NO122715B - - Google Patents

Description

Fuel composition containing a pour point depressant.

The present invention relates to a fuel composition

containing pour point depressant.

Although various pour point depressants are known and have been used, they have so far only been satisfactory in connection with middle distillate fuels. It has been difficult to find a satisfactory pour point depressant for shale oils, crude oils, residual fuels and various types of distillates. It has now been discovered that certain polymers can be used as effective pour point depressants in certain hydrocarbons, e.g. residual fuels or crude oils.

The pour point of a fuel or a crude oil is of relatively great practical importance. They must be below a minimum temperature at which the crude oil or fuel is stored, transported and used because this avoids difficulties when the fuel or oil is used in practice.

British patent no. 1 068 000 describes a fuel containing a small amount of a copolymer of ethylene and propylene where the ethylene makes up 80 mole percent and preferably 60 - 75 mole percent. The upper limit of 80 mole percent is stated as critical presumably because the patent relates to a special application of the fuel. It has now been discovered that it is not only possible to use higher mole percentage amounts of ethylene, but that it is advantageous to use such higher amounts.

According to the present invention, it is thus provided

a fuel composition containing a pour point depressant and this fuel composition is characterized by the fact that it consists of a larger amount by weight of a residual fuel, a flash distillate fuel, a shale oil or a crude oil, as well as a smaller weight part of an oil-soluble copolymer of ethylene and one or more substituted ethylenes, where any linear side chains present in the substituted ethylene contain less than 18 carbon atoms, the copolymer containing 82-99 mole percent ethylene, provided that the copolymer has an average molecular weight of more than 800 and provided that it is not a dipolymer with an average molecular weight of more than 3000 of ethylene and a vinyl or hydrocarbyl substituted vinyl ester of a carboxylic acid,

the copolymer possibly also comprising a third comonomer which is an unsaturated ester of a saturated carboxylic acid, provided that any linear side chains present in this third comonomer contain less than 18 carbon atoms.

A residual fuel is defined as a fuel containing residues from a distillation of a crude oil or a shale oil or mixtures of these. Usually, the residual fuel (hereinafter only referred to as "the fuel") will contain from approx. 10 to approx. 100%, e.g. from 35 to about 100 weight percent residue, preferably boiling above 315°C at atmospheric pressure, and will usually have kinematic viscosities varying from 10 to 3500 cS at 37.7°C. However, the viscosity of certain waxy fuels can be difficult to measure accurately at 37-7°C, and it is well known that the viscosity of such fuels is measured using the viscosity at a higher temperature. The viscosity at 37°7°C is then obtained by extrapolation when using a R.E.F.U.T.A.S, viscosity-temperature kernel.

The extrapolated kinematic viscosities will then fall in the pre-explored range at 37.7°C R.E.F.U.T.A.S, temperature/viscosity chart designed by CI. Kelly, M.S.C. TECH. , F.I.C., M. Inst., P.T., A.M.I.A.E. , Baird & Tatlock (London) Ltd. It is preferred that the kinematic viscosities of the fuels should lie between 15 and 1500 cS at 37-7°C. Fuels where at least 30%, preferably at least 60% by weight of the fuel boil over approx. 260°C at atmospheric pressure.

The present fuel can therefore be used in connection with light, medium and heavy fuels as well as bunker oils, whose viscosities usually vary from 15 - 2000 cS at 37•7°G, but where the maximum viscosity will usually however be approx. 1500 cS at 37.7°C. Examples of suitable fuels are described in Pt 3 Industrial and Marine Fuels of BS2689: 1957.

Suitable fuels also include "flash distillate fuels" which are defined as distillate fuels produced by a flash distillation at reduced pressure of the residue obtained by a distillation of crude oils at atmospheric pressure. Such fuels are produced by distilling a crude oil at atmospheric pressure to a bottom temperature of approx. 175°C, thereby obtaining an atmospheric residue such as

by means of "flashing" under greatly reduced pressure is divided into a "■flashed" distillate and a vacuum residue. During such a flash distillation, a preheated supply will be continuously fed into a flash chamber where evaporation takes place under constant equilibrium conditions. Gaseous and liquid products are continuously removed. During this flashing, essentially no fractionation takes place, and the temperature used is limited by possible cracking and carbonisation. These side reactions usually start to occur if the temperature rises above approx. 205°C. The flashing is carried out at greatly reduced pressure. to ensure a high distillate yield from a given atmospheric residue.

You can also use the crude oil from which the fuel is produced, or a shale oil or mixtures of these. The crude oil can be a waxy crude oil, and usually the pour point of such crude oils will be higher than -23.3°C.

The substituted ethylene is preferably an ethylenic unsaturated acid or a salt thereof, an anhydride, an ester of an unsaturated carboxylic acid, an amine, a hydroxy compound, a nitrile, an amide or an imide, and if in all these compounds there are saturated side chains , then these must contain less than l8 carbon atoms. The substituted ethylenes should preferably contain from 3 to 40 carbon atoms per molecule.

Suitable ethylenic unsaturated monocarboxylic acids thus include acrylic acid, methacrylic acid, vinylacetic acid, angelic acid, tiglic acid, undecyl acid, oleic acid and elaidic acid. Suitable ethylenically unsaturated dicarboxylic acids include maleic acid, fumaric acid, meaconic acid, citraconic acid, itaconic acid, trans- and cis-glutaconic acids. You can also use other ethylenically unsaturated polyacids, e.g. cis- and trans-aconitinic acids.

Examples of suitable esters of unsaturated acids, e.g. of those mentioned above, are C-3 to C-3 alkyl esters (preferably straight-chain alkyl esters) of the above-mentioned acids, and either mono- or diesters of unsaturated dicarboxylic acids can be used. You can also use esters with branched side chains, e.g. oxoesters of ethylenically unsaturated esters, provided that these do not contain linear side chains containing more than 17 carbon atoms. One can thus use methyl, ethyl, butyl, isopropyl, n-butyl, octyl, 2-ethylhexyl, decyl, dodecyl, heptadecyl esters of acrylic or methacrylic acids or mono- or dimethyl-, ethyl, n-butyl, hexyl or dodecyl esters of fumaric acid, maleic acid or citraconic acid.

Suitable ethylenically unsaturated amides include those corresponding to the above-mentioned acids, i.e. both mono- and polyamides, while suitable anhydrides and imides are those corresponding to the above-mentioned acids. Suitable salts can be ammonium or metal salts, e.g. sodium or potassium salts of the above-mentioned acids. One can thus use maleic anhydride, maleimide, acrylamide, methacrylamide, citraconamides, itaconamide, n-alkyl maleimides containing up to 17 carbon atoms in any linear side chains present.

Examples of suitable ethylenically unsaturated hydroxy compounds include monoalcohols, polyols and phenolic compounds. Suitable alcohols that can thus be used are allyl alcohol, but-l-en-l-ol, hex-2-en-l-ol, hydroxyethyl methacrylate, eicos-4-en-l-ol, 1-methyl-hex-2 -en-l-ol, 7-ethyleicos-2-en-l-ol, or 1-1-dimethyl-hex-2-en-l-ol, diols include e.g. but-2-ene-1,4-diol. Examples of suitable phenols include phenols with an unsaturated side chain, e.g. para-allyl-phenol (chavicol).

Suitable ethylenically unsaturated amines and nitriles include allylamine, allyl cyanide, 1-amino-but-2-ene, 1-amino-hex-5-ene, 1-amino-nona-decen-18-ene, 1-amino-but-3 -ene, dimethylaminoethyl methacrylate, dimethylaminomethyl acrylate, diethylaminomethyl methacrylate, acrylonitrile and meth-acrylonitrile.

Other examples of suitable substituted ethylenes include alpha-olefins, alkenyl alkyl ethers, styrene or hydrocarbyl substituted styrene, alkenyl halides (eg a vinyl or allyl halide), unsaturated aldehydes or unsaturated ketones. Examples of alpha-olefins are prop-1-ene, but-1-ene, hex-1-ene, dec-1-ene and dodec-1-ene, nonadec-1-ene, while examples of suitable alkenyl alkyl ethers are vinyl methyl ether, vinyl ethyl ether, vinyl n-octyl ether, vinyl n-heptadecyl ether, allyl methyl ether, allyl n-hexyl ether and allyl n-heptadecyl ether.

Suitable hydrocarbyl substituted styrenes include alkyl (e.g. methyl or ethyl) substituted styrenes where the substituents are in the benzene ring or linked to the alpha carbon atom of the vinyl group into the benzene ring, e.g. o-methylstyrene, α-ethylstyrene, p-methylstyrene, p-ethylstyrene, and p-n-heptadecylstyrene.

Examples of vinyl or allyl halides are vinyl chloride, vinyl bromide or allyl chloride.

Suitable unsaturated aldehydes and ketones include acrolein, methyl vinyl ketone, mesityl oxide, ethyl vinyl ketone, n-heptadecyl vinyl ketone and cinnamaldehyde.

Further examples of suitable substituted ethylenes are unsaturated esters of saturated carboxylic acids (provided that any linear side chains present do not contain more than 18 carbon atoms). These include vinyl or allyl esters of C-1 to C-3 monocarboxylic acids, e.g. vinyl acetate, allyl acetate, allyl propionate, vinyl butyrate, allyl stearate and isopropenyl acetate. With respect to these unsaturated esters of saturated carboxylic acids, and if the average molecular weight of the copolymer is above about 3000, then such esters must be copolymerized not only with ethylene, but also with another monomer that is not a vinyl or hydrocarbyl substituted vinyl ester of a carboxylic acid, eg some of the previously mentioned monomers, i.e. the ester is a third copolymer.

Examples of other substituted ethylenes that can be used are the following: vinyl-substituted heterocyclic compounds, e.g. N-vinyl-pyrrolidone, vinylpyridine, N-vinyl-carbazole, vinyl derivatives of silicones and phosphorus compounds, e.g. diethoxyvinylsilane, diethylvinylphosphonate, vinyl isothiocyanate, hydrocarbylvinyl sulfides, sulfoxysides and sulfones or vinylene carbonate.

The ethylene can of course be copolymerized with two or more of the above-mentioned monomers, e.g. vinyl acetate with acrylic acid, methacrylic acid, their metal salt amides or nitriles, a vinyl halide with vinyl methyl ether or acrylic acid, or N-vinyl pyrrolidone with methyl vinyl ketone

or vinyl methyl ether.

The resulting polymer should contain from 99 to 82 mole percent, preferably from 97 to 86 mole percent ethylene. This is substantially equivalent to the copolymer containing 95 to 40 weight percent ethylene.

A method for producing these copolymers comprises feeding said monomers into a tube-shaped reactor which has been previously purged with nitrogen. A smaller amount of oxygen, usually from 0.005 to 0.05 weight percent based on the weight of the ethylene present, is also fed into the reactor. Alternatively, instead of oxygen alone, a peroxide initiator can be used, e.g. di-t-butyl peroxide or a mixture of peroxides and oxygen. Furthermore, a solvent can be used in the reaction (e.g. benzene, water, heptane, cyclohexane, acetone, methanol or t-butyl alcohol). The pressure is kept at between 60 and 2700 atmospheres, preferably between 135 and 2000 atmospheres: The temperature is kept at between 40° and 300°C, preferably between 70° and 250°C.

Said copolymers can also be produced by batch-wise processes. Such methods require a solvent for the reactants, and as such one can e.g. use toluene, hexane, benzene, acetone, cyclohexane, t-butyl alcohol or water.

The reaction initiator can be any peroxide compound, e.g. di-t-butyl peroxide, lauroyl peroxide or azo compound, e.g. azobisisobutylonitrile. The temperature of the polymerization reaction depends on the particular peroxide initiator used, and should be sufficient to obtain a proper decomposition of the initiator. Such a temperature would normally lie somewhere between 40° and 300°C. For di-tert-butyl peroxide, the most suitable temperature is somewhere between 130° and 160°C, while for lauroyl peroxide a temperature between 60° and 120°C is most suitable, the pressure should be between 60 and 1000 atmospheres, preferably between 75 °g 667 atmospheres. The autoclave or similar equipment containing the solvent, the initiator and the substituted ethylene is purged with nitrogen and then with ethylene to add a sufficient amount of ethylene to provide the desired pressure when heated to the desired reaction temperature. During the polymerization, additional ethylene is added to keep the pressure at the desired level. Further amounts of the initiator and/or the solvent and/or the substituted ethylene can further be added during the reaction. After the reaction is finished, free solvent and unreacted monomers are removed by distillation or another

suitable method, whereby the desired polymer is recovered.

The copolymers that can be used in the present invention have an average molecular weight of from 1,000 to 60,000, e.g. over 3,000 or • over approx. 3500 as measured by vapor phase osometry (using Mechrolab Vapor Phase osometer model 301A) and/or membrane osometry (using Mechrolab membranosometer model 501). The average molecular weight of copolymers used in the present invention should preferably be between 1,500 and 30,000, more particularly between 4,000 and 20,000. It is understood that the average molecular weight of these copolymers will depend on the pressure, the temperature and the - transition compound used during the polymerization.

The amount of the copolymer used should preferably be between 0.0001 and 10%, e.g. between 0.0005 and 0.5 percent by weight based on the weight of the residual fuel, shale oil, crude oil or flash distillate.

The copolymer can also be fed down the borehole to the crude oil to prevent the formation of paraffin deposits, or to dissolve existing deposits on the sides of the borehole. For this purpose, the copolymer can either be fed continuously or discontinuously. The copolymer can also be added to crude oils or residues above ground to facilitate their movement through pipelines. The copolymer can e.g. is added to any North African crude oil to lower their pour point so that they can be pumped more easily.

The copolymers used can also be used in certain types of fuel such as e.g. light fuel oils, where their presence reduces the size of the wax particles that are secreted. Light fuel oils have a certain tendency to create problems due to this wax separation. The wax that is present as a solid phase in such fuels at normal storage temperatures and eventually agglomerates particles of such a size that they can easily block the filter in the burners, which results in a loss of fuel to the burner, and that the flame can go out . Copolymers used in the present invention can be added to fuels and crude oils and can thereby reduce the size of the wax particles, so that the fuels can be fed through the filters more easily.

The addition of the above-mentioned copolymers in fuels, crude oils etc. can be facilitated by first preparing copolymer concentrates in suitable hydrocarbon mixtures, or in water emulsions. Examples of suitable solvents are those containing large amounts of aromatic hydrocarbons, e.g. toluene, xylene, or a kerosene extract of the type that contains large amounts of aromatic compounds, and which is separated from a crude fraction of the kerosene by liquid sulfur dioxide extraction. Other suitable solvents are waxes of the type obtained without purification or refining from dewaxing processes for lubricating oils. These types of wax will usually have melting points between 20° and 62°C and oil content from 5-50% by weight.

The copolymers used can be used in fuels, crude oils, fuels etc. together with other additives of the type that are usually used in fuels, e.g. rust inhibitors, demulsifiers, corrosion inhibitors, antioxidants or dispersants, or other pour point depressants .

Example 1

Copolymers of ethylene and substituted ethylenes were prepared as follows: A 1 liter stainless steel autoclave equipped with a magnetic stirrer was charged with benzene and then purged with nitrogen and then with ethylene. The autoclave was then heated and pressurized with ethylene. A small amount of the substituted ethylene used was then quickly introduced into the autoclave by means of a metering pump. A solution of 12.5% by weight lauroyl peroxide in benzene was then added to the autoclave for a certain period of time. At the same time, a smaller amount of substituted ethylene was added during the same period of time. The temperature and pressure in the autoclave were kept essentially constant during the reaction. After the peroxide addition was complete, the reaction mixture was cooled and the pressure was reduced. Free solvent and unreacted monomers were removed by stripping, thereby obtaining the desired copolymers in the autoclave.

Precise reaction conditions for each individual copolymer are indicated in Table I.

Some of the copolymers produced were added in amounts corresponding to a 0.1% by weight concentration to a light fuel oil-containing residue with an upper pour point of +10°C (determined by Institute of Petroleum method 15/67), a viscosity of 26.7 cS at 50° C and 4.3.7 cS at 37«7°0, a carbon content of 86.3 weight percent and a hydrogen content of 12.4 weight percent and a specific gravity at 15°C of 0.921.

The upper pour point as determined by Institute of Petroleum method 15/67 was measured for each mixture of the copolymer and the light fuel oil.

The results are given in Table I, and it appears that the upper pour point for the mixture of light fuel oil and the copolymer was in each case reduced from the upper pour point of +10°C for the fuel oil alone.

Some of the copolymers produced were added in amounts corresponding to a 0.15 percent by weight concentration to a residual fuel produced from a North African crude oil by distillation to a final vapor temperature of 375°C. This fuel had an upper pour point of 37.7°C as determined by Institute of Petroleum Method 15/67, a viscosity of 325.5 cS at 50°C, a carbon content of 86.6 weight percent and a hydrogen content of 12.8 weight percent. The kinematic viscosity of this fuel could not be determined at 37-7°C. It essentially consisted of 100% residue.

Some of the copolymers produced were added in amounts corresponding to a concentration of 0.05% by weight to a North African crude oil with an upper pour point of 0.5°C, a density (°API) of 40.2 and a kinematic viscosity at 37.7°C of 3.6 cS.

The results from these mixtures of residual fuel or crude oil with said copolymers are shown in Table I, and it appears that the upper pour point for the individual mixtures was in each case reduced from the upper pour points of 43.3° and 0.5°C (as this could be determined by Institute of Petroleum method 15/67).

Example 2

Certain commercially available ethylene/ethyl acrylate and ethylene/isobutyl acrylate copolymers were added in amounts corresponding to a

0.02 weight percent concentration to a light fuel oil of the type described in example 1. The results given in Table II below show that the upper pour points for mixtures of said oil and copolymer are lower than that found in the oil alone. (+10°C).

Example 3

Various ethylene/substituted ethylene copolymers were produced in an autoclave essentially by the method described in example 1, and they were added to light fuel oils and residual fuels of the type described in example 1, as well as to a crude oil with an upper pour point of +24°C', a viscosity of 5«73 cS at 50°C, as well as an extrapolated viscosity at 37«7°c of 7•5^ cS and which contained 86.5 weight percent carbon and 13.1 weight percent hydrogen.

The upper pour point for the residual oil as well as the crude oil before and after addition of the copolymer was measured by Institute of Petroleum method 15/67. The upper pour point of the light fuel oil before and after addition of the copolymer was determined by a modified method. In this modified method, a sample of the oil was heated to 93°C, removed from the bath and cooled to 48.8°C. The sample was then placed in a dressing bath at a temperature of -34 C and cooled to - TJ. 7 C. The sample was then removed from the bath, reheated to 93°C using a 95°5°^>°g bath after being at this temperature for approx. 1/2 hour it was removed and air-cooled to 32.2°C. The sample was then placed in a bath whose temperature was -1.1°C, and the solidification point was then measured according to Institute of Petroleum method 15/67. The pour point for the light fuel oil in this method was +0.5°C.

The reaction conditions and the obtained pour points are given in Table III.

Example 4

Preparation of copolymers

Five different ethylene/vinyl acetate/methacrylic acid copolymers were prepared, each by a batch process, using different amounts of vinyl acetate and methacrylic acid.

A 1 liter stainless steel autoclave equipped with a magnetic stirrer was charged with 150 ml of benzene and 15 ml of a mixture of 99-5 volume percent vinyl acetate and 0.5 volume percent methacrylic acid. The autoclave was then purged with nitrogen and then with ethylene, after which the autoclave was heated to 80°C and pressurized with ethylene to a pressure of 200 atmospheres. 150 ml of a mixture of 99.5 volume percent vinyl acetate and 0.5 volume percent methacrylic acid was added via a pump over the course of 6 hours. At the same time, a solution of 8 g of lauroyl peroxide in 92 ml of benzene was added to the reactor over the course of 6.5 hours. The temperature was maintained at 80°C and the pressure at 200 atmospheres during the reaction. After the lauroyl peroxide addition was complete, the reaction mass was cooled and the pressure was reduced. Free solvent and unreacted monomers were removed by stripping, whereby copolymer 1 was obtained. Copolymers 2, 3, 4 °g 5 were prepared in the same way by using the reaction conditions and the additions indicated in Table IV.

Copolymers 1, 2, 3 > 4 °g 5 had the following properties.

Polymer properties.

25 percent by weight copolymer concentrations in toluene were prepared by using the above-mentioned copolymers from 1 to 5% g of these concentrates were used to prepare mixtures of copolymers and light fuel oils and residual fuels as described in example 1.

With different concentrations of polymers 1, 2, 3, 4 and

5, the pour point reduction was measured (so that the pour point could be determined by Institute of Petroleum Method 15/67), and this was compared with the pour point of the pure oils.

Example V

In this example, four copolymers were used, and these were added in different concentrations to two different fuels and a crude oil.

The four copolymers were random ethylene/vinyl acetate/methacrylic acid copolymers with the properties indicated in Table VT.

Remarks on table VI

(1) Molecular weight determined in toluene at 65°C using a Mechrolab membranosometer model 501. (2) Molecular weight determined in toluene at 37°C using a Mechrolab vapor phase osometer model 301A.

25 percent by weight copolymer concentrates in petroleum extracts were prepared, and these concentrates were used to prepare mixtures of copolymers and the light fuel oil and the residual fuel described in Example 1 as well as a crude oil (Table VII).

The crude oil was a North African crude oil with an upper pour point of +0.5°C (as determined by the Institute of Petroleum Method 15/67), a density in °API of 4-0.2, and a kinematic viscosity at 37.7°C of 3.6 cS.

Claims (25)

1. Fuel composition containing a pour-point depressant, characterized in that it consists of a larger amount by weight of a residual fuel, a flash distillate fuel, a shale oil or a crude oil, as well as a smaller weight part of an oil-free equal copolymer of ethylene and one or more substituted ethylenes, where any linear side chains in the substituted ethylene contain less than 18 carbon atoms, where the copolymer contains 82 - 99 mole percent ethylene, provided that the copolymer has an average molecular weight of more than 800 and provided that it does not is a dipolymer with an average molecular weight of over 3000 of ethylene and a vinyl- or hydrocarbyl-substituted vinyl ester of a carboxylic acid, the copolymer possibly also comprising a third comonomer which is an unsaturated ester of a saturated carboxylic acid, provided that any linear side chains present in this third comonomers contain less than l8 carbon atoms. 2. Composition according to claim 1, characterized in that it contains 35 - 100 weight percent residual oil. 3. Composition according to claim 1 or 2, characterized in that it has a kinematic viscosity from 10 - 3500 cS at 37.7°C, preferably between 15 and 1500 cS at 37.7°C. 4. Composition according to any of the aforementioned requirements, characterized in that at least 60 percent by weight of the fuel boils above 260°C at atmospheric pressure. 5. Composition according to any of the aforementioned claims, characterized in that the copolymer is derived from ethylene and an ethylenically unsaturated mono- or di-carboxylic acid, an anhydride, a metal salt, an amide or an imide of these, preferably acrylic or methacrylic acids or their metal salts or amides. 6. Composition according to any of claims 1 - 4> characterized in that the copolymer is derived from ethylene and a C-^- to C-^y ester of acrylic or methacrylic acid, preferably methyl, ethyl, isopropyl or octyl esters of acrylic or methacrylic acids. 7. Composition according to any one of claims 1-4, characterized in that the copolymer is derived from ethylene and an α-olefin, styrene or a hydrocarbyl-substituted styrene where the alkyl group is linked to the benzene ring or to the oc-carbon atom in the vinyl group closest to the benzene ring, preferably a methyl- or ethyl-substituted styrene. 8. Composition according to any one of claims 1 - 4> characterized in that the copolymer is derived from ethylene and a vinyl or allyl halide. 9. Composition according to any one of claims 1-4, characterized in that the copolymer is derived from ethylene and an alkenyl alkyl ether, preferably vinyl methyl ether or vinyl ethyl ether. 10. Composition according to any one of claims 1 - 4>, characterized in that the copolymer is derived from ethylene and C-^- to C-^y alkyl esters of either fumaric acid, maleic acid, citraconic acid, itaconic acid, acrylic acid or methacrylic acid, preferably hexyl- or the dodecyl esters of fumaric or maleic acid. 11. Composition according to any one of claims 1-4> characterized in that the copolymer is derived from ethylene and an unsaturated aldehyde, or an unsaturated ketone, preferably from acrolein or methyl vinyl ketone. 12. Composition according to any of claims 1-4, characterized in that the copolymer is derived from ethylene and either N-vinyl-pyrrolidone, vinyl-pyridine, N-vinyl-carbazole, vinyl-isothiocyanate or vinylene-carbonate. 13. Composition according to any one of claims 1 - 4, characterized in that the copolymer is derived from ethylene and vinyl derivatives of either silicones or phosphorus compounds, preferably diethoxyvinylsilane or diethylvinylphosphonate. 14. Composition according to any one of claims 1-4, characterized in that the copolymer is derived from ethylene and an ethylenically unsaturated hydroxy compound, preferably allyl alcohol. 15. Composition according to any one of claims 1 - 4> characterized in that the copolymer is derived from ethylene and an ethylenically unsaturated amine or nitrile, preferably allylamine or allyl cyanide. 16. Composition according to any one of claims 1-4, characterized in that the copolymer is derived from (1) ethylene, (2) either acrylic acid or methacrylic acid or their metal salts, amides or nitriles, and (3) vinyl acetate. 17. Composition according to any one of claims 1-4, characterized in that the copolymer is derived from (1) ethylene, (2) a vinyl halide and (3) either vinyl methyl ether or acrylic acid. 18. Composition according to any of claims 1-4, characterized in that the copolymer is derived from (l) ethylene, (2) N-vinyl pyrrolidone and (3) either methyl vinyl ketone or vinyl methyl ether. 19. Composition according to claim 1, characterized in that the third comonomer is either a vinyl or an allyl ester of a C 1 - to C 2 -monocarboxylic acid, preferably vinyl acetate. 20. Composition according to any of the aforementioned claims, characterized in that the copolymer has an average molecular weight of between 1,000 and 60,000 as this can be measured by vapor phase osometry. 21. Composition according to claim 20, characterized in that the copolymer has an average molecular weight of over 3000, preferably over 3500. 22. Composition according to claim 21, characterized in that the copolymer has an average molecular weight of between 4,000 and 20,000. 23. Composition according to any of the aforementioned claims, characterized in that the substituted ethylene contains between 3 and 40 carbon atoms per molecule. 24. Composition according to any one of the aforementioned claims, characterized in that the copolymer contains from 86 to 97 mole percent ethylene. 25. Composition according to any one of the aforementioned claims, characterized in that the proportion of the copolymer varies from 0.0001 and 10 percent by weight based on the weight of the residual fuel, the flash distillate, the crude oil or the shale oil.