Diesel fuel additive providing clean up detergency of fuel injectors

Abstract: A diesel fuel composition comprising a major portion of a middle distillate fuel oil and a minor portion of a diesel fuel detergent which comprises the reaction product of: (a) a 4-alkyl-2-morpholine represented by the formula: in which R¹ represents alkyl having 1 to 10 carbon atoms, and (b) an alkylphenoxypolyoxyalkylene amine represented by the formula: in which R² represents a hydrocarbyl radical having 4 to 30 carbon atoms, x is 4 to 50, and R³ is methyl or a mixture of hydrogen and methyl, can be used in diesel engines and acts to remove deposits from the injectors of the engines.

Description: This invention relates to diesel fuel and, more particularly, to a diesel fuel composition containing a detergent additive which actively cleans deposits from dirty diesel fuel injectors. Diesel fuel impurities can arise from a variety of sources. They can form during refining or they can develop as a result of oxidation occurring during storage. Such impurities can be either soluble or insoluble materials having higher molecular weights and boiling points than the fuel, and which manifest themselves in the engine as coloured deposits or gums. Impurities can also be introduced into the fuel from corrosion of storage vessels during handling or during storage. Impurities can even take the form of other additives intentionally introduced by the manufacturer, to solve or prevent some particular problem, or improve the fuel itself, for example, anti-oxidants or rust preventatives. Regardless of the source, any of these impurities can cause deposits to form in the fuel system of compression ignition engines, and, in particular, in the fuel injectors. These deposits coat or adhere to injector parts and cause injector sticking, injector tip fuel metering passage fouling, nozzle hole plugging, leakage past critical surfaces, and delayed injection (and, hence, delayed start of combustion). These problems, in turn, result in significantly increased engine noise, smoke emissions, misfiring, low temperature or cold start problems, idle roughness, and decreased power output and fuel economy. It is believed that these engine problems are the result of long ignition delays, significantly contributed to by deposits, causing an excessively rapid pressure rise in the cylinder once combustion does occur. Recent evidence suggests that the long delay provides the time for certain chemical reactions to take place in the atomized fuel charge before ignition, resulting in products which burn exceedingly rapidly once combustion begins, thereby causing the undesirable rapid pressure rise, and the resultant problems. It would therefore be desirable to prevent the deposits caused by impurities or to remove such deposits once they have formed. The present invention provides a diesel fuel composition which contains a detergent additive which is effective to remove deposits from dirty diesel fuel injectors and to keep these injectors clean. The present invention provides a diesel fuel composition comprising a major portion of a middle distillate fuel oil and a minor portion of a diesel fuel detergent characterised in that the detergent comprises the reaction product of: (a) a 4-alkyl-2-morpholine represented by the formula: in which R 1 represents alkyl having 1 to 10 carbon atoms, and (b) an alkylphenoxypolyoxyalkylene amine represented by the formula: in which R 2 represents a hydrocarbyl radical having 4 to 30 carbon atoms, x is 4 to 50, and R 3 is methyl or a mixture of hydrogen and methyl. The present invention also provides a method for cleaning deposits from diesel engine fuel injectors comprising operating the diesel engine using a fuel composition as defined above. Our prior Application EP-A-0 574 203, which falls within the state of the art according to Article 54(3) EPC, discloses the production of the above-identified reaction products, and the use of the reaction products in gasoline for i.c. engines. We have discovered that the additive compounds are effective as detergents to clean deposits from dirty diesel engine fuel injectors. Unexpectedly, this class of detergent additives has been found to be effective at relatively low concentrations in diesel fuel. The 4-alkyl-2-morpholinone has the formula: in which R 1 is alkyl having from 1 to 10 carbon atoms, preferably from 1 to 4 carbon atoms, and most preferably from 1 to 3 carbon atoms. Specific compounds which fall within the scope of this formula include 4-methyl-2-morpholinone, 4-ethyl-2-morpholinone and 4-isopropyl-2-morpholinone. Of these compounds, 4-methyl-2-morpholinone is particularly preferred. These compounds can be made by any suitable means, see, for example, US-A-3073822. The alkylphenoxypolyoxyalkylene amine reactant has the formula: in which R 2 is a hydrocarbyl radical having 4 to 30 carbon atoms, x is 4 to 50, and R 3 is methyl or a mixture of hydrogen and methyl. Preferably, R 2 is a monovalent aliphatic radical having from 6 to 24 carbon atoms, more preferably 8 to 20 carbon atoms, and most preferably 9 to 18 carbon atoms. Preferably, x is 6 to 30, more preferably 6 to 20, and most preferably 10 to 20. The alkylphenoxypolyoxyalkylene amine reactant contains an internal group having the formula: Preferably R 3 is methyl, such that the internal group is derived from propylene oxide. R 3 , however, can be a mixture of hydrogen and methyl such that the internal group is derived from a mixture of propylene oxide and ethylene oxide, which can form either a random or block copolymer. When the internal group is derived from both propylene oxide and ethylene oxide, the ratio of propylene oxide : ethylene oxide may be from 2:3 to 999:1, and more preferably from 7:3 to 999:1. The 4-alkyl-2-morpholinone and the alkylphenoxypolyoxyalkylene amine are generally reacted in about a 1:1 mole ratio. While other mole ratios can be used, no significant advantage is realized in departing from a substantially equimolar reaction ratio. The reactants can be reacted at a temperature from room temperature to 130°C, and reaction time will depend upon reaction temperature. For example, at 130°C, the reaction will take from 1 to 4 hours, while at 30°C, the reaction will take from 1 to 30 hours. Preferably, the reaction is conducted at about 130°C for approximately 2 hours. The reaction product used according to the invention can be represented by the formula: wherein R 1 , R 2 , R 3 and x have the definitions given above. The following examples are provided to illustrate the preparation of the additive of the invention. EXAMPLE I A. Preparation of Propylene Oxide Adduct of Nonyl Phenol 6.8 Kg of nonyl phenol and 226.8 grams of 45 percent aqueous potassium hydroxide were charged into a 40 litre reactor which was then purged with pre-purified nitrogen. The reactor was heated to 110°C, while maintaining a nitrogen purge, and the initiator potassium hydroxide was dried to a water content of less than 0.15 percent using both vacuum and nitrogen stripping. 13.5 moles of propylene oxide (24.2 Kg) were then reacted at 110-115°C at 0.51 MPa over an 8.5 hour period. The reaction mixture was then digested for two hours to an equilibrium pressure and purged with nitrogen for 15 minutes. The alkaline product was then neutralized at 95°C by stirring for two hours with 612 grams of Magnesol 30/40™ adsorbent which was added in an aqueous slurry. Di-t-butyl p-cresol (9.3 grams) was then added to stabilize the product against oxidation. The neutralized product was then vacuum stripped to a minimum pressure at 110°C, nitrogen stripped, and filtered. Properties of the finished product are given in Table 1 below. Properties Acid no., mg KOH/g 0.001 Hydroxyl no. mg KOH/g 59.2 Unsaturation, meg/g 0.036 Water, wt.% 0.04 pH in 10:6 isopropanol-water 8.3 Color, Pt-Co 50 Sodium, ppm 0.5 Potassium, ppm 3.5 Viscosity, 77°F, µ 123 B. Preparation of Nonylphenoxypolyoxypropylene Amine 454g per hour of the product of Example 1A, 1.0 454g per hour of ammonia and 50 litres per hour of hydrogen were added to a tubular reactor filled with 1250 cm 3 of a nickel catalyst. The reactor conditions were 13.9 MPa and 210°C. The crude reactor effluent was charged into a clean dry kettle, then nitrogen stripped to 75°C and then placed under a vacuum and heated to 100°C. The product had the following analysis: meq/gram Total acetylated 1.09 Total amine 1.05 Primary amine 1.05 C. Preparation of the Reaction Product of 4-Methyl-2-Morpholinone and Nonylphenoxypolyoxypropylene Amine The following were charged into a 2-litre, three-necked flask equipped with a thermometer, stirrer, and nitrogen outlet: 1099.8 grams of nonylphenoxypolyoxypropylene amine (the product of Example 1B) and 132.8 grams of 4-methyl-2-morpholinone. The mixture was heated at 130°C for two hours. The resulting product had the following analysis: meq/gram Total acetylated 1.09 Total amine 1.002 and can be represented by the formula: EXAMPLE II Example I was repeated, except that 7.5 moles of propylene oxide, instead of 13.5 moles, were reacted with nonylphenol in making Preparation A. EXAMPLE III Example I was repeated, except that 19.5 moles of propylene oxide, instead of 13.5 moles, were reacted with nonylphenol in making Preparation A. EXAMPLE IV Example I was repeated, except that the morpholinone reacted was 4-isopropyl-2-morpholinone instead of 4-methyl-2-morpholinone. EXAMPLE V Example I was repeated, except that 13.8 moles of a mixture of ethylene oxide and propylene oxide, instead of 13.5 moles of propylene oxide, were reacted with nonylphenol in making Preparation A. Diesel Fuel In its broadest embodiment, the diesel fuel composition of the present invention comprises a major portion of a middle distillate fuel oil boiling in the range from 170 to 345°C, and a sufficient minor proportion of the diesel fuel detergent used according to the present invention to remove deposits from dirty diesel fuel injectors. The amount of the diesel fuel detergent which is effective to clean dirty diesel fuel injectors can easily be determined by those in the petroleum industry. Of course, it is most cost effective to use as little of the additive as will be effective to clean deposits from dirty fuel injectors. One method suitable for this determination is the injector clean up test detailed below. The diesel fuel detergent of the invention is effective at low concentrations of between 10 parts per thousand barrels of base fuel stock (PTB) (33 parts per million(ppm)), preferably 50 PTB (165 ppm), more preferably 75 PTB (248 ppm) and most preferably 90 PTB (297 ppm), and 300 PTB (990 ppm), preferably 150 PTB (495 ppm), more preferably 125 PTB (247 ppm) and most preferably 100 PTB (330ppm). The additives used according to the present invention may be added to diesel fuel by any means known in the art for adding small quantities of additives to a base fuel. The additive used according to the present invention can advantageously be employed in a remedial method for cleaning deposits from dirty diesel fuel injectors. In accordance with this method, a diesel engine with dirty fuel injectors is operated using a fuel containing the diesel fuel additive, in the amounts described above. The engine is preferably operated in this manner for at least 3 hours. The diesel fuel detergent additives used according to the present invention are effective in very small concentrations and, therefore, for consumer end use it is desirable to package them in dilute form. Thus, a concentrate of the additives of the present invention can be provided comprising a diluent e.g., xylene, toluene, kerosine or heavier oil, including either diesel fuel or lubricating fractions such as SNO 600 or SNO 2000, and 1 to 50 wt. % of the additive. An additive of the present invention, represented by the formula was evaluated at 100 PTB (330 ppm) in a typical diesel fuel using the Daimler Benz OM-616 Engine test, as compared to the same fuel without the additive. The diesel fuel was a typical middle distillate having a boiling point range from 170 to 345°C and a sulphur content of 0.17%. Daimler Benz OM-616 Engine The Daimler Benz OM-616 Engine is equipped with pintle type injectors and is typically used in light duty vehicles. The engine has the following specifications: Daimler Benz OM-616 Engine No. of Cylinders 4 Bore 79.0 mm Stroke 61.0 mm Nozzle Opening Pressure 11.6-12.7 MPa (115-125 atms) Injection Timing 24° BTDC Description of Test New nozzles blown through with air, using a nozzle flow testing rig to ISO 4010 standards. The nozzles are assembled, set to the correct opening pressure and then fitted to the engine. The engine is then operated for three hours to form deposits on the injectors. During the test, the engine is operated under the following conditions: Test Conditions Engine Speed 4000 rpm Engine Power 12 kW Test Duration 3 hours Air Inlet Temperature 18 - 25°C Coolant Outlet Temperature 85°C Oil Sump Temperature 110 - 115°C At the end of the three hour period, the injectors are removed and are again blown through. The injectors are reassembled, reinstalled in the engine and run for three more hours using an additive-treated fuel to clean-up the deposits. The nozzles are again blown through at the end of the clean-up test. The results are expressed in terms of percentage of clean engine flow. For each cylinder, a mathematical mean of the flow at lift points 0.1mm, 0.2mm, 0.3mm and 0.4mm was calculated. The figure reported in Table 2 below is the average of the results for the four cylinders of the engine. Run 1 2 Fuel base fuel plus additive of the present invention base fuel with no additive Percentage of clean engine flow rate 43.2% 26% These results indicate that after the engine was run with fuel containing no additive, the injectors passed only 26% of the air that the clean injectors passed. On the other hand, after the thus contaminated engine was run with a fuel composition according to the present invention, the injectors passed 43.2% of the air that the clean injectors passed. Thus, the additive used according to the present invention showed excellent clean-up detergency: the injectors cleaned by the process of the present invention passed 66% more air, measured as a percentage of the flow of the injectors which were run with base fuel containing no additives.

Claims: A diesel fuel composition comprising a major portion of a middle distillate fuel oil and a minor portion of a diesel fuel detergent characterised in that the detergent comprises the reaction product of: (a) a 4-alkyl-2-morpholine represented by the formula: in which R 1 represents alkyl having 1 to 10 carbon atoms, and (b) an alkylphenoxypolyoxyalkylene amine represented by the formula: in which R 2 represents a hydrocarbyl radical having 4 to 30 carbon atoms, x is 4 to 50, and R 3 is methyl or a mixture of hydrogen and methyl. A composition according to Claim 1 characterised in that R 1 represents methyl, ethyl or isopropyl. A composition according to Claim 1 or 2 characterised in that R 2 has 6 to 24 carbon atoms. A composition according to any one of Claims 1 to 3 characterised in that x is 6 to 30. A composition according to any one of Claims 1 to 4 characterised in that R 3 is methyl. A composition according to any one of Claims 1 to 4 characterised in that R 3 is a mixture of methyl and hydrogen such that the internal alkylene oxide group of the formula comprises a mixture of propylene oxide and ethylene oxide in a molar ration of 2:3 to 999:1. A composition according to any one of Claims 1 to 6 characterised in that the detergent is present in an amount of 33 to 990 ppm (10 to 300 PTB). A method for cleaning deposits from diesel engine fuel injectors comprising operating the diesel engine using a fuel composition according to any one of Claims 1 to 7. A method according to Claim 8 characterised in that the diesel engine is operated for a least 3 hours.

Inventors: HERBSTMAN SHELDON, HERBSTMAN, SHELDON
Applicants: TEXACO DEVELOPMENT CORP, TEXACO DEVELOPMENT CORPORATION
Application year: 1993
Main classification: C10L1
IPC codes: C10L1, F02B3, C10L10