US20120216447A1

US20120216447A1 - Fuels, methods of making them and additives for use in fuels

Info

Publication number: US20120216447A1
Application number: US13/508,358
Authority: US
Inventors: Alexander Francis Psaila; Patrick Grimes
Original assignee: Alternative Petroleum Technologies SA
Current assignee: Alternative Petroleum Technologies SA
Priority date: 2009-11-06
Filing date: 2010-11-02
Publication date: 2012-08-30
Also published as: GB2475090B; WO2011054817A1; JP2013510205A; ECSP12011952A; KR20120110169A; GB0919452D0; EP2496670A1; GB2475090A

Abstract

A water in oil emulsion having 70 to 99 wt % diesel fuel the diesel fuel having 0 to 50 vol % biodiesel blended fuel, 0.5 to 30 wt % water, 0.01 to 5 wt % alkyl amine ethoxylate at least 25 wt % of the alkyl amine ethoxylate being C₁₀to C₁₄alkyl amine ethoxylate and at least 25 wt % of the alkyl amine ethoxylate being C₁₆to C₁₈alkyl amine ethoxylate and 0.03 to 1 wt % of the product obtainable by reacting a polyisobutylene succinic anhydride of molecular weight 9000 to 2600 with 1 to 2 moles of a tertiary alkanol amine. The emulsion is stable and is useful as a biodiesel blended fuel.

Description

This invention relates to emulsion fuels, methods for making them, additives for use in fuels and the use of additives in fuels.
Diesel fuel is a mixture of various paraffinic, naphthenic and aromatic hydrocarbons with a carbon number of between 10 and 22. Diesel fuel also contains small quantities of organic compounds containing sulphur, nitrogen and oxygen. There are various grades of diesel tailored to suit different applications from on- and off-highway transport engines, open flame boilers, and turbine fuels. Conventional diesel is therefore oleophilic and nonpolar.
Water in conventional diesel emulsion fuels have been recognised as commercial fuels for some years. National standards were developed in France in 2000 and in Italy in 2001. The Coordinating European Council For The Development Of Performance Test For Fuels, Lubricants and Other Fluids (“CEC”) has issued a workshop standard; CWA 15145:2004 for them.
The European Emulsion Fuels Manufacturers Association (“EEFMA”) has published information summarising the results of many studies showing that water in conventional diesel emulsion fuels containing about 13 wt % water have emissions reductions of about 25% in NO_x60% in particulates, 80% in smoke and up to 5% in CO₂.
Biodiesel is also known. Biodiesel is a fatty acid alkyl ester. The fatty acid functionality typically comprises a mixture of C₁₈fatty acids such stearic acid, oleic acid, and linoleic acids. Other fatty acids may also be present. The ester functionality is usually methyl on cost grounds but other esters such as ethyl, iso-propyl and butyl have been used. The fatty acid alkyl ester may be used as fuel alone or blended with conventional diesel to give fuels such as B20 and B50 which contain 20 and 50 vol % biofuel respectively. Fatty acid methyl ester is sometimes referred to as FAME. Fatty acid ethyl ester is sometimes referred to as FAEE.
The fatty acid ester is polar with a hydrophilic —COOR head and an oleophilic alkyl tails. Accordingly the fatty acid ester will have a significant effect on the oil/water interface.
Surfactants such as fatty amine ethoxylates (such as those derived from coco fatty acids) and polyisobutylene succinate which give good emulsion stability in water in conventional diesel emulsions do not perform as well in fuels containing biodiesel.
It has been unexpectedly found that a mixture of fatty acid amine ethoxylates together with a polyisobutylene succinic anhydride emulsifier obtainable by reacting a polyisobutylene succinic anhydride (“PIBSA”) containing at least 65 mol %, more preferably at least 70 mol % yet more preferably at least 80 mol % still more preferably at least 85 mol % vinylidene content with a tertiary alkanolamine can stabilise emulsions containing biodiesel. The PIBSA is sometimes known as a highly reactive polyisobutylene or “HR-PIB” from Texas Petrochemicals LP. The preparation of such polymers is known from U.S. Pat. No. 4,152,499 and U.S. Pat. No. 7,037,999. They are commercially available for example as Glissopal® from BASF TPC Isobutenes from Texas Petrochemicals and ULtravis®.
According to the invention there is provided a water in oil emulsion comprising:

- a) 70 to 99 wt % diesel fuel said diesel fuel comprising 0 to 50 vol % biodiesel;
- b) 0.5 to 30 wt % water;
- c) 0.01 to 5 wt % alkyl amine ethoxylate at least 25 wt % of the alkyl amine ethoxylate being C₁₀to C₁₄alkyl amine ethoxylate and at least 25 wt % of the alkyl amine ethoxylate being C₁₆to C₁₈alkyl amine ethoxylate; and
- d) 0.03 to 1 wt % of the product obtainable by reacting a polyisobutylene succinic anhydride of molecular weight 900 to 2600 with 1 to 2 moles of a tertiary alkanolamine per mole of polyisobutylene succinic anhydride to form a salt and/or ester.

The diesel fuel can comprise 5 to 50 vol % biodiesel.
The alkyl amine ethoxylate can comprises a mixture of polyoxyethylene tallow amine and polyoxyethylene coco amine.
The tertiary alkanolamine can be diethylethanolamine.
The emulsion can further comprise 0.01 to 0.1 wt % ammonium nitrate.
The emulsion can further comprise a cetane improver such as 2-ethylhexylnitrate.
The emulsion can further comprise ethylene glycol for example such that the ratio of ethylene glycol to water is in the range 1:3 to 1:13.
The invention further provides the use of alkyl amine ethoxylate comprising at least 25 wt % C₁₀to C₁₄alkyl amine ethoxylate and at least 25 wt % C₁₆to C₁₈alkyl amine ethoxylate, and the product obtainable by reacting a polyisobutylene succinic anhydride of molecular weight 900 to 2600 with 1 to 2 moles of a tertiary alkanolamine per mole of polyisobutylene succinic anhydride in stabilizing water in oil emulsions comprising diesel fuel.
The invention still further provides a composition comprising 1 to 500 parts by weight alkyl amine ethoxylate at least 25 wt % of the alkyl amine ethoxylate being C₁₀to C₁₄alkyl amine ethoxylate and at least 25 wt % of the alkyl amine ethoxylate being C₁₆to C₁₈alkyl amine ethoxylate; and 3 to 100 parts by weight of the product obtainable by reacting a polyisobutylene succinic anhydride adduct of molecular weight 900 to 2600 with 1 to 2 moles of a tertiary alkanolamine per mole of polyisobutylene succinic anhydride.
In accordance with the invention the above composition can be used to stabilise a water in oil emulsion comprising 70 to 99 parts by weight diesel fuel and 5 to 30 parts by weight water.
The invention yet further provides a method of making an emulsion comprising blending

- a) 70 to 99 wt % diesel fuel said diesel fuel comprising 0 to 50 vol % biodiesel;
- b) 0.5 to 30 wt % water;
- c) 0.01 to 5 wt % alkyl amine ethoxylate at least 25 wt % of the alkyl amine ethoxylate being C₁₀to C₁₄alkyl amine ethoxylate and at least 25 wt % of the alkyl amine ethoxylate being C₁₆to C₁₈alkyl amine ethoxylate; and
- d) 0.03 to 1 wt % of the product obtainable by reacting a polyisobutylene succinic anhydride of molecular weight 900 to 2600 with 1 to 2 moles of a tertiary alkanolamine per mole of polyisobutylene succinic anhydride.

The fuel base generally contains 5 to 50 vol % for example 5 to 11 vol % of biodiesel such as fatty acid methyl ester. Typically the biodiesel conforms to EN14214 and/or ASTM D6751. The biodiesel and diesel blend may conform to EN590.
The fuel base may comprise 70 to 99 wt %, such as 80 to 95 wt % for example 85 to 90% of the fuel.
Water, preferably deionised water, comprises 0.5 to 30 wt %, such as 5 to 25 wt % for example 12 to 15 wt % of the fuel.
The fuel further comprises 0.01 to 5 wt % for example 0.03 to 3 wt % such as 0.1 to 2 wt % alkyl amine ethoxylate surfactant. Preferably the fuel comprises 0.03 to 1% alkyl amine ethoxylate surfactant. At least 25 wt % for example at least 35 wt % such as at least 40 wt % of the alkyl amine ethoxylate surfactant is C₁₀to C₁₄alkyl amine ethoxylate surfactant. At least 25 wt % for example at least 35 wt % such as at least 40 wt % of the alkyl amine ethoxylate surfactant is C₁₆to C₁₈alkyl amine ethoxylate surfactant. The amine can be a monoamine or a diamine or a mixture thereof. Typically each mole of functionality amine is reacted with 3 to 8 preferably 4 to 6 moles of ethylene oxide.
By at least 25 wt % C₁₀to C₁₄alkyl amine ethoxylate surfactant it is meant that at least 25% of the alkyl amine ethoxylate has a hydrocarbon chain containing at C₁₀to C₁₄carbon atoms. Mixtures of C₁₀to C₁₄hydrocarbon chains to make up the requisite amount fall within the definition.
By at least 25 wt % C₁₆to C₁₈alkyl amine ethoxylate surfactant it is meant that at least 25% of the alkyl amine ethoxylate has a hydrocarbon chain containing at C₁₆to C₁₈carbon atoms. Mixtures of C₁₆to C₁₈hydrocarbon chains to make up the requisite amount fall within the definition. The hydrocarbon chains may be saturated or unsaturated or mixtures thereof but the term alkyl is used in respect of all.
The alkyl amine ethoxylate will generally be derived from plant or animal sources. Few, if any, commercially available plant or animal sources of fatty acids have the desired chain length profile and mixtures of them will therefore generally be used. In general the alkyl chain will not be subjected to hydrogenation but it may be hydrogenated.
Coconut oil typically contains a large proportion of esters of capric, lauric and myristic acid. Palm kernel oil typically contains large amounts of esters of lauric and myristic acid. These oils either alone or in mixture can comprise a source of fatty acid for the C₁₀to C₁₄alkyl amine ethoxylate surfactant. An example of a C₁₀to C₁₄alkyl amine ethoxylate containing surfactant is Ethomeen® C/15. This is a monoamine ethoxylated with 5 moles of ethylene oxide per mole of amine functionality.
Tallow, canola, olive, palm, soybean and sunflower oils are each good sources of fatty acids in the C₁₆to C₁₈range. Examples of C₁₆to C₁₈alkyl amine ethoxylate containing surfactants are Ethomeen® T/15 and SV/15 which are respectively tallow and soybean based. Each are monoamines ethoxylated with 5 moles of ethylene oxide. Another example this time a tallow diamine with three moles of ethylene oxide is Ethoduomeen®. These products are produced by Akzo Nobel.
Other suitable alkyl amine ethoxylates such as those selected from Huntsman's Empilan® range can be used.
The fuel yet further comprises a PIBSA derived emulsifier. The PIBSA from which the emulsifier is made contains at least 70 mol % vinylidene and has a number average molecular weight in the range 900 to 2 600 such as 1 400 to 2 000 especially about 1 300. In some embodiments of the invention the PIBSA of molecular weight 900 to 2 600 is obtained by blending two or more PIBSAs. For example PIBSA of molecular weight 1 300 can be achieved by blending a mixture of 65 parts by weight of material having molecular weight of 950 with 35 parts by weight of material having molecular weight of 2 350 The PIBSA is further reacted with between one and two molar equivalents of a tertiary alkanolamine or mixture of tertiary alkanolamines. Tertiary alkanolamines include dimethylethanolamine and diethylethanolamine. The PIBSA is mainly in the form of monosuccinate. Less than 30 mol % preferably less than 20 mol % of the PIBSA is in the form of the disuccinate. The emulsifier is present in an amount ranging from 0.03 to 1 wt % for example 0.05 to 0.5 wt % such as 0.1 to 0.3 wt %.
Optionally other components may be present.
For example the aqueous phase may contain a water soluble additive. An example is ammonium nitrate which acts as an emulsion stabiliser. Ammonium nitrate where present may be used in the range of 0.01 to 0.1 wt % preferably 0.04 to 0.08 wt %.
Cetane improvers may be used. Examples of cetane improvers are alkyl nitrates such as 2-ethylhexyl nitrate and alkyl peroxides such as di tert-butyl peroxide. If present preferably 2-ethylhexyl nitrate is used. Typically 2 000 to 8 000 ppm of cetane improver is used.
Antifreeze chemicals can also be used. Typically they are used to suppress the freezing point of water to −15° C. or less. Examples of antifreezes are ethylene glycol and propylene glycol. Typically where present and depending on the ambient temperatures to which the fuel will be exposed the mass ratio of glycol to water is in the range 1:3 to 1:13.
The additives can be mixed together for example by dissolving in a hydrocarbon such as an aliphatic or aromatic hydrocarbon or mixture thereof solvent. The water, fuel base and additive mixture can be mixed and emulsified in conventional way.
The invention will be illustrated by reference to the accompanying examples. Unless otherwise stated percentages are weight percentages.
The following techniques were used to characterize the emulsions:
(1) Optical microscopic examination of the emulsion using 400× magnification with a calibrated graticule for sizing of individual particles is routinely carried out to evaluate subjectively the size and population of the larger droplets. Phase contrast and polarised light microscopy can assist in determining the presence of multiple emulsion and similar phenomena. Capturing images is also a useful facility. Microscopy has the advantage of enabling the viewing of the undiluted emulsion. However it views only a drop and care needs to be exercised to ensure that the drop is representative of the bulk. Skilled microscopy can differential and rank various emulsions in order of size distribution accurately. Microscopy is not able to clearly resolve particles below 0.5 μm. A comparative system for ranking emulsions into categories can be useful.
(2) Centrifuge. The French and Italian national standards as well as CEN WS15147:2004 define a method (MU 1548) where a 50 cm³sample of the emulsion is placed in a graduated tube and centrifuged for 5 minutes at 4200 rcf (relative centrifugal force). The passing criteria are (a) no free water; and (b) a maximum white sediment band of 7% and 9% (vol.) for the 8% and 15% (mass) maximum water emulsions respectively. This test was originally conceived as a predictor of future emulsion stability (an accelerated aging test). In fact there is no simple test for predicting emulsion stability. Slow aging processes of the surfactant molecules (hydrolysis, oxidation, partitioning and redistribution of molecules, etc.) will adversely affect the ability of the surfactants to prevent the droplets from flocculating, coalescing and sedimenting. The centrifuge test can accelerate the sedimentation process but it cannot be used to predict the aging of the surfactants. The centrifuge test has been modified in order to characterise in detail the robustness of the emulsion by measuring the sediment formed after 5, 15, 25 and 35 minutes of centrifuge.
(3) A storage stability test which involves placing a sample (usually 100 cm³) in a tall, clear glass, flat bottomed seal tube and standing in the dark for up to 3 months, without agitation and at ambient temperature (˜20° C.). Periodically (typically after 1, 3, 7 days, 2, 3, 4 weeks, 2 and 3 months) the tubes are examined carefully. Observations are made for (a) signs of ‘free’ water; droplets or layers foimed at the bottom of the tubes; (b) the volume of ‘white’ sediment band formed at the bottom of the tube which is measured with a ruler and expressed as a % of the total height of the fluid in the tube; (c) the volume of ‘clear oil’ formed at the top of the sample. This is also expressed as a % volume.
(4) Particle Size Analysis by Laser Diffraction. A Coulter™ LS 13 320 was used to measures particle size distributions by measuring the pattern of light scattered by the particles in the sample. It uses a 5 mW laser diode with a wavelength of 750 nm (or 780 nm) as the main illumination source with a secondary tungsten-halogen light source for the Polarization Intensity Differential Scattering (PIDS) system. The light from the tungsten-halogen lamp is projected through a set of filters which transmit three wavelengths (450 nm, 600 nm, and 900 nm) through two orthogonally oriented polarizers at each wavelength. The PIDS assembly provides the primary size information for particles in the 0.04 μm to 0.4 μm range. It also enhances the resolution of the particle size distributions up to 0.8 μm. The combined PIDS and laser assembly enables size distribution from 0.04 microns to 2000 microns to be observed.
By skilful application of these methods an excellent description of the stability of emulsions can be obtained which enables the ranking of changes in surfactants and fuel compositions.
Laboratory emulsions were prepared on a 500 cm³scale. The hydrocarbon fuel (either diesel or a biodiesel blended fuel) was measured in a 1 litre tall form beaker (422.5 g). The additive surfactant was added to the diesel (12.5 g). Invariably the additive readily dissolved in the diesel with gentle stirring using a glass rod. The water to be emulsified was measured accurately in a separate clean beaker (65 g). A Silverson™ Model L4RTA with a 3.1 cm rotor stator mixer was lowered to a level just over mid way down the hydrocarbon phase. The mixer was started at 9200 rpm, corresponding to a tip speed of 15 m/s. The stop watch was started as soon as the water addition was initiated. The water was added over 10 seconds and mixing continued for 5 minutes.
The emulsion was allowed to cool for two hours before centrifuge and particle size analyses were carried out. Changes in particle size were monitored for up to 3 months. Storage stability samples were set aside and observations of sediment, free water and clear oily layer were carried out over a 3 month period.
Surfactant formulations BA1 to BA4 were made by mixing together the components set forth in Table 1. Amounts are given in wt %

TABLE 1

BA1	BA2	BA3	BA4

Isopar M	15.5	15.5	15.5	15.5
Ethoduomeen T/13	25
Ethomeen SV/15		25
Ethomeen C/15			25
Ethomeen T/15				25
PIBSAa	42	42	42	42
2-ethylhexylnitrate	12	12	12	12
52% aq NH₄NO₃	5	5	5	5
DEEA	0.5	0.5	0.5	0.5

Isopar® M is a isoparaffinic hydrocarbon available from ExxonMobil.
Ethoduomeen® and Ethomeen® are amine ethoxylates. They are available from Akzo Nobel. As hereinbefore noted the C/15 contains a significant proportion of C₁₀to C₁₄alkyl units and the T/13, SV/15 and T/15 contain significant proportions of C₁₆to C₁₈alkyl units.
PIBSAa is a 1:2 mole ratio salt of a high vinylidene PIBSA of molecular weight 1000 with diethylethanolamine “DEEA”.
Emulsions were prepared with the four additives BA1, 2, 3, and 4. In all cases the water content of the emulsions was 13 wt %. The additive treat rate was 2 wt % and 2.5 wt %. The base fuel was US #2 diesel a conventional fuel obtained from a commercial outlet.
The results for 2% additive are shown in Table 2

TABLE 2

	Particle size (μm)
Centrifuge (%)	Mean
5 min (4200rcf)	Measured 7 days	D90	Storage Stability

BA1	0.8	0.77	1.70	sediment (2 days)
BA2	0.8	0.49	0.87	sediment (2 days)
BA3	0.4	0.51	1.09	sediment (14 days)
BA4	0.4	0.48	0.78	no sediment

The results for 2.5% additive are shown in Table 3

TABLE 3

	Particle size (μm)
Centrifuge (%)	Mean
5 min (4200 rcf)	Measured 7 days	D90	Storage Stability

BA1	0.8	0.66	1.50	sediment (2 days)
BA2	0.8	0.47	0.82	sediment (7 days)
BA3	0.2	0.57	1.34	sediment (21 days)
BA4	0.4	0.55	1.06	no sediment

The results show that good emulsions were obtained in all cases with larger amounts of additive giving better results. Additives BA3 and BA4 gave better results than BA1 and BA2.
Since BA3 gave good results attempts were made to optimize the proportion of the surfactants in such as system.
The following additive compositions shown in Table 4 were made up

TABLE 4

BA3	BA5	BA6	BA7	BA8

Isopar M	15.5	12.5	19.2	12.5	13
Ethomeen C/15	25	20	30	35	35
PiBSAa	42	50	33.3	35	35
2-	12	12	12	12	12
ethylhexylynitrate
52% aq. NH₄NO₃	5	5	5	5	5
DEEA	0.5	0.5	0.5	0.5	0

Once again emulsions were made with 13 wt % water and US #2 diesel with 2 wt % and 2.5 wt % additive.
The results are shown in Table 5

TABLE 5

Centrifuge (%)	Particle size (μm)
5 min	Mean
(4200 rcf)	Measured 7 days	D90	Storage Stability

BA3 2%	0.4	0.51	1.09	sediment
				(14 days)
BA5 2%	0.8	0.58	1.44	water tr. (7 days)
BA6 2%	0.4	0.52	1.24	no sediment
BA8 2%	0.2	0.47	1.07	no sediment
BA7 2.5%	0.2	0.37	0.54	no sediment
BA8 2.5%	0.2	0.38	0.58	no sediment

The results show that the best initial emulsion and best emulsion on aging is obtained when equal mass of the two key surfactants are present in the surfactant additive formulation; that is to say using BA7 and BA8.
Additive BA8 was then optimized for concentration of surfactant and amount of ammonium nitrate. The additive compositions shown in Table 6 were prepared

TABLE 6

BA8	BA8A	BA8B	BA8C	BA8D

Isopar M	13	23	11	15	18
Ethomeen C/15	35	30	35	35	35
PIBSAa	35	30	35	35	35
2-ethylhexylynitrate	12	12	12	12	12
52% aq. NH₄NO₃	5	5	7	3	0

The stability of 13 wt % water emulsions with US #2 diesel and 2% additive was again tested. The results obtained are shown in Table 7

TABLE 7

	Particle size (μm)
Centrifuge (%)	Mean
5 min (4200 rcf)	Measured 7 day	D90	Storage Stability

BA8	0.2	0.47	1.07	No sediment
BA8A	0.4	0.63	1.55	No sediment
BA8B	0.2	0.45	1.10	No sediment
BA8C	0.2	0.52	1.52	No sediment
BA8D	1.6	1.2	2.4	Free water

It is apparent from these results that ammonium nitrate has a significant effect on emulsion stability and quality.
The optimized additive BA8 was then tested with biodiesel blended fuel B20 (ie diesel containing 20% biodiesel) and with US#2 hydrocarbon diesel. Once again 13 wt % water and 2 wt % additive were used. The results are shown in Table 8.

TABLE 8

	Particle size (μm)
Centrifuge (%)	Mean
5 min (4200 rcf)	Measured 7 days	D90	Storage Stability

US#2	0.2	0.47	1.47	No sediment
B20	Free water	Free water		Free water

The results shown in Table 8 show a dramatic difference between biodiesel blended fuel and conventional diesel. With conventional diesel an excellent emulsion with no sediment forming even after 3 months storage is obtained. When this additive is used with diesel containing 20% biodiesel the emulsion is unstable and worse than that obtained with conventional diesel and any of the other additives tried.
Investigation was then made of the effect of introducing a C₁₆to C₁₈alkyl amine ethoxylate to the additive BA8. The additives in Table 9 were prepared.

TABLE 9

BA8	BA9	BA10	BA11	BA12

Isopar M	13	13	13	13	13
Ethomeen C/15	35	0	15	20	10
Ethomeen T/15	0	35	20	15	25
PIBSAa	35	35	35	35	35
2-	12	12	12	12	12
ethylhexylynitrate
52% aq. NH₄NO₃	5	5	5	5	5

Once again 13 wt % water emulsions using 2.5 wt % additive were tested. The results are shown in Table 10.

TABLE 10

		Particle size
		(μm) Mean		Storage Stability
	Centrifuge (%)	Measured		(after 7 days)
Fuel	5 min (4200 rcf)	7 day	D90	s

BA8	US#2	0.4	0.51	1.61	No sediment
BA9	US#2	0.2	0.39	1.21	No sediment
BA10	US#2	0.2	0.46	1.34	No sediment
BA11	US#2	0.2	0.40	0.58	No sediment
BA12	US#2	0.2	0.32	0.46	No sediment
BA8	B20	0.2	Free water
			after 3 days
BA9	B20	0.8	0.66	1.61	Water (3 days)
BA10	B20	0.4	Free water
			after 3 days
BA11	B20	0.4	Free water
			after 3 days
BA12	B20	0.4	0.34	0.53	Water (14 days)

Again the differences between conventional diesel and biodiesel blended fuel are dramatic. All the additives gave excellent emulsions with conventional diesel but soon fell apart with biodiesel blended fuel.
Experiments were then made to see the effect of varying the PIBSA emulsifier. The additives shown in Table 11 were prepared.

TABLE 11

BA13	BA14	BA15	BA16	BA17	BA18

Isopar M	15.5	10.5	10.5	28	18	8
Ethomeen C/15	25	25	5	25	25	25
Ethomeen T/15	0	5	25	5	5	5
PIBSAa	30	30	30	25	30	35
PIBSAb	12	12	12	0	5	10
2-ethylhexyl nitrate	12	12	12	12	12	12
52% aq. NH₄NO₃	5	5	5	5	5	5
DEEA	0.5	0.5	0.5	0	0	0

PIBSAb is a similar product to PIBSAa. The PIBSAb product is based on the 2350 molecular weight high vinylidene PIB, which is reacted with maleic anhydride to give the mono succinic anhydride which is reacted with water and DEEA to form a mixture of salt, ester and succinimide.
Once again 13 wt % water emulsions with 2.5 wt % additive were prepared and tested. The results are shown in Table 12.

TABLE 12

		Particle size
		(μm) Mean
	Centrifuge (%)	Measured 7		Storage Stability
	5 min (4200 rcf)	days	D90	(after 7 days)

BA13	US#2	0.4	0.40	1.00	no sediment
BA14	US#2	0.2	0.49	1.39
BA15	US#2	0.4	0.53	1.49
BA16	US#2	0.4	Free water
			after 3 days
BA17	US#2	0.2	Free water
			after 3 days
BA18	US#2	0.4	0.58	1.68	no sediment
BA13	B20	0.4	0.41	1.11	no sediment
BA14	B20	0.4	0.36	1.06	no sediment
BA15	B20	0.8	0.61	1.52	sediment (2 days)
BA16	B20	—	Free water
			in few hours
BA17	B20	0.4	Free water
			after 4 days
BA18	B20	0.4	0.40	1.30	no sediment

Promising emulsions were obtained with BA13, 14 and 18. The low levels of PIBSAb (or none) give poor emulsions. This confirms that better emulsions are obtained in the presence of PIBSAb.
The surfactant ratio was further optimized by trials with differing surfactant ratios. The additives shown in Table 13.

TABLE 13

BA23	BA24	BA25	BA26

Isopar M	17	17	17	17
Ethomeen C/15	21	19	17	15
Ethomeen T/15	9	11	13	15
PIBSAa	22.5	22.5	22.5	22.5
PIBSAb	12.5	12.5	12.5	12.5
2-ethylhexylynitrate	12	12	12	12
52% aq. NH₄NO₃	6	6	6	6

As in previous tests the stability of 13 wt % emulsions and 2.5 wt additive were determined. The results are shown in Table 14.

TABLE 14

	Centrifuge (%)	Particle size (μm)		Storage
	5 min	Mean		Stability
	(4200 rcf)	Measured 7 days	D90	(after 7 days)

BA23	US#2	0.4	0.44	1.41	no sediment
BA24	US#2	0.4	0.37	1.59	trace water
BA25	US#2	0.4	0.37	0.95	no sediment
BA26	US#2	0.4	0.41	1.24	no sediment
BA23	B20	0.4	0.49	1.42	no sediment
BA24	B20	0.4	0.37	1.59	water (14 days)
BA25	B20	0.8	0.39	1.23	sediment
					(21 days)
BA26	B20	0.8	0.34	1.16	no sediment

The best emulsion was obtained with BA26. The initial emulsion was good and readily formed and no water or significant sediment observed over a 1 month period. All the additives tested in this trial however gave satisfactory results with biodiesel blended fuels.
The effect of B26 in stabilizing a range of diesels was then determined. The results are shown in Table 15.

TABLE 15

	Centrifuge (%)	Particle size (μm)	Storage
BA26	(4200 rcf)	Mean	Stability

Fuel	% mass	5	35 min	Measured 7 days	D90	(after 7 days)

B6	1.7	1.6	8.4	0.69	1.66	no sediment
B6	2.5	0.8	4.8	0.46	1.50	no sediment
B20	2.5	0.8	4.8	0.33	1.14	no sediment
US#2	2.5	0.4	3.6	0.47	1.43	no sediment

It is clear that the additive stabilized a range of conventional diesel and biodiesel blend emulsions.
The effect of BA26 in stabilizing emulsions with different water and ethylene glycol content was then tested as shown in Table 16.

	TABLE 16

		Particle
	Centrifuge (%)	size (μm)

(4200 rcf)

Mean

D90

Storage Stab

Glycol	BA26	Water	5	35 min	Measured after 56 days

0.6	1.7	5.4	0.2	1.6	0.29	0.53	no sediment
1.0	2.0	9.0	0.4	3.6	0.41	0.71	no sediment

It will be apparent that the formed emulsion is stable in the presence of ethylene glycol and with different water content.
Table 17 sets forth further compositions of the invention:

TABLE 17

A	B	C	D

EES6535X	35	39.77	35	35
Solvesso 150ND	17	19.32	9	29
Ethomeen C15	15	17.05	15	15
Ethomeen T15	15	17.05	15	15
2-Ethylbexyl nitrate	12	0	20	0
52% aq Ammonium	6	6.81	6	6
Nitrate

All percentages are by mass.

EES6535SX is obtained by reacting a 65:35 mass ratio mixture of polyisobutylsuccinate of molecular weight (M_w) 950 and 2 350 with maleic anhydride and then with alkanolamine. The obtained additives produced stable biodiesel blended fuel emulsions.
In addition to stabilizing water in diesel and biodiesel emulsions the invention can be used to stabilize emulsions of other distillate containing fuels such as marine gas oil (“MGO”) and Marine Fuel Oil (“MFO”) which is also known as Residual Fuel Oil (“RFO”) and mixtures thereof such as Intermediate Fuel Oil (“IFO”) which is also known as Marine Diesel Fuel (“MDF”) as can be seen from the following experiments using IFO380 which is to say IFO having a kinematic viscosity at 50° C. of 380 mm²/s using a emulsifier BA27 having the following composition:


Solvesso 150ND (ex ExxonMobil)	29	wt %
Ethomeen C/15	15	wt %
Ethomeen T/15	15	wt %
PIBSAa	22.5	wt %
PIBSAb	12.5	wt %
52% aq NH₄NO₃	6

Emulsions of the IFO380 were prepared by preheating the ingredients to 60° C. and mixing for three minutes at 2400 rpm using an UltraTurrax T25. All proportions are by weight.


12A	12B	12C	12D	12E

IFO380	85	84.7	84.5	84	83.5
BA27	0	0.3	0.5	1	1.5
Water	15	15	15	15	15
Total	100	100	100	100	100

The emulsions were stored in an oven at 70° C. Samples were taken from the top, middle and bottom daily and the water content (wt %) determined using the Karl Fischer method. Several samples of each example were prepared since determination destroyed the samples. The results obtained were as follows:


Sample	Day	Top	Middle	Bottom

12A	1	10.56	14.54	16.86
12A	2	6.05		18.28
12A	3	0.58		26.79
12B	1	14.24	14.34	13.70
12B	2	14.78		13.68
12B	3	14.28		13.94
12C	1	14.15	14.26	13.94
12D	1	14.31	14.34	13.99
12E	1	14.24	14.16	13.70

It will be seen that without the emulsifier the emulsion is unstable and heterogeneous but with the emulsifier it is stable and homogenous.

Claims

1. A water in oil emulsion comprising:

a) 70 to 99 wt % diesel fuel said diesel fuel comprising 0 to 50 vol % biodiesel blended fuel;

b) 0.5 to 30 wt % water;

c) 0.01 to 5 wt % alkyl amine ethoxylate at least 25 wt % of the alkyl amine ethoxylate being C10 to C14 alkyl amine ethoxylate and at least 25 wt % of the alkyl amine ethoxylate being Cj6 to Ci8 alkyl amine ethoxylate; and

d) 0.03 to 1 wt % of the product obtainable by reacting a polyisobutylene succinic anhydride of molecular weight 900 to 2600 with 1 to 2 moles of a tertiary alkanolamine per mole of polyisobutylene succinic anhydride.

2. The emulsion as claimed in claim 1 wherein said diesel fuel comprises 5 to 50 vol % biodiesel blended fuel.

3. The emulsion as claimed in claim 1 wherein the alkyl amine ethoxylate comprises a mixture of polyoxyethylene tallow amine and polyoxyethylene coco amine.

4. The emulsion as claimed in claim 1 wherein the tertiary alkanolamine is di ethyl ethanol amine.

5. The emulsion as claimed in claim 1 further comprising

0.01 to 0.1 wt % ammonium nitrate.

6. The emulsion as claimed in claim 1 further comprising a cetane improver.

7. The emulsion as claimed in claim 6 wherein the cetane improver comprises 2-ethylhexylnitrate.

8. The emulsion as claimed in claim 1 further comprising ethylene glycol.

9. The emulsion as claimed in claim 8 wherein the ratio of ethylene glycol to water is in the range 1:3 to 1:13.

10. The use of alkyl amine ethoxylate comprising at least 25 wt % Cio to C14 alkyl amine ethoxylate and at least 25 wt % Ci6 to Cis alkyl amine ethoxylate, and the product obtainable by reacting a polyisobutylene succinic anhydride of molecular weight 900 to 2600 reacted with 1 to 2 moles of a tertiary alkanolamine per mole of polyisobutylene succinic anhydride in stabilizing water in oil emulsions comprising diesel fuel.

11. A composition comprising 1 to 500 parts by weight alkyl amine ethoxylate at least 25 wt % of the alkyl amine ethoxylate being do to Cj4 alkyl amine ethoxylate and at least 25 wt % of the alkyl amine ethoxylate being Ci6 to Cis alkyl amine ethoxylate; and 3 to 100 parts by weight of the product obtainable by reacting a polyisobutylene succinic anhydride of molecular weight 900 to 2600 with 1 to 2 moles of a tertiary alkanolamine per mole of polyisobutylene succinic anhydride.

12. The use of the composition as claimed in claim 11 in stabilizing a water in oil emulsion comprising 70 to 99 parts by weight diesel fuel and 0.5 to 30 parts by weight water.

13. A method of making an emulsion comprising blending

a) 70 to 99 wt % diesel fuel said diesel fuel comprising 0 to 50 vol % biodiesel fuel;

b) 0.5 to 30 wt % water;

c) 0.01 to 5 wt % alkyl amine ethoxylate at least 25 wt % of the alkyl amine ethoxylate being do to Cj4 alkyl amine ethoxylate and at least 25 wt % of the alkyl amine ethoxylate being Ci6 to Cis alkyl amine ethoxylate; and