DE69310716T2 - ADDITIVES AND FUEL COMPOSITIONS - Google Patents

Abstract

An additive composition for improving the cold flow properties of crude oils or fuel oils such as middle distillate fuel oils comprises an addition product or condensate cold flow improver additive in combination with a demulsifier.

Description

This invention relates to the use of additives for improving the cold flow properties of crude oil or fuel oil, e.g. distillate petroleum fuel such as middle distillate fuel oil boiling in the range of 110ºC to 500ºC.

When oils and fuel oils are exposed to low ambient temperatures, paraffin can precipitate from the fuel and affect the flow properties of the oil. For example, middle distillate fuels contain paraffin which precipitates at low temperatures to form large paraffin-like crystals which tend to clog the small pore openings of fuel filters. This problem is particularly acute when the fuel is a diesel fuel because the nominal openings in the fuel filter of diesel engines typically have diameters between about 5 and 50 µm. Additives to overcome the above problem are known in the art and are called flow improvers.

Such additives can act as wax crystal modifiers when mixed with waxy mineral oil, by modifying the shape and size of crystals of the wax therein and reducing the adhesive forces between the crystals and between the wax and the oil, so that the oil remains liquid at a lower temperature than in the absence of the additive.

Many additives for improving the cold flow properties of oils have been described in the art, for example in the form of oil-soluble addition products or condensates which may be polymeric or monomeric and are described for example in US-A-3 048 479; UK-A-1 263 152; US-A-3 961 916 and EP-A-0 261 957. Some of the above additives have been and are used commercially as cold flow improvers. However, there is a need for improved performance, particularly over a range of oils.

In US-A-3,850,587, fuel compositions are described comprising a middle distillate fuel and a flow improver composition comprising a hydrocarbon succinic acid or an amine salt thereof, an ethylene/vinyl acetate polymer and optionally an aromatic monocarboxylic acid. Other additives are described as optionally present, one type being a demulsifier. However, the demulsifiers are not described as having flow improver properties.

It has surprisingly been found according to the invention that demulsifiers can improve the cold flow properties of oils and can also act synergistically in providing such properties when used in combination with addition products or condensates which themselves have cold flow improving properties. In addition, the proportions of the demulsifier used can be surprisingly small.

A first aspect of the invention consists in an additive composition which

(i) one or more non-metallic flow-enhancing oil-soluble addition products or condensates capable of improving, either jointly or individually, one or more cold flow properties of a crude oil or fuel oil, and

(ii) a non-metallic, oil-soluble demulsifier for crude oil or fuel oil-water emulsions, the demulsifier having a hydrophobic part and a hydrophilic part and being selected from the following groups 1 and 2, wherein group 1 is a condensate comprising as the hydrophobic part a part derived from a precursor having one or more groups capable of undergoing a condensation reaction to form oxyalkylated groups and coupled to one or more oxyalkylated groups that make up the hydrophilic part, and group 2 is a compound having a sulfonate or sulfonic acid group as the hydrophilic part, which is bonded to the hydrophobic part,

with the proviso that component (i) is not a combination of a substituted succinic acid derivative and an ethylene/vinyl acetate copolymer.

The composition may be in admixture with a major proportion of a crude oil or a fuel oil, with the composition constituting a minor proportion. Further, the composition may be dispersed in a liquid medium compatible with a crude oil or a fuel oil to form a concentrate.

A second aspect of the invention consists in the use of an additive composition according to the first aspect of the invention for improving the cold flow properties of a crude oil or a fuel oil.

The examples given below show that a demulsifier used in combination with the addition products and/or the condensates leads to unexpected improvements in the cold flow properties of oils.

The features of the invention are described in more detail below.

DEMUSLIFIER

In this specification, a demulsifier is a material capable of causing a breaking of an oil-water emulsion to form discrete, separable oil and water phases, the oil being a crude oil or a fuel oil according to the invention, for example in a concentration of 0.1 to 2 000 ppm based on the weight of the fuel. It is an equilibrium between the hydrophilic and hydrophobic properties is required. Therefore, it must be sufficiently hydrophobic to dissolve in the oil of an oil/water emulsion to break the emulsion and it must be sufficiently hydrophilic to favor the aqueous phase which separates from the oil phase after emulsion breaking.

The demulsifier can be a surfactant that changes the surface or interfacial tension of the droplets in the disperse phase of the emulsion to make them unstable, e.g. by increasing the surface or interfacial energy.

The demulsifiers used according to the invention have a hydrophilic part and a hydrophobic part. They can be divided into two groups as follows:

Group 1 is a condensate comprising a hydrophobic part and one or more oxyalkylated groups making up the hydrophilic part.

The hydrophobic part is derived from a precursor containing one or more groups, such as hydroxy groups, amino groups, i.e. primary, secondary, tertiary amino groups and quaternary ammonium groups, and halogen groups, which are capable of undergoing a condensation reaction to form the oxyalkylated groups.

The oxyalkylated groups may, for example, have up to 50 oxyalkyl units per group capable of undergoing a condensation reaction, and each such oxyalkylated unit may, for example, have 2 to 6 carbon atoms and may, for example, be ethoxy, propoxy or butoxy. The oxyalkylated units in a particular oxyalkylated group may be the same or different.

An example of a demulsifier from Group 1 is a phenolic resin of the following general formula, which is a precursor for the hydrophobic portion, the hydroxy groups of which have been condensed to form oxyalkylated groups:

wherein R is an aliphatic hydrocarbon group having 3 to 24 carbon atoms, such as 9 or 15, and n is a number from 1 to 20, such as 4 to 10. The hydrocarbon group contains C and H atoms and is connected to the rest of the molecule through a C atom. It may be straight-chain or branched, saturated or unsaturated or alicyclic and may contain one or more heteroatoms (e.g. O, S, N), provided that such heteroatoms do not substantially alter the hydrocarbon nature of the group. Preferably R is an alkyl group.

Such phenolic resins can be prepared by the base-catalyzed oxyalkylation of an alkylphenol/formaldehyde resin that has been prepared by acid catalysis. They are described, for example, in US-A-2,499,367, US-A-3,424,565 and US-A-3,752,657.

The number average molecular weight of such oxyalkylated phenolic resins as measured by gel permeation chromatography (GPC) may be, for example, up to 200,000, such as up to 150,000, preferably up to 50,000, more preferably up to 25,000 and even more preferably up to 10,000.

Another example of an emulsifier from Group 1 is a linear mono- or polyhydroxy compound which is a precursor for the hydrophobic portion, the hydroxy group(s) of which have been condensed to form oxyalkylated groups.

Such linear compounds can be mono- or polyhydroxy alcohols such as mono- or polyalkylene glycols, in which the alkylene groups contain e.g. 1 to 6 carbon atoms, or pentaerythritol or mono- or polycarboxylic acids such as aliphatic fatty acids or adipic acid

Another example of a Group 1 emulsifier is a diglycidyl ether whose epoxy groups have been ring-opened with a hydroxy group, e.g. a polyoxyalkylene such as polyethylene glycol or polypropylene glycol, to form hydroxy groups in addition to the oxyalkylene groups, which themselves can optionally be oxyalkylated to form a branched or cross-linked demulsifier.

Another example of a demulsifier from Group 1 is an oxyalkylated amine (primary, secondary, tertiary or quaternary) which is analogous to the above-mentioned oxyalkylated hydroxy compounds as well as oxyalkylated fatty amines which have been reacted with adipic acid.

Examples of demulsifiers are also described in US-A-4 836 829.

Group 2 is a compound having a sulfonate or sulfonic acid group as the hydrophilic part bonded to a hydrophobic part which may be, for example, a long chain alkyl group. Specific examples are alkylaryl sulfonates.

The demulsifiers used in the present invention can also be characterized by their relative solubility numbers, referred to herein as RSN. The RSN can be correlated with the hydrolipophilic balance (HLB), which for demulsifiers is typically between 8 and 11. The RSN is determined by dissolving 1 g of the demulsifier in 50 ml of acetone and titrating distilled water into the solution until a permanent turbidity occurs. The number of milliliters of water added is the RSN. The RSN range of the demulsifiers used in the present invention is suitably from 4 to 25, preferably to about 20.

Examples of demulsifiers that can be used in the present invention are ethylene oxide/propylene oxide copolymers, p-alkylphenol formaldehyde resins of such copolymers and modifications thereof, polyesteramines, aminoxyalkylates, oxyalkylates, cyclic p-alkylphenol formaldehyde resins and complex modifications thereof, crosslinked polyols such as polyol esters, polymeric esters and resins, chain-extended polyols, oxyalkylated chain-extended polyols, alkoxylated fatty acids and heteropolyols, amines such as oxyalkylated amines (e.g. ethoxylated amines) and polyesteramines, oxyalkylated phenol formaldehyde resins, sulfonates, sulfosuccinic acid esters, oxyalkylated phenols and blocked polyols. The demulsifiers specified above are not necessarily mutually exclusive.

According to the invention, the demulsifiers can be used individually or as mixtures of more than one demulsifier.

ADDITION PRODUCTS OR CONDENSATES

The addition products are formed by an addition reaction as such, and the condensates are formed by a condensation reaction involving an addition of one molecule to another with the elimination of a simple molecule such as water, ammonia or an alcohol. They include materials known in the art for improving the cold flow properties of oils. In this specification, reference to such products and condensates also includes products and condensates produced by a process sequence comprising an addition or condensation reaction, for example an addition product or a condensate which has been subjected to one or more successive further processing steps.

Examples of addition products are one or more copolymers of ethylene and an unsaturated monomer of the general formula

in which R6 is hydrogen or methyl, R5 is a -OOCR8 group in which R8 is hydrogen or a straight or branched chain C1 to C28, more usually C1 to C17 and preferably C1 to C28 alkyl group, or R5 is a -COOR8 group in which R8 is as previously defined but not hydrogen and R7 is hydrogen or -COOR8 as previously defined,

and may comprise other comonomer(s) to e.g. increase to terpolymers or tetrapolymers or higher, where the other comonomer is, for example, an isoolefin such as diisobutylene or isobutylene.

The monomer comprises, when R6 and R7 are hydrogen and R5 is -OOCR8, vinyl alcohol esters of C1 to C29, usually C1 to C5 monocarboxylic acid and preferably C2 to C29, preferably C2 to C5 monocarboxylic acid. Examples of vinyl esters which can be copolymerized with ethylene include vinyl acetate, vinyl propionate and

Vinyl butyrate or isobutyrate, with vinyl acetate being preferred. It is preferred that these copolymers have a number average molecular weight, as measured by vapor phase osmometry, of from 1,000 to 10,000, preferably from 1,000 to 5,000.

Examples of condensates are given below:

An oil-soluble polar nitrogen compound comprising one or more of the compounds (i) to (iii):

(i) an amine salt and/or amide formed by reacting at least one molar proportion of a hydrocarbon-substituted amine with a molar proportion of a hydrocarbon acid having 1 to 4 carboxylic acid groups or its anhydrides, or a condensate as described in EP-A-327 423,

(ii) a chemical compound comprising or including a cyclic ring system, the compound bearing at least two substituents of the following general formula (I) on the ring system

-A-NR¹R² (I)

in which A is an aliphatic hydrocarbon group, which is optionally interrupted by one or more heteroatoms and which is straight-chain or branched, and R¹ and R² are the same or different and each independently of one another is a hydrocarbon group having 9 to 40 carbon atoms, which are optionally interrupted by one or more heteroatoms, where the substituents are the same or different and the compound is optionally in the form of a salt thereof, and

(iii) a condensate of a long-chain primary or secondary amine with a carboxylic acid-containing polymer, as described, for example, in GB-A-2 121 807, FR-A-2 592 387 and DE-A-3 941 561.

With regard to (i), (ii) and (iii) above, the following should be noted.

(i) Esters/amides containing a total of 30 to 300, preferably 50 to 150, carbon atoms may be used. These nitrogen compounds are described in American Patent US-A-4,211,534. Suitable amines are usually long chain primary, secondary, tertiary or quaternary C12 to C40 amines or mixtures thereof, but shorter chain amines may be used provided that the resulting nitrogen compound is oil soluble and therefore they normally contain a total of 30 to 300 carbon atoms. The nitrogen compound preferably contains at least one straight chain C8 to C40, preferably C14 to C24 alkyl segment.

Suitable amines include primary, secondary, tertiary or quaternary, but are preferably secondary. Tertiary and quaternary amines can only form amine salts. Examples of amines include tetradecylamine, cocoamine and hydrogenated tallow amine. Examples of secondary amines include dioctadecylamine and methylbehenylamine. Amine mixtures are also suitable, such as those derived from natural materials. A preferred amine is a secondary hydrogenated tallow amine of the formula HNR¹R², in which R¹ and R² are alkyl groups derived from hydrogenated tallow fat composed of approximately 4% C₁₄, 31% C₁₆ and 59% C₁₈.

Examples of suitable carboxylic acids and their anhydrides for the preparation of the nitrogen compounds include cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2- dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, ethylenediaminetetracarboxylic acid and naphthalenedicarboxylic acid. Generally, these acids have from 5 to 13 carbon atoms in the cyclic portion. Preferred acids useful in the present invention are benzenedicarboxylic acid such as phthalic acid, isophthalic acid and terephthalic acid. Phthalic acid or its anhydride is particularly preferred. The particularly preferred compound is the amide-amine salt formed by reacting one molar portion of phthalic anhydride with two molar portions of dihydrogenated tallow amine. Another preferred compound is the diamide formed by dehydrating this amide-amine salt.

(ii) Preferably, A has 1 to 20 carbon atoms and it is preferably a methylene or polymethylene group.

"Hydrocarbon" means an organic radical composed of hydrogen and carbon and bonded to the rest of the molecule through a carbon atom, which, unless the context indicates otherwise, may be aliphatic, including alicyclic, aromatic, or any combination of the same. It may be substituted or unsubstituted alkyl, aryl, or aralkyl, and may optionally contain unsaturation. Examples where it is substituted are oxy-, halo-, or hydroxyhydrocarbon.

The cyclic ring system may contain homocyclic, heterocyclic or fused polycyclic arrangements, or a system in which two or more such cyclic arrangements are linked together and in which the cyclic arrangements are the same or may be different. When two or more cyclic arrangements are present, the substituents of general formula (I) may be present in the same or different arrangements, preferably in the same arrangement. Preferably the or each cyclic arrangement is aromatic and more preferably a benzene ring. Most preferably the cyclic ring system is a single benzene ring, when it is preferred that the substituents are present in the ortho or meta positions, where the benzene ring may optionally be further substituted.

The ring atoms in the cyclic arrangement or arrangements are preferably carbon atoms, but may, for example, comprise one or more ring N, S or O atoms, in which case or cases the compound is a heterocyclic compound.

Examples of such polycyclic arrangements include

(a) condensed benzene structures such as naphthalene, anthracene, phenanthrene and pyrene,

(b) fused ring structures in which none or not all rings are benzene, such as azulene, indene, hydroindene, fluorene and diphenylene oxide,

(c) "terminally" connected rings such as diphenyl,

(d) heterocyclic compounds such as quinoline, indole, 2,3-dihydromdole, benzofuran, coumarin, isocoumarin, benzothiophene, carbazole and thiodiphenylamine,

(e) non-aromatic or partially saturated ring systems such as decalin (i.e. decahydronaphthalene), α-pinene, cardinene and bornylene, and

(f) three-dimensional structures such as norbornene, bicycloheptane (i.e. norbornane), bicyclooctane and bicyclooctene.

Each hydrocarbon group forming R¹ and R² according to the invention may, for example, be an alkyl or alkylene group or a mono- or polyalkoxyalkyl group. Preferably, each hydrocarbon group is a straight-chain alkyl group. The number of carbon atoms in each hydrocarbon group is preferably 16 to 40, more preferably 16 to 24.

It is also preferred that the cyclic system is substituted with only two substituents of the general formula (I) and that A is a methylene group.

Examples of salts of chemical compounds are acetate and hydrochloride.

The compounds may be conveniently prepared by reducing the corresponding amide, which may be prepared by reacting a secondary amine with the appropriate acid chloride.

(iii) esters of telomer acid and alkanolamines, as described for example in US-A-4,639,256, the reaction product of an amine-containing branched carboxylic acid ester, an epoxide and a monocarboxylic acid polyester, as described for example in US-A-4,631,071.

Further examples of condensates are the following, which are co-additives to improve the cold flow properties of distillate fuels Examples of such co-additives are the following:

COMB POLYMERS

Such polymers are described in "Comb-Like Polymers. Structure and Properties", N.A. Platé and V.P. Shibaev, J. Poly, Sci. Macromolecular Revs., 8, pages 117 to 253 (1974).

Advantageously, the comb polymer is a homopolymer having side chains containing at least 6 and preferably at least 10 atoms, or a copolymer of which at least 25 and preferably at least 40, more preferably at least 50 mol% of the units have side chains containing at least 6 and preferably at least 10 atoms.

Examples are those of the general formula

in the

D = R, CO.OR, OCO.R, R¹CO.OR or OR,

E = H or CH₃ or D or R¹,

G = H or D,

m = 1.0 (homopolymer) to 0.4 (molar ratio),

J = H, R¹ is an aryl group or heterocyclic group or R¹CO.OR,

K = H, CO.OR¹, OCO.R¹, OR¹ or CO₂H,

L = H, R¹, CO.OR¹, OCO.R¹, aryl or CO₂H,

n = 0.0 to 0.6 (molar ratio),

R ≥ C₁₀₀ and

R¹ ≥ C₁.

Another monomer may be terpolymerized if required.

Examples of suitable comb polymers are fumarate/vinyl acetate copolymers, in particular those described in European patent applications 0 153 176 and 0 153 177, esterified olefin/maleic anhydride copolymers, polymers and copolymers of α-olefin/maleic anhydride copolymers, polymers and copolymers of α-olefins, esterified copolymers of styrene and maleic anhydride or fumaric anhydride, and polymers of alkyl esters of itaconic acid or citraconic acid, such as those in which the alkyl groups contain 16 to 18 carbon atoms and the polymer has a number average molecular weight of 1,000 to 20,000.

POLYOXYALKYLENE COMPOUNDS

Examples are polyoxyalkylene esters, ethers, ester/ethers and mixtures thereof, especially those containing at least one, preferably at least two linear, saturated C10 to C30 alkyl groups and a polyoxyalkylene glycol group having a molecular weight of 100 to 5,000, preferably 200 to 5,000, where the alkyl group in the polyoxyalkylene glycol contains 1 to 4 carbon atoms. These materials form the subject of European Patent Publication 0 061 895 A2. Other such additives are described in American Patent US-A-4 491 445.

The preferred esters, ethers or ester/ethers that can be used can be structurally represented by the formula

RO(A)-O-R² in which R and R2 are equal or different and

wherein the alkyl group is linear and saturated and contains 10 to 30 carbon atoms and A is the polyalkylene segment of the glycol in which the alkylene group has 1 to 4 carbon atoms, such as a polyoxymethylene, polyoxyethylene or polyoxytrimethylene group which is substantially linear, a degree of branching with lower alkyl side chains (such as in polyoxypropylene glycol) being tolerated, but it is preferred that the glycol be substantially linear. A may also contain nitrogen.

Suitable glycols are generally linear polyethylene glycols (PEG) and polypropylene glycols (PPG) having a molecular weight of about 100 to 5,000, preferably about 200 to 2,000. Esters are preferred and fatty acids containing 10 to 30 carbon atoms are useful for reacting with the glycols to form the ester additives, it being preferred to use a C18 to C24 fatty acid, particularly behenic acid. The esters can also be prepared by esterification of polyethoxylated fatty acids or polyethoxylated alcohols.

Polyoxyalkylene diesters, diethers, ethers/esters and mixtures of these are suitable as additives, with diesters being preferred for use in narrow boiling distillates when small amounts of monoethers and monoesters (often formed in the manufacturing process) may also be present. It is important for additive performance that a larger amount of the dialkyl compound be present. In particular, stearic or behenic diesters of polyethylene glycol, polypropylene glycol or polyethylene/polypropylene glycol mixtures are preferred.

Examples of other compounds of this general category are those described in Japanese Patent Publications Nos. 2-51477 and 3-34790 (Sanyo) and EP-A-117 108 and EP-A-326 356 (NOF).

HYDROCARBON POLYMERS

Examples are those of the following general formula

in which T = H or R¹,

U = H, T or aryl,

v = 1.0 to 0.0 (molar ratio) and

w = 0.0 to 1.0 (molar ratio),

wowwhere R¹ is alkyl.

These polymers can be prepared directly from ethylenically unsaturated monomers or indirectly by hydrogenation of the polymer prepared from monomers such as isoprene, butadiene etc.

A particularly preferred hydrocarbon polymer is a copolymer of ethylene and propylene having an ethylene content which is preferably between 20 and 60% (w/w) and which is usually prepared using homogeneous catalysts.

SULFUR CARBOXYLIC COMPOUNDS

Examples are those described in EP-A-0 261 957, wherein the use of compounds of the general formula

is described in the

R¹ and R² are alkyl, alkoxyalkyl or polyalkoxyalkyl with at least 10 carbon atoms in the main chain,

R³ is hydrocarbon and each R³ may be the same or different, and R⁴ is of no significance or C₁ to C₅ alkylene, and in

the carbon-carbon (C-C) bond is either a) ethylenically unsaturated when A and B can be alkyl, alkenyl or substituted hydrocarbon groups, or b) is part of a cyclic structure which can be aromatic, polynuclear aromatic or cycloaliphatic, it being preferred that X-R¹ or Y-R² have between them at least three alkyl, alkoxyalkyl or polyalkoxyalkyl groups.

Multi-component additive systems can be used and the ratios of additives to be used depend on the fuel to be treated.

OIL

The oil may be a crude oil, i.e. an oil coming directly from drilling and prior to refining, with the compounds of the invention being suitable for use as flow improvers or dewaxing aids therein.

The oil may be a fuel oil, suitably a middle distillate fuel oil. Such distillate fuel oils generally boil in the range 110°C to 500°C, e.g. 150°C to about 400°C. The fuel oil may be atmospheric or vacuum distillate, cracked gas oil or a mixture in any proportion of straight or thermally and/or catalytically cracked distillates. The most common petroleum distillate fuels are kerosene, jet fuels, diesel fuels, heating oils and heavy fuel oils. The heating oil may be a straight atmospheric distillate or it may contain small amounts, e.g. up to 35% by weight, of vacuum gas oil or cracked gas oils or both.

The fuel oil may be an animal oil, vegetable oil or mineral oil, and may also be synthetic. It may also contain other additives such as stabilizers, dispersants, antioxidants and corrosion inhibitors. In addition, the fuel oil may contain a sulfur concentration of 0.2% or less by weight of the fuel, preferably 0.05% or less, and more preferably 0.01% or less.

The concentration of the demulsifier in the oil may, for example, be up to 2,000 ppm additive (active ingredient) by weight of the fuel, but preferably not greater than 50 ppm when used in combination with other additives, with a preferred lower limit being 5 ppm. The concentration of such other additives may be from 10 to 2,000 ppm (active ingredient) by weight of the fuel, preferably from 25 to 500 ppm, more preferably from 100 to 200 ppm. When used alone, the demulsifier may have a concentration of up to 1,000 ppm by weight, preferably up to 500 ppm, more preferably up to 300 ppm.

The additive or additives should be soluble in the oil to a level of at least 1 000 ppm by weight of the oil at ambient temperature. However, at least some of the additive may come out of solution near the cloud point of the oil to modify the wax crystals that form.

CONCENTRATES

The concentrates of the invention are useful as a means for introducing the additive into bulk oil, such as distillate fuel, which introduction may be accomplished by methods known in the art. The concentrates may also contain other additives as necessary, and they contain preferably 3 to 75% by weight, more preferably 3 to 60% by weight, most preferably 10 to 50% by weight of the additives, preferably in solution in oil. Examples of the carrier liquid are organic solvents, including hydrocarbon solvents such as petroleum fractions such as naphtha, kerosene and fuel oil, aromatic hydrocarbons containing aromatic fractions (eg Solvesso (trade name)), and paraffinic hydrocarbons such as hexane, pentane and isopraffins, and include mixtures of the above. The carrier liquid must of course be selected with regard to its compatibility with the additive and with the fuel.

The additives of the invention can be introduced into bulk oil by methods other than those known in the art. If co-additives are required, they can be introduced into the bulk oil at the same time as the additives of the invention or at a different time.

EXAMPLES

The invention is specifically described below using the following examples.

ADDITIVE

The following additives were used and are indicated using the numbers assigned to them:

1. DEMUSLIFIERS

1: A linear adipate prepared by esterification of adipic acid with polypropylene glycol under acidic conditions to form an adipate ester.

2: A product prepared by oxyalkylating dipropylene glycol under basic conditions to form an intermediate which was reacted with a diglycidyl ether epoxy resin.

3: An oxyalkylated polyether resin prepared by oxyalkylating dipropylene glycol under basic conditions to form an intermediate similar to that obtained in the preparation of Demulsifier 2, which intermediate was reacted with a diglydidyl ether epoxy resin to give a product which was further oxyalkylated with propylene oxide.

2. ADDITIVE

4: An ethylene/vinyl acetate copolymer having a number average molecular weight of 5,000 as measured by GPC (gel permeation chromatography) and containing 13.5 wt.% vinyl acetate.

5: An ethylene-vinyl acetate copolymer having a number average molecular weight of 3,300 as measured by GPC and containing 36 wt% vinyl acetate.

6: An N,N-dialkylammonium salt of 2-N¹,N¹-dialkylamidobenzoate which is the reaction product of reacting one mole of phthalic anhydride with two moles of dihydrogenated tallow amine to form a half-amide/half-amine salt.

7: An itaconate polymer having a number average molecular weight of about 4,000 as measured by GPC, obtained by polymerizing a monomer in cyclohexane solvent using a free radical catalyst, wherein the monomer contained linear alkyl groups having 18 carbon atoms.

8: A copolymer of styrene and esterified fumaric acid, in which the alkyl groups have 14 carbon atoms, the copolymer having a number average molecular weight of 15,000 as measured by GPC and proportions of styrene and esterified fumaric acid in the ratio of 1:1 (mole:mole).

9: A demulsifier consisting of an alkylated phenol/formaldehyde resin condensate prepared by acid-catalyzed condensation of a C9-alkylated phenol with formaldehyde followed by oxyalkylation under basic conditions with ethylene oxide.

10: An ethylene/vinyl acetate copolymer having a number average molecular weight of 3,300, as measured by GPC, and containing 29 wt.% vinyl acetate.

FUELS

The following fuels were used:

Key: WAT is the paraffin appearance temperature as measured by differential scanning calorimetry (DSC).

ASTM D-86:

90-20 is the difference between the temperatures at which 90 and 20% of the fuel (by volume) has been distilled.

FBP-90 is the difference between the final boiling point of the fuel and the temperature at which 90% of the fuel (by volume) has been distilled.

FBP, IBP are the final and initial boiling points. Cloud point CP as measured by IP 219/82.

TESTED

The additives were dissolved in the fuels and the following tests were conducted on untreated fuel and on fuel treated with additives to measure the following to test the effectiveness of the tested additives as filterability improvers in distillate fuels.

COLD FILTER PLUGGAGE POINT (CFPP)

This test was described in detail in "Journal of the Institute of Petroleum", Volume 52, Number 510, June 1966, pages 173 to 285. This test is designed to correlate with the cold flow of a middle distillate fuel oil in automotive diesel engines.

SIMULATED FILTER CLOGGING POINT (SFPP)

This test was carried out according to the procedure essentially described in EP-A-0 403 097 and is a variation of the CFPP test.

PARAFFIN APPEARANCE TEMPERATURE (WAT)

This is a measure of the onset of crystallisation and therefore of the cloud point and was determined using differential scanning calorimetry (DSC). Therefore, a small sample (25µl) of the test fuel was cooled at 2ºC/min from a temperature at least 30ºC above the expected cloud point of the fuel. An exotherm was observed as crystallisation began in the sample and the WAT was determined by an extrapolation technique using a Mettler TA 20008 differential scanning calorimeter.

RESULTS

The results are shown in the following tables. Table 1

Key: Fuel A was used in each of Examples 1 to 6.

Additive X was a mixture of Additives 4, 5, 6, 7 and 8 in a weight ratio of 1:3:2:3:2. Table 2

Key: Delta WAT is the difference in WAT between the untreated and the treated fuel and therefore a measure of the driving point depression.

The results of Table 1 demonstrate the synergism of demulsifier additives (i.e., 1 and 2) with other additives in filterability tests, and those of Table 2 demonstrate the effectiveness of demulsifier additives (i.e., 2 and 3) in producing cloud point depression. Table 3

Examples 13 to 18 were run on Fuel C. The results show that the SFPP performance was improved when the demulsifier (Additive 9) was used in combination with one or both of the cold flow additives (Additives 10 and 6) as in Examples 15 and 16.

Claims (13)

1. Additive composition, which (i) one or more non-metallic flow-enhancing oil-soluble addition products or condensates capable, either jointly or individually, of improving one or more cold flow properties of crude oil or fuel oil, and (ii) non-metallic, oil-soluble demulsifier for crude oil or fuel oil-water emulsions, the demulsifier having a hydrophobic part and a hydrophilic part and being selected from the following groups 1 and 2, wherein group 1 is a condensate comprising as the hydrophobic part a part derived from a precursor having one or more groups capable of a condensation reaction to form oxyalkylated groups, which is bonded to one or more oxyalkylated groups making up the hydrophilic part, and group 2 is a compound having a sulfonate or sulfonic acid group as the hydrophilic part bonded to the hydrophobic part, provided that component (i) is not a combination of a substituted succinic acid derivative and an ethylene/vinyl acetate copolymer. 2. Composition according to claim 1 in admixture with a major proportion of crude oil or fuel oil, the composition making up a minor proportion. 3. A composition according to claim 1 dispersed in a liquid medium compatible with crude oil or fuel oil to form a concentrate. 4. Use of an additive composition according to claim 1 for improving the cold flow properties of crude oil or fuel oil. 5. Composition or use according to any one of the preceding claims, wherein the demulsifier is from group 1, wherein the hydrophobic portion is derived from a precursor having one or more hydroxy groups, one or more of these hydroxy groups having been condensed to form the oxyalkylated groups attached thereto. 6. Composition or use according to claim 5, wherein the precursor has the general formula: in which R is an aliphatic hydrocarbon group having 3 to 24 carbon atoms and n is a number from 4 to 20. 7. A composition or use according to claim 5, wherein the precursor is a linear mono- or polyhydroxy compound, one or more of the hydroxy groups of which have been condensed to form the oxyalkylated groups. 8. Composition or use according to any one of claims 1 to 5, wherein the demulsifier is from group 1, wherein the hydrophobic portion is derived from a precursor having one or more primary, secondary or tertiary amino groups or quaternary ammonium groups and one or more of these groups has been condensed to form the oxyalkylated groups attached thereto. 9. A composition or use according to any one of the preceding claims, wherein the demulsifier is from group 1, wherein the or each oxyalkylated group has up to 50 oxyalkyl units per group capable of condensation reaction, each such oxyalkylene unit having 2 to 6 carbon atoms. 10. A composition or use according to claim 2 or claim 4 or any claim dependent thereon, wherein the oil is a fuel oil and the demulsifier is present therein in a weight proportion not greater than 50 ppm. 11. A composition or use according to claim 2 or claim 4 or any claim dependent thereon, wherein the oil is a middle distillate fuel oil. 12. Composition or use according to any one of the preceding claims, wherein the flow-enhancing addition product or condensate is selected from one or more of: (a) ethylene-vinyl ester copolymer, (b) comb-like polymer, (c) polar nitrogen-containing compound or compounds comprising an amine salt or an amide or both, obtained by reacting at least one molar proportion of hydrocarbon-substituted amine with a molar proportion of Hydrocarbon acid having 1 to 4 carboxylic acid groups or its anhydride has been formed. 13. Use of an additive composition according to any one of the preceding claims for improving the cold flow properties of a fuel oil, wherein the demulsifier has a relative solubility number (RSN) of 4 to 25, wherein the RSN has been determined by dissolving 1 g of the demulsifier in 50 ml of acetone and titrating distilled water until a permanent turbidity occurs, and the RSN is the number of ml of water added.