Use Of Compounds Revealing The Efficiency Of Filterability Additives In Hydrocarbon Distillates, And Synergic Composition Containing Same

Abstract

The invention relates to the use, in a hydrocarbon distillate with a boiling temperature of between 150 and 450 C. and a crystallization onset temperature as measured by Differential Calorimetric Analysis of greater than or equal to 50 C., preferably of 5 C. to +10 C., of a homopolymer obtained from an olefinic ester of carboxylic acid of 3 to 12 carbon atoms and from a fatty alcohol containing a chain of more than 16 carbon atoms and optionally an olefinic double bond, as a compound for revealing the efficiency of filterability additives based on copolymer and/or terpolymers of ethylene and of vinyl ester of a carboxylic acid of 3 to 12 carbon atoms, and of a monoalcohol containing 1 to 10 carbon atoms. The invention is also directed to an additive composition comprising a conventional hydrocarbon filterability additive in combination with an efficiency reveal additive, and also to the combustion fuels, motor fuel and oil fuel that comprise these additive combinations.

Claims

1. A method of improving the activity of filterability additives, added to a hydrocarbon distillate, the method comprising: adding a polyacrylate to a hydrocarbon distillate containing filterability additives, the filterability additives comprising a copolymer and/or terpolymer of ethylene and of a vinyl ester of a carboxylic acid with 2 to 5 carbon atoms and of a monoalcohol comprising 1 to 10 carbon atoms, the hydrocarbon distillate being resistant to the filterability additives, wherein the polyacrylate comprises side hydrocarbon chains with 18-40 carbon atoms, and the hydrocarbon distillate has a boiling temperature comprised between 150 and 450 C., an onset crystallization temperature as measured by differential scanning calorimetry analysis, greater than or equal to 5 C., and a weight content of n-paraffins containing more than 18 carbon atoms greater than 4%, wherein the polyacrylate cooperates synergistically with the filterability additives to increase the filterability of the hydrocarbon distillate, and wherein the polyacrylate is not a polymethacrylate.

2. The method according to claim 1, wherein the hydrocarbon distillate comprises a weight content greater than or equal to 0.7% of n-paraffins, the carbon number of which is greater than 24.

3. The method according to claim 1, wherein the distillate comprises a mixture of 0.7 to 2% by weight of n-paraffins having a carbon number ranging from C.sub.24 to C.sub.40.

4. The method according to claim 1, wherein the filterability additives are copolymers of ethylene containing more than 20% of ester units.

5. The method according to claim 1, wherein the filterability additives are selected from copolymers of ethylene and of vinyl acetate, of ethylene and vinyl propionate, of ethylene and vinyl versatate, of ethylene and (alkyl)acrylates, of ethylene and (alkyl)methacrylates, taken alone or as a mixture, comprising from 20 to 40% by weight of ester units.

6. The method according to claim 1, wherein said esters are of the vinyl acetate, vinyl propionate, vinyl versatate, (alkyl)acrylate and (alkyl)methacrylate type, the alkyl group containing 1 to 7 carbon atoms.

7. The method according to claim 1, wherein the homopolymer is obtained by polymerization of an olefinic ester of acrylic acid, and of an alcohol comprising from 18 to 50 carbon atoms.

8. The method according to claim 1, wherein the distillate is selected from the distillates with a boiling temperature comprised between 150 and 450 C. comprising the distillates from direct distillation, in vacuo distillates, hydrotreated distillates, distillates stemming from catalytic cracking and/or hydrocracking of distillates in vacuo, distillates resulting from ARDS type conversion and/or viscosity breaking methods, distillates stemming from valuation of Fisher Tropsch cuts, and distillates resulting from BTL conversion of vegetable and/or animal biomass, and distillates containing alkyl esters of vegetable or animal oils, taken alone or as a mixture.

9. The method according to claim 1, wherein the polyacrylate has an average molecular weight Mw comprised between 10,000 and 19,000.

10. The method according to claim 1, wherein the hydrocarbon distillate has an onset crystalization temperature as measured by differential scanning calorimetry analysis, greater than or equal to 1.2 C.

11. A method of improving the activity of filterability additives, added to a hydrocarbon distillate, the method comprising: adding a polyacrylate to a hydrocarbon distillate containing filterability additives, the filterability additives being ethylene copolymers comprising from 20 to 40% by weight of ester units and selected from the group consisting of copolymers of ethylene and of vinyl acetate, copolymers of ethylene and vinyl propionate, copolymers of ethylene and vinyl versatate, copolymers of ethylene and (alkyl)acrylates, copolymers of ethylene and (alkyl)methacrylates, and mixtures thereof, the hydrocarbon distillate being resistant to the filterability additives, wherein the polyacrylate comprises side hydrocarbon chains with 18-40 carbon atoms, and the hydrocarbon distillate has a boiling temperature comprised between 150 and 450 C., an onset crystallization temperature as measured by differential scanning calorimetry analysis, greater than or equal to 5 C., and a weight content of n-paraffins containing more than 18 carbon atoms greater than 4%, wherein the polyacrylate cooperates synergistically with the filterability additives to increase the filterability of the hydrocarbon distillate, and wherein the polyacrylate is not a polymethacrylate.

12. A method of improving the activity of filterability additives, added to a hydrocarbon distillate, the method comprising: adding a polyacrylate to a hydrocarbon distillate containing filterability additives, the filterability additives comprising a copolymer and/or terpolymer of ethylene and of a vinyl ester of a carboxylic acid with 2 to 5 carbon atoms and of a monoalcohol comprising 1 to 10 carbon atoms, the hydrocarbon distillate being resistant to the filterability additives, wherein the polyacrylate cooperates synergistically with the filterability additives to increase the filterability of the hydrocarbon distillate, wherein the polyacrylate is not a polymethacrylate.

13. The method according to claim 12, wherein the polyacrylate comprises side hydrocarbon chains with 18-40 carbon atoms, and the hydrocarbon distillate has a boiling temperature comprised between 150 and 450 C., an onset crystallization temperature as measured by differential scanning calorimetry analysis, greater than or equal to 5 C., and a weight content of n-paraffins containing more than 18 carbon atoms greater than 4%.

14. The method according to claim 12, wherein the filterability additives are selected from copolymers of ethylene and of vinyl acetate, of ethylene and vinyl propionate, of ethylene and vinyl versatate, of ethylene and (alkyl)acrylates, of ethylene and (alkyl)methacrylates, taken alone or as a mixture, comprising from 20 to 40% by weight of ester units.

Description

DETAILED DESCRIPTION

[0030] With the purpose of illustrating the advantages of the present invention, examples are given as non-limiting examples.

Example 1

[0031] This example describes the nature of the components of the invention and comparative compounds. The distillates according to the invention resistant to filterability or LFT (CFPP) additives alone are called Fi and the distillates non-resistant to these additives are called Gi. They are described in the Table I hereafter.

TABLE-US-00001 TABLE I G1 G2 F1 F2 F3 % of normal paraffins* <C.sub.13 4.53 2.86 2.05 1.77 0.41 C.sub.13-C.sub.17 8.61 7.44 4.58 4.2 4.26 C.sub.18-C.sub.23 5.47 4.02 4.64 4.31 9.38 >C.sub.24 0.66 0.24 0.94 0.8 1.5 Total of 19.27 14.56 12.21 11.08 15.56 n-paraffins LFT ( C.) 4 8 1 0 7 FT ( C.) 12 15 6 6 CPT ( C.) 4 7 2 0 7 Density 0.8327 0.8414 0.8541 0.863 0.870 Sulfur in ppm 39.8 320 930 1240 1950 Viscosity at 2.725 2.752 2.6348 40 C. mm.sup.2/s Cetane as calculated 50.1 50.2 44.8 according to ASTM D4737 IP391 aromatic content Monoaromatics % 22.7 23 26.6 27.6 Diaromatics in % 6.2 5.5 9.1 8.2 Polyaromatics in % 0.6 1.2 1.9 3.3 TCC ( C.) 7/6.2 8.3 1.2 1.2 5 D86 distillation ( C.) Initial point 167.6 176.8 156.4 162.6 164.1 T10 203 207.6 189.8 195.5 T20 224.7 225.6 203.5 220.7 T50 274.5 270.7 271.9 293.6 T80 317.1 314.1 331.3 341 T90 337.4 333.2 354.3 357 360 T95 353.9 345.9 371.1 372 Final point 356 352.2 373.4 382.8 *% by weight of paraffins determined by liquid chromatography/gas chromatography coupling FT = Flow temperature LFT = Filterability temperature CPT = Cloud point temperature as measured by ASTM D2500 or EN 23015 TCC = Onset crystallization temperature as measured by Differential Scanning Calorimetry Analysis (ACD or DSC) or according to IF 389-93.

[0032] The FT temperature or flow point measured for distillates used as fuels is the lowest temperature at which the hydrocarbon is still able to flow. The CPT or cloud point temperature is a visual appreciation of the germination and crystallization of paraffins, this measurement is less accurate than that of the onset crystallization temperature Tcc. The LFT, the limiting filterability temperature of crystals of paraffins precipitating in hydrocarbons at low temperature, is intermediate between both of these extreme temperatures FT and Tcc: it is intended for appreciating the temperature at which the size of the crystals is still sufficiently small for not blocking the filters.

[0033] Generally, the respective variations of LFT, FT and Tcc are not necessarily related to each other and are more often dependent on the chemical composition of the products. Examples of distillates F1, F2, F3 according to the invention have an n-paraffin content greater than or equal to 0.7% and a Tcc>5 C., while distillates G1, G2 have an n-paraffin content less than 0.7% and Tcc<5 C. The distribution of the paraffins is determined by liquid/gas chromatography. With this method it is possible to determine the C9-C30 n-paraffin concentration in middle distillates.

[0034] In a first step, with liquid chromatography, it is possible to separate the middle distillate according to chemical families (saturated, mono-, di- and tri-aromatic families). As the n-paraffins are in the saturated fraction, the latter is recovered and injected on a gas chromatography column where the paraffins are separated according to their boiling temperature and therefore to their carbon number. Finally, the paraffins are quantified by calibration.

[0035] The filterability additives used are copolymers of ethylene and vinyl acetate referenced hereafter as EVAi in Table II hereafter.

TABLE-US-00002 TABLE II Viscosity at Vinyl acetate Molecular weight 100 C. (Pa .Math. s) content (weight %) Mw EVA 1 0.3 28 9,500 EVA 2 0.4 31 15,000 EVA 3 0.4 36 18,000 EVA 4 0.3 24 10,000

[0036] The revealing compounds used are polyacrylates referenced as Bi, the characteristics of which are given for 30% of active materials in an aromatic solvent of the Solvarex 10 type (aromatic hydrocarbon cut with 8 to 20 carbons and a boiling point varying from 140 to 320 C.) in Table III hereafter. As preparation examples, these polyacrylates are obtained by polymerization of the monomer under an inner nitrogen atmosphere as follows.

[0037] 100 parts of this monomer are melted beforehand in an oven at 70 C. and then solubilized in 158 parts of aromatic solvent (Solvarex 10 or Solvarex 150). The obtained mixture is continuously introduced for 6 hrs 30 and under stirring in a tank under a nitrogen atmosphere containing 75 parts by weight of aromatic solvent and 4 parts by weight of organic peroxide, this mixture having been raised beforehand to a temperature of 100 C. Throughout the addition, the set temperature is maintained at 100 C. The reactor is cooled and the resin is stabilized by adding 100 ppm of 4-methoxyphenol, in order to avoid post-polymerization of the residual monomers which may lead to a change in the average molar mass of the polymers during storage.

TABLE-US-00003 TABLE III Acid Density Mw, content at Viscosity Viscosity Mn by (mg 20 C. at 20 C. at 40 C. CPG Monomer KOH/g) (kg/L) (mm/s) (mm/s) (daltons) B1 C.sub.18/C.sub.22 1.5 0.895 15 5,000 15,000 acrylate B2 C.sub.30/C.sub.40 0.5 Not Solid Solid 6,770 acrylate measurable

Example 2

[0038] The present invention aims at showing the benefit of Bi revealing compounds according to the invention and their influence on the efficiency of LFT additives on distillates Fi of the invention and on Gi distillates. Table IV gathers the results obtained by comparing the efficiency of B1, either alone or in combination with the LFT additives EVA 1 and EVA 2 on the Fi and Gi distillates.

TABLE-US-00004 TABLE IV Amount in ppm G1 G2 F1 F2 F3 Distillate alone 4 8 1 0 7 Tcc 7 8.3 1.2 1.2 5 EVA 1 100 7 10 7 1 7 200 13 10 11 3 7 300 13 / / 4 7 EVA 2 100 8 9 4 3 / 200 11 17 3 2 / EVA1/B1 100 8 9 11 / / 95.5/4.5 200 11 10 10 6 7 300 14 / / 8 10 EVA2/B1 100 / 10 / / / 95.5/4.5 200 / 19 / 6 10 B1 4.5 4 8 1 0 7 9.5 4 8 1 1 8

[0039] It is observed that the Fi distillates with Tcc greater than 5 C. are not or not very reactive to EVAi alone but are reactive to synergic mixtures EVAi/Bi while the Gi distillates outside the invention with Tcc less than 5 C. are only reactive to the EVA alone. It is to be noted that the revealing compound B alone does also not show any LFT efficiency on either of the families of Fi or Gi distillates.

Example 3

[0040] The present example describes the influence of the relative concentration of the revealing compounds Bi and of the LFT additives EVAi on the reduction of LFT temperatures of Fi distillates typical of the invention. Table V gathers the filterability temperatures of the distillates F1 and F2 when the concentration of the revealing compound Bi is varied for variable concentrations of the EVAi/Bi composition.

TABLE-US-00005 TABLE V F 0 ppm 100 ppm 200 ppm F1 EVA1 1 7 11 F1 EVA1/B1: 97.8/2.2 1 13 11 F1 EVA1/B1: 95.5/4.5 1 11 10 F1 EVA1/B1: 90/10 1 11 11 G1 EVA1 4 15 17 G1 EVA1/B1: 96/4 4 15 17 G1 EVA1/B1: 92/8 4 12 14 G1 EVA1/B1: 82/18 4 8 11

[0041] The conducted tests by varying the EVA1/B1 ratio show in the case of Fi distillates, an optimum efficiency for small doses of revealing compound. When taking Gi distillates, a loss of efficiency of the EVA1s is seen on the contrary with increasing concentration of revealing compounds Bi, expressed by an increase in the filterability temperature of the distillate.

Example 4

[0042] The present example describes the preferred polymers of the invention selected from the polymers of olefinic esters of carboxylic acids and of an alcohol. The question is of describing the impact of the nature of the carboxylic acid and that of the chain length of the alcohol on the decrease of the filterability temperature of the F1 and F2 distillates. In the composition according to the invention, the content of homopolymers of olefinic esters of carboxylic acids and of an alcohol is 4.5% for an EVA1 content of 95.5%. The composition content in the distillates varies from 0 to 300 ppm in the present example.

[0043] The obtained results are gathered in Table VI hereafter,

TABLE-US-00006 TABLE VI Monomer used for Mw synthesizing the revealing (revealing compound B compound) 0 ppm 200 ppm 300 ppm F2 Without 1 4 3 F2 B1 C.sub.18/.sub.22 acrylate 13,370 1 -6 6 F2 C.sub.18-.sub.22 methacrylate 17,100 1 3 F2 C.sub.16 stearyl methacrylate 16,100 1 4 F2 C.sub.12 lauryl methacrylate 11,985 1 3 2 F2 C.sub.30/.sub.40 acrylate 6,764 1 0 7 F2 C.sub.16 stearyl acrylate 13,660 1 5 3 F2 C.sub.12 lauryl acrylate 14,030 1 3 4 F1 Without 1 7 11 F1 B1 C.sub.18-.sub.22 acrylate/2-ethyl- 7,649 1 0 1 hexyl acrylate: 80/20 F1 B1 C.sub.18-.sub.22/2-ethyl-hexyl 7,555 1 0 2 acrylate: 50/50 F1 B1 C.sub.18-.sub.22 acrylate/vinyl 9,701 1 0 2 acetate: 70/30 F1 B1 C.sub.18-.sub.22/isobomyl 8,382 1 0 1 acrylate: 70/30 F1 B1 C.sub.18-.sub.22 acrylate 8,000 1 11 10

[0044] The efficiency of the revealing compound varies depending on the chain length of the alcohol and on the nature of the carboxylic acid used for synthesizing the polyester. In Table VI above, efficiency tests were carried out with revealing compounds synthesized by homopolymerization of alkyl acrylates with a chain length varying from C.sub.12 to C.sub.40 (according to the operating procedure described in Example 1). These results clearly show that the positive effect of the revealing compound occurs for polymers consisting in majority of alkyl chains above C.sub.16. Best results are obtained with C.sub.18-C.sub.22 acrylate and C.sub.30-C.sub.40 acrylate.

[0045] Other tests by replacing the revealing compound B1 with polymers synthesized by copolymerization of the C.sub.18-C.sub.22 acrylate with vinyl acrylate (ratio: 70/30) or with 2-ethyl-hexyl acrylate (ratio 80/20 and 50/50) show that these copolymers are not efficient as compared with the corresponding C.sub.18-C.sub.22 homopolymers. They even have a detrimental effect as regards the LFT temperature of the distillates according to the invention. The nature of the carboxylic acid is also a significant parameter, the tests described above carried out by replacing B1 with homopolymers of esters of C.sub.12, C.sub.16 or C.sub.18-C.sub.24 methacrylic acids show that they are not as efficient as their homologs obtained by homopolymerization of esters of acrylic acid. This example actually shows that the required selection of the polyacrylates of the invention as a revealing compound of the efficiency of the filterability additives on the filterability temperature of the distillates of the type of the invention is not obvious in view of the prior art. Only with the synergic combination of the composition according to the invention, the problem of lowering the LFT temperature of distillates with Tcc greater than or equal to 5 C. may be solved.