DESC:ADDITIVE COMPOSITION TO IMPROVE COMBUSTION AND REDUCE ENGINE DEPOSITS FOR PETROLEUM FUEL

FIELD OF INVENTION
The present invention discloses a fuel additive composition. More particularly, the invention relates to a fuel additive composition for controlling engine deposit and enhancing combustibility of fuel without effecting the fuel properties and process for preparing the same.

BACKGROUND OF THE INVENTION
All diesel and crude oil fuels form carbonaceous deposits in the fuel system of compression ignition engines. Particularly, the fuel injector nozzles of both direct and indirect engines are most prone to deposit formation. These deposits formation results in coating or adhere to injector parts and cause injector sticking, injector tip fuel metering passage fouling, nozzle hole plugging and delayed injection and hence delayed start of combustion. These processes generally occur during the first few hours of operation, and then persist throughout lifetime of the nozzles. These types of problems result in significantly increased fuel consumption, smoke emissions, increased engine noise, misfiring, low temperature or cold start problems, idle roughness, and decreased power output and fuel economy etc.

It has been observed that these engine problems are the result of long ignition delays and caused by deposits formation. This deposit formation causes an excessively rapid pressure rise in the cylinder once combustion does occur. Recent published literature suggests that the long ignition delay provides the time for certain chemical reactions to occur in the atomized fuel charge prior to ignition, resulting in products which burn exceedingly rapidly once combustion begins and thereby causing the undesirable rapid pressure rise and the resultant problems.

Polyisobutylene succinimide is a known compound with property of detergency in the prior art. Polyisobutylene succinimide functions as detergent and control the engine deposits during the burning of diesel fuel/heavy hydrocarbon stocks. To certain extent polyisobutylene succinimide also works as a dispersant and corrosion inhibitor.

Cetane improvers have been used for many years to improve the ignition quality of diesel fuels. The use of cetane improvers is increasing due to the increased demand for diesel fuel which has resulted in because of widening the fraction recovered the so called middle distillate fraction. For raising the low cetane number of diesel fuel, different types of additives have been synthesized and evaluated for cetane number determination of diesel fuel. These additives mainly include peroxides, nitrates, nitrites, azo compounds etc. Alkyl nitrates such as amyl nitrate, hexyl nitrate and mixed octyl nitrates have been used commercially with good results.

RELATED ART
U.S. Patent No. 5160649 discloses the synthesis and use of polyisobutenylene succinimide for lubricants or fuels. This compound is ashless detergent and is made from a Mannich condensation reaction between a hydrocarbyl bissuccinimide, such as a dimer of a polyisobutenyl succinimide (derived from tetraethylenepentamine), an aldehyde, such as formaldehyde, and a heteroatom substituted benzoic acid such as salicyclic acid, thiosalicyclic acid or aminosalicylic acid.

US Patent No. 5205945 describes the preparation and use of multifunctional antioxidant, antiwear and dispersancy additive for fuels and lubricants. The compound is a reaction product of a thiol-substituted diazole, such as aminomercaptothiadiazole (AMTD) or dimercaptothiadiazole (DMTD), an aldehyde and a hydrocarbon-substituted succinimide dimer. The succinimide dimer is derived from polyisobutenyl succinimide and tetraethylenepentamine which are reacted in a mole ratio of 2:1.

U.S. Patent No. 6210452 discloses fuel additives to control the formation of deposits in internal combustion engines, which comprise carboxylic acid alkoxylates suited for use with nitrogen containing fuel detergents.

International Publication WO 98/12282Al discloses a detergent additive composition for diesel fuel that contains a polyisobutylene monosuccinimide in an aromatic hydrocarbon diluents and this detergent additive composition can be used to remove or prevent engine deposits.
In U.S. Patent No. 6676715, Polyisobutylene succinimide reported as stabilizing agent for diesel fuel at higher temperature.

U.S. Patent No. 5332407 describes detergent additive to a diesel fuel and the main component used are 4-alkyl-2-morpholinone and alkylphenoxypolyoxyalkylene amine which work as detergent and actively cleans deposits from dirty diesel fuel injectors and keep engine clean.

WIPO Patent Application WO/2009/055518 discusses the preparation of succinimide dispersant produced by reacting a hydrocarbyl-substituted succinic anhydride and an amine having at least one primary amino group and at least one secondary amino group where the succinimide detergents are useful as additives in fuels.

U.S. Patent No. 5,482,518 describes the process/mechanism of “fuel ignition delay” in diesel engines. Diesel fuels of higher cetane number exhibit a shorter ignition delay than do diesel fuels of a lower cetane number. Therefore, higher cetane number diesel fuels are desirable to avoid diesel knock. Most diesel fuels possess cetane numbers in the range of about 40 to 55. A correlation between ignition delay and cetane number has been reported in “How Do Diesel Fuel Ignition Improvers Work” Clothier, et al., Chem. Soc. Rev, 1993, pg. 101-108. In this document, various additives for raising the cetane number of diesel fuel are discussed and these additives mainly include peroxides, nitrates, nitrites, azo compounds etc. Alkyl nitrates such as amyl nitrate, hexyl nitrate and mixed octyl nitrates have been used commercially with good results. Other nitrates such as 2-methyl-2-nitropropyl nitrate have also been suggested as cetane improvers but found shock sensitive. Generally, it is accepted that organic nitrates, more specifically 2-ethylhexyl nitrate, are the most cost-effective additives to improve cetane number of diesel.

As far as the synthesis of organic nitrate is concerned, it is well documented in the U.S. Patent No. 5,162,568 which discusses an improved process for preparing nitrates, such as ethylhexyl nitrate from alcohols such as ethylhexyl alcohol, using mixed nitric acid and sulfuric acid stabilized with urea, hydrazine or sulfamic acid.

Subsequently U.S. Patent No.4479905 discusses the synthesis of alkoxyalkyl nitrate wherein a mixture of aliphatic primary monohydric alcohol and alkoxyalkanol is continuously nitrated to yield an organic nitrate mixture containing substantial amounts of alkoxyalkyl nitrate useful as a cetane improver in diesel fuel.

U.S. Patent No. 20050160662 & Oryxe Energy International Jul, 28 2005: discusses the method and composition for using beta-carotene stabilized with 2, 2, 4-trimethyl-6-ethoxy-1, 2-dihydro-quinoline, as cetane improver in hydrocarbonaceous diesel fuels. The additive may be added to any liquid hydrocarbon fuel, solid hydrocarbon fuel, or other hydrocarbonaceous combustible fuel to reduce emissions of undesired components.

Despite the above prior arts, there is still felt a need to develop improved fuel additive systems to prevent formation of the deposit or to remove such deposits once they have formed and simultaneously to improve the ignition delay of diesel fuel for better fuel economy benefits.

STATEMENT OF THE INVENTION
Accordingly, the present invention provides an additive composition to improve combustion and reduce engine deposits, wherein the composition comprises a detergent and a cetane improver in the ratio of 1:0.3 to 1:2.
The present invention further provides a process for preparation of additive composition to improve combustion and reduce engine deposits, comprising blending a detergent and a cetane improver in a ratio of 1:0.3 to 1:2 at a temperature ranging between 20 to 40 ° C for a period of 1-2 hours.
The present invention furthermore provides a process of simultaneously improving combustion and reducing engine deposit, comprising adding the additive as mentioned above to a fuel in the range of 0.01 to 0.10 % v/v.
In an embodiment, the detergent is polyisobutylene succinimide.
In an embodiment, the detergent is having an average molecular weight of 700 to 1200.
In an embodiment, the cetane improver is 2-Ethyl Hexyl Nitrate.
In an embodiment, the additive optionally comprises a dehazer, corrosion inhibitor, lubricity improver and antistatic agent.
The present invention further provides a fuel composition comprising a base fuel having boiling point in the range of 150o to 370oC or crude oil having boiling point in the range of 0o to 900oC, a detergent and a cetane improver in a ratio of 1:0.3 to 1:2, wherein an amount of the detergent and cetane improver is in the base fuel is in the range of 0.01 to 0.10 % v/v.
In another embodiment the present invention provides a process for preparing a fuel, comprising mixing base fuel having boiling point in the range of 150o to 370oC or crude oil having boiling point in the range of 0o to 900oC with a detergent and a cetane improver, wherein the ratio of detergent and a cetane improver is in the range of 1:0.3 to 1:2 and amount of the detergent and cetane improver in the base fuel is in the range of 0.01 to 0.10 % v/v and wherein the mixing is performed at a temperature ranging between 20o C to 40o C for a time period in the range of 1 to 2 hours.
Furthermore, the present invention discloses a process of combustion comprising:
a. providing a fuel composition to a combustion chamber; and
b. providing conditions suitable for combustion of the fuel composition in the combustion chamber;
wherein the fuel composition comprises a base fuel having boiling point in the range of 150o to 370oC or crude oil having boiling point in the range of 0o to 900oC and an additive composition comprising a detergent and a cetane improver in a ratio of 1:0.3 to 1:2, and wherein an amount of the additive in the base fuel or crude oil is in the range of 0.01 to 0.10 % v/v.

SUMMARY OF THE INVENTION
The present invention relates to a fuel additive composition comprising a synergistic combination of detergent and cetane improver which is effective in improving the combustibility of fuel, removing deposits from dirty fuel injectors and keeping these injectors clean and thereby improving the fuel economy of the diesel fuel /crude oil. The additive system prevents formation of the deposit or removes such deposits once they have formed and simultaneously improves the ignition delay of diesel fuel for better fuel economy benefits without effecting the fuel properties and process for preparing the same. The present invention also relates to a process for preparing the fuel additive composition as mentioned above. The present invention further relates to a fuel composition containing the fuel additive composition as mentioned above and a process for preparing such fuel composition and a process of combustion of such fuel composition.

DESCRIPTION OF THE INVENTION
The present invention relates to an additive composition for fuels that improves combustion, reduces the engine deposits and provides fuel efficiency in main line engines run on fuels such as diesel /crude oil. According to the present invention the fuel additive composition comprises a synergistic combination of detergent and cetane improver in a ratio of 1:0.3 to 1:2, which is effective in improving the combustibility of fuel, removing deposits from dirty diesel fuel injectors and keeping these injectors clean and thereby improving the fuel economy of the diesel fuel /crude oil.

The composition/formulation provides protection against corrosion by forming coating over the metallic surface of engine parts without affecting the properties of the fuel.

According to the invention, there is provided an easy and economical process for the preparation of the fuel additive composition by blending the detergent and cetane (ignition) improver in a ratio in the range of 1:0.3 to 1:2 at ambient/room temperature for a period of up to 1- 2 hour.

According to the invention, there is provided a fuel composition comprising a base fuel having boiling point in the range of 150o to 370oC or crude oil having boiling point in the range of 0o to 900oC and an additive composition comprising a detergent and a cetane improver in a ratio of 1:0.3 to 1:2, wherein an amount of the additive in the base fuel is in the range of 0.01 to 0.10 % v/v.

Further the invention also relates to a process for the preparation of the fuel composition comprising of blending of an additive composition comprising a detergent and a cetane improver in a ratio of 1:0.3 to 1:2, wherein an amount of the additive in the base fuel is in the range of 0.01 to 0.10 % v/v with a diesel fuel/crude oil having boiling point in the range of 150o to 370o C/ boiling point in the range of 0o to 900oC at an ambient temperature or slightly at higher temperature in case of heavy crude oil for 1 to 2 hours.
According to the invention, the fuel additive (deposit control) composition of detergent polyisobutylene succinimide and cetane improver works in a synergetic manner for the deposit control and enhances the cetane number of fuel. Its further incorporation into the diesel fuel showed appreciable improvement in deposit control characteristics relating to injector cleanliness as well as enhancement of cetane number of fuel as compared to any of the aforesaid components are added alone/singularly to the diesel fuel.

According to the invention the fuel additive is provided in an additive package comprising a synergistic combination of (a) detergent and (b) cetane improver. In an embodiment of the invention the fuel additive is provided in an additive package comprising a synergistic combination of (a) polyisobutylene succinimide and (b) cetane improver.

Further, according to an embodiment of the present invention a deposit control (fuel additive composition) additive formulation is provided comprising (a) deposit control agent and (b) cetane improver and optionally dehazer, corrosion inhibitor, lubricity improver and antistatic agent.

According to the invention the cost effective and fuel efficient additive composition and method described herein is effective for controlling and reducing the deposits on engine surfaces along with improvement in the cetane number and improvement in Specific Fuel Consumption (SFC) of diesel and crude oil engines as well.

According to the present invention, there is provided a fuel composition comprising diesel fuel/crude oil with a fuel additive composition comprising deposit control agent and cetane improver additive formulation.

The deposit control and cetane improver additive formulation comprising polyisobutylene succinimide and cetane improver is incorporated into fuel, more particularly diesel fuel and crude oil to obtain fuel composition.

Further, the invention provides a process for the preparation of fuel composition by blending diesel fuel/crude oil and combustion improver based deposit control additive formulation at an ambient temperature which is obtained by blending polyisobutylene succinimide, cetane improver and optionally dehazer, fluidizer oil, corrosion inhibitor, lubricity improver and antistatic agent at a temperature ranging between 20o C to 40o C.

This deposit control and cetane improver additive formulation is highly miscible with diesel fuel/crude oil at room temperature or slightly at higher temperature in case of heavy crude oil and is mixed with fuel in the storage tanks, road tanks, railway tanks etc.

In accordance with the present invention there is provided a synergistic combination of detergent/dispersant and cetane improver doped in diesel fuel and the fuel additive formulation comprising of polyisobutylene succinimide having average molecular weight ranging between 700 to 1200 and preferably about 1000; and an organic nitrate preferably alkyl nitrate.

According to the invention the organic nitrates are substituted or unsubstituted alkyl or cycloalkyl nitrates. The alkyl group may be either linear or branched. Few examples of nitrate compounds that may be optionally suitable for use in the present invention include methyl nitrate, ethyl nitrate, n-propyl nitrate, isopropyl nitrate, allyl nitrate, n-butyl-nitrate, isobutyl nitrate, sec-butyl nitrate, tert-butyl nitrate, n-amyl nitrate, isoamyl nitrate, 2-amyl nitrate, 3-amyl nitrate, tert-amyl nitrate, n-hexyl nitrate, 2ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate. Examples of primary hexyl nitrates would be n-hexyl nitrate, 2-ethylhexyl nitrate, 4-methyl-n-pentyl nitrate and the like. Organic nitrate preferably used in the present invention, is 2- ethyl hexyl nitrate (2-EHN).

The synergistic composition of detergent/ dispersant and cetane improver further comprising of optionally dehazer, corrosion inhibitor, diluent, lubricity improver, antistatic agent to provide a deposit control and as well as ignition accelerating additive formulation.

According to an embodiment of the present invention there is provided a fuel composition, comprising of diesel fuel/crude oil ranging from 99.90 to 99.99%, v/v and the fuel additive formulation (a synergistic combination of detergent and cetane improver) ranging from 0.01 to 0.10%, v/v.

Yet another embodiment of the present invention provides the fuel composition wherein the concentration of a synergistic combination detergent and cetane improver for deposit control additive formulations at various treat rates showed excellent performance in cetane number analysis test as per ASTM D613. Based on cetane number analysis data some of synergistic fuel additive formulations of the invention have exhibited good performance in Peugeot XUD 9 engine test. The additive doped fuel improves corrosion test as per NACE TM0172 which was carried out at 38 oC. The additive doped diesel fuel meets the Indian Specification IS 1460:2005 of automotive diesel fuel.

Further embodiment of the present invention provides a process for the preparation of fuel composition, said process comprising steps of:
a) Obtaining synergistic deposit control and ignition/cetane improving additive formulation by mixing polyisobutylene succinimide and cetane improver optionally dehazer, fluidizer oil, corrosion inhibitor, solvent, lubricity improver, antistatic agent, in a suitable container at a temperature ranging between 20oC to 40oC for a time period of up to 1-2 hours; and
b) Blending of the above additive formulation (a) with diesel fuel/crude oil at an ambient temperature or slightly at higher temperature in case of heavy crude oil.

It has been observed that the addition of a synergistic composition of detergent polyisobutylene succinimide and cetane improver such as an organic nitrate and optionally containing dehazer, fluidizers, corrosion inhibitor, lubricity improver, antistatic agent, significantly improves the deposit control characteristics of the said fuels.

The synergistic formulation of detergent polyisobutylene succinimide and cetane improver was used and fuel flow restriction was reduced from base value of 83% to 48% in diesel fuel at 250 ppm, v/v as per Peugeot XUD 9 engine test method.

According to the invention, the concentration of polyisobutylene succinimide in the diesel multifunctional additive package should be enough to control the deposits to get desired flow of the diesel in the injectors. This concentration is conveniently expressed in terms of weight percent of polyisobutylene succinimide based on the total weight of the compression ignition fuel composition. A preferred concentration is from about 30 to about 70 weight percent. A more preferred range is from about 30 to about 60 weight percent.

The amount of cetane improver should also be the amount which will achieve a level of auto-ignition sufficient to allow the operation of diesel/crude engines on the fuel composition of the present invention. A useful range is from about 10.0 weight percent to about 70.0 weight percent based on the total weight of additive composition. Preferred amount of cetane improver is between 30.0 weights percent to 60.0 weight percent.

The conventional blending equipment and techniques may be used in preparing the fuel composition of the present invention. In an embodiment of the invention a homogeneous blend of the foregoing active components is achieved by merely blending detergent polyisobutylene succinimide and 2-ethyl hexyl nitrate with low quantity of optional components like dehazer, fluidizer oil, corrosion inhibitor, anti-static agent to the present synergistic/ invented formulation in a determined proportion sufficient to reduce the deposit forming tendencies of the fuel. This is normally carried out at ambient temperature. In addition to the synergistic additive formulation of deposit control and cetane improver additives, the fuel composition may contain other additives which are well known to those skilled in the art.

The following non-limiting examples illustrate in details about the invention. However, they are not intended to be limiting the scope of present invention in any way.

Example 1
Preparation of Additive Formulations:
In order to study synergistic combination of detergent and cetane improver, various formulations of detergent, cetane improver and their combinations were prepared by using different combination of various ingredients by way of mixing the ingredients in a blending vessel at 30-40 oC with continuous stirring for 1-2 hr. Details are as follows:

Formulation – 1: A combination of polyisobutylene succinimide and diluent in the ratio 50: 50.
Formulation – 2: A combination of polyisobutylene succinimide and diluent in the ratio 35: 65.
Formulation – 3: A combination of 2-Ethyl Hexyl Nitrate and diluent in the ratio 50: 50.
Formulation – 4: A combination of polyisobutylene succinimide and 2-Ethyl Hexyl Nitrate in the ratio 50: 50.
Formulation – 5: A combination of polyisobutylene succinimide, dehazer and 2-Ethyl Hexyl Nitrate in the ratio 50: 2: 48.
Formulation – 6: A combination of polyisobutylene succinimide and 2-Ethyl Hexyl Nitrate in the ratio 30: 70.
Formulation – 7: A combination of polyisobutylene succinimide and 2-Ethyl Hexyl Nitrate in the ratio 35: 65.
Formulation – 8: A combination of polyisobutylene succinimide, 2-Ethyl Hexyl Nitrate, dehazer, corrosion inhibitor and diluent in the ratio 50:15:1:1:33.

Example 2
Evaluation Methodology
The complete evaluation of a synergistic combination of detergent and cetane improver was carried out in the diesel fuel by assessing the performance in the following parameters:

(a) Testing of combustion improver based deposit control additive formulations treated diesel fuel as per National Standard IS 1460: 2005: The regular diesel fuel meeting Indian Standard IS 1460: 2005 specification was used for the evaluation of deposit control and cetane improver additive formulation. The regular diesel fuel was doped with desired concentration of aforesaid synergistic composition of deposit control and ignition improver additive formulation. After the addition of deposit control and cetane improver additive formulation, the product was again tested as per IS 1460: 2005 specification to confirm that addition of deposit control and cetane improver additive formulation in the desired concentration in diesel fuel does not adversely affect diesel fuel properties.

(b) Evaluation of combustion improver based deposit control additive formulations for Rust/Corrosion Test: The above listed formulations were tested for rust/corrosion test. Rust or corrosion test is carried out to evaluate the ability of diesel fuel containing deposit control and cetane improver additive formulation to prevent rusting of ferrous parts when fuel comes in contact with water. Corrosion can lead to severe problems in storage tanks, pipelines and automobile fuel tanks. The particles of rust can also clog fuel lines, filters carburetor orifices or jets. The test evaluation procedure is based on NACE TM0172 standard test method at temperature 38oC for diesel fuels. A 300 ml of the unadditized/additized diesel fuel formulation was stirred at 1000 + 50 rpm with 30 ml of distilled water for 4 hrs using polished steel spindle conforming to grade 1018 of ASTM A-108 specifications. After the test the spindle is assessed for the corrosion and rating was given as per NACE protocol.

(c) Evaluation of combustion improver based deposit control additive formulations treated diesel fuel for Cetane Number analysis: The above listed formulations in Example 1 of deposit control detergent, cetane improver and their combinations were subjected to Cetane Number analysis as per ASTM D613 method.

(d) Evaluation of combustion improver based deposit control additive formulations for Nozzle Coking Test as per CEC F-23-01 on Peugeot XUD 9 engine: Nozzle coking test as per CEC F-23-01 protocol on Peugeot XUD 9 engine is the internationally accepted standard test for assessing the performance of diesel fuel containing deposit control additive which is synergistic combination of detergent and cetane improver formulation for injector nozzle coking propensity. These deposits are formed between the injector needle, the injector body and the needle seat, potentially causing unacceptable variations in engine performance. The results are expressed in terms of percentage injector airflow reduction at needle lift of 0.05, 0.1, 0.2, 0.3 and 0.4 mm of all nozzles. The performance criterion is a single value of the average percentage airflow reduction at 0.1 mm needle lift of all 4 nozzles.

(e) Evaluation of combustion improver based deposit control additive formulations treated diesel fuel/crude oil for fuel economy in main line engines: In order to test few synergistic additive formulations of polyisobutylene succinimide and cetane improver for fuel economy, diesel fuel/crude oil doped with additive formulation was subjected into main line engines. Initially the engines were run using neat diesel/crude oil without additive for generating base data and then diesel fuel/crude oil was doped with additive formulation and specific fuel consumption (SFC) was determined before and after additive addition.

Example 3
The diesel fuel meeting IS 1460: 2005 specification was doped with one of the above listed formulations @ 250 ppm and 1000 ppm, v/v treat rate and the treated samples were tested as per national standard specifications [IS 1460: 2005] to establish that the addition of these formulations do not have any deteriorating effect on the properties of diesel fuel. The test results are given in Table 1.

Table 1
Evaluation of additive formulations in diesel BS IV as per IS 1460: 2005 specification.
S. No. Characteristics Requirements of Bharat
Stage IV Base BS IV Diesel Base BS IV Diesel + formulation – 5 @ 1000 ppm, v/v Base BS IV Diesel + formulation – 5 @ 250 ppm, v/v
1. Acidity, inorganic Nil Nil Nil Nil
2 Acidity, total, mg of KOH/g, Max To report < 0.04 < 0.04 < 0.04
3. Ash, % by mass, max 0.01 < 0.001 < 0.001 < 0.001
4. Carbon residue (Ramsbottom) on 10 % residue, % by mass, Max 0.30

0.06 0.06 0.06
5. Cetane number, Min 51 53.9 57.2 55.7
6. Cetane index, Min 46 52.6 52.7 52.7
7. Pour point, Max, deg C
a) Winter
b) Summer
3
15

0

0

0
8. Copper strip corrosion for 3 h at 50 deg C Not worse than No. 1
No. 1
No.1
No.1
9. Distillation, % (v/v), recovered:
at 360 deg C, Min

95

95.5

95.5

95.5
10. Flash point
a) Abel, deg C, Min
b) Pensky Martens closed cup, deg C, Min
35
66
64.0
64.5
64.0
11. Kinematic viscosity,cSt, at 400C 2.0 to 4.5 2.960 2.962 2.962
12. Total contamination, mg/kg, Max 24 4 3 3
13. Density at 15 deg C, kg/m3 820-845 835.2 835.3 835.2
14. Total sulphur, ppm 50 < 10 < 10 < 10
15. Water content, mg/kg or ppm, Max 200 66 66 63
16. Cold filter plugging point (CFPP), Max, deg C
a) Winter
b) Summer

6
18

+ 1

+1

+1
17. Oxidation stability, g/m3, Max 25 6.0 6.0 6.0
18. Polycyclic aromatic hydrocarbon (PAH),
% By mass, Max
11
0.05
0.06
0.05
19. Lubricity corrected wear scar diameter (wsd 1.4) at 60 deg C, microns, Max 460 411 360 380

Example 4
Rust or Corrosion Test:
Diesel fuel doped with above mentioned additive formulations of deposit control detergent, cetane improver and combinations thereof as prepared in Example – 1, were tested as per NACE TM0172 and NACE rating was given to measure the ability of the doped diesel to prevent corrosion. The results are given in Table 2a & 2b.

Table 2a
Evaluation of different formulations of polyisobutylene succinimide, cetane improver and combinations thereof for rust test in BS III diesel.
S. No. Product Additive Concentration (ppm, v/v) NACE Rating
1 Base Diesel Euro III/BS III -- D
2 Base Diesel+ Formulation – 1 250 A
3 Base Diesel+ Formulation – 1 600 A
4 Base Diesel+ Formulation – 1 1000 A
5 Base Diesel+ Formulation – 2 250 A
6 Base Diesel+ Formulation – 2 1000 A
7 Base Diesel+ Formulation – 3 250 D
8 Base Diesel+ Formulation – 3 325 D
9 Base Diesel+ Formulation – 3 1000 C
10 Base Diesel+ Formulation – 3 1300 C
11 Base Diesel+ Formulation – 3 1400 C
12 Base Diesel+ Formulation – 4 250 A
13 Base Diesel+ Formulation – 4 1000 A
14 Base Diesel+ Formulation – 5 250 A
15 Base Diesel+ Formulation – 5 1000 A
16 Base Diesel+ Formulation – 6 250 A
17 Base Diesel+ Formulation – 6 1000 A
18 Base Diesel+ Formulation - 7 250 A
19 Base Diesel+ Formulation - 7 1000 A
20 Base Diesel+ Formulation - 8 250 A

Table 2b
Evaluation of different formulations of polyisobutylene succinimide, cetane improver and combinations thereof for rust test in BS IV diesel.
S. No. Product Additive Concentration (ppm, v/v) NACE Rating
1 Base Diesel Euro IV/BS IV -- C
2 Base Diesel+ Formulation – 1 250 A
3 Base Diesel+ Formulation – 1 600 A
4 Base Diesel+ Formulation – 1 1000 A
5 Base Diesel+ Formulation – 2 250 A
6 Base Diesel+ Formulation – 2 1000 A
7 Base Diesel+ Formulation – 3 250 C
8 Base Diesel+ Formulation – 3 325 B
9 Base Diesel+ Formulation – 3 1000 B
10 Base Diesel+ Formulation – 3 1300 B
11 Base Diesel+ Formulation – 3 1400 B
12 Base Diesel+ Formulation – 4 250 A
13 Base Diesel+ Formulation – 4 1000 A
14 Base Diesel+ Formulation – 5 250 A
15 Base Diesel+ Formulation – 5 1000 A
16 Base Diesel+ Formulation – 6 250 A
17 Base Diesel+ Formulation – 6 1000 A
18 Base Diesel+ Formulation - 7 250 A
19 Base Diesel+ Formulation - 7 1000 A
20 Base Diesel+ Formulation - 8 250 A

Example 5
The above listed formulations in Example 1 of deposit control detergent, cetane improver and their combinations were subjected to Cetane Number analysis as per ASTM D613 method. It has been observed that the combination of additives described herein to a diesel fuel, which comprise a minor/equal amount of poyisobutylene succinimide additive with a major/equal amount of cetane improver resulted in an increase of cetane number of the fuel to a level surpassing that would be expected based on single contribution attributed to each component individually. Thus the combination of alkyl nitrate and detergent/dispersant polymer constitutes an unexpectedly combination. The test results are given in Table 3.

Table 3
Evaluation of different formulations of polyisobutylene succinimide, cetane improver and combinations thereof for Cetane Number analysis in BS IV diesel.
S. No. Product Additive Concentration
(ppm, v/v) Cetane Number
1 Base Diesel Euro IV/BS IV -- 53.9
2 Base Diesel+ Formulation – 1 250 53.8
3 Base Diesel+ Formulation – 1 600 53.8
4 Base Diesel+ Formulation – 1 1000 53.9
5 Base Diesel+ Formulation – 2 250 54.4
6 Base Diesel+ Formulation – 2 1000 54.6
7 Base Diesel+ Formulation – 3 250 54.0
8 Base Diesel+ Formulation – 3 325 55.1
9 Base Diesel+ Formulation – 3 1000 55.4
10 Base Diesel+ Formulation – 3 1300 55.3
11 Base Diesel+ Formulation – 3 1400 55.3
12 Base Diesel+ Formulation – 4 250 55.6
13 Base Diesel+ Formulation – 4 1000 57.3
14 Base Diesel+ Formulation – 5 250 55.7
15 Base Diesel+ Formulation – 5 1000 57.2
16 Base Diesel+ Formulation – 6 250 54.9
17 Base Diesel+ Formulation – 6 1000 55.6
18 Base Diesel+ Formulation - 7 250 55.4
19 Base Diesel+ Formulation - 7 1000 56.9
20 Base Diesel+ Formulation - 8 250 54.0

Example 6
The above listed formulations in Example -1 of synergistic combination of detergent and cetane improver were evaluated for diesel nozzle coking test as per CEC F-23-01 on Peugeot XUD 9 engine. The test results are given in Table 4.

Table 4
Test results of synergistic formulations subjected to Peugeot XUD 9 engine.
S. No. Formulation Treat Rate
(ppm, v/v) % Nozzle Fouling
1 Reference Fuel - 83/84
2 Reference Fuel + Formulation -5 250 48
3 Reference Fuel + Formulation -7 250 48
4 Reference Fuel + Formulation -8 250 50

Example 7
One of the above listed formulations of synergistic combination of detergent and cetane improver was doped in BS III diesel fuel and subjected into two main line diesel engines for fuel economy. A cumulative 0.8% to 7.8% improvement in specific fuel consumption (SFC) was recorded at various loads. The SFC improvements results of both the main line engines are given in Table 5.

Table 5
Following tables shows the Specific fuel consumption (SFC) at various loads obtained before & after additive (formulation -5) dosing in MP1 and MP3 main line engines run on diesel fuel.

Main line engine MP1
Load Range Pre-additive Post-additive SFC improvement (%)
Weighted SFC value Weighted SFC value
50-55 202.14 186.32 7.82
65-69 181.28 173.93 4.05
75-79 177.94 176.45 0.84
80-84 173.16 171.01 1.24

Main line engine MP3
Load Range Pre-additive Post-additive SFC improvement (%)
Weighted SFC value Weighted SFC value
50-55 180.51 177 1.94
65-69 171.21 168.93 1.33
85-90 155.44 152.89 1.64

Another formulation of synergistic combination of detergent and cetane improver was blended in crude oil and fed to three mainline engines for fuel economy. Improvement in the specific fuel consumption (SFC) of crude oil was obtained in the range of 0.7 % to 5.3% at various load conditions. The SFC improvements data of crude oil run main line engines are given in Table 6.

Table 6
Following tables shows the Specific fuel consumption (SFC) at various loads obtained before & after additive (formulation -4) dosing in MP1, MP3 and MP4 main line engines run on crude oil.

Main line engine MP-1.
Load Range Pre-additive Post-additive SFC improvement (%)
Weighted SFC value Weighted SFC value
60-65 147 145 1.36
65-70 141 140 0.71
70-75 134 134 0.00
75-80 131 129 1.53
80-85 117 116 0.85

Main line engine MP-3
Load Range Pre-additive Post-additive SFC improvement (%)
Weighted SFC value Weighted SFC value
50-55 229 227 0.87
55-60 226 218 3.54
60-65 200 193 3.50
65-70 185 178 3.78
75-80 156 153 1.92

Main line engine MP-4

Load Range Pre-additive Post-additive SFC improvement (%)
Weighted SFC value Weighted SFC value
60-65 165 162 1.82
65-70 151 143 5.30
70-75 140 137 2.14

Table 7
Following table shows the Engine test data (Peugeot XUD 9) of various formulations:

S. No. Product Treat rate,
v/v % Fouling in XUD 9 engine test
1 Reference fuel -- 80-90
2 Reference + 2EHN 250 ppm 80
3 Reference + D1(PIBSI detergent) 250 ppm 72
4 Reference + D2 (Mannich base Detergent) 250 ppm 78
5 Reference + (D1+ D2), 3.3:1 250 ppm 62
6 Reference + (D1+ D2), 3.3:1 250 ppm 69
7 Reference + (D1+2EHN, 1:1) 250 ppm 48
8 Reference + (D2+2EHN, 1:1) 250 ppm 76
9 Reference + ( D1+2EHN in 1:2) 250 ppm 48
10 Reference + ( D1+2EHN in 3:1) 250 ppm 50
11 Reference + ( D1+2EHN in 1:2.3) 250 ppm 77

ADVANTAGES

1. The present invention provides an additive which improves the combustibility of fuel and reduces engine deposits.

2. The present invention provides an economic fuel with improved combustibility.

3. The present invention provides a combustion process with improved combustion of the fuel.
,CLAIMS:We Claim:
1. An additive composition to improve fuel combustion and reduce engine deposits, wherein the composition comprises a detergent and a cetane improver in a ratio of 1:0.3 to 1:2.

2. The additive as claimed in claim 1, wherein the detergent is polyisobutylene succinimide.

3. The additive as claimed in claim 2, wherein polyisobutylene succinimide is having an average molecular weight of 700 to 1200.

4. The additive as claimed in claim 1, wherein the cetane improver is 2-Ethyl Hexyl Nitrate.

5. The additive as claimed in claim 1, wherein the additive optionally comprises a dehazer, corrosion inhibitor, lubricity improver, antistatic agent, diluent or a mixture thereof.

6. The additive composition as claimed in claim 5, wherein a mixture comprising dehazer, corrosion inhibitor, lubricity improver, diluent and antistatic agent can be present to an extent of about 50 wt% of the additive composition.

7. The additive as claimed in claim 1, wherein the amount of the additive in the fuel composition is in the range of 0.01 to 0.10 % v/v.

8. A process for the preparation of additive composition to improve combustion and reduce engine deposits, wherein the process comprises blending a detergent and a cetane improver in a ratio of 1:0.3 to 1:2 at a temperature ranging between 20 to 40 ° C for a period of 1-2 hours.

9. The process as claimed in claim 7, wherein the detergent is polyisobutylene succinimide.

10. The process as claimed in claim 7, wherein the cetane improver is 2-Ethyl Hexyl Nitrate.

11. A fuel composition comprising a base fuel having boiling point in the range of 150o to 370oC or crude oil having boiling point in the range of 0o to 900oC, a detergent and a cetane improver in a ratio of 1:0.3 to 1:2, wherein an amount of the detergent and cetane improver in the base fuel or crude oil is in the range of 0.01 to 0.10 % v/v.

12. A process for preparing a fuel, comprising mixing base fuel having boiling point in the range of 150o to 370oC or crude oil having boiling point in the range of 0o to 900oC with a detergent and a cetane improver, wherein the ratio of detergent and a cetane improver is in the range of 1:0.3 to 1:2 and amount of the detergent and cetane improver in the base fuel or crude oil is in the range of 0.01 to 0.10 % v/v and wherein the mixing is performed at a temperature ranging between 20oC to 40oC for a time period in the range of 1 to 2 hours.

13. A process of combustion comprising:
a. providing a fuel composition to a combustion chamber; and
b. providing conditions suitable for combustion of the fuel composition in the combustion chamber;
wherein the fuel composition comprises a base fuel having boiling point in the range of 150o to 370oC or crude oil having boiling point in the range of 0o to 900oC and an additive composition comprising a detergent and a cetane improver in a ratio of 1:0.3 to 1:2, and wherein an amount of the additive in the base fuel or crude oil is in the range of 0.01 to 0.10 % v/v.