Patent Application
20240318085
Embodiments of the present disclosure generally relate to biofuels. More particularly, embodiments relate to biokerosene or biojet fuel from oxidation products of oleic oil.
The utilization of fossil energy has resulted in global warming and other environmental problems. Petroleum-based products account for about 45% of total carbon dioxide emissions in the United States. Diesel fuels, in particular, account for about 17% of total carbon dioxide emissions. Biodiesel and renewable diesel have been considered as solutions to reduce emissions. However, biodiesel use is constrained by poor low-temperature performance, making them unsuitable for cold winter seasons or jet fuel. On the other hand, renewable diesel is also challenged by the high operating temperatures and pressure, high energy consumption in production and fractionation, high demand for hydrogen sources, etc.
The utilization of petroleum also generates other environmental issues. Carbon sequestration by replacing petroleum with renewable feedstocks is viewed as a solution to inhibit global warming, as carbon dioxide emission decreases with increased biofuel production. Petroleum-based diesel fuels, including kerosene and jet fuel, account for about 17% of the total carbon dioxide emissions in the United States. Biodiesel, renewable diesel, and sustainable aviation fuel (SAF) are alternatives to diesel fuels, but their feedstocks and production routes differ. Fats/oils can be used to produce renewable diesel, SAF, or biodiesel, but biomass-derived syn-gas, biomass-derived sugars, and biomass-derived alcohols can be converted to renewable diesel or SAF.
The state-of-the-art technologies for biodiesel production depend on a feedstocks' free fatty acid (FFA) levels. For feedstocks with low FFA (≤2%), fats/oils react with alcohols under catalytical conditions to form fatty acid esters (FAEs) through direct transesterification. FAEs are called biodiesel as they can be used in the diesel engine directly or can be blended with petroleum diesel. For feedstocks with high FFA content (>2%), it is necessary to carry out the esterification of FFA to inhibit saponification before transesterification. Renewable diesel (also called green diesel) is produced from fats/oils, including fats/oils with high FFA content, through hydrogenation, deoxygenation, isomerization, and thermally/catalytically cracking. Because the carbon chain length of the typical hydrocarbons from fats/oils ranges from 15 to 18, the high melting points of these hydrocarbons result in poor low-temperature performance. The thermal/catalytic cracking and isomerization to form shorter carbon-chain length hydrocarbons and iso alkanes with good low-temperature performance are required to meet the specification of the resulting green/renewable diesel for winter season use, kerosene, or aviation fuels.
Biomass is another primary feedstock for renewable diesel and SAF, and the synthesis routes are based on three derived secondary feedstocks: syn-gas, alcohols, and sugars. Biomass-derived syn-gas can directly synthesize the hydrocarbons through the Fischer-Tropsch process with hydrogen. Bio-alcohols, such as bioethanol, biobutanol, and bio-isobutanol, produced from biomass-derived sugars via fermentation, or syn-gas from biomass pyrolysis via thermal/catalytic reforming or gas fermentation can be used as feedstock for an alternative route to renewable diesel or SAF. Alcohols are converted into alkenes by catalytic dehydration, and these alkenes are oligomerized to compounds that can be hydrogenated to hydrocarbons of size ranges found in various petroleum-based fuels. Biomass-derived sugars also can be fermented to farnesane which can be converted into hydrocarbons through hydrotreating, or are directly hydrotreated to hydrocarbons. These hydrocarbons need to be fractionated into naphtha, diesel, kerosene, and aviation fuels due to the widespread carbon chain length of hydrocarbons.
While the renewable diesel processes take advantage of a wide range of molecules and properties to approach a true drop-in replacement to petroleum diesel, the high energy consumption, high-temperature operation, high-pressure operation, demand for fractionation to specific products, low yield of target products, high capital cost, and additional hydrogen production have thus far limited adoption of these technologies. Furthermore, low-temperature performance issues mainly constrain biodiesel as the alternative to winter-season diesel, kerosene, and jet fuel. Previous studies show that biodiesel fractionation is the best way to improve low-temperature performance, and urea inclusion fractionation is the most efficient fractionation method in separation efficiency and energy efficiency. However, fractionated products result in decreased oxidation stability, increased nitrogen oxides emissions, decreased cetane number, etc.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are, therefore, not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. It is emphasized that the figures are not necessarily to scale and certain features and certain views of the figures can be shown exaggerated in scale or in schematic for clarity and/or conciseness.
Biofuels, including biodiesel, biokerosene and bio jet fuels, from oxidation products of oleic oil, methods and systems for making same are provided herein. It has been surprisingly discovered that alternatives, or blend components thereof, for winter-season diesel, kerosene, and/or jet fuels can be produced from various alcohols and nonanoic acid, a primary product from the ozonolysis of oleic acid. The products exhibit excellent low-temperature performance and show the potential for replacing winter-season diesel, kerosene, and jet fuels. Cloud points of the nonanoic esters can range from −35° C. to −70° C. These products also exhibit excellent oxidation stability and have low greenhouse gas emissions. The energy densities of the nonanoic esters increase with the carbon atoms in the alcohols and are less than current biodiesel. The nonanoic esters generally have a flash point higher than 90° C., indicating safer handling and storage. Compared to current biodiesel, the nonanoic esters have no issues with the cold soak filtration test. Cetane tests show the nonanoic esters products have reasonable values to meet various industry specifications.
In one embodiment, the method for making a biofuel includes reacting nonanoic acid with one or more alcohols to esterify the nonanoic acid to form a fatty acid ester therefrom, wherein the fatty acid ester has a cloud point of −35° C. to −70° C.
In another embodiment, the method for making a biofuel includes oxidizing oleic oil to produce nonanoic acid, and then esterifying the nonanoic acid with one or more alcohols having 1 to 28 carbon atoms to form a fatty acid ester having a cloud point of −35° C. to −70° C. and a flash point of at least 90° C.
The fatty acid ester can have a flash point of 90° C. or more. The nonanoic acid is preferably an oxidation product of a high oleic oil. The high oleic oil can be oxidized using ozonolysis to produce the nonanoic acid. The one or more alcohols can be derived from a syngas. The one or more alcohols can be or can include linear or iso alcohols or both linear and iso. The one or more alcohols can have 1 to 28 carbon atoms, such as 1 to 16 carbon atoms; 1 to 12 carbon atoms; 1 to 6 carbon atoms; 2 to 12 carbon atoms; 2 to 10 carbon atoms; or 2 to 8 carbon atoms. The one or more alcohols can be or can include a n-alcohol having 1 to 12 carbon atoms. The one or more alcohols also can be or can include a n-alcohol having 1 to 6 carbon atoms. The one or more alcohols also can be or can include an iso-alcohol having 1 to 12 carbon atoms. The one or more alcohols also can be or can include an iso-alcohol having 1 to 6 carbon atoms.
It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure can repeat reference numerals and/or letters in the various embodiments and across the figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations. Moreover, the exemplary embodiments presented below can be combined in any combination of ways, i.e., any element from one exemplary embodiment can be used in any other exemplary embodiment, without departing from the scope of the disclosure.
Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities can refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function.
Furthermore, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” The phrase “consisting essentially of” means that the described/claimed composition does not include any other components that will materially alter its properties by any more than 5% of that property, and in any case does not include any other component to a level greater than 3 mass %.
Unless otherwise indicated, all numerical values are “about” or “approximately” the indicated value, meaning the values take into account experimental error, machine tolerances and other variations that would be expected by a person having ordinary skill in the art. It should also be understood that the precise numerical values used in the specification and claims constitute specific embodiments. Efforts have been made to ensure the accuracy of the data in the examples. However, it should be understood that any measured data inherently contains a certain level of error due to the limitation of the technique and/or equipment used for making the measurement.
The term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.
The indefinite articles “a” and “an” refer to both singular forms (i.e., “one”) and plural referents (i.e., one or more) unless the context clearly dictates otherwise. For example, embodiments using “an olefin” include embodiments where one, two, or more olefins are used, unless specified to the contrary or the context clearly indicates that only one olefin is used.
The term “wt %” means percentage by weight, “vol %” means percentage by volume, “mol %” means percentage by mole, “ppm” means parts per million, and “ppm wt” and “ppmw” are used interchangeably and mean parts per million on a weight basis. All concentrations herein, unless otherwise stated, are expressed on the basis of the total amount of the composition in question.
The term “high oleic acid” means an oil or oily mixture that contains at least 75 wt % of oleic acid. Suitable high oleic acids for use herein can also contain at least 80 wt %, at least 85 wt %, at least 90 wt %, at least 93 wt %, at least 95 wt %, at least 97 wt %, or at least 99 wt %. of oleic acid The concentration of oleic acid in the high oleic acid can also range from a low of about 75 wt %, 78 wt %, or 82 wt % to a high of about 88 wt %, 90 wt %, or 95 wt %. In some embodiments, the high oleic acid consists of oleic acid or consists essentially of oleic acid. For example, in certain embodiments, suitable high oleic oils can be or can include soybean oil, canola oil, safflower oil, sunflower oil, olive oil and combinations or blends thereof. The high oleic oils can be raw, unrefined, refined, processed, used, unused, and/or recycled.
The terms “low saturated free fatty acid” and “low saturated FFA” are interchangeable and both mean less than 10 wt % of saturated free FFA, or less than 8 wt % or less than 5 wt %, or less than 3 wt %, or less than 2 wt % or less than 1 wt %. A low saturated free fatty acid (FFA) can also have a saturated FFA content that ranges from a low of 0.01 wt %, 0.05 wt %, or 1.0 wt % to a high of 3 wt %, 7 wt % or 10 wt %.
The terms “low polyunsaturated free fatty acid” and “low polyunsaturated FFA” are interchangeable and both mean less than 20 wt % of polyunsaturated FFA, or less than 18 wt % or less than 15 wt %, or less than 13 wt %, or less than 21 wt % or less than 10 wt %. A low polyunsaturated free fatty acid (FFA) can also have a polyunsaturated FFA content that ranges from a low of 1.0 wt %, 2.0 wt %, or 3.0 wt % to a high of 13 wt %, 17 wt % or 20 wt %.
Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims. Each of the inventions will now be described in greater detail below, including specific embodiments, versions and examples, but the inventions are not limited to these embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the inventions, when the information in this disclosure is combined with publicly available information and technology.
Biofuels from oxidation products of oleic oil, methods and systems for making same are provided herein. It has been surprisingly discovered that biofuel alternatives can be produced from various alcohols and nonanoic acid, a primary product of the ozonolysis of oleic acid. The products exhibit excellent low-temperature performance and can be used as alternatives, or blend components, for winter-season diesel, kerosene, and/or jet fuels. Cloud points of the nonanoic esters can range from −35° C. to −70° C. This super low-temperature performance shows the potential for replacing winter-season diesel, kerosene, and jet fuels. These products also exhibit excellent oxidation stability and have low greenhouse gas emissions. The energy densities of the products increase with the carbon atoms in the alcohols and are less than current biodiesel. The products generally have a flash point greater than 90° C., indicating safer handling and storage. Compared to current biodiesel, the products have no issues with the cold soak filtration test. Cetane tests show that the products have reasonable values to meet various specifications around the world.
The oleic acid can be derived from any suitable animal and/or vegetable fats and oils. For example, soybean oils are oil varieties characterized by a high content of oleic acid, low saturated free fatty acid (FFA), and low polyunsaturated FFA. High oleic oils increase the stability of oil and improve human health, and industrial applications such as biofuels, and biochemicals are additional opportunities for these products.
A method for making biofuels from oleic oil, more particularly high oleic oil, is provided. In certain embodiments, high oleic oils can be oxidized through ozonolysis to dicarboxylic acids and monocarboxylic acid (e.g. nonanoic acid) with a high yield. Dicarboxylic acids have medical uses or are monomers for biomaterials through polymerization.
In certain embodiments, the feedstock is or contains nonanoic acid, which can esterify with one or more alcohols to synthesize fatty acid esters (FAEs). Nonanoic acid is a primary product of the ozonolysis of oleic acid, which is a mono-unsaturated omega-9 fatty acid found in various animal and vegetable sources.
Any suitable alcohol can be used to esterify the nonanoic acid to form the FAEs. Suitable alcohols can be linear or branched. Suitable alcohols can have 1 to 28 carbon atoms. For example, the number of carbon atoms can range from a low of 1, 2 or 3 to a high of 12, 20, or 28. Suitable alcohols can be primary, secondary or tertiary alcohols. In certain embodiments, n-alcohols and iso-alcohols having 1 to 28 carbon atoms can be used. In other embodiments, n-alcohols and iso-alcohols having 1 to 28, 1 to 20, 1 to 12, 1 to 6, or 1 to 4, or 1 to 3 carbon atoms can be used. Methanol and ethanol are preferred. Butanol and iso-butanol are also preferable.
In certain embodiments, the nonanoic acid can be reacted with one or more suitable alcohols at atmospheric pressure to form esters in the presence of an acidic or basic catalyst. The catalyst can be homogenous or heterogenous. The catalyst can be supported or unsupported. Suitable catalysts include methanesulfonic acid (MSA) and sulfuric acid. Ion exchange resins (strong acid type) can also be used. Other suitable catalysts include heterogenous catalysts, such as MgF2 and ZnF2 are also able to do this conversion.
Preferred reaction temperatures to convert the nonanoic acid to esters are about the approximate boiling points of the alcohol(s) to reach the fastest reaction rates. For example, suitable reaction temperatures include 60-70° C. for: methanol; 72-82° C. for ethanol; 92-102° C. for 1-propanol; 78-88° C. for 2-propanol; 113-123° C. for 1-butanol; 105-115° C. for iso-butanol; and 126-136° C. for iso-pentanol. Additional reaction temperatures include 65° C. for methanol; 78° C. for ethanol; 97° C. for 1-propanol; 83° C. for 2-propanol; 118° C. for 1-butanol; 108° C. for iso-butanol; and 131° C. for iso-pentanol.
The resulting FAEs exhibit excellent low-temperature performance, excellent oxidation stability, decreased nitrogen oxides emissions. These significantly improved qualities allow the FAEs to serve as biofuels, or biofuel components, and are an excellent alternative to winter-season diesel, kerosene, and aviation fuels. In addition, the production process has the potential to be more economical than renewable diesel routes due to lower capital cost, low energy consumption, high biodiesel yield, and high value of the by-products. Compared to current biodiesel and renewable diesel, the biodiesel from the proposed route results in high yields, low production costs, moderate operation conditions, high values of by-products, and uniform qualities of products. In addition, the methods provided herein also can increase sustainability by carbon sequestration because of the renewability of feedstocks.
Additional aspects of the present disclosure include the following embodiments.
Embodiment I: A method for making a biofuel, comprising reacting nonanoic acid with one or more alcohols to esterify the nonanoic acid to form a fatty acid ester having a cloud point of −35° C. to −70° C.
Embodiment II: The method according to Embodiment I, wherein the fatty acid ester has a flash point of 90° C. or more.
Embodiment III: The method according to Embodiments I or II, wherein the nonanoic acid is an oxidation product of a high oleic oil.
Embodiment IV: The method according to any of Embodiments I through III, further comprising oxidizing a high oleic oil using ozonolysis to produce the nonanoic acid.
Embodiment V: The method according to any of Embodiments I through IV, wherein the alcohol is derived from a syngas.
Embodiment VI: The method according to any of Embodiments I through V, wherein the one or more alcohols comprise a n-alcohol having 1 to 12 carbon atoms.
Embodiment VII: The method according to any of Embodiments I through VI, wherein the one or more alcohols comprise a n-alcohol having 1 to 6 carbon atoms.
Embodiment VIII: The method according to any of Embodiments I through VII, wherein the one or more alcohols comprise an iso-alcohol having 1 to 12 carbon atoms.
Embodiment IX: The method according to any of Embodiments I through VIII, wherein the one or more alcohols comprise an iso-alcohol having 1 to 6 carbon atoms.
Embodiment X: A method for making a biofuel, comprising oxidizing oleic oil to produce nonanoic acid; and esterifying the nonanoic acid with one or more alcohols having 1 to 12 carbon atoms to form a fatty acid ester having a cloud point of −35° C. to −70° C. and a flash point of at least 90° C.
Embodiment XI: The method according to Embodiment X, therein the one or more alcohols are linear alcohols.
Embodiment XII: The method according to Embodiments X or XI, therein the one or more alcohols are iso-alcohols.
Embodiments discussed and described herein can be further described with the following examples. Although the following examples are directed to specific embodiments, they are not to be viewed as limiting in any specific respect.
Esterification of Nonanoic Acid with Various Alcohols
Esterification reactions were performed in a Soxhlet extraction system (24005-50, Kimble Kontes) with a 1 L flask. The flask was heated by a heating mantle with an adjustable voltage power supply (Superior Electric Co.), and the condenser of the Soxhlet extraction system was controlled by a refrigerated circulator (RTE-111, NESlab) at 1° C. The alcohols used in this study included: methanol (≥99.9%, Sigma Aldrich Inc.), 200 proof ethanol (100%, Decon Laboratories Inc.), 1-propanol (≥99.9%, Sigma Aldrich Inc.), 2-propanol ((≥99.9%, Sigma Aldrich Inc), 1-butanol (99.9%, Sigma Aldrich Inc.), iso-butanol (≥99.9%, Supelco Inc.), and isopentanol (≥99.9%, Sigma Aldrich Inc.).
Nonanoic acid (≥96%, Sigma Aldrich Inc.) was reacted with the alcohols at atmospheric pressure to form esters in the presence of methanesulfonic acid (MSA, 70%, Sigma Aldrich Inc.) as the homogenous catalyst. The reactions occurred at the approximate boiling points of alcohols to reach the fastest reaction rates and the reaction temperatures are listed as: methanol: 65° C., ethanol: 78° C., 1-propanol: 97° C., 2-propanol: 83° C., 1-butanol: 118° C., iso-butanol: 108° C., isopentanol: 131° C. In addition, 4 Å molecular sieves were used as the desiccant to remove the extra water generated during the reaction. For a specific experiment, 0.7 moles of nonanoic acid, 4.2 moles of specific alcohol, and 0.014 moles of MSA (1.92 g of 70% MSA) were poured into the 1 L flask. 63 g of 4 Å molecular sieves was put into the thimble of the Sohlex system. After the solution mixture was boiled for 6 hours, the extra alcohol was evaporated by a rotary evaporator. Then, the residual mixture was poured into a 1 L separation funnel, and 100 ml of hexane and 200 ml of deionized water were added and vigorously mixed. The mixture was allowed to settle for 30 mins before the layers were separated. The previous hexane/water extraction step was repeated until the aqueous layer became clear and pH difference between the aqueous layer and de-ion water was less than 0.5. The top organic mixture was poured into a 1 L flask, and hexane/water was removed to obtain the purified esters. The purified esters were analyzed and characterized by various tests, such as FTIR, cloud point, freezing point, density, viscosity, and combustion heat.
FTIR analysis was performed by a Nicolet Nexus FTIR (Thermo Fisher Scientific, USA), and the samples were analyzed in a spectral region between 4000 and 800 cm 1 with a 2 cm 1 resolution. The samples for FTIR analysis included nonanoic acid, alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, iso-butanol, and iso-pentanol), and esters formed by nonanoic acid with various alcohols.
About 5 mL of the reaction mixtures were taken at specific intervals during the reactions and the reaction in the sample was quickly quenched by ice. The GC analysis samples were prepared by diluted the reaction mixture to hexane at the ratio of 1:5. Samples were analyzed using a gas chromatograph (Agilent 7820A) equipped with a flame ionization detector and a CP-Sil88 capillary column (50 m, 0.25 m i.d. and 0.2-μm film thickness. Detector and injector were set at 280° and 285° C., respectively. The oven program was as follows: 80° C. held for 2 min, then increased at 6° C./min to 120° C. and held for 1 min, then increased to 185° C. at 10° C./min and held for 1 minute, then heated to 225° C. and held for 2 minutes. Helium was used as carrier gas at a constant flow of 2.5 ml min-1. Injection volume was of 1 μL in split mode with a split ratio of 20:1.
Cloud point was measured according to the ASTM D 2500. In the cloud point detection, a stainless steel cylinder was immersed in the ethanol bath, and the temperature was chilled by adding dry ice. A glass test tube with about 25 mL moisture-free sample was settled into the cylinder. The cloud point was recorded as the temperature of observing waxy clouds or haze.
The densities and viscosities were measured by a Stabinger viscometer (SVM 3001, Anton Paar) at −20° C., 15° C., and 40° C. according to ASTM D 4052 and D 7042, respectively. Toluene was used as solvent between injections to clean the system, and the instrument was calibrated and checked for accuracy using APS3 and APN2B Anton Paar-certified standards.
Combustion heats of FAEs were detected by a calorimeter (Isoperibol 6200, Anton Paar) with a water handling system according to ASTM D 4809. The combustion heat was measured by burning the equivalent mass to 0.7 ml of each sample in a bomb calorimeter filled with pure oxygen at 450 psi. The increment in the temperature of the water surrounding the bomb after ignition and complete combustion was automatically correlated, corrected, and reported by the system.
Cetane numbers were calculated according to ASTM D 613 by Southwest Research Institute and using the equation below. The samples were used to rinse the engine tank and fuel line before testing. The fuel flow rate was set at 13 mL per min, and the injection-timing-micrometer of the fuel pump assembly was adjusted for obtaining a 13.0°+0.2° injection advance reading. Then, the handwheel was adjusted to change the compression ratio and obtain a 13.0°+0.2° ignition delay reading. For each fuel, equilibrium was reached and the handwheel readings were recorded.
Oxidation stability was measured according to EN 15751 by Iowa central fuel testing laboratory, a BQ-9000 fuel testing laboratory, and the testing procedure was briefly described as the following: 10 L/hour of purified air was induced into the biodiesel sample at the temperature of 110° C. The air carried the volatile organics from the oxidation to the container with distilled water. The conductivity of the water solution was continuously recorded, and the oxidation stability in hours was the time when the conductivity rapidly changed.
Cold soak filtration test was performed according to ASTM D 7501. Biodiesel was warmed without heating to room temperature after being stored at 4±0.5° C. for 16 hours. Then, 300 mL of biodiesel was filtered through a 0.7 μm glass fiber filter under a vacuum of 21 to 25 in Hg. The filtration time was recorded, and the allowed maximum filtration time was 360 seconds.
A 100 mL sample was poured into a 250 mL two-neck flask and heated with a heating mantle. A type K thermometer was put into the liquid without touching the glass. One neck was open to keep the pressure at 1 atm. When the liquid started boiling, the temperature was recorded, and the boiling point was the temperature without changing for 1 hour.
Biodiesel Production from Nonanoic Acid and Various Alcohols
Nonanoic acid reacts with various alcohols to form esters that can be used as fuels in diesel engines. The hydroxyl group in the carboxylic acids and hydrogen formed water, while the carbonyl group bonded to the alcohol group to form esters in the esterification process. FITR analysis of the reaction mixtures over time showed ester group formation (in
One major challenge for current biodiesel is the poor low-temperature performance, and the cloud point appropriately shows the low-temperature performance based on the thermodynamic phase change. Cloud points of current biodiesel range from −3 to 23° C. depending on the feedstock, indicating not being used in the winter season, while the cloud points of #2 winter season diesel for North America range from −7 to −28° C., and the cloud point of jet fuel is −40° C. In addition, jet fuel has maximum freezing points of less than −40° C. Therefore, it is necessary to develop renewable alternatives to winter-season diesel or jet fuel, such as biokerosene. The measured cloud points of biokerosene formed by nonanoic acid and various alcohols ranged from −35° C. to −67° C., depending on the type of alcohol used in synthesis. After storage of 72 hours under various temperatures, all fuel samples remained liquid at these temperatures except methyl nonanoate (MNE) at −40° C. storage. The biokerosene's cloud points depended on the alcohol's structures. For biokerosene synthesized with n-alcohols, the cloud points decreased significantly from MNE to ethyl nonanoate (ENE), while they slightly decreased for propyl nonanoate (PNE) and butyl nonanoate (BNE) compared to ENE. For biokerosene synthesized with iso-alcohols, the cloud points significantly decreased from iso-propyl nonanoate (IPNE) to iso-butyl nonanoate (iBNE) and iso-pentyl nonanoate (iPENE). Biokerosene synthesized with iso-alcohols resulted in lower cloud points because the isomerization resulted in less effective intermolecular to pack them together in the crystallization process. In order to improve the low-temperature performance, the effect of alkyl isomerization is more significant than hydroxyl isomerization (
Fuel density affects the volumetric energy density and kinematic viscosity. Density generally increases with temperature. For biokerosene synthesized from n-alcohols, MNE has the highest density, while ENE has the lowest density. Isomerization of alcohol resulted in slightly decreased density because of the weak intermolecular force in molecules. Diesel generally has a density of 850 kg/m3 at 15° C., while biodiesel has a density of 880 kg/m3 at 15° C. MNE has a density close to the current biodiesel that is converted from oils/fats with methanol. In this study, fuels (except MNE) had densities about 10 kg/m3 higher than diesel at 15° C.
Viscosity affects the atomization of fuel and droplet size in the combustion chamber. In addition, too high viscosity results in incomplete combustion, large-size soot formation, high greenhouse gas (GHG) emissions, and pump damage, but too low viscosity causes a lack of lubricity. MNE's viscosities are close to ENE's at the test temperatures (
Energy density is a vital parameter in evaluating fuels because it determines the available energy in the storage unit. The volumetric and gravimetric energy densities of diesel fuels are about 34.6 MJ/L and 45.4 MJ/kg, respectively. However, biodiesel's volumetric and gravimetric energy densities are about 33 MJ/L and 38 MJ/kg, respectively. According to the experimental data, the biokerosene's energy densities generally increased with carbon atoms in alcohol functional groups (
Oxidation stability indicates the storage period for fuels because the oxidation of fuels results in undesired products that impair the fuel qualities. Current biodiesel with high polyunsaturated components requires antioxidants to improve its stability. However, biodiesel made from highly saturated fatty acids, such as palm oil, does not have the oxidation stability issue. The biokerosene in this study exhibited excellent oxidation stability for over 30 hours, as shown in Table 1, since they were synthesized with saturated carboxylic acid (nonanoic acid) and saturated alcohols. The super oxidation stability made biokerosene for long-time storage and handling without degradation in quality.
Cetane number indicates the ignition delay of fuel in diesel engines. High cetane number shows short delay and complete combustion. Cetane number of the biokerosene in this study depended on the alcohol structure (
Flashpoint is a critical specification for fuel storage and handling. Fuel with a flash point below 60° C. is classified as flammable, but fuel with a flash point above 60° C. is classified as combustible. Therefore, the biokerosene produced in this study is classified as combustible (
The monoglycerides and sterol glucosides precipitate above the cloud point for the biodiesel from current feedstocks. However, the biokerosene showed no issue with the cold soak filtration test as the feedstock is the FFA instead of triglycerides. The cold soak filtration test for the typical biokerosene showed excellent performance (
Though many alcohols can be used for making esters with nonanoic acid in addition to the alcohols used in this research, the availability of the alcohols, qualities of fuels, and production cost should be considered together. The typical alcohol used in current biodiesel production is methanol for its low price, large availability, and low production cost. However, methanol is mainly produced from the chemical synthesis of petroleum-based materials. Therefore, the renewability of biofuel from methanol is reduced. Another largely available alcohol is ethanol, mainly produced from via fermentation. The annual production rate in the United States is over 16 billion gallons. In addition, n-butanol and iso-butanol also can be produced from the fermentation process. These fermentation processes for bio-alcohol production are characterized by low concentrations in the broth, such as 1-14% bioethanol in broth and less than 1% butanol in broth. Since distillation is commonly used for alcohol recovery, energy consumption dramatically increases with the decreased feed concentrations. Additionally, the distillation does not obtain pure alcohol because of the azeotrope with water. Another method to obtain bio-alcohols is via pyrolysis of woody biomass under high temperatures and pressures. However, multiple alcohols are produced in this process, where ethanol is the main product. Alcohols can also be converted from syn-gas (CO+H2) by the Fisher-Tropsch process, but this energy consumption is much higher. Therefore, ENE is preferred at the current stage according to the properties of ENE and ethanol availability and renewability. Approximately 1.53 kg of oleic acid is needed to be oxidized to 1.01 kg of valuable azelaic acid and 0.85 kg of nonanoic acid, which can be converted to 1 kg of ENE biokerosene with the additional 0.25 kg of ethanol. However, BNE or iBNE will be preferred in the future with technical developments in butanol and/or iso-butanol production, especially in energy consumption improvement in the purification process. only approximately 1.33 kg of oleic acid is needed to make 1 kg of BNE or iBNE. However, the amount of butanol or iso-butanol increases to 0.35 kg.
In addition, a process is developed to synthesize renewable diesel or sustainable aviation fuel from alcohol with alcohol dehydration, oligomerization, and hydrogenation. Compared to this route, utilization of alcohols in biokerosene production is a better choice because of the following reasons: 1) no need for the expensive catalyst and the maintenance cost, 2) atmospheric pressure and low reaction temperature, 3) uniform products without the fractionation process, 4) no need for the hydrogen sources, 5) low mass fractions utilization of alcohol. Mass fraction loss of dehydration of ethanol and butanol are 40% and 25%, respectively. However, mass fraction loss in esterification for ethanol and butanol is no more than 2.2%.
Various embodiments for synthesizing biokerosene from nonanoic acid, the primary product from the ozonolysis of oleic oil obtained from high oleic soybean oil, with various alcohols are provided herein. It has been surprisingly and unexpectedly discovered that the type of alcohol used in the synthesis significantly influenced the properties of biokerosene from this process. Generally, the biokerosene synthesized according to the embodiments described herein exhibited excellent oxidation stability because of the saturation of the molecules. The excellent oxidation stability indicates stable storage of the resulting fuel without requiring the addition of antioxidants. In addition, the biokerosene synthesized according to the embodiments described herein also expressed super low-temperature performance. Biokerosene synthesized according to the embodiments described herein can be used as winter season diesel, kerosene, or jet fuel as the cloud points range from −35 to −70° C. Biokerosene synthesized according to the embodiments described herein has flash points ranging from 75° C. to 120° C., which indicates that it is safer than diesel for handling and storage. Biokerosene synthesized according to the embodiments described herein has no issue with cold soak filtration as it has no relation to the monoglycerides and sterol glucoside. Biokerosene synthesized according to the embodiments described herein expresses sufficient or better cetane numbers that methyl ethers. Methyl esters need cetane improvers to have no issue of ignition delay in the engine.
The energy density satisfies the minimum energy density (35 MJ/kg) for diesel fuel. Based on the current alcohol availability, sustainability, and production cost, ethyl nonanoate is the best choice at the current stage. With energy-efficient separation technology development, such as ultrasonic separation and process intensification, butyl nonanoate or iso-butyl nonanoate may become the predominant biodiesel for the winter season or jet fuel in the future. Moreover, biokerosene can be a better route than renewable diesel from alcohol to replace petroleum-based jet fuel or winter season diesel fuel.
In other embodiments, nonanoic acid production from high oleic oils that is mainly triglycerides are provided herein. Triglycerides can be converted to fatty acid esters with alcohols using a base or acid catalyst through transesterification. Methanol takes the advantage over other alcohol for its low cost and is mainly used in current industrial biodiesel production. Therefore, the biodiesel is also called fatty acid methyl esters (FAMEs). The biodiesel can be fractionated by urea inclusion to remove the saturated components to obtain the unsaturated components. The unsaturated components, such as methyl oleate, can be converted to nonanoic acid and mono methyl azelaic acid by ozonolysis. This process can occur at room temperature. The obtained nonanoic acid can react with various alcohols to produce biokerosene as previously described. This route is shown in
All patents and patent applications, test procedures (such as ASTM methods, UL methods, and the like), and other documents cited herein are fully incorporated by reference to the extent such disclosure is not inconsistent with this disclosure and for all jurisdictions in which such incorporation is permitted.
Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and/or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are “about” or “approximately” the indicated value, meaning the values take into account experimental error, machine tolerances and other variations that would be expected by a person having ordinary skill in the art.
The foregoing has also outlined features of several embodiments so that those skilled in the art can better understand the present disclosure. Those skilled in the art should appreciate that they can readily use the present disclosure as a basis for designing or modifying other methods or devices for carrying out the same purposes and/or achieving the same advantages of the embodiments disclosed herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure, and the scope thereof is determined by the claims that follow.
Various terms have been defined above. To the extent a term used in a claim is not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure is not inconsistent with this application and for all jurisdictions in which such incorporation is permitted.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims priority to U.S. Provisional Patent Application having Ser. No. 63/454,112, filed on Mar. 23, 2023. The entirety of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63454112 | Mar 2023 | US |
