Patent Application
20250188376
Embodiments herein relate to sustainable aviation fuels and methods for making the same.
Sustainable aviation fuels (SAFs) are a type of biofuel that can be used as an alternative to traditional fossil-based jet fuels. As defined by the U.S. Department of Energy, SAF is a biofuel used to power aircraft that has similar properties to conventional jet fuel but with a smaller carbon footprint. In some cases, SAFs can be blended with traditional fossil-based aviation fuel. SAFs are made from renewable sources (such as plant or animal materials), rather than fossil fuels. They can be produced from a variety of feedstocks, including agricultural and forestry waste, municipal waste, and cooking oil and animal waste fat.
The EPA has enacted the Renewable Fuel Standard (RFS2), which mandates the use of a minimum of 34.39 billion gallons of biomass-based transportation fuels by 2025. Over 28 billion gallons of jet fuel per year is consumed in the U.S. and less than 0.1% (or 15.8 million gallons) constitutes current domestic SAF production. The current U.S. SAF Grand Challenge goal is to produce 3 billion gallons of SAF by 2030 and for SAF to completely replace the 35 billion gallons of aviation fuel projected to be consumed annually by 2050.
Furthermore, the reduction of greenhouse gases and engine emissions are important goals for the improvement of air quality in the United States. Fossil fuels have detrimental effects on the environment since they release sequestered carbon compounds and other pollutants into the atmosphere. In contrast, biofuels are more environmentally friendly than fossil fuels because their use recycles carbon through biomass and because they burn cleaner than fossil fuels.
Although biodiesel has been tested as an additive to aviation fuels, it has properties that make it incompatible with turbine engines at high concentrations with one major issue being the relatively high temperature at which it freezes. Furthermore, traditional biodiesel production is also disadvantaged by use of the strong base catalyzed transesterification reaction, which sharply limits feedstock flexibility due to unwanted side reactions (such as the saponification of free fatty acids). In addition, currently used homogeneous catalysts are not reusable and must be discarded as waste from the final product streams after neutralization.
There are various challenges to overcome in producing SAFs, such as efficiently producing SAFs that meet jet fuel specifications while utilizing available feedstocks.
Embodiments herein relate to sustainable aviation fuels and methods for making the same. In a first aspect, a process for producing a sustainable aviation fuel composition can be included having mixing a lipid feedstock with at least one branched chain alcohol to form a reaction mixture, and contacting the reaction mixture with a catalyst at greater than room temperature and pressure to form reaction products, the catalyst can include at least one selected from the group consisting of alumina, titania, zirconia, and hafnia.
In a second aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include a primary alcohol.
In a third aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include a secondary alcohol.
In a fourth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include a C5 to C20 alcohol.
In a fifth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include at least one selected from the group consisting of isoheptanol, isooctanol, isononanol, and isodecanol.
In a sixth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include 2-ethyl octanol.
In a seventh aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include
wherein n can be 0 to 10, R1 can be linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne, and R2 can be linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne.
In an eighth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include a mixture of branched chain alcohols.
In a ninth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing the lipid feedstock with the at least one branched chain alcohol and at least one straight chain alcohol to form a reaction mixture.
In a tenth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing the lipid feedstock with at least one C5 or greater branched chain alcohol and at least one C4 or less straight chain alcohol to form a reaction mixture.
In an eleventh aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing the lipid feedstock with at least one C5 or greater branched chain alcohol and at least one of methanol, ethanol, propanol, or butanol to form a reaction mixture.
In a twelfth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing a lipid feedstock with at least two branched chain alcohols to form a reaction mixture, wherein the at least two branched chain alcohols have a different chain length from one another.
In a thirteenth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the lipid feedstock can include at least one selected from the group consisting of safflower oil, tall oil fatty acid, tung oil, linolenic acid, pennycress oil, coconut oil, castor oil, and flaxseed oil.
In a fourteenth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include contacting the reaction mixture with a catalyst at a pressure of 500 to 2000 PSI.
In a fifteenth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include contacting the reaction mixture with a catalyst at greater than 200° C.
In a sixteenth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include contacting the reaction mixture with a catalyst at greater than 300° C.
In a seventeenth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition can have a freezing point of −40 degrees Celsius or less.
In an eighteenth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition can have a flash point of greater than 38 degrees Celsius.
In a nineteenth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, wherein at least 10% by weight of the sustainable aviation fuel composition can have a boiling point of 205 degrees Celsius or less.
In a twentieth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, wherein substantially all of the sustainable aviation fuel composition can have a boiling point of 300 degrees Celsius or less.
In a twenty-first aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition meets Jet A standards per ASTM D1655.
In a twenty-second aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition meets Jet A-1 standards per ASTM D1655.
In a twenty-third aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition meets ASTM D7566.
In a twenty-fourth aspect, a process for producing a sustainable aviation fuel composition can be included having mixing a lipid feedstock with at least one aromatic alcohol to form a reaction mixture, and contacting the reaction mixture with a catalyst at greater than room temperature and pressure to form reaction products, the catalyst can include at least one selected from the group consisting of alumina, titania, zirconia, and hafnia.
In a twenty-fifth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the mixing the lipid feedstock with the at least one aromatic alcohol to form a reaction mixture can include a primary alcohol.
In a twenty-sixth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the mixing the lipid feedstock with the at least one aromatic alcohol to form a reaction mixture can include a secondary alcohol.
In a twenty-seventh aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the mixing the lipid feedstock with the at least one aromatic alcohol to form a reaction mixture can include a C5 to C20 alcohol.
In a twenty-eighth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the mixing the lipid feedstock with the at least one aromatic alcohol to form a reaction mixture can include benzyl alcohol.
In a twenty-ninth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing a lipid feedstock with at least two aromatic alcohols to form a reaction mixture, wherein the at least two aromatic alcohols have a different number of carbons from one another.
In a thirtieth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the lipid feedstock can include at least one selected from the group consisting of safflower oil, tall oil fatty acid, tung oil, linolenic acid, pennycress oil, coconut oil, castor oil, and flaxseed oil.
In a thirty-first aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include contacting the reaction mixture with a catalyst at a pressure of 500 to 2000 PSI.
In a thirty-second aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include can include contacting the reaction mixture with a catalyst at greater than 200° C.
In a thirty-third aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include can include contacting the reaction mixture with a catalyst at greater than 300° C.
In a thirty-fourth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include distilling the reaction products.
In a thirty-fifth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition can have a freezing point of −40 degrees Celsius or less.
In a thirty-sixth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition can have a flash point of greater than 38 degrees Celsius.
In a thirty-seventh aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, wherein at least 10% by weight of the sustainable aviation fuel composition can have a boiling point of 205 degrees Celsius or less.
In a thirty-eighth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, wherein substantially all of the sustainable aviation fuel composition can have a boiling point of 300 degrees Celsius or less.
In a thirty-ninth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition meets Jet A standards per ASTM D1655.
In a fortieth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition meets Jet A-1 standards per ASTM D1655.
In a forty-first aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable aviation fuel composition meets ASTM D7566.
In a forty-second aspect, a process for producing a sustainable fuel composition can be included having mixing a branched carboxylic acid with at least one branched chain alcohol to form a reaction mixture, and contacting the reaction mixture with a catalyst at greater than room temperature and pressure to form reaction products, the catalyst can include at least one selected from the group consisting of alumina, titania, zirconia, and hafnia.
In a forty-third aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include a primary alcohol.
In a forty-fourth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include a secondary alcohol.
In a forty-fifth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include a C5 to C20 alcohol.
In a forty-sixth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include at least one selected from the group consisting of isoheptanol, isooctanol, isononanol, and isodecanol.
In a forty-seventh aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include 2-ethyl octanol.
In a forty-eighth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include
wherein n can be 0 to 10, R1 can be linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne, and R2 can be linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne.
In a forty-ninth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the at least one branched chain alcohol can include a mixture of branched chain alcohols.
In a fiftieth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing the branched carboxylic acid with at least two branched chain alcohols to form a reaction mixture, wherein the at least two branched chain alcohols have a different chain length from one another.
In a fifty-first aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing the branched carboxylic acid with the at least one branched chain alcohol and at least one straight chain alcohol to form a reaction mixture.
In a fifty-second aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing the branched carboxylic acid with at least one C5 or greater branched chain alcohol and at least one C4 or less straight chain alcohol to form a reaction mixture.
In a fifty-third aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the method can further include mixing the branched carboxylic acid with at least one C5 or greater branched chain alcohol and at least one of methanol, ethanol, propanol, or butanol to form a reaction mixture.
In a fifty-fourth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the branched carboxylic acid can include
wherein n can be 0 to 10, R1 can be linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne, and R2 can be linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne.
In a fifty-fifth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the branched carboxylic acid can include at least one selected from the group consisting of isovaleric acid and isobutyric acid.
In a fifty-sixth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include contacting the reaction mixture with a catalyst at a pressure of 500 to 2000 PSI.
In a fifty-seventh aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include contacting the reaction mixture with a catalyst at greater than 200° C.
In a fifty-eighth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the contacting the reaction mixture with the catalyst at greater than room temperature and pressure to form reaction products can include contacting the reaction mixture with a catalyst at greater than 300° C.
In a fifty-ninth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable fuel composition can have a freezing point of −40 degrees Celsius or less.
In a sixtieth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable fuel composition can have a flash point of greater than 38 degrees Celsius.
In a sixty-first aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, wherein at least 10% by weight of the sustainable fuel composition can have a boiling point of 205 degrees Celsius or less.
In a sixty-second aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, wherein substantially all of the sustainable fuel composition can have a boiling point of 300 degrees Celsius or less.
In a sixty-third aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable fuel composition meets Jet A standards per ASTM D1655.
In a sixty-fourth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable fuel composition meets Jet A-1 standards per ASTM D1655.
In a sixty-fifth aspect, in addition to one or more of the preceding or following aspects, or in the alternative to some aspects, the sustainable fuel composition meets ASTM D7566.
This summary is an overview of some of the teachings of the present application and is not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details are found in the detailed description and appended claims. Other aspects will be apparent to persons skilled in the art upon reading and understanding the following detailed description and viewing the drawings that form a part thereof, each of which is not to be taken in a limiting sense. The scope herein is defined by the appended claims and their legal equivalents.
Aspects may be more completely understood in connection with the following figures (FIGS.), in which:
While embodiments are susceptible to various modifications and alternative forms, specifics thereof have been shown by way of example and drawings, and will be described in detail. It should be understood, however, that the scope herein is not limited to the particular aspects described. On the contrary, the intention is to cover modifications, equivalents, and alternatives falling within the spirit and scope herein.
Systems and methods herein can be used to efficiently produce reaction product mixtures that can be used as sustainable aviation fuels and/or fuel components that meet jet fuel specifications. The sustainable aviation fuels and/or fuel components can include those with remarkably low freezing points. In some embodiments, reactants can include one or more branched alcohols and a lipid feedstock. In some embodiments, reactants can include one or more aromatic alcohols and a lipid feedstock. In some embodiments, reactants can include one or more branched alcohols and one or more branched carboxylic acids. Reaction products herein can include branched chain esters that make excellent sustainable fuel components. In some embodiments, mixtures of different reactants can be selected to achieve properties in the reaction product mixtures such as specific boiling points and boiling point ranges. In some embodiments, different reaction product mixtures can be blended together to result in a sustainable fuel product meeting applicable requirements.
Referring now to
The reactants then pass through a shutoff valve 134 and a filter 136 to remove particulate material of a certain size. The reactants can then pass through a preheater 142. The preheater 142 can elevate the temperature of the reaction mixture to a desired level. Many different types of heaters are known in the art and can be used.
The reaction mixture can then pass through a reactor 144 where the reactants are converted into a reaction product mixture. The reactor can include a metal oxide catalyst, such as those described herein. The reaction product mixture can pass through the heat exchanger 132 in order to dissipate their heat. The reaction product mixture can also pass through a backpressure regulator 146. The reaction products can then pass on to a reaction product tank 150.
It will be appreciated that not all reactants may be miscible with one another. As such, in some embodiments reactants can be stored in separate tanks. Referring now to
The feedstock stream passes through a first shutoff valve 234 and a first filter 236 to remove particulate material of a certain size from the feedstock. The alcohol feedstock passes through a second shutoff valve 238 and a second filter 240. Both the feedstock and the alcohol then pass through a preheater 142 where they are mixed together to form a reaction mixture. The preheater 142 can elevate the temperature of the reaction mixture to a desired level. Many different types of heaters are known in the art and can be used.
The reaction mixture can then pass through a reactor 144 where the feedstock and alcohol are converted into a reaction product mixture. The reactor can include a metal oxide catalyst. The reaction product mixture can pass through the heat exchanger 132 in order to dissipate their heat. The reaction product mixture can also pass through a backpressure regulator 146. Optionally, in some embodiment the reaction product mixture can pass to a distillation apparatus 248. The distillation apparatus 248 can be configured to carry out fractional distillation in order to remove excess alcohol from the reaction product mixture and/or isolate a fraction of the reaction product mixture. The fractional distillation apparatus can include any desired number of theoretical plates in order to recover a desired amount of the excess alcohol and to remove any other byproducts of the reaction. In some embodiments, a ROTO-VAP apparatus under vacuum conditions can be used as part of a distillation process.
The recovered alcohol can then be put back into the alcohol tank 228 and reaction products can then pass on to a reaction product tank 150.
In various embodiments, compositions produced herein have a low freezing point. In various embodiments, compositions produced herein have a freezing point of less than −20, −25, −30, −35, −40, −42.5, −45, or −47.5 degrees Celsius.
In various embodiments, compositions produced herein have a boiling point falling within a range that is suitable for sustainable aviation fuels. For example, compositions produced herein can have a boiling point of falling within a range of less than 200 to greater than 300 degrees Celsius. In some embodiments, at least 10% by weight of the composition produced herein has a boiling point of 205 degrees Celsius or less. In some embodiments, substantially all of the composition produced herein has a boiling point of 300 degrees Celsius or less. In some embodiments, at least 97% by weight, 98% by weight, 99% by weight, 99.5% by weight, or 99.9% by weight of the composition produced herein has a boiling point of 300 degrees Celsius or less.
Embodiments of the invention can be used to produce a mixture of reaction products forming a sustainable fuel composition that meets Jet A standards per ASTM D1655. Embodiments of the invention can be used to produce a mixture of reaction products forming a sustainable fuel composition that meets Jet A-1 standards per ASTM D1655. Embodiments of the invention can be used to produce a mixture of reaction products forming a sustainable aviation fuel composition that meets ASTM D7566.
Reactions herein can take place at various temperatures. In some embodiments, the temperature can be about 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, or 400 degrees Celsius, or at a temperature falling within a range between any of the foregoing, such as from 200 to 400 degrees Celsius, or from 250 to 350 degrees Celsius, or from 275 to 325 degrees Celsius, or from 290 to 310 degrees Celsius.
The reactor can be configured to maintain pressure suitable to keep the reactants from boiling at the temperatures referenced above. In some embodiments, the pressure (or back pressure) can be about 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, or 3000 PSI, or a pressure falling within a range between any of the foregoing.
Contact time can be configured to optimize the efficiency of conversion into reaction products. In some embodiments, the contact time can be at least about 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds, 60 seconds, 2, minutes, 5 minutes, 10 minutes, 15 minutes, 30 minutes, or longer, or an amount of time falling within a range between any of the foregoing.
In various embodiments, high conversion rates or lipid feedstocks and/or branched chain carboxylic acids can be achieved herein. For example, conversion rates to branched chain esters can be about 80, 85, 90, 95, 96, 97, 98, or 99 percent can be achieved, or a percent conversion falling within a range between any of the foregoing can be achieved. In some embodiments, a conversion rate of at least 95.8 percent can be achieved.
Metal oxides used with embodiments of the invention can include metal oxides whose surfaces are dominated by Lewis acid-base chemistry. A Lewis acid is an electron pair acceptor. Metal oxides of the invention can have Lewis acid sites on their surface and can specifically include alumina, zirconia, titania and hafnia. Metal oxides of the invention can also include silica clad with a metal oxide selected from the group consisting of zirconia, alumina, titania, hafnia, zinc oxide, copper oxide, magnesium oxide and iron oxide. In some embodiments, metal oxides can include yttria (yttrium oxide), such as yttria stabilized zirconia. In some embodiments, metal oxides can include magnesium oxide and/or cerium dioxide. Metal oxides of the invention can also include mixtures of metal oxides. Specifically metal oxides of the invention can include mixtures including one or more of zirconia, alumina, titania and hafnia.
Of the various metal oxides that can be used with embodiments of the invention, zirconia, titania and hafnia offer particular advantages because they are very chemically and thermally stable and can withstand very high temperatures and pressures (such as supercritical conditions for various alcohols) as well as extremes in pH. Such catalysts can exhibit a resistance to poisoning over time. In some embodiments, the metal oxide catalyst can include zirconia, titania, and/or hafnia. Zirconia and hafnia are even more thermally stable than titania. In some embodiments, the metal oxide catalyst can include zirconia and/or hafnia.
Some feedstocks may include components, such as lecithin, that can lead to the deposit of residues resulting in clogging and/or obstruction of a transesterification reactor. The significant thermal stability of metal oxides used with embodiments of the invention can be advantageous in this context because the reactor can be cleaned out through the use of an oxygen containing gas or liquid at extremely high temperatures to combust any residue that has been deposited on the metal oxide catalyst, thereby cleaning the reactor and returning it to its original state. Other types of catalysts may not have sufficient thermal stability to perform such a cleaning/regeneration process.
In some embodiments, the metal oxides used with embodiments of the invention can be bare or unmodified. As used herein, the term “unmodified metal oxide” shall refer to a metal oxide that includes substantially only the metal oxide at its surface, and thus does not include significant concentrations of chemical groups such as phosphates or sulfates on its surface. Many conventional catalyst materials include various modifying groups to enhance catalysis. However, as shown in the examples herein, unmodified metal oxides can surprisingly be used to achieve high conversion percentages and relatively small residence times.
However, in other embodiments, metal oxides of the invention can be modified with another compound. For example, the Lewis acid sites on metal oxides of the invention can interact with Lewis basic compounds. Thus, metal oxides of the invention can be modified by adsorbing Lewis basic compounds to the surface of metal oxides of the invention. A Lewis base is an electron pair donor. Lewis basic compounds of the invention can include anions formed from the dissociation of acids such as hydrobromic acid, hydrochloric acid, hydroiodic acid, nitric acid, sulfuric acid, perchloric acid, boric acid, chloric acid, phosphoric acid, pyrophosphoric acid, methanethiol, chromic acid, permanganic acid, phytic acid and ethylenediamine tetramethyl phosphonic acid (EDTPA).
While not intending to be bound by theory, the use of strong acids as a modifying group can be advantageous because they absorb more strongly to the Lewis acid sites on the metal oxide and thus be less likely to leach off into the reaction mixture. As such, the use of phosphoric acid, for example, can be advantageous.
Lewis basic compounds of the invention can also include hydroxide ion as formed from the dissociation of bases such as sodium hydroxide, potassium hydroxide, lithium hydroxide and the like.
Metal oxides of the invention can include metal oxide particles clad with carbon. Carbon clad metal oxide particles can be made using various techniques such as the procedures described in U.S. Pat. Nos. 5,108,597, 5,254,262, 5,346,619, 5,271,833, and 5,182,016, the contents of which are herein incorporated by reference. Carbon cladding on metal oxide particles can render the surface of the particles more hydrophobic.
Metal oxides of the invention can also include polymer coated metal oxides. By way of example, metal oxides of the invention can include a metal oxide coated with polybutadiene (PBD). Polymer coated metal oxide particles can be made using various techniques such as the procedure described in Example 1 of U.S. Pub. Pat. App. No. 2005/0118409, the content of which is herein incorporated by reference. Polymer coatings on metal oxide particles can render the surface of the particles more hydrophobic.
Metal oxide catalysts of the invention can be made in various ways. As one example, a colloidal dispersion of zirconium dioxide can be spray dried to produce aggregated zirconium dioxide particles. Colloidal dispersions of zirconium dioxide are commercially available from Nyacol Nano Technologies, Inc., Ashland, MA. The average diameter of particles produced using a spray drying technique can be varied by changing the spray drying conditions. Examples of spray drying techniques are described in U.S. Pat. Nos. 4,138,336 and 5,108,597, the contents of both are herein incorporated by reference. It will be appreciated that other methods can also be used to create metal oxide particles. One example is an oil emulsion technique as described in Robichaud et al., Technical Note, “An Improved Oil Emulsion Synthesis Method for Large, Porous Zirconia Particles for Packed-or Fluidized-Bed Protein Chromatography,” Sep. Sci. Technol. 32, 2547-59 (1997). A second example is the formation of metal oxide particles by polymer induced colloidal aggregation as described in M. J. Annen, R. Kizhappali, P. W. Carr, and A. McCormick, “Development of Porous Zirconia Spheres by Polymerization-Induced Colloid Aggregation-Effect of Polymerization Rate,” J. Mater. Sci. 29, 6123-30 (1994). A polymer induced colloidal aggregation technique is also described in U.S. Pat. No. 5,540,834, the content of which is herein incorporated by reference.
Metal oxide particles used in embodiments of the invention can be sintered by heating them in a furnace or other heating device at a relatively high temperature. In some embodiments, the particles are sintered at a temperature of 160° C. or greater. In some embodiments, the particles are sintered at a temperature of 400° C. or greater. In some embodiments, the particles are sintered at a temperature of 600° C. or greater. Sintering can be done for various amounts of time depending on the desired effect. Sintering can make the aggregated particles more durable. In some embodiments, the particles are sintered for more than about 30 minutes. In some embodiments, the particles are sintered for more than about 3 hours. However, sintering also reduces the surface area. In some embodiments, the particles are sintered for less than about 1 week.
In some embodiments, particles within a desired size range can be selected for use as a catalyst. For example, particles can be sorted by size such as by air classification, elutriation, settling fractionation, or mechanical screening. In some embodiments, the size of the particles is greater than about 0.2 microns. In some embodiments, the size of the particles is greater than about 0.25 μm. In some embodiments the size range selected is from about 0.2 microns to about 1 mm. In some embodiments the size range selected is from about 1 μm to about 100 μm. In some embodiments the size range selected is from about 5 μm to about 15 μm. In some embodiments the size of the particles is about 80 μm. In some embodiments the size of the particles is about 25-35 μm. In some embodiments the size of the particles is about 5 μm.
In some embodiments, metal oxide particles used with embodiments of the invention are porous. By way of example, in some embodiments the metal oxide particles can have an average pore size of about 30 angstroms to about 2000 angstroms. However, in other embodiments, metal oxide particles used are non-porous.
The anion of an acid can be adhered to a particle by refluxing particles in an acid solution. By way of example, the particles can be refluxed in a solution of sulfuric acid. Alternatively, the anion formed from dissociation of a base, such as the hydroxide ion formed from dissociation of sodium hydroxide, can be adhered to a particle by refluxing particles in a base solution. By way of example, the particles can be refluxed in a solution of sodium hydroxide. The base or acid modification can also be achieved under exposure to the acid or base in either batch or continuous flow conditions when disposed in a reactor housing at elevated temperature and pressure to speed up the adsorption/modification process. In some embodiments, fluoride ion, such as formed by the dissociation of sodium fluoride, can be adhered to the particles.
Metal oxide particles used in embodiments of the invention can be packed into a housing, such as a column. The metal oxide particles disposed in a housing can form a fixed bed reactor. Disposing the metal oxide particles in a housing can offer the advantage of facilitating continuous flow processes. Many different techniques may be used for packing the metal oxide particles into a housing. The specific technique used may depend on factors such as the average particle size, the type of housing used, etc. Generally speaking, particles with an average size of about 1-20 microns can be packed under pressure and particles with an average size larger than 20 microns can be packed by dry-packing/tapping methods or by low pressure slurry packing. In some embodiments, the metal oxide particles of the invention can be impregnated into a membrane, such as a PTFE membrane.
In some embodiments, the reactants can include a lipid feedstock. Exemplary lipid feedstocks herein can include safflower oil, tall oil fatty acid, tung oil, linolenic acid, pennycress oil, coconut oil, castor oil, and flaxseed oil. Other lipid feedstocks herein can include, but are not limited to used cooking oil, algae oil, camelina oil, jatropha oil, and linseed oil.
In various embodiments herein, branched chain carboxylic acids can be used as reactants herein (in addition to or in place of straight chain carboxylic acids). Branched chain carboxylic acids herein can include those with a main chain from C3 to C20 in length along with at least one side chain from C1 to C10 in length. In some embodiments, the main chain length can be C3 to C10 in length and the side chain can be methyl, ethyl, propyl, or butyl.
In some embodiments, branched chain carboxylic acids herein can have the formula of structure (I) below:
wherein n is 0 to 10, R1 is linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne, and R2 is linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne.
Specific branched chain carboxylic acids herein can include, but are not limited to, isovaleric acid, isobutyric acid, 2-methyl butyric acid, and the like. Other branched chain carboxylic acids can include pristanic acid, phytanic acid, 13-methyltetradecanoic acid, 12-methyltetradecanoic acid, 14-methylpentadecanoic acid, 15-methylhexadecanoic acid, 14-methylhexadecanoic acid, and the like. Other specific branched chain carboxylic acids can include, but are not limited to, 2-ethylhexanoic acid, 2-methylhexanoic acid, 5-methylhexanoic acid, isotridecanoic acid.
Branched chain C8 carboxylic acids herein (also known as branched chain octanoic acids) include, but are not limited to, 2-methylheptanoic acid, 3-methylheptanoic acid, 4-methylheptanoic acid, 2,2-dimethylhexanoic acid, 2,3-dimethylhexanoic acid, 2,4-dimethylhexanoic acid, 3,3-dimethylhexanoic acid, 3,4-dimethylhexanoic acid, 2,2,3-trimethylpentanoic acid, 2,2,4-trimethylpentanoic acid, 2,3,3-trimethylpentanoic acid, 2,3,4-trimethylpentanoic acid, 3,3,4-trimethylpentanoic acid, 2,2,3,3-tetramethylbutanoic acid, 2,2,3,4-tetramethylbutanoic acid, 2,2,4,4-tetramethylbutanoic acid, 2,3,3,4-tetramethylbutanoic acid, 2,2,3,3,5-pentamethylpropanoic acid, and/or combinations thereof.
In some embodiments, carboxylic acids herein can include a single carboxylic acid. In other embodiments, carboxylic acids herein can include a blend of carboxylic acids. For example, a blend of carboxylic acids herein can include 2, 3, 4, 5, 6, 7, 8, or more different carboxylic acids. In some embodiments, at least two branched chain carboxylic acids in a blend have a different chain length from one another. For example, in some embodiments, the blend of carboxylic acids can include at least one C4 or less carboxylic acid in combination with at least one C5 or more carboxylic acid, such as in ratios of 1:99, 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, 95:5, or 99:1 by weight (C4 or less to C5 or more).
In some embodiments, blends of carboxylic acids herein can include a blend of at least one branched chain carboxylic acid with at least one non-branched chain carboxylic acid, such as in ratios of 1:99, 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, 95:5, or 99:1 by weight (C4 or less to C5 or more).
In various embodiments herein, alcohols can include one or more branched chain alcohols. For example, alcohols herein can include one or more branched chain primary alcohols and/or one or more branched secondary alcohols. In some embodiments, branched alcohols herein can include asymmetrically branched alcohols.
In some embodiments, alcohols herein can include at least one branched chain alcohol comprising a C4 to C20 alcohol. In some embodiments, alcohols herein can include at least one branched chain alcohol comprising a C5 to C20 alcohol. In some embodiments, alcohols herein can include at least one branched chain alcohol comprising a C6 to C20 alcohol.
In some embodiments, alcohols herein can have the formula of structure (II) below:
wherein n is 0 to 10, R1 is linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne, and R2 is linear or branched, aliphatic or aromatic, saturated, monounsaturated, or polyunsaturated, C1 to C20 alkyl, alkene, or alkyne.
In some embodiments, the at least one branched chain alcohol comprising at least one selected from the group consisting of isoheptanol, isooctanol, isononanol, and isodecanol. In some embodiments, the at least one branched chain alcohol comprising 2-ethyl octanol. Other specific branched chain alcohols herein can include, but are not limited to, 2-ethyl hexanol, 2-ethyl octanol, 2,4-Dimethyl-1-octanol, 3,5-dimethyl-1-octanol. Alkenyl alcohols herein can include, but are not limited to, cis-3,7-Dimethyl-2,6-octadien-1-ol, cis-5-octen-1-ol, and cis-3-hexenol.
Alcohols herein can include aromatic alcohols. In some embodiments, alcohols herein can include C6 to C20 alcohols including at least one aromatic group. By way of example, aromatic alcohols herein can specifically include benzyl alcohol. Other specific aromatic alcohols herein can include, but are not limited to, phenylethyl alcohol, 3-phenyl-1-propanol, 2-ethyl-3-phenylpropanol, 1-naphthylpropanol.
In some embodiments, the alcohol can include one or more of isooctanol sold under the tradename EXXAL-8 (commercially available from ExxonMobil), isononanol sold under the tradename EXXAL-9 (commercially available from ExxonMobil), isodecanol sold under the tradename EXXAL-10 (commercially available from ExxonMobil), and the like.
In some embodiments, alcohols herein can include a single alcohol. In other embodiments, alcohols herein can include a blend of alcohols. For example, a blend of alcohols herein can include 2, 3, 4, 5, 6, 7, 8, or more different alcohols. In some embodiments, at least two branched chain alcohols in a blend have a different chain length from one another. For example, in some embodiments, the blend of alcohols can include at least one C4 or less alcohol in combination with at least one C5 or more alcohol, such as in ratios of 1:99, 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, 95:5, or 99:1 by weight (C4 or less to C5 or more). In some embodiments, the blend of alcohols can include at least one of methanol, ethanol, propanol, isopropanol, butanol, isobutanol, along with at least one C5 or more alcohol.
In some embodiments, blends of alcohols herein can include a blend of at least one branched chain alcohol with at least one non-branched chain alcohol. While not intending to be bound by theory, branched chain alcohols can be useful for various aspects including lowering freezing points of reaction products and shorter non-branched chain alcohols can be useful for increasing volatility as measured by boiling point. In some embodiments, a branched chain alcohol as described herein can be used in combination with, for example, a C1 to C8 non-branched alcohol, such as in ratios of 1:99, 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, 95:5, or 99:1 by weight (branched chain alcohol(s) to non-branched chain alcohols). In some embodiments, a branched chain alcohol as described herein can be used with at least one of methanol, ethanol, propanol, and/or butanol, or the like.
Aspects may be better understood with reference to the following examples. These examples are intended to be representative of specific embodiments, but are not intended as limiting the overall scope of embodiments herein.
A fixed-bed, titania catalytic reactor was set up including components consistent with that described with respect to
Various lipid feedstock or branched chain carboxylic acid feedstocks were reacted with various branched alcohols (as shown in Table 1) and the reaction products were evaluated for various characteristics including freezing point and acid number (as shown in
This example shows that branched chain alcohols can be reacted with various lipid feedstocks to produce reaction products including branched chain esters with remarkably low freezing points suitable for use as and in sustainable aviation fuels.
It should be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing “a compound” includes a mixture of two or more compounds. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
It should also be noted that, as used in this specification and the appended claims, the phrase “configured” describes a system, apparatus, or other structure that is constructed or configured to perform a particular task or adopt a particular configuration. The phrase “configured” can be used interchangeably with other similar phrases such as arranged and configured, constructed and arranged, constructed, manufactured and arranged, and the like.
All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated by reference.
As used herein, the recitation of numerical ranges by endpoints shall include all numbers subsumed within that range (e.g., 2 to 8 includes 2.1, 2.8, 5.3, 7, etc.).
The headings used herein are provided for consistency with suggestions under 37 CFR 1.77 or otherwise to provide organizational cues. These headings shall not be viewed to limit or characterize the invention(s) set out in any claims that may issue from this disclosure. As an example, although the headings refer to a “Field,” such claims should not be limited by the language chosen under this heading to describe the so-called technical field. Further, a description of a technology in the “Background” is not an admission that technology is prior art to any invention(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the invention(s) set forth in issued claims.
The embodiments described herein are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art can appreciate and understand the principles and practices. As such, aspects have been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope herein.
This application claims the benefit of U.S. Provisional Application No. 63/608,607, filed Dec. 11, 2023, the content of which is herein incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63608607 | Dec 2023 | US |
