WO2009106744A2 - Ethylene/vinyl acetate/unsaturated esters terpolymer as additive enchancing the low-temperature resistance of liquid hydrocarbons such as middle distillates and motor fuels or other fuels - Google Patents

Abstract

The invention pertains to the use, as an additive enhancing the low-temperature resistance and filterability of fuels, of at least one copolymer comprising from 78 to 87 mol% of at least one alpha-olefin, preferably at least ethylene, from 12 to 18 mol% of at least one vinyl ester, preferably at least vinyl acetate, from 1 to 4 mol% of at least one ester of alpha,beta unsaturated monocarboxylic acid, preferably at least 2-ethylhexyl acrylate.

Description

 TERPOLYMER ETHYLENE / VINYL ACETATE / UNSATURATED ESTERS

AS AN ADDITIVE IMPROVING COLD LIQUID HYDROCARBONS LIKE MEDIUM DISTILLATES AND

FUELS OR FUELS

Technical area.

The invention relates to the use of alpha-olefin, vinyl ester and alpha, beta-unsaturated carboxylic acid ester copolymers as additives for improving the cold-running performance of fuels and lubricants as well as fuel oils and lubricants. packages containing these copolymers. Prior art.

At reduced temperature, the hydrocarbon compositions, especially those based on middle distillate type containing paraffin waxes, such as for example diesel fuels and heating fuel oils have a significant decrease in their flow properties. It is well known that the crystallization of paraffins is a limiting factor for the use of middle distillates. Also, it is important to prepare diesel fuels adapted to the temperatures at which they will be used in motorized vehicles, that is to say to the surrounding climate. Generally, cold operability of fuels at -10 ° C is sufficient in many hot or temperate countries. But in cold climate countries, such as the Scandinavian countries, Canada, and Northeast Asian countries, fuel usage temperatures well below -20 ° C can be achieved. It is the same for domestic fuel stored outside buildings (houses, buildings, ...). This adequacy of the cold operability of the middle distillate type fuels is important, especially when the engines start cold. If the paraffins are crystallized at the bottom of the tank, they can be driven to start in the fuel system and particularly clog filters and prefilters arranged upstream of the injection systems (pump and injectors). Similarly for the storage of domestic fuel oils, paraffins precipitate at the bottom of the tank and can be driven and obstruct the pipes upstream of the pump and the boiler supply system (nozzle and filter). It is obvious that the presence of solids, such as paraffin crystals, prevents the normal circulation of the middle distillate.

To improve their circulation either in the engine or to the boilers, several types of additives have emerged. Initially, the oil industry focused on the development of so-called cold flow improvers (CFI), which promotes the dispersion of paraffin crystals and prevents them from organizing into large networks. , responsible for clogging the filter pores. These additives act mainly on the filterability limit temperature (TLF) and the pour point, but do not modify the cloud point.

The prior art has described numerous CFI additives (see for example US 3,048,479, US 3,627,838, US 3,790,359, US 3,961,961, EP 261,957) which are generally copolymers of ethylene and unsaturated esters, such as ethylene / vinyl acetate copolymers (EVA), ethylene / vinyl propionate (EVP), ethylene / vinyl ethanoate (EVE), ethylene / methyl methacrylate (EMMA), and ethylene / alkyl fumarate.

To improve the properties of conventional CFIs, the prior art also provides conventional CFI ethylene / unsaturated ester additive mixtures with lubricating agents (mono- or polycarboxylic acid esters and mono- or polyalcohols (see, for example EP 721 492), with anti-sedimentation agents (see, for example, FR 2 490 669), with ethers (see for example US Pat. No. 3,999,960, EP 1 87 488).

There are also improved CFI additives which are terpolymers or copolymers derived from more than 3 different monomers.

For example, US Pat. No. 6,509,424 describes a process for the preparation of terpolymers of ethylene and at least two compounds containing ethylenic unsaturations, such as vinyl esters, (meth) acrylic esters and alkyl vinyl ethers in a tubular reactor. . These terpolymers can be used as additives improving the cold flow of oils and petroleum distillates.

No. 3,642,459 discloses terpolymers comprising 40 to 89% by weight of ethylene, 10 to 40% by weight of vinyl ester derived from short chain (C2-C4) carboxylic acid, such as vinyl acetate, and unsaturated monoesters having a C10-C22 alkyl chain); these terpolymers are used as additives to lower the pour point of petroleum distillates and as anti-waxing agents and to improve their filterability. No. 4,156,434 describes terpolymers of ethylene, vinyl acetate and acrylic ester derived from C12-C24 alcohol which lower the pour point of the fuels in which they are incorporated, but nothing is said about improving the cold filterability of these additives.

WO 2005/054314 describes terpolymers of alpha olefin, vinyl ester and alpha-beta unsaturated mono carboxylic acid ester used. Are exemplified terpolymers, particularly preferred by the applicant, which contain more than 80 mol% of ethylene and less than 9 mol% of vinyl acetate. However, these terpolymers containing less than 9 mol% of vinyl acetate, although having an effect on the reduction of TLF for middle distillates containing more than 18% of n-paraffins, are not satisfactory for on the one hand solubility and secondly the tendency to clogging (or filterability at room temperature): there is harmful filter clogging.

EP 1,391,498 discloses additives improving the low temperature fluidity of middle distillates which are vinyl polymers (A), preferably ethylene-vinyl ester copolymers, the amount of hexane insoluble materials exceeding 60% by weight at -20 ° C and is less than 30% by weight at 10 ° C; the examples of EP 1.391.498 clearly show that the filterability temperature (CFPP) is lowered for copolymers and terpolymers whose amount of hexane-insoluble matter exceeds 60% by weight at -20 ^° C. and is less than 30% by weight at 10 ⁰ C relative to copolymers and terpolymers having the same units of recurrence present in the same proportions but the amount of hexane insoluble material is outside the range claimed; the copolymers exemplified are EVA copolymers and ethylene-vinyl acetate-neodecanoate or 2-ethylhexanoate vinyl terpolymers. There is an unresolved need for additives to improve the cold carrying capacity of the fuels (TLF and pour point) while reducing or even eliminating the risk of clogging, so as to avoid clogging the filters of the feed systems. engines or boilers (injection system and tanks). DESCRIPTION OF THE INVENTION The present invention relates to the use of copolymers as additives improving the cold resistance of fuels (CFI additives); these copolymers contain units derived from at least one alpha-olefin, at least one vinyl ester and at least one alpha-beta unsaturated mono carboxylic acid ester, and are preferably terpolymers of ethylene, vinyl acetate and ethyl-2-acrylate, hexyl. The copolymers according to the invention which can be used as CFI additives comprise

from 78 to 87 mol% of at least one alpha-olefin, preferably at least one of ethylene

From 12 to 18 mol% of at least one vinyl ester, preferably at least vinyl acetate, from 1 to 4 mol% of at least one unsaturated alpha-beta mono carboxylic acid ester, preferably at least 2-ethylhexyl acrylate.

Advantageously, the copolymers which can be used as CFI additives comprise: from 78 to 87 mol% of ethylene,

from 12 to 18 mol% of vinyl acetate, preferably from 12 to 16 mol%;

from 1 to 4 mol% of 2-ethylhexyl acrylate, preferably from 1.5 to 3.5 mol%, The copolymers according to the invention which are random copolymers have a number-average molecular weight (Mw) measured by GPC in general between 3,000 and 30,000, and a number average molecular weight (Mn) measured by GPC in general between 1,000 and 15,000.

These copolymers can be prepared in known manner by any polymerization process (see for example, Ullmann's Encyclopedia of Industrial Chemistry, 5 ^th Edition, "Waxes" Vol A 28, p.146;. US 3,627,838; EP 7590 ) in particular by radical polymerization, preferably under high pressure, typically of the order of 1000 to 3000 bar (100 to 300 MPa), preferably from 1500 to 2000 bar (150 to 200 MPa), the temperatures of reaction generally ranging from 160 to 320 ° C, preferably from 200 to 280 ° C, and in the presence of at least one radical initiator chosen in general from organic peroxides and / or oxygenated or nitrogen compounds, and from molecular weight regulator (ketone or aliphatic aldehyde, ...). The copolymers may, for example, be prepared in a tubular reactor according to the method described in US Pat. No. 6,509,424. The hydrocarbon-based compositions in which the copolymers according to the invention are incorporated are chosen from all types of fuel oils, such as diesel fuels, domestic fuel for heating installations (FOD), kerosene, aviation fuel oil, heavy fuel oil, etc.

In general the sulfur content of the hydrocarbon compositions is less than 5000 ppm, preferably less than 500 ppm, and more preferably less than 50 ppm, or even less than 10 ppm and advantageous without sulfur.

The hydrocarbon-based compositions comprise middle distillates having a boiling point of between 100 and 500 ° C .; their starting crystallization temperature Tcc is often greater than or equal to -20 ^° C., generally between -15 ^° C. and +10 ^° C. These distillates may, for example, be chosen from distillates obtained by the direct distillation of crude hydrocarbons, vacuum distillates, hydrotreated distillates, distillates from catalytic cracking and / or hydrocracking of vacuum distillates, distillates resulting from ARDS type conversion processes (by residue desulfurization atmospheric) and / or visbreaking, distillates derived from the recovery of Fischer Tropsch slices, distillates resulting from the BTL (biomass to liquid) conversion of plant and / or animal biomass, taken alone or in combination and / or the esters vegetable and animal oils or mixtures thereof.

The hydrocarbon compositions may also contain distillates resulting from more complex refining operations than those resulting from the direct distillation of hydrocarbons which may for example be derived from cracking, hydrocracking and / or catalytic cracking processes and visbreaking processes.

They may also contain new sources of distillates, among which may be mentioned in particular:

the heaviest cuts resulting from cracking and visbreaking processes concentrated in heavy paraffins, comprising more than 18 carbon atoms,

synthetic distillates resulting from gas transformation, such as those derived from the Fischer Tropsch process,

synthetic distillates resulting from the treatment of biomass of plant and / or animal origin, such as in particular NexBTL, and oils and / or esters of vegetable and / or animal oils,

- or biodiesel of animal and / or vegetable origin.

These new fuel bases can be used alone or in combination with conventional middle oil distillates as fuel base and / or base of domestic fuel oil; they generally comprise long paraffinic chains greater than or equal to 10 carbon atoms and preferably C14 to C30.

The copolymers as defined previously of Mw between 5,000 and 27,000 and Mn between 1,500 and 22,000, preferably Mw between 5,000 and 25,000 and Mn between 1,500 and 20,000 are particularly effective. when they are incorporated in light middle distillates and / or low sulfur (typically less than 50 ppm) and / or low initial crystallization temperature (typically up to -20 ° C). By light middle distillates are meant distillates whose n-paraffin content having 24 or more carbon atoms ranges from 0 to about less than 0.7% by weight of the total fuel composition; of which the C18-C23 n-paraffins represent about 3 to about 5% of the total weight of the fuel and whose mass ratio of C18-C23 n-paraffins to paraffins C24 and higher is generally from 10 to 35.

The copolymers of Mw ranging from 5,000 to 10,000 and Mn ranging from 1

500 and 8000, preferably Mw between 5000 and 8000 and Mn between 1500 and 5000 are particularly effective when incorporated in heavy middle distillates and / or at a rather high starting crystallization temperature.

(typically ranging from 0 to 15 ° C). Heavy middle distillates are distillates whose n-paraffin content with 24 or more carbon atoms ranges from about 0.7 to about 2% by weight of the total fuel composition; wherein the C18-C23 n-paraffins represent about 1 to about 10% of the total weight of the fuel and whose mass ratio of C18-C23 n-paraffins to C24 + paraffins generally ranges from 1 to 10.

The copolymers may be added as such in the hydrocarbon compositions or, preferably, in the form of concentrated solutions, in particular solutions containing from 50 to 80%, preferably from 60 to 70% by weight of copolymer (s) in a mixture. solvent, such as aliphatic or aromatic hydrocarbons, alone or as a mixture (naphtha, kerosene, hydrocarbon fractions, such as solvent Solvesso, paraffinic hydrocarbons, such as pentane, hexane.

According to a preferred embodiment of the invention, the hydrocarbon compositions comprise from 10 to 5000 ppm by weight of at least one copolymer described above, preferably from 100 to 1000 ppm, and advantageously from 150 to 500. ppm.

In addition to the CFI additives or cold-holding additives described above, the hydrocarbon compositions may also contain one or more other additives different from the copolymers according to the invention, chosen from detergents, anti-corrosion agents, dispersants, demulsifiers, defoamers, biocides, deodorants, procetane additives, friction modifiers, lubricity additives or lubricity additives, combustion assistants (catalytic combustion promoters and soot) , cloud point improvers, pour point, filterability limit temperature, anti-settling agents, anti-wear agents and / or conductivity modifiers.

Among these additives, mention may be made especially of: a) procetane additives, in particular (but not limited to) selected from alkyl nitrates, preferably 2-ethyl hexyl nitrate, aroyl peroxides, preferably benzyl peroxide, and alkyl peroxides, preferably ter-butyl peroxide; b) anti-foam additives, in particular (but not limited to) selected from polysiloxanes, oxyalkylated polysiloxanes, and fatty acid amides from vegetable or animal oils. Examples of such additives are given in EP 861 882, EP 663 000, EP 736 590; c) detergent and / or anti-corrosion additives, in particular (but not limited to) selected from the group consisting of amines, succinimides, alkenylsuccinimides, polyalkylamines, polyalkyl polyamines and polyetheramines. Examples of such additives are given in EP 938,535. D) lubricant additive or anti-wear agent, in particular (but not limited to) selected from the group consisting of fatty acids and their ester or amide derivatives, in particular glycerol monooleate , and mono- and polycyclic carboxylic acid derivatives. Examples of such additives are given in the following documents: EP 680 506, EP 860 494, WO 98/04656, EP 915 944, FR 2 772 783, FR 2 772 784. e) cloud point additives, in particular (but not limited to) selected from the group consisting of long chain olefin / meth (meth) acrylic / maleimide terpolymers, and fumaric / maleic acid ester polymers. Examples of such additives are given in EP 71 513, EP 100 248, FR 2 528 051, FR 2 528 051, FR 2 528 423, EP 1 12 195, EP 1 727 58, EP 271 385, EP 291367; f) anti-sedimentation additives and / or paraffin dispersants, in particular (but not limited to) selected from the group consisting of (meth) acrylic acid / polyamine-amidated alkyl (meth) acrylate copolymers, alkenylsuccinimides of polyamine, phthalamic acid derivatives and fatty amine double chain; alkyl phenol resins. Examples of such additives are given in EP 261,959, EP593,331, EP 674,689, EP 327,423, EP 512,889, EP 832,172; US 2005/0223631; US 5,998,530; WO 93/14178. g) polyfunctional cold operability additives selected from the group consisting of olefin and alkenyl nitrate polymers as described in EP 573 490.; h) other CFI additives improving the cold resistance and the filterability, such as EVA and / or EVP copolymers

These other additives are generally added in an amount ranging from 100 to 1000 ppm (each). The improved cold-strength additives according to the invention may be added to the hydrocarbon compositions within the refinery, and / or may be incorporated downstream of the refinery, optionally mixed with other additives, in the form of a package. additives.

Examples

In a tabular reactor, high-pressure radical polymerization (1400 to 2500 bar (140 to 250 MPa)) and a polymerization temperature of 200 to 280 ^° C. are synthesized using terpolymers of ethylene and vinyl acetate. and 2-ethylhexyl acrylate. The synthesis is carried out using aliphatic aldehyde (propanal) to control molecular weights and using peroxides as polymerization initiators. In Table 1 below, the Mn and Mw of the synthesized terpolymers and their percentages of the monomers are indicated.

Table 1: Characteristics of synthesized polymers

On évalue l'aptitude à l'amélioration de la tenue à froid de ces terpolymères en les incorporant dans des 6 distillats de type gazole moteur appelé GOM 1 à GOM 6 dont les caractéristiques sont réunies dans le tableau 2 ci-dessous

The ability to improve the cold strength of these terpolymers is evaluated by incorporating them into 6 diesel engine type distillates called GOM 1 to GOM 6, the characteristics of which are shown in Table 2 below.

Table 2: Fuel Characteristics

400 ppm by weight of each copolymer 1 to 16 below is incorporated into the diesel engine type distillate called GOM 1 and then the Filter Blocking Tendency (FBT) is measured according to the IP 387 standard. GOM 1 without additive has an FBT clogging index of 1.01. It can be seen that the terpolymers according to the invention make it possible not to degrade the tendency to clog the GOM 1, ie that the GOM 1 additive with 400 ppm of terpolymer has an FBT of less than 1.41. The results are shown in Table 3 below Table 3 Clogging tendency (IP387) of the GOM 1 additive at 400 ppm of the different terpolymers.

The cold-holding efficiency TLF of the terpolymers incorporated in the GOM 2 to GOM 6 at the concentration of 140 is measured; 210 or 280 ppm; the results are shown in Table 4.

Table 4: TLF efficiency tests on various low sulfur gas oils.

It is found that the terpolymers 1; 2; 3; 4 according to the invention are the most effective on the different gas oils GOM 2 to GOM 6. Furthermore, from the results of Table 3, it is found that these terpolymers 1; 2; 3 and 4 added at 400 ppm in GOM 1 do not degrade the clogging tendency. This is not the case of comparative terpolymers 6; 7; 8; 9; 1 and 16 according to WO 2005/054314 which greatly degrade the tendency to clogging measured according to ITP 387 and are not as effective in TLF as the additives of the invention, for example additives 1; 2; 4 and 5.

Claims

1. Use as an additive improving the cold resistance and filterability of fuels of at least one copolymer comprising "from 78 to 87 mol% of at least one alpha-olefin, preferably at least ethylene, from 12 to 18 mol% of at least one vinyl ester, preferably at least vinyl acetate, from 1 to 4 mol% of at least one alpha-beta unsaturated mono carboxylic acid ester, preferably at least 2-ethylhexyl acrylate. 2. Use according to claim 1 of at least one terpolymer comprising from 78 to 87 mol% of ethylene, from 12 to 18 mol% of vinyl acetate, from 1 to 4 mol% of 2-ethylhexyl acrylate. 3. Use according to claim 1 or 2 of at least one number-average molecular weight (Mw) copolymer measured by GPC of between 3,000 and 30,000, preferably 3,000 to 20,000, and a number-average molecular weight (Mn). measured by GPC in general between 1000 and 20000, preferably ranging from 1500 to 15000. 4. Use according to claim 1 to 3 of at least one copolymer as an additive improving the cold resistance and filterability without deterioration of the clogging tendency of middle distillates, such as diesel fuels, domestic fuel for heating installations (FOD). , kerosene, aviation fuel oil, heavy fuel oil. 5. Use according to any one of claims 1 to 4 of at least one copolymer as an additive improving the cold resistance and the filterability of fuels with a sulfur content of less than 5000 ppm, preferably less than 500 ppm, more preferably less than 50 ppm, or even less than 10 ppm and advantageous without sulfur. A hydrocarbon composition comprising a major amount of an average distillate having a boiling point of from 100 to 500 ° C and a minor amount of at least one copolymer as defined in any one of claims 1 to 5. . 7. Composition according to claim 6, characterized in that it contains from 0 to 100% by weight of biodiesel of animal and / or vegetable origin. 8. Composition according to claim 6 or 7, characterized in that it is selected from diesel fuels, domestic fuel for heating installations (FOD), kerosene, aviation fuel oil, heavy fuel oil. 9. Composition according to any one of claims 6 to 8, characterized in that it comprises from 10 to 5000 ppm by weight of at least one copolymer as defined in claims 1 to 5, preferably from 100 to 1000 ppm, and preferably from 150 to 500 ppm. 10. Composition according to any one of claims 6 to 9, characterized in that it comprises one or more other additives different from the copolymers according to the invention, selected from detergents, anti-corrosion agents, dispersants, demulsifiers anti-foam agents, biocides, deodorants, procetane additives, friction modifiers, lubricity additives or lubricity additives, combustion assistants (catalytic combustion promoters and soot), cloud point improving agents, pour point, filterability limit temperature, anti-settling agents, anti-wear agents and / or conductivity modifiers.