JP2011521062A - Fuel composition - Google Patents

Abstract

  Use of a Fischer-Tropsch derived fuel component in a fuel composition that reduces the accumulation rate of the acidic component of a lubricating fluid present in an internal combustion engine that is or is intended to operate with the fuel composition Use for. Fischer-Tropsch derived fuel components also reduce the oxidation and / or nitration rate of the lubricating fluid, reduce the acid-induced engine wear rate in the engine, and / or reduce the frequency of lubricating fluid replacement in the engine Can be used for The fuel composition is preferably a diesel fuel composition.

Description

  The present invention relates to the use of certain fuel components in fuel compositions to reduce the acid accumulation rate of engine lubricants.

  It is known to use lubricating fluids in engines to reduce friction between moving parts and thereby reduce wear of moving parts.

  However, during engine use, the properties of the lubricant over time can degrade this performance and gradually degrade to the point that it must be replaced. Many of the lubricant alterations are due to impurities sent from the combustion chamber to the sump. For example, soot can accumulate in the lubricant and as it increases the viscosity of the fluid until the fluid can no longer function effectively. Soot particles can aggregate and become abrasive, which also contributes to engine wear.

  Lubricants can also be degraded by oxidation. This increases the carboxylic acid content of the lubricant. In addition, as nitric oxide from the engine dissolves in the lubricant, typically as nitrates, and nitric acid and nitrous acid, lubricant nitration can occur, which also increases overall acidity Bring. Acidic components tend to be corrosive and can therefore cause further engine wear.

  Lubricants are typically formulated with a base “reservoir” to neutralize acidic components that accumulate in the lubricant during use, but increase in acid content too rapidly, or too quickly The reduction in base content is clearly undesirable because it can affect engine corrosion.

  Furthermore, both oxidation and nitration can result in the formation of sludge precursor products. Oil oxidation results in highly viscous agglomerated hydrocarbons that adhere to internal engine surfaces as “sludge” and can deposit in low oil flow areas. This reduces the effective oil capacity and results in increased wear. Therefore, sludge accumulation in the lubricant can also reduce this performance and shorten the interval between lubricant changes.

  Discharging and replacing engine lubricant can be costly and time consuming. Accordingly, it is desirable to be able to reduce the rate of lubricant degradation and thereby increase the interval between lubricant changes. It would also be desirable to be able to achieve these improvements without having to change the engine itself, regardless of the nature of the lubricating fluid.

  According to a first aspect of the invention, the use of a Fischer-Tropsch derived fuel component in an internal combustion engine is present in the engine while operating with this fuel component or a fuel composition containing this component. Use is provided for reducing the accumulation rate of acidic components of a lubricating fluid.

  According to a second aspect, the present invention is the use of a Fischer-Tropsch derived fuel component in a fuel composition, present in an internal combustion engine that is or is intended to operate with this fuel composition. Use for reducing the accumulation rate of acidic components of a lubricating fluid is provided.

  The acidic component can in particular be derived from oxidation and / or nitration of the lubricating fluid. The acidic component can be selected from, for example, carboxylic acid, nitric acid and nitrous acid, and mixtures thereof. The “accumulation rate” of such components is the rate at which their concentration changes (rises) in the lubricating fluid. In some cases, the present invention is used to reduce the rate of accumulation of acidic components other than those present in soot, eg, soot formed by incomplete combustion.

  Thus, according to a third aspect of the present invention, the use of a Fischer-Tropsch derived fuel component in an internal combustion engine, during operation with this fuel composition, and oxidation and / or lubrication of the lubricating fluid present in the engine. Or use is provided to reduce the nitration rate.

  According to a fourth aspect, the present invention is the use of a Fischer-Tropsch derived fuel component in a fuel composition, present in an internal combustion engine that is or is intended to operate with this fuel composition. Use for reducing the oxidation and / or nitration rate of a lubricating fluid is provided.

  In this context, the internal combustion engine can be, for example, a spark ignition (“gasoline”) engine or a compression ignition (“diesel”) engine. In one embodiment of the invention, the engine is a diesel engine.

  The fuel composition can be any fuel composition suitable for use in an internal combustion engine. For example, it can be a gasoline, petrol fuel composition or a diesel fuel composition. In addition to the Fischer-Tropsch derived fuel component, the fuel composition may contain one or more (typically diesel) base fuels and / or one or more non-Fischer-Tropsch derived fuel components.

  Fischer-Tropsch derived fuel component is 1% v / v or more, or 2 or 5 or 10% v / v or more, such as 50% v / v or more, or 80 or 90% v / v, relative to the total fuel composition. It can be used at a concentration of v or higher. This concentration in the total composition can be up to 100% v / v, such as up to 99.8% v / v, or up to 99.5% v / v or 99% v / v.

  In one embodiment of the present invention, the fuel composition mainly comprises a Fischer-Tropsch derived fuel component, for example, a Fischer-Tropsch derived fuel component of 98% v / v or more, optionally together with one or more fuel additives. Or 99% v / v or more, or 99.5 or 99.8% v / v or more.

  Accordingly, the present invention is also the use of a Fischer-Tropsch derived fuel component as a fuel composition in an internal combustion engine, present in the engine while operating with this fuel composition (ie, Fischer-Tropsch derived fuel component). Also included is the use to reduce the acidic component accumulation rate and / or oxidation or nitration rate of the lubricating fluid.

  In one embodiment of the present invention, the fuel composition in which the Fischer-Tropsch derived component is used is a diesel fuel composition suitable for and / or adapted for and / or intended for use in a diesel engine. It is a thing. Thus, the fuel composition can include one or more diesel-based fuels, typically light oils, which can be non-Fischer-Tropsch derived (eg, petroleum derived “fraction”) fuels. For example, it can be an automobile diesel fuel composition for use in driving an automobile vehicle.

  The diesel fuel composition prepared in accordance with the present invention can contain one or more conventional diesel fuel compositions in addition to the Fischer-Tropsch derived fuel component. Such components typically include liquid hydrocarbon middle distillate fuel oils such as petroleum-derived gas oils. In general, such fuel components can be of organic or synthetic origin, suitably obtained by distilling the desired range of fractions from crude oil. These fuel components typically have boiling points of 150-410 ° C., or 170-370 ° C. within the normal diesel range, depending on the grade and application. Typically, the fuel composition includes one or more cracked products obtained by splitting heavy hydrocarbons.

  Petroleum-derived light oil can be obtained, for example, by refining a crude petroleum source and, if necessary, treating it (hydrogen). Petroleum-derived gas oil can be a single gas oil stream obtained from such a refining process, or a blend of several light oil fractions obtained from refining processes by various processing routes. Examples of such gas oil fractions were obtained with straight run gas oil, vacuum gas oil, gas oil obtained in the pyrolysis process, light and heavy circulating oil obtained in fluid catalytic cracking equipment, and hydrogenolysis cracker. Light oil. If desired, the petroleum-derived gas oil can include some petroleum-derived kerosene fraction.

  Such light oil can be processed in a hydrodesulfurization (HDS) unit to reduce the sulfur content to a level suitable for incorporation into a diesel fuel composition.

The diesel fuel component contained in the composition prepared according to the present invention typically has a density at 15 ° C. of 750 to 900 kg / m ³ , preferably 800 to 860 kg / m ³ (ASTM D-4052 or EN ISO 3675), And / or having a kinematic viscosity (VK40) at 40 ° C. of 1.5 to 6.0 centistokes (mm ² / s) (ASTM D-445 or EN ISO 3104).

  Reference herein to viscosity is intended to mean kinematic viscosity unless otherwise indicated.

  In a diesel fuel composition prepared in accordance with the present invention, the base fuel itself can comprise a mixture of two or more of the above types of diesel fuel components. Is this a so-called “biodiesel” fuel component, such as vegetable oil, hydrogenated vegetable oil, or vegetable oil derivative (eg, fatty acid ester, especially fatty acid methyl ester), or other oxygenates such as acids, ketones, or esters? Or it can contain this component. Such components are not necessarily derived from living organisms.

  A fuel composition prepared according to the present invention, specifically a diesel fuel, more specifically an automotive diesel fuel, suitably has a sulfur of 5000 ppmw (parts per million by weight) or less, typically 2000 to 5000 ppmw, or Contains 1000 to 2000 ppmw, or 1000 ppmw. The composition can be, for example, a low or very low sulfur fuel, or a sulfur-free fuel, for example containing up to 500 ppmw sulfur, preferably 350 ppmw or less, most preferably 100 or 50, or even 10 ppmw or less.

  In the context of the present invention, the term “Fischer-Tropsch derived” means that a material is or is derived from a synthetic product of a Fischer-Tropsch condensation process. The term “from non-Fischer-Tropsch” can be interpreted accordingly. Accordingly, the Fischer-Tropsch derived fuel or fuel component, except for the added hydrogen, becomes a hydrocarbon stream, with a substantial portion derived directly or indirectly from the Fischer-Tropsch condensation process.

  Fischer-Tropsch derived products can also be referred to as GTL products.

Fischer-Tropsch reactions are typically conducted in the presence of a suitable catalyst, typically at elevated temperatures (eg, 125 to 300 ° C., preferably 175 to 250 ° C.) and / or high pressure (eg, 0.5 to 10 MPa, preferably 1. 2 to 5 MPa) to convert carbon monoxide and hydrogen to longer chain hydrocarbons, usually paraffinic hydrocarbons:
n (CO + 2H ₂ ) = (— CH ₂ —) _n + nH ₂ O + heat If desired, hydrogen: carbon monoxide ratios other than 2: 1 can be used.

  Carbon monoxide and hydrogen itself can be derived from organic, inorganic, natural or synthetic sources, typically from natural gas or organic derived methane.

  Fischer-Tropsch derived fuel components useful in the present invention can be obtained directly from purification or Fischer-Tropsch reactions, or, for example, fractionation or hydrotreating a refined or synthesized product to fractionate or hydrogenate production. It can also be obtained indirectly by producing things. Hydroprocessing improves cold flow properties by hydrocracking to adjust the boiling range (see, for example, GB-B-2077289 and EP-A-0147873) and / or increasing the proportion of branched paraffins. Possible hydroisomerization. EP-A-0583836 first subjecting the Fischer-Tropsch synthesis product to hydroconversion under conditions such that it is not substantially subject to isomerization or hydrocracking (this ensures that the olefinic and oxygen-containing components are hydrogenated). And then hydroconverting at least a portion of the resulting product under conditions such that hydrocracking and isomerization occurs to obtain a substantially paraffinic hydrocarbon fuel. A step hydrotreating process is described. The desired fraction, typically a light oil fraction, can then be isolated, for example, by distillation.

  Using other synthetic post-treatments such as polymerization, alkylation, distillation, cracking-decarboxylation, isomerization, and hydrogenation reforming, for example as described in US-A-4125556 and US-A-4478955 The properties of the Fischer-Tropsch condensation product can be modified.

  A typical catalyst for Fischer-Tropsch synthesis of paraffinic hydrocarbons contains a Group VIII metal of the Periodic Table of Elements, particularly ruthenium, iron, cobalt, or nickel, as the catalytically active component. Such suitable catalysts are described, for example, in EP-A-0583836.

  An example of a Fischer-Tropsch-based method is Shell ™ “Gas-to-liquids” or “GTL” technology (formerly known as SMDS (Shell Middle Distillate Synthesis)). "The Shell Middle Distilination Synthesis Process", van der Burgt et al., 5th Synfuels Worldwide Symposium, Wastonton DC, et al, published in November 1985. (It is described in the publication of the title November 1989.) In the latter case, the preferred features of the hydroconversion process can be as disclosed in the literature, which is a heavy long-chain hydrocarbon that can later hydroconvert and fractionate natural gas. By conversion to (paraffin) wax, a middle distillate range product is produced.

  Thanks to the Fischer-Tropsch process, the Fischer-Tropsch derived fuel or fuel component is essentially free of sulfur and nitrogen or contains undetectable levels of sulfur and nitrogen. Compounds containing these heteroatoms tend to act as Fischer-Tropsch catalyst poisons and are therefore removed from the synthesis gas feed. This provides additional benefits to fuel compositions prepared according to the present invention.

  Generally speaking, Fischer-Tropsch derived hydrocarbon products have relatively low levels of polar components, particularly polar surfactants, compared to, for example, petroleum derived fuels. This may contribute to the improvement of the defoaming performance and defrosting performance. Such polar components can include, for example, oxygenates and sulfur and nitrogen containing compounds. Low levels of sulfur in Fischer-Tropsch derived products generally indicate low levels of both oxygenates and nitrogen-containing compounds because all are removed in the same process step.

  In addition, the commonly used Fischer-Tropsch process does not produce or substantially does not produce aromatic components.

  A Fischer-Tropsch derived fuel component for use in the present invention can be any suitable component derived from gas liquefaction synthesis (hereinafter GTL component) or a similar Fischer-Tropsch component that converts, for example, gas, biomass, or coal into a liquid. It can be any suitable component derived from Tropsch synthesis (hereinafter XTL component). The Fischer-Tropsch derived fuel component is preferably a GTL fuel component. This can be a BTL (biomass liquefaction) component. In general, suitable XTL components can be middle distillate fuel components selected from, for example, naphtha, kerosene, diesel, and gas oil fractions, as known in the art, such components are comprehensive Can be classified as synthetic process fuels or synthetic process oils. Preferably, the XTL component for use in the present invention is light oil.

  Fischer-Tropsch derived gas oils typically have a major component (eg, 95% v / v or more) having a boiling point within the typical diesel fuel (“light oil”) range, ie, about 150-400 ° C., or 170-370 ° C. It will contain. This component suitably has a 90% v / v distillation temperature of 300 to 370 ° C.

Fischer-Tropsch derived gas oil typically has a density at 15 ° C. (ASTM D-4052 or EN ISO 3675) of 0.76 to 0.79 g / cm ³ , a cetane number (ASTM D-613) of more than 70, suitably 74. To 85, VK40 (ASTM D-445 or EN ISO 3104) 2 to 4.5, preferably 2.5 to 4.0, more preferably 2.9 to 3.7 centistokes (mm ² / s), and sulfur The content (ASTM D-2622 or EN ISO 20846) is 5 mg / kg or less, preferably 2 mg / kg or less.

  In one embodiment, the Fischer-Tropsch derived gas oil used in the present invention is ideal, using a hydrogen / carbon monoxide ratio of less than 2.5, preferably less than 1.75, more preferably 0.4 to 1.5. Is a product prepared by a Fischer-Tropsch methane condensation reaction using a cobalt-containing catalyst. This product is obtained from a hydrocracked Fischer-Tropsch synthesis product (eg as described in GB-B-2077289 and / or EP-A-0147873), more preferably in EP-A-0583836 It can be the product of a two-stage hydroconversion process as described (see above). In the latter case, the preferred features of the hydroconversion process can be as disclosed in pages 4 to 6 of EP-A-0583836 and in the examples.

  Suitably, according to the present invention, the Fischer-Tropsch derived light oil is a paraffinic component of at least 70% w / w, preferably at least 80% w / w, more preferably at least 90 or 95 or 98% w / w, Most preferably it consists of at least 99 or 99.5 or even 99.8% w / w. The weight ratio of isoparaffin to normal paraffin is suitably 1: 1 or greater than 2: 1, for example 1: 1 to 10: 1, or 1: 1 to 5: 1. The actual value of this ratio will be determined in part by the hydroconversion process used to prepare light oil from the Fischer-Tropsch synthesis product.

  The olefin content of the Fischer-Tropsch derived light oil is suitably 0.5% w / w or less. This aromatic content is suitably 0.5% w / w or less.

  According to the present invention, a mixture of two or more Fischer-Tropsch derived fuel components can be used in a fuel composition and / or an internal combustion engine.

  In the context of the present invention, “use” of a Fischer-Tropsch derived fuel component in an internal combustion engine means introducing the Fischer-Tropsch derived fuel component into the engine, typically into the combustion chamber. Accordingly, the Fischer-Tropsch derived fuel can be introduced as part of a fuel composition containing one or more other fuel components and / or additives. This use includes operating the engine with such a fuel composition or a Fischer-Tropsch derived fuel component alone.

  “Use” of a Fischer-Tropsch derived fuel component in a fuel composition refers to a Fischer-Tropsch derived fuel component, typically one or more other fuel components (typically diesel base fuel) and optionally one. It is meant to be incorporated into the composition as a blend (ie, a physical mixture) with the above fuel additives. The Fischer-Tropsch derived fuel component is conveniently incorporated prior to introducing the composition into an internal combustion engine operated with the composition. Alternatively or additionally, this use may include operating an internal combustion engine with a fuel composition containing a Fischer-Tropsch derived fuel component, typically by introducing the composition into the engine's combustion chamber. it can.

  The “use” of the Fischer-Tropsch derived fuel component according to the present invention achieves one or more of the objectives described herein, in particular to reduce the accumulation rate of the acidic component of the lubricating fluid in an internal combustion engine, and / or Alternatively, supplying such components with fuel compositions and / or instructions for use in an internal combustion engine may be included to reduce the oxidation or nitration rate of the lubricating fluid.

  The Fischer-Tropsch derived fuel component itself can be provided as a component of a formulation suitable and / or intended for use as a fuel additive, in particular a diesel fuel additive, in which case Fischer-Tropsch derived The component depends on the accumulation rate of the acidic component of the lubricating fluid and / or the oxidation and / or nitration rate of such lubricating fluid in the internal combustion engine where the fuel composition is or is intended to be introduced. Can be added to such formulations for the purpose of influencing the fuel composition to which they are added.

  Thus, the Fischer-Tropsch derived fuel component can be incorporated into an additive formulation or package with one or more fuel additives. Fischer-Tropsch derived fuel component is selected, for example, from additive formulations, components containing detergents, anti-corrosive additives, esters, polyalphaolefins, long chain organic acids, amine or amide active centers, and mixtures thereof Can be combined with one or more of the added fuel additives. In particular, it can be combined with one or more so-called performance additives, which typically include at least a cleaning agent.

  The Fischer-Tropsch derived fuel component can be blended directly with one or more other components of the fuel composition, for example, in a refinery.

  A fuel composition prepared in accordance with the present invention, or a base fuel used in such a composition, may contain other components, such as one or more fuel additives.

  For example, in a refiner, when an additive is added (containing an additive), the fuel composition or component can be, for example, an antistatic agent, a pipeline resistance reducing agent, a flow improver (eg, an ethylene / vinyl acetate copolymer). Or acrylate / maleic anhydride copolymer), lubricating additives, antioxidants, and wax anti-settling agents in small amounts. Accordingly, the fuel composition has a small ratio (preferably 1% w / w or less, more preferably 0.5% w / w (5000 ppmw) or less, most preferably 0.2% w / w (2000 ppmw) or less). One or more fuel additives can be included.

  The fuel composition prepared according to the present invention may contain, for example, a cleaning agent. Detergent-containing fuel additives are known and are commercially available. Such additives can be added to the fuel at a level intended to reduce, remove, or delay the accumulation of engine sediment.

  Examples of detergents suitable for use in fuel additives for the purposes of the present invention include polyolefin substituted succinimides or succinamides of polyamines such as polyisobutylene succinimide or polyisobutylene amine succinamide, aliphatic amines, Mannich bases or Included are amines and polyolefins (eg, polyisobutylene) maleic anhydride. Succinimide dispersant additives are described, for example, in GB-A-960493, EP-A-0147240, EP-A-0482253, EP-A-0613938, EP-A-0557516, and WO-A-98 / 42808. Yes. Particularly preferred are polyolefin substituted succinimides such as polyisobutylene succinimide.

  Fuel additive mixtures that can be used in fuel compositions prepared in accordance with the present invention can contain other components in addition to the detergent. Examples of this, particularly for use in diesel fuel compositions, are lubricity enhancers, dehaze agents, such as alkoxylated phenol formaldehyde polymers, antifoam agents (eg, polyether modified polysiloxanes), ignition improvers. (Cetane improver) (for example, 2-ethylhexyl nitrate (EHN), cyclohexyl nitrate, di-tert-butyl peroxide, and those disclosed in US Pat. No. 4,208,190, column 2, line 27 to column 3, line 21), Rust inhibitor (eg, propane-1,2-diol half ester of tetrapropenyl succinic acid, or polyhydric alcohol ester of succinic acid derivative (succinic acid derivative contains 20 to 500 carbon atoms in at least one of the α carbon atoms) Containing unsubstituted or substituted aliphatic hydrocarbon groups.), Eg poly Pentaerythritol diester of sobutylene-substituted succinic acid), corrosion inhibitors, flavoring agents, antiwear additives, antioxidants (eg phenols such as 2,6-di-tert-butylphenol, or N, N′-di) Phenylenediamines such as -sec-butyl-p-phenylenediamine), metal deactivators, auxiliary agents, antistatic additives, low temperature fluidity improvers, viscosity improvers, and wax settling inhibitors.

Such fuel additive mixtures can contain lubricity enhancers, particularly when the fuel composition has a low (eg, 500 ppmw or less) sulfur content. In fuel compositions with additives, the lubricity enhancer is conveniently present at a concentration of less than 1000 ppmw, preferably 50 to 1000 ppmw, more preferably 70 to 1000 ppmw. Suitable commercially available lubricity enhancers include esters and acid based additives. Other lubricity enhancers are described in the patent literature, particularly for their use in low sulfur content diesel fuels, for example:
Danping Wei and H.H. A. Spikes' paper, "The Lubricity of Diesel Fuels", Wear, III (1986) 217-235,
WO-A-95 / 33805-Low temperature fluidity improver for enhancing lubricity of low sulfur fuel,
WO-A-94 / 17160-esters of certain carboxylic acids and alcohols (acids having from 2 to 50 carbon atoms, alcohols being used as fuel additives to reduce wear in diesel engine injectors Having one or more carbon atoms)), in particular glycerol monooleate and diisodecyl adipate,
US Pat. No. 5,490,864 as low-sulfur diesel fuel antiwear lubricant additive, certain dithiophosphoric acid diester-dialcohols, and WO-A-98 / 01516, especially in low sulfur diesel fuel Certain alkyl aromatic compounds having at least one carboxyl group bonded to an aromatic nucleus for imparting.

  It may be preferable for the fuel composition to contain an antifoaming agent, and combinations with rust inhibitors and / or corrosion inhibitors and / or lubricity enhancing additives are more preferred.

  Unless stated otherwise, the (active substance) concentration of each such additive component in a fuel composition with additives is preferably up to 10000 ppmw, more preferably 0.1 to 1000 ppmw, advantageously 0. It is in the range of 1 to 300 ppmw, for example 0.1 to 150 ppmw.

  The (active substance) concentration of any defogging agent in the fuel composition is preferably in the range of 0.1 to 20 ppmw, more preferably 1 to 15 ppmw, even more preferably 1 to 10 ppmw, advantageously 1 to 5 ppmw. . The (active substance) concentration of any ignition enhancer present will preferably be 2600 ppmw or less, more preferably 2000 ppmw or less, conveniently 300 to 1500 ppmw. The (active substance) concentration of any detergent in the fuel composition is preferably in the range of 5 to 1500 ppmw, more preferably 10 to 750 ppmw, and most preferably 20 to 500 ppmw.

  If desired, one or more additive components, such as those described above, can be co-mixed into the additive concentrate, preferably with an appropriate diluent, after which the additive concentrate is based. It can be dispersed in a fuel or fuel composition.

  In the case of a diesel fuel composition, for example, the fuel additive mixture typically contains a cleaning agent and a diesel fuel compatible diluent, optionally with the other components described above, which diluent oil Sold under the trademark "SHELLSOL" from Shell, polar solvents such as esters, and especially alcohols such as hexanol, 2-ethylhexanol, decanol, isotridecanol, and alcohol mixtures such as the trademark " Solvents such as those sold under "LINEVOL", in particular LINEVOL 79 alcohol, which is a mixture of C7-9 primary alcohols, or commercially available C12-14 alcohol mixtures.

  The total additive content in the fuel composition may suitably be from 0 to 10,000 ppmw, preferably less than 5000 ppmw.

  In this specification, the amount of ingredients (concentration,% v / v, ppmw,% w / w) is the amount of active substance, ie the amount excluding volatile solvent / diluent material.

  In the context of the present invention, the lubricating fluid is any lubricating fluid, typically oil, that is suitable for and / or adapted for use in an internal combustion engine, in particular a diesel engine. Can be.

  A typical lubricating fluid consists primarily of one or more base oils, which can be selected from either synthetic (lubricating) oils, mineral oils, natural oils, or mixtures thereof. Mineral oils include liquid petroleum, paraffinic, naphthenic, or mixed paraffinic / naphthenic solvent-treated or acid-treated mineral lubricants that are further refined by hydrofinishing and / or dewaxing. be able to. Synthetic base oils include Fischer-Tropsch derived base oils, as well as olefin oligomers (PAO), dibasic acid esters, polyol esters, and dewaxed waxy raffinates.

For use in an internal combustion engine, the base oil is suitably less than 1 wt.% Sulfur, preferably 0.1 wt.%, As determined by, for example, ASTM D-2622, D-4294, D-4927, or D-3120. % Is contained. The base oil suitably has a viscosity index measured according to ASTM D-2270 of greater than 80, preferably greater than 120. The base oil conveniently has a VK100 of 3.8 to 26 centistokes (mm ² / s) (ASTM D-445).

The lubricating fluid for use in the internal combustion engine is suitably 2 to 80 centistokes (mm ² / s), preferably 3 to 70 centistokes (mm ² / s), or 4 to 50 centistokes (mm ² / s). ) VK100.

  Natural oils suitable for use as base oils include animal and vegetable oils (eg, castor oil or lard oil), liquid petroleum, and paraffinic, naphthenic, and paraffinic / naphthenic mixed hydrorefining solvent treatments. Or an acid-treated mineral lubricant is included. Oils of lubricating viscosity derived from coal or shale are also useful base oils.

  Alkylene oxide polymers and interpolymers, and their derivatives in which the terminal hydroxyl groups are modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils. Examples of these are polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, alkyl and aryl ethers of these polyoxyalkylene polymers (eg, methyl-polyisopropylene glycol ether having an average molecular weight of 1000, molecular weight of 500 to Diphenyl ether of polyethylene glycol having a molecular weight of 1000, diethyl ether of polypropylene glycol having a molecular weight of 1000 to 1500), and mono- and polycarboxylic acid esters thereof, such as acetic acid ester of tetraethylene glycol, mixed C3-C8 fatty acid ester, and C13 oxo acid Diester.

  Another suitable synthetic lubricant type is a dicarboxylic acid (eg, phthalic acid, succinic acid, alkyl succinic acid, and alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid. Reaction of acid dimer, malonic acid, alkylmalonic acid, alkenylmalonic acid) with various alcohols (eg, butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol) The ester formed by

  Specific examples of these esters include dibutyl adipate, di (2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, phthalic acid Didecyl, dieicosyl sebacate, 2-ethylhexyl diester of linoleic acid dimer, and complex esters formed by the reaction of 1 mole of sebacic acid with 2 moles of tetraethylene glycol and 2-ethylenehexanoic acid.

  Esters useful as synthetic oils include those made from C5 to C12 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol. It is.

  Silicon-based oils, such as polyalkyl-, polyaryl-, polyalkoxy, or polyaryloxysiloxane oils and silicate ester oils, include another useful class of synthetic lubricants that contain silicic acid. Tetraethyl, tetraisopropyl silicate, tetra- (2-ethylhexyl) silicate, tetra- (4-methyl-2-ethyl-hexyl) silicate, tetra- (p-tetrabutylphenyl) silicate, hexa- (4- Methyl-2-pentoxy) disiloxane, poly (methyl) siloxane, and poly (methylphenyl) siloxane are included. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids (eg, tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid), and polymeric tetrahydrofuran.

  Lubricating fluids can typically contain additives known in the art, such as oxidation inhibitors (antioxidants), dispersants, seal fixing or seal compatibility agents, and / or cleaning agents. It is. The lubricating fluid can also include other lubricant additives that perform certain functions not provided by the main component. These additional additives include, but are not limited to, corrosion inhibitors, viscosity index improvers (or modifiers), pour point depressants, zinc dialkyldithiophosphates, antiwear agents, antifoaming agents, And / or friction modifiers. Suitable additives are described in US-A-5320765 and US-B-6528461. Suitable oxidation inhibitors include, for example, copper antioxidants, phenolic compounds, and / or amine compounds. Suitable dispersants include, for example, succinimide. Suitable detergents include, for example, salicylate, phenolate, and sulfonate detergents. Suitable antiwear additives include zinc dithiophosphate.

  Examples of lubricating base oils and additives used in lubricating fluids are also described in WO-A-2007 / 128740, pages 15-23 and WO-A-2004 / 003116.

  In the context of the present invention, “reducing” the accumulation rate of acidic components in a lubricating fluid includes any degree of reduction, including zero (ie, preventing an increase in component concentration). The reduction can be a comparison with the acid component accumulation rate when the fuel composition is used prior to incorporating the Fischer-Tropsch derived fuel component. The reduction is intended to be used in an internal combustion engine (typically diesel) before the addition of a Fischer-Tropsch derived fuel component (e.g., marketed therefor) with otherwise similar fuel compositions. It can be a comparison with the speed measured when operating the same engine.

  The present invention can include, for example, adjusting the impact of the fuel composition on the acid component accumulation rate by a Fischer-Tropsch derived fuel component to achieve a desired goal.

  Similarly, “reducing” the rate of oxidation or nitration in a lubricating fluid includes any degree of reduction, including zero (ie, prevention of the process). The reduction can be a comparison with the oxidation or nitration rate when the fuel composition is used before incorporating the Fischer-Tropsch derived fuel component. The reduction is intended to be used in an internal combustion engine (typically diesel) before the addition of a Fischer-Tropsch derived fuel component (e.g., marketed therefor) with otherwise similar fuel compositions. It can be a comparison with the speed measured when operating the same engine.

  The present invention can include, for example, adjusting the effect of the fuel composition on the lubricating fluid oxidation and / or nitration rate with a Fischer-Tropsch derived fuel component to achieve a desired goal.

  Reduction of the acidic component accumulation rate or oxidation or nitration rate of the lubricating fluid may also include mitigation of at least some increase in the rate due to another cause (ie, a cause other than the nature of the engine fuel).

  Acid component build-up rate, or oxidation or nitration rate, is measured over a predetermined period (ie, engine operating time), specifically over a period starting from the point of introduction of the (previously unused) lubricating fluid into the engine. can do. The speed can be measured, for example, over 100 hours of engine operation time, or 200 hours or more, or 250 hours or more, such as 300 or 400 or 500 hours or more after introduction of the lubricating fluid into the engine.

  Alternatively, the speed can be measured over a predetermined engine working distance, specifically starting from the point at which (previously unused) lubricating fluid is introduced into the engine. This speed can be measured, for example, over 5000 engine miles, or over 8000 engine miles, or over 10,000 engine miles, or over 13000 or 15000 engine miles after introduction of the lubricating fluid into the engine.

  Accordingly, the speed can be expressed as a change per unit engine operating time or as a change per unit engine operating distance.

  The concentration of acidic components in the lubricating fluid should be evaluated by measuring this acid number using, for example, standard test method ASTM D-664 ("Standard Test Method for Acid Values of Petroleum Products by Potentiometric Titration"). Can do. From two or more such measurements, the accumulation rate of the acidic component over a specific period can be calculated.

  The base number of the lubricating fluid, and thus the rate of decrease of the base number, can also provide an indication of acidic component accumulation in the fluid. Base number is determined by standard test method ASTM D-4739 ("Standard test method for determination of base number by potentiometric titration") or ASTM D-2896 ("Standard test method for base number of petroleum products by potentiometric perchloric acid titration"). Can be measured.

  Thus, the present invention can be used to reduce the rate of increase in acid number and / or decrease in base number of a lubricating fluid.

  The degree of oxidation of the lubricating fluid can be measured, for example, using Fourier transform infrared (FTIR) spectroscopy using standard test method ASTM E-2412 ("Standard practice of monitoring condition of lubricant used by trend analysis using FTIR spectroscopy"). Can be measured. Again, the oxidation rate can be calculated from two or more such measurements over a specific period.

  The degree and / or rate of nitration of the lubricating fluid can also be measured by FTIR spectroscopy, for example using ASTM E-2412.

  When the present invention is used to reduce the acidic component accumulation rate of a lubricating fluid, this reduction is the rate observed when the engine is operating with the fuel composition prior to incorporation of a Fischer-Tropsch derived fuel component. By comparison, it can be a reduction of at least 5%, preferably at least 10%, such as at least 15 or 20 or 25 or 30, or even a further 35 or 40%. This reduction is intended to be used in an internal combustion engine (typically diesel) prior to the addition of a Fischer-Tropsch derived fuel component (e.g., marketed therefor) for similar fuel compositions. The comparison can be made with the accumulation rate of acidic components in the same lubricating fluid when the same engine is operated.

  When the present invention is used to reduce the base rate reduction of the lubricating fluid, this reduction is the rate observed when operating the engine with the fuel composition prior to incorporation of the Fischer-Tropsch derived fuel component. And at least 0.5 or 1%, preferably at least 2%, such as at least 3 or 4 or 5% reduction. This reduction is intended to be used in an internal combustion engine (typically diesel) prior to the addition of a Fischer-Tropsch derived fuel component (e.g., marketed therefor) for similar fuel compositions. This can be compared with the base value decrease rate in the same lubricating fluid when the same engine is operated.

  When the present invention is used to reduce the oxidation rate of a lubricating fluid, this reduction is compared to the rate observed when operating the engine with a fuel composition prior to incorporation of a Fischer-Tropsch derived fuel component. And a reduction of at least 5%, preferably at least 10 or 15 or 20%, or optionally at least 25 or even 30%. This reduction is intended to be used in an internal combustion engine (typically diesel) prior to the addition of a Fischer-Tropsch derived fuel component (e.g., marketed therefor) for similar fuel compositions. In comparison with the oxidation rate in the same lubricating fluid when the same engine is operated.

  When the present invention is used to reduce the nitration rate of a lubricating fluid, this reduction is compared to the rate observed when operating the engine with a fuel composition prior to incorporation of a Fischer-Tropsch derived fuel component. And a reduction of at least 5%, preferably at least 10 or 12 or 15%, or optionally at least 17 or 18%. This reduction is intended to be used in an internal combustion engine (typically diesel) prior to the addition of a Fischer-Tropsch derived fuel component (e.g., marketed therefor) for similar fuel compositions. Can be compared to the nitration rate in the same lubricating fluid when the same engine is operated.

  The present invention can further be used to reduce the sulfation rate of a lubricating fluid, in which case the reduction is observed when the engine is operating with a fuel composition prior to incorporation of a Fischer-Tropsch derived fuel component. There may be a reduction of at least 5 or 10%, preferably at least 20 or 30%, or optionally at least 35 or even 40% compared to the achieved rate.

  Fischer-Tropsch derived fuel components can be used in accordance with the present invention to reduce the frequency of lubricating fluid exchanges and / or to increase the interval between lubricating fluid exchanges. As noted above, the replacement of a lubricating fluid is when the properties and / or performance of the fluid has deteriorated to such an extent that it impairs the performance of the engine in which it is used to lubricate and / or prevents satisfactory functioning. Is absolutely necessary. Specifically, Fischer-Tropsch derived fuel components are used to reduce the frequency of lubricating fluid exchange required for changes in the concentration of acidic components in the fluid and / or changes in the degree of oxidation or nitration. be able to.

  If the present invention is used to increase the required lubricating fluid exchange interval, this increase is necessary when operating the engine with a fuel composition prior to incorporation of a Fischer-Tropsch derived fuel component. It can be an increase of at least 10 or 20%, preferably at least 50 or 60 or 70 or 80%, optionally at least 90 or even 100% compared to the interval being made. This increase is intended to be used in an internal combustion engine (typically diesel) prior to the addition of a Fischer-Tropsch derived fuel component (eg, marketed for it) otherwise similar fuel composition This can be compared with the lubricant replacement interval of the same lubricating fluid when the same engine is operated.

  The point in time that a lubricant change is deemed necessary should be assessed in each case using the same criteria and typically includes the kinematic viscosity of the fluid (eg, kinematic viscosity at 100 ° C.). Thus, if it is determined that a fluid needs to be replaced when a parameter reaches a predetermined value (eg, by a user, by a regulatory engine, or by a lubricant or engine manufacturer), the present invention Can be used to increase the interval before this occurs. The parameter can be, for example, the kinematic viscosity of the fluid, the concentration of acidic components contained in the fluid, the degree of oxidation or nitration, and / or the acid or base number. The parameter can be the concentration of impurities such as metals in the fluid.

  The interval between lubricating fluid exchanges can be measured, for example, with respect to engine operating time and / or distance traveled by a vehicle driven by the engine.

  Use of a Fischer-Tropsch derived fuel component in or as a fuel composition may provide other advantages in addition to those provided by the present invention. Fischer-Tropsch derived fuels are generally considered “clean” fuels and tend to produce less engine emissions. Fischer-Tropsch derived fuels also tend to have relatively high cetane numbers and often require low levels of performance enhancing additives for use in diesel engines. In addition, Fischer-Tropsch derived fuels are biodegradable and non-toxic and are therefore relatively friendly actors in environmentally sensitive areas such as nature reserves and natural parks. The present invention can be used to obtain one or more of these benefits in addition to those discussed above with respect to lubricant degradation.

  Accumulation of corrosive acidic components in the lubricating fluid can increase engine wear. Fluid oxidation and nitration raises acid levels and can affect engine wear as well. Engine wear can also be increased by sludge formation and consequent loss of lubricant performance, and sludge formation is also associated with lubricant oxidation. As a result of increased wear, engine component particles, particularly metals such as iron and copper, may accumulate as additional impurities in the lubricating fluid.

  Accordingly, a fifth aspect of the present invention is the use of a Fischer-Tropsch derived fuel component in an internal combustion engine for use in reducing engine wear rate in the engine while operating with this fuel component. provide.

  A sixth aspect is the use of a Fischer-Tropsch derived fuel component in a fuel composition to reduce engine wear rate in an internal combustion engine operating or intended to operate with the fuel composition Provide use for.

  In the fifth and sixth aspects of the present invention, the engine wear can be in particular acid-induced engine wear, which is induced by the presence of acidic components in the lubricating fluid present in the engine, Or worsen. Alternatively or in addition, engine wear can be wear induced or exacerbated by oxidation or nitration of such lubricating fluids and / or by sludge formation in the fluid. Engine wear includes the desorption of particles of metals such as iron and copper, for example, due to friction between moving parts, or friction between moving parts and a lubricating fluid, and these particles then become impurities (typically (E.g. from engine bearings). This can include corrosion of engine components due to the presence of corrosive materials, particularly acids, in the lubricating fluid.

  The degree of engine wear, and thus the rate of engine wear, can be assessed by visual inspection of engine components and / or by measuring the concentration of wear-derived impurities in the lubricating fluid. Such impurities can include metals such as copper, aluminum, chromium, tin, phosphorus, and in particular iron derived from engine components.

  Thus, the present invention can be used to reduce the rate of wear-inducing impurities, particularly iron, in the lubricating fluid.

  Again, the reduction in engine wear, particularly acid-induced engine wear, that can be achieved using the present invention is a comparison with the engine wear rate when using a fuel composition prior to incorporation of a Fischer-Tropsch derived fuel component. be able to. This reduction is intended to be used in an internal combustion engine (typically diesel) prior to the addition of a Fischer-Tropsch derived fuel component (e.g., marketed therefor) for similar fuel compositions. In comparison with the speed measured when the same engine is operated.

  It has been found that the kinematic viscosity of the lubricating fluid can remain relatively stable when the engine is operated with a fuel composition containing a Fischer-Tropsch derived fuel component. Thus, according to the present invention, the Fischer-Tropsch derived fuel component is for any one of the purposes described above with respect to the first to sixth aspects of the present invention and at the same time, for example during a predetermined period of time. It can be used to reduce fluctuations (especially increases) in the kinematic viscosity of the lubricating fluid.

  According to a seventh aspect, the present invention provides an accumulation rate of acidic components of a lubricating fluid present in an engine, in particular for one or more of the purposes described above with respect to the first to sixth aspects of the present invention. There is provided the use of a fuel composition containing a Fischer-Tropsch derived fuel component in an internal combustion engine to reduce and / or reduce the oxidation or nitration rate of such a lubricating fluid. Again, the engine can be a diesel engine.

  An eighth aspect provides a method of operating an internal combustion engine and / or a system (eg, a motor vehicle) driven by such an engine, the method of the first to sixth aspects of the invention. For the purpose of one or more defined in any one, it includes introducing a fuel composition containing a Fischer-Tropsch derived fuel component into the combustion chamber of the engine. The engine is preferably operated with a fuel composition to reduce the accumulation rate of the acidic component of the lubricating fluid present in the engine and / or to reduce the oxidation or nitration rate.

  Here too, the engine can in particular be a diesel engine. This can be direct injection, for example rotary pump, inline pump, unit pump, electronic control unit injector, or common rail, or indirect injection.

  Throughout the description and claims, the terms “comprise” and “contain”, as well as variations of these terms, eg, “comprising” and “comprises”. ")" Means "including but not limited to" and does not exclude other parts, additives, ingredients, integers, or steps.

  Throughout the description and the claims, the singular includes the plural unless the context requires otherwise. In particular, where indefinite articles are used, this description is to be understood as intended as plural and singular unless the context requires another interpretation.

  Preferred features of each aspect of the invention may be as described for any of the other aspects.

  Other features of the present invention will become apparent from the following examples. Generally speaking, the present invention extends to any novel feature or any novel combination of features disclosed herein (including any appended claims and drawings). Accordingly, a feature, integer, characteristic, compound, chemical moiety, or group described in connection with a particular aspect, embodiment, or example of the invention, is not limited to any other described herein unless otherwise contradicted. It is understood that the present invention is applicable to any aspect, embodiment, or example.

  Further, unless otherwise stated, any feature disclosed herein may be replaced with another feature serving the same or similar purpose.

  The following examples illustrate the use of Fischer-Tropsch derived fuel components in a fuel composition according to the present invention, and evaluate their impact on the properties of a lubricating oil in an engine operating with the fuel composition. .

  The diesel drive was operated for a period of time with conventional petroleum-derived diesel fuel F1, followed by Fischer-Tropsch-derived (GTL) diesel fuel F2. After changing from conventional fuel to GTL fuel, samples are taken at weekly intervals from the lubricating oil used in the equipment, and sample characteristics are analyzed to assess the impact of fuel replacement on lubricant degradation did. Prior to refueling, oil samples were analyzed only every 250 hours, along with the oil change.

  The power plant was a Caterpillar ™ 3408C Marine Generator Set (DITA, direct injection, turbocharger and aftercooler). The engine capacity was 18 liters and the output rating was 320 kW.

  The two test fuels had the properties shown in Table 1 below. The conventional (petroleum-derived) fuel F1 was a commercially available fuel obtained from Gulf Oil Nederland BV. GTL fuel F2 was obtained from the Shell Bintulu factory.

  The lubricating oil was a commercially available Caterpillar® product, Cat® DEO ™ 15W-40. According to the manufacturer's specifications, this mineral oil has VK100 (ASTM D-445) 14.2 centistokes, pour point (ASTM D-97) -30 ° C., viscosity index (ASTM D-2270) 141, and It has a total base number (ASTM D-2896) of 11.3 mg KOH / g.

  During the initial stages of the experiment, the oil was changed every 250 hours. However, it has been found that oil can be changed at half this frequency, ie every 500 hours, after operating for a period of time with GTL fuel. This in itself illustrates the potential of the present invention to reduce the rate of degradation of the lubricating fluid and thereby increase the interval between lubricant changes.

The following properties were measured for each oil sample:
a) Kinematic viscosity at 100 ° C. (VK100, using standard test method ASTM D-445)
b) degree of oxidation (according to FTIR spectroscopy)
c) Degree of nitration (by FTIR spectroscopy)
d) Measure iron content, ASTM D-5185 ("Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) to measure additive elements, wear metals and impurities in the lubricating oil used and select selected elements in the base oil. Standard test method for measuring ") is used. E) Copper content (ASTM D-5185).

  Copper and iron are generally considered to be present as a result of engine wear. Thus, a lower content will indicate a reduction in engine wear and thus an improvement in lubricating oil performance. In oil samples, other such “wear elements” including aluminum, chromium, lead, silicon, sodium and tin were similarly analyzed using ICP-AES (ASTM D-5185).

The results of all these analyzes are shown in Tables 2a and 2b. The number at the top of the table is the engine operating time. The oil change is highlighted in bold. VK100 values are given in mm ² / s. Oxidation and nitration values are in units of absorption / cm.

  This data shows that when the power plant is fueled with GTL fuel, the oxidation and nitration rates of the lubricating oil are significantly reduced compared to when operating with petroleum derived fuel F1. At 7030 engine hours, even after 500 hours of oil change, the level of oil oxidation is lower than that observed when oil is changed at 250 hours with F1. After 250 engine hours, the lubricant oxidation level was 29 units from when using petroleum-derived fuel, but only from 21 units when using GTL fuel, and thus GTL fuel has an oxidation level of about 27 units. % Reduction. Similarly, after 250 engine hours, the lubricant nitration level was 38 units from when using petroleum-derived fuel, but only from 31 units when using GTL fuel, a reduction of about 18%. It was.

  The lubricant sulfation level was also found to be significantly reduced when using GTL fuel, and after 250 engine hours, the sulfation level was about 37 units when using petroleum-derived fuel, but GTL fuel. When used, it was only 22 units, showing a reduction of about 40%.

  The iron content of the oil is also significantly reduced when the motor is operated with GTL fuel. At 7030 engine hours, even after 500 hours of oil change, the iron content did not reach the level found when using petroleum-derived fuels. The result is that the oil's iron content tends to reflect engine wear levels, at least partly due to increased oil oxidation levels (and thus acid-induced corrosion). It continues to function well and shows less wear when used with GTL (Fischer-Tropsch derived) fuel, even after prolonged use.

  Similarly, the copper level in the oil does not appear to increase as rapidly when the motor is operating with GTL fuel as it is operating with more conventional fuel. The low copper level indicates that there are no problems with the power system cooling system and bearings. The aluminum level is also low, indicating a low piston wear level.

  The sulfur content of the oil is also significantly reduced when using GTL fuel.

  On the other hand, the kinematic viscosity of the oil remains relatively stable when using GTL fuel, which is consistent with the observed low oxidation and nitration levels, as well as low impurity concentrations. The relatively low and consistent oil viscosity observed when using GTL fuel indicates the possibility of longer oil change intervals, since excessive increases in viscosity are the main motivation for oil changes. Low viscosity may also be associated with improved fuel economy.

  Therefore, based on these measured characteristics, when operating the engine with Fischer-Tropsch derived fuel, lubricating oil is clearly less frequently every 500 hours without excessively compromising this performance or possible level of engine wear. Can be exchanged.

  Two test vehicles equipped with diesel engines were each supplied with conventional petroleum-derived low-sulfur diesel fuel F3 and Fischer-Tropsch-derived light oil F4. At regular intervals, samples were taken from the lubricants used in the two engines and their acid and base numbers were analyzed. The viscosity of the sample as well as the concentration of several wear elements were also measured.

  The test vehicle was a Peugeot ™ 206 1.9 liter IDI passenger car registered in 2001. These engines were light-load diesel engines using indirect injection (IDI) technology, both of which had low mileage at the start of the test (14535 miles for cars operating with petroleum-derived fuel F3, Fischer-Tropsch derived fuel F4 18645 miles for a car that worked on.

  The two test fuels had the properties shown in Table 3 below. The petroleum derived fuel was a commercially available Hungarian diesel fuel (eg Shell). Fischer-Tropsch derived fuels were obtained from Shell (eg Bintulu) and before testing the two additives, Stadis ™ 450 (antistatic additive, eg Innospec, treat rate 2 ppmw) and Paradyne ™ 655 ( A lubricity improver, such as Infineum, treatment rate 200 ppmw) was added.

（芳香族はＩＰ１５６（「石油製品および関連材料−炭化水素種の測定−蛍光指示薬吸着法」）を用いて測定した。）

(Aromatics were measured using IP156 ("Petroleum products and related materials-Determination of hydrocarbon species-Fluorescent indicator adsorption method").)

  The lubricating fluid used in both test engines was Shell Helix ™ Diesel SuperD 15W40 (eg Shell). To avoid batch-to-batch composition variation, the same batch of lubricant was used throughout the test.

  Immediately before the start of the test, both cars were run for 1 week with commercial UK distillate diesel fuel. At the end of this preconditioning period, all fuel was drained from the tank and then each test fuel was refilled into the tank. Distilled diesel fuel present was not washed away from the system.

  Each test car was then run for 18000 miles (slightly longer than a typical oil drain interval) over an 11 month period. Similar roads and conditions were used for both cars. Because the Fischer-Tropsch derived fuel F4 was a “summer grade” diesel with low temperature flow characteristics that were not compatible with vehicle operation at sub-zero ambient temperatures, this test design was designed to reduce the cold operability problem. Allowed cars to enter the garage during the climate. No drivability problems were reported in any car.

  At the start of the test, each car engine was temporarily run for one mile to circulate the lubricant before taking the first sample. Thereafter, lubricant samples were taken at 2000 mile intervals. Whenever possible, samples were taken at similar mileage for the two test cars.

In particular, the following properties were measured on each sample:
a) Kinematic viscosity at 100 ° C. (VK100, using standard test method ASTM D-445)
b) Total acid number (TAN, ASTM D-664), indicating the amount of acid present in the lubricant, expressed in milligrams of potassium hydroxide per gram of lubricant (mg KOH / g)
c) Total base number (TBN, ASTM D-4739)
d) Iron content (using ICP-AES (ASTM D-5185))

  Table 4 shows the results of the vehicle (Car A) operating with distillate diesel fuel, and Table 5 shows the results of the vehicle (Car B) operating with Fischer-Tropsch derived fuel. Note that no adjustments were made to the measured properties to account for oil sample collection and occasional oil replenishment to maintain sump levels. The first column of each table shows the properties of the new lubricant.

  These data demonstrate that the base number of the oil is well maintained (ie, slower base number decrease) in Car B (a car that operates on Fischer-Tropsch derived fuel). This trend was evident at a standard oil discharge interval of 10,000 miles and continued throughout the test. Similarly, the acid number generally remained low for Car B oil. During the test, TAN values increased at a rate of 0.052 mg KOH / g per 1000 miles for Car A, 0.033 mg KOH / g per 1000 miles for Car B, and were reduced by about 38% for GTL fueled cars . During the same period, the TBN value was reduced by about 5% for car A at a rate of 0.094 mg KOH / g per 1000 miles and for car B at a rate of 0.089 mg KOH / g per 1000 miles.

  Thus, it can be seen that during a standard oil drain interval, Fischer-Tropsch derived fuel can provide a reduction in oil degradation, rather this benefit continues far beyond the standard oil drain interval. This in turn provides the possibility of extending the oil discharge interval for engines fueled with Fischer-Tropsch derived fuel.

  The low acid content of Car B's oil is believed to be due, at least in part, to the low oxidation and nitration rate of this oil as demonstrated in Example 1.

  A slower base number decrease and a corresponding slower acid number increase is also expected to reduce engine wear rates due to acid corrosion (eg, due to nitric acid and carboxylic acid). This is consistent with the low iron content and slow iron accumulation rate observed with the lubricant used in Car B, indicating a reduction in wear in this engine.

Claims (9)

  Use of a Fischer-Tropsch derived fuel component in a fuel composition to reduce the accumulation rate of the acidic component of a lubricating fluid present in an internal combustion engine that is or is intended to operate with the fuel composition Use of.   Use of a Fischer-Tropsch derived fuel component in a fuel composition to reduce the oxidation and / or nitration rate of a lubricating fluid present in an internal combustion engine that is or is intended to operate with the fuel composition Use to do.   Use of a Fischer-Tropsch derived fuel component in a fuel composition for reducing acid-induced engine wear rates in an internal combustion engine operating or intended to operate with the fuel composition.   Use of a Fischer-Tropsch derived fuel component in a fuel composition to reduce the frequency of lubricating fluid exchange in an internal combustion engine that is or is intended to operate with the fuel composition.   Use of a fuel composition containing a Fischer-Tropsch derived fuel component in an internal combustion engine for one or more purposes as defined in claims 1 to 4.   6. Use according to any one of claims 1 to 5, wherein the fuel composition is a diesel fuel composition.   The use according to any one of claims 1 to 6, wherein the concentration of the fuel component derived from Fischer-Tropsch in the fuel composition is 10% v / v or more.   Use according to any one of claims 1 to 7, wherein the Fischer-Tropsch derived fuel component is light oil.   A method of operating an internal combustion engine and / or a system driven by the engine, for one or more purposes as defined in any one of claims 1 to 8, for Fischer-Tropsch derived fuel components Introducing a fuel composition containing: into a combustion chamber of an engine.