EP2771439A1

EP2771439A1 - Dye-stable biofuel blend compositions

Info

Publication number: EP2771439A1
Application number: EP12778929.5A
Authority: EP
Inventors: Marc-Andre Poirier
Original assignee: ExxonMobil Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 2011-10-28
Filing date: 2012-10-18
Publication date: 2014-09-03
Anticipated expiration: 2032-10-18
Also published as: US20130104447A1; WO2013062840A1; CA2852248A1; EP2771439B1

Abstract

The disclosure relates to a dye-stable furnace fuel composition comprising: about 10 to 99 parts by volume of a mineral oil component having an effective boiling range from about 160°C to about 380°C; about 1 to 90 parts by volume of a biocomponent fuel component comprising C 1 -C5 alkyl esterified fatty acids from renewable sources; one or more azo dye components present in an amount from about 0.5 mg/kg to about 5 mg/kg, relative to the total fuel composition; and a tert-butyl-functionalized hydroquinone antioxidant component present in an amount of at least about 50 vppm, relative to the fuel composition, wherein the fuel composition exhibits an increased dye stability, relative to a fuel composition having similar mineral oil and biocomponent fuel components and identical azo dye component(s), but having a different or no antioxidant component.

Description

DYE-STABLE BIOFUEL BLEND COMPOSITIONS

FIELD OF THE INVENTION

[0001] This invention relates to dyed fuel compositions having a biocomponent portion with improved dye stability, e.g., due to less unfavorable interactions between antioxidants, dye components, and biocomponents in the fuel compositions.

BACKGROUND OF THE INVENTION

[0002] The use of azo dyes in coloring fuel compositions is known and has been used, for instance, by several countries to establish a basis for differing taxation rates on different types of fuel compositions, based on the existence or absence of such dyes. Fuel compositions containing azo dyes have also been described in various publications, e.g. , including: U.S. Patent Nos. 4,000,985, 4,473,376, 4,871 ,371 , 6,514,917, and 7,615,085; U.K. Patent No. GB 2014179; Chinese Patent Nos. 1912074 and 1590506; French Patent No. 2172002; S.D. Harvey et al. , Dyes and Pigments (2009), 82(3), pp. 307-315; E.M. May et al, Analyst (Cambridge, UK) (1986), 1 1 1(8), pp. 993-5; CP. Leung et al, Analyst (Cambridge, UK) (1985), 1 10(7), pp. 883-4; and P. Ohs et al, Fresenius' Zeitschrift fuer Analytische Chemie (1985), 321 (4), pp. 337-41.

[0003] Furthermore, the use of various antioxidant components in preventing oxidative degradation of fuel compositions is also known, and specifically the use of sterically hindered phenolic antioxidants, such as hindered phenols and hindered hydroquinones, for oxidative stability of fuel compositions is known. A smattering of examples of publications containing such disclosure includes the following: U.S. Patent Application Publication Nos. 2007/01 13467, 2007/0151 143, 2007/0197412,

2007/0248740, 2007/0249846, 2008/0127550, 2009/0107034, 2009/0151235,

2009/0158644, 2010/0088950, 2010/064576, 201 1/0023351 , 201 1/0067294, and 201 1/0154724; U.S. Patent Nos. 7,582, 126, 7,597,725, and 7,964,002; International Publication No. WO 2008/086897, WO 2009/016400, and WO 2009/108851 ; and Chinese Patent Nos. 101082004, 101353599, 101353600, 101538490, and 101812331.

[0004] Still furthermore, the use of renewable/biofuel compositions has become ubiquitous in the patents and the published literature. However, there has been no mention in the prior art of the impact of interaction between ester-containing biofuels and azo dyes causing decolorization, nor even of the impact of selection of an antioxidant that can be involved in reducing the negative interaction between the biofuel and azo dyes. The instant furnace fuel compositions take advantage of the surprising and unexpected synergistic interaction of specific azo dyes, antioxidants, and (optionally) biofuel components, particularly with respect to stability/colorfastness of the dyes.

SUMMARY OF THE INVENTION

[0005] One aspect of the invention relates to dye-stable furnace fuel compositions comprising: a first amount of a mineral oil component having an effective boiling range from about 160°C to about 380°C; a second amount of a biocomponent fuel component comprising C 1 -C5 alkyl esterified acids from one or more of rapeseed oil, canola oil, soybean oil, coconut oil, sunflower oil, palm oil, palm kernel oil, peanut oil, linseed oil, tall oil, corn oil, castor oil, jatropha oil, jojoba oil, olive oil, flaxseed oil, camelina oil, safflower oil, babassu oil, tallow oil, rice bran oil, and yellow grease; one or more azo dye components present in an amount from about 0.5 mg/kg to about 5 mg/kg, relative to the total fuel composition; and a tert-butyl-functionalized hydroquinone antioxidant component present in an amount of at least about 50 vppm, relative to the fuel composition, wherein a volume ratio of the first amount to the second amount is from about 99: 1 to about 1 :9, and wherein the fuel composition exhibits an increased dye stability, relative to a fuel composition having similar mineral oil and biocomponent fuel components and identical azo dye component(s), but having a different or no antioxidant component.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0006] In one aspect, the invention relates to furnace fuel compositions comprising both mineral oil-based and bio-based (renewable) components and having increased dye stability. By "mineral oil" is meant a fossil/mineral/petroleum fuel source, such as crude oil, and not the commercial organic product, such as sold under the CAS number 8020- 83-5, e.g., by Aldrich. Advantageously, the dye-stable furnace fuel compositions can comprise a blend of a mineral oil portion and a biocomponent portion, an azo dye component, and a tert-butyl-functionalized hydroquinone antioxidant component.

Without being bound by theory, it is believed that the source of the increased dye stability can originate in the specific combination and/or relative amount(s) of azo dye, biocomponent fatty acid alkyl ester, and tert-butyl-functionalized hydroquinone antioxidant, which combination yielded surprising and unexpected dye stability results in aging experiments, particularly in comparison to fuel compositions having similar mineral oil and biocomponent fuel component specifications and identical azo dye component(s), but having a different (meaning not a tert-butyl-functionalized

hydroquinone) or no antioxidant component.

[0007] In accordance with a desired application of the inventive composition as a furnace fuel oil, the mineral oil component can advantageously have an effective boiling range from about 160°C to about 380°C, e.g., from about 175°C to about 365°C or from about 190°C to about 350°C. As used herein, the term "effective boiling range" of a composition is defined to mean the boiling temperature range of the middle 90% of the composition, i.e., the boiling range of T5 to T95, where T [number] represents the temperature required to boil about [number] wt% of the composition (under atmospheric pressure), as measured according to ASTM D-86. For instance, a composition has a T10 boiling point of about 200°C if approximately 10% by weight of the composition has boiled at a temperature of about 200°C.

[0008] Additionally or alternately, the mineral oil component can exhibit one or more of the following properties: a kinematic viscosity at about 40°C of at least 1.5 mm²/s, e.g., at least 1.7 mm²/s, at least 1.9 mm²/s, at least 2.0 mm²/s, at least 2.1 mm²/s, at least 2.2 mm²/s, or at least 2.3 mm²/s; a kinematic viscosity at about 40°C of at most 5.0 mm 2 /s, e.g., at most 4.5 mm 2 /s, at most 4.3 mm 2 /s, at most 4.1 mm 2 /s, at most 3.9 mm 2 /s, at most 3.7 mm 2 /s, or at most 3.5 mm 2 /s; a densi·ty at about 15°C of at most 900 kg/cm 3 , e.g., at most 890 kg/cm³, at most 880 kg/cm³, at most 875 kg/cm³, at most 870 kg/cm³, at most 865 kg/cm 3 , at most 860 kg/cm 3 , at most 855 kg/cm 3 , or at most 850 kg/cm 3 ; a density at about 15°C of at least 750 kg/cm³, e.g., at least 780 kg/cm³, at least 800 kg/cm³, at least 810 kg/cm³, at least 820 kg/cm³, at least 830 kg/cm³, or at least 840 kg/cm³; a flash point of at least 35°C, e.g., at least 38°C, at least 40°C, at least 42°C, at least 44°C, at least 46°C, at least 48°C, at least 50°C, at least 52°C, at least 54°C, at least 56°C, at least 58°C, or at least 60°C; a flash point of at most 85°C, e.g., at most 80°C, at most 75°C, at most 70°C, at most 68°C, at most 66°C, at most 64°C, at most 62°C, at most 60°C, at most 58°C, at most 56°C, or at least 54°C; a T50 boiling point from about 200°C to about 300°C, e.g., from about 210°C to about 295°C, from about 220°C to about 290°C, from about 230°C to about 285°C, or from about 240°C to about 280°C; a sulfur content of at most 750 wppm, e.g., at most 600 wppm, at most 500 wppm, at most 450 wppm, at most 400 wppm, at most 350 wppm, at most 300 wppm, at most 250 wppm, at most 200 wppm, at most 150 wppm, at most 100 wppm, at most 50 wppm, at most 30 wppm, at most 20 wppm, at most 15 wppm, at most 10 wppm, or at most 7 wppm; a total aromatics content from about 10 wt% to about 65 wt%, e.g., from about 15 wt% to about 60 wt%, from about 17 wt% to about 55 wt%, from about 19 wt% to about 50 wt%, or from about 20 wt% to about 48 wt%; and a cetane number/index from about 35 to about 55, e.g., from about 38 to about 52 or from about 40 to about 51.

[0009] The bio-based (renewable) fuel component can advantageously comprise a C₁ -C5 alkyl ester of carboxylic/fatty acids from one or more of rapeseed oil, canola oil, soybean oil, coconut oil, sunflower oil, palm oil, palm kernel oil, peanut oil, linseed oil, tall oil, corn oil, castor oil, jatropha oil, jojoba oil, olive oil, flaxseed oil, camelina oil, safflower oil, babassu oil, tallow oil, rice bran oil, and yellow grease. In one preferred embodiment, the bio-based (renewable) fuel component can advantageously comprise a C₁ -C₂ alkyl ester of carboxylic/fatty acids from one or more of rapeseed oil, canola oil, soybean oil, tallow oil, and corn oil. Whether described as "bio-based," "renewable," "biocomponent," or another similar term herein, it should be understood that this non- mineral component is not chemically synthesized by the hand of man. For clarification, regarding fatty acids/esters, this means that the acyl portion of the fatty acid/ester (i.e., the carbonaceous portion of the fatty acid/ester, which constitutes all the carbons in the chain, including the carbon and oxygen atoms from the carbonyl bond, optionally, but not necessarily, including the acid oxygen and, if applicable, hydrogen atoms), whether existing in a free acid, acid salt, (tri-) glyceride, and/or alkyl esterified form, originates from an organism. The organism may be either naturally occurring or genetically modified, naturally and/or by man's intervention, and still be considered "of natural origin", so long as the acyl portion of the fatty acid is produced by and/or through the organism.

[0010] In one embodiment, the biocomponent portion can comprise and/or be a biodiesel. Biodiesel is described officially by the National Biodiesel Board (USA) according to ASTM D 6751 as a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats; European Standard EN 14214 describes the requirements and test methods for FAME biodiesel. Biodiesel is typically produced by a reaction of a vegetable oil or animal fat with a lower alcohol such as methanol or ethanol, optionally in the presence of a catalyst, to yield the desired lower mono-alkyl esters and glycerin, which can be advantageously removed as a by-product. As used herein, the term "lower", only as it refers to alcohols and alkyl esters, should be understood to mean 1 to 5 carbon atoms, for example 1 to 4 carbon atoms or 1 to 2 carbon atoms.

[0011] The selected (natural) oils/fats can be converted to their corresponding mono- esters, e.g., by a transesterification process using a lower alkanol as the esterifying agent. Methanol is normally preferred to make the methyl esters of the fatty acid components (Fatty Acid Methyl Ester - FAME), as it is the cheapest lower alcohol available, although ethanol can be used to produce an ethyl ester (Fatty Acid Ethyl Ester - FAEE) that can still be useful; higher alcohols, e.g., n-propanol, isopropanol, butanols and/or penatnols can additionally or alternately be used. Using increasingly higher carbon number alcohols can often improve the cold flow properties of the resulting alkyl ester, but generally at the cost of an increasingly less efficient and more costly transesterification reaction. Heat, as well as an acid or a base, can be used to catalyze the reaction. The predominant method for commercial-scale biodiesel is the base-catalyzed process, as it is seen as the most economical process for treating virgin vegetable oils, requiring relatively low temperatures and pressures and producing as high as 98+% conversion yield, if the starting oil is relatively low in moisture and free fatty acid content. Biodiesel produced from animal fats and other sources or by other methods may work better with acid catalysis, which can be slower.

[0012] The fatty acids from which preferred esters can be made can be (less preferably) saturated (containing no carbon-carbon double bonds) and/or (more preferably) unsaturated (containing one or more carbon-carbon double bonds) and can have acyl chain lengths (pre-esterification acid-equivalent numbers of carbons) ranging from 8 to 24 carbons, for example, 8 to 22 carbons, 10 to 22 carbons, 12 to 22 carbons, typically predominantly (i.e., more than 50% by weight) 12 to 18 carbons or 14 to 18 carbons. Non-limiting examples of fatty acids can include, but are not limited to, caprylic acid (C8:0), capric acid (C10:0), lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16: l), sapienic acid (C16:2), stearic acid (C18:0), oleic acid (CI 8: 1), linoleic acid (C18:2), linolenic acid (C18:3), arachidic acid (C20:0), eicosenoic acid (C20: l), eicosadienoic acid (C20:2), mead acid (C20:3), arachidonic acid (C20:4), eicosapentanoic acid (C20:5), behenic acid (C22:0) erucic acid (C22: l), lignoceric acid (C24:0), nervonic acid (C24: l), and the like, and obviously combinations thereof. In many commercially important embodiments, the biocomponent portion can advantageously meet ASTM 6751 and/or EN 14214 specification.

[0013] As desired, the biocomponent portion may optionally contain one or more other fuel performance additives, including, but not limited to, cloud point and/or pour point depressants, cetane improvers, biocides, conductivity improvers, corrosion inhibitors, metal deactivators, detergents, and the like, as well as combinations thereof.

[0014] In the dye-stable furnace fuel compositions according to the invention, the fuel blend can advantageously comprise a first amount of the mineral oil component and a second amount of the biocomponent. In certain embodiments, the volume ratio of the first amount to the second amount (and thus of the mineral oil to the biocomponent portions) can be at most about 99: 1 , e.g., at most about 49: 1 , at most about 33: 1 , at most about 19: 1, at most about 9: 1, at most about 4: 1 , at most about 3: 1, at most about 2: 1, or at most about 1 : 1. Additionally or alternately, the volume ratio of the first amount to the second amount (and thus of the mineral oil to the biocomponent portions) can be at least about 1 :9, e.g., at least about 1 :4, at least about 1 :3, at least about 1 :2, at least about 1 : 1, at least about 2: 1, at least about 3: 1, at least about 4: 1 , or at least about 9: 1.

[0015] Typically, in dyed fuel compositions containing one or more azo dye components, the azo dye component(s) can be present in an amount sufficient to impart a discernible (reddish) color, e.g., in an amount from about 0.5 mg/kg to about 5 mg/kg, relative to the total fuel composition. Examples of azo dye components useful in the invention can include, but are not limited to, one or more of Solvent Red 19, Solvent Red 24, Solvent Red 26, Solvent Red 164, and Sudan Red 462.

[0016] In the dye-stable furnace fuel compositions according to the invention, a tert- butyl-functionalized hydroquinone antioxidant component can be present in certain embodiments. Although antioxidants can be helpful in reducing/minimizing/preventing degradation of the fuel composition, some can also substantially interfere with the fastness (stability) of the dye components, particularly of azo (red color) dyes. Thus, the amount and physico-chemical nature of the antioxidant(s) present in the dye-stable furnace fuel compositions according to the invention should advantageously be managed so as to simultaneously impart sufficient fuel degradation (oxidation) protection and sufficiently little negative interaction with the (azo) dye component(s) in order to maintain and/or not substantially degrade the dye color (i.e. , sufficient dye

fastness/stability) in the fuel composition. Therefore, in certain embodiments, the tert- butyl-functionalized hydroquinone antioxidant component can be present in an amount of at least about 50 vppm, e.g., from about 75 vppm to about 1000 vppm, from about 80 vppm to about 750 vppm, or from about 85 vppm to about 500 vppm, relative to the fuel composition. Examples of tert-butyl-functionalized hydroquinone antioxidant components useful in the invention can include, but are not necessarily limited to, 2,5-di- tert-butyl-l ,4-hydroquinone, 2-tert-butyl-l ,4-hydroquinone, and the like, and

combinations thereof. The tert-butyl-functionalized hydroquinone antioxidant component may optionally contain up to 2 wt% of an additive such as citric acid. It should be noted that even other hindered phenolic-type antioxidants, such as 2,6-di-tert- butyl-4-methylphenol (BHT), did not necessarily provide increased dye

stability/colorfastness, in combination with azo dyes and biocomponent portions containing fatty acid alkyl esters (FAAEs).

[0017] As a result of the synergistic combination of the azo dye component(s), the antioxidant component, and optionally but preferably also the biocomponent portion, the fuel composition can preferably exhibit an increased dye stability, relative to a fuel composition having similar mineral oil and biocomponent fuel components and identical azo dye component(s), but having a different or no antioxidant component. The dye stability can be evidenced by the colorfastness (e.g., whether visually, through colorimetric analysis, or via some other known method) of the (reddish) color imparted to the fuel composition by the azo dye component.

[0018] In certain embodiments, the furnace fuel composition exhibiting an increased dye stability can additionally exhibit one or more of the following characteristics: a total insoluble content, after aging for about 14 weeks at about 43°C, of less than 1.0 mg/lOOmL, e.g., less than 0.5 mg/lOOmL; a Rancimat stability of at least 17 hours, e.g., at least 20 hours; and a filter blocking tendency less than 1.5, e.g., less than 1.2.

[0019] Additionally or alternately, the furnace fuel compositions can satisfy ASTM D-396 specifications and/or can exhibit one or more of the following properties: a kinematic viscosity at about 40°C of at least 1.5 mm 2 /s, e.g., at least 1.7 mm 2 /s, at least 1.9 mm²/s, at least 2.0 mm²/s, at least 2.1 mm²/s, at least 2.2 mm²/s, or at least 2.3 mm²/s; a kinematic viscosity at about 40°C of at most 5.0 mm²/s, e.g., at most 4.5 mm²/s, at most

4.3 mm 2 /s, at most 4.1 mm 2 /s, at most 3.9 mm 2 /s, at most 3.7 mm 2 /s, or at most 3.5 mm²/s; a density at about 15°C of at most 900 kg/cm³, e.g., at most 890 kg/cm³, at most 880 kg/cm³, at most 875 kg/cm³, at most 870 kg/cm³, at most 865 kg/cm³, at most 860 kg/cm 3 , at most 855 kg/cm 3 , or at most 850 kg/cm 3 ; a density at about 15°C of at least 750 kg/cm³, e.g., at least 780 kg/cm³, at least 800 kg/cm³, at least 810 kg/cm³, at least 820 kg/cm 3 , at least 830 kg/cm 3 , or at least 840 kg/cm 3 ; a flash point of at least 35°C, e.g., at least 38°C, at least 40°C, at least 42°C, at least 44°C, at least 46°C, at least 48°C, at least 50°C, at least 52°C, at least 54°C, at least 56°C, at least 58°C, or at least 60°C; a flash point of at most 85°C, e.g., at most 80°C, at most 75°C, at most 70°C, at most 68°C, at most 66°C, at most 64°C, at most 62°C, at most 60°C, at most 58°C, at most 56°C, or at least 54°C; a T90 boiling point from about 270°C to about 350°C, e.g., from about 282°C to about 338°C; a T10 boiling point of at most 240°C, e.g., at most 235°C, at most 230°C, or at most 225°C; a final boiling point (FBP) of at most 400°C, e.g., at most 390°C, at most 380°C, or at most 370°C; a sulfur content of at most 750 wppm, e.g., at most 600 wppm, at most 500 wppm, at most 450 wppm, at most 400 wppm, at most 350 wppm, at most 300 wppm, at most 250 wppm, at most 200 wppm, at most 150 wppm, at most 100 wppm, at most 50 wppm, at most 30 wppm, at most 20 wppm, at most 15 wppm, at most 10 wppm, or at most 7 wppm; a combined content of water and sediment of at most 0.1 vol%, e.g., at most 0.05 vol%; a microcarbon residue content of at most 0.1 wt%, e.g., at most 0.05 wt%; and a copper corrosion value, after about 3 hours exposure at about 50°C, according to ASTM D130, of at most 3.

[0020] Additionally or alternately, the present invention can include one or more of the following embodiments.

[0021] Embodiment 1. A dye-stable furnace fuel composition comprising: a first amount of a mineral oil component having an effective boiling range from about 160°C to about 380°C; a second amount of a biocomponent fuel component comprising C₁ -C5 alkyl esterified acids from one or more of rapeseed oil, canola oil, soybean oil, coconut oil, sunflower oil, palm oil, palm kernel oil, peanut oil, linseed oil, tall oil, corn oil, castor oil, jatropha oil, jojoba oil, olive oil, flaxseed oil, camelina oil, safflower oil, babassu oil, tallow oil, rice bran oil, and yellow grease; one or more azo dye components present in an amount from about 0.5 mg/kg to about 5 mg/kg, relative to the total fuel composition; and a tert-butyl-functionalized hydroquinone antioxidant component present in an amount of at least about 50 vppm, relative to the fuel composition, wherein a volume ratio of the first amount to the second amount is from about 99: 1 to about 1 :9, and wherein the fuel composition exhibits an increased dye stability, relative to a fuel composition having similar mineral oil and biocomponent fuel components and identical azo dye component(s), but having a different or no antioxidant component.

[0022] Embodiment 2. The furnace fuel composition of embodiment 1, wherein the mineral oil component has an effective boiling range from about 175°C to about 365°C, e.g. , from about 190°C to about 350°C.

[0023] Embodiment 3. The furnace fuel composition of any one of the previous embodiments, wherein the biocomponent fuel component comprises a C₁ -C₂ alkyl esterified acid from one or more of rapeseed oil, canola oil, soybean oil, tallow oil, and corn oil.

[0024] Embodiment 4. The furnace fuel composition of any one of the previous embodiments, wherein the ratio of the first amount of the mineral oil component to the second amount of the biocomponent fuel component is from about 49: 1 to about 1 :3, e.g., from about 19: 1 to about 1 : 1. [0025] Embodiment 5. The furnace fuel composition of any one of the previous embodiments, wherein the one or more azo dye components comprises one or more of Solvent Red 19, Solvent Red 24, Solvent Red 26, Solvent Red 164, and Sudan Red 462.

[0026] Embodiment 6. The furnace fuel composition of any one of the previous embodiments, wherein the tert-butyl-functionalized hydroquinone antioxidant component comprises 2-tert-butyl-l,4-hydroquinone and/or 2,5-di-tert-butyl-l ,4-hydroquinone.

[0027] Embodiment 7. The furnace fuel composition of any one of the previous embodiments, wherein the tert-butyl-functionalized hydroquinone antioxidant component is present in an amount from about 75 vppm to about 1000 vppm, relative to the fuel composition.

[0028] Embodiment 8. The furnace fuel composition of any one of the previous embodiments, wherein the furnace fuel composition exhibits one or more of the following characteristics: a total insoluble content, after aging for about 14 weeks at about 43°C, of less than 1.0 mg/lOOmL, e.g., less than 0.5 mg/lOOmL; a Rancimat stability of at least 17 hours, e.g., at least 20 hours; and a filter blocking tendency less than 1.5, e.g., less than 1.2.

EXAMPLES

Example 1

[0029] Example 1 compares the properties in Table 1 of a commercially prepared furnace fuel oil (Fuel 1) with an alternative furnace fuel oil composition consisting of a low sulfur diesel fuel (Fuel 2) as base fuels. The furnace fuel oil was dyed red with an azo (in this case, a diazo) dye selected from Solvent Red 19, Solvent Red 24, Solvent Red 26, Solvent Red 164, Sudan Red 462, and combinations thereof, while Fuel 2 did not contain any azo (red) dye. The distillation results show the wider IBP-FBP range for Fuel 1 (~168°C to ~357°C) as compared with Fuel 2 (~173°C to ~305°C), as well as effective boiling range. Table 1

[0030] Density tests can be conducted according to ASTM D-1298 and/or D-4052. Kinetic viscosity measurements can be made according to ASTM D-445. Flash point determinations can be made using ASTM D-93. Aromatics content can be done according to ASTM D-1319. Sulfur content can be determined according to ASTM D- 5453. Copper corrosion testing can be done according to ASTM D-130. Cetane number/index can be determined according to ASTM D-4737. Electrical conductivity can be measured according to ASTM D-2624. Cloud point can be measured using ASTM D-5573.

Example 2

[0031] Example 2 investigates the properties of certain mineral/bio furnace fuel blends, as shown in Table 2. All furnace fuels met the Standard Specification ASTM D- 396 for fuel oils. Table 2

[0032] Suspended sediment testing can be done in accordance with ASTM D-7321. Water and sediment values can be determined using ASTM D-2709. Microcarbon residue values can be attained using ASTM D-4530. Ash content testing can be done in accordance with ASTM D-874. Example 3

[0033] In Example 3, Fuel 4 (undyed) was a blend of -80 vol% uLSD (Fuel 2) and -20 vol% SME, with no 2-tert-butyl-l ,4-hydroquinone composition, and was stored from August 29, 2008 through January 19, 2009 in an outside furnace tank. The ambient air temperatures to which the fuel was exposed was between about 29°C and about -20°C. Similarly, Fuel 3 was a (dyed) blend of -80 vol% Fuel 1 and -20 vol% TME, with -150 mg/kg 2,6-di-tert-butyl-4-methylphenol (BHT) antioxidant composition, and Fuel 5 was a (dyed) blend of -90 vol% Fuel 1 , -5 vol% SME, -5 vol% TME, and -100 vppm of a 2- tert-butyl-l ,4-hydroquinone composition. These Fuels were stored in an outside furnace tank, exposed to similar ambient air temperatures (between about 31°C and about -15°C) from August 14, 2009 through January 27, 2010. The appearance after this storage period of: Fuel 4 was that there was precipitate (deposits) at the bottom of the bottle; Fuel 5 was that the red dye color was substantially not faded with no observable precipitates/deposits; and Fuel 3 was that the red dye color faded significantly to a yellowish color and there was precipitate (deposits) at the bottom of the bottle.

Example 4

[0034] In Example 4, Fuel 5 and aged Fuel 5 were stored for about 14 weeks in an oven at ~43°C. Aged Fuel 5 was Fuel 5 after storage in the outside furnace tank, as described in a previous Example. After that period, Fuel 5 and aged Fuel 5 were tested for the Rancimat stability (prEN 15751), total insolubles (ASTM D4625), and the filter blocking tendency (ASTM D2068). The results presented in Table 3 show excellent Rancimat stability (-24-30 hours), very low total insolubles (-0.1-0.3 mg/lOOmL), and very low (no) filter blocking tendency (-1) for both fuels.

Table 3

[0035] While the present invention has been described and illustrated by reference to particular embodiments, those of ordinary skill in the art will appreciate that the invention lends itself to variations not necessarily illustrated herein. For this reason, then, reference should be made solely to the appended claims for purposes of determining the true scope of the present invention.

Claims

CLAIMS What is claimed is:

1. A dye-stable furnace fuel composition comprising:

a first amount of a mineral oil component having an effective boiling range from about 160°C to about 380°C;

a second amount of a biocomponent fuel component comprising C₁ -C5 alkyl esterified acids from one or more of rapeseed oil, canola oil, soybean oil, coconut oil, sunflower oil, palm oil, palm kernel oil, peanut oil, linseed oil, tall oil, corn oil, castor oil, jatropha oil, jojoba oil, olive oil, flaxseed oil, camelina oil, safflower oil, babassu oil, tallow oil, rice bran oil, and yellow grease;

one or more azo dye components present in an amount from about 0.5 mg/kg to about 5 mg/kg, relative to the total fuel composition; and

a tert-butyl-functionalized hydroquinone antioxidant component present in an amount of at least about 50 vppm, relative to the fuel composition,

wherein a volume ratio of the first amount to the second amount is from about 99: 1 to about 1 :9, and wherein the fuel composition exhibits an increased dye stability, relative to a fuel composition having similar mineral oil and biocomponent fuel components and identical azo dye component(s), but having a different or no antioxidant component.

2. The furnace fuel composition of claim 1 , wherein the mineral oil component has an effective boiling range from about 175°C to about 365°C, e.g., from about 190°C to about 350°C.

3. The furnace fuel composition of claim 1 or claim 2, wherein the biocomponent fuel component comprises a Ci-C₂ alkyl esterified acid from one or more of rapeseed oil, canola oil, soybean oil, tallow oil, and corn oil.

4. The furnace fuel composition of any one of the previous claims, wherein the ratio of the first amount of the mineral oil component to the second amount of the

biocomponent fuel component is from about 49: 1 to about 1 :3, e.g., from about 19: 1 to about 1 : 1.

5. The furnace fuel composition of any one of the previous claims, wherein the one or more azo dye components comprises one or more of Solvent Red 19, Solvent Red 24, Solvent Red 26, Solvent Red 164, and Sudan Red 462.

6. The furnace fuel composition of any one of the previous claims, wherein the tert- butyl- functionalized hydroquinone antioxidant component comprises 2-tert-butyl-l,4- hydroquinone and/or 2,5-di-tert-butyl-l,4-hydroquinone.

7. The furnace fuel composition of any one of the previous claims, wherein the tert- butyl-functionalized hydroquinone antioxidant component is present in an amount from about 75 vppm to about 1000 vppm, relative to the fuel composition.

8. The furnace fuel composition of any one of the previous claims, wherein the furnace fuel composition exhibits one or more of the following characteristics: a total insoluble content, after aging for about 14 weeks at about 43°C, of less than 1.0 mg/lOOmL, e.g., less than 0.5 mg/mL; a Rancimat stability of at least 17 hours, e.g., at least 20 hours; and a filter blocking tendency less than 1.5, e.g., less than 1.2.