WO1994006892A1

WO1994006892A1 - Oligomeric/polymeric multifunctional additives to improve the low-temperature properties of distillate fuels

Info

Publication number: WO1994006892A1
Application number: PCT/US1993/008794
Authority: WO
Inventors: David Joseph Baillargeon; Angeline Baird Cardis; Dale Barry Heck; Susan Wilkins Johnson
Original assignee: Mobil Oil AS
Current assignee: Mobil Oil AS
Priority date: 1992-09-17
Filing date: 1993-09-17
Publication date: 1994-03-31
Anticipated expiration: 1995-03-17
Also published as: FI951234L; FI951234A0; EP0660868A1; EP0660868A4; CA2143097A1; AU4927493A; FI951234A7; US5284496A; AU670322B2

Abstract

Additives which improve the low-temperature properties of distillate fuels are oligomeric/polymeric reaction products of anhydrides and long-chain epoxides (or their corresponding acid/diol equivalents) consisting of hydroxyl promoted polyesters and ester promoted polyesters.

Description

892 __χ_ P T U

OLIGOMERIC/POLYMERIC MULTIFUNCTIONAL ADDITIVES

TO IMPROVE THE LOW-TEMPERATURE PROPERTIES OP

DISTILLATE FUELS

This application is directed to oligomeric/ polymeric multifunctional additives comprised of hydroxyl promoted ester materials, and ester promoted polyester materials useful for improving the low- temperature properties of distillate fuels and to fuel compositions containing same. Traditionally, the low-temperature properties of distillate fuels have been improved by the addition of kerosene, sometimes in very large amounts (5-70 wt %) . The kerosene dilutes the wax in the fuel, i.e., lowers the overall weight fraction of wax, and thereby lowers the cloud point, filterability temperature, and pour point simultaneously.

Other additives known in the art have been used in lieu of kerosene to improve the low-temperature properties of distillate fuels. Many such additives are polyolefin materials with pendent fatty hydrocarbon groups. These additives are limited in their range of activity; however, most improve fuel properties by lowering the pour point and/or filterability temperature. These same additives have little or no effect on the cloud point of the fuel.

The additives of this invention effectively lower distillate fuel cloud point and cold filter plugging point (CFPP) , and thus provide improved low-temperature fuel properties, and offer a unique and useful advantage over known distillate fuel additives.

Novel polyester and modified polyester polymers have been prepared from (1) anhydrides or acid equivalents, long-chain epoxides or diol equivalents and epoxidized fatty esters, and (2) from anhydrides, long-chain epoxides and co-reacted polyalcohols and have been found to be surprisingly active wax crystal modifier additives for distillate fuels. Distillate fuel compositions containing < 0.1 wt% of such additives demonstrate significantly improved low- temperature flow properties, i.e., lower cloud point and lower CFPP filterability temperature. In addition, additives from (1) and (2) above in combination with a pour point additive achieve additional performance improvements, especially in lowering cloud point of the treated fuel.

These additives are oligomeric and/or polymeric ester products which have linear hydrocarbyl pendant groups attached to the backbone of the oligomeric/polymeric structure. These esters are derived from the polymerization of a suitable combination of monomers which include (1) one or more epoxides, (2) one or more anhydrides, and (3) a reactive material, e.g., epoxidized fatty ester, isocyanates, epoxy halides, diepoxides, carbamates, dianhydrides or polyols, etc., which may function as a chain transfer agent, chain terminator, chain propagator, or chain cross-linking agent. Alternatively, condensation reaction with removal of water or other such by-product may be employed to make the same oligomeric/polymeric esters from a monomer mixture which may include (1) one or more long-chain diolε, (2) one or more diacid equivalents (anhydride, diacid, diacid chloride, etc.), and (3) the same reactive materials listed above.

Additionally, the oligomeric and/or polymeric ester products, derived as described above, may be further reacted with additional reagents in a second synthetic step so as to derivatize, cap, or otherwise modify reactive end groups or other pendant groups incorporated along the backbone of the original oligomeric/polymeric ester. These additional reagents may include, for example, amines or alcohols which 892 _-3,_-

would serve to convert residual acids and anhydrides in the oligomeric/polymeric ester product to alternate carboxyl derivatives such as amides, imides, salts, esters, etc. Similarly, residual epoxides would be converted to amine and ether adducts. These examples serve to illustrate, but not limit, the concept of post-reacting the original oligomeric/polymeric ester product to modify its original chemical functionality.

These oligomeric/polymeric esters are structurally very different from the known categories of polymeric wax crystal modifiers. Known polymeric wax crystal modifiers are generally radical-chain reaction products of olefin monomers, with the resulting polymer having an all-carbon backbone. The materials of this invention are condensation products of epoxides (or diols) and anhydrides (or acid equivalents) to give polymeric structures where ester functions are regularly spaced along the polymer backbone.

These new additives are especially effective in lowering the cloud point of distillate fuels, and thus improve the low-temperature flow properties of such fuels without the use of any light hydrocarbon diluent, such as kerosene. In addition, the filterability properties are improved as demonstrated by lower CFPP temperatures. Thus, the additives of this invention demonstrate multifunctional activity in distillate fuels.

The compositions of these additives are unique.

Also, the additive concentrates and fuel compositions containing such additives are unique. Similarly, the processes for making these additives, additive concentrates, and fuel compositions are unique.

The primary object of this invention is to improve the low-temperature flow properties of distillate fuels. These new additives are especially effective in lowering the cloud point of distillate fuels, and thus improve the low-temperature flow properties of such fuels without the use of any light hydrocarbon diluent, such as kerosene. In addition, the filterability properties are improved as demonstrated by lower CFPP temperatures. Thus, the additives of this invention demonstrate multifunctional activity in distillate fuels.

The additives of this invention have comb-like structures, where a critical number of linear hydrocarbyl groups are attached to the backbone of an oligomeric/polymeric polyester. These additives are reaction products obtained by combining two, or optionally more, monomers in differing ratios using standard techniques for condensation polymerization. These wax crystal modifiers which are effective in lowering cloud point are generally characterized as alternating co-oligomers/copolymers (or optionally terpolymers, etc.) of the following type: (-A-B)n;

(-A-A'-B)n; (-A-B-B')n; or (-A-B-C-)n where n >. 1, A or A' is one or more anhydrides or diacid equivalents, B or B' is one or more epoxides or diols and C is said reactive material. One combination of monomers may include (A) one or more anhydrides, (B) one or more long-chain epoxides, and (C) a reactive material, e.g., isocyanates, epoxy halides, diepoxides, carbamates, dianhydrides or polyols, etc., which may function as a chain transfer agent, chain terminator, chain propagator, or chain cross-linking agent. Alternatively, a second combination of monomers, in which the removal of a low molecular weight by-product accompanies the condensation reaction, may include (A) one or more diacid equivalents (anhydride, diacid, diacid chloride, etc.), (B) one or more diols, and (C) the same reactive materials listed above. Comonomer stoichiometry may vary widely with A:B = 1:2 to 2:1, or preferably A:B = 1:1.5 to 1.5:1, or most preferably A:B = 1:1.1 to 1.1:1. Termonomers, component C, may substitute for some fraction of A or B in the above stoichiometric ranges.

The pendant linear hydrocarbyl groups are carried by at least one, and optionally by more than one, of the monomers. These critical linear pendant hydrocarbyl groups are generally C-₂ or longer.

Additives of this invention may be grouped into categories based on distinct structural and compositional differences, described below.

Preparation of selected additives are given in EXAMPLES

1-2. Additive compositions and their respective performance for cloud point and CFPP are given in

TABLES 1-2. Category A: Hydroxyl-Promoted Ester Compositions (TABLE 1)

Successful wax crystal modifier additives may be obtained as mixtures of (1) ABC-type oligomers/polymers which can be prepared from an anhydride (A monomer) , a long-chain epoxide (B monomer) , and a co-reacted polyalcohol (C monomer) using an amine catalyst, and additionally (2) a common pour point reducing additive, for example, ECA 12513. "ECA" is used to signify an ethylene polymer containing carboxylic acid groups along the polymer chain. This includes polymers wherein there can be a minor amount of one or more other copolymerizable unsaturated monomers. The polyalcohol renders the oligomer/polymer composition susceptible to a significant and beneficial synergistic interaction with the pour point additive to improve diesel fuel cloud point. The impact of adding pour point additive, e.g., ECA 12513, to the hydroxyl- promoted oligomeric/polymeric ester composition is evident in Table 1 where the improvements in diesel fuel cloud point are shown. The polyalcohols used in this invention may include polyols (Entries 124-127) as well as aminopolyols (Entries 128-135) . The pour point additives which may be used in this invention include any of the polyolefin type polymers in which pendant linear hydrocarbyl groups are attached directly to the polymer backbone, and/or attached via ester, amide, ammonium salts, or other functional groups to the polymer backbone. The specific pour point additive used in these examples is ECA 12513. Preparation of a typical additive composition, including the synthesis of a dipentaerythritol-promoted phthalate oligomer/polymer (Entry 125) , is given in

EXAMPLE 1.

Category B: Ester-Promoted Polyester Compositions (TABLE 2)

Successful wax crystal modifier additives may be obtained as mixtures of (1) ABC-type oligomers/polymers which can be prepared from an anhydride (A monomer) , a long-chain epoxide (B monomer) , and an epoxidized fatty ester (C monomer) using an amine catalyst, and additionally (2) a common pour point reducing additive, for example, ECA 12513. When incorporated into the reaction product of (1) , the epoxidized fatty ester provides ester functional groups which are pendant from the oligomer/polymer backbone. More importantly, the epoxidized fatty ester renders the final oligomer/polymer susceptible to a significant additional and beneficial synergistic interaction with a pour point additive to improve diesel fuel cloud point. Any of the anhydride/epoxide compositions described previously are suited to this additional modification. The impact of adding pour point additive, e.g., ECA 12513, to the ester-promoted oligomeric/ polymeric ester composition is evident in Table 2 where the improvements in diesel fuel cloud point are shown. Various epoxidized fatty esters were selected in making the modified oligomers/polymers described above (Entries 136-141) , and they may be used in concentrations of 0.001 wt% or higher. The pour point additives which may be used in this invention include any of the polyolefin type polymers in which pendant linear hydrocarbyl groups are attached directly to the polymer backbone, and/or attached via ester, amide, ammonium salts, or other functional groups to the polymer backbone. The specific pour point additive used in these examples is ECA 12513.

Preparation of a typical additive composition, including the synthesis of an epoxidized fatty ester- promoted phthalate oligomer/polymer (Entry 136, Table 2) , is given in EXAMPLE 2.

Generally speaking, the reactions can be carried out under widely varying conditions which are not believed to be critical. The reaction temperatures can vary from about 50 to 250^βC, under ambient or autogenous pressure. However, slightly higher pressures up to about 100 psi may be used if desired. The temperatures chosen will depend upon for the most part on the particular reactants and on whether or not a solvent is used. Reactants may be run with or without solvents. Solvents, if used, will typically be hydrocarbon solvents such as xylene, but any non-polar, unreactive solvent can be used including benzene and toluene and/or mixtures thereof. Molar ratios, less than molar ratios or more than molar ratios of the reactants can be used. The times for the reactions are also not believed to be critical. The process is generally carried out in from about one to twenty-four hours or more.

In general, the reaction products of the present invention may be employed in any amount effective for imparting the desired degree of activity to improve the low temperature characteristics of distillate fuels. In many applications the products are effectively employed in amounts from about 0.001% to about 10% by weight and preferably from less than 0.01% to about 5% of the total weight of the composition.

These additives may be used in conjunction with other known low-temperature fuel additives (dispersants, etc.) being used for their intended purpose.

The fuels contemplated are liquid hydrocarbon combustion fuels, including the distillate fuels and fuel oils. Accordingly, the fuel oils that may be improved in accordance with the present invention are hydrocarbon fractions having an initial boiling point of at least about 250"F and an end-boiling point no higher than about 750°F and boiling substantially continuously throughout their distillation range. Such fuel oils are generally known as distillate fuel oils. It is to be understood, however, that this term is not restricted to straight run distillate fractions. The distillate fuel oils can be straight run distillate fuel oils, catalytically or thermally cracked (including hydrocracked) distillate fuel oils, or mixtures of straight run distillate fuel oils, naphthas and the like, with cracked distillate stocks. Moreover, such fuel oils can be treated in accordance with well-known commercial methods, such as, acid or caustic treatment, hydrogenation, solvent refining, clay treatment, etc. The distillate fuel oils are characterized by their relatively low viscosities, pour points, and the like. The principal property which characterizes the contemplated hydrocarbons, however, is the distillation range. As mentioned hereinbefore, this range will lie between about 250^βF and about 750^βF. Obviously, the distillation range of each individual fuel oil will cover a narrower boiling range falling, nevertheless, within the above-specified limits. Likewise, each fuel oil will boil substantially continuously throughout its distillation range.

Contemplated among the fuel oils are Nos. 1, 2 and 3 fuel oils used in heating and as diesel fuel oils, and the jet combustion fuels. The domestic fuel oils generally conform to the specification set forth in A.S.T.M. Specifications D396-48T. Specifications for diesel fuels are defined in A.S.T.M. Specification D975-48T. Typical jet fuels are defined in Military Specification MIL-F-5624B. In general, the reaction products of the present invention may be employed in any amount effective for imparting the desired degree of activity to improve the low temperature characteristics of distillate fuels. In many applications the products are effectively employed in amounts from about 0.001% to about 10% by weight and preferably from less than 0.01% to about 5% of the total weight of the composition.

EXAMPLE 1 Preparation of Additive Entry 125 (Table l) Phthalic anhydride (29.6 g, 0.20 mol; e.g., from Aldrich Chemical Co.), dipentaerythritol (5.09 g, 0.020 mol; e.g., from Aldrich Chemical Co.), 1,2- epoxyoctadecane (57.0 g, 0.20 mol; e.g., Vikolox 18 from Viking Chemical), triethylamine (0.41 g, 0.004 mol; e.g., from Aldrich Chemical Co.), and 4- dimethylaminopyridine (0.12 g, 0.001 mol; e.g., DMAP from Nepera, Inc.) were combined and heated at 120- 200°C for 5 hours. The reaction mixture was then hot filtered through a mixed bed of alumina (approximately 20%) and Celite to give 75.6 g of the final product.

EXAMPLE 2 Preparation of Additive Entry 136 (Table 2) Phthalic anhydride (31.2 g, 0.21 mol; e.g., from Aldrich Chemical Co.), epoxidized methyl soyate (2.54 g, 0.010 mol; e.g., Vikoflex 7010 from Viking Chemical), 1,2-epoxyoctadecane (57.0 g, 0.20 mol; e.g., Vikolox 18 from Viking Chemical), triethylamine (0.43 g, 0.004 mol; e.g., from Aldrich Chemical Co.), and 4- dimethylaminopyridine (0.13 g, 0.001 mol; e.g., DMAP from Nepera, Inc.) were combined and heated at 110"C/5 hours and 140^βC/l hour. The reaction mixture was then hot filtered through a mixed bed of alumina (approximately 20%) and Celite to give 79.0 g of the final product. PREPARATION OF ADDITIVE CONCENTRATE

A concentrate solution of 100 ml total volume was prepared by dissolving 10 g of additive in mixed xylenes solvent. Any insoluble particulates in the additive concentrate were removed by filtration before use. Any suitable hydrocarbon solvent such as xylene, mixed xylenes or toluene can be used. TEST FUELS

The following test fuel was used for the screening of additive activity:

API Gravity 31.5 Cloud Point (°F) 21.4

CFPP (°F) 14

Pour Point (°F) 10

Distillation (°F; D 86) IBP 340

10% 439 50% 534

90% 640

FBP 693

The cloud point of the additized distillate fuel was determined using an automatic cloud point test based on the commercially available Herzog cloud point tester; test cooling rate is approximately l^βC/minute. Results of this test protocol correlate well with ASTM D2500 methods. The test designation (below) is "HERZOG".

The low-temperature filterability was determined using the Cold Filter Plugging Point (CFPP) test. This test procedure is described in "Journal of the

Institute of Petroleum", Volume 52, Number 510, June

1966, pp. 173-185.

Test results are recorded in Tables 1-2.

10

15

20

TABLE 2: ESTER-PROMOTED POLYESTER/POUR POINT (ECA 12513) ADDITIVES CATEGORY B: ESTER-MODIFIED POLYESTERS

PERFORMANCE IMPROVEMENT (F):

"POLYESTER/

"POLYESTER" PP ADDITIVE"

MOLE CLOUD POINT CLOUD POINT

ENTRY EPOXIDE EPOXIDIZED ESTER ANHYDRIDE RATIO (HERZOG) CFPP HERZOG CFPP ppm ADDITIVE; 200 ppm ECA 12513

Vikoflex 7010 Phthalic Anhy 0 4.5 4

10 Vikoflex 7010 Phthalic Anhy 4 3.6 4

Vikoflex 7010 Phthalic Anhy 0 3.8 4

Vikoflex 5075 Phthalic Anhy 2 4.3 6

Vikoflex 9010 Phthalic Anhy 0 4.1 4

Vikoflex 9010 Phthalic Anhy

2 3.4 2

APPENDIX 1. GLOSSARY

CFPP: cold filter plugging point

DMAP: 4-dimethylamino-pyridine

Herzog: cloud point test; Herzog method

Phthalic anhydride: 1,2-benzenedicarboxylic anhydride

Quadrol : tetrahydroxypropyl ethylenediamine

Vikoflex 7010: epoxidized methyl soyate

Vikoflex 9010: epoxidized methyl linseedate

Vikolox "N": Linear 1,2-epoxyalkane, where N = the carbon number of the alkyl chain; N = 12, 14, 16, 18, 20, 20- 24, 24-28, 30+.

Claims

—IS¬O-AIM-.:

1. A multifunctional lσw-teπ erature-modifying distillate fuel additive comprised of a polymeric and/or oligomeric ester additive product of reaction consisting of hydroxyl promoted polyester materials and ester promoted polyester materials prepared by polymerizing or oligomerizing a suitable cαnbination of monomers selected from the group consisting of (1) one or more long-chain epoxides or diol equivalents, (2) one or more anhydrides or acid equivalents, and either (a) one or more epoxidized fatty esters or (b) one or more polyalcchols, and optionally (3) a suitable reactive material vmder suitable conditions of time, teirperature and pressure thereby producing the desired ester additive product said product containing polymeric structures having ester functions and long-chain hydroca-±yl groups irx-tependeπtly and regularly spaced along the polymer backbone.

2. The additive product of claim 1 wherein said reactive material is selected from the group consisting of epoxidized fatty esters, isocyanates, diisocyanates, epoxy halides, carbamates, diepoxides or diarihydrides.

3. The additive product of claim 1 wherein at least one of said monomers and optionally more than one, has a pendant hydrocarbyl group of at least C., or longer and wherein hydrocarbyl is selected from the group consisting of alkyl, alkeπyl, aryl, alkaryl, aralkyl and optionallymay be cyclic or polycyclic.

4. The additive product of claim 1 wherein the product is post reacted with amines, alcohols or mixtures of amines and alcohols.

5. The product of claim 1 wherein the monαπtiers are phthalic anhydride, dipentaerythritol and 1,2-epoxyoctadecane.

6. The product of claim 1 wherein the monomers are phthalic anhydride, epoxidizedmethyl sσyate and 1-2-epoxyoctadecane.

7. The additive reaction products of claim 1 prepared from the monomers and/or reactive materials and in the specified molar ratios, as set forth in Tables 1 and 2.

8. A process of preparing a multifunctional low-temperature modifying distillate fuel polymeric and/or oligomeric ester product of reaction ccπaprised of hydroxyl prorated polyester materials and ester promoted polyester materials ccπprising polymerizing or oligomerizing a suitable combination of αnαners selected from the group consisting of one or more lαng-chain epoxides or diol equivalents, one or more anhydrides or acid equivalents, and either (1) one or more epoxidized fatty esters, or (2) one or more polyalcohols, and optionally a suitable reactivematerial in varyingmolar ratios under suitable conditions of time, temperature and pressure ccπprising molar ratios varying from equimolar to more than molar to less than molar, at temperatures varying from about 50 to about 250°C, pressures varying from atmospheric to about 100 psi, for times varying from about an hour to 48 hours or more thereby producing the desired ester additive product said product ∞rϊtaiir-ing polymeric structures having ester functions and long-chainhydrocarfcyl groups inblependently and regularly spaced along the polymer backbone.

9. The process of claim 8 wherein said reactive material is selected from the group consisting of epoxidized fatty esters, isocyanates, diisocyanates, epαxy halides, carba ates, diepoxides or diahhydrides.

10. ϊhe process of claim 8 wherein at least one of said monomers and optionally more than one, has a pendant hydrocartyl group of at least C-_ or longer and wherein hydrocarbyl is selected from the group consisting of alkyl, alkeπyl, aryl, alkaryl, aralkyl and optionally may be cyclic or polycylic.

11. The process of claim 8 wherein the product is post reacted with a suitable reagent.

12. The process of claim 8 wherein the monoaτιers are phthalic anhydride, 1,2-epσxyoctadecane, and epoxidized methyl sσyate.

13. The process of claim 8 wherein the monomers are phthalic anhydride, dipentaerythritol and 1,2-epαxyoctadecane.

14. The process of claim 8 wherein the additive products are prepared fromthemαnoπαers and/or reactive materials, and in the specified molar ratios, as set forth in Tables l and 2.

15. The fuel additive concentrate of claim 14 whereby any sample of total volume of about 100 ml contains about 10 g of said additive dissolved therein.

16. The fuel additive concentrate of claim 14 wherein said solvent is selected from the group cαnsisting of xylene, mixed xylenes and toluene.

17. A liquid hydrocarbyl fuel composition ccraprising a major amount of said fuel and a minor amount of a multifunctional low-temperature modifying distillate fuel polymeric and/or oligomeric ester additive product of reaction comprised of hydroxyl promoted polyester materials and ester promoted polyester materials prepared by polymerizing or oligomerizing a suitable combination of monomers selected fom the group σor-sisting of one or more long-chain epoxides or diol equivalents, one or more anhydrides or acid equivalents, and either (1) one or more epoxidized fatty ester, or (2) one or more co-reacted polyalcohols, and optionally a suitable reactive material in varying molar ratios under suitable conditions of time, temperature and pressure thereby producing the desired ester additive product said product ∞ntainirig polymeric structures having ester functions and lαng-chain hydrocarbyl groups independently and regularly spaced along the polymer backbone.

18. The fuel composition of claim 17 wherein a minor amount of from about 0.001 to about 10 wt% of a suitable distillate fuel pour point additive is added thereto.

19. The fuel ccπposition of claim 17 wherein said reactive material is selected from the group consisting of isocyanates, diisocyanates, epαxy halides, carbamates, diepoxides or diarihydrides.

20. The fuel composition of claim 17 wherein at least one of said monomers and optionally more than one, has a pendant hydrocarbyl group of at least C^ or longer and wherein hydrocarbyl is selected from the group consisting of alkyl, alkeπyl, aryl, alkaryl, aralkyl and optionallymay be cyclic or polycylic.

21. The fuel composition of claim 17 wherein the monomers and reactive material are respectively phthalic anhydride and 1,2-epoxyoctadecane, and epoxidized methyl scyate.

22. The fuel composition of claim 17 wherein the iranσmers and reactive material are respectively phthalic anhydride, dipeπtaerythritol and 1,2-epoxyoctadecane.

23. The fuel compositions of claim 18 wherein the additive products are prepared from the monomers and/or reactive materials, and in the specified, molar ratios as set forth in Tables 1 and 2.