METHOD AND USE

Abstract

A diesel fuel composition comprising as an additive an ester compound which is the reaction product of an optionally substituted polycarboxylic acid or an anhydride thereof and a polyhydric alcohol of formula H(OR).sub.nOH, wherein R is an optionally substituted alkylene group and n is at least 1.

Claims

1. A diesel fuel composition comprising as an additive an ester compound which is the reaction product of an optionally substituted polycarboxylic acid or an anhydride thereof and a polyhydric alcohol of formula H(OR).sub.nOH, wherein R is an optionally substituted alkylene group and n is at least 1.

2. A method of combatting deposits in a diesel engine, the method comprising combusting in the engine a diesel fuel composition comprising as an additive the reaction product of an optionally substituted polycarboxylic acid or an anhydride thereof and a polyhydric alcohol of formula H(OR).sub.nOH, wherein R is an optionally substituted alkylene group and n is at least 1.

3. (canceled)

4. The composition according to claim 1 wherein the optionally substituted polycarboxylic acid or anhydride thereof is a hydrocarbyl substituted succinic acid or a hydrocarbyl substituted succinic anhydride.

5. The composition according to claim 1 wherein each R is ethylene or propylene and n is from 1 to 20.

6. The composition according to claim 1 wherein the polycarboxylic acid or anhydride thereof includes an optionally substituted alkyl or alkenyl group having 6 to 100 carbon atoms.

7. The composition according to claim 1 wherein the optionally substituted polycarboxylic acid or hydrocarbyl substituted anhydride and alcohol of formula H(OR).sub.nOH are reacted in a ratio of from 1.5:1 to 1:1.5.

8. The composition according to claim 1 wherein the additive includes compounds having the formula (C1) or (C2): ##STR00008##

9. The composition according to claim 1 wherein the additive comprises the reaction product of a succinic acid or anhydride of formula (A3) or (A4): ##STR00009## and an alcohol of formula H(OR).sub.nOH; wherein R.sup.1 is an alkyl or alkenyl group having 6 to 36 carbon atoms or a polyisobutenyl group having a number average molecular weight of from 200 to 1300; wherein the alcohol of formula H(OR).sub.nOH is selected from the group consisting of: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, trehalose, sorbitol, glycerol, pentaerythritol, trimethylolpropane, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and a polyethylene or polypropylene glycol having a number average molecular weight of 300 to 1200.

10. The composition according to claim 1 wherein the additive comprises the reaction product of a succinic acid or anhydride having a C.sub.20 to C.sub.24 alkyl or alkenyl substituent and an alcohol selected from the group consisting of: 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, tripropylene glycol and polypropylene glycols having a number average molecular weight of from 300 to 600.

11. The composition according to claim 1 wherein the additive includes compounds having the formula (E): ##STR00010##

12. The composition according to claim 1 wherein the diesel engine is a modern diesel engine having a high pressure fuel system.

13. The method according to claim 2 which achieves keep clean performance.

14. The method according to claim 2 which achieves clean up performance.

15. The method according to claim 2 wherein the deposits are injector deposits.

16. The method according to claim 15 wherein the deposits are internal diesel injector deposits.

17. The composition according to claim 1 wherein the diesel fuel composition comprises less than 50 ppm sulphur by weight.

18. The composition according to claim 1 wherein the diesel fuel composition comprises biodiesel.

19. The composition according to claim 1 wherein the diesel fuel composition comprises one or more further detergents selected from the group consisting of: (i) a quaternary ammonium salt additive; (ii) the product of a Mannich reaction between an aldehyde, an amine and an optionally substituted phenol; (iii) the reaction product of a carboxylic acid-derived acylating agent and an amine; (iv) the reaction product of a carboxylic acid-derived acylating agent and hydrazine; (v) a salt formed by the reaction of a carboxylic acid with di-n-butylamine or tri-n-butylamine; (vi) the reaction product of a hydrocarbyl-substituted dicarboxylic acid or anhydride and an amine compound or salt which product comprises at least one amino triazole group; and (vii) a substituted polyaromatic detergent additive.

20. The composition according to claim 1 wherein the diesel fuel composition comprises a mixture of two or more ester additives.

21. The method according to claim 2 which achieves an improvement in performance of one or more of: a reduction in power loss of the engine; a reduction in external diesel injector deposits; a reduction in internal diesel injector deposits; an improvement in fuel economy; a reduction in fuel filter deposits; a reduction in emissions; or an increase in maintenance intervals.

22. The method according to claim 21 which provides an improvement in performance in modern diesel engines having a high pressure fuel system and provides an improvement in performance in traditional diesel engines.

23. (canceled)

24. The composition according to claim which further comprises one or more further additives selected from the group consisting of: lubricity improvers, corrosion inhibitors and cold flow improvers.

25. (canceled)

Description

[0357] FIG. 1 shows the power output of the engine when running the fuel composition comprising additive Al over the test period.

[0358] FIG. 2 shows the power output of the engine when running the fuel composition comprising additive A16 over the test period.

EXAMPLE 6

[0359] The ability of additives of the invention to remove Internal Diesel Injector Deposits (IDIDs) may be measured according to he test method CEC F-110-16, available from the Co-ordinating European Council. The test uses the PSA DW10C engine. The engine characteristics as follows:

TABLE-US-00006 Design: Four cylinders in line, overhead camshaft, variable geometry turbocharger with EGR Capacity: 1997 cm.sup.3 Combustion chamber: Four valves, bowl in piston, direct injection Power: 120 kW @ 3750 rpm Torque: 340 Nm @ 2000 rpm Injection system: Common rail with solenoid type injectors Delphi Injection System Emissions control: Conforms to Euro V limit values when combined with exhaust gas post-treatment system.

[0360] The test fuel (RF06) is dosed with 0.5 mg/kg Na in the form of Sodium Naphthenate +10 mg/kg Dodecyl Succinic Acid (DDSA).

[0361] The test procedure consists of main run cycles followed by soak periods, before cold starts are carried out.

[0362] The main running cycle consist of two speed and load set points, repeated for 6hrs, as seen below.

TABLE-US-00007 Speed Torque Duration Step (rpm) (N .Math. m) (s) 1 3750 280 1470 1 - Ramp .fwdarw.2 30 2 1000 10 270 2 - Ramp .fwdarw.1 30

[0363] The ramp times of 30 seconds are included in the duration of each step.

[0364] During the main run, parameters including, Throttle pedal position, ECU fault codes, Injector balance coefficient and Engine stalls are observed and recorded.

[0365] The engine is then left to soak at ambient temperature for 8 hrs.

[0366] After the soak period the engine is re-started. The starter is operated for 5 seconds; if the engine fails to start the engine is left for 60 seconds before a further attempt. A maximum of 5 attempts are allowed.

[0367] If the engine starts the engine is allowed to idle for 5 minutes. Individual exhaust temperatures are monitored and the maximum Temperature Delta is recorded. An increased variation in Cylinder-to-Cylinder exhaust temperatures is a good indication that injectors are suffering from IDID. Causing them to either open slowly or stay open to long.

[0368] An example below of all exhaust temperatures with <30 C. deviation, indicating no sticking caused by IDID.

[0369] The complete test comprises of 6 Cold Starts, although the Zero hour Cold Start does not form part of the Merit Rating and 56 hr Main run cycles, giving a total of 30 hrs engine running time.

[0370] The recorded data is inputted into the Merit Rating Chart. This allows a Rating to be produced for the test. Maximum rating of 10 shows no issues with the running or operability of the engine for the duration of the test.

[0371] An example below:

EXAMPLE 7

[0372] The ability of additives of the invention to clean up IDIDs was assessed according to a modification of the DW10C test described in example 6.

[0373] The In-House Clean-Up Method developed starts by running the engine using reference diesel (RF06) dosed with 0.5 mg/kg Na+10 mg/Kg DDSA until an exhaust temperature Delta of >50 C. is observed on the Cold Start. This has repeatedly been seen on the 3.sup.rd Cold Start which follows the second main run, 12 hrs total engine run time.

[0374] Once the increased Exhaust temperature Delta is observed, the engine fuel supply is swapped to reference diesel, dosed with 0.5 mg/kg Na (as sodium naphthenate) +10 mg/kg DDSA +the Candidate sample. The fuel is flushed through to the engine and allowed to commence with the next Main run.

[0375] The ability of the Candidate additive to prevent any further increase in deposits or to remove the deposits can then be determined as the test continues.

[0376] A diesel fuel composition comprising additive A1 (53 ppm active) was tested according to the test method outlined above. A final De-Merit rating of 8.5 was achieved. The full results are provided in table 3.

TABLE-US-00008 TABLE 3 Cold start Starting Exhaust temperature consistency Number of Exhaust Temperature Attempts Max Cyl, Cold Start Maximum (1 = Maximum Devistion start Y/N Merits first start) Deduction Merits Merits ( C.) Deduction Merits #0 Y 10.2 #1 Y 5 1 0 5 5 30.4 3 2 #2 Y 5 1 0 5 5 51.8 5 0 #3 Y 5 1 0 5 5 28.1 0 5 #4 Y 5 1 0 5 5 30.5 33 2 #5 Y 5 1 0 5 5 29.9 0 5 Total merits 25 14 Main run Operability Max Pedal Number of Position at Max Inject. Main Maximum ECU Fault Stall 1000 rpm/ Balancing run Merits resets Deduction (Y/N) Deduction 10 N .Math. m (%) Deduction Coeff. (rpm) Deduction Merits #1 5 0 0 N 0 17.4 0 14.9 0 5 #2 5 0 0 N 0 14.4 0 15.2 0 5 #3 5 0 0 N 0 15.3 0 15.6 0 5 #4 5 0 0 N 0 16.1 0 15.4 0 5 #5 5 0 0 N 0 17.0 0 15.2 0 5 25 Global Rating - Summary (Merit/10) 8.5333 indicates data missing or illegible when filed

[0377] A diesel fuel composition comprising additive A16 (50 ppm active) was also tested according to the method of example 6. A final demerit rating of 7.47 was achieved. The full results are provided in table 4.

TABLE-US-00009 TABLE 4 Cold start Exhaust temperature consistency Starting Exhaust Number of Temperature Attempts Max Cyl. Cold Start Maximum (1 = Maximum Deviation Start Y/N Merits first start) Deduction Merits Merits ( C.) Deduction Merits #0 not rated #1 Y 5 1 0 5 5 32.3 3 2 #2 Y 5 1 0 5 5 139.3 5 0 #3 Y 5 1 0 5 5 59.1 5 0 #4 Y 5 1 0 5 5 49.9 3 2 #5 Y 5 1 0 5 5 47.7 3 2 Total merits 25 6 Main run Operability Max Pedal Number of Position at Max Inject. Main Maximum ECU Fault Stall 1000 rpm/ Balancing run Merits resets Deduction (Y/N) Deduction 10 N .Math. m (%) Deduction Coeff. (rpm) Deduction Merits #1 5 0 0 N 0 15.9 0 11.8 0 5 #2 5 0 0 N 0 18.7 0 11.8 0 5 #3 5 0 0 N 0 19.9 0 10.4 0 5 #4 5 0 0 N 0 19.7 0 10.6 0 5 #5 5 0 0 N 0 19.1 0 10.4 0 5 25 Global Rating - Summary (Merit/10) 7.466667

[0378] A diesel fuel composition comprising additive A10 (50 ppm active) was also tested according to the method of example 6. A final demerit rating of 8.67 was achieved. The full results are provided in table 5.

TABLE-US-00010 TABLE 5 Cold start Exhaust temperature consistency Starting Exhaust Number of Temperature Attempts Max Cyl. Cold Start Maximum (1 = Maximum Deviation Start Y/N Merits first start) Deduction Merits Merits ( C.) Deduction Merits #0 not rated #1 Y 5 1 0 5 5 32.6 3 2 #2 Y 5 1 0 5 5 162.8 5 0 #3 Y 5 2 1 4 5 17.8 0 5 #4 Y 5 1 0 5 5 19.7 0 5 #5 Y 5 1 0 5 5 23.4 0 5 Total 24 17 Main run Operability Max Pedal Number of Position Max Inject. Main Maximum ECU Fault Stall at 1000 rpm/ Balancing run Merits resets Deduction (Y/N) Deduction 10 N .Math. m (%) Deduction Coeff. (rpm) Deduction Merits #1 5 0 0 N 0 14.4 0 11.6 0 5 #2 5 0 0 N 0 17.8 0 10.7 0 5 #3 5 1 1 N 0 18.2 0 10.8 0 4 #4 5 0 0 N 0 16.9 0 9.8 0 5 #5 5 0 0 N 0 16.1 0 9.7 0 5 24 Global Rating - Summary (Merit/10) 8.666667

EXAMPLE 8

[0379] The effectiveness of the additives of the invention in older traditional diesel engine types maybe assessed using a standard industry testCEC test method No. CEC F-23-A-01.

[0380] This test measures injector nozzle coking using a Peugeot XUD9 A/L Engine and provides a means of discriminating between fuels of different injector nozzle coking propensity. Nozzle coking is the result of carbon deposits forming between the injector needle and the needle seat. Deposition of the carbon deposit is due to exposure of the injector needle and seat to combustion gases, potentially causing undesirable variations in engine performance.

[0381] The Peugeot XUD9 A/L engine is a 4 cylinder indirect injection Diesel engine of 1.9 litre swept volume, obtained from Peugeot Citroen Motors specifically for the CEC PF023 method.

[0382] The test engine is fitted with cleaned injectors utilising unflatted injector needles. The airflow at various needle lift positions have been measured on a flow rig prior to test. The engine is operated for a period of 10 hours under cyclic conditions.

TABLE-US-00011 Time Speed Torque Stage (secs) (rpm) (Nm) 1 30 1200 30 10 2 2 60 3000 30 50 2 3 60 1300 30 35 2 4 120 1850 30 50 2

[0383] The propensity of the fuel to promote deposit formation on the fuel injectors is determined by measuring the injector nozzle airflow again at the end of test, and comparing these values to those before test. The results are expressed in terms of percentage airflow reduction at various needle lift positions for all nozzles. The average value of the airflow reduction at 0.1 mm needle lift of all four nozzles is deemed the level of injector coking for a given fuel.