USE AND METHOD

Abstract

The use of nitrogen-containing compounds as additives in a diesel fuel composition reduce the impact of deposits in the exhaust gas recirculation system of a diesel engine when combusting said diesel fuel composition. The nitrogen-containing compounds include at least 4% by mass of nitrogen atoms and in some embodiments fewer than five NH bonds.

Claims

1. Use of one or more nitrogen-containing compounds as an additive in a diesel fuel composition to reduce the impact of deposits in the exhaust gas recirculation system of a diesel engine when combusting said diesel fuel composition, wherein the nitrogen-containing compounds comprise at least 4% by mass of nitrogen atoms.

2. A method of reducing the impact of deposits in the exhaust gas recirculation system of a diesel engine, the method comprising combusting in the engine a diesel fuel composition comprising as an additive one or more nitrogen-containing compounds, wherein the nitrogen-containing compounds comprise at least 4% by mass of nitrogen atoms.

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

4. 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.

5. The method of claim 2, wherein the nitrogen-containing compound is the reaction product of a) a hydrocarbyl substituted reagent and b) a nitrogen-containing reagent.

6. The method of claim 2, wherein the nitrogen-containing compound has the formula (I):
A-L-R.sup.1 (I) wherein: A is a nitrogen-containing group; L is either a bond or a linker group; and R.sup.1 is an optionally substituted alkyl, alkenyl or aminoalkyl group having a molecular weight (Mn) of up to 1,000.

7. The method of claim 6, wherein the nitrogen-containing group A is a nitrogen-containing heterocycle and is selected from an optionally substituted piperazine, pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, quinazoline, a five-membered heterocyclic ring such as pyrazole or imidazole or a benzo-fused five-membered heterocyclic ring such as benzimidazole.

8. The method of claim 6, wherein the A group is a non-cyclic nitrogen-containing group having the formula (II): ##STR00037## wherein n is from 1 to 10.

9. The method of claim 6, wherein L is a bond, an amide, a succinimide, a succinic acid or an amide of a succinic acid.

10. The method of claim 2, wherein the nitrogen-containing compound is the reaction product of: a) a hydrocarbyl substituted carboxylic acid acylating agent; and b) a nitrogen-containing reagent.

11. The method of claim 10, wherein component a) has the formula (aI): ##STR00038## wherein R.sup.1 is an optionally substituted alkyl, alkenyl or aminoalkyl group having a molecular weight (Mn) of up to 1,000.

12. The method of claim 10, wherein component b) is either: selected from an optionally substituted benzotriazole, amino-benzotriazole, indazole, amino-indazole, triazole, amino-triazole, tetrazole or amino-tetrazole; or has the formula (bI): ##STR00039## wherein n is from 1 to 10.

13. The method of claim 2, wherein the nitrogen-containing compound has the formula (III): ##STR00040## wherein: A is a nitrogen-containing group; R.sup.1 is an optionally substituted alkyl, alkenyl or aminoalkyl group having a molecular weight of up to 1,000; and R.sup.2 is OH, NH.sub.2, OR.sup.4, NHR.sup.4 or NR.sup.4R.sup.5, wherein R.sup.4 and R.sup.5 are independently selected from optionally substituted C1-6 alkyl or alkenyl groups, or is a bond to A.

14. The method of claim 13, wherein the nitrogen-containing compound has the formula (IV), (IVb) or (IVc), or a mixture thereof: ##STR00041## wherein R.sup.1 and R.sup.2 are as defined in claim 12.

15. The method of claim 13, wherein the nitrogen-containing compound has the formula (V): ##STR00042## wherein n is from 1 to 3, or a mixture thereof; and wherein R.sup.1 is as defined in claim 12.

16. The method of claim 2, wherein the nitrogen-containing compound is the reaction product of: a) an amine or polyamine comprising a hydrocarbyl group; b) a nitrogen-containing reagent; and c) an aldehyde.

17. The method of claim 16, wherein: a) is an alkylamine having the formula NHR.sup.7R.sup.8 wherein R.sup.7 and R.sup.8 are each independently selected from H, optionally substituted C1-20 alkyl groups or optionally substituted C1-20 alkenyl groups; b) is a nitrogen-containing reagent selected from an optionally substituted triazole, tetrazole, indole, indazole or benzotriazole, and c) is formaldehyde or a source of formaldehyde.

18. The method of claim 2, wherein the nitrogen-containing compound has the formula (VI): ##STR00043## wherein: R.sup.1 is an optionally substituted alkyl, alkenyl or aminoalkyl group having a molecular weight of up to 1,000; W, X, Y and Z are each independently selected from CH, C, N, NH, S and SH; and wherein the compound optionally comprises a cycloalkyl or aryl ring linking Y and Z.

19. The method of claim 18, wherein the nitrogen-containing compound has the formula (IX): ##STR00044## wherein: R.sup.1 is an optionally substituted alkyl, alkenyl or aminoalkyl group having a molecular weight of up to 1,000; W and X are each independently selected from C and N; and each R.sup.6 is independently selected from H, C1-6 alkyl or C1-6 alkenyl.

20. The method of claim 19, wherein R.sup.1 is CH.sub.2NR.sup.7R.sup.8 and R.sup.7 and R.sup.8 are each independently selected from H, optionally substituted C1-20 alkyl groups or optionally substituted C1-20 alkenyl groups.

21. The method of claim 2, wherein the nitrogen-containing compound comprises fewer than five NH bonds.

22. The method of claim 2, wherein the diesel fuel composition comprises from 50 to 2000 ppm of the one or more nitrogen-containing compounds.

23. The method of claim 2, wherein the diesel fuel composition comprises from 50 to 350 ppm of the one or more nitrogen-containing compounds.

24. The method of claim 2, which reduces deposits in the exhaust gas recirculation system of a diesel engine having a pressure in excess of 1350 bar.

25. The method of claim 2, which reduces the formation of deposits on the cooler of the EGR system.

26. The method of claim 2, which reduces the formation of deposits in an EGR system by at least 5%.

27. The method of claim 2, wherein the diesel fuel composition comprises one or more nitrogen containing detergents.

28. The method of claim 27 wherein the one or more nitrogen containing detergents are selected from: (i) a quaternary ammonium salt additive; (ii) the product of a Mannich reaction between an aldehyde, an amine and an optionally substituted phenol; and (iii) the reaction product of a carboxylic acid-derived acylating agent and an amine.

29. A fuel additive composition comprising one or more nitrogen-containing compound and a detergent additive, wherein the nitrogen-containing compounds comprise at least 4% by mass of nitrogen atoms.

30. A diesel fuel composition comprising one or more nitrogen-containing compound and a detergent additive, wherein the nitrogen-containing compounds comprise at least 4% by mass of nitrogen atoms.

31. The diesel fuel composition according to claim 30, comprising one or more further additives selected from antioxidants, dispersants, detergents, metal deactivating compounds, wax anti-settling agents, cold flow improvers, cetane improvers, dehazers, stabilisers, demulsifiers, antifoams, corrosion inhibitors, lubricity improvers, dyes, markers, combustion improvers, metal deactivators, odour masks, drag reducers and conductivity improvers.

32. The fuel additive composition according to claim 29 or the diesel fuel composition according to claim 30 or claim 31, wherein the detergent additive is: a reaction product of tetraethylene pentamine (TEPA) and a PIBSA having a PIB number average molecular weight (Mn) of from 300 to 2800; or a quaternary ammonium salt formed by reacting methyl salicylate or dimethyl oxalate with the reaction product of dimethylaminopropylamine and a polyisobutylene-substituted succinic anhydride having a PIB number average molecular weight (Mn) of 700 to 1300; or a mixture thereof.

Description

EXAMPLES

[0364] Example nitrogen-containing compounds for use as additives in a diesel fuel composition according to the invention were prepared as follows.

Example 1-PIB.SUB.260.SA 5-amino-[1H]-tetrazole Reaction Product

Major Components:

##STR00027##

[0365] The nitrogen-containing compound of Example 1 was prepared as follows. Thermal reaction of a high-reactive grade of 260 number average highly reactive (HR) poly(isobutene) (PIB.sub.260) with maleic anhydride (MA) provided a sample of poly (isobutene) succinic anhydride (PIB260SA). The PIB.sub.260SA was characterised in part by titration against lithium methoxide and found to have an activity of 2.38 mmol.Math.g.sup.1.

[0366] A reactor was charged with a sample (135.01 g, 321.3 mmol) of the PIB.sub.260SA and Caromax20 solvent (162.3 g) and heated to 90 C. 5-amino-[1H]-tetrazole monohydrate (33.10 g, 321.1 mmol) was added and the flask contents were heated to above 100 C. for an hour. Following this the temperature was increased to achieve an internal temperature of 170 C., facilitating the formation of the amide. progress of the reaction was monitored using ATR-FTIR.

[0367] Nitrogen contents for three essentially identically prepared samples were determined by analysis using a Leco Flash 1112 series analyser and found to range from 6.45 to 6.53 wt %. The theoretical nitrogen content of the target compound is from 15.1 to 17.2 wt %.

Example 2-C16/C18 ASA 5-amino-[1H]-tetrazole Reaction Product

Major Components:

##STR00028##

wherein the R.sup.3 groups sum to C.sub.13H.sub.28 or C.sub.15H.sub.32 or a mixture thereof.

[0368] The nitrogen-containing compound of Example 2 was prepared as follows. The activity of a sample of Pentasize 68 (a commercially available C16 to C18 alkenyl succinic anhydride (ASA)) was determined by lithium methoxide titration to be 2.97 mmol.Math.g.sup.1. A reaction flask was charged with 16.86 g (50 mmol activity) in a high aromatic solvent Innosol PP (20.256 g). 5-amino-[1H]-tetrazole monohydrate (5.164 g 50 mmol) was added and stirred to form a dispersion.

[0369] The dispersion was heated using a thermostat-controlled oil bath to an eventual internal temperature of 170 C. Progress of the reaction was monitored at intervals using ATR-FTIR spectroscopy. The product contained approximately 50 wt % of the C16/C18 ASA 5-amino-[1H]-tetrazole reaction product. The theoretical nitrogen content of the target compound is from 16.1 to 17.8 wt %.

Example 3-Imide from Reaction of C16/C18 ASA with Tetraethylenepentamine (TEPA)

Major components:

##STR00029##

wherein the R.sup.3 groups sum to C.sub.13H.sub.28 or C.sub.15H.sub.32 or a mixture thereof.

[0370] The nitrogen-containing compound of Example 3 was prepared as follows. The activity of a sample of Pentasize 68 (a commercially available C16 to C18 alkenyl succinic anhydride (ASA)) was determined by lithium methoxide titration to be 2.97 mmol.Math.g.sup.1. A reaction flask was charged with 150.02 g (446 mmol activity) of Pentasize 68 and 2-ethylhexan-1-ol solvent (234.09 g). A pressure-equalised dropping funnel was charged with TEPA (84.40 gg, 446 mmol, 1.0 moles per anhydride group). The flask contents were warmed in an oil bath controlled by a thermostat set at 70 C. The oil bath set point was increased to 175 C. and the reactor contents allowed to warm.

[0371] Reaction progress was monitored at intervals using ATR-FTIR spectroscopy. The product comprised 49.88 wt % of the imide products. The theoretical nitrogen content of the target compound is from 13.0 to 13.7 wt %.

Example 4Mannich Reaction Product of Diethylamine, Formaldehyde and Benzotriazole

Major Components:

##STR00030##

[0372] The nitrogen-containing compound of Example 4 was prepared as follows. Following the method of Katritzky et al J Chem Soc Perkin Trans 1987, 2673, diethylamine (21.945 g, 301 mmol) was added to methanol (100 cm.sup.3). This mixture was cooled back to 3 C. and 1H benzotriazole (35.739 g, 301 mmol) was added. Aqueous formaldehyde (nominally 37 wt %, 24.324 g, 300 mmol, 1.0 equivalents) was added to the reactor over 10 minutes and the reaction mixture was stirred for 50 minutes before being allowed to warm to ambient temperature whilst stirring overnight. Methanol was removed at the rotary evaporator and 58.441 g (expected 61.33 g) of a slightly viscous yellow oil were recovered.

[0373] The product obtained was confirmed by comparison of the ATR-FTIR spectra with the literature. .sup.1H NMR was consistent with the Katritzky reference but indicated a ratio of 1-isomer to 2-isomer of 3.71. The product was found by a Thermoflash elemental analyser to contain 62.24 wt % C, 7.55 wt % H and 27.09 wt % N. The theoretical nitrogen content of the target compound is 27.4 wt %.

[0374] A solution at 63.5 wt % of the target compound in 2-ethylhexanol gave clean and bright diesel fuel solutions at up to 5 wt % active material.

Example 5Two Phase Mannich Reaction Product of Diethylamine, Formaldehyde and Benzotriazole

Major Components:

##STR00031##

[0375] A reaction flask was charged with benzotriazole powder (60.0 g, 0.504 mol) and solvent 150 (102.8 g). The slurry was warmed to 30 C. before diethylamine (15.1 g) was added. Aqueous formaldehyde (36.8 g of a 37 wt % formaldehyde solution) was then added over a period of 25 minutes, keeping the temperature at 40-47 C. After two hours stirring at 40 C. the reactor contained two liquid phases which were heated to 70 C. before transfer to a separating funnel. The recovered aqueous phase comprised 27.4 g of material. Additional water, accompanied by some organics, was removed by vacuum distillation at 70 C., 25 mBar leaving a clear solution of organic material.

[0376] The product structure was confirmed by FTIR. Theoretical N content of this product is 13.7 wt %.

Example 6Two Phase Mannich Reaction Product of Benzotriazole, Formaldehyde and bis(2-ethylhexyl)amine

Major Components:

##STR00032##

[0377] The nitrogen-containing compound of Example 6 was prepared as follows. A reaction flask was charged with benzotriazole powder (50.1 g, 0.421 mole) and 157 g of solvent 150. The slurry was warmed to approximately 30 C. before adding bis(2-ethylhexyl) amine (101.7 g) over 20 minutes, followed by 34.1 g of 37 wt % active formaldehyde solution.

[0378] The reaction mixture was heated to 80 C. and transferred to a separating funnel and the organic layer was separated. Distillation of water from the separated organic layer resulted in a clear organic phase giving an FTIR spectrum similar to that of the product of Example 5.

[0379] The theoretical nitrogen content of the target compound is 15.0 wt %.

Example 7Two Phase Mannich Reaction Product of 1,2,4-triazole, Formaldehyde and di-n-butylamine

Major Component:

##STR00033##

[0380] The nitrogen-containing compound of Example 7 was prepared as follows. 1,2,4-triazole (40.4 g, 0.585 mole) and 133.6 g of solvent 150 were charged to a reaction flask, followed by the di-n-butylamine (75.6 g). After further warming (39 C.), addition of the aqueous formaldehyde (47.4 g of 37 wt % solution) commenced.

[0381] The organic layer was separated from the reaction mixture and dried by vacuum distillation to yield the 249.6 g of the product solution. Theoretical N content of the product mixture (including solvent) is 13.3 wt %, by analysis the concentrate contained 13.0 wt % N, 60.8 wt % C and 8.7 wt % H.

[0382] The theoretical nitrogen content of the target compound is 26.6 wt %.

Example 8: benzotriazole-formaldehyde-dibutylamine

Major Components:

##STR00034##

[0383] In a 500 ml round bottomed flask, charged benzotriazole (60.1 g, 0.505 moles, 1.0 eq) and A150 solvent (131.5 g) and heated to 30 C., forming a white slurry. Added dibutylamine (65.3 g, 1 eq, 0.505 moles) via dropping funnel over 25 mins. With the mixture in the flask at 31 C., formalin addition (37% w/w, 41.0 g, 0.505 moles, 1.0 eq) started and carried out of a period of 15-20 mins. A milky white liquid forms immediately after addition, with the contents two phases. The temperature of the reactor contents were then adjusted to 45-50 C. and held at this temperature for 5 hrs. The reaction mixture was allowed to cool overnight. To separate the reaction mixture, it was heated to 70 C. The separation is clear, and the lower now hazy aqueous layer was ran off. Collected 30.9 g, theoretical water in the reaction is 34.9 g. Heated the organic phase to 75 C. and applied vacuum to 20 mbar. Isolated 254.9 g of clear bright yellow liquid (as 50% actives solution).

[0384] The theoretical nitrogen content of the target compound is 21.5 wt %.

Example 9: Benzotriazole-formaldehyde-Armeen 2C (dicocoalkylamine)

Major Components:

##STR00035##

[0385] In a 500 ml round bottomed flask, charged benzotriazole (26.0 g, 0.218 moles, 1.0 eq) and A150 solvent (116.0 g) and heated to 90 C. The flask was charged the Armeen 2C (87.4 g, 0.218 moles, 1 eq [equivalent weight is 401 g/mol]) (dicocoalkylamine wherein cocoalkyl=mixture of C6-18 alkyl). Formalin (37% w/w, 0.218 moles, 1.0 eq) was then added over 5 mins and then the reaction mixture was stirred at 90 C. for 2.5 hrs. The temperature in the reaction flask was increased over a period of 3 hrs to 119 C. and water removed via Dean and Stark trap. When no further aqueous phase was being collected and the product was clear and bright the temperature was cooled to ambient. Collected 222.5 g of clear bright amber liquid (as 50% actives solution).

Example 10: 1,2,4-triazole-formaldehyde-bis (2-ethylhexyl)amine

Major Component:

##STR00036##

[0386] Formalin (159.6 g of 26.6% active formaldehyde, 1.9447 mol, 0.995 eqs) and 1,2,4-triazole (156.0 g, 1.9545 mols, 1.0 equiv) are charged and heated to 60 C. Bis-(2-ethylhexyl) amine (462.5 g, 1.9154 mols, 0.98 equivs) is added to the water mixture over 2.5 hrs at 60 C. and the batch is stirred for 1 hr to complete reaction. Water from the formalin solution and water of reaction is removed by vacuum distillation and 60-100 C. (100-200 mbar). Following water removal, residual volatiles and trace water are removed by stripping under increased vacuum and the product (615.4 g) is discharged via a filter as pale-yellow liquid.

[0387] The theoretical nitrogen content of the target compound is 17.4 wt %.

Engine Testing

[0388] Engine testing was carried out as described below to assess the performance of the nitrogen-containing additives of the present invention in the reduction of deposits in the exhaust gas recirculation system of a diesel engine.

Engine Details

[0389] 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 1100h of use prior to the first test. The engine oil was changed prior to performing the first test.

Modifications/Test Setup

[0390] 1. No SCR Catalyst or associated components were present in the exhaust system. [0391] 2. High pressure EGR cooler is artificially controlled to 40 C. for the duration of the test.

[0392] The base fuel was an RF-06-03 diesel fuel (Haltermann Carless, UK) having the following specification:

TABLE-US-00001 Feature Units Results Minimum Method Density 15 C. kg/m 836.0 833.0 837.0 ASTM D4052 Marker (Red) Pass VISUAL Ceta e Number 53.9 52.0 54.0 ASTM D 13 .B.P C. 214.3 ASTM D 10% v/v Recovered at C. 232.0 ASTM D 50% v/v Recovered at C. 275.5 245.0 ASTM D 90% v/v Recovered at C. 330.2 ASTM D 95% v/v Recovered at C. 348.0 345.0 350.0 ASTM D F.B.P C. 356.2 370.0 ASTM D Aromatics by FIA % (V/V) 19.8 Corrected for ASTM D131 Olefins by FIA % (V/V) 5.5 Flash Point, Pensky Closed C. 92.0 55.0 ASTM D Sulphur Content mg/kg <3.0 10.0 ASTM D5453 Viscosity at. 40 C. mm2/s 3.0 2 2.300 3.300 ASTM D445 Cloud Point C. 18 ASTM D2500 CFPP C. 20 15 EN 11 Lubricity (WSD 1.4) at 60 C. m 180 400 ISO 1215 -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 100 ml 2.5 ASTM D2274 Copper Corrosion, 3 hrs at 100 C. 1B ASTM D130 Oxygen Content % (m/m) <0.04 ELEMENTAL Elemental Analysis Carbon Content % (m/m) 8 .89 ASTM D5291 ASTM D5291 Hydrogen Content % (m/m) 13.11 ASTM D5291 ASTM D5291 Carbon Weight Fraction 0.8 8 CALCULATION Calculation C/H Mass Ratio 6.63 CALCULATION Calculation Atomic H/C Ratio 1.797 CALCULATION Calculation Atomic O/C Ratio <0.0003 CALCULATION Calculation Gross Heat of Combustion M /kg 45.72 IP 12 IP 12 Net Heat of Combustion M /kg 42.94 IP 12 IP 12 Net Heat of Combustion btu/lb 18460 CALCULATION Calculation indicates data missing or illegible when filed

Test Additives, Treat Rate:

[0393] The example nitrogen-containing compounds were dosed at 100 mg/kg into the base diesel fuel described above. The nitrogen-containing compound of Example 1 was dosed into the base fuel to provide test fuel A

[0394] The quantity of soot deposited in the EGR cooler was established by weighing the component before and after each test.

[0395] 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.

[0396] 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.

Test Procedure

[0397] [D] EGR Cleaned and weighed [0398] [D] DPF+Slave EGR Installation [0399] Engine Start+Warm-Up [0400] 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. [0401] Engine Stop [0402] Change to test fuel [0403] [C] DPF+Slave EGR Removal [0404] [C] DPF Start-of-Test (SOT) Weighing [0405] [C] DPF+[C] EGR Installation [0406] Engine Start+Warm-Up [0407] 8-Hour Steady-State Test Cycle [0408] 1200 RPM [0409] 60 Nm [0410] Engine Stop [0411] [D] DPF Removal and End-of-Test (EOT) Weighing [0412] [D] EGR Removal and EGR End of Test Weighing [0413] [C] indicates a clean component [0414] [D] indicates a fouled component

Results

TABLE-US-00002 Treat rate EGR Soot Test fuel Additive (mg/kg) Weight [g] Base fuel 1.59 A Example 1 100 1.25

[0415] These results demonstrate that the use of the nitrogen-containing compounds described herein as additives 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.