QUATERNARY AMMONIUM COMPOUNDS AS FUEL OR LUBRICANT ADDITIVES

Abstract

A quaternary ammonium compound of formula (X):

##STR00001## wherein R.sup.0, R.sup.1, R.sup.2 and R.sup.3 is each individually an optionally substituted alkyl, alkenyl or aryl group and R includes an optionally substituted hydrocarbyl moiety having at least 5 carbon atoms.

Claims

1. A method of preparing a fuel composition, said method comprising: preparing a quaternary ammonium compound by reacting: (a) a tertiary amine of formula R.sup.1R.sup.2R.sup.3N with; (b) an epoxide; in the presence of (c) a monoester of a diacid including an optionally substituted hydrocarbyl moiety having at least 5 carbon atoms; wherein R.sup.1, R.sup.2 and R.sup.3 are each independently selected from an optionally substituted alkyl, alkenyl or aryl group; and mixing the quaternary ammonium compound into a fuel.

2. A method according to claim 1 wherein each of R.sup.1 and R.sup.2 is independently alkyl, alkenyl or aryl group having from 1 to 50 carbon atoms optionally substituted with one or more groups selected from halo (especially chloro and fluoro), hydroxy, alkoxy, keto, acyl, cyano, mercapto, alkylmercapto, dialkylamino, nitro, nitroso, and sulphoxy.

3. A method according to claim 1 wherein R.sup.3 is an alkyl or alkenyl group having from 1 to 50 carbon atoms optionally substituted with one or more substituents selected from halo (especially chloro and fluoro), hydroxy, alkoxy, keto, acyl, cyano, mercapto, alkylmercapto, amino, alkylamino, nitro, nitroso, sulphoxy, amido, alkyamido, imido and alkylimido.

4. A method according to claim 1 wherein R.sup.3 is an alkyl or alkenyl group optionally substituted with alkoxy or hydroxy groups.

5. A method according to claim 1 wherein each of R.sup.1 and R.sup.2 is an unsubstituted alkyl group or a hydroxy substituted alkyl group.

6. A method according to claim 1 wherein R.sup.3 is selected from: (x) an optionally substituted alkylene phenol moiety of formula (A) or (B) ##STR00031## wherein n is 0 to 4, preferably 1, R is an optionally substituted hydrocarbyl group, R is an optionally substituted alkyl, alkenyl or aryl group; and L is a linking group; (y) a succinimide moiety of formula: ##STR00032## wherein R is an optionally substituted hydrocarbyl group and L is a linking group; and (z) a polyisobutenyl group having a molecular weight of from 100 to 5000, preferably from 500 to 2000.

7. A method according to claim 1 wherein the quaternary ammonium compound has the formula (X): ##STR00033## wherein R.sup.0, R.sup.1, R.sup.2 and R.sup.3 is each individually an optionally substituted alkyl, alkenyl or aryl group; R includes an optionally substituted hydrocarbyl moiety having at least 5 carbon atoms; and wherein RCOO.sup. is the residue of a monoester of a diacid.

8. A method according to claim 1 wherein the quaternary ammonium compound has the formula (Y): ##STR00034## wherein R.sup.1, R.sup.2 and R.sup.3 are each independently selected from an optionally substituted alkyl, alkenyl or aryl group; R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are each independently selected from hydrogen or an optionally substituted alkyl, alkenyl or aryl group; and R includes an optionally substituted alkyl or alkenyl moiety having at least 6 carbon atoms; and wherein RCOO.sup. is the residue of a monoester of a diacid.

9. A method according to claim 1 wherein each of R.sup.1, R.sup.2 and R.sup.3 is selected from an alkyl or hydroxyl alkyl group having 1 to 10 carbon atoms.

10. A method according to claim 1 wherein epoxide (b) is selected from styrene oxide, ethylene oxide, propylene oxide, butylene oxide, epoxyhexane, octene oxide, stilbene oxide, other alkyl and alkenyl oxides having 2 to 50 carbon atoms, glycidyl ethers and glycidyl esters.

11. A method according to claim 1 wherein the fuel is diesel fuel and optionally comprises one or more further detergents selected from: (i) an additional quaternary ammonium salt additive which is not a quaternary 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 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.

12. A method according to claim 1 wherein the fuel is gasoline fuel and optionally comprises one or more gasoline detergents selected from: (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.

13. A method of improving the performance of an engine, the method comprising: preparing a fuel composition according to the method of claim 1; and combusting said fuel composition in the engine.

14. A method according to claim 13 wherein the engine is a gasoline engine and the fuel is gasoline.

15. A method according to claim 13 wherein the engine is a diesel engine having a fuel injection system which comprises a high pressure fuel injection (HPFI) system with fuel pressure greater than 1350 bar.

16. A method according to claim 13 wherein improvement in performance is achieved by combating deposits in the engine.

17. A method according to claim 13 which combats internal diesel injector deposits.

18. A method according to claim 13 which combats external diesel injector deposits, including injector nozzle deposits and injector tip deposits.

19. A method according to claim 13 which combats fuel filter deposits.

20. A method according to claim 13 which achieves keep clean performance.

21. A method according to claim 13 which achieves clean up performance.

Description

EXAMPLE 1

[0475] Additive A1 was prepared as follows.

[0476] A sample of polyisobutenyl succinic anhydride prepared from 1000MW pib (PIB1000SA) was hydrolysed by reaction with a slight excess of water at 90-95 C. The acid value of the resulting PIB1000SAcid was determined to be 1.50 mmol/g by titration against 0.1 N lithium methoxide in toluene.

[0477] The PIB1000SAcid sample (50.10 g, 75 mmol CO2H) was charged to a 3-neck round bottom flask. The flask was fitted with N2 flush, reflux condenser, stirrer-bar and thermocouple well. An oil bath thermostatically controlled to maintain 105 C. was used to heat the flask contents with stirring. The flask was charged with Shellsol AB (70.73 g) and was heated with strong stirring to 95 C. Water (3.384 g, 188 mmol, 2.51 equivalents to CO2H) was added forming a turbid solution.

[0478] N,N-Dimethyl ethanolamine (6.76 g, 76 mmol, 1.0 equivalents) was then added. This significantly reduced but did not remove the turbidity. FTIR confirmed the formation of an amine salt. After a further two hours a second FTIR spectrum was essentially unchanged from the first.

[0479] 2-ethylhexylglycidyl ether (14.06 g, 75.6 mmol, 1.01 equivalents) was added, dropping the temperature from 94 to 88 C. Heating continued and after a further 90 minutes at a temperature of 95 C. a further FTIR spectrum was acquired. The peak associated with the carboxylate salt had shifted slightly to 1574 cm-1 and approximately doubled in height relative to the CH.sub.2 absorbances at 1463 and 1455 cm-1. Additive A1, the di-quaternary ammonium salt of PIB1000SAcid via the ring-opening of 2-ethylhexylglycidyl ether with N,N-dimethyl ethanolamine was formed as a 50% solution in aromatic solvent.

##STR00029##

EXAMPLE 2

[0480] Further compounds of the invention and comparative compounds were prepared using a method analogous to example 1 except that the acid was replaced by an acid having the formula HOOCCHRCH.sub.2COOH, as follows:

TABLE-US-00001 Compound R A2 750 MW PIB A3 440 MW PIB A4 260 MW PIB A5 n-C18 A6 n-C12 A7 (comparative) H

[0481] In each case the same amine and epoxide as example 1 were used.

EXAMPLE 3

[0482] Additive A8 was prepared as follows.

[0483] A 100 cm.sup.3 3-neck round-bottom flask was charged with PIB1000SA (19.73 g, 15.4 mmol of anhydride by LiOMe titration) and 2-ethylhexanol (2.008 g, 15.4 mmol, 1.008 equivalents).

[0484] The flask was fitted with N2 flush, reflux condenser, stirrer-bar and thermocouple well. An oil bath thermostatically controlled to maintain 105 C. was used to heat the flask contents with stirring to 83 C. The temperature of the oil bath thermostat was re-set to 110 C. Reaction monitoring by FTIR confirmed that the reaction was substantially complete and a half-ester, half-acid formed after one hour. A further aliquot of 2-ethylhexanol (0.204 g, 0.1 equivalents) was added and FTIR used to confirm that no further reaction had occurred after a further 40 minutes.

[0485] A previously prepared sample of PIB1000SI-DMAPA (reaction product of PIB1000SA with N,N-dimethyl propylamine, 21.18 g, 15.5 mmol, 1.01 equivalents) and 2-methylphenylglycidyl ether, 2.526 g, 15.4 mmol, 1.0 equivalents) were added to the reaction flask. FTIR monitoring showed that a peak at about 1589 cm-1, consistent with formation of a carboxylate salt, began to form immediately. After 3 hours the peak had doubled in intensity and shifted to 1573 cm-1. No further changes were noted on further heating.

[0486] The material was allowed to cool then warmed back to 60 C. before adding Caromax 20 solvent (45.52 g for a total 50.2% inactives) to the highly viscous material. A homogeneous mixture was formed comprising Additive A2 as a 50% solution in aromatic solvent.

##STR00030##

EXAMPLE 4

[0487] Additive A9 of the invention was prepared using a method analogous to that described in example 1. In this case 2 molar equivalents of dimethylethanolamine were reacted with 2 molar equivalents of dodecylene oxide and one equivalent of dodecenyl succinic acid.

EXAMPLE 5 (COMPARATIVE)

[0488] Additive A10 (not of the invention) was prepared from dimethylethanolamine, 2-ethylhexyl glycidyl ether and acetic acid.

EXAMPLE 6 (COMPARATIVE)

[0489] Additive B is a 60% active ingredient solution (in aromatic solvent) of a polyisobutenyl succinimide obtained from the condensation reaction of a polyisobutenyl succinic anhydride derived from polyisobutene of Mn approximately 750 with a polyethylene polyamine mixture of average composition approximating to tetraethylene pentamine. The product was obtained by mixing the PIBSA and polyethylene polyamine at 50 C. under nitrogen and heating at 160 C. for 5 hours with removal of water.

EXAMPLE 7 (COMPARATIVE)

[0490] Additive C

[0491] A reactor was charged with 33.2 kg (26.5 mol) PIBSA (made from 1000MW PIB and maleic anhydride) and heated to 90 C. DMAPA (2.71 kg, 26.5 mol) was charged and the mixture stirred for 1 hour at 90-100 C. The temperature was increased to 140 C. for 3 hours and water removed. Methyl salicylate (4.04 kg, 26.5 mol) was charged and the mixture held at 140 C. for 8 hours. Caromax 20 (26.6 kg) was added.

EXAMPLE 8

[0492] Diesel fuel compositions were prepared comprising the additives listed in Table 1, added to aliquots all drawn from a common batch of RF06 base fuel, and containing 1 ppm zinc (as zinc neodecanoate).

TABLE-US-00002 TABLE 1 Fuel Composition Additive (ppm active) 1 A1 50 2 B 60 3 C 60

[0493] Table 2 below shows the specification for RF06 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 C. 5 EN 116 Plugging 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 KOH/g 0.02 ASTM D 974 (Strong Acid) Number Oxidation Stability mg/mL 0.025 EN ISO 12205 HFRR (WSD1,4) m 400 CEC F-06-A-96 Fatty Acid Methyl prohibited Ester

EXAMPLE 9

[0494] Fuel compositions 1 to 3 listed in table 1 were tested according to the CECF-98-08 DW 10 method.

[0495] The engine of the injector fouling test is the PSA DW10BTED4. In summary, the engine characteristics are:

[0496] Design: Four cylinders in line, overhead camshaft, turbocharged with EGR

[0497] Capacity: 1998 cm.sup.3

[0498] Combustion chamber: Four valves, bowl in piston, wall guided direct injection

[0499] Power: 100 kW at 4000 rpm

[0500] Torque: 320 Nm at 2000 rpm

[0501] Injection system: Common rail with piezo electronically controlled 6-hole injectors.

[0502] Max. pressure: 1600 bar (1.610.sup.8 Pa). Proprietary design by SIEMENS VDO

[0503] Emissions control: Conforms with Euro IV limit values when combined with exhaust gas post-treatment system (DPF)

[0504] 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.

[0505] The test is run with a future injector design representative of anticipated Euro V injector technology.

[0506] 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.

[0507] Full details of the CEC F-98-08 test method can be obtained from the CEC. The coking cycle is summarised below.

[0508] 1. A warm up cycle (12 minutes) according to the following regime:

TABLE-US-00004 Duration Engine Speed Torque Step (minutes) (rpm) (Nm) 1 2 idle <5 2 3 2000 50 3 4 3500 75 4 3 4000 100

[0509] 2. 8 hrs of engine operation consisting of 8 repeats of the following cycle

TABLE-US-00005 Duration Engine Speed Load Torque Boost Air After Step (minutes) (rpm) (%) (Nm) IC ( 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

[0510] 3. Cool down to idle in 60 seconds and idle for 10 seconds

[0511] 4. 4 hrs soak period

[0512] 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, i.e. 56 hours total test time excluding warm ups and cool downs.

[0513] The results of these tests are shown in FIG. 1.

EXAMPLE 10

[0514] The effectiveness of the additives detailed in table 3 below in older engine types was assessed using a standard industry testCEC test method No. CEC F-23-A-01.

[0515] 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.

[0516] 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.

[0517] 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-00006 Stage Time (secs) Speed (rpm) Torque (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

[0518] 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.

[0519] The results of this test using the specified additive combinations of the invention are shown in table 3. In each case the specified amount of additive was added to an RF06 base fuel meeting the specification given in table 2 (example 8) above.

TABLE-US-00007 TABLE 3 XUD-9 Composition Additive (ppm active) % Average Flow Loss None 69.0 4 A1 (50) 1.8 5 A2 (50) 2.0 7 A3 (50) 4.0 8 A4 (50) 13.0 9 A5 (50) 2.8 10 A6 (50) 1.3 11 (comparative) A7 (50) 45.6 12 A8 (50) 6.3 13 A9 (50) 5.6 14 (comparative) A10 (50) 40.8 15 (comparative) B (60) 25.5

[0520] These results show that the quaternary ammonium salt additives of the present invention achieve an excellent reduction in the occurrence of deposits in traditional diesel engines.

EXAMPLE 11

[0521] Additive A11, a further additive of the invention was prepared as follows:

[0522] With FTIR monitoring, a sample of technical grade oleic acid (Fisher, 15.31 g) was caused to mix with iso-propylglycidyl ether (6.36 g) by magnetic stirring before addition of water (3.90 g) and finally N, N-dimethyl ethanolamine (14.45 g). Amine addition was accompanied by a temperature rise from 21 to 30 C., controlled by raising up an oil bath at ambient temperature around the flask. After the initial exotherm had died down, the oil bath heater was turned on and set to provide 100 C. After three hours at an internal temperature of 94-95 C. the reaction was adjudged, by FTIR, to be complete. The reaction mass was transferred to a pear-shaped flask and stripped at the rotary evaporator at 100 C., 9 mBar. Mass balances were consistent with formation of the desired 2-hydroxy-N-(2-hydroxyethyl)-3-isopropoxy-N,N-dimethylpropan-1-aminium salt of oleic acid. A trace of ester was apparent in the IR spectra.