Wax Inhibitors With Improved Flowability

Abstract

This invention provides a wax inhibitor composition comprising A) the reaction product obtainable by reaction of i) a carboxylic acid containing an optionally substituted cycloaliphatic hydrocarbyl residue with ii) an alkylene polyamine, B) a polymeric wax inhibitor, and C) an organic solvent.

Claims

1. A wax inhibitor composition comprising A) a reaction product prepared by reaction of i) a carboxylic acid containing an optionally substituted cycloaliphatic hydrocarbyl residue with ii) an alkylene polyamine, B) a polymeric wax inhibitor, and C) an organic solvent.

2. The wax inhibitor composition according to claim 1, wherein the reaction product of the carboxylic acid containing an optionally substituted cycloaliphatic hydrocarbyl residue (i) and the alkylene polyamine (ii) is an amidoamine of the general formula (1)
R.sup.1—C(═O)—NR.sup.2—(CH.sub.2).sub.o—[NR.sup.3—(CH.sub.2).sub.m].sub.p—NR.sup.4R.sup.5  (1) wherein R.sup.1 is an optionally substituted hydrocarbyl residue having 5 to 70 carbon atoms which contains at least one cyclic structural unit, R.sup.2, R.sup.3 are, independently from each other, selected from the group consisting of hydrogen and a hydrocarbyl residue having 1 to 20 carbon atoms, R.sup.4 is hydrogen, or a hydrocarbyl residue having 1 to 20 carbon atoms, R.sup.5 is, independently from R.sup.4, selected from the group consisting of hydrogen, an optionally substituted hydrocarbyl residue having 1 to 20 carbon atoms, and an acyl group having the structure —C(═O)—R.sup.1, with the proviso that R.sup.4 and R.sup.5 together may form a 5- or 6-membered ring, o is an integer from 2 to 5, m is an integer from 2 to 5, and p is 0 or an integer from 1 to 10.

3. The wax inhibitor composition according to claim 1, wherein the reaction product of the carboxylic acid containing a cycloaliphatic structural unit (i) and the alkylene polyamine (ii) is an imidazoline of the general formula (2): ##STR00009## wherein R.sup.1 is an optionally substituted hydrocarbyl residue having 5 to 70 carbon atoms which contains at least one cyclic structural unit, R.sup.2, R.sup.3 are, independently from each other, selected from the group consisting of hydrogen and a hydrocarbyl residue having 1 to 20 carbon atoms, R.sup.4 is hydrogen, or a hydrocarbyl residue having 1 to 20 carbon atoms, R.sup.5 is, independently from R.sup.4, selected from the group consisting of hydrogen, an optionally substituted hydrocarbyl residue having 1 to 20 carbon atoms, and an acyl group having the structure —C(═O)—R.sup.1, with the proviso that R.sup.4 and R.sup.5 together may form a 5- or 6-membered ring, m is an integer from 2 to 5, and q is 0 or an integer between 1 and 9.

4. The wax inhibitor composition according to claim 1, wherein the reaction product of the carboxylic acid containing an optionally substituted cycloaliphatic hydrocarbyl residue (i) and the alkylene polyamine (ii) contains an amidoamine of the general formula (1) and an imidazoline of the general formula (2).

5. The wax inhibitor composition according to claim 4, wherein the ratio between amidoamine of the general formula (1) and an imidazoline of the general formula (2) is between 50:1 and 1:20.

6. The wax inhibitor composition according to claim 1, wherein the carboxylic acid containing a cycloaliphatic structural unit (i) has from 7 to 70 carbon atoms.

7. The wax inhibitor composition according to claim 1, wherein the carboxylic acid (i) used for the preparation of the reaction product (A) is a naphthenic acid.

8. The wax inhibitor composition according to claim 1, wherein the carboxylic acid (i) used for the preparation of the reaction product (A) is a resin acid.

9. The wax inhibitor composition according to claim 1, wherein a major amount of the carboxylic acid containing a cycloaliphatic structural unit (i) is reacted in admixture with a minor amount of a linear carboxylic acid to give co-additive (A).

10. The wax inhibitor composition according to claim 1, wherein the alkylene polyamine (ii) has from 2 to 20 car carbon atoms.

11. The wax inhibitor composition according to claim 1, wherein the alkylene polyamine (ii) contains from 2 to 10 nitrogen atoms.

12. The wax inhibitor composition according to claim 1, wherein the polymeric wax inhibitor (B) is selected from the group consisting of a) copolymers of ethylene with ethylenically unsaturated esters, ethers and/or C.sub.3 to C.sub.30-alkenes, b) homo- or copolymers of ethylenically unsaturated carboxylic acids, bearing C.sub.12-C.sub.50-alkyl radicals bound via ester, amide and/or imide groups, c) ethylene copolymers grafted with ethylenically unsaturated esters and/or ethers, and d) condensation products of alkyl substituted phenols with aldehydes and/or ketones.

13. The wax inhibitor composition according to claim 1, wherein the polymeric wax inhibitor (B) is a mixture of two or more different polymeric wax inhibitors.

14. The wax inhibitor composition according to claim 1, wherein the portion of reaction product (A) is between 1 and 50% by weight based on the combined masses of (A) and (B).

15. The wax inhibitor composition according to claim 1, wherein the portion of reaction product (A) is between 1 and 20% by weight based on the combined masses of (A) and (B).

16. The wax inhibitor composition according to claim 1, wherein the portion of polymeric wax inhibitor (B) is between 50 and 99% by weight based on the combined mass of (A) and (B).

17. The wax inhibitor composition according to claim 1, wherein the organic solvent (C) comprises a hydrocarbon or a hydrocarbon mixture.

18. The wax inhibitor composition claim 1, wherein the organic solvent (C) is an aliphatic hydrocarbon, a cycloaliphatic hydrocarbon, an aromatic hydrocarbon, an alkyl aromatic hydrocarbon, or a mixture thereof.

19. The wax inhibitor composition according to claim 1, wherein the organic solvent (C) has a flashpoint above 60° C.

20. (canceled)

21. A method to reduce the viscosity of a polymeric wax inhibitor (B) comprising the mixing of the polymeric wax inhibitor (B) with a reaction product (A) obtainable by reaction of a carboxylic acid containing an optionally substituted cycloaliphatic hydrocarbyl residue (i) with an alkylene polyamine (ii), wherein (A) and/or (B) are dissolved or dispersed in an organic solvent (C).

22. A method for improving the cold flow properties of a paraffin-containing hydrocarbon fluid wherein the method comprises admixing the paraffin-containing hydrocarbon fluid with a wax inhibitor composition, wherein the wax inhibitor composition comprises A) a reaction product prepared by reaction of i) a carboxylic acid containing an optionally substituted cycloaliphatic hydrocarbyl residue with ii) an alkylene polyamine, B) a polymeric wax inhibitor, and C) an organic solvent.

23. The method according to claim 22, wherein the paraffin-containing hydrocarbon fluid is a crude oil, residual oil, bunker oil or a heavy fuel oil.

24. The method according to claim 22, wherein the wax inhibitor composition acts as a pour point depressant.

25. The method according to claim 22, wherein the amount of the wax inhibitor composition added to the paraffin-containing hydrocarbon fluid is between 50 and 3000 ppm based on the paraffin-containing hydrocarbon fluid.

26. The method according to claim 22, wherein the wax inhibitor composition is injected into a crude oil pipeline.

27. The method according to claim 22, wherein the wax inhibitor composition is injected into a production well.

28. A composition comprising a paraffin-containing hydrocarbon fluid and a wax inhibitor composition, wherein the wax inhibitor composition comprises A) a reaction product prepared by reaction of i) a carboxylic acid containing an optionally substituted cycloaliphatic hydrocarbyl residue with ii) an alkylene polyamine, B) a polymeric wax inhibitor, and C) an organic solvent.

29. The composition according to claim 28, wherein the paraffin-containing hydrocarbon fluid is crude oil, residual oil, bunker oil or heavy fuel oil.

Description

EXAMPLES

[0185] The reactants used for preparation of the condensation products (A) were of technical grades. The molar amounts of carboxylic acid and amine given in table 1 were calculated from the acid number of the carboxylic acid and the amine number of the amine, both determined by potentiometric titration with a base respectively with an acid. The reaction products were characterized by IR spectroscopy: while an imidazoline shows a strong absorption band at 1605 cm.sup.−1, the amidoamine shows the absorption band at 1645 cm.sup.−1. The polymeric wax inhibitors were commercially available products. The molecular weight of EVA copolymers was measured as melt flow index (MFI.sub.190) according to ISO 1133 at a temperature of 190° C. and with a weight of 2.16 kg applied. Organic solvents used were technical grades.

TABLE-US-00001 TABLE 1 List of components used Reaction products of carboxylic acid with alkylene polyamine (A) A1 Reaction product of naphthenic acid (acid number 225 mg KOH/g) with an equimolar amount of diethylene triamine (DETA), prepared by heating the reactants for 6 hours to 160° C. in Solvent Naphtha. The product was characterized to be anamidoamine. A2 Reaction product of rosin acid (acid number 174 mg KOH/g) with an equimolar amount of diethylene triamine (DETA); prepared by heating the reactants for 6 hours to 155° C. in Solvent Naphtha. The product was characterized to be an amidoamine. A3 Reaction product of naphthenic acid (acid number 225 mg KOH/g) with an equimolar amount of triethylene tetramine (TETA), prepared by heating the reactants for 6 hours to 160° C. in Solvent Naphtha. The product was characterized to be an amidoamine. A4 Reaction product of equimolar amounts of naphthenic acid (acid number 225 mg KOH/g) and diethylene triamine (DETA), prepared by heating the reactants for 6 hours to 250° C. The obtained product was characterized to be an imidazoline. A5 Reaction product of rape seed oil with three molar equivalents of diethylene (comp.) triamine, prepared by heating the reactants for 6 hours to 255° C. under vacuum. The obtained product was characterized to contain predominantly imidazoline. A6 Reaction product of rapeseed oil with three equivalents of diethylene triamine (comp.) (DETA), prepared by heating the reactants for 6 hours to 155° C.C. The obtained was characterized to be an amidoamine. Polymeric wax inhibitors (B) B1 EVA copolymer having a vinyl acetate content of 28 wt.-% and a MFI.sub.190 of 7 g/10 min, grafted with behenyl acrylate in a weight ratio of 1:3. B2 EVA copolymer having a vinyl acetate content of 22 wt.-% and a MFI.sub.190 of 40 g/10 min, grafted with stearyl acrylate in a weight ratio of 1:4. B3 Copolymer of maleic anhydride with C.sub.20/24-α-olefin, esterified with behenyl alcohol; having an acid number of 38 mg KOH/g and a mean molecular weight Mw of 10.000 g/mol B4 Copolymer of maleic anhydride with C.sub.20/24-α-olefin, esterified with behenyl alcohol; having an acid number of 9 mg KOH/g and a mean molecular weight of 11.500 g/mol B5 Copolymer of maleic anhydride with C.sub.20-α-olefin, imidized with stearyl amine; having a mean molecular weight of 8.500 g/mol B6 EVA copolymer having a vinyl acetate content of 28 wt.-% and a MFI.sub.190 of 24 g/10 min B7 Poly(stearylacrylate), Mw 100.000 Dalton, measured per GPC against poly(styrene) standards Organic solvents (C) SN Solvent Naphtha; mixture of aromatic hydrocarbons having carbon numbers predominantly in the range of C.sub.9 through C.sub.11 and boiling in the range of from 177° C. to 216° C. Xyl xylene, mixture of isomers (technical grade)

[0186] From the components listed in table 1 wax inhibitor compositions were prepared with the proportions given in table 2. The percentages given for components A and B refer to the amounts of active ingredient. The final active content was adjusted with Solvent Naphtha or xylene. The pour point of the compositions was measured according to ASTM D5853 but with pour point readings made in increments of 1° C.

TABLE-US-00002 TABLE 2 Wax inhibitor compositions and their pour point Composition A B C Pour Point WI 01  4.5% A1 30.0% B1 65.5% SN +10° C. WI 02 (comp.) — 30.0% B1 70.0% SN +18° C. WI 03 10.0% A2 20.0% B2 70.0% SN +11° C. WI 04 (comp.) — 20.0% B2 80.0% SN +14° C. WI 05  4.5% A1 33.5% B3 62.0% SN +12° C. WI 06 22.0% A1 33.5% B3 44.5% SN  +7° C. WI 07 (comp.) — 33.5% B3 66.5% SN +15° C. WI 08  2.2% A1 36.7% B1 61.1% Xyl +16° C. WI 09  4.5% A1 36.7% B1 58.8% Xyl +14° C. WI 10 (comp.) — 36.7% B1 63.3% Xyl +21° C. WI 11  4.5% A1 20.0% B3 75.5% SN  −3° C. WI 12 (comp.) — 20.0% B3 80.0% SN +10° C. WI 13 (comp.)  4.5% A5 20.0% B3 75.5% SN  +2° C. WI 14 (comp.)  4.5% A6 20.0% B3 75.5% SN  +6° C. WI 15  4.4% A1 18.3% B5 77.3% SN −10° C. WI 16 (comp.) — 18.3% B5 81.7% SN  −8° C. WI 17 (comp.)  4.4% A5 18.3% B5 77.3% SN  −8° C. WI 18  4.5% A1 23.5% B3 68.2% SN   6° C.  8.3% B5 WI 19 (comp.) — 23.5% B3 72.7% SN  13° C.  8.3% B5 WI 20  4.0% A2  4.5% B6 93.4% SN −12° C. WI 21 (comp.) —  4.5% B6 97.8% SN  −9° C. WI 22  9.0% A3 20.0% B7 71.0% Xyl  +5° C. WI 23 (comp.) — 20.0% B7 80.0% Xyl  +7° C. WI 24  4.5% A4 40.0% B1 39.0% Xyl +16° C. 16.5% B7 WI 25 (comp.) — 40.0% B1 43.5% Xyl +21° C. 16.5% B7 WI 26 (comp.)  4.5% A6 40.0% B1 43.5% Xyl +18° C. 16.5% B7

[0187] The viscosity of the compositions was measured according to DIN 53019 (Brookfield) with a Haake Rheo Stress 600 in a Z40DIN Ti beaker having a volume of 70 ml, applying a shear rate of 10 s.sup.−1 and a cooling rate of 0.5° C./min. Table 3 gives the temperature at which the sample exceeds a viscosity of 1.000 mPas during this cooling protocol. For comparison, some additional viscosity values are listed in the table.

TABLE-US-00003 TABLE 3 Viscosity of wax inhibitors compositions at different temperatures wax inhibitor example composition viscosity temperature  1 WI 03 1,000 mPas  +8° C.  2 (comp.) WI 04 (comp.) 1,000 mPas +11° C.  3 WI 11 1,000 mPas  −4° C.  4 WI 11   20 mPas  +4° C.  5 (comp.) WI 12 (comp.) 1,000 mPas  +4° C.  6 WI 20 1,000 mPas  −6° C.  7 (comp.) WI 21 (comp.) 1,000 mPas  −7° C.  8 WI 15   40 mPas  −7° C.  9 WI 15 1,000 mPas <−15° C.  10 (comp.) WI 16 (comp.) 1,000 mPas  −7° C. 11 (comp.) WI 17 (comp.) 1,000 mPas  −9° C. 12 WI 18 1,000 m Pas  +8° C. 13 (comp.) WI 19 (comp.) 1,000 m Pas  +4° C. 14 WI 20 1,000 m Pas  −6° C. 15 (comp.) WI 21 (comp.) 1,000 m Pas  −7° C. 16 WI 22 1,000 m Pas  +3° C. 17 (comp.) WI 23 (comp.) 1,000 m Pas  +5° C.

[0188] The pour point reduction of wax inhibitor compositions according to table 2 in hydrocarbon fluids was tested in two crude oils. The characterization of the crude oils according to the SARA analysis according to IP 469 is given in table 4; the pour point results measured upon additivation of these oils with wax inhibitor compositions according to table 2 are given in tables 5 and 6. For comparison, A3 was tested upon dilution with xylene as a 9 wt.-% active solution.

TABLE-US-00004 TABLE 4 Characterization of crude oils crude oil A crude oil B S(aturates) 56% 71% A(romatics) 22% 15% R(esins)  7%  4% A(spalthenes) 15% 10% Pour Point 27° C. 27° C.

TABLE-US-00005 TABLE 5 Pour point reduction in crude oil 1 wax inhibitor Example composition dosage rate pour point 18 none 0 27° C. 19 WI 01 1,000 ppm  9° C. 20 (comp.) WI 02 (comp.) 1,000 ppm 12° C. 21 (comp.) A1   100 ppm 27° C. 22 WI 20 1,200 ppm  6° C. 23 (comp.) WI 21 (comp.) 1,200 ppm 12° C. 24 WI 24 1,000 ppm  6° C. 25 (comp.) WI 25 1,000 ppm  9° C. 26 (comp.) WI 26 1,000 ppm 12° C.

TABLE-US-00006 TABLE 6 Pour point reduction in crude oil 2 wax inhibitor Example composition dosage rate pour point 27 none 0 27° C. 28 WI 01 1,000 ppm 11° C. 29 (comp.) WI 02 (comp.) 1,000 ppm 12° C. 30 WI 22 1,200 ppm 12° C. 31 (comp.) WI 23 (comp.) 1,200 ppm 15° C. 32 (comp.) A3 (9% in Xyl) 1,200 ppm 27° C.

[0189] Far assessment at solubility on the wax inhibitor composition (additive) in a hydrocarbon fluid 5.000 ppm at a composition according ta table 2 was doped via a syringe into 100 ml at diesel in a cylindrical beaker with a height of 20 cm. The dissolution behavior was rated visually according ta the grading given in table 7. The results obtained with different wax inhibitors according ta table 2 are given in table 8.

TABLE-US-00007 TABLE 7 Rating of dissolving behavior grading visual observation 1 the additive dissolves on its way down the liquid but it does not reach the bottom of the cylinder. 2 part of the additive sinks to the bottom of the cylinder and dissolves upon gentle shaking. 3 the additive sinks to the bottom of the cylinder and requires shaking to dissolve.

TABLE-US-00008 TABLE 8 Dissolution behavior of wax inhibitor compositions wax inhibitor example composition temperature grading 33 WI 01 22° C. 1 34 WI 02 22° C. 3 (comp.) (comp.) 35 WI 03 22° C. 1 36 WI 04 22° C. 3 (comp.) (comp.) 37 WI 06 20° C. 1 38 WI 07 20° C. 3 (comp.) (comp.) 39 WI 24 25° C. 1 40 WI 25 25° C. 2 (comp.) (comp.)