CYCLIC QUATERNARY AMMONIUM SALTS AS FUEL OR LUBRICANT ADDITIVES

Abstract

Quaternary ammonium salts of formula: wherein each of R.sup.1 and R.sup.2 is independently selected from an optionally substituted alkyl, alkenyl or aryl group having less than 8 carbon atoms, R together with N forms an aliphatic or aromatic heterocycle having less than 12 carbons atoms and R.sup.5 is hydrogen or an optionally substituted hydrocarhyl group. The use of these compounds as fuel or lubricant additives, especially as diesel fuel additives,

Claims

1. A quaternary ammonium salt of formula: ##STR00018## wherein each of R.sup.1 and R.sup.2 is independently selected from an optionally substituted alkyl, alkenyl or aryl group having less than 8 carbon atoms, R together with N forms an aliphatic or aromatic heterocycle having less than 12 carbon atoms and R.sup.5 is hydrogen or an optionally substituted hydrocarbyl group.

2. The quaternary ammonium salt according to claim 1 which is prepared by reacting a cyclic tertiary amine of formula R??NR.sup.1 with a quaternising agent selected from: (i) an ester of formula R.sup.5COOR.sup.2; (ii) a carbonate compound of formula R.sup.4OCOOR.sup.2 and then a carboxylic acid of formula R.sup.5COOH; and (iii) an epoxide having less than 8 carbon atoms and a carboxylic acid of formula R.sup.5COOH; wherein R.sup.4 is an optionally substituted hydrocarbyl group.

3. The quaternary ammonium salt according to claim 2 wherein the quaternising agent is (ii) a carbonate compound of formula R.sup.4OCOOR.sup.2 and then a carboxylic acid of formula R.sup.5COOH.

4. A quaternary ammonium salt which is the reaction product of: (a) a cyclic tertiary amine having less than 19 carbon atoms; (b) an epoxide having less than 8 carbon atoms; and (c) a carboxylic acid of formula R.sup.5COOH; wherein R.sup.5 is hydrogen or an optionally substituted hydrocarbyl group.

5. A method of preparing a quaternary ammonium salt, the method comprising reacting (a) a cyclic tertiary amine having less than 19 carbon atoms with (b) an epoxide in the presence of (c) a carboxylic acid of formula R.sup.5COOH; wherein R.sup.5 is hydrogen or an optionally substituted hydrocarbyl group.

6. The method according to claim 5 wherein component (a) comprises an amine of formula R??NR.sup.1 in which R.sup.1 is an optionally substituted hydrocarbyl group and R and N together form a heterocycle having less than 12 carbon atoms.

7. An additive composition comprising one or more quaternary ammonium. compounds according to claim 1 and a diluent or carrier.

8. A lubricating composition comprising as an additive one or more quaternary ammonium compounds according to claim 1 and a lubricant.

9. A fuel composition comprising as an additive one or more quaternary ammonium compounds according to claim 1 and a fuel.

10. The fuel composition according to claim 9 wherein the fuel is diesel fuel,

11. The fuel composition according to claim 10 which comprises one or more further detergents selected from the group consisting of: (i) an additional quaternary ammonium salt additive which is not a quatemary ammonium compound of claim 1; (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 &carboxylic-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.

12. The fuel composition according to claim 9 wherein the fuel is gasoline fuel.

13. The fuel composition according to claim 12 which comprises one or more gasoline detergents selected from the group consisting of: (p) hydrocarbyl-substituted polyoxyalkylene amines or polyetheramines; (q) acylated nitrogen compounds which are the reaction product of a carboxylic acid-derived acylating agent and an amine; (r) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms; (s) Mannich base additives comprising nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine; (t) aromatic esters of a polyalkylphenoxyalkanol; (u) an additional quaternary ammonium salt additive which is not a quaternary ammonium compound of claim 1; and (v) tertiary hydrocarbyl amines having a maximum of 30 carbon atoms.

14. A method of preparing a fuel composition according to claim 9, the method comprising adding the quaternary ammonium salt additive to the fuel after the fuel has left the distribution terminal.

15. A method of improving the performance of an engine, the method comprising combusting in said engine a fuel composition comprising as an additive one or more quaternary ammonium compounds according to claim 1.

16. The method according to claim 15 wherein the engine is a gasoline engine and the fuel is a gasoline fuel.

17. The method according to claim 15 wherein the engine is a diesel engine having a fuel injection system which comprises a high pressure fuel injection (H H) system with fuel pressures greater than 1350 bar.

18. The method according to claim 17 wherein improvement in performance is achieved by combating deposits in the engine,

19. The method according to claim 18 which combats internal diesel injector deposits.

20. The method according to claim 18 which combats external diesel injector deposits, including injector nozzle deposits and injector tip deposits,

21. The method according to claim 18 which combats fuel filter deposits.

22. The method according to claim 17 wherein the improvement in performance is a power gain compared to when combusting an unadditised base fuel and with clean injectors.

23. (canceled)

24. The method according to claim 15 to achieve keep clean performance.

25. The method according to claim 15 to achieve clean up performance.

26. The method according to claim 15 wherein the improvement in performance is achieved by combating deposits in the engine.

27. The method according to claim 15 wherein the improvement in performance is a power gain compared to when combusting an unadditized base fuel and with clean injectors.

Description

EXAMPLE 1

[0387] Additive A19, Bis (1,1-dimethylpyrrolidin-1-ium) octadecenyl succinate was prepared as follows:

[0388] A sample of octadenyl succinic acid was prepared by hydrolysis of a xylene solution of a commercial sample of the corresponding anhydride before removing volatiles by rotary evaporation leaving a cream-coloured solid. The acid value was determined, by wet analysis, to be 5.27 mMol/g (calc. 5.32).

[0389] N-methyl pyrrolidine (2.865 g, 33.7 mMol), dimethyl carbonate (12.298 g, 136.6 mMol) and methanol (10 cm3) were charged to a tube and heated, with stirring, for one hour at 130? C., under autogeneous pressure. The formation of a methyl carbonate salt was confirmed by FTIR (characteristic absorbance at 1651 cm.sup.?1).

[0390] The solution of 1,1-dimethylpyrrolidin-1-ium methyl carbonate was transferred to a round-bottom flask. Octadecenyl succinic acid (6.282 g, 33.1 mMol of acidity) was added. On stirring and warming (oil bath, 45? C.) the solids dissolved, with gas evolution. After 60 minutes gas evolution had ceased. The solution was taken to dryness on a rotary evaporator (2 mBar, 90? C.), forming orange-brown waxy solids which were dissolved, with warming, in an equal mass of 2-ethyl hexanol. Mass balances and FTIR spectra were in accord with substantially complete formation of a carboxylate salt (absorbances at about 1575 and 1378 cm.sup.?1)

EXAMPLE 2

[0391] Additive A21, Bis (N,N-dimethyl imidazolium) octadecenyl succinate was prepared as follows:

[0392] N-methyl imidazole (2.544 g, 31 mMol), dimethyl carbonate (10.96 g, 122 mMol) and methanol (12.5 cm.sup.3) were charged to a tube and heated, with stirring, under autogeneous pressure, at 160? C. for three hours. The formation of a methyl carbonate salt was confirmed by FTIR (absorbance at 1645 cm.sup.?1).

[0393] Material from the tube was transferred to a round-bottom flask and reacted with a single equivalent (acid value basis, 0.5 molar equivalents) of octadecenyl succinic acid, as set out above. The material was stripped to dryness in the rotary evaporator (6 mBar, 90? C.). Mass balance was consistent with formation of the desired product in good yield. The material was dissolved, with strong heating, in an equal mass of 2-ethyl hexanol. The FTIR spectrum was consistent with formulation as the proposed carboxylate salt, with characteristic absorbances at 1569 and 1379 cm.sup.-1.

EXAMPLE 3

[0394] Additives A16, A17 and A18 were each prepared as a 50% w/w solution in 2-ethyl hexanol as follows:

[0395] The succinic acid suspended in 2-ethylhexan-1-ol was placed in a boiling tube. One or two equivalents of cyclic tertiary amine and one or two equivalents of epoxide were added and the reaction heated at 95? C. for 6 hours. The product was confirmed via FTIR spectra.

[0396] The further compounds using the following acids, amines and epoxides:

TABLE-US-00001 Amine added Epoxide added Additive Acid (molar equiv) (molar equiv) A16 Octadecenylsuccinic Methyl Pyrollidine 1,2-epoxybutane acid (2) (2) A17 Octadecenylsuccinic Methyl Pyrollidine Iso propyl acid (2) glycidyl ether (2) A18 Octadecenylsuccinic Methyl Imidazole Iso propyl acid (2) glycidyl ether (2) A22 C30+ alpha Methyl Pyrollidine 1,2-epoxybutane olefin succinic (1) (1) acid

[0397] The C30+ alpha olefin succinic acid is the reaction product of a terminal alkene consisting mainly of molecules having at least 30 carbon atoms and maleic anhydride. The alkene is available commercially from Chevron Phillips Chemical Company under the trade mark AlphaPlus? C30+.

EXAMPLE 4

[0398] Diesel fuel compositions were prepared comprising the additives listed in Table 1, added to aliquots all drawn from a common batch of RFO6 base fuel.

TABLE-US-00002 TABLE 1 Fuel Composition Additive (ppm active) Comparative C 105 1 A16 105 2 A17 105 3 A18 105 4 A19 105 5 A21 105 6 A22 105

[0399] Additive C is a comparative low molecular weight succinimide detergent additive, that was prepared as follows:

[0400] Polyisobutylene succinic anhydride with a Mn of 360((442g) was charged to a reactor followed by solvent Shellso1150 (442g). 1 equivalent of tetraethylene pentamine (243g) was added and the mixture stirred at 175C for 3 hours whilst distilling off the water in a dean and stark condenser. The product was then discharged from the reactor.

[0401] Table 2 below shows the specification for RFO6 base fuel.

TABLE-US-00003 TABLE 2 Limits Property Units Min Max Method Cetane Number 52.0 54.0 EN ISO 5165 Density at 15? C. kg/m.sup.3 833 837 EN ISO 3675 Distillation 50% v/v Point ? C. 245 95% v/v Point ? C. 345 350 FBP ? C. 370 Flash Point ? C. 55 EN 22719 Cold Filter Plugging ? C. ?5 EN 116 Point Viscosity at 40? C. mm.sup.2/sec 2.3 3.3 EN ISO 3104 Polycyclic Aromatic % m/m 3.0 6.0 IP 391 Hydrocarbons Sulphur Content mg/kg 10 ASTM D 5453 Copper Corrosion 1 EN ISO 2160 Conradson Carbon % m/m 0.2 EN ISO 10370 Residue on 10% Dist. Residue Ash Content % m/m 0.01 EN ISO 6245 Water Content % m/m 0.02 EN ISO 12937 Neutralisation mg 0.02 ASTM D 974 (Strong Acid) KOH/g Number Oxidation Stability mg/mL 0.025 EN ISO 12205 HFRR (WSD1,4) ?m 400 CEC F-06-A-96 Fatty Acid prohibited Methyl Ester

EXAMPLE 5

[0402] Each of the fuel compositions prepared in example 4 was tested using Jet Fuel Thermal Oxidation Test (JFTOT) equipment. In this test 800 ml of fuel is flowed over an aluminium tube heated to 260? C. at a pressure of approximately 540 psi (3.72?10.sup.6 Pa). The test duration is 2.5 hours. At the end of test the aluminium tube is removed and the thickness of deposit compared to the comparative fuel.

[0403] The results are shown in table 2.

TABLE-US-00004 Deposit Fuel Thickness Composition (nm) Comparative 377 1 60 2 43 3 105 4 49 5 43 6 21

EXAMPLE 6

[0404] The performance of fuel compositions of the present invention in modern diesel engines having a high pressure fuel system may be tested according to the CECF-98-08 DW 10 method.

[0405] The engine of the injector fouling test is the PSA DW1OBTED4. In summary, the engine characteristics are:

[0406] Design: Four cylinders in line, overhead camshaft, turbocharged with EGR

[0407] Capacity: 1998 cm.sup.3

[0408] Combustion chamber: Four valves, bowl in piston, wall guided direct injection

[0409] Power: 100 kW at 4000 rpm

[0410] Torque: 320 Nm at 2000 rpm

[0411] Injection system: Common rail with piezo electronically controlled 6-hole injectors.

[0412] Max. pressure: 1600 bar (1.6?10.sup.8 Pa). Proprietary design by SIEMENS VDO Emissions control: Conforms with Euro IV limit values when combined with exhaust gas post-treatment system (DPF)

[0413] This engine was chosen as a design representative of the modern European high-speed direct injection diesel engine capable of conforming to present and future European emissions requirements. The common rail injection system uses a highly efficient nozzle design with rounded inlet edges and conical spray holes for optimal hydraulic flow. This type of nozzle, when combined with high fuel pressure has allowed advances to be achieved in combustion efficiency, reduced noise and reduced fuel consumption, but are sensitive to influences that can disturb the fuel flow, such as deposit formation in the spray holes. The presence of these deposits causes a significant loss of engine power and increased raw emissions.

[0414] The test is run with a future injector design representative of anticipated Euro V injector technology.

[0415] It is considered necessary to establish a reliable baseline of injector condition before beginning fouling tests, so a sixteen hour running-in schedule for the test injectors is specified, using non-fouling reference fuel.

[0416] Full details of the CEC F-98-08 test method can be obtained from the CEC. The coking cycle is summarised below.

[0417] 1. A warm up cycle (12 minutes) according to the following regime:

TABLE-US-00005 Duration Engine Speed Torque Step (minutes) (rpm) (Nm) 1 2 idle <5 2 3 2000 50 3 4 3500 75 4 3 4000 100

[0418] 2. 8 hrs of engine operation consisting of 8 repeats of the following cycle

TABLE-US-00006 Boost Air Duration Engine Speed Load Torque After IC Step (minutes) (rpm) (%) (Nm) (? C.) 1 2 1750 (20) 62 45 2 7 3000 (60) 173 50 3 2 1750 (20) 62 45 4 7 3500 (80) 212 50 5 2 1750 (20) 62 45 6 10 4000 100 * 50 7 2 1250 (10) 20 43 8 7 3000 100 * 50 9 2 1250 (10) 20 43 10 10 2000 100 * 50 11 2 1250 (10) 20 43 12 7 4000 100 * 50 * for expected range see CEC method CEC-F-98-08

[0419] 3. Cool down to idle in 60 seconds and idle for 10 seconds

[0420] 4. 4 hrs soak period

[0421] The standard CEC F-98-08 test method consists of 32 hours engine operation corresponding to 4 repeats of steps 1-3 above, and 3 repeats of step 4. ie 56 hours total test time excluding warm ups and cool downs.

EXAMPLE 7

[0422] The effectiveness of the fuel compositions of the present invention in older engine types may be assessed using a standard industry testCEC test method No. CEC F-23-A-01.

[0423] 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.

[0424] 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.

[0425] 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-00007 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

[0426] 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.

EXAMPLE 8

[0427] In Europe the Co-ordinating European Council for the development of performance tests for transportation fuels, lubricants and other fluids (the industry body known as CEC), has developed a new test for additives for modern diesel engines such as HSDI engines. The CEC F-110-xx .sup.1 test is used to assess whether diesel fuel is suitable for use in engines meeting new European Union emissions regulations known as the Euro 5 regulations. The test is based on a Peugeot DW10 engine using Euro 5 injectors, and is commonly referred to as DW10C test. This test measures the effects of deposits on the injectors specific to IDID's with respect to injector sticking. Test procedure still in draft format and final CEC issue number not yet available.

[0428] In this test thermocouples are positioned in the engine to enable the exhaust temperature of each cylinder to be measured. This, in conjunction with other measured parameters, allows injector sticking to be tested.

[0429] The engine of the injector fouling test is the PSA DW10CTED4/E5. In summary, the engine characteristics are:

[0430] Design: Four cylinders in line, overhead camshaft, turbocharged with EGR

[0431] Capacity: 1997 cm.sup.3

[0432] Combustion chamber: Four valves, bowl in piston, wall guided direct injection

[0433] Power: 120 kW at 3750 rpm

[0434] Torque: 340 Nm at 2000 rpm

[0435] Injection system: Common rail with piezo electronically controlled 6-hole injectors.

[0436] Max. pressure: 1600 bar (1.6?10.sup.8 Pa). Proprietary design by Delphi

[0437] Emissions control: Conforms with Euro V limit values when combined with exhaust gas post-treatment system (DPF)

[0438] This engine was chosen as a design representative of the modern European high-speed direct injection diesel engine capable of conforming to present and future European emissions requirements. The common rail injection system uses a highly efficient nozzle design with rounded inlet edges and conical spray holes for optimal hydraulic flow. This type of nozzle, when combined with high fuel pressure has allowed advances to be achieved in combustion efficiency, reduced noise and reduced fuel consumption, but are sensitive to influences that can cause injector sticking.

[0439] The test is run with current injector design conforming to Euro V injector technology.

[0440] Full details of the CEC F-110-xx test method can be obtained from the CEC. The test cycle is summarised below.

[0441] 1. Warm-Up stages:

TABLE-US-00008 Duration Engine Speed Torque Step (minutes) (rpm) (Nm) 1 2 1000 10 2 3 2000 50 3 4 3500 75 4 3 3750 100

[0442] 2. Main Run

TABLE-US-00009 Duration Engine Speed Torque Step (seconds) (rpm) (Nm) 1 1470 1750 280 1 - Ramp .fwdarw. 2 270 3000 2 - Ramp .fwdarw. 1 30

[0443] The test procedure consists of alternating sequences of soak periods followed by cold starts preceding main run cycles of engine operation. There are 5 main runs and 6 cold starts.

[0444] If the engine should fail to start or stall during engine operation and cannot be restarted the test is aborted.

[0445] During the test ECU parameters are recorded together with exhaust temperatures to evaluate any indication of injector sticking. These parameters contribute to an overall demerit rating at the conclusion of the test.