STABILIZER COMPOSITIONS FOR BLENDS OF PETROLEUM AND RENEWABLE FUELS
Disclosed herein is a fuel oil composition comprising stabilized Renewable Fuel feed stocks or the blends of Petroleum based fuels with such Renewable Fuels. Also described herein are additive compositions for increasing stability of Renewable Fuel feed stocks or the blends of Petroleum based fuels with such Renewable Fuels.
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1. Field of the Invention
This invention relates generally to fuel oil compositions; specifically to stabilization of either Renewable Fuel feed stocks or the blends of Petroleum based fuels with such Renewable Fuels.
2. Description of the Related Art
Renewable Fuels are gaining greater market acceptance as a cutter stock to extend Petroleum Diesel market capacity. The blends of Renewable Fuels with Petroleum Diesel are being used as a fuel for diesel engines, utilized for heating, power generation, and for locomotion with ships, boats, as well as motor vehicles.
The Renewable Cutter stock portion of a blended fuel is commonly known as Bio Diesel. Bio Diesel is defined as fatty acid alkyl esters of vegetable or animal oils. Common oils used in Bio Diesel production are Rapeseed, Soya, Palm Tallow, Sunflower, and used cooking oil or animal fats.
Bio Diesel is prepared by reacting whole oils with alcohols (mainly methanol) in the presence of a catalyst (acid or base), usually sodium hydroxide. This method of preparing Bio Diesel, known as the CD process, is described in numerous patent applications (see, e.g., DE-A 4 209 779, U.S. Pat. No. 5,354,878, EP-A-56 25 04, the entire teachings of which are incorporated herein by reference).
Bio Diesel is a legally registered fuel and fuel additive with the U.S. Environmental Protection Agency (EPA). In order for a material to qualify as a bio diesel, the material/fuel must meet ASTM D6751-03 specifications independent of the oil or fat used or the specific process employed to produce the additive. The ASTM D6751 specification is intended to insure the quality of Bio Diesel to be used as a blend stock for 20% and lower blend levels.
Although Bio Diesel has many positive political and environmental attributes, it also has certain negative characteristics which must be taken into consideration when utilizing the material as an alternative fuel or as a blend stock for Petroleum Diesel. In order for blended fuels to receive greater market acceptance, the end user must have confidence that the fuels will be uniform, stable and will cause no harm to existing equipment.
There are three separate storage and use conditions/parameters which must be considered in order to ensure the uniformity/stability of Bio and Bio blended Petroleum fuels. The end use market requires the Bio feed stock or the Bio/Petroleum fuel mixture to be stable: 1) In storage—where temperatures are low to moderate, 0 to 49° C. (32 to 120° F.), for extended periods of time, 2) In vehicle fuel systems—where temperatures are higher depending on ambient temperature and engine system, 60 to 70° C. (140 to 175° F.), but the fuel is subjected to these higher temperatures for shorter periods of time than in normal storage, and 3) In (or near) the engine—where temperatures reach as high as 150° C. (302° F.) before injection or recycling, but for even shorter periods of time.
The main factors which influence In-storage, In-Vehicle, and In-Engine stability of Bio Diesel and Bio Diesel/Petroleum Diesel fuel blends are Bio Diesel chemical composition, environmental conditions of use and storage, and the composition and characteristics of the Petroleum fuel to which the Bio Diesel is subsequently blended.
It is well known that Bio derived fuels are inherently more oxidatively unstable as compared to petroleum based fuels. The inherent instability is attributed to the abundance of olefinic (unsaturated) materials available in the Bio fuel as compared to Petroleum based fuels. For example; common #2 Diesel contains less than 5% olefins where as bio feeds such as soy are composed of greater than 85% olefins.
The exposure of the Bio Diesel or Bio Diesel/Petroleum Diesel blends to air (oxygen) causes oxidation of the fuel. This process is known as “Oxidative Instability”. The oxidation of the fuel results in the formation of alcohols, aldehydes, ketones, carboxylic acids and further reaction products of these functional groups, some of which may yield polymers.
Bio Diesel is also affected by environmental factors which influence its in-use and in-storage storage stability. These environmental factors include (i) water content, (ii) surface area exposed to the atmosphere, (iii) transparency of the storage container (exposure to sun light), (iv) presence of microorganisms, (v) prior processing of the fuel (Total Acid Value TAV), (vi) exposure to free metals during transport or storage, and (vii) the presence or absence of natural preservatives (such as Tocopherols).
Exposure to water also has detrimental effects on Bio Diesel and Bio Diesel/Petroleum Diesel storage stability. Reaction with water results in the hydrolysis of the ester group affecting an increase in the acid value of the bulk composition.
Water also is an integral component in facilitating biological growth. As microbial organisms produce and utilize enzymes (e.g., lipases) in their normal metabolic pathways, these organisms digest Bio and Petroleum fuels resulting in detrimental changes in the bulk composition (e.g., sludge formation).
Exposure to light greatly enhances the rate and magnitude of oxidation of bio fuels and Bio Diesel Petroleum Diesel blends. The chemical mechanism of light derived hydro peroxide formation is different than free radical peroxide formation. Light enhanced oxidation of Bio fuels or Bio Diesel/Petroleum Diesel blends can not be eliminated by the use of common anti-oxidants.
Presence of free metals in the bulk fuel catalyzes both the formation and decomposition of peroxides. Examples of particularly active oxidation catalysts are copper and manganese, and their complexes. Metals can enter the system through processing, transport, or storage of the Bio Diesel or Bio Diesel/Petroleum Diesel.
Natural preservatives such as Tocopherols (vitamin E derivatives) are present in many natural oils. However, these materials are sometimes removed in processing of the whole oil. This is done intentionally to produce an added value product for resale, or unintentionally due to thermal decomposition or bleaching.
Generally Bio fuels and their blends (in the absence of oxygen and water) are thermally stable. However, prolonged storage at elevated temperatures, causes an increase in rates of other degradation processes (microbial, hydrolytic, and/or oxidation) resulting in enhanced storage instability.
The environmental storage factors and Bio fuel olefin composition greatly affects the instability of the bulk Bio Diesel or Bio Diesel/Petroleum Diesel blends. The degradation products of oxidation such as precipitates and gums can block engine nozzles or generate undesired deposits which can lead to subsequent engine damage. The oxidation of Bio fuels and Bio/Petroleum fuel blends and their subsequent use are of great concern to the fuel producers, engine manufacturers and end fuel users.
The composition of the Petroleum fuel to which Bio Diesel is subsequently blended is also an important factor in fuel instability. There is supporting data which indicates that the propensity of the fuel to form oxidation products is enhanced in blends of Ultra Low Sulfur Diesel (ULSD) and Bio Diesel as compared to each component individually, specifically, the increase in the amount of gums produced upon subjecting the fuel blends to accelerated oxidation (ASTM method D-2274).
One of the methods to enhance or control the stability of fuel is by utilizing stability additives to either treat the base Bio blending stock or to treat the blended Bio/Petroleum fuel.
Although it is commonly accepted that Bio fuels will require stabilization, currently there is a paucity of literature describing the use of additives to stabilize various degradation pathways of Bio fuels or Bio/Petroleum fuel blends.
Recently, there have been applications attempting to address Bio stability, although in a very limited fashion. United States patent application 20040139649, entitled, “Process for increasing the storage stability of bio diesel and the use of 2,4-di-tert-butylhydroxytoluene for increasing the storage stability of bio diesel,” describes the use of 2,4-di-tert-butylhydroxytoluene (BHT) to stabilize bio diesel. This application concentrates on the use of a single antioxidant which functions mainly as a free radical inhibitor. Another recently published United States application 20040123517, “Additives and fuel oil compositions,” describes, in part, the use of hindered phenols as a free radical inhibitor. This application is also limited in scope as the application concentrates solely on BHT.
These applications do not claim, suggest, nor teach the use of any combination of these additives which are required to stabilize the many degradation pathways of Bio fuels or Bio/Petroleum fuel blends.
The present invention addresses the deficiencies of the prior art and is directed in part to the various causes of degradation associated with storage and in-use instability of Bio feed stocks and Bio/Petroleum fuel blends.
BRIEF SUMMARY OF THE INVENTIONThe present invention is directed to a fuel oil composition, specifically to the stabilization of Renewable Fuel feed stocks or the blends of Petroleum based fuels with such Renewable Fuels. Further, the invention is also directed to methods for increasing stabilization of stored fuel oil.
In one embodiment, the invention describes a fuel oil composition for use as, e.g., a fuel in diesel engines. The composition comprises a Renewable component, a Petroleum based component, and a Multifunctional Stabilizer Package.
Another embodiment of the invention is directed toward a method for enhancing the in use and in storage stability of said fuel oil, by adding to the fuel oil either a Bio Diesel blending stock or a Bio Diesel/Petroleum Diesel fuel blend, an additive formulation comprising at least one additives selected from the groups comprising Free Radical Chain Termination Agents, Free Radical Decomposition Agents, Acid Scavengers, Photochemical Stabilizer, Gum Dispersants, and a Metal Sequestering Agents.
In describing the embodiment of the invention, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. The technical equivalence of the additional terms will be readily recognized by a person who is skilled in the art pertaining to this invention.
DETAILED DESCRIPTION OF THE INVENTIONThe present invention is directed to a fuel oil composition; specifically to the stabilized Renewable Fuel feed stocks or the blends of Petroleum based fuels with such Renewable Fuels. The invention is also directed to an additive composition for increasing stability of Renewable Fuel feed stocks or the blends of Petroleum based fuels with such Renewable Fuels.
In one embodiment, the invention describes a fuel oil composition for use as, e.g., a fuel in diesel engines. The composition comprises a Renewable Bio Feedstock Component, a Petroleum Based Component, and a Multifunctional Stabilizer Package.
In the present embodiment, a Renewable Bio Feedstock Component is an organic material that is derived from a natural, replenish able feed stock which can be utilized as source of energy. Suitable examples of a Renewable Component include, but are not limited to, Bio Diesel, Ethanol, and Bio Mass. Other Renewable compounds are well known to those skilled in the art.
In the present embodiment, “Bio Diesel” refers to all mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats.
Bio Diesel is commonly produced by the reaction of whole oils with alcohols in the presence of a suitable catalyst. Whole oils are natural triglycerides derived from plant or animal sources. The reaction of whole oil with an alcohol to produce a fatty acid ester and glycerin is commonly referred to as transesterification. Alternatively, Bio Diesel can be produced by the reaction of a fatty acid with an alcohol to form the fatty acid ester.
The fatty acid segments of triglycerides are typically composed of C10-C24 fatty acids, where the fatty acid composition can be uniform or a mixture of various chain lengths. The Bio Diesel according to the invention may comprise single feed sourced components, or blends of multiple feed stocks derived from vegetable(s), or animal(s) origin. The commonly used single or combination feed stocks include, but are not limited to, coconut, corn, palm, rapeseed, safflower, sunflower, soybean, tall oil, tallow, lard, yellow grease, sardine, menhaden, and used cooking oils and fats.
Suitable alcohols used in either of the esterification processes can be aliphatic or aromatic, saturated or unsaturated, branched or linear, primary, secondary or tertiary, and may possess any hydrocarbon chain having lengths from about C-1 to about C-22. The industry and typical choice being identified as methanol.
Bio Diesel composition is established by specification parameters set forth in ASTM D-6751, the entire teaching of which is incorporated herein by reference. The fatty acid ester must meet and maintain the established specification parameters set forth in ASTM D-6751 the regardless of the whole oil feed source or the process utilized for its production.
The ASTM D-6751 specification outlines the requirements for Bio Diesel (B100) to be considered as a suitable blending stock for hydrocarbon fuels.
In the present embodiment, Petroleum Based Component is a hydrocarbon derived from refining Petroleum or as a product of Fischer-Tropsch processes. These products are commonly referred to as Petroleum Distillate Fuels.
Petroleum Distillate Fuels are described to encompass a range of distillate fuel types. These distillate fuels are used in a variety of applications, including automotive diesel engines and in non on-road applications, under both varying and relatively constant speed and load conditions
Petroleum Distillate Fuel oils can comprise atmospheric or vacuum distillates. The distillate fuel can contain cracked gas oil or a blend of any proportion of straight run or thermally or catalytically cracked distillates. The distillate fuel in many cases can be subjected to further processing such hydrogen-treatment or other processes to improve fuel properties. The material can be described as a gasoline or middle distillate fuel oil.
Gasoline is a low boiling mixture of aliphatic, olefinic, and aromatic hydrocarbons, and optionally alcohols or other oxygenated components. Typically, the mixture boils in the range from about room temperature up to about 225° C.
Middle distillates can be utilized as a fuel for locomotion in motor vehicles, air planes, ships and boats; as burner fuel in home heating and power generation and as fuel in multi purpose stationary diesel engines.
Engine fuel oils and Burner fuel oils generally have flash points greater than 38° C. Middle distillates fuels are higher boiling mixtures of aliphatic, olefinic, and aromatic hydrocarbons and other polar and non-polar compounds having a boiling point up to about 350° C. Middle distillates fuels generally include, but are not limited to, kerosene, jet fuels, and various diesel fuels. Diesel fuels encompass Grades No. 1-Diesel, 2-Diesel, 4-Diesel Grades (light and heavy), Grade 5 (light and heavy), and Grade 6 residual fuels. Middle distillates specifications are described in ASTM D-975, for automotive applications (the entire teaching of which is incorporated herein by reference), and ASTM D-396, for burner applications (the entire teaching of which is incorporated herein by reference).
Middle distillates fuels for aviation are designated by such terms as JP-4, JP-5, JP-7, JP-8, Jet A, Jet A-1. JP-4 and JP-5. The Jet fuels are defined by U.S. military specification MIL-T-5624-N, the entire teaching of which is incorporated herein by reference and JP-8 is defined by U.S. Military Specification MIL-T83133-D the entire teaching of which is incorporated herein by reference. Jet A, Jet A-1 and Jet B are defined by ASTM specification D-1655 and Def. Stan. 91 91 the entire teachings of which are incorporated herein by reference.
The different fuels described (Engine fuels, Burner fuels and Aviation Fuels) each have further to their specification requirements (ASTM D-975, ASTM D-396 and D-1655 respectively), allowable Sulfur content limitations. These limitations are generally on the order of up to 15 ppm of Sulfur for On-Road fuels, up to 500 ppm of Sulfur for Off-Road applications and up to 3000 ppm of Sulfur for Aviation fuels.
The Sulfur content limitations (specifically in D-975 on road fuel) were instituted in order for the fuel to be compatible with modern engine technologies (NOx traps, particulate traps, catalyst systems), and to limit adverse environmental consequences of burning sulfur rich fuels. (Reference World-Wide Fuel Charter, April 2000, Issued by ACEA, Alliance of Automobile Manufacturers, EMA and JAMA, the entire teaching of which is incorporated herein by reference).
In the United States, the Environmental Protection Agency (EPA) regulations require the Sulfur content of on road fuel to meet Ultra Low Sulfur (ULS) specification, specifically less than 15 ppm by mass of Sulfur in the finished fuel. Similar regulations are also in place globally.
Fuel used for off road use (Marine, Power, Home Heating) is currently exempted from the 15 ppm limit, but will be regulated for Sulfur content by 2010.
The Renewable Bio Feedstock Component and the Petroleum Based Component may be subsequently blended to produce a mixed fuel. In the present embodiment, the mixed fuel is defined as “Bio/Petroleum Fuel Blends”. The Bio/Petroleum Fuel Blends are mixtures of Bio Diesel with Petroleum based fuels or fuels derived from Fischer-Tropsch processes. These blends are designated by a Bxx notation, where the xx denotes the Renewable Bio Feedstock Component percent composition of the blend. The blends are sometimes available under the name Bio Diesel, although strictly speaking Bio Diesel customarily designates 100% Bio content (B100).
The blending requirements for Bio fuels in a given end use application can be dictated by Federal and/or State Mandates, or can be market driven due to Federal and/or State Incentives.
The blended fuel composition can contain the Renewable Bio Feedstock Component between about 0.5 % (B.5)-to about 50% (B50) by volume. Generally the current on road application in the market has ranged between about B2 to about B20, although higher blends maybe utilized in the future.
Off-Road use, such as Home Heating oil, Power Generation and Marine are typically less restrictive to the Renewable Bio Feedstock Component content of the blend. The Renewable Bio Feedstock Component use range in these applications can be as high as 99.9% (B99.9).
The Petroleum Based Component content of the blend is generally in the range of about 99.5% to about 50% for On-Road applications. The Petroleum Based Component content in Off-Road applications will vary dependent upon the end use requirements. The range of use of the Petroleum Based Component is typically between about 0.1% to about 95%.
Another aspect of the present invention is the stability of Bio Diesel or Bio/Petroleum Fuel Blends. In the present embodiment, “Stability” means resistance of Bio Diesel or Bio/Petroleum Fuel Blends during In-storage, In-Vehicle, or In-Engine to changes in composition as a result of exposure to environmental and storage factors.
In the present embodiment, Multifunctional Stabilizer Package includes additives selected to increase the stability of Bio Diesel or Bio/Petroleum Fuel Blends.
The changes in composition which are sought to be retarded by the Multifunctional Stabilizer Package are: (i) odor (from volatile degradation products), (ii) increase in Total Acid Values (TAV), (iii) increase in Viscosity, (iv) changes in color, and (v) increase in the propensity for formation of precipitates and/or gums.
The present invention describes a combination of additives (Multifunctional Stabilizer Package) to address the problems associated with fuel instability. Suitable additives utilized in the invention to affect the in-use and in-storage stability of Bio Diesel and Bio/Petroleum Fuel Blends are: (i) Free Radical Chain Termination Agents, (ii) Peroxide Decomposition Agents, (iii) Acid Scavengers, (iv) Photochemical Stabilizers, (v) Gum Dispersants, and (vi) Metal Sequestering Agents.
Each additive type or family in the Multifunctional Stabilizer Package is specifically chosen to counteract or intercede in a specific degradation pathway. Although these additives function in the mode selected, it is recognized that certain additives may also possess dual functions. An example of such dual capability is tertiary amines. These amines may concurrently function as Peroxide Decomposition Agents (PDA) and as an Acid Scavengers (AS).
The first group of chemicals suitable for the formulation is Free Radical Chain Termination Agents (FRCTA). These additives function mainly to retard the rate of propagation of peroxides. A non exclusive list of suitable examples in this family include hindered phenols (2,6-di-tertbutyl phenol, 2,6-di-t-butyl-4-methylphenol (BHT), 2,4-dimethyl-6-t-butylphenol, Octyl Gallate, t-butylhydroquinone (TBHQ), tert-butyl-4-hydroxyanisole (BHA)), phenylenediamines (N,N′-di-sec-butyl-p-phenylenediamine and N-sec-butyl-p-phenylenediamine), and Nitro aromatics (Nitro Benzene, Di-Nitrobenzene, Nitro-Toluene, Nitro-Napthalene, and Di-Nitro-Napthalene and alkyl nitro benzenes and poly aromatics).
The second group of chemicals suitable for the formulation is Peroxide Decomposition Agents (PDA). These additives function mainly to decompose already formed peroxides without generating new radical intermediates capable of reacting with oxygen to propagate new peroxides. A non-exclusive list of functional classes, and examples based on a specific hydrocarbon chain length is described herein. The alkyl group exemplified for each functional class is (C8) octyl, however, other chain lengths in the range of about C4-C30 such as butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, uneicosyl, docosyl, tricosyl, and tetracosyl, and their combinations, are also suitable.
The specific families include: tri-alkyl phosphorous compounds such as trioctyl phosphate; alkyl sulfur compounds such as octanethiol, octane sulfide and octanedisulfide; and tertiary nitrogen compounds such as the dimethyl octyl amine, dioctyl methyl amine, trioctyl amine. The tertiary amines are described by the formula depicted in Scheme 1.
wherein,
- R, R′, R″ can be, alkyl-linear, branched, saturated, unsaturated, C1-30; aromatic; poly alkoxy, or cyclic,
- R,R′ can also contain other hetero atoms such as O, N, S, and P, and their resultant functional groups, and
- R′ and R can be incorporated in a cyclic system containing 3-12 members.
The amine functional class may also include tertiary poly amines. The tertiary poly amines are described by the formula depicted in Scheme 2:
wherein,
- R, R′ can be alkyl-linear or branched; C1-30, aromatic, cyclic, polycyclic, poly alkoxy, or carbonyl;
- R,R′ can also contain other hetero atoms such as O, N, S, and P, and their resultant functional groups;
- R and R′ can be incorporated in a ring system containing 3-12 members;
- X can be 1 -6; and
- Y can be 1 -6.
The carbonyl moiety can bridge the polyamine moiety with other organic functionalities. These functionalities can include: amides, imides, imidazolines, carbamates, ureas, imines, and enamines. The parent amine or poly amine can also be converted to their corresponding alkoxylates. The alkoxylates are products derived from the reaction of 1-100 molar equivalents of an alkoxylating agent with the Nitrogen moiety. The required alkoxylating agents are chosen from the group comprising: ethylene oxide, propylene oxide, butylene oxide and Epichlorohydrin, or their mixtures. The alkoxylates can be produced from a single alkoxylating agent or alternatively from a mixture of agents. The alkoxylate derived from mixtures of alkoxylating agent's can be prepared by stepwise addition of the agents to the amine to form block polymers, or can be added as mixed agents to form random block/alternating alkoxylates. These oxyalkylates can also be further derivatized with organic acids to form esters.
In general, it should be recognized that any compound comprising P, S, or N atom can be utilized to meet the requirements of the invention.
The third group of chemicals suitable for the formulation is Acid Scavengers (AS). These additives function primarily to dispose of any acids formed in the oxidation processes. These scavengers are important to prevent a change in the acidity of the Bio Diesel. An increase in the acidity of the fuel facilitates the degradation of the Bio Diesel by catalyzing unwanted reactions such as hydrolysis of the Bio ester, degradation of any peroxides present to form aldehydes and ketones, and increasing the rate of aldol type chemistries of intermediate aldehydes and ketones. The products of these reactions have been implicated responsible for solids or gum formation in the fuel.
A non exclusive list of examples in this family include: primary, secondary, and tertiary amines, and their derivatives. The amine nitrogen in this family can be attached to a linear, branched, saturated, unsaturated, or a cyclic, hydrocarbon, to aromatic or poly aromatic groups, to hydrogen's, or to a combination of these groups. Each hydrocarbon group attached to the nitrogen atom can comprise about C4-C30 atoms. In the case of saturated alky amines, the groups can be defined as butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, uneicosyl, docosyl, tricosyl, and tetracosyl.
A subclass of suitable amines which can also function as Acid Scavengers are polyamines. Suitable polyamines of the present invention are the polyethylene poly amines such as EDA (ethylene diamine), DETA (diethylene triamine), TETA (triethylene tetra amine) and their higher homologs; their alkyl analogs (as exemplified, but not limited to, N-coco-ethylenediamine, N-oleyl-ethylenediamine, and N-butyl-ethylenediamine), and their analogs based on other industrially available spacers such as propyl and hexyl (as exemplified, but not limited to, dipropylenetriamine, and bis-heaxamethylnetriamine); and their subsequent derivatives such as; ester amines, amido amines, imido amines, imidazolines, carbamates, ureas, imines, and enamines. Scheme 3 depicts a general formula describing Acid Scavengers
wherein,
- R, R′ can be H, alkyl-linear, branched, saturated, unsaturated, C1-30; aromatic, cyclic, poly alkoxy and carbonyl,
- R, R′ can also contain other hetero atoms such as O, N, S, and P, and their resultant functional groups,
- R′ and R′ can be incorporated in a cyclic system containing 3-12 members
- Z can be R or
- X can be 1-6, and
- Y can be 1-6.
The fourth group of chemicals suitable for the formulation is Photochemical Stabilizers (PCS). These additives function primarily to react with Singlet Oxygen generated by interaction of light and oxygen in the presence of sensitizers. Photo-oxidation cannot be inhibited by additives which function as Free Radical Chain Termination Agents such as BHT, BHA and tocopherols.
Photo-oxidation can be interrupted by introducing a molecule which reacts more quickly with singlet oxygen than the bio ester. Non exclusive lists of examples in this family include hindered amine light stabilizers (HALS) such as Piperidines.
The fifth group of chemicals suitable for the formulation is Gum Dispersants (GD). These additives function primarily to disperse polymers or high molecular weight compounds either found in the fuel after refining or are the bi-product of oxidation or thermal breakdown. A non exclusive list of chemistries which are applicable to perform this function include polymers of ethylene and unsaturated esters; vinyl alcohols, vinyl ethers and their ester with organic acids; propylene, ethylene, isobutylene adducts with unsaturated carboxylic acids (such as maleic and fumaric acids) and their amide or imide derivatives; acrylic acids and their amide or esters derivatives; polystyrene's; and polymers made from combinations of these monomers.
The sixth group of chemicals suitable for the formulation is Metal Sequestering Agents (MAS). These additives function primarily to chelate metals which can be present in the Bio Diesel or the Bio/Petroleum fuel blends. A non exclusive list of examples in this family includes EDTA (ethylenediamine tetraacetic acid), Citric Acid, and the industry standards DMD (N,N-disalicylidene-1,2-propane diamine).
The individual component of the Multifunctional Stabilizer Package can be combined in ratios required to effectively stabilize the Bio Diesel or the Bio/Petroleum blends.
Generally the Free Radical Chain Termination Agent can be present in the formulation between about 0.0 to about 100%, the Free Radical Decomposition Agent can be present in the formulation between 0-100%, the Photochemical Stabilizer can be present in the formulation about 0.0 to about 100%, and the Metal Sequestering Agent can be present in the formulation between about 0.0 to about 25% of the total stabilizer composition.
Commonly the package contains between about 25 to about 85% Free radical Chain Termination Agent, between about 15 to about 65% Free radical Decomposition Agent, between about 0.0 to about 10% Photochemical Stabilizer, and between about 1 to about 3% of the Metal Sequestering Agent.
The invention further provides a process of dosing the previously described additives to stabilize Bio and Bio/Petroleum fuel blends. These additives can be added to the B100, and the B100 can be subsequently blended with a petroleum based fuel, or the additive can be directly added to the Bio/Petroleum blended fuel.
The additive package dosing rate is directly related to environmental conditions (such as humidity, temperature of storage, exposure to light), fuel handling, and storage conditions (such as surface area exposed to air, duration of storage, stressing from prior processing, impurities in the system including microbes, metals and water), the specific makeup of the bio feed (fatty acid composition) and the petroleum base fuel (crude slate and processing), and their respective blending ratios.
Generally the effective range in which the additive provides protection for in-use and in-storage stability of Bio and Bio/Petroleum blends is between about 0.005 to about 3% by volume of the B100 or the Bio/Petroleum fuel blends.
Another aspect of the invention is the handling properties of the additive composition/package. The package should not only function to enhance in-use and in-storage stability of the Bio fuel and Bio fuel/Petroleum fuel blends, but should also poses certain properties to enable its use in the fuel market. The additive package should be compatible with fuel system components, it should be handle able (low enough viscosity to be pump able), and fluid at the temperature of use in northern winter climates. Generally, fuel additives are required to be liquid at approximately −40° C.
The selected additive formulation in the present invention distinctly addresses the various aspects of instability in both Bio fuels and Bio/Petroleum fuel blends by significantly inhibiting instability mechanisms (oxidative instability, hydrolytic instability, and thermal instability), and substantially diminishing changes in the fuel (acidity, viscosity, color, odor, and gum formation propensity) thereby dramatically increasing the in-storage and in-use stability of Bio fuels and Bio/Petroleum fuel blends. The Multifunctional Stability Package also addresses all handle ability requirements for an additive to be utilized in the petroleum industry.
It is additionally considered as part of the present invention the combination of the additives comprising the Multifunctional Stability Package described herein, with other suitable additives well known to those skilled in the art that are typically used in fuel oils, such as (a) static dissipaters/electrical-conductivity improver additive, (b) low temperature operability/cold flow additives, (c) corrosion inhibitors, (d) lubricity improvers, (e) cetane improvers, (f) detergents, (g) dyes and markers, (h) anti-icing additives, (i) biocides, and (j) demulsifiers/anti haze additives
Static Dissipaters/Electrical Conductivity additives are used to minimize the risk of electrostatic ignition in hydrocarbons fuels and solvents. It is widely known that electrostatic charges can be frictionally transferred between two dissimilar, nonconductive materials. When this occurs, the electrostatic charge thus created appears at the surfaces of the contacting materials. The magnitude of the generated charge is dependent upon the nature of and, more particularly, the respective conductivity of each material. Electrostatic charging is known to occur when solvents and fuels flow through conduits with high surface area or through “fine” filters. The potential for electrostatic ignition and explosion is probably at its greatest during product handling, transfer and transportation. Thus, the situations which are of greatest interest to the petroleum industry are conditions where charge is built up in or around flammable liquids, and the possibility of discharge leading to incendiary sparking, and perhaps to a serious fire or explosion. Countermeasures designed to prevent accumulation of electrostatic charges on a container being filled such as container grounding (i.e., “earthing”) and bonding are routinely employed. However, it has been recognized that grounding and bonding alone are insufficient to prevent electrostatic build-up in low conductivity, volatile organic liquids. Organic liquids such as distillate fuels like diesel, gasoline, jet fuel, turbine fuels and kerosene, and relatively contaminant free light hydrocarbon oils such as organic solvents and cleaning fluids are inherently poor conductors. Static charge accumulates in these fluids because electric charge moves very slowly through these liquids and can take a considerable time to reach a surface which is grounded. Until the charge is dissipated, a high surface-voltage potential can be achieved which can create an incendiary spark, resulting in an ignition or an explosion. The increased hazard presented by low conductivity organic liquids can be addressed by the use of additives to increase the conductivity of the respective fluids. The increased conductivity of the liquid will substantially reduce the time necessary for any charges that exist in the liquid to be conducted away by the grounded inside surface of the container.
Low temperature operability/coldflow additives are used in fuels to enable users and operators to handle the fuel at temperatures below which the fuel would normally cause operational problems. Distillate fuels such as diesel fuels tend to exhibit reduced flow at low temperatures due in part to formation of waxy solids in the fuel. The reduced flow of the distillate fuel affects transport and use of the distillate fuels in refinery operations and internal combustion engine. This is a particular problem during the winter months and especially in northern regions where the distillates are frequently exposed to temperatures at which solid formation begins to occur in the fuel, generally known as the cloud point (ASTM D 2500, the entire teachings of which are incorporated herein by reference) or wax appearance point (ASTM D 3117, the entire teachings of which are incorporated herein by reference). The formation of waxy solids in the fuel will in time essentially prevent the ability of the fuel to flow, thus plugging transport lines such as refinery piping and engine fuel supply lines. Under low temperature conditions during consumption of the distillate fuel, as in a diesel engine, wax precipitation and gelation can cause the engine fuel filters to plug resulting in engine inoperability.
Lubricity improver's increase the lubricity of the fuel, which impacts the ability of the fuel to prevent wear on contacting metal surfaces in the engine. A potential detrimental result of poor lubricating ability of the fuel can be premature failure of engine components (for example, fuel injection pumps).
Corrosion Inhibitors are a group of additives which are utilized to prevent or retard the detrimental interaction of fuel and materials present in the fuel with engine components. The additives used to impart corrosion inhibition to fuels generally also function as lubricity improvers. These additives coat the surfaces of mowing metal parts to inhibit interaction of the metals with water. This coating also functions as a lubricating barrier between the mowing metal parts and results in diminished wear.
Cetane Improvers are used to improve the combustion properties of middle distillates. As discussed in U.S. Pat. No. 5,482,518, the entire teachings of which are incorporated herein by reference, fuel ignition in diesel engines is achieved through the heat generated by air compression, as a piston in the cylinder moves to reduce the cylinder volume during the compression stroke. In the engine, the air is first compressed, then the fuel is injected into the cylinder. As the fuel contacts the heated air, it vaporizes and finally begins to burn as the self-ignition temperature is reached. Additional fuel is injected during the compression stroke and the fuel burns almost instantaneously, once the initial flame has been established. Thus, a period of time elapses between the beginning of fuel injection and the appearance of a flame in the cylinder. This period is commonly called “ignition delay” and must be relatively short in order to avoid “diesel knock”. A major contributing factor to diesel fuel performance and the avoidance of “diesel knock” is the cetane number of the diesel fuel. Diesel fuels of higher cetane number exhibit a shorter ignition delay than do diesel fuels of a lower cetane number. Therefore, higher cetane number diesel fuels are desirable to avoid diesel knock. Most diesel fuels possess cetane numbers in the range of about 40 to about 55. A correlation between ignition delay and cetane number has been reported in “How Do Diesel Fuel Ignition Improvers Work” Clothier, et al., Chem. Soc. Rev, 1993, pg. 101-108, the entire teachings of which are incorporated herein by reference. Cetane improvers have been used for many years to improve the ignition quality of diesel fuels.
Detergents are additives which can be added to hydrocarbon fuels to prevent or reduce deposit formation, or to remove or modify formed deposits. It is commonly known that certain fuels have a propensity to form deposits which may cause fuel injectors to clog and affect fuel injector spray patterns. The alteration of fuel spray patterns can result in non-uniform distribution and/or incomplete atomization of fuel resulting in poor fuel combustion. The accumulation of deposits is characterized by overall poor drivability including hard starting, stalls, rough engine idle and stumbles during acceleration. Furthermore, if deposit build up is allowed to precede unchecked, irreparable harm may result which may require replacement or non-routine maintenance. In extreme cases, irregular combustion could cause hot spots on the pistons which can result in total engine failure requiring a complete engine overhaul or replacement.
Dyes and Markers are materials used by the EPA (Environmental Protection Agency) and the IRS (Internal Revenue Service) to monitor and track fuels. Since 1994 the principle use for dyes in fuel is attributed to the federally mandated dying or marking of untaxed “off-road” middle distillate fuels as defined in the Code of Federal Regulations, Title 26, Part 48.4082-1(26 CFR 48.4082-1). Dyes are also used in Aviation Gasoline; Red, Blue and Yellow dyes denote octane grade in Avgas. Markers are used to identify, trace or mark petroleum products without imparting visible color to the treated product. One of the main applications for markers in fuels is in Home Heating Oil.
Anti-Icing Additives are mainly used in the Aviation industry and in cold climates. They work by combining with any free water and lowering the freeze point of the mixture to inhibit ice crystal formation.
Biocides are used to control micro organisms such as bacteria and fungi (yeasts, molds) which can contaminate fuels. The causes of Micro-Organism problems in fuels are generally attributed to fuel system cleanliness, specifically water removal from tanks and low point in the system.
Demulsifiers/Anti Haze additives are mainly added to the fuel to combat cloudiness problems which can be caused by the distribution of water in a wet fuel by dispersant used in stability packages.
The general chemistries and compositions of these additive families which function to impart the desired fuel characteristics are fully known in the art. A persons having ordinary skill in the art to which this invention pertains can readily select an additive to achieve the enhancement of the desired fuel property.
ExamplesThe present invention addresses the various causes (environmental and fuel factors) of degradation associated with storage and in-use instability of Bio feed stocks and Bio/Petroleum fuel blends. The invention by the use of a specifically chosen additive types or families (Free Radical Chain Termination Agents, Free Radical Decomposition Agents, Acid Scavengers, Photochemical Stabilizers, Gum Dispersants, and Metal Sequestering Agents) is designed to counteract or eliminate various specific modes/degradation pathways responsible for fuel instability.
The invention is further described by the following illustrative but non-limiting examples. The examples depict the effects of the various components (Free Radical Chain Termination Agents, Peroxide Decomposition Agents, Acid Scavengers, Photochemical Stabilizers, Gum Dispersants, and Metal Sequestering Agents) of the Multifunctional Stabilizer Package on in-storage and in-use stability of Bio and Bio/Petroleum fuels blends.
The oxidative stressing apparatus used to qualitatively rate Renewable Fuels, blends of Renewable Fuels and Petroleum Fuels, and additives for such fuels was developed in house. The apparatus is depicted in
In-House Oxidation Apparatus: The oxidation testing apparatus is composed of a constant temperature oil bath (to stress the samples in order to accelerate oxidative degradation), test tubes (containing the Bio or Bio Petroleum blends), and a air delivery system (composed of a gas flow regulator, to control the
The In-House method was used to demonstrate the stability enhancement of additive components on Bio, and Bio/Petroleum fuel blends.
Free Radical Chain Termination Agents
The delay on free radical propagation and its subsequent affect on bio fuel stability were examined. Test tubes containing Soy B100 and 100 mg/l of FRCTA were stressed using the In-House stability method. The samples were then evaluated using the UV analysis method for fuel stability. Results are shown in
The data in
Peroxide Decomposition Agents
The affect of peroxide decomposition on bio fuels stability was evaluated. Test tubes containing the soy B 100 and stability additives (%) were prepared as per Table 2.
The Soy B 100 samples were stressed using the In-House stability method. The samples were then evaluated using the UV analysis method for fuel stability.
The data in
Acid Scavengers
The affect of acid concentration on bio fuels stability was evaluated. The acidity diminished bio diesel was prepared by neutralizing a Soy B 100 with 0.06 N NaOH. The acid value of the starting Soy and acid diminished Soy were 0.66 mg KOH/g and 0.22 mg KOH/g respectively. Test tubes containing the two soy B 100's and stability additives (%) were prepared as per Table 3.
The Soy B 100 samples were stressed using the In-House stability method. The samples were then evaluated using the UV analysis method for fuel stability.
The data in
Photochemical Stabilizers
The affect of light on bio diesel stability was evaluated by photolizing a set of tubes containing B 100 Soy samples some of which were additized (%) as per Table 4.
The test tubes marked xx were exposed to sunlight (stored in a sunny window). The remaining tube (5) was wrapped with aluminum foil to protect against light exposure. All the tubes were left open to air. After two weeks of exposure to sun light, the contents of the tubes were stressed using the In-House stability method. The test tubes were sampled every two hours and evaluated using the UV analysis method for fuel stability.
The data in
As a concurrent experiment, the affects of aging (exposure to air) was also evaluated. A set of test tubes containing B 100 Soy samples were additized (%) as per Table 5.
The test tubes marked xx was exposed to sunlight (stored in a sunny window). The remaining tubes (2, 3, and 4) were wrapped with aluminum foil to protect against light exposure. All the tubes were left open to air. After two weeks of exposure the contents of the tubes were stressed using the In-House stability method. The tubes were sampled every two hours and evaluated using the UV analysis method for fuel stability.
The data in
Metal Sequestering Agents
The affect of metal (Copper) contamination on bio fuels stability was evaluated. Test tubes containing B 100 soy and additives (%) were prepared as per Table 6.
The Soy B 100 samples were stressed using the In-House stability method. The samples were then evaluated using the UV analysis method for fuel stability.
The data in
The examples presented clearly indicate that there are many factors which contribute to diverse mechanisms of instability of Bio fuels and Bio/Petroleum fuel blends. Therefore, it is critical to properly select and combine additives to adequately address these diverse instability processes.
While certain preferred embodiments of the present invention have been disclosed in detail, it is to be understood that various modifications may be adopted without departing from the spirit of the invention or scope of the following claim.
Claims
1) A fuel composition comprising:
- a. a Renewable Bio Feedstock Component,
- b. a Petroleum Based Component, and
- c. a Multifunctional Stabilizer Package.
2) The fuel composition of claim 1, wherein said Renewable Bio Feedstock Component is characterized as a bio diesel which is the product of trans-esterification of naturally occurring whole oils of plants or animals with an alcohol, or the ester of a fatty acid derived from naturally occurring oils, and an alcohol.
3) The fuel composition of claim 2, wherein said natural oils are selected from the group consisting of Soy, Palm, Rapeseed, Linseed, Coconut, Corn, Cotton, Cooking, Sunflower, Safflower, Tallow, Lard, Yellow Grease, Fish Oils and blends thereof.
4) The fuel composition of claim 2, wherein said alcohol is selected from the group consisting of linear, branched, alkyl, aromatic, primary, secondary, tertiary, and polyols.
5) The fuel oil composition of 1, wherein said Petroleum Based Component is described as a middle distillate fuel, a heavy fuel oil, a jet fuel or a Fischer-Tropsch fuel.
6) The fuel oil composition of claim 1, wherein said Petroleum Based Component of the fuel oil contains less then about 5000 ppm by mass of Sulfur.
7) The fuel oil composition of claim 1, wherein said Petroleum Based Component of the fuel oil contains less then about 500 ppm by mass of Sulfur.
8) The fuel oil composition of claim 1, wherein said Petroleum Based Component of the fuel oil contains less then about 17 ppm by mass of Sulfur.
9) The fuel oil composition of claim 1, wherein the said Renewable Bio Feedstock Component content of the fuel is between about 0%-to about 100% by volume of the finished fuel.
10) The fuel oil composition of 1, wherein said Renewable Bio Feedstock Component content of the fuel is between about 1%-to about 30% by volume of the finished fuel.
11) The fuel oil composition of claim 1, wherein said Petroleum Based Component content of the fuel is between about 0.1% to about 100% by volume of the finished fuel.
12) The fuel oil composition of claim 1, wherein said Petroleum Based Component content of the fuel is between about 70% to about 99% by volume of the finished fuel.
13) The fuel oil composition of claim 1, wherein said Multifunctional Stabilizer Package is described as a suitable combination of one or more members of the group consisting of:
- a. a Free Radical Chain Termination Agent,
- b. a Peroxide Decomposition Agents,
- c. an Acid Scavenger,
- d. a Photochemical Stabilizer,
- e. a Gum Dispersant, and
- f. a Metal Sequestering Agent.
14) The fuel oil composition of claim 13, wherein said Free Radical Chain Termination agent is selected from the group consisting of alkyl phenols, alkyl phenylenediamines, quinones, and nitro compounds.
15) The fuel oil composition of claim 13, wherein said alkyl phenols are selected from the group consisting of Alkyl phenols (2,6-di-tertbutyl phenol, 2,6-di-t-butyl-4-methylphenol (BHT), 2,4-dimethyl-6-t-butylphenol, tert-butyl-4-hydroxyanisole (BHA)); dihydroxy benzenes (1,4-dihydroxy benzene 1,3-dihydroxy benzene, 1,2-dihydroxybenzene); trihydroxy benzenes (1,2,3 trihydroxy benzene); poly cyclic aromatics containing one to three hydroxyl groups and gallic acid derivatives (Octyl Gallate).
16) The fuel oil composition of claim 13, wherein said alkyl phenylenediamines are selected from the group consisting of (N,N′-di-sec-butyl-p-phenylenediamine and N-sec-butyl-p-phenylenediamine.
17) The fuel oil composition of claim 13, wherein said quinones compounds are selected from the group consisting of 2,3,5-Trimethylbenzoquinone, 2,3-Dimethylbenzoquinone, 2,3-Dimethoxy-5-methylbenzoquinone, 2-Methylnaphthoquinone, t-butylhydroquinone (TBHQ).
18) The fuel oil composition of claim 13, wherein said nitro compounds are selected from the group consisting of Nitro Benzene, Di-Nitrobenzene, Nitro-Toluene, Nitro-Napthalene, and Di-Nitro Napthalene.
19) The fuel oil composition of claim 13, wherein said Peroxide Decomposition Agents are selected from the group containing Sulfur, Nitrogen and Phosphorus compounds.
20) The fuel oil composition of claim 13, wherein said Nitrogen compounds are represented by the general formula: wherein,
- R, R′, R″ can be alkyl-linear, branched, saturated, unsaturated C1-30, aromatic, cyclic, poly alkoxy, poly-cyclic;
- R, R′ can also contain other hetero atoms such as O, N, S, and P, and their resultant functional groups;
- R and R′ can be alternatively incorporated in a cyclic system containing 3 to 12 atoms.
21) The fuel oil composition of claim 13, wherein said Acid Scavengers are selected from the group consisting of primary, secondary and tertiary amines, and their derivatives
22) The fuel oil composition of claim 13, wherein said Acid Scavengers are represented by general formula: wherein,
- R, R′ can be H, alkyl-linear, branched, saturated, unsaturated, C1-30; aromatic, cyclic, poly alkoxy and carbonyl,
- R, R′ can also contain other hetero atoms such as O, N, S, and P, and their resultant functional groups,
- R′ and R′ can be incorporated in a cyclic system containing 3-12 members
- Z can be R or
- X can be 1-6, and
- Y can be 1-6.
23) The fuel oil composition of claim 13, wherein said Photochemical Stabilizer is selected from the group consisting of hindered amine light stabilizers.
24) The fuel oil composition of claim 13, wherein said Gum Dispersant is a polymeric dispersants selected from the group consisting of the polymers of: ethylene and unsaturated esters; vinyl alcohols, vinyl ethers and their ester with organic acids; propylene, ethylene, isobutylene adducts with unsaturated carboxylic acids (such as maleic and fumaric acids) and their amide or imide derivatives; acrylic acids and their amide or esters derivatives; poly styrenes; and polymers made from combinations of these monomers.
25) The fuel oil composition of claim 13, wherein said Metal Sequestering Agents are selected from the group consisting of DMD, Citric acid, and Ethylene diamine tetraacetic Acid (EDTA).
26) The fuel oil composition of claim 13, where in said Metal Sequestering Agent is DMD.
27) The fuel oil composition of claim 13, wherein said Free Radical Chain Termination Agent is present in the formulation between about 0 to about 100%, said Free Radical Decomposition Agent is present in the formulation between 0-100%, said Photochemical Stabilizer about 0.0 to about 100%, and said Metal Sequestering Agent is present in the formulation between about 0 to about 25% of said Multifunctional Stabilizer Package.
28) The fuel oil composition of claim 13, wherein said Free radical Chain Termination Agent is preferably present in the formulation between about 25 to about 85%, said Free radical Decomposition Agent can be present in the formulation between about 15 to about 65%, said Photochemical Stabilizer preferably present in the formulation between about 0.0 to about 10%, and said Metal Sequestering Agent can be present in the formulation between about 1 to about 3% of said Multifunctional Stabilizer Package.
29) The fuel oil composition of claim 13, additionally comprising or obtainable by mixing the additive(s) with carriers or diluents.
30) The fuel oil composition of claim 13, wherein said carriers and diluents are selected from the group consisting of aromatic, aliphatic hydrocarbons; alcohols; and carbonyl containing material such as aldehydes, ketones, esters, and amides.
31) A method of increasing the storage stability of a renewable fuel by metering into the renewable fuel, the Multi Functional Stabilizer Package up to 3% by volume of the renewable fuel.
32) A method of increasing the storage stability of a fuel composition by metering into the Bio/Petroleum fuel blends the Multi Functional Stabilizer Package up to 3% by volume of the Bio/Petroleum fuel blend.
33) The fuel composition of claim 1, in combination with additives selected from the group consisting of, (a) static dissipaters/electrical-conductivity improver additive, (b) low temperature operability/cold flow additives, (c) corrosion inhibitors, (d) lubricity improvers, (e) cetane improvers, (f) detergents, and (g) dyes and markers.
34) A method of operating an internal combustion engine such as a compression-ignition engine using, as fuel for the engine, a fuel oil composition of claim 1.
35) The method of claim 34, wherein said selected fuel oil has a composition of about 1% to about 30% bio component with the remainder being a Petroleum Component.
36) The method of claim 34, wherein said Petroleum Component of the Bio/Petroleum blends is a middle distillate fuel containing less than 500 ppm by mass of sulphur.
Type: Application
Filed: Jul 11, 2006
Publication Date: Dec 10, 2009
Applicant: INNOSPEC, INC. (Littleton, CO)
Inventor: Cenk R. Burgazli (Middletown, DE)
Application Number: 12/373,137
International Classification: C10L 1/19 (20060101);
