EP0071513B1 - Additives for use as pour point dispersants for middle distillate hydrocarbons, and compositions of middle distillate hydrocarbons containing said additives - Google Patents

Description

The invention relates to middle hydrocarbon distillates (fuel oils, gas oils), the cloud point of which is lowered by adding nitrogen additives.

The petroleum distillates concerned by the invention consist of middle distillates (fuel oils, gas oils) whose distillation range (standard ASTM D 86-67) is between 150 ° C and 450 ° C. The diesel oils considered more particularly have a distillation interval ranging from an initial temperature between 160 ° C and 190 ° C to a final temperature between 350 ° C and 390 ° C.

• -les polymères à base d'oléfines à longue chaîne.
• -les copolymères à base d'alpha-oléfines,
• -les copolymères éthylène-acétate de vinyle,
• -les N-acylaminoéthylesters de polymères contenant des acides, ou encore:
• -des composés halocarbonés.

There are a large number of products on the market recommended to improve the limit filterability temperature and the pour point of petroleum fractions rich in paraffins, such as for example:

• -polymers based on long chain olefins.
• -alpha-olefin-based copolymers,
• - ethylene-vinyl acetate copolymers,
• -N-acylaminoethyl esters of polymers containing acids, or also:
• - halocarbon compounds.

These products act on kinetic phenomena of crystallization and modify the size of the crystals, allowing the use of the suspension at a lower temperature without clogging of the pipes and filters. The products mentioned above do not modify the temperature at which the first paraffin crystals appear. In fact, it has hitherto been considered that this temperature is a given depending on the molecular weight and the formula of the paraffins and on the nature of the solvent.

Lowering the cloud point of middle distillates (especially diesel) by an additive, would be of great interest to refiners, because it would allow, without modifying the distillation scheme, to comply with the specifications, which are currently evolving in the direction of 'greater severity.

Additives similar to those considered in the present application and defined below have been described in the prior art. It is indicated below how the invention differs from the teaching of the closest prior documents.

US Pat. No. 3,035,907 describes additives which can be used in particular in fuel oils and diesel fuels and which are obtained by amidation of itaconic acid with a primary or secondary mono or diamine. Itaconic acid (or methylene succinic) is not one of the alkenyl succinic acids which will be considered in the present application, and whose alkenyl radicals containing from 10 to 30 carbon atoms.

Furthermore, in this prior document, the formation of amides is stopped, whereas, taking into account the operating conditions used in the preparation of the additives used in the invention, these contain a substantial proportion of imide functions.

US Patent 3,046,102 describes additives for fuel oils consisting in particular of amino acids formed between itaconic acid and an aliphatic amine, primary or secondary. The reaction is an amidation. In addition, as for the previous document, itaconic acid is not one of the alkenyl succinic acids considered in the invention.

US Patent 2,982,630 describes a gasoline additive consisting of an alkenyl succinamic N-ethanol acid obtained by reaction of equimolar proportions of alkenyl succinic acid anhydride and ethanolamine. The reaction is carried out under conditions such that no water of condensation is formed. Therefore, no imide groups are formed. In a different manner, in the present application, volatile products (water) are eliminated, with the formation of imide groups. In addition, the additives are used in middle distillates (gas oils, fuel oils) and not in gasolines.

Patent FR 1,197,418 describes additives used in particular in fuel oils (fuel oils) and consisting in particular of amide acids such as succinamic acids and maleamic acids. It is mentioned that the formation of cyclic imides is avoided (page 3, column 1, lines 25-27).

We have now discovered that certain chemical compounds, a definition of which is given below, have, when added to middle distillates, the property of allowing the first paraffin crystals to appear only at a temperature lower than that at which these crystals would appear in the absence of such additives. This property is all the more unexpected since it is preserved after several heating and cooling cycles and manifests itself by a mechanism which has not yet been explained.

This class of chemical compounds also has an effect on other properties of middle distillates (in particular gas oils), by modifying the behavior of the medium which contains the precipitated paraffins.

Thus, the compounds recommended in the invention have a significant action on the limit filterability temperature and the flow temperature.

When the paraffin crystals whose formation is caused by cooling have appeared, their natural tendency is to collect by gravity in the lower part. This phenomenon, generally known in the term of sedimentation, causes clogging of the pipes and filters and is detrimental to the proper use of middle distillates and in particular diesel. Compounds chemicals recommended in the invention can significantly reduce the rate of sedimentation of paraffins formed by cooling gas oils and other middle distillates.

Finally, the products recommended for their properties mentioned above also confer on the gas oils and middle distillates to which they are added, anti-corrosion properties on metal surfaces.

où R représente un radical aliphatique saturé monovalent de 1 à 30 atomes de carbone, Z est choisi parmi les groupements -NR'- dans lesquels R' représente un atome d'hydrogène ou un radical aliphatique saturé monovalent de 1 à 30 atomes de carbone, n est un nombre entier de 2 à 4, m est zéro ou un nombre entier de 1 à 4; et R⁵ représente un radical aliphatique saturé divalent de 1 à 18 atomes de carbone; ledit composé à fonction amine primaire étant utilisé en une proportion de 0,9 à 1,2 mole par mole dudit composé dicarboxylique et ladite réaction étant effectuée à une température de 120 à 200°C, pendant un temps suffisant pour former la quantité théorique de produits volatils consistant en eau et/ou en alcool, qui sont éliminés.Generally, the middle petroleum distillate compositions of the invention may be. defined as comprising a major proportion of middle petroleum distillate and a minor proposal, sufficient to lower the cloud point thereof, of an additive consisting of a product of average molecular weight of approximately 300 to 10,000 resulting from the reaction of at least one aliphatic dicarboxylic compound chosen from maleic and alkylmaleic anhydrides, alkenylsuccinic anhydrides having from 10 to 30 carbon atoms in the alkenyl radical, dicarboxylic acids and corresponding light alkyl diesters, and at least one compound having a function primary amine corresponding to one of the general formulas:

where R represents a monovalent saturated aliphatic radical of 1 to 30 carbon atoms, Z is chosen from the groups -NR'- in which R 'represents a hydrogen atom or a monovalent saturated aliphatic radical of 1 to 30 carbon atoms, n is an integer from 2 to 4, m is zero or an integer from 1 to 4; and R ⁵ represents a divalent saturated aliphatic radical of 1 to 18 carbon atoms; said compound with primary amine function being used in a proportion of 0.9 to 1.2 mole per mole of said dicarboxylic compound and said reaction being carried out at a temperature of 120 to 200 ° C, for a time sufficient to form the theoretical amount of volatile products consisting of water and / or alcohol, which are eliminated.

The compounds of formula (I) below can consist of primary amines of formula R ^I- NH _P (in this case, in formula (I), Z represents the group -NH-, and the value of m is zero ).

Preferably, the radical R ¹ is linear and contains from 12 to 30, and more particularly from 16 to 25 carbon atoms. As specific examples of these amines, mention may be made of: dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosylamine and docosylamine. Hexadecylamine and octadecylamine being preferred.

qui correspond à la formule générale (1) dans laquelle Z représente le groupement -NH-; m peut avoir une valeur de 1 à 4 et n une valeur de 2 à 4, de préférence 3.The compounds of formula (I) can also consist of polyamines derived from saturated aliphatic amines corresponding to the formula:

which corresponds to the general formula (1) in which Z represents the group -NH-; m can have a value of 1 to 4 and n a value of 2 to 4, preferably 3.

Preferably, the radical R ¹ is linear and contains from 12 to 30 and more particularly from 16 to 25 carbon atoms.

As specific compounds, there may be mentioned: N-dodecyl diamino-1,3 propane, N-tetradecyl diamino-1,3 propane, N-hexadecyl diamino-1,3 propane, N-octadecyl diamino-1,3 propane, N-eicosyl diamino-1,3 propane, N-docosyl diamino-1,3 propane, N-hexadecyldipropylene triamine, N-octadecyl dipropylene triamine, N-eicosyldipropylene triamine and N-docosyldipropylene triamine. Most advantageously, N-docosyl-, N-eicosyl-, N-octadecyl-, N-hexadecyl- or N-dodecyl-diamino 1,3 propane, as well as N-hexadecyl- and N-octadecyl are used. - dipropylene-triamine.

où R² et R³, identiques ou différents, sont chacun un radical alkyle ayant de 1 à 24 et de préférence de 8 à 24 atomes de carbone, R² et R³ renfermant à eux deux de préférence de 16 à 32 atomes de carbone; n a une valeur de 2 à 4 et m une valeur de 1 à 4.The compounds of formula (I) can also consist of polyamines corresponding to the formula:

where R ² and R ³ , identical or different, are each an alkyl radical having from 1 to 24 and preferably from 8 to 24 carbon atoms, R ² and R ³ containing together the two preferably from 16 to 32 carbon atoms ; n has a value of 2 to 4 and m a value of 1 to 4.

As specific compounds, mention may be made of N, N-diethyl-diamino-1,2 ethane, N, N-diisopropyldiamino-1,2 ethane, N, N-dibutyl-diamino-1,2 ethane, N, N-diethyl-diamino-1,4-butane, N, N-dimethyl-diamino-1,3 propane, N, N-diethyl-diamino-1,3 propane, N, N-dioctyl-diamino-1, 3 propane, N, N-didécyldiamino-1,3 propane, N, N didodécyl-diamino-1,3 propane, N, N-ditétradécyl-1,3-propane, N, N-dihexadécyldiamino-1 , 3 propane, N, N-dioctadecyldiamino-1,3 propane, N, N-didodecyldipropylenetriamine, N, N-ditetradecyldipropylene triamine, N, N-dihexadecyldipropylene triamine and N, N-dioctadecyldipropylenetriamine.

où R⁵ représente un radical aliphatique saturé divalent, linéaire ou ramifié, de préférence linéaire, renfermant de 1 à 18 et de préférence de 10 à 18 atomes de carbone. Comme exemples spécifiques, on peut citer:

• la monoéthanolamine, l'amino-1 propanol-3, 1'amino-1 butanol-4, l'amino-1 pentanol-5, l'amino-1 hexanol-6, l'amino-1 heptanol-7, l'amino-1 octanol-8, l'amino-1 décanol-10, l'amino-1 undécanol-11, l'amino-1 tridécanol-13, l'amino-1 tétradécanol-14, l'amino-1 hexadécanol-16, l'amino-2 méthyl-2 propanol-1, l'amino-2 butanol-1 et l'amino-2 pentanol-1

The compound with primary amine function involved in the preparation of the additives of the invention can also consist of an amino alcohol of formula (II):

where R ⁵ represents a divalent saturated aliphatic radical, linear or branched, preferably linear, containing from 1 to 18 and preferably from 10 to 18 carbon atoms. As specific examples, we can cite:

• monoethanolamine, amino-1 propanol-3, amino-1 butanol-4, amino-1 pentanol-5, amino-1 hexanol-6, amino-1 heptanol-7, amino-1 octanol-8, amino-1 decanol-10, amino-1 undecanol-11, amino-1 tridecanol-13, amino-1 tetradecanol-14, amino-1 hexadecanol- 16, 2-amino-2-methyl-propanol-1, 2-amino butanol-1 and 2-amino pentanol-1

It should be understood that, without departing from the scope of the invention, it is possible to bring into play one or more compounds corresponding to formula (I) and / or one or more compounds corresponding to formula (II).

The dicarboxylic compounds on which the condensation of a compound of formula (I) or of a compound of formula (II) as described above is carried out, are more particularly chosen from maleic anhydride, alkylmaleic anhydrides, for example l 'methylmaleic (or citraconic) anhydride or also among alkenyl succinic anhydrides, for example those obtained by the action of at least one olefin-a preferably linear (having 10 to 30 carbon atoms) on maleic anhydride. Mention may be made more specifically of n-octadecenyl succinic anhydride or dodecenyl succinic anhydride. It is of course possible to use mixtures of two (or more) of these compounds.

Instead of the anhydrides mentioned above, it is possible to use the corresponding dicarboxylic acids, as well as the light alkyl diesters thereof (such as, for example, methyl, ethyl, propyl and butyl esters) .

The primary amine-functional compounds of formulas (I) and (II) are usually used in an amount of 1.02 to 1.2 moles, preferably 1.05 to 1.1 moles, per mole of dicarboxylic compound. It is also possible to bring into play a slight defect in the compound with a primary amine function (I) or (II), up to 0.9 mole per mole of dicarboxylic compound. The proportion is therefore from 0.9 to 1.2 moles / mole, as indicated above.

The condensation of the compounds of formula (I) and / or (II), on the dicarboxylic compounds (for example dicarboxylic acids, esters, or preferably anhydrides) can be carried out without solvent, but preferably a solvent consisting more particularly of an aromatic or naphtheno-aromatic hydrocarbon with a boiling point of between 70 ° and 250 ° C for example: toluene, xylenes, diisopropylbenzene or even an petroleum fraction having the appropriate distillation range.

In order to prepare the additive compositions considered in the invention, it is possible in practice to proceed as follows: In a reactor containing the dicarboxylic compound, and maintaining the temperature between 30 ° C. and 80 ° C., little is introduced at little the compound of formula (I) and / or (II). The temperature is then raised to 120 ° C-200 ° C by eliminating the volatile products formed (water or alcohols), either by entrainment with a stream of inert gas, or by azeotropic distillation with the chosen solvent; the dry matter concentration is for example 40 to 70%., most often close to 60%.

The reaction time, after addition of the reagents, is for example between 1 and 8 hours and preferably between 3 and 6 hours.

The additives considered in the invention are particularly advantageous for improving the cloud point of petroleum middle distillates (in particular gas oils), that is to say to reduce the temperature of appearance of the first crystals of n-paraffins contained in those -this.

Although the mechanism of action of these additives on the temperature of appearance of paraffin crystals in middle distillates has not yet been clearly elucidated, there is a marked improvement in the cloud point of the middle distillates treated with these additives, when added at concentrations ranging, for example, from 20 to 2000 g per tonne of middle distillate. Preferred concentrations range from 100 to 2000 g / t. The lowering of the cloud point can go for example up to 5 ° C, sometimes more.

In addition, it is remarkable to note that the additives considered in the invention which are effective in improving the cloud point of middle distillates have, on the other hand, the property of inhibiting the sedimentation of n-paraffins in middle distillates. at rest, to improve the limit filterability temperature and the flow temperature and to inhibit corrosion of the metal surfaces in contact with these distillates.

Thus, in the concentration range of the additive, from 20 g to 2000 g per tonne, it is possible to observe a lowering of the filterability temperature which can go for example up to 12 ° C., a lowering of the point of 'flow of up to 20 ° C, a decrease in the proportion of sedimented paraffins and a clear anticorrosion effect observed in particular on ferrous metals.

To formulate the middle distillate compositions of the invention, it is possible to add the additives directly to the middle distillate by a simple mixing operation.

It is however often advantageous to introduce them in the form of "stock solutions" prepared beforehand in the solvents already mentioned above.

The "mother solutions" can contain, for example, from 20 to 60% by weight of additives.

The following examples illustrate the invention and should in no way be taken as limiting.

Example 1

2.700 g of a commercial polyamine (containing a mixture, approximately 27% of palmityl 1,3-propane-diamine and 70% of stearyl 1,3 propanediamine having an equivalent) are introduced into a 20 I reactor fitted with good stirring. 370 g for a primary amine) and 2,700 g of xylene, the amine is dissolved at 50 ° C and then cooled to 30 ° C, a solution of 699 g of maleic anhydride dissolved in 1,050 g of xylene is added. maintaining the interior temperature at 40 ° C; the addition lasts one hour, then heated for 3 hours at xylene reflux, the internal temperature is 144 ° C., 157 g of water are removed by distillation corresponding to 128 g of reaction water and 29 g of water contained in the amine; at the end of the reaction, 500 g of xylene are distilled to obtain a 50% by weight solution of the additive I in xylene.

Additive 1 was analyzed after evaporation of the solvent. Its number molecular mass, measured by tonometry, is 1800. The infrared spectrum in thin layer shows the existence of imide bands at 1700 and 1780 cm- ¹ secondary amide at 1635 and 1560 cm- ¹ and secondary amine at 3300 cm- ¹ .

Additives II to VII have the same bands as Additive I. Their molecular weights are between 1500 and 3000.

L'effet de l'additif I sur l'abaissement du point de trouble de chacune des deux coupes de gazole, en fonction de la concentration en additif, déterminé suivant la méthode NF T 60 105, est montré au tableau Il ci-après.

The activity of this additive I is tested in two cuts of diesel fuel of Aramco origin, the characteristics of which are indicated in Table I below.

The effect of the additive I on the lowering of the cloud point of each of the two cuts of diesel, as a function of the concentration of additive, determined according to the NF T 60 105 method, is shown in Table II below.

Example 2

• Additif I : produit utilisé dans l'exemple 1
• Additif Il : produit de la condensation sur l'anhydride maléique de la N-stéaryl-dipropylène triamine;
• Additif III : produit de la condensation sur l'anhydride maléique de la stéaryl-amine.

In this example, 0.1% by weight is used in the two gas oil fractions used in Example 1, additives which differ mainly in the nature of the starting amine, the method of preparation being the same as in Example 1.

• Additive I: product used in Example 1
• Additive II: produces condensation on the maleic anhydride of N-stearyl-dipropylene triamine;
• Additive III: produces condensation on the maleic anhydride of stearylamine.

The results are shown in Table III below.

It is found that the effect of lowering the cloud point is most important in the case of additive I, in which the starting amide is a mixture of two N-alkyl 1,3 propane diamines.

Example 3

• Ainsi on utilise:
  • Additif I : produit utilisé dans l'exemple 1
  • Additif IV : produit de la condensation sur l'anhydride maléique de la N-béhényl 1,3 propane diamine (béhényl=C₂₂)
  • Additif V : produit de la condensation sur l'anhydride maléique de la N-lauryl, 3 propane diamine (lauryl=C₁₂)

In this example, 0.1% by weight is used in the same two gas oils as above, of additives which differ essentially by the length of the alkyl chain of the starting amine:

• So we use:
  • Additive I: product used in Example 1
  • Additive IV: product of condensation on the maleic anhydride of N-behenyl 1,3 propane diamine (behenyl = C ₂₂ )
  • Additive V: product of condensation on the maleic anhydride of N-lauryl, 3 propane diamine (lauryl = C ₁₂ )

The results of the cloud point determinations are shown in Table IV below.

It is noted that the additive derived from a diamine with an alkyl chain of 12 carbon atoms is clearly less effective than those which derive from a diamine with a longer alkyl chain: 16, 18 or 22 carbon atoms.

Example 4

In this example, additives are used, at a rate of 0.1% by weight in the same two gas oils as above, which differ essentially from each other in the nature of the starting dicarboxylic compound.

• Additif 1 : produit utilisé dans l'exemple 1, dérivant de l'anhydride maléique
• Additif VI : produit de la condensation de la N-stéaryl 1,3 propane diamine sur l'anhydride méthylmaléique (citraconique)
• Additif VII : produit de la condensation de la N-stéaryl 1,3 propane diamine sur l'anhydride n-octadécenyl succinique.

So we use:

• Additive 1: product used in Example 1, derived from maleic anhydride
• Additive VI: product of the condensation of N-stearyl 1,3 propane diamine on methylmaleic anhydride (citraconic)
• Additive VII: product of the condensation of N-stearyl 1,3 propane diamine on n-octadecenyl succinic anhydride.

The cloud points determined are indicated in Table V below:

Example 5

In this example, the inhibitory action of an additive according to the invention was tested on the sedimentation of n-paraffins crystallizing in a fraction of diesel fuel kept at rest at low temperature.

The additive used is the additive already used previously.

Two 100 cm3 test tubes are filled with a diesel cut characterized by the distillation interval PI = 186 ° C, PF = 385 ° C- (diesel n ° 2 already used previously).

In the first test tube, no additive is introduced.

In the second test tube, 0.1% by weight of the additive I is introduced.

The two test pieces are hermetically sealed, then left to stand in a cold room at -10 ° C for one week.

After a week, the degree of sedimentation of the precipitated paraffins, expressed by the volume of the clear upper phase, is noted in the following table:

All of the precipitated paraffins are therefore found in 50% of the volume in the non-additive diesel, which makes the lower part more difficult to use by clogging the pumps, filters and pipes.

For the additive diesel, there is only 15% of clear upper phase. Paraffins are in 85% of the total volume. They are better dispersed and easier to transport.

Example 6

In this example, the effect of an additive according to the invention is tested on the limit filterability temperature (TLF) of the two diesel fuel cuts already described above.

The TLFs are determined according to standard NF M 07-042

Example ₇

In this example, the anti-corrosion effect of the additive I of example 1 is tested.

Product 1 was used in the two gas oils No. 1 and No. 2 already described above, at a concentration of 0.01% by weight.

• La température est de 32,2°C et la durée: 20 heures

The corrosion test consists in studying corrosion by synthetic sea water, of cylindrical steel or polished iron specimens according to standard ASTM D 665 modified as follows:

• The temperature is 32.2 ° C and the duration: 20 hours

The two non-additive diesel no. 1 and no. 2 give rusty test pieces at 100% of their surface and the two gas oils containing 0.01% by weight of additive give intact test pieces with 0% rust.

Example 8

In this example, the effect of the additive 1 according to the invention is tested on the point of flow of diesel cuts. Pour points are determined according to French standard NFT 60105; the additive is tested at 0.1% by weight. The results are shown in Table VIII below.

Example 9

A solution consisting of 294 g (3 moles) of maleic anhydride dissolved in 500 g of xylene is introduced into a 3 I reactor, fitted with a Dean and Stark water separation system and good stirring. . Maintaining the temperature of this solution between 30 and 40 ° C, there is added, in 1.5 h, a solution obtained from 1230 g (3 moles) of N, N-didodecyldiamino 1.3 propane and 1000 g xylene. The whole is heated for 3 hours at the reflux of xylene, time during which 55 g of water are collected evacuated from the reaction medium. The reaction product constitutes additive VIII which is in solution in xylene at a concentration very close to 50% by weight.

Example 10.

Following a procedure identical to that of Example 9, the condensation of 532 g (2 moles) of dodecenylsuccinic anhydride is carried out on 820 g (2 moles) of N, N-didodecyldiamino-1,3 propane. The condensation product constitutes additive IX, the concentration of which in xylene is adjusted to obtain a value of 50% by weight.

The effect of the additives VIII and IX thus obtained was tested on the cloud point (determined according to standard NF T 60-105), the filterability limit temperature (determined according to standard NF M 07-042) and the point d flow (determined according to standard NF T 60-105) of the two gas oils n ° 1 and n ° 2, the concentration of the additives being, in each case, of 0.1% by weight.

The results are collated in Table IX below.

Example 11

294 g (3 moles) of maleic anhydride dissolved in 500 g of xylene are introduced into a reactor of 3 with good stirring and the mixture is cooled to 30 ° C. A solution in 324 g of xylene of a mixture of 55 mol% of ethanolamine and 45 mol% of a commercial cut of N-alkyl propylenediamines is added, the alkyl chains of which consist of approximately 27% of C chain ₁₆ and 72% of chain in C _'8 (equivalent molecular mass: 370 for a primary amine function), the overall amount of primary amine equivalents being 3, I, the temperature being kept below 40 ° C.

The addition lasts one hour, then heated for 3 hours at reflux of xylene. The indoor temperature is 144 ° C. 67 g of water are removed by distillation, corresponding to 54 g of reaction water and 13 g of water contained in the amine; at the end of the reaction, diluted with 200 g of xylene to obtain a 50% by weight solution of the additive X in xylene.

Additive X was analyzed after evaporation of the solvent. The thin layer infrared spectrum shows the existence of imide bands at 1700 and 1780 cm- '.

Example 12

This example is carried out according to the procedure described in Example 11, while maintaining molar ratios between the reactants identical to that given in Example 11.

Ethanolamine is condensed on alkenyl succinic anhydride obtained by reaction, in equimolecular amounts, of maleic anhydride on a section of linear olefins-a, containing approximately 49% of C ₂₀ olefin, 42% of C ₂₂ and 9% C ₂₄ . A molar ratio of 1/1 is used between ethanolamine and the anhydride groups of alkenyl succinic anhydride. The result of this condensation provides the additive XI.

This additive is obtained in solution in xylene, the amount of which is adjusted so as to obtain a 50% by weight solution in xylene.

The activity of the additive compositions prepared in Examples 11 and 12 is tested by incorporating them in an amount of 0.1% by weight of additive relative to the diesel fuel, into the two cuts of diesel oils of ARAMCO origin, designated by G , and G ₂ , the characteristics of which have been indicated above.

• -le point de trouble suivant la méthode NF T 60-105
• -la température limite de filtrabilité (TLF) par la méthode NF M 07-042
• -le point d'écoulement par la méthode NF T 60-105.

For each of the compositions thus formed, three determinations were made:

• -the cloud point according to the NF T 60-105 method
• -the filterability limit temperature (TLF) by the NF M 07-042 method
• -the pour point by the NF T 60-105 method.

The results of these determinations are collated in Table X below:

Claims (12)

1. Oil middle distillate composition, characterized as comprising a major proportion of oil middle distillate and a minor proportion, sufficient to decrease the cloud point of said distillate, of an additive consisting of a material having an average molecular weight of about 300 to 10,000 and resulting from the reaction of at least one aliphatic dicarboxylic compound selected from the maleic and alkylmaleic anhydrides, the alkenylsuccinic anhydrides having 10 to 30 carbon atoms in the alkenyl radical, the corresponding dicarboxylic acids and lower alkyl diesters, with at least one compound having a primary amine function, complying with one of the general formulas:

and

wherein R represents a monovalent saturated aliphatic radical of 1 to 30 carbon atoms, Z is selected form the-NR'-groups, wherein R' is a hydrogen atom or a monovalent saturated aliphatic radical containing 1 to 30 carbon atoms, n is an integer from 2 to 4, m is zero or an integer from 1 to 4; and R⁵ represents a divalent saturated aliphatic radical having 1 to 18 carbon atoms; said compound having a primary amine function being used in a proportion of 0.9 to 1.2 mole per mole of said dicarboxylic compound and said reaction being effected at a temperature of 120 to 200°C for a sufficient time to form the theoretical amount of volatile products consisting of water and/or alcohol, which are eliminated.

2. A composition according to claim 1, characterized in that said compound having a primary amine function (I) consists of at least one mono-amine of the formula R^I NH₂ where R' represents a linear alkyl radical of 12 to 30 carbon atoms.

3. A composition according to claim 1, characterized in that said compound having a primary amine function (1) consists of a least one polyamine of the formula

wherein R¹ represents a linear alkyl radical with 12 to 30 carbon atoms, n is an integer from 2 to 4 and m an integer from 1 to 4.

4. A composition according to claim 1, characterized in that said compund having a primary amine function (I) consists of at least one polyamine of the formula

wherein R² and R³ are each a linear alkyl radical of 8 to 24 carbon atoms, R² and R³ together comprising from 16 to 32 carbon atoms, n is an integer from 2 to 4 and m is an integer from 1 to 4.

5. A composition according to claim 1, characterized in that said compound having a primary amine function (II) consists of at least one amino-alcohol of the formula:

where R⁵ represents a linear alkylene radical of 1 to 18 carbon atoms.

6. A composition according to one of claims 1 to 5, characterized in that said aliphatic dicarboxylic compound is selected from maleic anhydride, methylmateic anhydride and the n-octadecenyl and dodecenyl succinic anhydrides.

7. A composition according to one of claims 1 to 6, characterized in that said reaction is performed in a hydrocarbon solvent having a boiling point between 70 and 250°C.

8. A composition according to one of claims 1 to 7, characterized in that said reaction comprises admixing, at a temperature of 30 to 80°C, said dicarboxylic compound with said compound of formula (I) or (II) and heating the resultant mixture at a temperature of 120 to 200°C for 1 to 8 hours.

9. A composition, characterized in that said middle distillate has a distillation range between 150 and 450°C.

10. A composition according to claim 9, characterized in that said middle distillate consists of a gas oil cut having a distillation range from an initial temperature of 160 to 190°C to a final temperature of 350 to 390°C.

11. A composition according to one of claims 1 to 10, characterized in that the proportion of said additive is from 20 to 2000 g/ton.

12. A composition according to claim 11, characterized in that the proportion of said additive is about 1000 g/ton.