Corrosion inhibitors for fuels and lubricants

Abstract

The present invention relates to novel uses of corrosion inhibitors in fuels and lubricants.

Claims

1. A method of inhibiting corrosion in a fuel system, the method comprising: passing a fuel through a fuel system, wherein the fuel comprises: at least one of an alkali metal, an alkaline earth metal, and zinc in an amount of at least 0.1 ppm by weight; and a polymer having a statistical average of at least 4 acid groups per polymer chain, a ratio of carbon atoms per acid group of 7 to 35, and an acid number of 80 to 320 mg KOH/g, determined by potentiographic titration with 0.5 molar aqueous hydrochloric acid after heating in 0.5 molar ethanolic potassium hydroxide solution for three hours.

2. The method according to claim 1, wherein the fuel comprises at least one of sodium, zinc, magnesium and calcium.

3. The method according to claim 1, wherein the acid groups are carboxyl groups.

4. The method according to claim 1, wherein the polymer comprises up to 50 acid groups per polymer chain.

5. The method according to claim 1, wherein the polymer comprises not more than 5 functional groups other than oxygen-containing functional groups and nitrogen-containing functional groups per polymer chain.

6. The method according to claim 1, wherein the polymer comprises not more than 3 oxygen-containing functional groups per polymer chain other than carbonate groups, ether groups or ester groups.

7. The method according to claim 1, wherein the polymer comprises not more than 20 ether groups per polymer chain.

8. The method according to claim 1, wherein the polymer comprises not more than 50 carbonate groups or ester groups per polymer chain.

9. The method according to claim 1, wherein the polymer has a weight-average molecular weight Mw of 0.5 to 20 kDa (determined by gel permeation chromatography with tetrahydrofuran and polystyrene as standard) and a polydispersity of 1 to 10.

10. The method according to claim 1, wherein the fuel system comprises an article that comprises at least one of iron, steel, and a nonferrous metal.

11. The method according to claim 1, wherein the fuel system comprises an article that comprises copper.

12. The method according to claim 1, wherein the fuel is a diesel fuel or gasoline fuel.

13. The method according to claim 1, wherein the polymer has a solubility in toluene at 20? C. of at least 0.5 g/100 mL.

14. A method of inhibiting corrosion in a diesel fuel system, the method comprising: passing a diesel fuel through a fuel system, wherein the diesel fuel comprises: at least one of an alkali metal, an alkaline earth metal, and zinc in an amount of at least 0.1 ppm by weight; a polymer having a statistical average of at least 4 acid groups per polymer chain, a ratio of carbon atoms per acid group of 7 to 35, and an acid number of 80 to 320 mg KOH/g, determined by potentiographic titration with 0.5 molar aqueous hydrochloric acid after heating in 0.5 molar ethanolic potassium hydroxide solution for three hours; and at least one additive selected from the group consisting of a detergent additive, a carrier oil, a cold flow improver, a lubricity improver, a corrosion inhibitor other than the polymer, a demulsifier, a dehazer, an antifoam, a cetane number improver, a combustion improver, an antioxidant, a stabilizer, an antistat, a metallocene, a metal deactivator, a dye and a solvent.

15. A method of inhibiting corrosion in a gasoline system, the method comprising: passing gasoline through a fuel system, wherein the gasoline comprises: at least one of an alkali metal, an alkaline earth metal, and zinc in an amount of at least 0.1 ppm by weight; a polymer having a statistical average of at least 4 acid groups per polymer chain, a ratio of carbon atoms per acid group of 7 to 35, and an acid number of 80 to 320 mg KOH/g, determined by potentiographic titration with 0.5 molar aqueous hydrochloric acid after heating in 0.5 molar ethanolic potassium hydroxide solution for three hours; and at least one additive selected from the group consisting of a lubricity improver, a corrosion inhibitor other than the polymer, a demulsifier, a dehazer, an antifoam, a combustion improver, an antioxidant, a stabilizer, an antistat, a metallocene, a metal deactivator, a dye, and a solvent.

Description

EXAMPLES

(1) GPC Analysis

(2) Unless stated otherwise, the mass-average molecular weight Mw and number-average molecular weight Mn of the polymers was measured by means of gel permeation chromatography (GPC). GPC separation was effected by means of two PLge Mixed B columns (Agilent) in tetrahydrofuran at 35? C. Calibration was effected by means of a narrow-distribution polystyrene standard (from PSS, Germany) having a molecular weight of 162-50 400 Da. Hexylbenzene was used as a marker for low molecular weight.

(3) Determination of Acid Number

(4) Determination of Efficacy Value

(5) 50 mL of 0.5 molar ethanolic KOH are heated in a 150 mL COD tube provided with an air cooler to 95? C. for three (3) hours. The air cooler is purged with 30 mL of ethanol and then the solution is potentiographically titrated with 0.5 molar aqueous hydrochloric acid (HCl).

(6) Determination of the Sample

(7) About 1 g of sample is weighed into a 150 mL COD tube and dissolved in 50 mL of 0.5 molar ethanolic KOH. The COD tube is provided with an air cooler and placed into a stirred block thermostat preheated to 95? C. After three (3) hours, the COD tube is removed from the heating block and rinsed with 30 mL of ethanol, and the solution is potentiographically titrated with 0.5 molar aqueous hydrochloric acid (HCl).

Preparation Examples

(8) General Procedure

(9) A reactor having an anchor stirrer was initially charged with the olefin or the mixture of olefins with or without solvent (as a bulk polymerization). The mixture was heated to the temperature specified under a nitrogen stream and while stirring. To this were added the free-radical initiator specified (optionally diluted in the same solvent) and molten maleic anhydride (1 equivalent based on olefin monomer). The reaction mixture was stirred at the same temperature for the reaction time specified and then cooled down. Subsequently, water was added (unless stated otherwise, 0.9 equivalent based on maleic anhydride) and the mixture was stirred either at 95? C. for 10-14 h or under pressure at 110? C. for 3 h.

Synthesis Example 1

(10) A 2 L glass reactor having an anchor stirrer was initially charged with a mixture of C.sub.20-C.sub.24 olefins (363.2 g, average molar mass 296 g/mol) and Solvesso 150 (231.5 g, DHC Solvent Chemie GmbH, Speldorf). The mixture was heated to 160? C. in a nitrogen stream and while stirring. To this were added, within 5 h, a solution of di-tert-butyl peroxide (29.6 g, from Akzo Nobel) in Solvesso 150 (260.5 g) and molten maleic anhydride (120.3 g). The reaction mixture was stirred at 160? C. for 1 h and then cooled to 95? C. At this temperature, water (19.9 g) was added within 3 h and then stirring was continued for 11 h.

(11) GPC (in THF) gave an Mn=1210 g/mol, Mw=2330 g/mol for the copolymer, which corresponds to a polydispersity of 1.9.

(12) The copolymer had a ratio of carbon atoms per acid group of 13; the acid number determined by the above method was 210.8 mg KOH/g.

Synthesis Example 2

(13) A 6 L metal reactor having an anchor stirrer was initially charged with a mixture of C.sub.20-C.sub.24 olefins (1743 g, average molar mass 296 g/mol) and Solvesso 150 (1297 g, DHC Solvent Chemie GmbH, Speldorf). The mixture was heated to 150? C. in a nitrogen stream and while stirring. To this were added, within 5 h, a solution of di-tert-butyl peroxide (118.4 g, from Akzo Nobel) in Solvesso 150 (1041 g) and molten maleic anhydride (577 g). The reaction mixture was stirred at 150? C. for 1 h and then cooled to 110? C. At this temperature, with an increase in pressure, water (95 g) was added and then stirring was continued for 3 h.

(14) GPC (in THF) gave an Mn=1420 g/mol, Mw=2500 g/mol for the copolymer, which corresponds to a polydispersity of 1.8.

(15) The copolymer had a ratio of carbon atoms per acid group of 13; the acid number determined by the above method was 210.8 mg KOH/g.

Synthesis Example 3

(16) A 6 L metal reactor having an anchor stirrer was initially charged with a mixture of C.sub.20-C.sub.24 olefins (1743 g, average molar mass 296 g/mol) and Solvesso 150 (1297 g, DHC Solvent Chemie GmbH, Speldorf). The mixture was heated to 150? C. in a nitrogen stream and while stirring. To this were added, within 5 h, a solution of di-tert-butyl peroxide (23.7 g, from Akzo Nobel) in Solvesso 150 (912 g) and molten maleic anhydride (577 g). The reaction mixture was stirred at 150? C. for 1 h and then cooled to 110? C. At this temperature, with an increase in pressure, water (95 g) was added and then stirring was continued for 3 h.

(17) GPC (in THF) gave an Mn=1500 g/mol, Mw=3200 g/mol for the copolymer, which corresponds to a polydispersity of 2.1.

(18) The copolymer had a ratio of carbon atoms per acid group of 13; the acid number determined by the above method was 210.8 mg KOH/g.

Use Examples

(19) The additive formulations specified in Table 2 were produced from the above synthesis examples by mixing with polyisobuteneamine (molar mass 1000), polypropylene glycol as carrier oil and solvent and dehazer, and used in the use examples (compositions in parts by weight).

(20) 1) Calcium Compatibility Test:

(21) 100 mL of motor oil (Shell Helix?, FIG. 1, far left beaker, with a Ca content of 1500 ppm, Mg content of 1100 ppm and Zn content of 1300 ppm) were heated to 70? C. in the beaker and then 1 mL of corrosion inhibitor was added. Should the solution still be clear, a further 1 mL of inhibitor is added. If the solution turns cloudy, the test is considered to have been failed (e.g. FIG. 1, right-hand beaker). FIG. 1 shows the oil to which copolymer according to synthesis example 1 (50% in Solvent Naphtha) has been added, which remains clear, in the middle. In the right-hand beaker, dimer fatty acid (dimeric oleic acid; CAS: 61788-89-4, 20% in Solvent Naphtha) was used. Distinctly visible turbidity is apparent.

(22) 2) Steel Corrosion Test to ASTM D 665 B

(23) a) The fuel used was conventional 95 octane EO gasoline fuel from Haltermann, which was additized with an additive package composed of polyisobuteneamine and carrier oil. The corrosion inhibitors specified in the table which follows were added to the formulation, which was subjected to a corrosion test to ASTM D 665 B.

(24) Dimer fatty acid (dimeric oleic acid; CAS: 61788-89-4, as corrosion inhibitor, 20% in Solvent Naphtha) was used as a comparison.

(25) TABLE-US-00001 Active corrosion Assessment Corrosion inhibitor content according to inhibitor [ppm] NACE Blank value - D Haltermann E0 (no additization) Blank value - E Haltermann E0 (with additization) Formulation 1 Dimer fatty acid 2 A Formulation 2 Synthesis 2.5 A example 1 Formulation 3 Synthesis 5 A example 1

(26) The assessment was made as follows:

(27) A 100% rust-free

(28) B++ 0.1% or less of the total surface area rusted

(29) B+ 0.1% to 5% of the total surface area rusted

(30) B 5% to 25% of the total surface area rusted

(31) C 25% to 50% of the total surface area rusted

(32) D 50% to 75% of the total surface area rusted

(33) E 75% to 100% of the total surface area rusted

(34) b) A further experiment was conducted analogously to a) but with an EO gasoline fuel KS-0001829 CEC DF-12-09.

(35) The results are as follows:

(36) TABLE-US-00002 Active corrosion Assessment Corrosion inhibitor content according to inhibitor [ppm] NACE Base value KS- E 0001829 (without additization) Formulation 13 Dimer fatty acid 2 A Formulation 14 Synthesis 2 A example 2 Formulation 1 Dimer fatty acid 2 A Formulation 7 Synthesis 2 B+ example 3 Formulation 11 Dimer fatty acid 2 C

(37) c) A further experiment was conducted analogously to a) but with a gasoline fuel KS-0001858 MIRO 95 OCTANE E10.

(38) The results are as follows:

(39) TABLE-US-00003 Active corrosion Assessment Corrosion inhibitor content according to inhibitor [ppm] NACE Base value KS- E 0001858 (without additization) Formulation 13 Dimer fatty acid 2 B++ Formulation 14 Synthesis 2 B+ example 2 Formulation 1 Dimer fatty acid 2 A Formulation 7 Synthesis 2 A example 3 Formulation 11 Dimer fatty acid 2 B+

(40) d) The test was conducted in accordance with standard ASTM D665 A (modified) with distilled water and ASTM D665 B (modified) with synthetic seawater in a mixture with diesel base fuel in accordance with EN590 B7, without performance additives. The modifications were that the temperature was 60? C. and the duration of the test was 4 hours.

(41) TABLE-US-00004 Assessment in the Assessment in the ASTM D665A test ASTM D665B test Additive (with distilled water) (with synthetic seawater) No additions B E 140 mg/kg of A B sample according to preparation example 1

(42) e) A further experiment was conducted according to ASTM D 665 B, in which a conventional 95 octane EO gasoline fuel was used and was additized with an additive package composed of polyisobuteneamine and carrier oil. Polyisobutenesuccinic acid (based on polyisobutene of molar mass 1000) and dimer fatty acid (dimeric oleic acid; CAS: 61788-89-4) were added to the formulation as a comparison and subjected to a corrosion test according to ASTM D 665 B.

(43) TABLE-US-00005 Dosage NACE [mg/kg] rating Base value E E0 RON 95 Dimer fatty acid 2 A/B* Polyisobutenesuccinic acid 2 C Polyisobutenesuccinic acid 8 B/C* *two tests

(44) f) A further experiment was conducted according to ASTM D 665 B, in which a conventional 95 octane EO gasoline fuel was used and was additized with an additive package composed of polyisobuteneamine (based on polyisobutene of molar mass 1000), dehazer and carrier oil. Dodecenylsuccinic acid (acid number 392 mg KOH/g) and dimer fatty acid (dimeric oleic acid; CAS: 61788-89-4) were added to the formulation as a comparison and subjected to a corrosion test according to ASTM D 665 B.

(45) TABLE-US-00006 Dosage NACE [mg/kg] rating* Base value D E0 RON 95 Dimer fatty acid 2 A/B+ Dodecenylsuccinic acid 3.2 A/B++ Dodecenylsuccinic acid 2.75 B++/B++ *two tests

(46) The dodecenylsuccinic acid-containing additive package showed a separation into phases on storage at room temperature, which shows that dodecenylsuccinic acid does not have adequate solubility in the additive package.

(47) 3) Copper Corrosion

(48) a) In Gasoline

(49) Copper coupons (dimensions 49?25?1.5 mm, punched in the middle) were carefully polished with a polishing machine having the appropriate polishing brush without firm pressure on both sides and on all edges. The polished coupons were rubbed well several times with xylene and acetone using a clean cloth, using rubber gloves. 200 mL of fuel were introduced into a 250 mL screw-top glass bottle. The coupon was secured with a thread and suspended in the fuel bottle. The thread was fixed by trapping it in the screw thread.

(50) Storage took place at room temperature (23? C.). After the first storage period (7 days) had elapsed, a sample was taken (20-30 mL), the glass bottle was closed again and the metal content was determined by means of atomic absorption spectroscopy. The storage was continued. After repeated sampling and dropping of liquid level, it was ensured that the copper coupon was fully covered by fuel.

(51) The results are listed in table 1.

(52) It is apparent from the results in table 1 that the compounds of the invention used, in the same dosage, have a lower tendency to leach copper out of wetted surfaces in fuels than the dimer fatty acid used as a comparison.

(53) b) In Diesel Fuel

(54) To study the corrosion characteristics of the sample from synthesis example 1 with respect to nonferrous metals, tests were conducted with zinc and copper wires.

(55) 80 mL of Aral B7 EN590 fuel were dispensed into each of four bottles, to two of which had been added 140 ppm of a sample from synthesis example 1. Degreased copper wire of length 20 cm and diameter 1 mm was positioned in one bottle with and one bottle without this sample. Analogously, degreased zinc wire of length 20 cm and diameter 1 mm was positioned in one bottle with and one bottle without this sample.

(56) The copper or zinc content of the original fuel was determined after storage at 40? C. for 6 weeks by means of atomic emission spectroscopy (ICP/OES).

(57) TABLE-US-00007 Fuel Fuel (no addition, 6 Fuel (140 ppm added, 6 (start) weeks at 40? C.) weeks at 40? C.) Zn content <1 <1 <1 [mg/kg] Cu content <1 4 <1 [mg/kg]

(58) It can be seen that the compounds of the invention have a corrosion-inhibiting effect on nonferrous metals, especially on copper.

(59) 4) PFI Engine Test DC M111E

(60) An engine test was conducted over 60 hours according to CEC F-020-98 with MIRO 95 octane E10 fuel, and the internal valve deposits (IVD) and total chamber deposits (TCD values) were determined.

(61) A TCD value of 4122 mg was found in keep-clean mode for the additized fuel without corrosion inhibitor, but a TCD value of 3940 mg for the additized fuel with corrosion inhibitor (formulation 10).

(62) In addition, an IVD value of 116 mg/valve was found for the unadditized fuel and, in keep-clean mode, an IVD value of 2 mg/valve for the additized fuel without corrosion inhibitor, but an IVD value of 1 mg/valve for the additized fuel with corrosion inhibitor (formulation 10).

(63) 5) Keep-Clean Test in a Gasoline Direct Injection Engine (DISI)

(64) A commercially available DISI (direct injection spark injection) engine (cylinder capacity 1.6 liters) was operated with an E10 gasoline fuel from MIRO (7% by volume of oxygen-containing components) at a speed of 4000 rpm for 50 hours.

(65) In the first run, the fuel did not comprise any additives. The FR value fluctuated between 0 and -1.

(66) In the second run, the fuel comprised 520 mg/kg of formulation 10. The FR value fluctuated between ?2 and ?3.

(67) In both runs, the FR value was determined. FR is a parameter which is generated by the engine control system in accordance with the injection of fuel into the combustion chamber. The formation of deposits is manifested by a rising FR value during a run. The more it grows, the more deposits have formed. If the FR value remains constant or decreases, the injector nozzle also remains clean. In neither run does the FR value rise, which indicates that the copolymer claimed does not have any adverse effect on injector cleanliness.

(68) TABLE-US-00008 TABLE 1 E0 fuel from E0 fuel from E0 fuel from E10 fuel E10 fuel E10 fuel 2)b) 2)b) 2)b) from 2)c) from 2)c) from 2)c) Duration Duration Duration Duration Duration Duration [days] [days] [days] [days] [days] [days] 7 14 28 7 14 28 Copper Copper Copper Copper Copper Copper Active component content content content content content content Active component mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg No additization <0.1 <0.1 0.4 0.7 Formulation 12 0.1 0.2 0.5 0.8 Formulation 1 Dimer fatty acid 2.0 0.2 0.4 0.8 0.9 1.7 3 Formulation 4 Synthesis 2.0 0.1 0.2 0.4 0.8 1.4 2.5 example 2 Formulation 5 Synthesis 4.0 0.2 0.3 0.6 1 1.7 3 example 2 Formulation 6 Synthesis 8.0 0.3 0.5 0.7 1.2 1.8 3 example 2 Formulation 7 Synthesis 2.0 0.1 0.3 0.5 0.9 1.4 2.7 example 3 Formulation 8 Synthesis 4.0 0.2 0.4 0.6 1.1 1.7 3 example 3 Formulation 9 Synthesis 8.0 0.3 0.5 0.8 1 1.8 2.8 example 3

(69) TABLE-US-00009 TABLE 2 Synthesis Synthesis Synthesis example 1 (50% example 2 (40% example 3 (40% Polyisobutene Dimer fatty in Solvent in Solvent in Solvent Solvent + Sum amine Carrier oil acid Naphtha) Naphtha) Naphtha) dehazer total Formulation 1 248 195 10 47 500 Formulation 2 248 195 5 47 495 Formulation 3 248 195 10 47 500 Formulation 4 248 195 5 47 495 Formulation 5 248 195 10 47 500 Formulation 6 248 195 20 47 510 Formulation 7 248 195 5 47 495 Formulation 8 10 47 500 Formulation 9 20 47 510 Formulation 248 195 30 47 520 10 Formulation 248 195 5 47 495 11 Formulation 248 195 47 490 12 Formulation 259 156 10 596 1021 13 Formulation 259 156 5 596 1016 14