Fuel oil composition having improved lubricity and storage stability

Abstract

This invention relates to the use of fatty acid compositions as additives in fuel compositions having good lubricity properties and storage stability, especially for fuel compositions comprising alcohols with optionally water, and notably fuel compositions for compression-ignition internal combustion engines, in addition to associated methods and uses in relation to producing fuel compositions, operating an internal combustion engine, and / or concerning improved lubricity and / or storage stability.

Description

FUEL OIL COMPOSITION HAVING IMPROVED LUBRICITY AND STORAGE STABILITY

[0001] The present invention relates to novel C1- to C3- alcohol-based fuel oil compositions comprising up to 35 vol.% water and a specific fatty acid composition further defined herein and methods of their production. The fuel oil composition may be used in a compression-ignition engine for improving the lubricity and / or storage stability of said fuel oil composition.Background of Invention

[0002] Modern internal combustion engines are high performance systems requiring maximum efficiency, reliability and safety. Materials engineering and mechanical improvements contribute to engine performance, but all engines are dependent in large part on fuel efficiency for performance. The particular fuel chosen depends on the particular performance requirements of the engine under consideration, economic considerations, and current geopolitical realities.

[0003] Alcohol based fuels are popular fuel sources for internal combustion engines. Alcohol based fuels promote energy conservation and environmental protection because they can be produced from self-renewing energy sources and because the burning of such alcohol-based fuels creates less pollution than the burning of hydrocarbon fuels. High performance alcohol-based fuels are often the fuel of choice in high end applications, such as in aircraft engines and racing engines.

[0004] One such high performance alcohol-based fuel is methanol (methyl alcohol, CH3OH), well known for clean (complete) combustion. The more completely a fuel burns, the higher the fuel efficiency and ultimately engine efficiency. Thus, methanol is a very efficient fuel. However, there are several disadvantages associated with the use of C1- to C3- alcohol based fuels, such as methanol based fuels.

[0005] One disadvantage of C1- to C3- alcohol-based fuels and C1- to C3- alcohol / water fuels is a lack of good lubricating characteristics. This lack of lubricity can often cause problems in pumping fuel from the fuel tank to the combustion chamber and / or the injector nozzle.

[0006] Other lubricity additives such as castor oil, glycerides, fatty acid esters, fatty acid methyl ester (FAME) and synthetic esters, are incompatible with C1- to C3- alcohols and their water blends and show poor stability in the fuels at low temperatures. Furthermore, tests show some of the additives in the prior art are not able to lubricate methanol or methanol-water blends to achieve diesel-like lubricity with treat rates under 1000 ppm.

[0007] Furthermore, the additives should be soluble in the fuel oil composition. If the lubricity additive is not soluble in the fuel oil composition, then the engine will not be sufficiently lubricated when using the fuel, resulting in damaged engine parts.

[0008] Furthermore, the combustion of pure C1- to C3- alcohol fuels may be influenced by condensation of water from the environment. They are hygroscopic in nature, meaning they absorb water from the atmosphere over time. If a relatively large proportion of water is added to the fuel, such as 10%, the influence of environmental water ingress is reduced and / or eliminated. Furthermore, methanol-water blends have the potential to reduce NOx emissions since water molecules do not burn in the engine but absorb energy and evaporate. This has a cooling effect on the engine causing operation temperatures to be lower, making NOx emissions lower too. (NOx is only produced at high combustion temperatures in air).

[0009] It would therefore be of great benefit to provide fuels based on C1- to C3- alcohols possibly also comprising water with the required lubricity. In addition, the fuel oil compositions should have high storage stability, especially high storage stability at low temperatures.

[0010] It is therefore an object of the present invention to provide C1- to C3- alcohol fuel oil compositions comprising up to 35 vol.% water having improved lubricity and storage stability.

[0011] The present inventors have surprisingly discovered that a fuel oil composition based on C1- to C3- alcohols and a relatively high water level can be formulated using fatty acid compositions fulfilling specific requirements which offer the required lubricity and protection while retaining good storage stability. The fuel oil composition of the present invention may be formulated with approximately up to 35 vol.% water, resulting in an aqueous fuel whose properties are relatively independent of subsequent condensation of water from the environment. This makes the fuel oil composition more versatile in applications and more desirable.

[0012] The fuel oil composition of the present invention can be used as the fuel for compression-ignition engines. The present inventors have surprisingly discovered that the use of the fatty acid compositions of the present invention results in diesel like performance in C1- to C3- alcohol-water fuel oil compositions with as little as 500 ppm.

[0013] Thus, in a first aspect the invention provides a fuel oil composition comprising:a) 65 to 99.999 vol% of at least one C1- to C3- alcohol, based on the total volume of the fuel oil composition;b) 0 to 35 vol% water, based on the total volume of the fuel oil composition;c) 0.001 to 5 wt.% fatty acid composition, based on the total weight of the fuel oil composition, which comprisesi) at least 30 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition;ii) at least 3 wt.% C18:2fatty acid(s), based on the total weight of the fatty acid composition; andiii) 4 wt.% C18:3or less fatty acid(s), based on the total weight of the fatty acid composition.

[0014] In a second aspect, the invention provides a use of the fuel oil composition of the first aspect of the present invention as the fuel in a compression-ignition engine for improving the lubricity and / or storage stability of said fuel oil composition, wherein the lubricity is measured using a HFRR method according to modified ISO12156 (particularly modified ISO12156-1:2023) as described herein, and the storage stability is visually assessed after storing the fuel oil composition for up to 28 days, as described herein.

[0015] In a third aspect, the invention provides a method of producing a fuel oil composition comprising the steps of combining 65 to 99.999 vol% of at least one C1- to C3- alcohol, preferably methanol and 0 to 35 vol.% water, based on the total volume of the fuel oil composition with 0.001 to 5 wt.%, based on the total weight of the fuel oil composition, of a fatty acid composition as defined with respect to the first aspect of the present invention.

[0016] In a fourth aspect, the invention provides a method of improving the lubricity and / or storage stability of a fuel oil composition comprising 65 to 99.9 vol% of at least one C1- to C3- alcohol, preferably methanol, and 0 to 35 vol.% water, based on the total volume of the fuel oil composition, the method comprising providing 0.001 to 5 wt.%, based on the total weight of the fuel oil composition, of a fatty acid composition as defined with respect to the first aspect of the present invention. The lubricity is measured using a HFRR method according to modified ISO12156 (particularly modified ISO12156-1:2023) as described herein, and the storage stability is visually assessed after storing the fuel oil composition for up to 28 days as described herein.

[0017] Finally, in a fifth aspect, the invention provides a method of operating a compression-ignition engine comprising providing the fuel oil composition according to the first aspect of the present invention as the fuel in the engine thereby to control wear rate in the injection system of the engine.

[0018] Preferred embodiments are also disclosed in the dependent claims. It will be understood that the preferred features of each aspect of the present invention are regarded as preferred features of every other aspect of the present invention. In particular, all features disclosed relate to embodiments i) and ii) of the fatty acid composition of the present invention.

[0019] Also, it will be understood that various additives used, essential as well as optimal and customary, may react under conditions of formulation, storage or use and that the invention also provides the product obtainable or obtained as a result of any such reaction.Fig.1

[0020] is a comparison of the HFRR results of inventive fatty oil composition 3 with FAME for different treat rates and different fuels.

[0021] The features of the invention relating, where appropriate, to each and all aspects of the invention, will now be described in more detail.

[0022] The present inventors have surprisingly found that C1- to C3- alcohol (-water) fuels can be modified by the addition of a fatty acid composition which provides the required lubricity and protection while retaining compatibility with the fuel and showing improved storage stability.

[0023] Fatty acid composition

[0024] The fuel oil composition comprises 0.001 to 5 wt.% fatty acid composition, based on the total weight of the fuel oil composition, which comprisesi) at least 30 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition;ii) at least 3 wt.% C18:2fatty acid(s), based on the total weight of the fatty acid composition; andiii) 4 wt.% C18:3or less fatty acid(s), based on the total weight of the fatty acid composition.

[0025] Thus, the fatty acid composition according to the invention comprises a mixture of different fatty acids. It should be noted that fatty acids are usually understood to be aliphatic saturated and unsaturated carboxylic acids with an almost exclusively unbranched carbon chain. According to the invention, "fatty acids" are also understood to mean acids which are unsaturated. Furthermore, branching or heteroatoms may be present as long as this does not significantly impair the aliphatic character of the acids. The fatty acid composition comprises the fatty acids in their free form and does not comprise significant amounts of fatty acid esters such as triglycerides.

[0026] The fatty acid composition according to the present invention may be based on saturated or unsaturated, branched or unbranched (= linear) C8- to C22fatty acids, as long as the requirements i) to iii) are fulfilled. This means that the fatty acids may have 8 to 22 carbon atoms. The fatty acid composition comprises at least two, and preferably at least three, at least four or at least five different C8- to C22-fatty acids.

[0027] In one embodiment, the fatty acid composition comprises at least 50 wt.%, such as at least 75 wt.%, in particular at least 90 wt.% or at least 95 wt.% C8- to C22fatty acids, in particular mono- or polyunsaturated, branched or unbranched (= linear) C16- to C20fatty acids or mixtures thereof. Preferably, the fatty acid composition comprises 50 to 100 % by weight, such as 75 to 100 % by weight, in particular 90 to 100 % by weight of C16- to C20fatty acids.

[0028] Typical examples of fatty acids that can be present in the fatty acid composition of the present invention are caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, elaidic acid, vaccenic acid, petroselinic acid, linoleic acid, linolenic acid, ricinoleic acid, 12-hydroxystearic acid, arachidic acid, gadoleic acid, gondoic acid, behenic acid, cetoleic acid and erucic acid.

[0029] In a preferred embodiment, the fatty acid composition consists of fatty acids which comprise carbon, hydrogen and oxygen only.

[0030] It is known to experts that commercial fatty acid compositions generally contain mixtures of fatty acids. In addition, the fatty acids can also be present as technical cuts, such as those produced during the pressure splitting or saponification of natural fats and oils, for example palm oil, palm kernel oil, coconut oil, olive oil, soybean oil, sunflower oil, rapeseed oil, tall oil or tallow.

[0031] In a preferred embodiment, the fatty acid composition comprises one or more fatty acid(s) derived from a natural source, preferably from tall oil or palm oil. In a particularly preferred embodiment, the whole fatty acid composition is derived from oil or palm oil.

[0032] In a preferred embodiment, the fatty acid composition comprises tall oil fatty acids. The fatty acid composition may either consist of tall oil fatty acids, or substantially 100% tall oil fatty acids, or may be a mixture of tall oil fatty acids and other fatty acids or derivatives thereof. Preferably such a mixture contains at least 50 wt.%, more preferably at least 70 wt.%, tall oil fatty acids, based on the total weight of the fatty acid composition.

[0033] In a preferred embodiment, the fatty acid composition comprises palm oil fatty acids. The fatty acid composition may either consist of palm oil fatty acids, or substantially 100% palm oil fatty acids, or may be a mixture of palm oil fatty acids and other fatty acids or derivatives thereof. Preferably such a mixture contains at least 50 wt.%, more preferably at least 70 wt.%, palm oil fatty acids, based on the total weight of the fatty acid composition.

[0034] The fatty acid composition may comprise not more than 9 wt.% saturated fatty acids, preferably not more than 8.5 wt.%, based on the total weight of the fatty acid composition. Saturated fatty acids are fatty acids which do not contain a double bond. The content of saturated fatty acids is measured according to ISO12966-1 (2015).

[0035] In a preferred embodiment, the fatty acid composition comprises at least 85 wt.% of one or more C18-fatty acid(s), such as at least 88 wt.% or at least 90 wt.%, based on the total weight of the fatty acid composition.

[0036] In a preferred embodiment, the fatty acid composition comprises more than 90 wt.% or more than 92 wt.% C18+fatty acid(s), based on the total weight of the fatty acid composition. A C18+fatty acid is a fatty acid with 18 or more carbon atoms.

[0037] The fatty acid composition comprises at least 30 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition. In a preferred embodiment, the fatty acid composition comprises at least 32wt-% or 35 wt.% C18:1fatty acid(s). A C18:1fatty acid is a fatty acid with 18 carbon atoms whose carbon chain has a double bond, such as oleic acid. In a preferred embodiment, the fatty acid composition comprises at least 30 wt.% oleic acid. The fatty acid composition may comprise more than one C18:1fatty acid. In this case, the combined amount must be at least 30 wt.% (or at least 32 or 35 wt.%). The C18:1fatty acid content is measured according to ISO12966-1 (2015). The fatty acid composition may comprise 30 to 90 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition, in particular oleic acid. In a preferred embodiment, the fatty acid composition comprises 30 to 85 wt.% C18:1fatty acid(s), such as 35 to 85 wt.%, based on the total weight of the fatty acid composition.

[0038] The fatty acid composition further comprises at least 3 wt.% C18:2fatty acid(s), based on the total weight of the fatty acid composition. In a preferred embodiment, the fatty acid composition comprises at least 5 wt.%, such as at least 7 wt.% or at least 8 wt.% C18:2fatty acid(s). A C18:2fatty acid is a fatty acid with 18 carbon atoms whose carbon chain has two double bonds, in particular linoleic acid. The fatty acid composition may comprise more than one C18:2fatty acid. In this case, the combined amount must be at least 3 wt.% (or at least 5 or 8 wt.%). The C18:2fatty acid content is measured according to ISO12966-1 (2015). The fatty acid composition may comprise 3 to 70 wt.% C18:2fatty acid(s), such as 5 to 60 wt.% C18:2fatty acid(s), based on the total weight of the fatty acid composition, in particular linoleic acid.

[0039] In a preferred embodiment, the fatty acid composition comprises 30 to 90 wt.% C18:1fatty acid(s) and 3 to 70 wt.% C18:2fatty acid(s), both based on the total weight of the fatty acid composition.

[0040] Furthermore, the content of C18:3fatty acids in the fatty acid composition is not more than 4 wt.%, preferably not more than 4 wt.%, such as not more than 3 wt.% or not more than 2 wt.%, based on the total weight of the fatty acid composition. A C18:3fatty acid is a fatty acid with 18 carbon atoms whose carbon chain has three double bonds. The C18:3fatty acid content is measured according to ISO12966-1 (2015). The fatty acid composition may comprise 0 to 4% wt.%, such as 0.05 to 3 wt.% or 0.05 to 2 wt.% C18:3fatty acid, based on the total weight of the fatty acid composition.

[0041] In a preferred embodiment, the content of C22:1fatty acid(s) in the fatty acid composition is from 0.05 to 0.35 wt.% C22:1fatty acid(s),based on the total weight of the fatty acid composition.

[0042] In a preferred embodiment, the fatty acid composition comprisesi) at least 35 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition;ii) at least 5 wt.% C18:2fatty acids(s), such as at least 8 wt.%; based on the total weight of the fatty acid composition; andiii) 3 wt.% or less C18:3fatty acid(s), such as 2 wt.% or less, based on the total weight of the fatty acid composition.

[0043] In a preferred embodiment, the fatty acid composition comprisesi) 30 to 90 wt.% C18:1fatty acid(s), such as 30 to 85 wt.% or 35 to 85 wt.%, based on the total weight of the fatty acid composition;ii) 3 to 70 wt.% C18:2fatty acids(s), such as 5 to 60 wt.%, based on the total weight of the fatty acid composition;iii) 0 to 4 wt.% C18:3fatty acid(s), such as 0.05 to 3 wt.% or 0.05 to 2 wt.%, based on the total weight of the fatty acid composition.

[0044] In a preferred embodiment, the fatty acid composition comprisesi) 30 to 85 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition;ii) 5 to 60 wt C18:2fatty acids(s), based on the total weight of the fatty acid composition; andiii) 0 to 3 wt.% C18:3fatty acid(s), based on the total weight of the fatty acid composition.

[0045] In a preferred embodiment, the fatty acid composition comprisesi) 30 to 85 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition;ii) 5 to 60 wt.% C18:2fatty acids(s), based on the total weight of the fatty acid composition;iii) 0.05 to 3 wt.% C18:3fatty acid(s), based on the total weight of the fatty acid composition, andiv) 0.05 to 1 wt.% C22:1fatty acid(s), based on the total weight of the fatty acid composition.

[0046] In a preferred embodiment, the fatty acid composition comprisesi) 35 to 85 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition;ii) 8 to 60 wt.% C18:2fatty acids(s), based on the total weight of the fatty acid composition; andiii) 0.05 to 2 wt.% C18:3fatty acid(s), based on the total weight of the fatty acid composition.iv) 0.05 to 0.4 wt.% C22:1fatty acid(s), based on the total weight of the fatty acid composition.

[0047] In a preferred embodiment, the total amount of C18:1, C18:2and C18:3unsaturated fatty acids is at least 90 wt.%, such as at least 91 wt.%.

[0048] The Cloud Point of the fatty acid composition may be below 8°C as measured according to ASTM D7689, such as ASTM D7689-21.

[0049] The acid number of the fatty acid composition is preferably from 120 to 180 mg KOH / g, in particular 140 to 170 mg KOH / g, or 145 to 160 mg KOH / g. The acid number is measured according to ASTM D974, such as ASTM D974-22.

[0050] The saponification number of the fatty acid composition is preferably from 190 to 210 mg KOH / g, in particular 193 to 203 mg KOH / g. Saponification is the hydrolysis of fats or oils to form fatty acids and glycerol. The "saponification number" gives an indication of the amount of hydrolyzeable fat in a sample. The saponification number is measured according to ASTM D94 (particularly method A which may be referred to as ASTM D94A), such as ASTM D94-07(2017) (particularly method A which may be referred to as ASTM D94A-07(2017).

[0051] The iodine value of the fatty acid composition is preferably less than 180, in particular 20 to 160 g iodine / 100 g, such as 80 to 160 g iodine / 100 g. The iodine value indicates the degree of unsaturation of the sample. The iodine value is measured using ASTM D5768, such as ASTM D5768-02(2022).

[0052] Fuel oil composition

[0053] The fuel oil composition of the present invention comprisesa) 65 to 99.999 vol% of at least one C1- to C3- alcohol, such as ethanol or methanol, preferably methanol, based on the total volume of the fuel oil composition;b) 0 to 35 vol.% water, based on the total volume of the fuel oil composition,c) 0.001 to 5 wt.% fatty acid composition, andd) optionally one or more co-additives described herein.

[0054] The C1- to C3- alcohol is a saturated aliphatic alcohol having not more than 3 carbon atoms and may be methanol, ethanol, normal propanol (or linear propanol), and isopropanol. In a preferred embodiment, the at least one C1- to C3- alcohol is selected from methanol, ethanol or mixtures thereof, and in particular methanol. The C1- to C3- alcohol for use in the production of the fuel oil composition may come from any source.

[0055] The methanol for use in the production of some preferred embodiments of the fuel oil composition may come from any source. According to some embodiments, the fuel oil composition comprises a crude methanol. The term “crude methanol” encompasses low purity methanol sources, such as methanol sources containing methanol, water and up to 35 vol.% non-water impurities. The methanol content of crude methanol may be 95 vol.% or less. The crude methanol may be used directly in the fuel without further refining. Typical non-water impurities include higher alcohols, aldehydes, ketones. The term “crude methanol” includes waste methanol, coarse methanol and semi-refined methanol. As one example, the methanol may be a manufactured or waste methanol, or a coarse or semi-refined methanol, or an unrefined methanol. The coarse or waste or semi-refined methanol could typically contain mainly methanol, with the balance being water and amounts of higher alcohols, aldehydes, ketones or other carbon, hydrogen and oxygen molecules arising during the normal course of methanol manufacture. Waste methanol may or may not be suitable depending on the degrees and types of contamination. The references in the present specification to amounts of methanol in the fuel composition by volume, refer to the amount of methanol itself in the methanol source. Thus, where the methanol source is a crude methanol containing 90% methanol and other components, and the amount of this crude methanol in the fuel composition is 80 vol.%, then the actual amount of methanol is considered to be 72 vol.% methanol. The water component in the methanol source is taken into account when determining the amount of water in the fuel composition, and the other impurities are treated as additives when assessing the relative amounts of the components in the products, unless otherwise specified. The higher alcohols, aldehydes and ketones which may be present in the crude methanol may function as soluble fuel extender additives.

[0056] According to some embodiments, the fuel oil composition comprises methanol obtained from bio sources such as sugar. The bio source methanol may be obtained from green feedstocks. The bio source methanol may be a bio reactor product from enzymes or bacteria.

[0057] The fuel oil composition may be a stable single phase fuel composition, in other words a homogeneous fuel. The fuel is typically not an emulsion fuel comprising separate organic and aqueous phases emulsified together. The fuel oil composition may therefore be emulsifier free. The accommodation of additive components in the fuel is assisted by the dual solvency properties of both methanol and water, which will enable dissolution of a wider range of materials across the various water:methanol ratios which can be utilized.

[0058] In a preferred embodiment, the fuel oil composition comprises from 65 to 99.999 vol.%, from 66 to 99 vol.%, from 65 to 98 vol.%, from 65 to 97 vol.%, from 65 to 96 vol.%, from 65 to 95 vol.%, from 70 to 99.999 vol.%, from 70 to 99 vol.%, from 70 to 98 vol.%, from 70 to 97 vol.%, from 70 to 96 vol.%, from 70 to 95 vol.%, from 75 to 99.999 vol.%, from 75 to 99 vol.%, from 75 to 98 vol.%, from 75 to 97 vol.%, from 75 to 96 vol.%, from 75 to 95 vol.%, from 80 to 99.999 vol.%, from 80 to 99 vol.%, from 80 to 98 vol.%, from 80 to 97 vol.%, from 80 to 96 vol.%, from 80 to 95 vol.%, from 85 to 99.999 vol.%, from 85 to 99 vol.%, from 85 to 98 vol.%, from 85 to 97 vol.%, from 85 to 96 vol.%, from 85 to 95 vol.%, from 90 to 99.999 vol.%, from 90 to 99 vol.%, from 90 to 98 vol.%, from 90 to 97 vol.%, from 90 to 96 vol.%, from 90 to 95 vol.%, from 95 to 99.999 vol.%, from 95 to 99.5 vol.%, from 95 to 99 vol.%, from 95 to 98 vol.%, from 95 to 97 vol.%, from 95 to 96 vol.%, from 96 to 99.999 vol.%, from 96 to 99.5 vol.%, from 96 to 99 vol.%, from 97 to 99.999 vol.%, from 97 to 99.5 vol.%, from 97 to 99 vol.% of C1- to C3- alcohol(s), such as methanol, based on the volume of the fuel oil composition.

[0059] Any water of a suitable quality can be used as the source of water for the production of the fuel composition. The source of water may be water included as part of un-distilled coarse methanol, or recycled water, or a crude or contaminated water (for example, sea water containing salts) purified by reverse osmosis, purified by activated substances such as activated carbon, or further chemical treatment, deionisation, distillation or evaporative techniques. The water may come from a combination of these sources. The water quality will impact corrosion through the supply chain up to the point of injection into the engine and engine deposition characteristics, and suitable treatment of fuel with anti-corrosion additives or other methods may in these circumstances be required or preferable.

[0060] Considered in terms of the percentage of water in the fuel oil composition by volume, the relative amount of water in the fuel oil composition may be a minimum of at least 0.2 vol.%, at least 0.5 vol.%, at least 1 vol.%, at least 2 vol.%, at least 3 vol.%, at least 4 vol.%, at least 5 vol.%, at least 6 vol.%, at least 7 vol.%, at least 8 vol.%, at least 9 vol.%, at least 10 vol.%, at least 11 vol.%, at least 12 vol.%, at least 13 vol.%, at least 14 vol.%, at least 15 vol.%, at least 16 vol.%, at least 17 vol.%, at least 18 vol.%, or at least 19 vol.%, at least 20 vol.%, at least 22 vol.%, at least 25 vol.%, or at least 30 vol.% water, based on the total volume of the fuel oil composition. The maximum amount of water in the fuel composition may be 34 vol.%, 30 vol.%, 25 vol.%, 23 vol.%, 20 vol.%, 15 vol.%, 10 vol.% or 5 vol.% based on the total volume of the fuel oil composition. Any of the minimum levels may be combined with a maximum level without limitation, save for the requirement that the minimum level be below the maximum water level.

[0061] In one embodiment, the fuel oil composition comprises from 0 to 30 vol.%, preferably from 1 to 26 vol.% or from 5 to 25 vol.% water, based on the total volume of the fuel oil composition.

[0062] In one embodiment, the fuel oil composition comprises from 0.5 to 30 vol.%, from 0.5 to 25 vol.%, from 0.5 to 20 vol.%, from 0.5 to 15 vol.%, from 0.5 to 10 vol.%, or from 0.5 to 5 vol.% water, based on the total volume of the fuel oil composition.

[0063] In a preferred embodiment, the fuel oil composition comprises from 0.002 to 0.2 wt.% fatty acid composition, such as 0.01 to 0.12 wt.%, based on the total weight of the fuel oil composition.

[0064] In a preferred embodiment, the fuel oil composition comprisesa) 70 to 99 vol.% methanol, based on the total volume of the fuel oil composition,b) 1 to 30 vol.% water; based on the total volume of the fuel oil composition, andc) 0.002 to 0.2 wt.% fatty acid composition, based on the total weight of the fuel oil composition.

[0065] In one embodiment, the fuel oil composition may have a chloride content of up to 2 ppm chloride.

[0066] Co-additives

[0067] Co-additives commonly found in fuel oil compositions may optionally be included in the fuel oil composition of the present invention. According to one embodiment, the fuel oil composition comprises at least one co-additive. According to some embodiments, the fuel comprises at least two, three, four, five or six different additives. The amount of co-additives included in the fuel oil composition may take account of the water content of the fuel.

[0068] The co-additives should not cause harmful reactions with the fatty acid composition present in the fuel oil composition of the present invention. Suitable co-additives will be known to those skilled in the art. The co-additives may be added to the fuel either as standard industry traded product (i.e. in a refined form) or as semi processed aqueous solution (i.e. in a non-refined form, semi-refined form, or a crude form). The latter option potentially reduces the cost of the additive.

[0069] In a preferred embodiment, the fuel oil composition of the present invention comprises one or more co-additives selected from the group consisting of anti-pitting additives, ignition improvers, fuel extenders, combustion enhancers, product colouration additives, flame colour additives, anti-corrosion additives, biocides, freeze point depressants, deposit reductants, denaturants, pH controlling agents, and mixtures thereof.

[0070] The above-mentioned co-additives are discussed in further detail as follows; as is known in the art, some additives can provide a multiplicity of effects, for example, a single additive may act as a dispersant and as an oxidation inhibitor.

[0071] Anti-pitting additives

[0072] An anti-pitting additive is an additive that interacts with and reduces the pitting wear on an engine, caused by the rapid condensation of light molecules (cavitation) such as methanol under high pressures in an engine.

[0073] Ignition improvers

[0074] An ignition improver is an additive that promotes the onset of combustion. Molecules of this type are inherently unstable, and this instability leads to “self-start” reaction leading to combustion of the other fuel components (e.g. methanol). The ignition improver may be selected from materials known in the art to have ignition enhancing properties, such as, ethers (including C1- to C6- ethers such as dimethyl ether), alkyl nitrates, alkyl peroxides, volatile hydrocarbons, oxygenated hydrocarbons, and mixtures thereof, in particular dimethyl ether and diethyl ether. Ignition improvers may also be referred to as ignition enhancers. Depending on the type of ignition enhancer chosen, it can be present in amounts of 0.1 – 10 wt.%.

[0075] In addition to the typical ignition improver, finely dispersed carbohydrate particles present in the combustion zone following evaporation of the liquid fuel components prior to ignition may or may not have a role as combustion initiators, however such species present may contribute to more complete and rapid combustion of the total air / fuel mixture.

[0076] Fuel extenders

[0077] A fuel extender is a material that provides heat energy to drive the engine. Materials used as fuel extenders may have this purpose as the main purpose for its inclusion in the fuel composition, or an additive material may provide this function and another function.

[0078] Examples of such fuel extenders are:

[0079] a) Carbohydrates.

[0080] Carbohydrates include sugars and starch. The carbohydrate may be included for fuel extender purposes, although it may also function as an ignition improver, and / or a combustion improver. The carbohydrate is preferably water / methanol soluble, with higher water levels accommodating greater dissolution of sugar in the fuel oil composition. However, as the liquid solvent (water / methanol) in the fuel composition evaporates in the engine, the carbohydrate solute can form micro-fine high surface area suspended particles of low LEL (lower explosive limit) composition which will decompose / react under engine conditions, improving the ignitability of the fuel mixture.

[0081] b) Soluble Fuel Extender additives.

[0082] Fuel extender additives are combustible materials. These additives may be added as separate components or may be part of an undistilled methanol used to produce the fuel oil composition. Such additives include C2to C8-alcohols, ethers, ketones, aldehydes and mixtures thereof.

[0083] Combustion enhancers

[0084] Combustion enhancers may also be referred to as combustion improvers. An example of a combustion enhancer is a nitrated ammonium compound, for example ammonium nitrate. Other nitrated ammonium compounds that can be used include ethylammonium nitrate and triethylammonium nitrate as examples, though these nitrates may also be regarded as ignition enhancers (cetane) rather than combustion enhancers as their main function in the fuel is ignition enhancement. Other combustion improvers can include metallic or ionic species, the latter forming by dissociation under pre or post combustion environments. For example, alkyl nitrates, and metallic / ionic species may be present in treat rates up to 1000 ppm.

[0085] Product colouration additives

[0086] Coloration additives assist to ensure that the fuel composition could not be mistaken for a liquid beverage such as water. Any water-soluble colourant may be used, such as a yellow, red, blue colourant or a combination of these colourants. The colourant may be a standard accepted industry liquid colourant.

[0087] Flame colour additives

[0088] Non-limiting examples of flame colour additives include carbonates or acetates of sodium, lithium, calcium or strontium. The flame colour additives may be selected to achieve the preferred product colour.

[0089] Anti corrosion additives

[0090] Non-limiting examples of anti-corrosion additives include amines and ammonium derivatives.

[0091] Biocides

[0092] While biocides could be added, these are generally not required because the high alcohol (methanol) content in the fuel prevents or inhibits biological growth or biological contamination. Thus, according to some embodiments, the fuel is free of biocides.

[0093] Freeze point depressants

[0094] While freeze point depressants can be incorporated into the fuel oil composition, the methanol (and optional additives such as sugar, added for other purposes) depresses the freezing point of water. Thus, according to some embodiments, the fuel is free of an additional dedicated freeze point depressant.

[0095] Deposit reductants

[0096] Deposit reductants may also be referred to as deposit inhibitors. The deposit reductants may be any suitable commercially available additive. Deposit inhibitors for gasoline, so usually referred to as detergents or dispersants, are well known and a variety of compounds can be used. Examples include polyalkylene amines, and polyalkylene succinimides such as polyisobutenyl succinic anhydride / polyisobutenyl succinic acid.

[0097] PH controlling agents

[0098] An agent that raises or lowers the pH to a suitable pH can be used, which is compatible with the fuel oil composition.

[0099] Method of producing the fuel oil composition

[0100] Further, the present invention relates to a method of producing a fuel oil composition comprising the steps of combining 65 to 99.999 vol% of at least one C1- to C3- alcohol, preferably methanol and 0 to 35 vol.% water, based on the total volume of the fuel oil composition with 0.001 to 5 wt.%, fatty acid composition described above. The fuel oil composition of the present invention can be prepared by mixing C1- to C3- alcohol, such as methanol, the fatty acid composition and water (if present). The mixing can be done by any conventional means known to a person skilled in the art. The mixture may be agitated for a time sufficient to dissolve or disperse the fatty acid composition. Co-additives may be added to the fuel by any method known to those skilled in the art, either before, at the same time as, or after addition of the fatty acid composition. The co-additives may be added directly to the fuel oil composition or by adding them in the form of a concentrate thereof to disperse or dissolve them prior to the addition to the fuel.

[0101] Use of the fuel oil composition

[0102] The present invention further relates to the use of a fuel oil composition as described herein as the fuel in a compression-ignition engine for improving the lubricity and / or storage stability of said fuel oil composition. The lubricity is measured using a high frequency reciprocating rig (HFRR) test according to modified ISO12156 (particularly modified ISO12156-1:2023). The test gives a statement about the lubricity of diesel fuels, which should protect against wear, especially in fuel-lubricated injection pumps. The smaller the wear dome produced in the test, the smaller the HFRR value and the better the lubricity. In a preferred embodiment, the wear is in the fuel pump and / or injector nozzle of the engine.

[0103] In a preferred embodiment, improving the lubricity is assessed in comparison to an otherwise identical fuel oil composition not comprising the fatty acid composition.

[0104] The improvement may include controlling wear rate in the injection system of the engine in operation of the engine. In a preferred embodiment, the wear is in the fuel pump and / or injector nozzle of the engine. The engine may be a 2T CI engine operating at low speeds such as 2000 rpm or less. The engine may also be a Power Generation engine operating at higher loads.

[0105] The storage stability is visually assessed after storing the fuel oil composition for up to 28 days. The fuel oil composition may be stable for at least 1 week, preferably at least 2 weeks or 4 weeks when stored at 10°C or less. The improvement of the lubricity and / or storage stability may be assessed in comparison to an otherwise identical fuel oil composition comprising a fatty acid composition which does not fulfil at least one of the requirements as defined above. Otherwise, improving storage stability may be assessed in comparison to an otherwise identical fuel oil composition comprising other additives known in the art such as castor oil or esters such as FAME, glycerides and synthetic esters.

[0106] In a preferred embodiment, the fuel oil composition is stable for at least 1 week, preferably at least 2 weeks or 4 weeks when stored at 0°C or less, such as -10°C or less.

[0107] Further aspects of the present invention

[0108] Further, the present invention relates to a method of improving the lubricity and / or storage stability of a fuel oil composition comprising 65 to 99.999 vol% of at least one C1- to C3- alcohol, preferably methanol, and 0 to 35 vol.% water, the method comprising providing 0.001 to 5 wt.% of a fatty acid composition as defined above, The lubricity and storage stability is measured as discussed above.

[0109] In addition, the present invention relates to a method of operating a compression-ignition engine comprising providing the fuel oil composition defined herein as the fuel in the engine thereby to control wear rate in the injection system of the engine.

[0110] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Rather, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

[0111] Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention.

[0112] Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0113] While certain particular embodiments of the present invention have been illustrated and described herein, it would be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention, and it is intended, accordingly, to cover in the accompanying claims all such changes and modifications that are within the scope and spirit of this invention.

[0114] Unless otherwise stated or evidently required to be performed under different conditions, measurements described herein are made under standard conditions.

[0115] Measurement Methods used

[0116] Stability Test:

[0117] Fuel oil composition samples containing a certain amount of fatty acid composition were prepared into stability tubes with a tapered bottom. Cork tube stoppers were used to prevent water ingress at low temperatures. The samples were stored at a specified temperature for 28 days. The samples were observed after 24 hours and a visual rating was given. The observations were repeated on Day 7, 14, 21 and 28 of the sample’s storage time.

[0118] Modified HFRR Test for measuring lubricity

[0119] A HFRR Gasoline conversion unit test apparatus was cleaned and prepared in the same manner as ISO12156 (particularly ISO12156-1:2023). The test parameters are given in Table 1.

[0120] ParameterValueFluid volume [ml]15 ± 0.2Stroke length [mm]1 ± 0.02Frequency [Hz]50 ± 1Fluid temperature [°C]25 ± 2Test mass [g]500 ± 1Test duration [min]30 ± 0.1Reservoir surface area [mm2]1470 ± 100

[0121] Analysis of the wear scar on the steel ball bearing was performed either by an operator on a microscope with a micrometre attachment, or with a digital camera. Wear Scars were measured in the same manner as the ISO12156 (particularly ISO12156-1:2023) test method for Diesel fuel lubricity.

[0122] Further details on the measurement methods used is given in the Examples Section below.Examples

[0123] a) Additives tested

[0124] A variety of different fatty acid compositions according to the present invention as well as comparative fatty acid compositions, castor oil and a synthetic ester (mono- and di- glyceride material) were tested for their performance as additives in different fuel oil compositions. An overview over the additives tested is provided in Table 2.

[0125] NumberDescription of tested additive1Fatty acid composition derived from palm oil2Fatty acid composition derived from tall oil3Fatty acid composition derived from tall oil4Fatty acid composition derived from tall oil5Fatty acid composition derived from tall oilComp. 1Fatty acid composition derived from rapeseed oil (High C18:3)Comp. 2Fatty acid composition derived from rapeseed oil (Low C18:3)Comp. 3Fatty acid composition derived from rapeseed oilComp. 4Fatty acid composition derived from tallow oilComp. 5Blend of fatty acids of different originComp. 6Castor OilComp. 7Synthetic Ester

[0126] b) Properties of the different additives tested

[0127] The composition of the fatty acids in the fatty acid compositions / castor oil tested (Inventive Examples 1 to 5 and Comparative Examples 1 to 6) are provided in Table 3.

[0128] The amount of the different fatty acids was measured according to ISO12966-1 (2015). In this test, the bound fatty acids of the triacylglycerols or the free fatty acids are converted into fatty acid methyl esters (FAME), which are determined using capillary gas chromatography. The numbers in Table 3 are weight percentages, based on the total weight of the measured fatty acid composition.

[0129] Fatty Acid12345Comp. 1Comp. 2Comp. 3Comp. 4Comp. 5Comp. 6C8:0C10:00.10.1C12:00.10.2C14:00.10.20.33.3C14:11.3C15:00.3C15 (branched)0.3C15:10.2C16:05.80.40.60.12.66.94.67.552.79.7C16:10.10.60.20.15.70.2C17:00.30.20.10.10.10.10.10.20.10.3C17 (branched)0.8C17:10.20.20.10.20.10.11.30.1C18:01.71.21.42.31.53.41.73.113.410.7C18:181.136.840.459.352.427.864.734.877.729.931.5C18:29.955.850.232.94138.619.148.2140.339C18:30.11.41.40.51.420.86.64.70.522.13.8C20:00.30.20.20.10.20.10.50.30.10.4C20:10.73.454.10.51.11.30.50.80.53.8C20:20.20.20.20.10.10.10.10.2C20:30.1C20:40.1C22:00.30.1C22:10.20.10.20.30.20.10.20.50.40.6C22:60.1C24:00.1C24:1Total100.110010010010010010010010099.9100

[0130] Further properties of the fatty acid compositions were determined using different test procedures identified below. The results are given in Table 4.

[0131] In particular, the Cloud Point of the fatty acid compositions was determined using ASTM D7689, particularly ASTM D7689-21.

[0132] The density at 15°C of the fatty acid compositions was determined using ASTM D4052, particularly ASTM D4052-22.

[0133] If not noted otherwise, the Pour Point of the fatty acid compositions was determined using ASTM D5950, particularly ASTM D5950-14(2020).

[0134] The iodine value of the fatty acid compositions was determined using ASTM D5768, particularly ASTM D5768-02(2022).

[0135] The acid number of the fatty acid compositions was determined using ASTM D974, particularly ASTM D974-22.

[0136] The saponification number of the fatty acid compositions was determined using ASTM D94, particularly ASTM D94A-07(2017). Specifically, the sample was combined with a standardized potassium hydroxide solution, refluxed, and titrated with hydrochloric acid. The endpoint was determined colorimetrically (method A).

[0137] Cloud Point[°C]Density at 15°C [kg / m3]Pour Point [°C]Iodine Value [g iodine / 100 g]Acid No. [mg KOH / g]Sap No.[mg KOH / g]17.36 (D97)95159.091992-12.8-12 (D97)157148.481903-10.3-15151157.411984-4904-8124156.31955-5.5-3135185198Comp. 110.8904-15150136.76199Comp. 26.58906107158.53199Comp. 318135185.13199Comp. 46.4891394156.4198Comp. 5-3.2904-8156211198Comp. 6111101

[0138] Some of the relevant properties of the different additives tested are further summarized in Table 5.

[0139] C18:3 [wt.%]Saturation [wt.%]CP [°C] + 18:3 [wt.%] + Sat [wt.%]C18+[wt.%]C18:1 + C18:2 + C18:3 [wt.%]10.18.1015.59491.121.42.10-9.399.19431.42.40-6.5999240.52.60-0.999.792.751.44.40Comp. 120.810.7042.39487.2Comp. 26.67.6020.794.790.4Comp. 34.711.133.892.287.7Comp. 40.510.101781.379.2Comp. 522.16.3025.296.892.3

[0140] b) Modified HFRR Test

[0141] The different inventive fatty acid compositions 1 to 5 as well as comparative additives 1 to 7 were added to different methanol fuels to obtain methanol fuel oil compositions.

[0142] The lubricating qualities of different methanol fuel oil compositions were examined by the Modified HFRR Test as described above. A comparison to ‘on-spec’ diesel fuel was conducted to indicate an acceptable wear scar value that would give satisfactory performance in the field. This value was determined to be a maximum wear scar limit of 300 µm.

[0143] Fuel compositions containing methanol, water and the fatty acid compositions according to the present invention as well as comparative fatty acid compositions, castor oil and synthetic ester (fatty acid compositions 1 to 5 as well as comparative additives 1 to 7, see Table 2) were tested and compared to this benchmark. Each test was repeated and an average of the wear scar results obtained and reported.

[0144] The tests were conducted on a HFRR Gasoline conversion unit of PCS Instruments, 78 Stanley Gardens, London W3 7SZ, U.K. The test apparatus was cleaned and prepared in the same manner as ISO12156 (particularly ISO12156-1:2023). All testing apparatus in contact with the fuel oil to be tested was cleaned before use. All were submerged in toluene and sonicated for at least 7 minutes, then the hardware was transferred into a container of acetone and sonicated for a further 2 minutes. The hardware was removed and blow dried. They are then immediately assembled on the apparatus for testing. 15 ml (+ / -1ml) of the sample to be tested is poured into a ‘Gasoline’ style reservoir. The Parameters are given in Table 1 above.

[0145] Analysis of the wear scar on the steel ball bearing was performed either by an operator on a microscope with a micrometre attachment, or with a digital camera. Wear scars were measured in the same manner as the ISO12156 (particularly ISO12156-1:2023) test method for Diesel fuel lubricity. The wear scars are elliptical in shape, so to measure its scar size, a measurement is taken in the widest part of one axis (x) then the widest section perpendicular to it (y), and then averaged. Thus, the wear scar corresponds to an average of the linear x and y components of the wear scar region.

[0146] Wear scar (WS) = (x+y) / 2

[0147] The three methanol fuels investigated were pure methanol (IMPCA Grade, >99.85%), M90 (90% methanol, 10% water), and M75 (75% methanol, and 25% water). The additives were added at treat rates ranging from 250 – 1000 ppm. These were then stored at approximately20°C until they were tested on the modified HFRR apparatus, usually within 48 hours.

[0148] The HFRR results for pure methanol and different treat rates of the different additives to be tested (inventive fatty acid compositions 1 to 5) and comparative additives 1 to 7 are given in Table 6. Three measurements were performed and the average was calculated. The data for 250 ppm fatty acid composition 3 in diesel fuel are provided for comparison as well.

[0149] NameTreat Rate [ppm]Measurement 1 [µm]Measurement 2 [µm]Measurement 3 [µm]Avg. Wear Scar [µm]On-Spec Diesel250(example 3)298284291Methanol Base06385355265661250344.5335339.8500195194194.52250341335.5338.3500184201.5192.831504254174354262503633753493625002502102402334150391389444408250394251336327500184187241204Comp. 1150420460425435250349385377370500151179146159Comp. 2150448383425419250289388317331500176180206187Comp. 4150409397413406250214248293252500146208177Comp. 6250435419427.0500429442435.5Comp. 7250439439500408494451

[0150] The HFRR results M90 fuel (Methanol 90%, Water 10%) are given in Table 7. Two measurements for each tested additive were performed and the average was calculated.

[0151] NameTreat Rate [ppm]Measurement 1 [µm]Measurement 2 [µm]Avg. Wear Scar [µm]M900498515506.51250305.5292.5299.0500268.5262265.32250302309.5305.8500259265262.03504354034191502503012762502332632485002472342411000213213Comp. 2250300298299.0500266251258.5Comp. 6250526538532.0500521526523.5

[0152] The HFRR results for M75 fuel (Methanol 75%, Water 25%) are given in Table 8. Again, two measurements for each tested additive were performed and the average was calculated.

[0153] NameTreat Rate [ppm]Measurement 1 [µm]Measurement 2 [µm]Avg. Wear Scar [µm]M750413410411.51250244248.5246.3500237.5249243.32250242.5230236.3500224233228.53503082923001502512742632502272342315002482002241000201201Comp. 2250236250243.0500240.5246.5243.5Comp. 6250428423.5425.8500433430.5431.8

[0154] As can be seen from the data, castor oil (Comparative Example 6) did not significantly improve the lubrication qualities of the fuels. The resulting wear scars were consistently above 400 µm in each case. The synthetic ester also failed to improve the lubricity of pure methanol. Due to its poor stability in water containing methanol fuels, it was not possible to test in these other fuels. All tested fatty acid compositions were able to provide adequate lubricity at modest treat rates (<1000 ppm), in each of the three methanol fuels tested.

[0155] As a comparison, further tests comparing the properties of common additive fatty acid methyl ester (FAME) with the properties of inventive fatty acid composition 3 were tested as well. The results are provided in. The FAME grade used was standard winter FAME from Belgium (Cloud Point -1.2oC, measured according to ASTM D7689, particularly ASTM D7689-21). As can be seen from, much lower treat rates of inventive fatty acid composition 3 are needed to obtain an adequate lubricity compared to FAME.

[0156] Stability Test:

[0157] The additive was measured into a small metal dish and then dropped into a pre-determined fuel sample of desired mass. A lid was added to the container. The sample was then shaken by hand for 10 seconds, and left at room temperature for 16 hours, before being shaken once again for a further 10 seconds. The metal dish was removed. Afterwards, 100 ml of the fuel sample, containing 500 or 1000 ppm fatty acid composition was prepared into a 100 ml graduated stability tube with a tapered bottom. Cork tube stoppers were used to prevent water ingress at low temperatures. This sample was then placed in a fridge / environmental chamber set at the specified temperature (+ / - 2 oC). The sample was observed after 24 hours and a visual rating given. The observations were repeated on Day 7, 14, 21 and 28 of the sample’s storage time.

[0158] In accordance with the procedure outlined above, stability tests were undertaken on various lubricity improver additives, some in the prior art, as well as fatty acid compositions described herein. The fuels tested were IMPCA grade Methanol (99.85%), Methanol with 10% water (tap water, as well as deionised water) referred to as M90 fuel, and finally Methanol with 25% water (tap water as well as deionised water) referred to as M75 fuel. Temperatures for storage were 20oC, 10oC, 0oC, -10oC, -15oC, and -30oC. Treat Rates examined ranged from 500 to 2000 ppm.

[0159] The results are given in Table 9 to 13. In these tables, the following abbreviations are used:CB  Clear & BrightFlocc. Flocculation / SuspensionSed. SedimentationSep Separationcryst Cystals

[0160] Table 9 shows the results of a first study performed in pure methanol and M75 (MeOH + 25% H2O), storing the samples at 0°C and -10°C. In this study, the storage stability of Inventive Example 4 was compared to the storage stability of Comparative Examples 1, 2 and 4. In study 1, Inventive Example 4 showed the best results.

[0161] Table 10 shows the results of a second study performed in pure methanol, M90 (MeOH + 10% H2O) and M75 (MeOH + 25% H2O), storing the samples between 10 and -30°C. In this study, the storage stability of Inventive Examples 1 to 4 was compared to the storage stability of Comparative Examples 1, 2 and 4. Overall, the Inventive Examples 1 to 4 showed the best storage stability over all test conditions.

[0162] Table 11 shows the results of a third study performed in pure methanol, M90 (MeOH + 10% H2O) and M75 (MeOH + 25% H2O), storing the samples between 10 and -30°C. Since the fuels with a higher water content generally show lower stability, the M75 sample was stored at less severe conditions compared to the pure methanol and M90 sample. In this study, the storage stability of Inventive Example 5 was compared to the storage stability of Comparative Examples 3, 5, 6 and a 50: 50 blend by mass of Comparative fatty acid compositions 2 and 4. Overall, Inventive Example 5 showed the best storage stability over all test conditions.

[0163] Table 12 shows the results of a fourth, comparative study performed in pure methanol, M90 (MeOH + 10% H2O) and M75 (MeOH + 25% H2O) with synthetic ester (Comparative Example 7), storing the samples at 20°C, 0°C and -10°C. The synthetic ester showed poor stability in methanol-water fuels.

[0164] Table 13 is comparative study, measuring the stability of 1 to 4% FAME in methanol. This study demonstrated poor stability for the different FAME concentrations tested.

[0165] Study 10 Days7 Days14 DaysFuelAdditiveTempTreat Rate / ppmTreat Rate / ppmTreat Rate / ppm500100020005001000200050010002000Methanol40 °CCBCBCBCBCBCBCBCBCBComp. 1CBCBCBCBCBCBCBCBCBComp. 2CBCBCBCBCBCBCBCBsed.Comp. 4CBCBCBCBCBCBCBCBCBMeOH + 25% H2O4CBCB CBsed. CBcryst. + sed. Comp. 1CBCB CBFlocc. CB3ml sep Comp. 2CBCB CB0.05ml sep CBsed. Comp. 4CBCB CBsed. CBsed. Methanol4-10 °CCBCBCBCBCBCBCBCBCBComp. 1CBCBCBCBCBCBCBCBCBComp. 2CBCBCBCBCBCBCBCBv. small. SepComp. 4CBCBCBCBCBCBCBCBCBMeOH + 25% H2O4CBCB Flocc.0.1 ml sep CB0.1 ml sep Comp. 1CBCB Flocc.0.1 ml sep 2 ml crystFlocc. + sed. Comp. 2CBCB CB0.1 ml sep Flocc.0.1 ml sep Comp. 4CBCB CB0.1 ml sep small cryst.0.1 ml sep Study 121 Days1 MonthFuelAdditiveTempTreat Rate / ppmTreat Rate / ppm5001000200050010002000Methanol40 °CCBCBCBCBCBCBComp. 1CBCBCBCBCBCBComp. 2CBCBsed.CBCBsed.Comp. 4CBCBCBCBCBCBMeOH + 25% H2O4CBcryst. + sed CB1 ml cryst. Comp. 1small cryst3 ml cryst 1 ml cryst.2 ml cryst. Comp. 2CBcloudy sed small cryst.small sep Comp. 4CBsed CBsed. Methanol4-10 °CCBCBCBCBCBCBComp. 1CBCBCBCBCBCBComp. 2CBCBsmall. SepCBCB0.5 ml spComp. 4CBCBCBCBCBCBMeOH + 25% H2O4small cryst0.1 ml sep 2 ml cryst.0.15 ml sep Comp. 12 ml crystFlocc + sed 2 ml cryst.sed + Flocc Comp. 2small cryst0.1 ml sep 1 ml cryst.0.1 ml sep Comp. 4small cryst0.1 ml sep small cryst.0.15 ml sep

[0166] Study 21 Day7 Days14 Days21 Days28 DaysFuelAdditiveTempTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppm50010005001000500100050010005001000Methanol1-15°C CB CB CB CB CB2 CB CB CB CB CB3 CB CB CB CB CB4 CB CB CB CB CBComp. 1 CB CB CB 0.05ml sep 0.05ml sepComp. 2 CB CB CB CB CBComp. 4 CB CB CB CB CB1-30°C CB CB CB CB CB2 CB CB CB CB CB3 CB CB CB CB CB4 CB CB CB CB CBComp. 1 CB CB CB CB CBComp. 2 CB CB CB CB CBComp. 4 CB CB CB CB CBStudy 21 Day7 Days14 Days21 Days28 DaysFuelAdditiveTempTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppm50010005001000500100050010005001000M901-10 °CCB0.05 ml sepCB0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep2CB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep30.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep40.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sepComp. 10.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sepComp. 20.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sepComp. 4CBCBCB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep1-15°CCB0.05 ml sepCB0.05 ml sepCB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep2CB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep30.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep40.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sepComp. 10.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sepComp. 20.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sepComp. 40.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep1-30°C0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep2CB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep30.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep40.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sepComp. 10.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sepComp. 20.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.15 ml sep0.4 ml sep0.15 ml sep0.4 ml sep0.15 ml sep0.4 ml sepComp. 4CB0.05 ml sepCB0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sepStudy 21 Day7 Days14 Days21 Days28 DaysFuelAdditiveTempTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppm50010005001000500100050010005001000M75110°CCBCB0.05 ml sepCB0.05 ml sepCB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep2CBCBCBCBCB0.05 ml sepCB0.05 ml sepCB0.05 ml sep30.05 ml sepCB0.05 ml sepCB0.05 ml sepCB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep4CBCB0.05 ml sepCB0.05 ml sepCB0.05 ml sepCB0.05 ml sepCBComp. 10.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sepComp. 2CB0.05 ml sep0.05 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sepComp. 40.05 ml sepCB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep10°CCB0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep2CBCBCBCB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep30.05 ml sepCB0.05 ml sepCB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep40.05 ml sepCB0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.05 ml sepComp. 10.05 ml sep0.15 ml sep0.1 ml sep0.2 ml sep0.1 ml sep0.25 ml sep0.1 ml sep0.25 ml sep0.1 ml sep0.25 ml sepComp. 20.05 ml sep0.05 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.15 ml sep0.1 ml sep0.15 ml sep0.1 ml sep0.15 ml sepComp. 40.05 ml sep0.1 ml sep0.1 ml sep0.15 ml sep0.1 ml sep0.2 ml sep0.1 ml sep0.2 ml sep0.1 ml sep0.2 ml sep

[0167] Study 31 Day7 Days14 Days21 Days28 DaysFuelAdditiveTempTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppm50010005001000500100050010005001000Methanol5-15°C CB CB CB CB CBComp. 2 / Comp. 4 CB CB CB CB CBComp. 3 CB CB CB CB CBComp. 5 CB CB CB CB CBComp. 6 CB CB CB CB CB5-30°C CB CB CB flocc floccComp. 2 / Comp. 4 CB CB CB CB CBComp. 3 CB CB CB CB CBComp. 5 CB CB CB CB CBComp. 6 CB CB CB CB CBStudy 31 Day7 Days14 Days21 Days28 DaysFuelAdditiveTempTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppm50010005001000500100050010005001000M905-10 °CCBCBCBCBCBCBCBCBCBCBComp. 2 / Comp. 4CBCBCBCBCBCBCBsed.CBsed.Comp. 3CBCBCBCBCBCBCBCBCBCBComp. 5CBCBCBCBCBCBCBCBCBCBComp. 6CBCBCBCBsed.0.5 ml sepsed.0.6 ml sepsed.>1 ml sep5-15°CCBCBCBCBCBCBCBCBCBCBComp. 2 / Comp. 4CBCBCBCBCBCBCBCBCBCBComp. 3CBCBCBCBCBCBCBCBCBCBComp. 5CBCBCBCBCBCBCBCBCBCBComp. 6CB0.25 ml sepCB0.25 ml sep0.1 ml sep0.1 ml sep0.15 ml sep0.1 ml sep0.2 ml sep0.1 ml sep5-30°CCBCBCBCBCBCBCBCBCBCBComp. 2 / Comp. 4CB0.25 ml sep0.25 ml sep0.25 ml sepsed.sedfloccflocc0.1 ml sep0.2 ml sepComp. 3CBCB0.25 ml sep0.25 ml sepflocc0.1 ml sepfloccflocc1 ml sepfloccComp. 5CBCBCB0.25 ml sepCBsedCBfloccCBfloccComp. 60.25 ml sep0.25 ml sep0.5 ml sep0.7 ml sepflocc0.7 ml sep1.5 ml sep0.3 ml sep1 ml sep0.25 ml sepStudy 31 Day7 Days14 Days21 Days28 DaysFuelAdditiveTempTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppm50010005001000500100050010005001000M75510°CCBCBCBCBCBCBCBCBCBCBComp. 2 / Comp. 4CBCBCBCBCBCBCBCBCBCBComp. 3CBCBCBCBCBCBCBCBCBCBComp. 5CBCBCBCBCBCBCBCBCBCBComp. 6CB0.05 ml sep0.05 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep0.1 ml sep50°CCBCBCB0.25 ml sepCB0.25 ml sepCB0.25 ml sepCB0.25 ml sepComp. 2 / Comp. 4CBCBCB0.25 ml sep0.1 ml sep0.25 ml sep0.1 ml sep0.25 ml sep0.1 ml sep0.25 ml sepComp. 3CB0.25 ml sep0.5 ml sep1 ml sep0.5 ml sep1.5 ml sep0.5 ml sep1.1 ml sep0.5 ml sep1 ml sepComp. 5CB0.25 ml sepCB3 ml sepsed.4.5 ml sepsed.5 ml sepsed.5 ml sepComp. 6HazyHazyHazyHazyCBCBsed.sed.sed.sed.

[0168] Study 41 Day7 Days14 Days21 Days28 DaysTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmTreat Rate / ppmFuelAdditiveTemp50010005001000500100050010005001000MethanolComp. 720CBCBCBCBCBCBCBCBCBCB0CBCBCBCBCBCBCBCBCBCB-10CBCBCBCBCBCBCBCBCBCBM90Comp. 720CBsedCBCBCBsedCBsedCBsed0CBsedCBCBsedsedsedsedCBsed-10CBsedCBsedsedsedsedsedsedsedM75Comp. 720CB0.1 ml sep0.05 ml sep0.05 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep00.05 ml sep0.1 ml sepCB0.05 ml sep0.05 ml sep0.1 ml sep0.1 ml sep0.1 ml sepsedsed-100.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.05 ml sep0.1 ml sep0.1 ml sep0.1 ml sepsedsed

[0169] STUDY 5 (FAME + MeOH)Day 0Day 7Day 16Day 21Day 28Temp [°C]0Methanol 1% FAMECBCB0.1 ml sep0.15 ml sep0.15 ml sepMethanol 2% FAMECB0.15 ml sep0.25 ml sep0.25 ml sep0.25 ml sepMethanol 4% FAMECB0.15 ml sep0.5 ml sep0.5 ml sep0.7 ml sepMethanol / Water (95 / 5) 2% FAMECB1 ml sep1 ml sep1 ml sep0.8 ml sepMethanol / Water (95 / 5) 4% FAMECB3 ml sep3 ml sep3 ml sep2.8 ml sep5Methanol 1% FAMECBCBsm. Sedimentsed.sed.Methanol 2% FAMECBcloudy0.1 ml sed0.15 ml sep0.15 ml sepMethanol 4% FAMECB0.5 ml sep0.6 ml sep0.5 ml sep0.6 ml sepMethanol / Water (95 / 5) 2% FAMECBcloudycloudy + 0.1 ml sepcloudy + 0.15 ml sepcloudy + 0.15 ml sepMethanol / Water (95 / 5) 4% FAMECBSed. + Susp.cloudy + 0.6 ml sepCloudy + 0.6 ml sepcloudy + 0.7 ml sep

[0170] From comparing the different stability data sets of the studies conducted provided in Tables 9 to 13, one can draw the following conclusions:

[0171] In pure methanol fuel oil compositions, two comparative fatty acid compositions (Comparative Example 1 and 2) showed sedimentation within 28 days at temperatures of -15°C or above. All other additive compositions were stable in the tests for 28 days.

[0172] In methanol / water fuel (M90, 10% water content), castor oil (Comparative Example 6) consistently showed very bad performance at every temperature, and was the worst performer. The synthetic ester (Comparative Example 7) also showed poor stability in methanol with a water content of 10%. Even though there were some variations, which is not unusual for the type of testing, one can clearly identify trends which demonstrate that overall, the best performing additives for the different storage temperatures in this testing were the fatty acid compositions according to the present invention (Inventive Example 1, 2, 3, 4 5) with Comparative Examples 4 and 5 also showing good results in methanol with a water content of 10% as well.

[0173] In methanol / water fuel M75 (15% water content), castor oil (Comparative Example 6), the synthetic ester (Comparative Example 7) as well as comparative fatty acid compositions 1 to 5 and 50:50 blends of the fatty acid compositions of comparative example 2 and 4 all showed poor performance, particularly at temperatures below 10 °C. Overall, the best performing additives in this fuel were Inventive Examples 1 to 5.

[0174] With this in mind, the fuel oil compositions according to the present invention (Inventive Example 1 to 5) show consistently superior compatibility and stability in methanol and methanol / water fuel blends versus other lubricity additives described in the prior art such as castor oil, synthetic esters or FAME or the other fatty acid compositions not fulfilling the specific requirements defined herein. Thus, the methanolic fuel oil compositions of the present invention can be stored at colder temperatures, for longer periods, without compromising the performance of the fuel and its lubricating properties to protect the engine. Furthermore, a methanol fuel grade with a low water content containing such an additive can be combined with water up to 35%, without concerns over additive compatibility with the fuel composition. This makes the fuel oil compositions of the present invention more versatile in applications and more desirable.

Claims

1. A fuel oil composition comprising:a) 65 to 99.999 vol% of at least one C1- to C3- alcohol, based on the total volume of the fuel oil composition;b) 0 to 35 vol% water, based on the total volume of the fuel oil composition;c) 0.001 to 5 wt.% fatty acid composition, based on the total weight of the fuel oil composition, which comprisesi) at least 30 wt.% C18:1fatty acid(s), based on the total weight of the fatty acid composition;ii) at least 3 wt.% C18:2fatty acid(s), based on the total weight of the fatty acid composition; andiii) 4 wt.% C18:3or less fatty acids, based on the total weight of the fatty acid composition.

2. The fuel oil composition of claim 1, wherein the fatty acid composition comprisesi) at least 35 wt.% C18:1fatty acid(s), and / orii) at least 5 wt.% C18:2fatty acids(s), preferably at least 8 wt.%; and / oriii) 3 wt.% or less C18:3fatty acid(s), preferably 2 wt.% or less.

3. The fuel oil composition of any of the preceding claims, wherein the at least one C1- to C3- alcohol is selected from methanol, ethanol or mixtures thereof, preferably methanol.

4. The fuel oil composition of any of the preceding claims, wherein the composition comprises 70 to 99.999 vol.% C1- to C3- alcohol, preferably from 70 to 99.999 vol.% methanol and / or 0 to 30 vol.%, preferably 1 to 26 vol.% or 5 to 25 vol.% water, based on the total volume of the fuel oil composition.

5. The fuel oil composition of any of the preceding claims which comprises from 0.01 to 0.3 wt.% of said fatty acid composition, preferably 0.02 to 0.15 wt.%, based on the total weight of the fuel oil composition.

6. The fuel oil composition of any of the preceding claims, wherein the fatty acid composition comprises one or more fatty acid(s) derived from a natural source, preferably from tall oil or palm oil, or wherein the whole fatty acid composition is derived from a natural source such as tall oil or palm oil.

7. The fuel oil composition of any of the preceding claims, wherein the fatty acid composition has an iodine value of less than 180 g iodine / 100 g, preferably from 20 to 160 g iodine / 100 g, as measured according to ASTM D5768, preferably ASTM D5768-02(2022), and / or an acid number of between 120 and 180 mg KOH / g, preferably 140 and 170 mg KOH / g, as measured according to ASTM D974, preferably ASTM D974-22.

8. The fuel oil composition of any of the preceding claims, wherein the fuel oil composition is a stable single phase fuel composition.

9. The fuel oil composition of any of the preceding claims, which further comprise one or more additives selected from the group consisting of anti-pitting additives, ignition improvers, fuel extenders, combustion enhancers, oxygen absorbing oil, product colouration additives, flame colour additives, anti corrosion additives, biocides, freeze point depressants, deposit reductants, pH controlling agents, and mixtures thereof.

10. Use of the fuel oil composition of any of the preceding claims as the fuel in a compression-ignition engine for improving the lubricity and / or storage stability of said fuel oil composition, wherein the lubricity is measured using a HFRR method according to modified ISO12156, preferably modified ISO12156-1:2023, as described in the description, and the storage stability is visually assessed after storing the fuel oil composition for up to 28 days, as described in the description.

11. The use of claim 10, wherein storage stability is improved in comparison to an otherwise identical fuel oil composition comprising other additives known in the art such as castor oil or synthetic esters or in comparison to an otherwise identical fuel oil composition comprising a fatty acid composition not fulling the requirements i) or ii) of claim 1.

12. The use of any of claims 10 to 11, wherein improving the lubricity includes controlling wear rate in the injection system of the engine in operation of the engine.

13. The use of any of claims 10 to 12, wherein said fuel oil composition is stable for at least 1 week, preferably at least 2 weeks when stored at below 10°C, preferably below 0°C.

14. Method of producing a fuel oil composition comprising the steps of combining 65 to 99.999 vol% of at least one C1- to C3- alcohol, preferably methanol and 0 to 35 vol.% water, based on the total volume of the fuel oil composition with 0.001 to 5 wt.%, based on the total weight of the fuel oil composition, of a fatty acid composition, as defined in any one of claims 1 to 9.

15. Method of improving the lubricity and / or storage stability of a fuel oil composition comprising 65 to 99.999 vol% of at least one C1- to C3- alcohol, preferably methanol, and 0 to 35 vol.% water, based on the total volume of the fuel oil composition, the method comprising providing 0.001 to 5 wt.%, based on the total weight of the fuel oil composition, of a fatty acid composition as defined in any one of claims 1 to 9, wherein the lubricity is measured using a HFRR method as described in the description, and the storage stability is visually assessed after storing the fuel oil composition for up to 28 days, as described in the description.

16. A method of operating a compression-ignition engine comprising providing the fuel oil composition of any of claims 1 to 9 as the fuel in the engine thereby to control wear rate in the injection system of the engine.

17. The use of claim 12 or method of claim 16, wherein the wear is in the fuel pump and / or injector nozzle of the engine.

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