aliphatic aldehydes.

The additives particularly preferred are certain specific compounds of the group which have been found to increase octane numbers in motor fuels when they comprise from about 1 to 10 percent by volume or higher of the final fuel dispersion. These preferred additives are selected from the group consisting of formamide, acetamide, ethylene glycol, urea, ethylene diamine, propylene diamine, meta-phenyline diamine and formaldehyde.

D. CONCENTRATIONS AND RATIOS OF THE COMPONENTS

1. WATER

Ordinarily, the amount of water required to solubilize the water-soluble additive or additives to be used is the most important factor in determining the concentration of the other components. A minimal amount of water is employed depending upon the solubility of the additive in water and the amount of additive required to achieve the desired effect. In most instances the volume of water will make up from 0.5-30 percent of the final dispersion with the best results being obtained where the water makes up from 5-10 percent of the final dispersion volume.

2. ADDITIVES

The total parts by volume of additives employed per 100 parts by volume of micro-emulsion is a variable dependent upon several factors. These include the application for which the additive is employed, the cost of the additive, as well as the maximum amount of additive that can be dispersed in a given micro-emulsion prepared using a particular pair of surfactants. In many instances a range of from 0.1 to 10 parts by volume of additive per 100 parts by volume of the final microemulsion will suffice. More usually, a narrower range of 2 to 7 parts of additive per 100 parts by volume of microemulsion can be employed.

For example, to increase the octane number of gasoline, each 100 parts by volume of the final, clear gasoline composition will comprise:

a. from about 1 to 10 parts by volume additive,

b. from about 6 to 16 parts by volume of water,

c. from about 6 to 16 parts by volume of total surfactant, and

d. from about 87 to 58 parts by volume of the gasoline whose octane number is to be raised.

3. SURFACTANTS

The total amount of surfactant pairs required and the ratio of the two types to each other (high HLB, abbreviated as "H" and low HLB, abbreviated as "L") depends primarily on the amount of water, the nature of the additives and their concentration in the formulation as are discussed below:

a. Total amount of surfactant - Each surfactant may comprise as little as 1 part by volume or as much as 12 parts by volume. This range of quantities is referred to as an effective amount of surfactant.

b. Combined HLB of the surfactant pair - This is calculated by the following formula: ##EQU1##

The combined HLB of the surfactant pair may range from about 7 to 20, however, the best results are consistently obtained at 8-12 and for this reason this is preferred.

c. Ratio of H:L surfactants - Whatever the intended end use, it is critical that the proper ratio of hydrophilic (water soluble) surfactant to lipophilic (petroleum fractionsoluble) surfactant be used. The "H":"L" ratio is calculated as follows: ##EQU2##

In order to obtain the microemulsions of this invention, the calculated "H":"L" ratio should not be greater than about 6:1 and preferably from about 3:1 to 0.8:1. If a ratio of H:L substantially exceeds 6:1, the emulsions become either exceedingly viscous oil-in-water systems, if mixed by the procedure of Nixon, et al., or unstable mixtures if conventional, high speed mixing is used. In either case the products are completely unsuitable for the applications of this invention.

d. Petroleum fractions - these make up the major portion of the total dispersion volume and can comprise from 58 to 87 parts by volume of the dispersion. Ordinarily, from 70 to 80 parts by volume of the final dispersion are present as the petroleum fraction. Included in this category are the hydrocarbons present in conventional motor gasolines, kerosenes, furnace oils, diesel fuels and gas oils.

E. AGITATION

Whenever agitation is mentioned in the above procedures it is to be understood that conventional stirring or mixing equipment is satisfactory. In other words, no excessive shearing or high speed blending devices are necessary.

F. PREFERRED COMPOSITIONS

While the inventive process is fully operable to the extent disclosed, some more specific aspects of the inventive process produce the best results, and are therefore preferred.

As previously outlined, it has been found that if particular care is taken in the selection of the two types of surfactants, greatly improved results are obtained. For example, more favorable results are obtained when the distillate-soluble surfactant be selected from those having an HLB value from about 3-10 with the best results being when the petroleum fraction soluble surfactant has an HLB dispersion value from about 5-9.

Similarly, when the above-described petroleum fraction-soluble surfactants are used in conjunction with water-soluble surfactants having HLB values from about 10-35, superior results are obtained. This is particularly the case where a non-ionic water-soluble surfactant having an HLB value of from about 12-15 is used. If an anionic watersoluble surfactant is used, the preferred HLB range is 30-35. Thus the preferred process conditions of this invention are those in which at least one petroleum fraction-soluble surfactant having an HLB value of from 5-9 is used in conjunction with at least one non-ionic water-soluble surfactant whose HLB value is from 12-15, with the H/L (hydrophile-lipophile) ratio calculated as previously described is about 3:1 or less.

In order to disclose this invention in the greatest possible detail the following illustrative examples are submitted:

Unless specified otherwise, all temperatures are in degrees fahrenheit (.degree. F.) and all percentages or parts are by volume. In all instances the volatility characteristics such as IBP's and EP's are determined by ASTM D-86.

EXAMPLE 1 -

Preparation of an illustrative stable micro emulsion of unleaded base gasoline and water containing urea.

Procedure A -

A 10 parts by weight portion of urea (7.5 parts by volume) is dissolved into 68 parts by volume of water and 27 parts by weight (27.4 parts by volume) of [N-95, a nonylphenol ethoxylated with an average of 9.5 moles of ethylene oxide (HLB=12.5)] is stirred into the aqueous urea solution until a homogeneous solution is obtained. To 75 parts by volume of the vigorously stirred solution (containing 5.5 parts by vol. of urea, 49.5 parts by vol. water and 20.0 parts by vol. surfactant) is added 391 parts by volume of base gasoline (whose properties appear below),

Gravity API 59.3

Reid Vapor Pressure 9.2 lbs.

______________________________________ Distillation FIA Analysis (Fluorescent Indicator Analysis) ______________________________________ IBP -- 71.degree. F. 30.5% Aromatics EP -- 369.degree. F. 13.0% Olefins 56.5 Saturates ______________________________________

with continued stirring (when stirring is discontinued the mixture separates into 2 phases. A gasoline-soluble surfactant [N-40, a nonyl phenol ethoxylated with an average of 4 moles of ethylene oxide (HLB=9)] is then added in increments until a clear, transparent microemulsion is obtained. The total gasoline-soluble surfactant added is 34 parts by volume. The stable, clear, fluid microemulsion contains 1.1 percent by volume of urea whereas less than a 0.1% solution of urea in the neat base gasoline can be obtained using conventional dissolution procedures. The total HLB of the two surfactants is 11.2 and the H/L ratio is 2.4 to 1.

The same procedure is used to incorporate 1.5 percent by volume of urea using 14.1 percent by volume water, 4.1 parts by volume of water-soluble surfactant and 5.4 parts by volume of the gasoline-soluble surfactant. The HLB of the surfactants is 10.1 and the H/L ratio is 0.9 to 1.

Procedure B -

A 5.6 parts by volume portion of the gasoline-soluble surfactant of Procedure A (nonylphenol ethoxylated with 4 moles of ethylene oxide) is blended into 74.9 parts by volume of the unleaded base gasoline of Procedure A until a homogenous solution is obtained. Then a second blend is prepared by dissolving 10 parts by weight of urea (7.5 parts by volume) into 70 parts by weight of water (70 parts by volume) and adding to the stirred urea solution 20 parts by weight (20.3 parts by volume) of a water-soluble surfactant (nonylphenol ethoxylated with 9.5 moles of ethylene oxide). After the second blend becomes homogenous, 19.5 parts by volume are blended into the gasoline blend using vigorous agitation. After a short time a clear microemulsion is obtained, identical in all respects to the second emulsion prepared in Procedure A.

Procedure C -

A blend of the unleaded base gasoline of Procedure A is obtained by stirring 78.0 parts by volume of the gasoline and 4.0 parts by volume of the water soluble ethoxylated nonyl phenol of Procedure A and 6.8 parts by weight of the gasoline-soluble ethoxylated nonyl phenol of Procedure A, until a homogenous mixture is obtained. To the stirred mixture is slowly added 11.2 parts by volume of a 13.8 percent by weight (10.7 percent by volume) aqueous urea solution previously prepared. After the addition is complete a clear, microemulsion results. This is identical to the corresponding microemulsions prepared in Procedures A and B.

EXAMPLES 2-9 -

Preparation of micro-emulsions containing additional water-soluble additives.

In these examples Procedure A of Example 1 is used to formulate the micro-emulsions. The unleaded gasoline of Example 1 is used as the petroleum fraction. Three surfactants designated N-40, N-60 and N-95 are employed. N-40 is a nonylphenol ethoxylated with 4 moles of ethylene oxide and is a gasoline soluble surfactant. N-60 is nonylphenol ethoxylated with 6 moles of ethylene oxide and is also a gasoline soluble surfactant, while N- 95 is nonylphenol ethoxylated with an average of 9.5 moles of ethylene oxide and is a water-soluble surfactant. The concentrations of the water, gasoline, surfactant and additive components are shown in Table 1, which also lists the additives and surfactants used and the data from Example 1.

The figure in parenthesis following each surfactant is the proportion of the total HLB contributed by each surfactant. For example, in Table 1, Example 1, N- 95 contributed 7.9 and N-40 contributed 3.3 for a total HLB of 11.2. The H:L ratio in this case is 7.9/3.3 = 2.4 to 1.

TABLE 1 __________________________________________________________________________ PREPARATION OF MICROEMULSIONS Concentration (parts by volume) of Components of Emulsion Petroleum Com- Formu- Water-Soluble Addi- Water-Soluble Petroleum Fraction Fraction bined H:L lation Ex. Additive tive Surfactant Soluble Surfactant Water (1) HLB Ratio Procedure __________________________________________________________________________ 1 Urea 1.2 6.9 N-95 (7.9) 4.0 N-40 (3.3) 10.0 77.9 11.2 2.4:1 A,B,C 1.5 3.8 N-95 (4.7) 5.7 N-40 (5.4) 14.2 74.8 10.1 0.9:1 A 2 Ethylene Glycol 2.0 5.8 N-95 (6.8) 4.9 N-40 (4.1) 10.0 78.3 10.9 1.7:1 A 5.0 5.0 N-95 (7.9) 3.0 N-40 (3.4) 10.0 77.0 11.3 2.4:1 A 5.0 5.0 N-95 (7.9) 2.9 N-40 (3.3) 15.0 72.1 11.2 2.4:1 A 3 Formamide 1.0 4.2 N-95 (5.0) 5.4 N-40 (4.6) 10.0 78.4 10.6 0.0:1 A 1.0 N-60 (1.0) 2.0 4.2 N-95 (5.4) 5.5 N-40 (5.1) 10.0 78.3 10.5 1.1:1 A 5.0 2.5 N-95 (4.7) 4.1 N-40 (5.7) 10.0 78.4 10.4 0.8:1 A 4 Acetamide 4.4 4.2 N-95 (5.1) 6.0 N-40 (5.3) 10.0 75.4 10.4 1:1 A 5 Ethanolamine(mono) 2.0 5.0 N-95 (7.0) 4.0 N-40 (4.0) 10.0 79.0 11.0 1.8:1 A 5.0 6.5 N-95 (9.2) 2.3 N-40 (2.4) 9.9 76.4 11.6 3.8:1 A 6 Ethylene Diamine 2.5 5.5 N-95 (8.5) 2.6 N-40 (3.1) 10.5 78.9 11.6 2.7:1 A 7 Propane Diamine 5.0 8.5 N-95 (9.9) 1.6 N-40 (1.3) 10.0 74.3 11.8 5.2:1 A 0.6 N-60 (0.6) 8 m-Phenylene Diamine 1.0 4.2 N-95 (5.3) 5.0 N-40 (4.9) 9.9 79.9 10.2 1.1:1 A 9 Formaldehyde 4.2 3.0 N-95 (4.2) 6.0 N-40 (6.0) 6.8 80.0 10.2 0.7:1 A 5.7 4.4 N-95 (6.0) 4.8 N-40 (4.7) 15.2 69.9 10.7 1.3:1 A __________________________________________________________________________ .sup.(1) Gasoline in Examples 1-9

EXAMPLES 10-14 -

Preparation of micro-emulsions of gasoline and water containing ethylene glycol using other surfactant pairs.

In these examples micro-emulsions of gasoline and water containing ethylene glycol are prepared using Procedure A of Example 1. Table 2 shows the concentrations of the micro-emulsion components as well as the total HLB, the individual HLB and the H:L ratio of the surfactant pairs used. All of the blends are clear fluids of low viscosity.

EXAMPLES 15-16 -

The preparation of micro emulsions using other petroleum fractions.

Using the blending technique of Procedure A, microemulsions are prepared using No. 2 Diesel Fuel and Kerosene as the petroleum fraction, ethylene glycol as the additive and ethoxylated nonylphenols as the surfactant pairs. In all instances clear and stable micro-emulsions are produced. Compositions are shown in Table 2.

TABLE 2 __________________________________________________________________________ PREPARATION OF MICROEMULSIONS USING VARIOUS SURFACTANT PAIRS Concentration (parts by volume) of Components of Emulsion Petroleum Com- Pro- Water-Soluble Addi- Water-Soluble Petroleum Fraction Fraction bined H:L ce- Ex. Additive tive Surfactant Soluble Surfactant Water (1) HLB Ratio dure __________________________________________________________________________ 10 Ethylene Glycol 5.0 4.2 NH.sub.4 Lauryl Sulfate(12.7) 6.0 N-40 (5.3) 10.8 74.0 18.0 2.4:1 A 11 Ethylene Glycol 5.0 2.0 Triethanol- amine Lauryl Sulfate (6.8) 10.0 N-40 (7.2) 10.0 73.0 14.0 0.9:1 A 12 Ethylene Glycol 5.0 5.0 C.sub.21 t-Alkyl- primary Amine Acetate* 6.0 N-40 10.0 74.0 * * A 13 Ethylene Glycol 5.0 3.0 Ethanolamine Octyl Ortho- phosphate* 9.0 N-40 12.0 71.0 * * A 14 Ethylene Glycol 5.0 6.0 Tween 40 (8.5) 5.0 SPAN 20(3.9) 10.0 74.0 12.4 2.2:1 A 15 Ethylene Glycol 5.0 5.0 N-95 (5.7) 6.0 N-40 (4.9) 10.0 74.0 10.6 1.1:1 A 16 Ethylene Glycol 5.0 4.8 N-95 (5.7) 5.6 N-40 (4.9) 10.0 74.6 10.6 1.1:1 A __________________________________________________________________________ (1)Diesel fuel (IBP-375.degree.F; EP-600.degree.F) used in Example 14; Kerosene (IBP-330.degree.F; EP-515.degree.F) used in Example 15. All others used Gasoline. * Since the HLB of one of the surfactants is not known, the combined HLB and H:L ratio are not shown.

In related work the blending procedure of Examples 15 and 16 is followed using the same quantities of water, ethylene glycol and the same surfactant pairs except that No. 1 Diesel Fuel is substituted for kerosene on a volume-for-volume basis. A satisfactory micro-emulsion is obtained. Boiling ranges for the above petroleum fraction are as follows:

Petroleum Fraction IBP EP ______________________________________ No. 1 Furnace Oil 350 525 No. 2 Furnace Oil 375 625 Kerosene 330 500 ______________________________________

EXAMPLES 1, 3, 5, 7 and 18 to 25 -

Establishing criticality of "H":"L" ratio

The compositions in these examples, shown in Table 3, cover H:L ratios from 0.8 to 1 to 38 to 1. They include five different water-soluble additives, four different additive pairs and two petroleum fractions. It will be seen that at an H:L ratio of 7:1, the clear, fluid compositions of the present invention were not obtained, while at ratios of from 0.8 to 1 to 5.2 to 1 the desired fluid, clear microemulsions were obtained. Thus it is evident that an H:L ratio of less than about 7 is critical to the formation of the compositions of this invention.

The emulsions were judged by appearance while the type (water in petroleum or petroleum-in-water) of emulsion was determined by electrical conductance* to see if the desired satisfactory water in petroleum fraction type was obtained. As shown in Table 3, satisfactory water-in-petroleum emulsions can only be achieved when the combined HLB is below about 12 and the "H" to "L" ratio is at least 0.8:1 to 5.2:1, preferably from 1:1 to about 4:1.

TABLE 3 __________________________________________________________________________ EXAMPLES SHOWING CRITICALITY OF H/L RATIO Concentration (parts by volume) of Components of Emulsion Water-Soluble Water-Soluble Petroleum Fraction Petroleum Ex. Additive Additive Surfactant Soluble Surfactant Water Fraction __________________________________________________________________________ 3 Formamide 5.0 2.5 N-95 (4.7) 4.1 N-40 (5.7) 10 78.4 Gasoline 1 Urea 1.5 3.8 N-95 (4.7) 5.7 N-40 (5.4) 14.2 74.8 Gasoline 18 Ethylene Glycol 2.0 6.0 N-95 (5.8) 7.0 N-20 (3.2) 10.0 75.0 JP-4 19 Ethylene Glycol 2.0 6.0 N-95 (6.3) 6.0 SPAN 80 (2.2) 10.0 76.0 JP-4 20 Ethylene Glycol 2.0 5.0 Tween 80 (7.5) 5.0 SPAN 80 (2.2) 10.0 78.0 JP-4 5 Ethanolamine(mono) 2.0 6.4 N-95 (9.2) 2.3 N-40 (2.4) 9.9 76.4 Gasoline 7 Propane Diamine 5.0 8.5 N-95 (9.9) 1.6 N-40 (1.3) 10.0 74.3 Gasoline 0.6 N-60 (0.6) 17 Ethylene Glycol 2.0 6.0 N-95 (10.4) 1.2 N-40 (1.5) 10.0 80.8 JP-4 21 Formamide 1.14 1.44 Tween 80 (10.8) 0.56 SPAN 80 (1.2) 0.86 96.0 JP-4 22 Formamide 1.14 1.62 Tween 80 (12.1) 0.38 SPAN 80 (0.8) 0.86 96.0 JP-4 23 Ethylene Glycol 2.5 4.0 Tween 80 (12.1) 1.0 SPAN 80 (0.8) 2.5 90.0 JP-4 24 Ethylene Glycol 2.0 8.0 Tween 80 (12.0) 2.0 SPAN 80 (0.8) 10.0 78.0 JP-4 25 Ethylene Glycol 1.0 1.36 Tween 80(13.65) 0.14 SPAN 80 (0.36) 1.0 96.0 JP-4 __________________________________________________________________________ Combined Emulsion Emulsion Yield Stress Mixing Ex. HLB H:L Ratio Type Appearance Dynes/cm.sup.2 Procedure __________________________________________________________________________ 3 10.4 0.8:1 w/o Clear liquid 0 (1) 1 10.1 0.9:1 w/o Clear liquid 0 (1) 18 9.0 1.8:1 w/o Clear liquid 0 (1) 19 8.4 2.9:1 w/o Clear liquid 0 (1) 20 9.7 3.5:1 w/o Clear liquid 0 (1) 5 11.6 3.8:1 w/o Clear liquid 0 (1) 7 11.8 5.2:1 w/o Clear liquid 0 (1) 17 11.9 7:1 o/w Gel 2000 (2) 21 12.0 9:1 o/w Gel 1900 (2) 22 12.9 15:1 o/w Gel 3550 (2) 23 12.9 15:1 o/w Gel 850 (2) 24 12.8 15:1 o/w Gel 2000 (2) 25 14.0 38:1 o/w Gel 1200 (2) __________________________________________________________________________ (1) Microemulsion formed with conventional stirring. (2) Gel forms using mixing procedure of Nixon, et al. Otherwise, no emulsion.

EXAMPLES 26-34 -

Engine tests on the gasoline-in-petroleum micro-emulsions of Examples 1-9.

Comparisons were made in terms of octane number between the transparent motor fuel compositions (microemulsions) of Examples 1 to 9 and the unleaded base fuel used as the gasoline stock in Examples 1 to 9. A Research ASTM D-908-47T (CFR Engine) Method was used and the testing procedure of ASTM Operating Conditions was 600 rpm and 125.degree. F. intake air temperature. The engine operated unthrottled with carburetted fuel supply. Controlled operating parameters were speed, intake air temperature, intake air humidity, compression ratio, mixture strength and spark timing. Table 4 summarizes the data.

As can be seen from Table 4, increases in octane numbers ranging from 1.7 to 9.6 units can be obtained over base fuel containing the same quantities of water.

Table 4 __________________________________________________________________________ Engine Tests on Emulsions from Examples 1 to 9 % by Vol. % by Vol. % by Vol. Ex. Formulation Water-Soluble Additive in Water in of Total Research Octane (1) Additive Formulation Formulation Surfactants Octane Number Increase __________________________________________________________________________ -- Base Fuel None -- -- -- 93.3 -- -- Base Fuel None -- 10 9.6 94.7 1.4 -- Base Fuel None -- 15 10.5 96.3 3.0 26 Example 1 Urea 1.2 10.0 10.8 96.0 1.3 " " " 1.5 14.0 9.5 99.1 2.8 27 Example 2 Ethylene glycol 2.0 10.0 10.7 98.0 3.3 " " " 5.0 10.0 8.0 98.8 4.1 " " " 5.0 15.0 7.9 103.0 6.7 28 Example 3 Formamide 1.0 10.0 10.6 96.1 1.4 " " " 2.0 10.0 9.7 101.8 7.1 " " " 5.0 10.0 6.6 101.6 6.9 29 Example 4 Acetamide 4.4 10.0 10.2 97.4 2.7 30 Example 5 Ethanolamine 2.0 10.0 9.0 97.9 3.2 " " " 5.0 9.9 8.7 98.9 4.2 31 Example 6 Ethylenediamine 2.5 10.5 8.1 104.3 9.6 32 Example 7 Propanediamine 5.0 10.0 10.7 99.2 4.5 33 Example 8 m-phenylene-diamine 1.0 9.9 9.2 98.5 3.8 34 Example 9 Formaldehyde 4.2 6.8 9.0 96.5 1.8 " " " 5.7 15.2 9.2 99.6 3.3 __________________________________________________________________________ (1) Octane increase above fuel level without water-soluble additive.

As the preceding specification has demonstrated, several advantages accrue from the practice of this invention, both in the process and product aspects.

For example, the inventive process provides a simple, reproducible method of increasing the quantity of normally poorly soluble additives that can be incorporated into gasolines and middle distillates such as diesel fuels, automotive fuels and aviation fuels. In a more specific vein, the process of this invention provides an alternative means of upgrading the cetane or octane numbers of the above distillates using readily available, and easily handled additives. It also provides a means of incorporating water in fuels in an extremely stable form without the necessity of using any equipment other than conventional blending devices.

In its product aspect this invention provides stable and clear micro-emulsions of distillate fractions and water which incorporate greater quantities of additives than has been heretofore possible to solubilize in the neat distillate. In its more specific product embodiment this invention provides gasoline-additive compositions that have substantially improved octane numbers compared to the untreated gasolines.

This invention is also advantageous over the closest known art. U.S. Pat. No. 3,458,294 (Nixon et al.) who discloses processes of preparing emulsions of liquid hydrocarbon containing major amounts of liquid hydrocarbon and as a continuous phase a minor portion of polar organic liquid including minor amounts of additives. Some salient differences between the claimed invention and Nixon et al. are:

a. The applicants always utilize water, Nixon may or may not.

b. We require at least two surfactants, Nixon may use one.

c. Applicants' compositions are water-in-petroleum fraction type emulsions while the patentees' are petroleum fraction-in-water type emulsions.

d. Our compositions have viscosities close to that of the petroleum fraction phase (zero yield value). Nixon's are grease-like compositions having yield stresses of from 850 dynes/cm.sup.2 (see composition b, Table VII) to 3550 dynes (composition C, Table VI).

e. Our blending process is essentially independent of the order of addinv the components or the type of mixing employed. In contrast, unless the order of addition and type of mixing, both disclosed in Nixon, are used, the desired type of product is not obtained.

f. Finally, in applicants' claimed process, unless the critical ratio of hydrophilic surfactant to lipophilic surfactant (less than 6:1, preferably from about 3:1 to 0.8:1) is utilized, the desired results are not obtained. That is, above 6:1 leads to the formation of either very viscous, gel-like emulsions or no emulsions, depending on the mixing technique.

Finally, this invention is advantageous in that numerous modifications, substitutions and changes can be made in both its process and product aspects without departing from the inventive concept. The metes and bounds of this invention are best determined by the claims which follow, read in conjunction with the specification.

Claims

What is claimed is:

1. A stable, clear motor gasoline composition having substantially higher octane numbers than unmodified base fuels consisting essentially of an admixture of the following components in the proportions indicated:

a. from about 58 to 87 parts by volume of gasoline,

b. from about 6 to 16 parts by volume of water,

c. from about 3 to 8 parts by volume of at least one gasoline-soluble surfactant having an HLB value from about 5 to 9, said surfactants selected from the group consisting of diethylene glycol monolaurate, sorbitol monopalmitate, sorbitol monolaurate, polyoxyalkylated mannitoldiolate, polyoxyalkylated sorbitrol monostearate, polyoxyalkylated sorbitol monolaurate and polyoxyalkylated alkylated phenols,

d. from about 3 to 8 parts by volume of at least one water-soluble surfactant having an HLB value from about 10 to 35, selected from the group consisting of C.sub.21 tertiary alkyl primary amine acetate, dodecylamine hydrochloride, ammonium lauryl sulfate, triethanolamine sulfate, ethanolamine octyl ortho phosphate, polyoxyalkylated nonyl phenol, polyoxyalkylated stearyl amides, polyoxyalkylated lauryl amides, polyoxyalkylated oleyl amides, polyoxyalkylated sorbitolmonooleate, polyoxyalkylated sorbitol monolaurate, polyoxyalkylated sorbitol monostearate, polyoxylated sorbitol monopalmitate, polyoxyethylated stearyl alcohol, polyoxyethylated oleyl alcohol and polyoxyethylated tridecyl alcohol,

e. from about 0.5 to 10 parts by volume of a water-soluble, insufficiently gasoline-soluble, additive selected from the group consisting of acetamide, formamide, monoethanolamine, ethylene diamine, propane diamine, and m-phenylene diamine, said parts by volume ratio of water-soluble surfactant petroleum fraction-soluble surfactant do not exceed about 5:1.

2. The fuel composition of claim 1 wherein the additive is ethylene glycol.

3. The fuel composition of claim 1 wherein the additive is formamide.

4. The fuel composition of claim 1 wherein the additive is ethanolamine.

5. The fuel composition of claim 1 wherein the additive is ethylene diamine.

6. The fuel composition of claim 1 wherein the additive is urea.

7. The fuel composition of claim 1 wherein the additive is acetamide.

8. The fuel composition of claim 1 wherein the additive is propane diamine.

9. The fuel composition of claim 1 wherein the additive is m-phenylene diamine.

10. The fuel composition of claim 1 wherein the additive is formaldehyde.