USE AND METHOD FOR REDUCING DEPOSITS IN A DIESEL ENGINE

Abstract

The use of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I):

##STR00001##

or an anhydride thereof; and/or of a polymer prepared from components (i) and (ii); as an additive in a diesel fuel composition to reduce the impact of deposits in an EGR system and/or the post combustion system of a diesel engine when combusting said diesel fuel composition.

Claims

1. The use of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I): ##STR00010## or an anhydride thereof; and/or of a polymer prepared from components (i) and (ii); as an additive in a diesel fuel composition to reduce the impact of deposits in an EGR system and/or the post combustion system of a diesel engine when combusting said diesel fuel composition.

2. A method of reducing the impact of deposits in an EGR system and/or the post combustion system of a diesel engine, the method comprising combusting in the engine a diesel fuel composition comprising as an additive a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I): ##STR00011## or an anhydride thereof; and/or a polymer prepared from components (i) and (ii).

3. The method of claim 2, which reduces the formation of deposits in the exhaust gas recirculation system of a diesel engine.

4. The method of claim 2, which reduces the formation of deposits in the post combustion system of a diesel engine.

5. The method of claim 2, wherein the dicarboxylic acid or anhydride thereof is selected from itaconic acid, itaconic anhydride, 2-methylene glutaric acid, 2-methylene glutaric anhydride, 2-methylene adipic acid, 2-methylene adipic anhydride and isomers and/or mixtures thereof.

6. The method of claim 2, wherein the dicarboxylic acid is itaconic acid.

7. The method of claim 2, wherein the alcohol is selected from: alkanols of formula CH.sub.3(CH.sub.2).sub.xOH or an isomer thereof wherein x is from 4 to 23; alkenyl alcohols in which n is 0; glycol ethers in which n is not 0.

8. The method of claim 2, wherein the alcohol is selected from an an alcohol of formula R.sup.1OH wherein R.sup.1 is a alkyl group having 8 to 30 carbon atoms; an alcohol of formula R.sup.1OH wherein R.sup.1 is an alkenyl group having 8 to 30 carbon atoms; and an alcohol of formula H(OR).sub.nOR.sup.1 wherein n is from 1 to 24, R is ethylene, propylene or isopropylene, and R.sup.1 is an unsubstituted alkyl group having 8 to 30, carbon atoms.

9. The method of claim 2, wherein the alcohol is selected from hexanol, octanol, nonanol, decanol, dodecanol, tetradecanol, cetyl alcohol, stearyl alcohol, 2-ethyl-1-butanol, 2-ethyl-1-hexanol, 2-ethyl-1-heptanol, 2-propylheptanol, 2-ethyl-1-decanol, 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol, isotridecanol, cyclohexanol, cyclooctanol, benzyl alcohol, citronellol, oleyl alcohol, 9-decen-1-ol, cis-3-hexen-1-ol, trans-2-hexen-1-ol, 5-hexen-1-ol, 6-methyl-5-hepten-2-ol, 1-octen-3-ol, trans-2-octen-1-ol, 10-undecen-1-ol and compounds of formula CH.sub.3(CH.sub.2).sub.xO(CH.sub.2CH(CH.sub.3)O).sub.yH or an isomer thereof wherein x is from 10 to 15, and y is from 10 to 20.

10. The method of claim 2, wherein the polycarboxylic acid compound and the alcohol are reacted in a molar ratio of from 2:1 to 1:2.

11. The method of claim 2, wherein the additive is the direct reaction product of (i) an alcohol and (ii) a compound of formula (I) or an anhydride thereof.

12. The method of claim 2, wherein the additive is a polymer prepared from components (i) and (ii).

13. The method according to claim 12, wherein the additive is a polymer of formula (II): ##STR00012## wherein n is at least 2, x may be 0 or a positive integer, y may be 0 or a positive integer and each R is independently hydrogen or an optionally substituted hydrocarbyl group provided that at least 10% of all R groups are not hydrogen.

14. The method according to claim 13, wherein the polymeric additive is prepared by polymerising the reaction product of a dicarboxylic acid of formula (I) and an alcohol.

15. The method according to claim 13, wherein n is from 10 to 200.

16. The method of claim 2, wherein the polymeric additive of formula (II) is the polymerised reaction product of itaconic acid or an anhydride thereof and 2-ethylhexanol wherein the polymer has a weight average molecular weight of from 2000 to 50000.

17. The method of claim 2, wherein the additive is present in the fuel in an amount of from 10 to 200 ppm.

18. The method of claim 2, wherein the exhaust gas recirculation system is a high pressure exhaust gas recirculation system, wherein the high pressure EGR system is either a stand-alone high pressure EGR system or is part of a hybrid or a dedicated EGR system.

19. The method of claim 2, which reduces deposits in the post combustion system of a diesel engine having a pressure in excess of 1350 bar.

20. The method of claim 2, which reduces the formation of deposits in a cooler of the EGR system, preferably by at least 10%.

21. The method of claim 2, which reduces the formation of deposits on the turbocharger of the post combustion system.

22. This method of claim 2, which reduces the formation of deposits on the diesel oxidation catalyst of the post combustion system.

23. The method of claim 2, which reduces the formation of deposits on the diesel particulate filter of the post combustion system.

24. The method of claim 2, which reduces the accumulation of soot in the diesel particulate filter.

25. The method of claim 2, which reduces the formation of deposits on the selective catalytic reduction unit of the post combustion system.

26. The method of claim 2, which reduces the formation of deposits on the ammonia oxidation catalyst of the post combustion system.

27. The method of claim 2, which reduces the formation deposits on sensors within the post combustion system.

28. The method of claim 2, which reduces the formation of deposits in one more components of the post combustion system by at least 5%.

29. The method of claim 2, wherein the diesel engine is an off road engine, for example a marine, rail or stationary engine.

30. The method of claim 2, which provides one or more benefits selected from: an increase in power generation; an increase in torque; an increase in fuel economy; a reduction in emissions; a reduction in combustion chamber deposits; an acceleration improvement; driveability improvements; a reduction in cold start issues; lower soot formation; mitigation of lubricant degradation and/or performance loss; a reduction in diesel exhaust fluid and consumption e.g. urea consumption; reduction in wear on all post combustion components (including but not limited to the turbo charger, oxidation catalyst, DPF, SCR CAT, sensors, and injectors within the post combustion system); increased longevity of exhaust components; and the protection of intake components downstream of the EGR.

Description

EXAMPLE 1

[0300] Additive A1, an additive of the present invention was prepared as follows:

[0301] A 500 mL, 3-neck round bottom flask was fitted with a magnetic stirrer, condenser, Dean-Stark apparatus, gas inlet/outlet, stirrer hotplate and oil bath. Oleyl alcohol (206.19 g, 0.768 mol), itaconic acid (100 g, 0.768 mol) and p-toluenesulfonic acid (0.439 g, 2.30 mmol) were combined and heated to 165 C. (internal temperature). The reaction mass was held at 165 C. for 6 hours and water was removed. The reaction mass became homogenous and a colour change to orange was observed. After cooling to room temperature, the reaction mass was transferred to a 2 L separating funnel and toluene (270 mL) was added. The toluene-diluted reaction mass was washed with 1:1 water-methanol (1540 mL), the organic phase separated and volatiles removed on the rotary evaporator, providing a viscous orange liquid (257.6 g).

[0302] The acid value of Additive A1 was 2.0 mmolH.sup.+/g.

EXAMPLE 2

[0303] Additive A2, an additive of the present invention was prepared as follows:

[0304] A 100 mL, 3-neck round bottom flask was fitted with a magnetic stirrer, condenser and stirrer hotplate. Citronellol (20 g, 0.128 mol), itaconic acid (16.52 g, 0.127 mol) and p-toluenesulfonic acid (0.073 g, 0.38 mmol) were combined and heated to 160 C. (internal temperature) for 6 hours. After cooling to room temperature, a sample (15 g) of the total reaction mass was taken and dissolved in toluene (15 mL). The toluene solution was washed with 1:1 water-methanol (130 mL), the organic phase separated and volatiles removed on the rotary evaporator, providing a viscous orange liquid (13.6 g).

[0305] The acid value of Additive A2 was 2.7 mmolH.sup.+/g.

EXAMPLE 3

[0306] Additive A3, an additive of the present invention was prepared using a method analogous to the methods described in examples 1 and 2.

[0307] The acid value of Additive A3 was 2.4 mmolH.sup.+/g.

EXAMPLE 4

[0308] Additive A4, a polymeric additive of the invention was prepared as follows:

[0309] To a 1 L reactor charged with 2-ethylhexanol (250 g, 1.918 moles) was added toluene (215.7 g) and heated to 90 C. To the stirred liquid was added itaconic acid (250 g, 1.921 moles) and p-toluenesulfonic acid (3.31 g). The reaction was heated towards 120 C., whilst removing water by distillation over 7 hours. The products where cooled to room temperature and unreacted itaconic and p-toluenesulfonic acid removed by filtration and washing with water. The toluene was removed on a rotary evaporator to leave a yellow/orange liquid (2-ethylhexyl itaconate, 412.9 g)

[0310] To a 250 ml reactor was charged 2-ethylhexyl itaconate (120 g) was added cyclohexane (51.43 g) and the reactor contents sparged with Nitrogen for 1 hour whilst heating to 80 C. Trigonox 25-C75 (0.685 g, 0.5 wt, %, tert-Butyl peroxypivalate) was added and the reaction was mixed at 80 C. for 1 hour before adding further Trigonox 25-C75 (0.685 g) and heating for a further 3 hours at 80 C. The cyclohexane was removed on a rotary evaporator and Aromatic 150 (69.7 g) added to leave a clear amber viscous liquid (184.4 g, Mw 10932, acid value of 2.4 mmolH.sup.+/g).

EXAMPLE 5

[0311] Additive A5, a polymeric additive of the invention was prepared as follows:

Step 1Esterification to 2-Ethylhexyl Itaconate

[0312] A clean 1 L oil jacketed reactor with overhead stirrer, was purged with nitrogen and charged with 2-ethylhexanol (300.91 g, 2.31 moles), aromatic 150 (236.32 g) and stirred. Itaconic acid (250.51 g, 1.925 moles) and para-toluene sulphonic acid (1.54 g, 0.2 wt. %) were added and the reaction heated to 120 C. Water was distilled from the reaction as an azeotrope with A150 for 4 hours. The reaction mixture was heated to 80 C. and washed with water (2150 ml) by stirring for 10 minutes and allowing to separate for 1 hour and draining the lower aqueous. The residual water was removed under vacuum at 80 C. for 1 hour.

Step 2Polymerisation to Poly 2-Ethylhexyl Itaconate

[0313] The reaction mixture from step 1 was heated to 72 C. and purged with nitrogen.

[0314] Trigonox 25-C75 (62 g) was added over 5 hours, with an addition each hour. The reaction was heated for a further 6 hours before diluting with further aromatic A150 (207.42 g) to leave a pale amber, viscous clear liquid (836.29 g)additive A5comprising 55 wt % of active agent content.

EXAMPLE 6ENGINE TESTING

[0315] Engine testing was carried out as described below to assess the performance of the additives of the present invention in the reduction of deposits in the post combustion system of diesel engines and in the reduction of deposits in the exhaust gas recirculation system of a diesel engine.

Engine Details

[0316] A Euro 6 compliant 2.0 litre, HSDI engine was connected to a test automation system and test bed fitted with an engine dynamometer. The engine was controlled by an ECU supplied by the engine manufacturer. The engine had had over 1100 h of use prior to the first test. The engine oil was changed prior to performing the first test.

Modifications/Test Setup

[0317] 1. No SCR Catalyst or associated components were present in the exhaust system. [0318] 2. High pressure EGR cooler is artificially controlled to 40 C. for the duration of the test.

[0319] The base fuel was an RF-06-03 diesel fuel (Haltermann Carless, UK) having the following specification:

TABLE-US-00001 Feature Units Results Minimum Maximum Method Density 15 C. kg/m.sup.3 836.0 833.0 837.0 ASTM D4052 Marker (Red) Pass VISUAL Cetane Number 53.9 52.0 54.0 ASTM D613 I.B.PI. C. 214.3 ASTM D86 10% v/v Recovered at C. 232.0 ASTM D86 50% v/v Recovered at C. 275.5 245.0 ASTM D86 90% v/v Recovered at C. 330.2 ASTM D86 95% v/v Recovered at C. 348.0 345.0 350.0 ASTM D86 F.B.PI. C. 356.2 370.0 ASTM D86 Aromatics by FIA % (V/V) 19.8 Corrected for ASTM D1319 Olefins by FIA % (V/V) 5.5 Flash Point, Pensky Closed C. 92.0 55.0 ASTM D93 Sulphur Content mg/kg <3.0 10.0 ASTM D5453 Viscosity at 40 C. mm2/s 3.062 2.300 3.300 ASTM D445 Cloud Point C. 18 ASTM D2500 CFPP C. 20 15 EN 116 Lubricity (WSD 1.4) at 60 C. m 180 400 ISO 12156-1 Carbon Residue (on 10% Dist. Res) % (m/m) <0.10 0.20 ASTM D4530 Ash % (m/m) <0.001 0.010 ASTM D482 FAME Content: None Detected Pass EN 14078 Polycyclic Aromatic Hydrocarbons % (m/m) 5.8 3.0 6.0 EN 12916 Total Aromatic Hydrocarbons % (m/m) 22.2 EN 12916 Water Content mg/kg 50 200 IP 438 Water & Sediment % (V/V) <0.010 ASTM D2709 Strong Acid Number mg 0 KOH/g 0.02 ASTM D974 Oxidation Stability mg <0.1 per 2.5 ASTM D2274 100 ml Copper Corrosion, 3 hrs at 100 C. 1B ASTM D130 Oxygen Content % (m/m) <0.04 ELEMENTAL Elemental Analysis Carbon Content % (m/m) 86.89 ASTM D5291 ASTM D5291 Hydrogen Content % (m/m) 13.11 ASTM D5291 ASTM D5291 Carbon Weight Fraction 0.8889 CALCULATION Calculation C/H Mass Ratio 6.63 CALCULATION Calculation Atomic H/C Ratio 1.7979 CALCULATION Calculation Atomic O/C Ratio <0.0003 CALCULATION Calculation Gross Heat of Combustion MJ/kg 45.72 IP 12 IP 12 Net Heat of Combustion MJ/kg 42.94 IP 12 IP 12 Net Heat of Combustion btu/lb 18460 CALCULATION Calculation

Test Additives, Treat Rate:

[0320] The example additive A5 was dosed at 100 ppm into the base diesel fuel described above to provide test fuel 1. Therefore test fuel 1 contained 55 ppm of the active agent (poly 2-ethylhexyl itaconate).

Method of Soot Deposition Measurement (DPF & EGR Soot Weight)

[0321] The quantity of soot deposited in the EGR cooler was established by weighing the component before and after each test.

[0322] The quantity of soot deposited in the DPF was established by weighing both components before and after each test.

[0323] The EGR cooler is thoroughly cleaned using tap water sprayed at high pressure through the cooler matrix. This cleaning process is performed until no more deposit can be seen in the cooler matrix with the naked eye.

[0324] The EGR cooler was then placed into an oven, pre-heated to 185 C., affixed to a set of scales. The weight measurement was taken as an average is taken over 15 minutes, once the scales had stabilised. This weighing process is repeated at the end of the test. The variance between the weight measured before and after the test represents the change in mass due to soot deposition.

[0325] Prior to the initial weighing, the DPF is passively regenerated on the test bed to remove any residual soot. Once the regeneration is complete, the DPF is placed into an oven, pre-heated to 185 C., affixed to a set of scales. The weight measurement was taken as an average over 15 minutes, once the scales had stabilised. This weighing process is repeated at the end of the test. The variance between the weight measured before and after the test represents the change in mass due to soot deposition.

Test Procedure

[0326] [D] EGR Cleaned and weighed [0327] [D] DPF+Slave EGR Installation [0328] Engine Start+Warm-Up [0329] Passive DPF Regeneration by varying the engine speed and load until the regeneration is complete. The differential pressure across the is used to monitor the regeneration progress. [0330] Engine Stop [0331] Change to test fuel [0332] [C] DPF+Slave EGR Removal [0333] [C] DPF Start-of-Test (SOT) Weighing [0334] [C] DPF+[C] EGR Installation [0335] Engine Start+Warm-Up [0336] 8-Hour Steady-State Test Cycle [0337] 1200 RPM [0338] 60 Nm [0339] Engine Stop [0340] [D] DPF Removal and End-of-Test (EOT) Weighing [0341] [D] EGR Removal and EGR End of Test Weighing

[0342] [C] indicates a clean component

[0343] [D] indicates a fouled component

RESULTS

TABLE-US-00002 Treat EGR cooler DPF Soot rate Soot Weight Weight Test fuel Additive (ppm) [g] [g] Base fuel 1.59 36.35 1 A5 100 1.24 33.00

[0344] These results demonstrate that the use of the additives described herein in a diesel fuel composition may provide a significant reduction in deposits in an exhaust gas recirculation system of a diesel engine combusting said fuel.

[0345] These results also demonstrate that the use of the additives described herein in a diesel fuel composition may provide a significant reduction in deposits in the post combustion system of a diesel engine combusting said fuel, specifically a reduction in the soot deposited on the diesel particulate filter of the post combustion system.