JPH04234492A - Micro-emulsion diesel fuel composition and method of using it - Google Patents

Abstract

PURPOSE: To provide a fuel composition having improved combustion efficiency and reduced smoke, soot and NO_x, etc., emissions by blending a diesel fuel with respectively specific amounts of water, a 1-3C alkanol, an additive such as inorganic oxidizing agents, and a surfactant system having specific compositions.

CONSTITUTION: The fuel composition is prepared by blending (A) a diesel fuel with (B) about 1-30 wt.% of water based on component A, (C) about 0-30 wt.% of a 1-3C alkanol based on component B, (D) about 20 wt.% or less, based on component B, of an additive selected from inorganic oxidizing agent, polar organic oxidizing agents, and nitrogen oxide-containing compounds (e.g. ammonium nitrate), and (E) about 0.5-15 wt.%, based on component A, of a surfactant system which comprises a balanced blend of a hydrophilic surfactant and a lipophilic surfactant in proportions sufficient to form single-phase, translucent microemulsions. Thus, the cetane number can be improved when the diesel fuel burns in a diesel engine, and the emissions of CO and the like can be reduced.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to novel microemulsion formulations that are clear, thermodynamically stable fluids useful in reducing diesel exhaust emissions. A wide variety of microemulsion fuel formulations are known to those skilled in the art. Their disadvantage is a lack of stability under the conditions to which the fuel is exposed. For example, prior art formulations are unstable and prone to demulsification at high and low temperatures, and demulsification at high temperatures is particularly problematic. Furthermore, in prior art formulations that do not contain alcohol, exposure to salt-laden air or water causes significant demulsification problems even when minimal amounts of salt are added. Another disadvantage of prior art microemulsion fuel formulations is the high concentration of surfactants required to form the microemulsion. Generally, prior art inventions use more than one part surfactant per part water to be solubilized.

The microemulsions of the present invention provide improved temperature and salt stability and seek to overcome the aforementioned disadvantages by using low concentrations of surfactants. The present invention provides translucent, thermodynamically stable diesel fuel formulations with improved combustion efficiency and reduced smoke, dust, CO and NOX emissions. A diesel fuel formulation includes diesel fuel, water or an aqueous solution of a low molecular weight alcohol and/or a water-soluble reagent, and a surfactant system comprising an equilibrium blend of one or more hydrophilic surfactants and one or more lipophilic surfactants. The diesel fuel formulation may contain as much as 30% by weight of an aqueous phase with an aqueous phase/surfactant ratio of at least 2/1.

[0003] The translucent, thermodynamically stable microemulsion formulations of the present invention are formulated using hydrocarbon fuels such as gasoline, jet fuel, or diesel fuel (preferred); water;
From compounds containing 0 to 30% by weight of C1-C3 alkanols, based on the amount of water, and less than 20% by weight, based on the amount of water, of ash-free inorganic oxidizing agents, low molecular weight polar organic oxidizing agents, and nitrogen oxides. ammonium nitrate, ammonium nitrite, hydrogen peroxide, ammonium hypochlorite, ammonium chlorite, ammonium perchlorate, ammonium chlorate, perchloric acid, chlorous acid, hypochlorous acid, Ammonium bromate, ammonium bromite, hypobromite, bromic acid, ammonium hypoiodite, ammonium periodate, hypoiodite, iodic acid, periodic acid,
2,4-dinitrophenylhydrazine, 2,5-dinitrophenol, 2,6-dinitrophenol, 2,4-
Dinitroresorcinol, nitroguanidine, 3-nitro-1,2,4-triazole, 2-nitroimidazole, 4-nitroimidazole, priculic acid, cumene hydroperoxide, cyanuric acid, nitroglycerin, nitrobenzene, trinitrotoluene, and mixtures thereof. from about 1 to about 30% by weight, more preferably from about 2 to about 20%, most preferably from about 2 to about 15% by weight of an aqueous formulation comprising one or more additives selected from the group consisting of;
and a surfactant system comprising an equilibrium blend of one or more hydrophilic surfactants and one or more lipophilic surfactants.
from about 15% by weight, more preferably from about 1 to about 10%, most preferably from about 1 to about 5%, with an aqueous formulation/surfactant system ratio of at least 2/1.

Systems in which water and/or C1 or C2 alkanol are dispersed in diesel fuel produce smoke, soot, dust,
It is known to those skilled in the art to reduce harmful diesel emissions such as and NOX. Due to the presence of water and alkanols in diesel fuel, a significant reduction in cetane number and significant ignition delay often requiring modification of engine and/or working parameters such as adjustment of ignition time or installation of preheating plugs. It is also known to cause The novel formulations of the present invention offset the aforementioned disadvantages while retaining the advantage of reducing emissions through the addition of oxidizing agents and/or nitrogen reagents to aqueous formulations.

In the practice of this invention, at least one hydrophilic surfactant and at least one lipophilic surfactant are selected, the proportions of which are such that they form a single phase with the fuel and aqueous formulation. The combination of hydrophilicity and lipophilicity is tailored to form a transparent microemulsion. The hydrophilic surfactant is a fuel (oil) in the microemulsion phase when an equal blend of a fuel and an aqueous formulation containing 2 g of said surfactant per deciliter of liquid is used.
The microemulsion of the lower phase has a volume ratio (VO /VS ) to surfactant of at least 0.5, preferably greater than 1, and more preferably greater than 2.
It is defined by a series of effects formed at °C. The term "lower phase" microemulsion refers to the aforementioned system containing a hydrophilic surfactant and an equal blend of fuel and aqueous formulations containing an excess of fuel (oil) that is substantially free of surfactant. ) describes a situation in which a lower aqueous phase separates into a lower aqueous phase containing most of the surfactant in equilibrium with the surfactant.

Hydrophilic surfactants as defined by the foregoing properties include, but are not limited to, salts of alkyl carboxylic acids and alkylaryl sulfonic acids. However, the alkyl group in the compound is a C9 to C18 linear, branched or bilinear structure, the aryl group is selected from benzene, toluene, orthoxylene, and naphthalene, and the salt is selected from an alkali metal, ammonia, or an alkanol. It is an amine salt. Ethoxylated alkylphenols are also included and preferred. Most preferred are ethoxylated C12 to C18 alkylcarboxylic acids and alkylarylsulfonic acids containing six or more ethylene oxides (hereinafter abbreviated as EO), in which the alkyl and aryl groups are as defined above. It is an alkylammonium salt.

Representative examples of hydrophilic alkyl carboxylic acids and alkylaryl sulfonates include monoethanol ammonium laurate, ammonium palmitate, diethanol ammonium stearate, monoethanol ammonium nonyl o-xylene sulfonate, and sodium dodecylbenzel sulfonate. , ammonium tetradecylbenzene sulfonate, diethanolammonium hexadecylbenzene sulfonate, and sodium dodecylnaphthalene sulfonate. Preferred hydrophilic carboxylic acid salts include monoethanol ammonium oleate, penta-, deca-, and hexadeca-ethoxyoctadecyl ammonium oleate. Preferred hydrophilic sulfonate salts include penta- and deca-ethoxyoctadecylammonium benzene sulfonates (C12BS-E18-5 and C12BS-E, respectively).
18-10), heptaethoxyoctadecylammonium dodecyl O-xylene sulfonate (C12X
S-E18-7) and decaethoxyoctadecylammonium dodecyl o-xylene sulfonate (C1
2XS-E18-10). Ethoxylated alkyl amines used in the preparation of ethoxylated alkylammonium salts of alkylaryl sulfonic acids are commercially available from Exxon Chemical and Performance Products.
Products), Toma Products
r Products).

Representative hydrophilic ethoxylated alkylphenols include Igepal® DM710, Igepal® DM730, available from GAF.
, and Igepal® DM880 (chemically dinonylphenol ethoxylated with 15, 24, and 49 moles of EO, respectively). It is dinonylphenol ethoxylated with 9 moles of ethylene oxide. Igepal® DM530 is preferred. Other suitable ethoxylated alkylphenols include Rohm, Philadelphia, Pennsylvania;
Tritons® X100, X10 available from Rohm and Haas
2, and X114, and Igepal CO610,
630, 660, 710, 720, 730, 850, and 880 (chemically monooctyl or nonylphenol ethoxylated with 8 to 30 moles of EO).

The lipophilic surfactant for this invention has a concentration of 2 g/d in an equal blend of fuel and aqueous formulations.
The microemulsion in the upper phase is such that the volume ratio of water to surfactant in the microemulsion phase (VW/Vs) is at least 0.5, preferably greater than 1, and most preferably greater than 2 when 1. It is a surfactant with properties that it provides at ℃. The term “upper phase” used to define lipophilic surfactant components
The term microemulsion refers to a system in which a surfactant is present in an equal blend of fuel and aqueous formulations in equilibrium with an excess aqueous phase that is substantially free of surfactant. Separation into the upper phase of the containing oil.

Lipophilic surfactants defined by the foregoing properties include, but are not limited to, ethoxylated alkylphenols. Salts of alkyl carboxylic acids and alkylaryl sulfonic acids are also included and preferred. however,
The alkyl groups in the compound are C12 to C24 linear, branched, or bilinear structures, the aryl groups are selected from benzene, toluene, orthoxylene, and naphthalene, and the salts are selected from alkali metals, ammonia, or alkanolamines. It's salt. C9 to C24 where the alkyl and aryl groups are as defined above and contain less than 6 EOs
Ethoxylated C12 to C18 alkylammonium salts of alkylcarboxylic acids and alkylarylsulfonic acids are more preferred.

Representative examples of lipophilic alkylaryl sulfonates include monoethanol ammonium dodecyl o
-Xylene sulfonate, sodium tetradecyl O-
xylene sulfonate, sodium hexadecyl o-xylene sulfonate, diethanolammonium pentadecyl o-xylene sulfonate, triethanolammonium octadecyl o-xylene sulfonate (prepared from penta and hexapropylene), sodium octapropylene benzene sulfonate, sodium tetracosyl toluene sulfonate, and various high molecular weight petroleum sulfonates. Preferred are the sodium and monoethanolammonium salts of dodecyl o-xylene sulfonic acid. diethoxyoctadecyl ammonium oleate, di- and penta-ethoxyoctadecyl ammonium dodecyl o-xylene sulfonate (E1
8-2 oleate, C12XS-E18-2 and C12
XS-E18-5) is most preferred.

Representative lipophilic ethoxylated alkylphenols include Igepal CO210 and C
O430, and Tritons® X1, an octylphenol containing 1 and 3 moles of EO, respectively.
5 and X35. The present invention is not limited to the use of the above-mentioned ethoxylated alkylphenols, but can be expressed by the general formula: R1X(CH2CH2O)n Y (wherein R1 is alkyl or mono- or di- is an alkylaryl group, and X is -O-, -S-, -NR3H-, -NR2-,
[-NR2-]+ Cl-, -CO-O-, -CO
-OR4O-, -CO-NH- or -SO2NH -, and Y is -H-, -SO2 -M+ or -(PO3
H)-M+ (where M+ is an ammonium cation including an inorganic or alkyl-substituted ammonium cation); R2 is an alkyl group containing 1 to 20 carbon atoms or an (CH2CH2O) group containing 1 to 30 R3 is H or an alkyl group containing 1 to 3 carbon atoms; R4 is a polyhydroxyl group derived from glycerol, glycol, sorbitol, or various sugars; n is It is an integer from 1 to 30. ) also includes other ethoxylated surfactants.

The above-mentioned ethoxylated alkylphenol is
General formula: R-SO3H (where R in the formula is an alkyl or alkylbenzene group containing 8 to 30 carbon atoms in the alkyl chain, and the benzene ring is an alkyl group containing 1 to 3 carbon atoms) Equilibrium blends of surfactants are blended with alkali metal, ammonium, alkylammonium, alkanol ammonium, or ethoxylated alkylammonium salts of alkyl or alkylaryl sulfonic acids (optionally substituted with one or two groups). can be provided. Preferred blends of ethoxylated alkylphenols and alkylaryl sulfonates include Igepal® DM530 or Igepal® DM7.
10 and the sodium or monoethanolamine salt of C12o-xylene sulfonic acid.

Alternatively, ethoxylated alkylammonium salts of the aforementioned alkylarylsulfonic acids of varying degrees of ethoxylation may be blended to provide an equilibrium blend of surfactants. Preferred blends of ethoxylated alkylammonium salts of alkylaryl sulfonic acids include a combination of heptaethoxyoctadecyl ammonium dodecylbenzenesulfonate and pentaethoxyoctadecyl ammonium dodecylbenzenesulfonate and decaethoxyoctadecyl ammonium dodecyl O-xylene sulfonate and diethoxycocoammonium dodecyl o - xylene sulfonate combinations. hepta or decaethoxyoctadecyl ammonium dodecyl o
- a blend of xylene sulfonate and pentaethoxyoctadecyl ammonium dodecyl o-xylene sulfonate, i.e. C12XS-E18-5 and C12XS
-E18-10 is most preferred.

Alternatively, alkali metal, ammonium, alkylammonium, alkanol ammonium alkylcarboxylic acids of the general formula: R'-COOH (wherein R' is an alkyl group having 12 to 20 carbon atoms) Alternatively, ethoxylated alkylammonium salts may be used in place of the aforementioned sulfonate salts. These salts can be blended with ethoxylated alkylphenols. Alternatively, ethoxylated alkyl ammonium salts of the aforementioned alkyl carboxylic acids that are ethoxylated to varying degrees can be blended to provide an equilibrium blend of surfactants. Most preferred are blends of decaethoxyoctadecyl ammonium oleate and pentaethoxyoctadecyl ammonium oleate, ie, blends of E18-10 oleate and E18-5 oleate.

Under certain circumstances, the presence of up to 20% by weight, typically 2 to 10% by weight, of a cosurfactant in a surfactant blend improves the solubility of the surfactant in the fuel; The viscosity of microemulsion diesel fuel formulations is reduced. Cosurfactants include alkyl glycol monoalkyl ethers, C4 to C6 alkanols, and mixtures thereof. Typical cosurfactants include ethylene glycol monopropyl ether, methylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethyl glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol n-butyl ether, and propylene glycol. Included are ethers such as monomethyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether, and linear and branched alkanols such as butanol and pentanol. Among the alkanols, t-amyl alcohol (TAA) is preferred. Among the ethers, ethylene glycol monobutyl ether is preferred.

It will be appreciated that if a co-surfactant is used, the surfactant proportions must be readjusted with respect to the change in phase behavior brought about by the addition of the co-surfactant. It will also be appreciated that the weight ratio of hydrophilic surfactant to lipophilic surfactant must be readjusted for changes in phase behavior brought about by different aqueous reagents and changes in their concentrations. For example, increasing the concentration of the aqueous reagent ammonium nitrate requires increasing the ratio of hydrophilic surfactant to lipophilic surfactant. Similarly, changes in the composition of the fuel will require readjustment of the surfactant proportions. For example, as the concentration of aromatic hydrocarbons in the fuel increases, it becomes necessary to increase the ratio of hydrophilic surfactant to lipophilic surfactant. It is also understood that selection of hydrophilic surfactant pairs (e.g., more or less degree of ethoxylation) may be required if changes in surfactant proportions are insufficient to compensate for changes in the fuel or aqueous formulation. It will be. These points will be clarified by the examples described below. The preferred surfactant blends of the present invention are significantly improved over the prior art because they greatly increase the solubility in the aqueous phase per unit amount of surfactant over the prior art. Prior art includes
Diesel fuel microemulsions containing less than twice the amount of water relative to the volume of surfactant are disclosed. The examples described below disclose formulations having 2 to 4 times the amount of aqueous phase relative to the volume of surfactant.

The most preferred surfactants of the present invention have the general formula:

[0019]

[Chemical formula 1]

(However, R1 and R3 in the formula are paraffinic or olefinic alkyl groups containing 8 to 24 carbon atoms, R2 is a methyl group or a benzene, toluene, or xylene ring, and m+n is 2 to 20, and X- is -COO- or SO3-
It is. ) is selected from group 1. Representative, non-limiting examples of Group 1 surfactants include ethoxylated octadecylammonium dodecylbenzenesulfonate (C12BS-E18-(n+m), where R1=C18H37, R3=C12H25, R2=C
6H4, and X- = SO3 - ); ethoxylated octadecyl ammonium dodecyl xylene sulfonate (
C12XS-E18-(n+m), where, R1=
C18H37, R3=C12H25, R2=(CH3)
2C6H2, and X- = SO3 - ); and ethoxylated octadecylammonium oleate (E18-(
n+m) oleate, provided that in the formula R1=C18H37,
R3-R2=CH3(CH2)7CH=CH(CH2
)7, and X−=COO−).

Other most preferred surfactants have the general formula:

[0022]

[Case 2]

(However, R3 and R2 in the formula are defined in the same manner as in Group 1, and X is 3.) Representative, non-limiting examples of Group 2 surfactants include monoethanolammonium dodecylbenzenesulfonate (C12BS-M
EA), monoethanolammonium dodecylxylene sulfonate (C12XS-MEA), diethanolammonium pentadecylbenzenesulfonate (C15
XS-DEA), ammonium oleate and monoethanol ammonium oleate.

It has been found that it is often advantageous to blend Group 1 surfactants with Group 2 surfactants to form an equilibrium blend of hydrophilic and lipophilic surfactants. It has been discovered that Group 1 surfactants become more lipophilic with increasing temperature, and Group 2 surfactants also become more hydrophilic with increasing temperature. It has also been discovered that blends of Group 1 surfactants and Group 2 surfactants form microemulsions that are more stable to phase separation than microemulsions previously found to those skilled in the art over a wide temperature range. This reduced temperature sensitivity is a highly desirable feature of Applicants' most preferred diesel fuel microemulsions. When stored for a period of time, diesel fuel may be exposed to wide temperature changes. While conventional microemulsified diesel fuels phase separate under these conditions, the most preferred fuel microemulsion formulations of the present invention are stable. [Example I] Preparation of anion-ethoxy cation complex 1
Weigh 00 g of alkyl carboxylic acid or alkylaryl sulfonic acid into a jar. Add the appropriate amount of ethoxylated alkylamine as shown in Table 1 and stir vigorously (warm due to heat of neutralization). properties, neutralization weight,
and chemical feeds are shown in Table 1.

[Table 1] Preparation of anion-ethoxy cation complex Components
Average molecular weight Weight % of active ingredient Equivalent oleic acid in 100g
282 100
0.354C12BSH (Vista SA 59
7) 326
-98 0.3361 C12XSH(
ESSAF SA 149)
354 -81 0.2
261 C18N(EO)2(Tomah E18-2
)a 357 -98
0.275C18N(EO)5(To
mah E18-5) b 489
-98 0.200C18
N(EO)10(Tomah E18-10)c
709 -98
0.138C18N(EO)15(Tomah E1
8-15) d 929 -
98 0.105MEA (monoethanolamine) 61 10
0 1.639
Weight of amine in 100g of acid (g) Amine
C12XSH C12BS
H oleic acid MEA
13.8 2
0.5 21.6 E18-2
82.3
122.4 128.0 E18-5
112.8
167.7 176.6 E18-1
0 163.5 2
43.1 256.1 E18-15
214.2 31
8.5 335.6──────────
──────────────────────────
1 By titration 2 Direct displacement: a) Akzo Ethomeen
18/12 b) Et
home 18/15
c) Ethomeen 18/20
d) Ethomeen 18/2
5 [Example II] Preparation of microemulsion A microemulsion was prepared as follows. The surfactant was weighed and placed into a 16 x 125 mm flat bottomed tube with a Teflon lined lid. A total of 15 ml of diesel fuel and water were added. The tube was shaken and heated to 60-70°C for 30 minutes to 1 hour. Then, the mixture was tumbled in an automatic tumbler for one day and night to two days. Many systems, particularly those using alkylbenzene sulfonates, did not become clear at room temperature even after two days of tumble. Changing the temperature from 70°C to 0°C two or three times will often result in clarity. Clarity improved over time for systems containing MEA soap when stored at room temperature. The system based only on C12XS-E18-n surfactant was very temperature sensitive and the clarity decreased over time. Systems that are initially single-phase and clear often phase separate when stored at room temperature. The cause was hypothesized to be laboratory temperature changes and the high temperature sensitivity of these systems. Due to insufficient storage stability, C12XS-E1
The 8-n surfactant only blend was initially excluded from further studies. However, studies on these surfactants have shown that clear microemulsions can be obtained using 3% by volume water and as little as 1 g/dl (~1%) surfactant. A clear single phase system containing 5% water stabilized by 2g/dl C12XS-E18-n surfactant was also prepared. These C12XS-E18-n
Blends of surfactants and MEA-based surfactants (e.g. C12BS-MEA or C12XS-ME
A) had good stability. It is described below. [Example III] Selection and equilibrium of hydrophilic and lipophilic surfactants Monoethanolammonium dodecylbenzene sulfonate (hereinafter abbreviated as C12BS-MEA) and Marave
A 2 gm/dl mixture with an equal blend of n diesel fuel (oil) and water forms a microemulsion of the lower phase at 20°C. The amount of oil solubilized per gram of surfactant (amount of oil captured) is
This is greater than the most preferred standard for hydrophilic surfactants of 2 ml of oil per gram. Diethoxyoctadecylammonium dodecylbenzenesulfonate (hereinafter C1
2BS-E18-2) and an equal blend of Maraven diesel fuel and water form a microemulsion of the upper phase at 20<0>C. The amount of water solubilized (water uptake) per gram of surfactant is greater than the most preferred standard for lipophilic surfactants of 2 ml of water per gram of surfactant.

[0026]C12BS-MEA/C12BS-E18
The combination -2 represents a hydrophilic-lipophilic surfactant pair, whose combined hydrophilic and lipophilic properties are C12B
It changes by adjusting the weight ratio of S-MEA/C12BS-E18-2. Table 2 shows C12 at different water to Maraven oil ratios and total surfactant concentration.
Figure 2 shows phase data for the BS-MEA/C12BS-E18-2 surfactant pair. The data were obtained as follows. The concentration of surfactant was fixed, for example, at 2 g/dl of oil and water at a water/oil ratio of 5/95. Then,
The hydrophilicity in the surfactant pair is determined by the surfactant C1
The weight fraction of 2BS-MEA was varied from 0.45 to 0.60. After reaching equilibrium, we focused on the type of microemulsion at each weight fraction of C12BS-MEA. The change in microemulsion type showed an approximate phase transition boundary between the upper single-phase and lower single-phase microemulsions. The boundaries of these transitions are shown in Table 2. 1
．． Similar procedures were repeated at surfactant concentrations of 5 and 1.0 g/dl to determine approximate transition boundaries. Data were developed for a series of individual equilibrium tubes containing specified proportions of surfactant at the total surfactant concentrations shown in Table 2 in water and oil at a volume ratio of 5/95. The region of single phase is between the boundaries of the upper and lower phase transitions. The point where these phase boundaries coincide is Mara.
ven indicates the minimum surfactant concentration to solubilize 5% water in diesel fuel. In this case, slightly more than 1 g/dl of surfactant would be required to form a stable emulsion. However, its proximity to the phase transition boundary indicates that it is not a transparent system. Generally, the most transparent systems are found furthest from the transition boundary, ie, in the center of the single phase region. The closer we get to the boundaries of the transition, the more opaque the system located between them becomes. Therefore, the maximum clarity for a given water concentration is
The highest concentration of surfactant is obtained.

Table 2 shows C12BS-MEA/C12BS-E1 when the water/oil capacity ratio is fixed at 4/96.
Similar phase data for the 8-2 surfactant pair are also presented. The single phase region expands, and for 2 g/dl surfactant, C12BS-M in a system with a water/oil volume ratio of 5/95.
While the weight fraction of EA is 0.48 to 0.56, it is 0.47 to 0.59. Again, the most transparent system is found in the center of the single phase region, with the 4/96 system being 5
Since it is farther from the phase transition boundary than the /95 system, the former system is more transparent than the latter system. Water/oil volume ratio is 4/
The 96 system forms single phase microemulsions at surfactant concentrations somewhat below 1 g/dl. This microemulsion is cloudy because it is close to the phase transition boundary.

The data in Table 2 make the conclusion that higher surfactant/water ratios provide clearer microemulsions more convincing. In a system with a water/oil volume ratio of 3/97, the single phase region at a surfactant concentration of 2 g/dl is a C12BS-MEA weight fraction of 0.46 to 0.60. Therefore, microemulsions in the center of this range are far from the transition boundary and have a water/oil volume ratio of 5/95 or 4/9.
It is more transparent than that found in the 6 system. 3/
The 97 system forms single phase microemulsions at surfactant concentrations higher than 0.75 g/dl. 5/9
5 and 4/96 water/oil systems, the minimum surfactant concentration in single-phase microemulsions for all these water/oil ratios corresponds to a water/surfactant ratio of 4/1. I understand that.

The data in Table 2 illustrate important properties in selecting and balancing hydrophilic/lipophilic surfactant blends for given amounts of water and surfactant. Data show that stable microemulsions can be prepared using up to 5% water and less than 1.5% surfactant. As the concentration of surfactant increases, the amount of water solubilized increases proportionately. These surfactants are more efficient than those found in the prior art.

[Table 2] C12BS-MEA/C12B for single phase
S-E18-2 formulation
(g/dl) C12BS-M
Weight fraction of EA 1 W/O volume ratio Surfactant concentration Upper phase TB2 Lower phase TB3
5/95 1.0
0.52 0.5
2 1.
5 0.50
0.54
2.0 0.48
0.56 4/96
1.0 0.53
0.53
1.5 0
．． 50 0.56
2.0
0.47 0.59
3/97 0.75
0.52 0.52
1.0
0.50 0.
54 1
．． 5 0.48
0.57
2.0 0.46
0.60 ────────────
──────────────────────
1) At all indicated surfactant concentrations 2
) Upper phase transition boundary U→S 3) Lower phase transition boundary S→L C12BS-MEA/C1 mentioned above
Although not studied as extensively as the 2BS-E18-2 system, C12XS-MEA/C12XS-E
The system 18-5 also shows similar phase behavior. In this case, C12
XS-MEA is hydrophilic; as its weight fraction increases, a microemulsion of the lower phase is formed. 1.5g
/dl of three types of water at a fixed surfactant concentration of /dl.
The phase data obtained for oil ratios are shown in Table 3 below.

[Table 3] C12XS-MEA/C12X for single phase
S-E18-5 formulation
C12X
S-MEA weight fraction 1 W/O capacity ratio
UTB2
LTB3 5.0/95.0
0.49
0.55 4.5/95.5
0.47 (estim
．． ) 0.57 4.0/96.0
0.44 (estim
．． ) 0.60 ──────────────
────────────────── 1)
At a total surfactant concentration of 1.5 g/dl
2) Upper phase transition boundary: U→S 3)
Lower phase transition boundary: S→L As mentioned above, as the water/oil ratio decreases, the single phase region located between the upper phase transition boundary (UTB) and the lower phase transition boundary (LTB) widens and the transparency decreases. will be improved. The clarity of the microemulsion at the center of the single phase region is C12BS-MEA/C1
Somewhat better than that observed in the 2BS-E18-2 system. Furthermore, the speed at which equilibrium is reached is C12X
S-MEA/C12XS-E18-5 system is faster;
Fewer temperature cycles are required, and the clarity achieved during room temperature storage after temperature cycling is also faster. Example IV: Preparation of Microemulsions from Concentrates The use of concentrates as intermediate formulations was investigated to see if other methods of preparing the final microemulsions would speed up reaching equilibrium. Ta. These concentrates were prepared by removing the oil and, in some cases, some of the water from the final formulation. For example, the following concentrates were prepared.

Concentrate
NB 14483-75A C12XS-MEA
3.0% by weight C12E18-5
12.0CK #905
37 D. O. 25.0 water

50.0 surfactant was dissolved in diesel oil at room temperature and finally mixed with water. The system forms a thin transparent gel at room temperature, which melts into a clear liquid upon gentle warming. 1.2g of this concentrate
When added to 4.1 ml of diesel fuel, the resulting mixture is cloudy but slowly clears over a period of several hours, forming a clear microemulsion. After mixing the concentrate with the diesel fuel several times for a few minutes, the system eventually becomes a clear microemulsion. This shows that the equilibrium rate is composition as well as temperature dependent. It is also shown that it is advantageous to predilute the aforementioned concentrate with diesel oil. With this in mind, Applicants have prepared the following concentrates.

Concentrate
NB 14483-76A C12XS-MEA
10.4% by weight C12XS E18-5
9.6CK #90537
D. O. 40.0 water
4
0.0 surfactant was dissolved in diesel oil at room temperature and finally mixed with water. The mixture was cloudy at first, but after being gently warmed (40°C) and stirred for a few hours, it slowly became clear and finally became a clear amber "solution".
form. When this liquid concentrate is diluted 10 times, 2% by weight of surfactant and 4% by weight are immediately combined with almost no mixing.
A clear microemulsion containing water is formed. This microemulsion ranges from -10°C (lower cloud point) to >7°C.
It is transparent over a temperature range of 0° C. (upper cloud point) and is indefinitely stable at room temperature. It is not known to date whether the turbidity below -10°C is due to phase separation in the microemulsion or to precipitation of wax from the diesel fuel.

The aforementioned concentrate has a water/surfactant volume ratio of 2/1. In an attempt to increase the water/surfactant ratio, the following concentrates were prepared. Concentrate NB 14
483-78BC12XS-MEA
5.78wt% C12XS
E18-5 5.33
CK #90537 D. O. 55.
56 water
33.33 The water/surfactant ratio of this concentrate is 3/1. No attempt was made to optimize the H/L ratio of surfactant to water. Clarity was obtained by adjusting the oil/water ratio in the concentrate. Diluting 1.89 g of this concentrate with 8.2 g of diesel oil immediately gives a clear microemulsion containing 2% surfactant and 6% water. This microemulsion has a high water content and therefore concentrate NB 1
Not as clear as the microemulsion prepared using 4483-76A. Clarity can be improved by optimizing the H/L ratio of the surfactant. This approach ensures that the water/surfactant ratio can be increased even further. Example V: Ammonium Nitrate Diesel Fuel Microemulsion NH4NO3 is added to the microemulsified aqueous phase to determine whether cetane loss due to microemulsified water can be removed by addition of a cetane improver. We conducted an experiment. Table 4 shows the results of our study with addition of up to 10% by weight of NH4NO3 relative to water. Microemulsions contain 10% aqueous phase, so 10% NH4NO3 in water totals 1
%NH4NO3 concentration. Based on previous results with oil-soluble cetane improvers such as octyl nitrate, 0.1% to 1000 ppm NH4
It was considered that NO3 is effective in improving the cetane number.

Table 4 shows the hydrophilicity/lipophilicity (H
/L) shows the phase behavior of microemulsions with changes in ratio and salinity. The H/L ratio depends on the average degree of ethoxylation in the surfactant mixture and is varied by varying the weight ratio of ethoxylated surfactant. Under the column labeled Microemulsion (ME) type, the phase separation characteristic of a given formulation is indicated. The upper phase microemulsion (U) is formed when the H/L ratio is low and the salinity is high as a phase separated system in which the oil-dispersed microemulsion is in equilibrium with excess settled water. The lower phase microemulsion (L) is formed when the H/L ratio is high and the salinity is low as a phase separated system in which the water-dispersed microemulsion is in equilibrium with excess floating oil. Single-phase microemulsions (S) have a relatively narrow range of H
/L ratio and salinity and is a relatively transparent, thermodynamically stable dispersion containing all components. The last column lists Nephelometric Units (NTU), which is a measure of the clarity of single-phase microemulsions. Below 50 NTU, the system is completely transparent. 50 to 100NTU
If so, the system is transparent, but there is a very slight haze. Between 100 and 200 NTU, the haze clearly increases, but the microemulsion remains transparent. 2
When the concentration exceeds 00 NTU, the system becomes translucent but becomes more cloudy. It is considered satisfactory if it is 150 NTU or less.

Table 4 shows that in order to prepare single-phase microemulsions at high salinity, the proportion of more highly ethoxylated surfactants must be increased. Therefore, when increasing NH4NO3 from 5% to 10%, C12XS-E18-10/C12XS-E18-5
Increase the ratio from 1/1 to 2.3/1. This ratio is in the middle of the single-phase region and has the least amount of haze. U→
The system becomes the haziest near the S and S→L phase transition boundaries.

[0037]

[Table 1]

Example VI Hydrogen Peroxide Diesel Fuel Microemulsion Another method of increasing the cetane number of microemulsified fuels is the addition of aqueous hydrogen peroxide. The table below shows how water can be added to 3% H2O2 in a salt-free microemulsion.
We show that direct substitution with 20% yields clear and stable microemulsions without re-equilibration.

Microemulsion surfactant in DF2 with cetane improver, g/dl C12XS-MEA C12XS-E5
Aqueous phase ME type NTU
2.00 2.0
0 Water S
68 2.00
2.00 3% H2O2
All S55 systems contain 10% by volume aqueous phase and 90% by volume DF2. Example VII Oleate Surfactants for Diesel Fuel Microemulsions An advantage of carboxylate surfactants is that they do not add sulfur to diesel fuel microemulsion formulations. Sulfur-containing compounds in diesel fuel are environmentally undesirable because they can form sulfur oxides in diesel exhaust. In some regions, maximum sulfur levels in diesel fuel have been established. For example, in California, 5
It was specified that it should not exceed 0.00 ppm. The examples in Table 5 show that water and aqueous NH4NO in diesel fuel
We show that oleate surfactants are effective in preparing single-phase microemulsions of 3. The aqueous phase to surfactant ratio is 2.5:1, indicating that ethoxylated alkylammonium oleate surfactants are effective microemulsifying agents when properly equilibrated. When using ethoxylated alkylammonium alkylaryl sulfonates, increasing the NH4NO3 concentration requires increasing the degree of ethoxylation to equilibrate the surfactant. This shows the importance of surfactant balance, which is highly dependent on the aqueous phase formulation. Temperature sensitivity may also be minimized by blending two or more surfactants with contrasting temperature dependencies. Ethoxylated alkylammonium oleates become more lipophilic with increasing temperature, while MEA-oleates become more hydrophilic. Blends of these surfactants form temperature insensitive microemulsions.

[0040]

[Table 2]

Claims (7)

[Claims] 1. (a) diesel fuel; (b) about 1.0 to about 30.0% water by weight of said diesel fuel; (c) about 1 to about 1% to about 30.0% by weight of said water; Approximately 3
an alkanol having carbon atoms; (d) an inorganic oxidizing agent of up to about 20.0% by weight of said water;
an additive selected from the group consisting of polar organic oxidants and compounds comprising nitrogen oxides; and (e) a single phase translucent microemulsion of about 0.5 to about 15.0% by weight of said diesel fuel. a surfactant system comprising an equilibrium blend of a hydrophilic surfactant and a lipophilic surfactant in sufficient proportions to form a cetane number and combustion properties of the diesel fuel during combustion in a diesel engine. Improved and smoke, soot emission,
Diesel fuel formulations that reduce dust emissions and NOX emissions. 2. The hydrophilic and lipophilic blend of surfactants has the following formula: or an alkylbenzene group, in which the benzene ring may be further substituted with one or two alkyl groups containing 1 to 3 carbon atoms). Ammonium, alkanol ammonium, or ethoxylated alkyl or alkanol ammonium salt; (b) General formula: R1 is an alkylaryl group, and X is -O-, -S-, -NR3H-, -NR2-,
[-NR2-]+ Cl-, -CO-O-, -CO
-OR4O-, -CO-NH- or -SO2NH -, and Y is -H-, -SO3 -M+ or -(PO3
H)-M+ (where M+ is an ammonium cation including an inorganic or alkyl-substituted ammonium cation); R2 is an alkyl group containing 1 to 20 carbon atoms or an (CH2CH2O) group containing 1 to 30 R3 is H or an alkyl group containing 1 to 3 carbon atoms; R4 is a polyhydroxyl group derived from glycerol, glycol, sorbitol, or various sugars; n is It is an integer from 1 to 30. ) ethoxylated surfactant: and (
c) Alkali metal, ammonium, alkylammonium, alkanol ammonium, or The diesel fuel formulation of claim 1 comprising two or more surfactants selected from the group of one or more ethoxylated alkylammonium salts. 3. At least one of the lipophilic surfactants contains less than 6 C9 to C2 ethylene oxide groups.
3. The formulation according to claim 2, which is an ethoxylated C12 to C18 alkyl ammonium salt of an alkylcarboxylic acid or an alkylarylsulfonic acid of 4. 4. At least one of the hydrophilic surfactants contains 6 or more ethylene oxide groups from C9 to C2.
3. The formulation according to claim 2, which is an ethoxylated C12 to C18 alkyl ammonium salt of an alkylcarboxylic acid or an alkylarylsulfonic acid of 4. 5. Smoke, soot emission, dust emission in the combustion of diesel fuel in a diesel engine;
and NOx emissions, wherein the diesel fuel contains about 1.0 to about 3 of the diesel fuel.
adding 0.0% by weight of water and about 0.5 to about 15.0% by weight of a surfactant system, said surfactant system forming a single phase translucent microemulsion. A method comprising an equilibrium blend of a hydrophilic surfactant and a lipophilic surfactant in proportions sufficient to . 6. The hydrophilic surfactant is an alkali metal of alkylcarboxylic acid and alkylarylsulfonic acid, ammonium, C1 to C3 alkylammonium, C2 to C6 alkanol ammonium containing 1 to 3 hydroxyl groups. , and C12 to C18 alkyl ammonium salts having 6 or more ethoxy groups and alkylphenols having 6 or more ethoxy groups. 7. The lipophilic surfactant is a group consisting of alkylphenols having less than 6 ethoxy groups and C12 to C18 alkylammonium salts having less than 6 ethoxy groups of alkylcarboxylic acids and alkylarylsulfonic acids. 6. The method according to claim 5, wherein the method is selected from: