Systems and methods for ketonic decarboxylation of carboxylic acids

Abstract

A method for producing ketones through ketonic decarboxylation using selected ketonization catalysts where water inhibition is diminished by removing the water of reaction from the reaction zone by running the process in stages and performing interstage water removal using molecular sieves or water-permeable membranes, or by loading a water-permeable membrane system with suitable ketonization catalyst, or by using a water-permeable membrane system with catalytic activity and thus performing water removal in situ.

Description

130647-0244 SYSTEMS AND METHODS FOR KETONIC DECARBOXYLATION OF CARBOXYLIC ACIDSCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No.63 / 753,869, filed February 4, 2025, the entire disclosure of which is incorporated by reference herein in its entirety and for all purposes.TECHNOLOGY

[0002] Provided herein are methods and systems for converting carboxylic acids, mainly medium-chain fatty acids, but also their corresponding esters and salts, into ketones using ketonic decarboxylation with catalysts for use as chemical solvents, base oils, or intermediates for hydrocarbon fuels production. Embodiments of the disclosure pertain to minimizing water inhibition and ensuring a high degree of conversion of the carboxylic acids, esters or salts into their corresponding ketones.BACKGROUND

[0003] Mixed-culture fermentation from renewable biomass resources can be one of the most economically competitive methods to convert biomass materials to renewable chemicals and fuels. The microorganisms generally produce a mixture of organic carboxylic acids, which are volatile fatty acids (VFAs). These VFAs are generally short-chain fatty acids (SCFAs) and medium-chain fatty acids (MCFAs) typically ranging from acetic acid (C2) to octanoic acid (C8) (although small amounts of C9 and even CIO and Cl 1 fatty acids have also been observed). Ketones can be produced from carboxylic acids and more specifically VFAs, or their salts and esters, using a process known as ketonic decarboxylation, where two VFA molecules in the acid, salt or ester form, which can be the same or different, form the ketone while removing a carbon dioxide (CO2) molecule.

[0004] Depending on whether the ketonic decarboxylation, also referred herein as ketonization, occurs from the salts or from the acids, two different types of ketonization may be carried out: bulk ketonization or surface catalytic ketonization. The mechanisms for each type are different, in that in the former, the acids are in the salt form and thermal decomposition of the salts occurs forming the ketone, which vaporizes, while leaving behind the carbonate salt of the original cation. On the other hand, in the latter case, surface catalytic ketonization typically occurs when acids are fed to, for example, amphoteric metal oxides, where the reaction occurs on the surface of these metal oxides, which convert the acids to ketones, CO2 and water. VFA salts of, for example, but not limited to, beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd) undergo bulk ketonization when heated to temperatures above 300°C. On the other hand, the acid form of the VFAs undergo catalytic surface ketonization at temperatures above 200°C in contact with oxides of a high lattice energy such as,130647-0244 but not limited to, titanium oxide (titania, TiO?). zirconium oxide (zirconia, ZrCh), cerium oxide (ceria, CeCh) and many other metal oxides, with those of amphoteric nature having a high activity.

[0005] However, water entering with the feed and / or formed during ketonization has been shown to have a high inhibitory effect with certain catalysts, to the point that a single reactor without water removal, would become prohibitively expensive from a capital standpoint if pushing for high conversions. To avoid high capital costs during high conversion efforts, performing the reaction in multiple stages with interstage water removal has been suggested to improve the reaction economics by decreasing water inhibition, thus decreasing the total length / size of the required reactor beds. When VFAs are involved in the ketonization reaction, interstage water separation is difficult because solubility and boiling point differences between the water and VFAs are less pronounced. In addition, VFAs and the resulting ketones are in the vapor phase at typical ketonization reaction temperature and pressure conditions (e.g., but not limited to, >300°C, <200 psig). The water separation methods previously available require first condensing the ketones and unreacted acids after every stage to allow water to either phase separate or to remain as vapor and leave with the CO2 and the sweep gas, followed by revaporization of the unreacted acids and ketones prior to being fed to the next ketonization step. Such condensation followed by re-vaporization after every stage represents a large energy inefficiency. Thus there is a need for methods of facilitating high yield ketonization reactions of fatty acids that avoid high energy inefficiencies.SUMMARY

[0006] In a first aspect, which can be combined with any other aspect or embodiments, provided herein is a method for producing ketones including contacting, in a first reactor, a feedstock including fatty acids with a first ketonization catalyst to convert at least a portion of the fatty acids of the feedstock into ketones and produce a first product comprising ketones, unreacted fatty acids, and water; contacting the first product with a molecular sieve to absorb the water to produce a water-lean first product; and contacting, in a second reactor, the water-lean first product with a second ketonization catalyst to convert at least a portion of the unreacted fatty acids in the water-lean first product into ketones and produce a second product comprising ketones, unreacted fatty acids, and water.

[0007] In some embodiments, the method for making ketones mentioned above utilizes ketonization catalysts that are metal oxides, amphoteric metal oxides, or other oxides. In some embodiments, in the method for making ketones mentioned above, the fatty acids include C4-C9 fatty acids or the ketones include C7-C17 ketones.

[0008] In some embodiments, the method includes additional steps such as contacting the second product with a molecular sieve to absorb water to produce a water-lean second product; and contacting, in a third reactor, the water-lean second product with a third ketonization catalyst to convert130647-0244 at least a portion of the unreacted fatty acid in the water-lean second product to ketones and water and to produce a third product comprising ketones, unreacted fatty acids, and water.

[0009] In some embodiments, the method includes iterative repetition of steps to achieve a desired yield of ketones. In some embodiments, the method includes, starting with the second product, iteratively repeating steps including: contacting the product with a molecular sieve to produce a waterlean product; and contacting, in a reactor, the water-lean product with a ketonization catalyst to convert at least a portion of unreacted fatty acids in the water-lean product to ketones and to produce a subsequent product, until the yield of ketones in a product is greater than 98% of the theoretical maximum ketone yield; and collecting the product having a yield of ketones greater than 98% of the theoretical maximum ketone yield.

[0010] In some embodiments, in the methods mentioned above, the contacting the fatty acids with the first ketonization catalyst and contacting the first products with a molecular sieve occurs in the same reactor; or wherein contacting the first products with a molecular sieve and contacting the fatty acids with the second ketonization catalyst occurs in the same reactor.

[0011] In some embodiments, the ketonization is performed at temperatures ranging from about 200 °C to about 500 °C, and preferably from about 300 °C to about 450 °C.

[0012] In another aspect, which can be combined with any other aspect or embodiments, provided herein is a method for producing ketones, method for producing ketones, the method including: in a first reactor, contacting a feedstock comprising fatty acids with a first ketonization catalyst to produce a first product comprising ketones, unreacted fatty acids, and water; providing the first product to a water-permeable membrane system to remove at least a portion of the water in the first product; and in a second reactor, contacting the water-lean first product with a second ketonization catalyst to convert at least a portion of the fatty acids in the water-lean first product to ketones and water to form a second product comprising ketones, unreacted fatty acids, and water.

[0013] In some embodiments, in the method mentioned above the first and / or second ketonization catalysts are metal oxides or amphoteric metal oxides. In some embodiments, the fatty acids include C4-C9 fatty acids or the ketones include C7-C17 ketones.

[0014] In some embodiments, the method includes further step including: providing the second product to a water-permeable membrane system to remove at least a portion of the water in the second product; and in a third reactor, contacting the water-lean second product with a third ketonization catalyst to convert at least a portion of the fatty acids in the water-lean second product to ketones and water and to form a third product comprising ketones, unreacted fatty acids, and water.130647-0244

[0015] In some embodiments, the method includes iterative repetition of steps to achieve a product having a desired yield of ketones. In some embodiments, the method includes, starting with the second product, iteratively repeating steps including: contacting the product with a water-permeable membrane system to produce a water-lean product; and contacting, in a reactor, the water-lean product with a ketonization catalyst to convert at least a portion of unreacted fatty acids in the water-lean product to ketones and to produce a subsequent product, until the yield of ketones in a product is greater than 98% of the theoretical maximum ketone yield; and collecting the product having a yield of ketones greater than 98% of the theoretical maximum ketone yield.

[0016] In some of these embodiments, the contacting the fatty acids with the first ketonization catalyst and contacting the first products with a water-permeable membrane system occurs in the same reactor; or the contacting the first products with a water-permeable membrane system and contacting the fatty acids with the second ketonization catalyst occurs in the same reactor.

[0017] In some embodiments, the ketonization is performed at temperatures ranging from about 200 °C to about 500 °C, and preferably from about 300 °C to about 450 °C.

[0018] In yet another aspect, which can be combined with any other aspect or embodiments, provided herein is a method for producing ketones, the method including: contacting fatty acids with a ketonization catalyst located inside or outside of water-permeable membranes to form ketones, water, and CO2 such that the water-permeable membranes separate at least a portion of the water from the ketones as the water is formed. In an embodiment, the ketonization catalyst is metal oxides or amphoteric metal oxide, or other oxides. In some embodiments, the fatty acids include C4-C9 fatty acids or the ketones include C7-C17 ketones.

[0019] In some embodiments, the ketonization is performed at temperatures ranging from about 200 °C to about 500 °C, and preferably from about 300 °C to about 450 °C.

[0020] In another aspect, which can be combined with any other aspect or embodiments, a method for producing ketones includes contacting fatty acids with a water-permeable membrane, the water-permeable member provides ketonization catalytic activity at at least one of an inside surface and an outside surface of the water-permeable membrane, wherein contacting the fatty acids with the water-permeable membrane produces ketones, water, and CO2, and wherein at least a portion of the water is separated from the ketones by the water-permeable membrane as the water is formed. In an embodiment, the ketonization catalytic activity of the water-permeable membranes is due to or provided by the presence of amphoteric metal oxides, metal oxides, or other oxides. In another aspect of the embodiment above, the fatty acids include C4-C9 fatty acids or the ketones include C7-C17 ketones.130647-0244

[0021] In some embodiments, the ketonization is performed at temperatures ranging from about 200 °C to about 500 °C, and preferably from about 300 °C to about 450 °C.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. l is a schematic of a process for the extraction of fatty acids using carbon dioxide and conversion to hydrocarbons by ketonization and hydrodeoxygenation according to an embodiment.

[0023] FIG. 2 is a schematic of a ketonization process occurring in stages with interstage water removal using condensation and phase separation, according to an embodiment.

[0024] FIG. 3 is a schematic of a ketonization process occurring in stages with interstage water removal using flash tanks or distillation towers, according to an embodiment.

[0025] FIG. 4 is a schematic of a ketonization process occurring in stages with interstage water removal using high-temperature molecular sieves, according to an embodiment.

[0026] FIG. 5 is a schematic of a ketonization process occurring in stages with interstage water removal using high-temperature molecular sieves, with the high-temperature molecular sieves in the same reactor or piece of equipment with the ketonization catalyst, according to an embodiment.

[0027] FIG. 6 is a schematic of a ketonization process occurring in stages with interstage water removal using water-permeable membranes, according to an embodiment.

[0028] FIG. 7 is a schematic of a ketonization process occurring in stages with interstage water removal using water-permeable membranes, with the water-permeable membranes in the same reactor or piece of equipment with the ketonization catalyst, according to an embodiment.

[0029] FIG. 8 is a schematic showing the details of the ketonization reaction occurring on ketonization catalyst pellets, which are located inside or outside of tubular water-permeable membrane, according to an embodiment.

[0030] FIG. 9 is a schematic showing the details of the ketonization reaction occurring on the inside or outside surface of a dual catalytic and water-permeable membrane tubular unit, according to an embodiment.

[0031] FIG. 10 is a schematic of a ketonization process where the ketonization reaction occurs in the inside or outside of either a tubular water-permeable membrane or a dual catalytic and water-permeable tubular unit, according to an embodiment.130647-0244

[0032] FIGS. 11A and 1 IB are flowcharts of a process for the extraction of fatty acids using carbon dioxide and conversion to hydrocarbons by ketonization having interstage or simultaneous water removal.DETAILED DESCRIPTION

[0033] Herein disclosed are novel apparatuses, systems, and methods that pertain to converting volatile fatty acids (VFAs) to ketones with interstage and / or simultaneous water removal. In some embodiments, the VFAs are obtained at least in part from a fermentation. According to an embodiment, the VFAs are obtained as salts contained in an aqueous solution. In certain embodiments, high-pressure gaseous, subcritical liquid or supercritical CO2 is used to recover VFAs from aqueous solutions containing VFA salts and the extracted VFAs are provided to a ketonization process. According to an embodiment, the extracted VFAs are separated into medium-chain fatty acids (MCFAs) and short chain fatty acids (SCFAs), and the MCFAs are sent to the ketonization process. In some embodiments, the MCFAs are further sent to an evaporator or a distillation tower to remove impurities before being directed to the ketonization process.

[0034] The catalytic ketonization reaction can be efficient in achieving near theoretical yields characterized by high conversions and selectivities but suffers from water inhibition with certain catalysts, which can make the ketonization process cost prohibitive from a capital standpoint due to the large reaction vessels required. Running the reaction in stages to remove the water in between such stages can improve the efficiency of the reaction and decreasing the size of the reactors. Water present in the MCFAs may be preemptively removed prior to ketonization, as described in some embodiments herein. However, water is also produced during the ketonization reaction; therefore, removal of water from the ketonization reaction zone via interstage water removal between ketonization stages or via simultaneous removal of water with the ketonization reaction is also provided in various embodiments herein.

[0035] According to various embodiments, interstage removal of water is done using water separation techniques, high-temperature molecular sieves, which absorb water, or using high-temperature membranes, which are permeable to water, or performing the ketonization in membrane reactors loaded with catalyst pellets while tubular high-temperature water-permeable membranes traverse the reactor to allow water removal. Other embodiments allow for catalytic activity to exist on surface of the membrane, thus the membranes carry out a double-duty action, where they serve as the catalyst while also removing the water from the reaction zone.

[0036] Various embodiments are described herein. It should be noted that the specific embodiments are not intended as an exhaustive description or as a limitation to the broader aspects discussed herein. One aspect described in conjunction with a particular embodiment is not necessarily130647-0244 limited to that embodiment and can be practiced with any other embodiment(s). The present disclosure should in no way be limited to the example implementations, drawings, and techniques described or illustrated herein. Additionally, the drawings are not necessarily drawn to scale and may not illustrate obvious pieces of equipment such as certain flow controllers, pumps, compressors, valves, piping, larger number of stages (as in distillation or extraction), and various instrumentation, controllers, and sensors. One of ordinary skill in the art would readily understand the difference between a general process flow diagram (PFD) or a block flow diagram (BFD) as compared to the intricate and detailed aspects involved with an actual process. The PFD(s) and BFD(s) are described in general detail for brevity, though a person of ordinary skill in the art would understand that supporting components and structures may be required. It should be understood that, although example implementations of embodiments of the disclosure are described herein, the systems, methods, and processes of this disclosure may be implemented using any number of techniques, whether currently known or not.

[0037] As utilized herein with respect to numerical ranges, the terms “approximately,” “about,” “primarily,” “substantially,” “mostly,” and similar terms will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the terms that are not clear to persons of ordinary skill in the art, given the context in which it is used, the terms will be plus or minus 10% of the disclosed values. When “approximately,” “about,” “primarily,” “substantially,” “mostly,” and similar terms are applied to a feature (e.g., to describe its shape, size, orientation, direction, composition, etc.), these terms are meant to cover minor variations in structure or composition that may result from, for example, the manufacturing or assembly process and are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims.

[0038] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.130647-0244

[0039] Carboxylic acids are classified herein according to the number of carbon atoms associated with the acid. A subset of carboxylic acids, referred to herein as volatile fatty acids (VFAs), includes fatty acids that range from one-carbon chain length to twelve-carbon chain length. These VFAs are more specifically formic acid (Cl), acetic acid (C2), propionic acid (C3), butyric acid (C4), valeric acid (C5), caproic acid (C6), heptanoic acid (C7), caprylic acid (C8), nonanoic acid (C9), decanoic acid (CIO), undecanoic acid (Cl 1) and dodecanoic (Cl 2) acids. Branched VFAs, e.g., isobutyric acid (iC4), 2-methylbutyric and 3 -methylbutyric (isovaleric acid - iC5) acids, and 2-methylpentanoic, 3-methylpentanoic and 4-methylpentanoic (isocaproic acid - iC6) acids, are also contemplated. As used herein, medium-chain fatty acids (MCFAs) are individual or mixed fatty acids with carbon numbers ranging from C5-C12 or mixtures thereof. In the processes described, MCFAs are predominantly, but not necessarily limited to, C5-C9 fatty acids. It should be understood that small quantities of CIO, Cl 1, and C12 fatty acids may also be present. As matter of fact, C9 is also produced in small quantities in fermentation, so C9 might also be found in small quantities. The MCFAs might be straight-chain or branched, for example, 2-methylbutyric, iso-valeric (3 -methylbutyric) and 2-methylpentanoic, 3-methylpentanoic and iso-caproic (4-methylpentanoic) acids. On the other hand, short-chain fatty acids (SCFAs) are individual or mixtures of fatty acids with carbon numbers ranging from C2-C4, straightchain or branched, for example, iso-butyric acid, or mixtures thereof. It should be understood that small quantities of the shortest VFA, formic acid (Cl), and other acids such as lactic and succinic acid, may also be present.

[0040] In some embodiments, VFAs are produced from fermentation. The fermentation includes the anerobic digestion or acidogenic fermentation and breakdown of a feedstock by a microbiome comprising microorganisms. The feedstock for the fermentation is at least partially biodegradable. The feedstock may be synthetic in nature, or may be derived from other processes such as hydrocarbon refining, but is more preferably derived from natural sources. In embodiments where the feedstock is naturally sourced, the feedstock may include materials such as, though not limited to: biomass (including vegetation such as grasses, leaves, and wood), agricultural waste or byproducts, lumber industry waste or byproducts, food industry waste or byproducts, dairy industry waste or byproducts, municipal solid or liquid wastes, including post-consumer food waste. In some embodiments, the byproduct or waste material includes, but is not limited to, by-products or wastes from the food and agricultural industry, such as, dairy sources (including milk, milk solids, whey, whey powder, acid whey, whey permeate, lactose, or yogurt), sugars (including those derived from com, beet, palm, or sugar cane), sugar sources (including maple syrup, molasses, caramel, or soda syrup), starch and fiber or lignocellulosic sources (including those from pea, oat, barley, com, potato, rice, wheat, milo, malt, tapioca, pasta, or bread), fmit- and vegetable-based sources (including juices, pastes, or peels), vegetable -based oils (including canola oil, com oil, peanut oil, soybean oil, palm oil, rapeseed oil, or their derived glycerol and fatty acids), vegetable-based proteins (including soy protein, pea protein, wheat130647-0244 protein, com protein, or their concentrates and isolates), other protein and nutrient sources (whey, soybean meal, com steep liquor, yeast extract).

[0041] In some embodiments, the microorganisms in the fermentation microbiome may be naturally sourced. In other embodiments, the microorganisms may be commercially-sourced or sourced from a laboratory and may include genetic modifications directed toward increased efficiency and production of target fermentation products and other characteristics. The microorganisms are selected to produce fatty acids and fatty acid salts, preferably salts of short- and medium-chain fatty acids (SCFA and MCFA salts). For example, in some embodiments, the fermentation produces a product stream including salts of volatile fatty acids ranging from 2 to 9 carbons, for example, but not limited to, salts of acetic (C2), propionic (C3), iso-butyric (iC4), butyric (C4), iso-valeric (iC5), valeric (C5), iso-caproic (i-C6), caproic (C6), heptanoic (C7), caprylic (C8) and nonanoic (C9) acids. The salts of the shortest VFA, formic acid (Cl), and fatty acid salts having longer carbon chains, such as C10-C12, may also be present. The microorganisms of the fermentation microbiome may also be selected for their ability to elongate fatty acid carbon chains, for example, through the reverse [3-oxidation pathway.

[0042] Described herein are methods and systems including ketonization reactions or equipment suitable for ketonization reactions. Such reactions may be carried out at any suitable conditions, but are typically carried out at temperatures greater than 200°C, and preferably greater than 300°C, but lower than 500°C, and preferably lower than 450°C. Various portions of the methods and systems described herein may be performed or operate at pressures greater than atmospheric or lower than atmospheric. The ketonization methods and systems may be performed or operated at a pressure ranging from atmospheric to about 100 psig, or from about atmospheric to about 50 psig, or from about atmospheric to about 30 psig. The ketonization methods and systems may be performed or operated at pressure ranging from atmospheric (760 mm Hg absolute) to about -14 psig (about 36 mm Hg absolute), or from about atmospheric to about -7 psig (about 398 mm Hg absolute) , or from atmospheric to about -3 psig (about 605 mm Hg).

[0043] Embodiments are often described in a stepwise manner (e.g., describing process flow step-by-step), but the disclosure should in no manner be so limited. Although flow streams or products are often described as ‘sent’ from one location to another, the disclosure encompasses use of any and all aspects of fluid / product handling and transport (e.g., pumps, piping, vessels, etc.). Finally, although any process stream may be shown as directed to a particular destination (e.g., unit operation, vessel, system, etc.), the destination and handling of the process stream are not limited to such a depiction and it should be understood that intermediate handling or process steps may be carried out even though not explicitly mentioned or illustrated. Thus, a process stream may be sent to a flash column, a flash tank, a distillation column, combinations thereof, etc.130647-0244

[0044] It is also noted, and as would be apparent to one of skill in the art, process streams described herein need not be clean cut or pure. When referring to particular product streams herein, it should be understood that, although the primary product(s) may be described, some amounts of other products may exist in the product stream. Thus, there may be quantities of other compounds in such streams and / or other impurities. For example, a stream referred to as containing MCFAs, or even purified MCFAs, the bulk of such MCFA stream may comprise valeric, hexanoic, heptanoic, octanoic and nonanoic acid, individually or in combinations thereof, but it the stream may also contain some amount of water and / or small quantities of lighter fatty acids (C1-C4), heavier acids (C10-C11), CO2, salt cations, alcohols, esters, and / or impurities. Similarly, if referred to SCFAs, commonly C2-C4 are used, the bulk of the C2-C4 acids stream might comprise, acetic, propionic and butyric acid, individually or in combination thereof, but it may also contain, in addition to some water, small quantities of the heavier fatty acids (C5-C9), but also formic acid (Cl), lactic acid, succinic acid, CO2, salt cations, and / or impurities. Similarly, for example, if referred to C9-C17 ketones, the bulk of the stream might comprise of C9-C17 ketones, or C9-C16 ketones, or C9-C15 ketones, or C9-C14 ketones, or C9-C13 ketones, or C9-C12 ketones, or C9-C11 ketones individually or combinations thereof, but it may also contain, in addition to some water, small quantities of lighter ketones (C3-C8, individually or combinations thereof), unreacted C4-C9 acids, hydrocarbons, and other impurities such as, but not limited to, sulfur, nitrogen impurities.

[0045] VFAs may be produced from the fermentation of renewable organic feedstocks, with the majority of the VFAs being C2-C8 fatty acids. Small quantities of one-carbon chain length (Cl), nine-carbon chain length (C9), ten-carbon chain length (CIO), and eleven-carbon chain length (Cl 1) fatty acids may also be produced by the fermentation process. In addition, other metabolites may also be produced such as, but not limited to, lactic acid, succinic acid, ethanol, propanol, 1,2-propane diol, and 1,3 -propane diol. These above-mentioned VFAs may be in their salt form during the fermentation process due to the addition of buffering agents to control pH and avoid low pH levels in the fermentation, as low pH levels can be inhibitory to the fermentation microorganisms. These fatty acids may be recovered using an acid recoveryprocess, which may include separate or simultaneous acidification and extraction or distillation steps. The use of carbon dioxide (CO2) as an acidification agent is of great interest because it avoids the use of mineral acids, which can produce unwanted byproducts and may be difficult to regenerate for reuse. Carbon dioxide can also be used advantageously as an extractant for the acidified fatty acids. This may be desired if it is preferred to extract primarily the medium -chain fatty acids (MCFAs), with any short-chain fatty acids (SCFAs) remaining mostly unextracted in the raffinate of the extraction process. The raffinate containing the SCFAs can be recycled to fermentation where they can biologically elongate into MCFAs via reverse |3-oxidation or other biological pathways.

[0046] The carbon length of the fatty acids that are selectively and advantageously extracted by CO2 are ideal when the final intended product are hydrocarbons for producing drop-in hydrocarbon fuels130647-0244 in the range of the carbon chain length of gasoline (C5 to CIO), jet fuel (C8 to Cl 6), and diesel (>C14), but more preferably jet fuel (C8 to C16).

[0047] The process shown in FIG. 1 illustrates a feed solution 100 containing VFAs ranging mostly from C2-C9 acids, which may come from fermentation, being fed to an extraction system 101 where CO2 102 in gaseous, liquid, or supercritical state is used to selectively extract C5-C9 VFAs 109, also known as medium -chain fatty acids (MCFAs). Only a small amount of C2-C4 VFAs, also known as short-chain fatty acids (SCFAs), are extracted, with most remaining unextracted in the raffinate 103 to be purged 104 or recycled 107 to fermentation. The CO2 106 entrained in the raffinate can be separated in a separation vessel 105, such as a raffinate heater, flash tank, steam stripper, vacuum flash drum, degassing vessel, packed stripping column, or other separation vessel 105, and can be fed back into the system for reuse in the extraction process. The bulk of the CO2 111 is efficiently recovered from the C5-C9 VFA stream 109 by, for example, distillation 110 at high pressure and then recycled 111 to the extraction system 101. The CO2 111 is sent to the CO2 recycle system where it is added to a high-pressure CO2 recycle stream 112. One or more compressors 122 can be used to pressurize low-pressure recycle streams 106 128 and makeup CO2121, and a compressor or pump 113 (depending on the phase of CO2 used in the extraction) is used to provide the CO2 102 the extraction system 101.

[0048] Once the CO2 111 has been recovered at high pressure, the resulting mixture of water, SCFAs, and MCFAs 115 may be depressurized in a depressurization device 140. Further, any C2-C4 VFAs (SCFAs) and / or water that are extracted may optionally be separated 117 from the C5-C9 VFAs (MCFAs) 118 in an acid separation unit 116 (such as an evaporator or distillation column) and recovered or sent back to fermentation for biological elongation. The resulting C5-C9 VFAs (MCFAs) 118 may undergo further purification in an acid purification unit / system 119 (such as, but not limited to, an evaporator or distillation system) to remove heavy impurities 120 (e.g., longer chain fatty acid salts).

[0049] The purified MCFAs 123 are then sent to a ketonization system 124, where surface catalytic ketonic decarboxylation, also known as ketonization, may occur in the presence of the proper catalyst (e.g., metal oxides, discussed further below) to form ketones (primarily ranging from C9-C17 in length), water, and CO2. The ketonization system 124 may include a single reactor or may include several pieces of equipment as described in other embodiments in this disclosure. The purified MCFA stream 123 may optionally be heated, and is then fed into the ketonization system 124. A sweep gas may also be fed into the ketonization system or a vacuum may be pulled, which aids in moving the reactants and products along within the equipment and is expected to reduce water inhibition, although a high sweep gas flow can also be expensive. Among the different types of sweep gases that may be employed, any suitable inert gas such as, but not limited to, nitrogen, helium, and argon may be used. The use of CO2 as the sweep gas is contemplated, which has advantages in that CO2 is produced by the ketonization reaction and the fermentation and can be directly recycled for use elsewhere in the system, thus avoiding having130647-0244 to separate the CO2 produced in the ketonization from a different inert gas. CO2, unlike water, has not been observed to cause ketonization reaction inhibition.

[0050] In the ketonization system 124, the extracted acids are converted to ketones, CO2, and water according to the following reaction scheme:In this reaction scheme, Ri and R2 may be straight or, in minor quantity, branched carbon chains ranging from 1 to 7 (or 8) carbons in length. As a result, the ketones may include from C3 (acetone), such as when two acetic acids react, to C17 (heptadecanone), when two nonanoic acids react. However, because of the selective extraction of C5-C9 MCFAs, the ketones will be mostly C9-C17 ketones. In general, the formula to find the resulting carbon chain length for the resulting ketones is as follows:ketoneWhere m and n are the carbon numbers of the reacting VFAs and m and n can be equal.

[0051] The ketonization catalyst employed in the ketonization system 124 may be, but it is not limited to, any of several types of metals oxides. These oxides may include, but are not limited to, amphoteric (reducible) metal oxides, such as, but not limited to, cerium oxide (CcCT). titanium dioxide (TiCh), manganese (IV) dioxide (MnCf). zirconium oxide (ZrO?). The catalyst may include pristine (unmodified) or oxides modified in any suitable way necessary. For example, TiO? may be anatase, ZrO? may be sulfated, and CeC>2 maybe combined with copper. Binding agents, such as, but not limited to alumina (AI2O3) or silica (S i O2)- may be employed with the ketonization catalyst. The ketonization catalyst may include any combination of any two or more of these metal oxides or modified metal oxides.

[0052] The ketonization reaction in the ketonization system 124 may be conducted at temperatures >200°C and at atmospheric pressures, or at other temperatures and pressures adequate to result in the desired reaction ketone yields and rates. In some embodiments, the ketonization system is operated at a pressure ranging from atmospheric to about 100 psig, or from about atmospheric to about 50 psig, or from about atmospheric to about 30 psig. In some embodiments, the ketonization system is operated at pressure ranging from atmospheric (760 mm Hg absolute) to about -14 psig (about 36 mm Hg absolute), or from about atmospheric to about -7 psig (about 398 mm Hg absolute) , or from atmospheric to about -3 psig (about 605 mm Hg). In some embodiments, the ketonization system is operated at a nominal temperature in the range of about 150°C to 500°C, or preferably about 200°C to 450°C, or more preferably about 300°C to 450°C. The ketonization reactor product stream 125 primarily includes ketone, water, and CO2. The ketonization reactor product stream 125 exiting the ketonization system 124 is directed to a phase separator 126 (such as a knockout vessel) to separate the three phases: organic (ketones) 129, aqueous (water) 127 and gas (CO2) 128. Though not shown in FIG. 1, the ketonization130647-0244 product stream 125 may optionally be cooled down by any suitable means (e.g., heat exchange with cooling water or other cool streams needing heating) before phase separation. Heat integration is recommended and may be used to recover energy and improve efficiency of the process. The separated CO2 128 may be recycled for use in the extraction process or exported for carbon capture and sequestration to improve the carbon intensity of the process.

[0053] During the ketonization reaction, any C2-C4 VFAs present in the purified MCFAs 123 will react to form short-chain ketones, such as those having a carbon length of C3 through C6. These ketones (C3-C6) are at least somewhat soluble in water; therefore, some of the ketones of this size will end up in the water phase 127, which is undesirable. If the ketone concentration in this water phase 127 is significant, the water phase can be sent to a system to recover the ketones, such as a liquid-liquid extraction system, where ketones having a carbon chain length greater than C6, which are more insoluble in water, are used as the extractant (not shown in FIG. 1). Nevertheless, a small amount of SCFAs may be extracted in extraction 101 and further separation of the water and C2-C4 VFAs 117 from the MCFAs may optionally be performed in an acid separation unit 116 (such as an evaporator or distillation column). Therefore, the resulting amount of short-chain ketones (C3-C6) present in the ketonization reactor product stream 125 is understood to be small, thus minimizing the presence of ketones in water stream 127. The water stream 127 containing a small amount of short-chain ketones or unreacted acids may be recycled to fermentation where, if such is a mixed cultured fermentation or anaerobic digestion, there will be microorganisms there that will be able to convert these ketones into acids. Alternatively, this water stream 127 can additionally or alternatively be sent to a wastewater treatment process, such as anaerobic digestion for methanogenic biogas production, or aerobic treatment, or both.

[0054] The CO2 formed 128 during ketonization together with the CO2 106 exiting the raffinate heater or steam stripper 105 and, optionally, the CO2 vented (not shown in FIG. 1) from the MCFA stream 115 after it is depressurized can be recycled back to a compressor (or compressors) 122. Make-up CO2 121 may be needed. Any needed make-up CO2 is provided to compressor 122 together with the CO2 recycle streams 106 and 128. The pressurized CO2 stream 114 exits compressor 122 and is cooled to the proper temperatures (cooler or cooling heat exchanger not shown) prior to joining stream 111 to form stream 112, which is at the proper pressure to be then pumped or compressed by compressor or pump 113 to the proper pressure for acidification / extraction in extraction column or contactor 101.

[0055] The ketone phase 129 will contain most of the ketones having a carbon length of C7 through C15 (or C17) along with a small quantity of the C3 through C6 ketones. Such carbon chain length fall in the same carbon chain length as certain hydrocarbon fuels such as jet fuel and winter diesel. The ketone phase 129 then undergoes conversion to hydrocarbons by hydrodeoxygenation (HDO) in a HDO reactor 130, where hydrogen 131 is used the presence of a suitable HDO catalyst (e.g., platinum-, palladium-, nickel-based catalysts or other catalysts) to remove the oxygen atoms from the ketones, thus130647-0244 resulting in mostly C9-C17 n-paraffins and water. The hydrodeoxygenated products 138 are provided to a phase separator 132 to separate the water 133 from the newly formed n-paraffins 134. The n-paraffins 134 may undergo further refinement, such as isomerization using the proper catalysts (e.g., Pt / SAPO-11 or other catalysts) in a refining step 135 to produce branched hydrocarbons. Hydrogen 136 may be provided to the refining step 135 as needed. The amount of branching achieved may be adjusted via control of the operating conditions of the refining step 135 to allow the product 137 to meet desired cloud point / freeze point specifications of the final product 137. Alternatively, for instance, if diesel is desired, no further conversion is required. Further distillation may also be done as part of the refining step 135 to get the final product 137 to the proper distillation curve required for the desired hydrocarbon product (e.g., jet fuel, diesel). Ketonization, as a reaction that achieves the proper hydrocarbon fuel carbon chain lengths from C5-C9 VFAs that may be produced from mixed culture fermentation is, therefore, a critical step in the production of renewable or sustainable hydrocarbon fuel, specifically sustainable aviation fuel (SAF) but also diesel and others such as marine fuels.

[0056] As discussed, the ketonization of fatty acids with the above-mentioned catalysts can be an efficient conversion process and achieve near theoretical yields, but has a major drawback in that the water produced by the reaction also inhibits the reaction. Separating the produced water from the resulting ketones and the unreacted fatty acids is easily done when the fatty acids are a long-chain fatty acids (i.e., > 12 carbons in chain length), as in such situation, there is a large boiling point difference between the water and the fatty acids and the water and the fatty acids are highly insoluble in each other. However, this process is not feasible when SCFAs are the reacting VFAs in the ketonization and , though feasible, it is inefficient, when MCFAs (C5-C9 VFAs) are the ketonization feedstock.

[0057] As depicted in FIGS. 11A and 1 IB, a method of producing ketones may include water removal steps to reduce the inhibitory effect of water on the ketonization reaction. In FIG. 11A, in an embodiment, a method of producing ketones 1100 includes a first step in which fatty acids are subjected to ketonization by contacting the fatty acids with a ketonization catalyst. The ketonization product 1115 includes some amount of water, which inhibits the ketonization of the fatty acids, preventing the reaction from reaching maximum conversion. A water removal step 1120 is performed, and the water-reduced ketone stream 1125 is then analyzed in a ketone yield determination step 1130. In some embodiments, the water removal step 1120 reduces the amount of water in the water ketonization product to less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than 1 wt.%, less than 0.5 wt.%, or less than 0.1 wt.%. If the water-reduced ketone stream 1125 has a yield that is at or above a target yield, the stream 1135 is then sent to the product collection step 1140, which may further optionally include other processes on the ketones, such as HDO. Alternatively, if the determined yield of the water-reduced ketone stream 1125 is less than the target yield, may be sent 1138 for another round of ketonization and water removal. Although illustrated as a recycle loop, the subsequent ketonization step 1110, water removal step 1120, and ketone yield determination step 1130 may be performed as additional stages130647-0244 using the same or different equipment from the first iteration of the method. The method may be iterated any number of times as needed to achieve the target ketone yield. Such iteration can be done during the engineering process of the ketonization system, such that the proper equipment may be in place to achieve the target ketone yield.

[0058] Turning to FIG. 1 IB, in another embodiment, a method of producing ketones 1150 includes removal of the water performed simultaneously with the ketonization reaction 1160. The ketonization and water removal step 1160 are performed simultaneously and in the same equipment. The water-reduced ketone stream 1165 exiting the ketonization step 1160 can be analyzed to determine 1170 if the ketone yield meets the yield requirements. If the determined yield is at or exceeds a target yield, the ketone stream 1175 is then sent to a final product collection step 1180, which may include further processing of the ketones by various processes, such as HDO. If the determined yield is not at or above the target yield, the ketone stream 1178 can be sent for further iterations of the ketonization and water removal step 1160. In some embodiments, the target overall yield is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or greater than 99% of the theoretical maximum yield, as determined by stoichiometry and the composition of the ketonization VFA feedstock, equilibrium conditions, or thermodynamic considerations such as the Gibbs free energy of the reaction system or system enthalpy. These subsequent ketonization and water removal steps 1160 may be performed in the same or different equipment than the initial ketonization and water removal step 1160. The method may be iterated any number of times as needed to achieve the target ketone yield. Such iteration can be done during the engineering process of the ketonization system, such that the proper equipment may be in place to achieve the target ketone yield.

[0059] These two main water-removal strategies may be implemented using a variety of methods and equipment. In the following embodiments shown in FIGS. 2-7 and 10, these strategies on how to avoid water inhibition of the ketonization reaction are shown. These strategies may be implemented, for example, within the process shown in FIG. 1 and illustrated as the ketonization system 124 as previously disclosed and described. In this regard, the ketonization system 124 may include a series of equipment based on the embodiments that will be described for FIGS. 2-7 and 10. Particularly, the process steps and equipment illustrated in FIGS. 2-7 and 10 replace the acid separator 116, acid purification unit / system 119, ketonization system 124, and the phase separator 126 and the associated streams of FIG. 1. For the processes and systems illustrated in FIGS. 2-7 and 10, the preparation of the MCFA stream 115 is prepared as discussed with reference to FIG. 1, and then provided to the processes and systems ofFIGS. 2-7 and 10 as MCFA stream 214, 314, 414, 514, 614, 714, or 1014, respectively.

[0060] In the embodiments illustrated in FIG. 2, the acid separator 116, the acid purifier 119, the ketonization system 124, phase separator 126, and other components shown in FIG. 1 are substituted with the equipment illustrated in FIG. 2. In the embodiments illustrated in FIG. 2, an MCFA stream 214130647-0244 (corresponding to stream 115 and prepared as discussed previously) contains mostly C5-C9 VFAs and, optionally, a minor quantity of water and C2-C4 acids. As illustrated in FIG. 2, the water and SCFAs 216 may be at least partially removed from the MCFA stream 214 in a first evaporator or distillation system 215. The remaining MCFA stream 218 is purified by evaporation or distillation 219 to remove any heavy impurities 221. Each separation unit may include a reboiler 217220 to optimize efficient separation of the components. It should also be understood that, although not illustrated in FIG. 2, the separation and purification of the MCFA stream 214 may be performed in a single unit.

[0061] The purified MCFA stream 222 may be heated in one or more heaters 234a to bring the stream 224a to the desired ketonization reactor temperature, which is greater than 200°C, and preferably may be above 300°C, but lower than 500°C, and is preferably lower than 450°C to avoid cracking of the reactants and products and other reactions such as dehydration / dehydrogenation, which forms olefins. In some embodiments, an optional sweep gas 223a, which may be any inert gas (e.g., but not limited to, nitrogen, argon, helium, or preferably CO2) is added to the stream 222 before the stream enters the heaters 234a. Additionally, or alternatively, a vacuum may be pulled after condensers 228a (not shown in FIG. 2) to run this reaction under vacuum, which could be advantageous because the reaction results in a net increase in gas-phase moles (from 2 to 3), which suggests that lower pressure thermodynamically favors the forward reaction in accordance with Le Chatelier’s principle. The stream 224a is fed to a reactor for first ketonization stage 225a with its catalyst bed 226a, which is loaded with one or more ketonization catalysts as previously described for FIG 1 (e.g., but not limited, amphoteric metal oxides and other oxides). The first stage ketonization reactor is the first in a series of several reactor stages, which in FIG. 2 is illustrated as three reactors (i.e., 225a, 225b and 225c). However, FIG. 2 is not meant to be limiting, thus the number of reactors can be any number larger than one, as prescribed by economic optimization, overall conversion targets, or other process considerations, with any intermediate ketonization stage reactors feeding into subsequent reactors. In some embodiments, the ketonization reactors (z. e. , 226a, 226b, 226c) become sequentially larger from the first stage to the last stage in order to achieve the desired high conversion / yields, and in such embodiments the later reactors require larger amounts of catalyst in their catalyst beds than earlier reactors. As the ketonization reaction takes place in the first ketonization stage 225a reactor using catalyst bed 226a, a certain conversion is achieved, which is less than 100%, and likely less than 80% or less than 60%, as necessary to avoid a high water inhibitory effect. As the ketones, water, CO2 and unreacted acids exit the first ketonization stage 225a as a first water and ketones stream 227a, they are cooled down using one or more coolers or condensers 228a to allow most or all of the ketones, acids, and water in the stream to condense, with the CO2 remaining in the gas / vapor phase. The cooled down and partially condensed water and ketones stream 227a after cooler / condenser 228a is sent to a phase separator or knockout drum 229a, where the CO2, the ketones and unconverted acids and the water are separated. Because of the need for the ketones / unconverted acids and water to form a separate phase, the extend of the reaction needs to be appropriate for the two phases to form. The extent of the reaction in this first ketonization stage 225a and130647-0244 the catalyst bed 226a is expected to be >50%, but is preferably >60% of the maximum theoretical yield. In phase separator or knockout drum 229a, the first amount of water 23 la is separated from the ketones and unreacted acids to produce a water-reduced stream 232a. Although water and C9-C17 ketones expected from the C5 - C9 VFAs fed have very low solubility, it is expected that some of the acids, namely C5 and C6 VFAs, will be partly dissolved in the water phase, which could represent a loss, but they would more than likely be recycled within the process to fermentation or to acid extraction to minimize any such losses. CO2 and, optionally, the sweep gas are also separated 230a in this first phase separator or knockout drum 229a, which together with homologous CO2 streams 230b and 230c may be recycled back to extraction as described for FIG 1. The separator or knockout drum 229a is operated at conditions such that the water-reduced stream 232a comprised of C9-C17 ketones and C5-C9 acids contains less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than 1 wt.%, less than 0.5 wt.%, or less than 0.1 wt.% water. The water-reduced stream 232a, comprising C9-C17 ketones and C5-C9 acids (with a small amount of C4 acids) is then pumped using pump 233a and fed together with, optionally, sweep gas 223b to heater 234b before being fed into the second ketonization stage 225b for ketonization in catalyst bed 226b. Additionally, or alternatively a vacuum may be pulled after condensers 228b (not shown in FIG. 2).

[0062] The system equipment and process steps are then followed again as described for the first stage, with each stream and piece of equipment labeled with the same number but with “b” denomination instead of “a.” In other words, a second water and ketone stream 227b is generated by the second ketonization stage 225b, which is then condensed by one or more condensers 228b before being fed to a second phase separator or knockout drum 229b. The CO2 (and any sweep gas) present in the second water and ketone stream 227b exits the knockout drum 229b as a second CO2 stream 230b, while the water is taken as a second aqueous stream 23 lb from the lower portion of the second knockout drum. The second water-reduced ketone stream 232b, which also contains some amount of unreacted VFAs, is then pumped back up to pressure by one or more pumps 233b to prepare for use in a third ketonization stage. In some embodiments, the knockout drum 229b is operated such that the amount of water in the second water-reduced ketone stream is less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than 1 wt.%, less than 0.5 wt.%, or less than 0.1 wt.%.

[0063] After the second stage 225b, the process may be iteratively repeated with additional stages, as needed to achieve overall efficiency or conversion targets, or for other considerations. For example, in some embodiments, the additional ketonization stages may be added to the process / system to achieve a target overall conversion of the fatty acids to ketones. In some embodiments, the target overall conversion is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or greater than 99% of the theoretical maximum conversion, as determined by stoichiometry and the composition of the ketonization VFA feedstock,, equilibrium conditions, or thermodynamic considerations such as the Gibbs free energy of the reaction system or system enthalpy. Each additional iterative stage is configured for130647-0244 contacting the products of the previous stage with a ketonization catalyst to produce a subsequent product stream, which is then subjected to water removal steps as previously described.

[0064] The process and system as illustrated in FIG. 2 includes a last stage (shown as a third ketonization stage 225c, in FIG. 2) with one or more heaters 234c, a catalyst bed 226c, one or more condensers 228c, and a final phase separator or knockout drum 229c used to process the third water and ketone stream 227c, as previously discussed. Finally, after the final phase separator or knockout drum 229c, the resulting C9-C17 ketones in the final ketone stream 232c, should have a high near-theoretical yield. The final C9-C17 ketone stream 232c may be used for many purposes in the chemical industry, such as solvents, but specifically for producing biofuels. This stream may then be pressurized using pump 233c and sent downstream to hydrodeoxygenation to produce hydrocarbons and be processed as described for FIG. 1. Similarly, the last stage can improve reaction efficiency with a sweep gas 223c injected into the system or vacuum that may be pulled after condenser 228c.

[0065] Interstage Flash or Distillation Units

[0066] The processes and systems illustrated in FIG. 2 use phase separators or knockout drums (229a / 229b / 229c), which condense the water in the ketone, CO2 and water streams (227a, 227b, 227c) and also requires a significant extent of conversion even after the first stage to ensure that phase separation occurs. With reference to FIG. 3, in some embodiments processes and systems may use separation vessels 329a, 329b and 329c in place of the phase separators or knockout drums. The separation vessels 329a 329b 329c may be, but are not limited, to knockout drums, flash vessels, or distillation towers configured to condense only the C9-C17 ketones and the unreacted C5-C9 VFAs, while operating at conditions that keep water and CO2 in the vapor phase for the separation process. As with the embodiments illustrated in FIG. 2, the equipment and process steps illustrated in FIG. 3 may be employed in place of the ketonization system 124 and phase separators 126 shown in FIG. 1. Operating the separation vessels 329a 329b 329c at the indicated conditions is feasible due to the difference between the boiling points of the C9-C17 ketones and water is > 50°C, allowing for flash or distillation processes to perform the separation while maintaining high levels of energy efficiency. The water, the CO2 and, optionally, sweep gas exit the top of the separators 329a, 329b and 329c as vapor from partial condensers 332a / 332b / 332c and are sent to a separate knockout drum (not shown) to allow water to condense and to separate the CO2 from the water so that the CO2 can be recycled for reuse, as described for the system illustrated in FIG. 1. Additionally, or alternatively a vacuum may be pulled after condensers partial condensers 332a / 332b / 332c (not shown in FIG. 3) to run the system in a vacuum and avoid or minimize the need for sweep gas.

[0067] The system depicted in FIG. 3 has an advantage in that the separation units 329a (such as, but not limited to a knockout drum or distillation column) can effectively separate the water from the fatty acids and ketones without requiring as high of a rate of conversion of the fatty acids to ketones in130647-0244 the first ketonization stage (326), compared to the phase separator or knockout drum 229a shown in the system illustrated in FIG. 2. Additionally, the system illustrated in FIG 3. avoids the energy requirements of condensing the water as part of the separation process, given that the water is separated as a vapor together with the CO2 and, optionally, the sweep gas in the knockout drums or distillation columns 329a 329b 329c. Nonetheless, the processes and systems shown in FIG. 2 and FIG. 3 require the C9-C17 ketones and unreacted acids to be condensed for separation from the water and re-vaporized before feeding to the next ketonization stage.

[0068] Embodiments are presented in FIGS. 4-7 and in FIG. 10 that avoid the need for condensation and re -vaporization of the C9-C17 ketones after each reaction stage. As noted previously, the equipment and process steps illustrated in FIG. 4 replace the acid separator 116 (415 in FIG. 4), the acid purifier 199 (419 in FIG. 4), the ketonization system 124, and the phase separator 126 of FIG. 1. In the embodiments illustrated in FIG. 4, three ketonization stages (425a, 425b and 425c) are employed, but this illustration should not be limiting as any number of stages greater than one may be employed as prescribed by economic optimization, process efficiency, conversion criteria, or other considerations. Apart from the differences described below, the streams and equipment shown in FIG. 4 and labeled as 400s correspond to the streams and equipment labeled as 200s in FIG. 2, and thus the previous descriptions of these streams and equipment apply to the similar steps and parts in FIG. 4, with the primary differences being the method and equipment used for interstage water removal, as will be described.

[0069] FIG. 4 makes use of high-temperature molecular sieves (i.e., 431a-a and 431a-b and 43 Ib-a and 43 Ib-b) to absorb the water. In this regard, the partially converted stream 427a exiting the first ketonization stage 425a is cooled as necessary using cooler 428a or heat exchanger and fed to one of the two molecular sieve beds (either 43 la-a or 43 la-b). The molecular sieves are implemented as parallel pairs so that as a first molecular sieve becomes saturated with water, it can be taken from operation and regenerated while the second molecule sieve operates to separate the water from the ketone, CO2 and water stream 429a. Thus, while the stream 429a containing the C9-C7 ketones, unconverted acids, water and CO2 are fed to one of the beds, the other one is regenerated typically through heating. When the first sieve becomes saturated, the stream 429a can be directed to the second sieve while the first is then regenerated. It is important to note that the two parallel molecular sieves (43 la-a and 43 la-b) are illustrative, as it is possible that more than two beds would be needed depending on the time required for regeneration. For example, in some processes, the molecular sieve equipment may be sized such that 3, 4, 5, or greater than 5 molecular sieves in parallel are required.

[0070] The ketone, CO2 and water stream 427a from the first ketonization stage 425a is cooled by a cooler or heat exchanger 428a, or other cooling device, to a temperature that is adequate for the water absorption to take place, while minimizing or avoiding condensation of the components in the130647-0244 stream 427a. The cooled vapor stream 429a is then fed to the high-temperature molecular sieves using a series of valves (430a-a, 436a-a, 430a-b, 436a-b, 433a-a, 437a-a, 433a-b, 437a-b) to align with the operating molecular sieve bed while the other bed is regenerated. The molecular sieve 43 la-a 43 la-b remove the water from the cooled vapor stream 429a to produce a water-reduced ketone / unreacted VFA stream 424b. In some embodiments, the molecular sieve 43 la-a 43 la-b operates to reduce the amount of water in the stream to less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than 1 wt.%, less than 0.5 wt.%, or less than 0.1 wt.%. The water-reduced ketone / unreacted VFA stream 424b leaving the molecular sieve is then sent to a second ketonization stage 425b, where heater 434b is used to heat the water-reduced ketone / unreacted VFA stream 424b to a temperature sufficient for the ketonization reaction, as mentioned in the description for the system of FIG. 1.

[0071] During regeneration of the molecular sieve bed, the valves (430a-a, 436a-a, 430a-b, 436a-b, 433a-a, 437a-a, 433a-b, 437a-b) are aligned with hot air or a hot inert sweep gas 435a, which is fed through the beds during regeneration. The regeneration exit stream 438a containing the sweep gas and the desorbed water is passed through a cooler 439a to condense water and remove it from the inert gas. Alternatively, the regeneration exit stream 438a is joined with the regeneration exit stream 438b and both are sent to one condenser to condense the water, which results in capital expense savings. Finally, cooled stream 440a (and 440b) containing the condensed water and the sweep gas is sent to a knockout drum 441a, which, as mentioned, can be the same unit 441b used for the second ketonization stage 425b.

[0072] The second ketone, CO2 and water stream 427b (also containing some amount of unreacted VFAs) exiting the second ketonization stage 425b is cooled using one or more heat exchangers 428b to produce a second vapor stream 429b. The second vapor stream 429b is then fed to a second set of molecular sieves 43 Ib-a 43 Ib-b for removal of the water. As above, a series of valves (430b-a, 436b-a, 430b-b, 436b-b, 433b-a, 437b-a 433b-b, 437b-b) are used to provide the second vapor stream 429b to the operating molecular sieve bed while the other bed is regenerated. In some embodiments, the molecular sieve 43 Ib-a 43 Ib-b operates to reduce the amount of water in the stream to less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than 1 wt.%, less than 0.5 wt.%, or less than 0.1 wt.%. The second water reduced ketone stream 424c is heated using one or more heat exchangers 434c and then fed to the last ketonization stage 425c. It should be understood that the processes and equipment described for the second ketonization and water removal steps may be duplicated as many times as desired to achieve the overall VFA conversion desired. Though only three ketonization steps are illustrated in FIG.4, additional steps can be readily included.

[0073] For the last ketonization stage 425c, the ketone product stream 427c is fully condensed when passing it through one or more coolers 428c and the ketone product stream is sent to a phase separator or knockout drum 429c to separate the water phase from the ketone phase and the CCMswccp gas. Condensation of the ketones in this manner allows the use of a pump 433c to increase the pressure to130647-0244 HDO conditions and avoid the use of high-temperature compressors. Nonetheless, the option to use a high-temperature compressor to avoid having to cooled down the product stream 427c after the last ketonization stage should also be considered and thus the water / ketone separation step for the last ketonization step may also be a molecular sieve system similar to those after the first (425a) and second (425b) ketonization step.

[0074] FIG. 5 illustrates systems and processes according to various embodiments. The streams and pieces of equipment denoted 500s in FIG. 5 correspond to the streams and pieces of equipment labeled as 200s in FIG. 2 and as previously described, apart from the differences described herein. In the process and system illustrated in FIG. 5, the molecular sieves have been incorporated into parallel ketonization reactors 525a 525b. In each ketonization reactor 525a 525b there is a stacked bed comprising ketonization catalyst beds 526a 526b, such as the catalysts as described in detail above with reference to the system and process depicted in FIG. 1, alternating with molecular sieve beds 527a 527b. As depicted in FIG. 5, the ketonization catalyst beds 526a 526b may include 3 ketonization beds 526a 526b, denoting three separate ketonization stages, with a molecular sieve beds 527a 527b sandwiched between ketonization stages. It should be understood that the use of three stages in FIG. 5 is illustrative only, as the number of ketonization stages is not particularly limited. Any number of ketonization stages greater than two may be employed as prescribed by economic, efficiency, overall conversion, or other considerations. The use of two parallel reactors (525a and 525b) should also not be considered as a limitation, as the number of reactors will depend on the proper timing needed for regeneration of the molecular sieve beds and / or the ketonization catalysts. Conveniently, hot air provided to the reactor undergoing the regeneration process can regenerate both the ketonization catalyst and the molecular sieves. The hot air can serve to remove coking from the ketonization catalyst and cause water desorption to regenerate the molecular sieves. Directing the VFA feed stream 524 to the proper regenerated reactor and directing the hot air or hot inert gas 529 for regenerating the molecular sieve is done by properly aligning valves (542a, 543a, 543b, 542b). The flow of the product stream 528 and regeneration stream 530 is controlled by the valves 544a 544b 545a 545b. The product stream 528 may be sent to an optional condenser to condense ketones and any leftover water. The product stream is sent to a knockout drum 536, where any remaining water 538 or CO2 537 is removed. The resulting C9-C17 ketones 539 are then provided to one or more pumps 540, which pressurizes the ketones 541 for a downstream reaction that requires high pressure, such as HDO. On the other hand, the regeneration exit stream 530 from the regeneration cycle is sent through a condenser 531 and then sent to a knockout drum 533 where condensed water 535 is separated from the inert gas or air and a little bit of CO2 534 which is generated from coking removal.

[0075] The processes and systems illustrated in FIGS. 4 and 5 avoid the condensation / re-vaporization swings that are present in the processes and systems illustrated in FIGS. 2 and 3. High-temperature ceramic membranes present another way to remove water. FIG. 6 illustrates a process and130647-0244 system that uses high-temperature ceramic membranes for this purpose. The process and system illustrated in FIG. 6 are similar to the processes and systems shown in FIGS. 2, 3, and 4 where illustratively three ketonization stages (625a, 625b and 625c) are employed, but this illustration should not be limiting as any number of stages greater than one may be employed as prescribed by economic optimization, overall conversion requirements, or other considerations. Process and systems illustrated in FIG.6 are similar to those illustrated in FIGS. 2, 3, and 4 such that streams and pieces of equipment in FIGS. 2, 3, and 4 labeled as 200s, 300s and 400s, respectively, correspond to streams and equipment labeled as 600s in FIG. 6, and so the preceding descriptions provided for these streams and processes apply to those in FIG. 6, with the exception of the streams and equipment associated with the water removal portions of the process and unless otherwise described. For example, the mixed VFA or MCFA stream 614 is similar the MCFA stream 214 discussed with reference to FIG. 2, etc.

[0076] The process and system illustrated in FIG. 6 use high-temperature membranes 63 la and 63 lb which are permeable to water to remove the water from the first and second ketone, CO2 and water streams 627a 627b produced in the first and second ketonization stages 625a 625b, respectively. As described above in reference to the processes and systems illustrated in FIG. 2, a stream containing VFAs is separated and purified, then the purified VFA stream 622 is sent to a first ketonization stage 625a having a ketonization catalyst bed 626a to produce a first ketone, CO2 and water stream 627a. The partially converted first ketone, CO2 and water stream 627a exiting the first ketonization stage 625a is pressurized using one or more compressors 628a to a predetermined pressure sufficient for separating the water using the high-temperature membrane 63 la. The pressure may vary based on the membrane being used, but in some embodiments the pressure is about 5-25 psig, or from 5-50 psig, or from 10-20 psig, or is greater than 50 psig and less than 100 psig. The first ketone, CO2 and water stream 627a is cooled as necessary using one or more coolers 633a to a temperature suitable for membrane filtration, which in some embodiments is about 300 °F - 500 °F, or about 200 °F - 300 °F, or about 250 °F - 300 °F, or about 150 °F - 250 °F, or about 200 °F - 250 °F, or about 300 °F - 350 °F, or about 350 °F - 400 °F. The cooling of stream 629a is done to a temperature that is adequate for the proper functioning of the membranes 63 la, while at the same time minimizing condensation of the components in stream 629a. The pressurized ketone and water stream 629a is provided to the first high-temperature membrane 63 la, which causes at least a portion of the water in the stream to pass through the membrane to be collected as a water exit stream 638a. A sweep gas (e.g., but not limited to, nitrogen, air) 635a is passed on the other side of the membrane to sweep the water as it makes its way through. Additionally, or alternatively, a vacuum may be pulled on the other side of the membrane. The ketones do not pass through the membrane and are produced from the membrane 63 la as a water-reduced ketone / unreacted VFA stream 632a. In some embodiments, the water-reduced ketone / unreacted VFA stream 632a contains less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than 1 wt.%, less than 0.5 wt.%, or less than 0.1 wt.% water. The exiting water-reduced ketone / unreacted VFA stream 632a then goes through a130647-0244 pressure-reducing device 634a, which may be a throtling valve or a turbine to recover a portion of the compression energy.

[0077] The water-reduced ketone / unreacted VFA stream 632a becomes the feed for the second ketonization stage 625b. One or more heaters 630b or heat exchangers are used to adjust the temperature of the water-reduced ketone / unreacted VFA stream 632a to that sufficient for the second ketonization stage 625b. The water-reduced ketone / unreacted VFA stream 632a is then sent to the second ketonization stage 625b for additional conversion of the unreacted VFAs in the water-reduced ketone / unreacted VFA stream 632a to ketones and water, which are produced as a second ketone and water stream 627b. In some embodiments, the second ketones and water stream 627b contains less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than 1 wt.%, less than 0.5 wt.%, or less than 0.1 wt.% water. The second ketone and water stream 627b is then pressurized using one or more compressors 628b to produce the second pressurized ketone stream 629b, which comprises ketones, CO2 and water at elevated pressure. In some embodiments the second pressurized ketone stream 629b is pressurized to about 5-25 psig, or from 5-50 psig, or from 10-20 psig, or is greater than 50 psig and less than 100 psig. The second pressurized ketone stream 629b is then passed through one or more coolers 633b or heat exchangers, which cool the stream to temperatures suitable for the high-temperature membranes, before being the stream is fed to the high-temperature membrane 63 lb to produce a second water exit stream 638b and a second water-lean ketone and unreacted VFA stream 632b. In some embodiments, the second pressurized ketone stream 629b is cooled to about 300 °F - 500 °F, or about 200 °F - 300 °F, or about 150 °F - 250 °F.

[0078] The first and second membrane water exit streams 638a 638b containing the sweep gas and the extracted water may be treated in the same equipment or separately. In an embodiment, the first membrane water exit stream 638a is passed through a cooler 639a to condense the water and remove it from the inert sweep gas; the cooled stream 640a containing the condensed water and the sweep gas is sent to a knockout drum 641a. When performed separately, the second membrane water exit stream 638b is passed through a separate cooler 639b and then to a second knockout drum 641b. Alternatively, the membrane water exit stream 638a is joined with the membrane exit stream 638b and both are sent to one condenser to condense the water and then on to a knockout drum.

[0079] The process described above for the first and second ketonization steps may be repeated for any other intermediate ketonization steps present. For the last ketonization stage 625c (presented as a third ketonization stage in FIG. 6), the process is repeated for a final time, with some differences. The second water-reduced ketone and unreacted VFA stream 632b of the previous stage, shown as the second stage in FIG. 6, is at least partially decompressed in a pressure reduction device 634b, which may be a throtling valve or a turbine configured to recover a portion of the compression energy, and then heated using one or more heat exchangers 630c to bring the stream temperature to a temperature sufficient for130647-0244 any unreacted VFAs in the stream to undergo ketonization reactions in the last ketonization stage 625c. The last ketonization stage 625c contains a ketonization catalyst bed 626c, as described for the previous stages, which converts at least a portion of the unreacted VFAs to ketones and water, resulting in a last ketone and water stream 627c.

[0080] Unlike the previous ketonization stage products, the last ketone, CO2 and water stream 627c is fully condensed when passing it through the one or more coolers 633c and is sent to a phase separator or knockout drum 641c to separate the water phase 643c from the ketone phase and the CCf / swccp gas 642c. The last ketone phase is the ketone product stream 644c and contains primarily C9-C17 ketones. The ketone product stream 644c may contain substantially no water (<1%). Full condensation of the ketones is suggested because it allows the use of a pump 645c to increase the pressure to HDO conditions (see pressurized ketone stream 646c) for further processing and avoids the use of high-temperature compressors. Nonetheless, the option to use a high-temperature compressor to avoid having to cool down the product stream 627c after the last ketonization stage should also be considered and thus the last ketone / water separation step, in some embodiments, can be another membrane system similar to 63 la and 63 lb.

[0081] FIG. 7 illustrates processes and systems according to other embodiments. In FIG. 7, processes and systems are illustrated that make use of one or more high-temperature membranes to remove water after every ketonization stage. FIG. 7 discloses an embodiment similar to FIG. 2 with most of the streams and pieces of equipment denoted as 200s corresponding to the streams and pieces of equipment labeled as 700s in FIG. 7. The discussion of the like-numbered streams and equipment shown in FIG. 2 also apply to the similar streams and equipment illustrated in FIG. 7 if not discussed further herein. For example, the mixed VFA or MCFA stream 714 is similar the MCFA stream 214 discussed with reference to FIG. 2, etc.

[0082] Comparing the embodiments illustrated in FIG. 7 to those illustrated in FIG. 6, the high-temperature membranes 727a 727b have been incorporated into the ketonization reactor as a ketonization / water removal system 725a, positioned between ketonization catalyst beds 726a, 726b and 726c. As a result, there is a stacked bed, where beds 726a, 726b and 726c are ketonization catalyst beds, using suitable ketonization catalysts as described previously, and compartments 727a and 727b are membrane systems. The ketonization catalyst beds 726a, 726b and 726c consists of 3 beds, denoting three separate ketonization stages, with a high-temperature membranes 727a 727b after each ketonization stage. As with previously discussed embodiments, the number of ketonization stages is illustrative as any number of stages more than one may be used, as prescribed by economic optimization, overall conversion targets, or other considerations. As discussed in other embodiments, a mixed MCFA stream 714 is separated and purified, then provided to a ketonization reactor / water removal system 725a. The product stream 728 exiting the ketonization reactor / water removal system 725a is then optionally sent to130647-0244 a cooler or condenser 729 to condense ketones and any leftover water and separate the CO2. The condensed product stream is then sent to a knockout drum 736, where remaining water 738 and / or CO2 (and sweep gas, which may have optionally been added 723) 737 is removed. The resulting C9-C17 ketones 739 are then sent downstream to its final purpose, which in FIG. 7 is illustrated to be a pump 740 to pressurize the ketones 741 for downstream processes that require high pressure, such as HDO. The water stream 730 exiting the other side of the membranes contains the water that went through the membrane and, optionally, a sweep gas (e.g., but not limited to, nitrogen, air), which may be added to the inlet (735a and 735b) to aid in the sweeping of the water. This water stream 730, which is the consolidation of the streams leaving the membrane compartments, is sent through a condenser 731 and then sent to a knockout drum 733 where condensed water 735 is separated from the sweep gas 734.

[0083] The embodiments in FIG. 2 through 7 include a plurality of ketonization stages to remove water after every stage and minimize the water inhibition effect on the ketonization reaction. Although these embodiments represent an improvement compared to a ketonization system where water is not removed, further improvements may be provided via in situ removal of water as it is formed in the ketonization stage. In one embodiment, proper ketonization catalysts as described for the embodiments illustrated in FIG. 1 (e.g., but not limited to, amphoteric metal oxides and other oxides) are loaded into the ketonization stage on a first side of a suitable membrane system. The membrane is configured to permit water on the first side to move to a second side of the membrane directly from the reaction zone as the water is formed. See, e.g., de la Iglesia, provided below. FIG. 8 illustrates this configuration.

[0084] According to an embodiment as illustrated in FIG. 8, Option A, the catalyst include catalyst pellets 807a loaded outside of a membrane tube 801a (shown as dashed lines for clarity). As the VFAs 802a are fed to the side where the pellets are, the VFAs are converted to ketones and CO2 803a and water (H2O). The ketones and CO2 803a are carried away, but the water 805a travels across the membrane to the inside of the membrane tube 801a where a sweep gas 804a assists in carrying the water away 806a. A detailed view illustrates details of a portion of the membrane tube 801a where the layer of ketonization catalyst pellets 807a are positioned outside of the membrane. The detailed view also shows that the membrane tube 801a may be formed of constituent layers, including a separation membrane layer 808a and a support layer 809a.

[0085] In another embodiment, illustrated in FIG. 8, Option B, the catalyst pellets 807b are loaded in the inside of the membrane tube 801b with the VFAs 802b fed to the inside of the tube such that the VFAs contact the ketonization catalyst pellets and are converted into ketones and CO2 803b, which exit through the same interior of the membrane tube. Meanwhile, the water 805b, which is also formed in the interior of the membrane tube, is transported across the membrane by a gradient caused by the sweep gas 804b and thus it is carried away 806b on the outside of the membrane tube 801b. Details of the membrane tube 801b are shown in the detailed view, where the layer of ketonization catalyst pellets130647-0244 807b are shown on the inside of the membrane tube 801b, and the membrane is shown to be formed of a separation membrane layer 808b and a support layer 809b.

[0086] In another embodiment, as illustrated in FIG. 9, in situ water removal during the ketonization reaction is performed by a water-permeable membrane which also has catalytic activity. Similar membranes have been studied for other reactions and have been tested with amphoteric oxides, such as zirconia as one of the catalytic components of the membrane. Membranes with these properties play a dual duty in the ketonization process by both catalyzing the reaction and at the same time removing in situ water from the reaction zone. In FIG. 9, Option A, a membrane tube 901a is provided having catalytic activity on an outside surface or portion of the membrane tube 901a. In the illustrated embodiment, the VFAs 902a are fed to the outside of the membrane tube 901a, the outside being the catalytic side, where the VFAs are converted to ketones and CO2903a and water (H2O). The ketones and CO2 903a are carried along the outside of the membrane tube 901a, but the water 905a passes across the membrane to the inside of the membrane tube where a sweep gas 904a assists in carrying the water away 906a. Details of the membrane tube 901a are shown in the detailed view of FIG. 9, Option A, in which the membrane tube is shown to be formed of two or more layers including the layer with the ketonization catalytic activity 907a at or adjacent to the outside of the membrane tube and the membrane is further formed of a separation membrane layer 908a and a support layer 909a.

[0087] Alternatively, FIG. 9, Option B illustrates a membrane tube 901b having catalytic activity on or adjacent to the inside of the membrane tube. The VFAs 902b are fed to the inside of the membrane tube 901b where they are converted by the catalytic activity of the membrane tube, producing ketones and CO2 903b, which exit through the interior of the tubes. Meanwhile, the water 905b, which is formed in the inside of the membrane tube, is transported across the membrane by a gradient caused by the sweep gas 904b and thus it is carried away 906b on the outside. Details of the membrane tube 901b are shown where the layer with the ketonization activity 907a is on or adjacent the inside surface of the membrane tube and then the membrane tube is further formed by a separation membrane layer 908b and a support layer 909b.

[0088] Embodiments featuring in situ water removal during the ketonization stages, as illustrated shown in FIG. 8 and 9, for example, can now be applied to a system and process for ketonization of VFAs, as illustrated FIG. 10. FIG. 10 shows another embodiment that makes use of high-temperature membrane to remove water but incorporates the concepts described for FIG. 8 and 9. FIG.10 discloses an embodiment similar to the processes and systems described in FIG. 2 through 7 with most of the streams and pieces of equipment denoted as 200s, 300s, 400s, 500s, 600s, and 700s in FIGS. 2, 3, 4, 5, 6 and 7 , respectively, corresponding to the streams and pieces of equipment labeled as 1000s in FIG. 10. In the embodiment illustrated in FIG. 10, the ketonization reactor 1025a includes a membrane system where ketonization catalyst pellets have been loaded in the inside 1026a of the tubes as in FIG. 8,130647-0244 Option B or where the membrane itself has catalytic activity at or adjacent the inside portion of the membrane, as in FIG. 9, Option B. Alternatively, in another embodiment also illustrated in FIG. 10, the ketonization reactor 1025b includes a membrane system where ketonization catalyst pellets are been loaded at the outside 1026b of the tubes as illustrated in FIG. 8, Option A or where the membrane itself has catalytic activity at or adjacent the outside of the membrane tube, as in FIG. 9, Option A. In some of these embodiments, the membrane system is the ketonization reactor 1025a or 1025b. Using any of these reactor configurations that provide in situ water removal during the ketonization reaction may advantageously provide increased reaction efficiency as far as rates and conversion compared to previous embodiments described herein because, as mentioned, water is removed from the reactor zone as it is formed, which minimizes any water inhibition and thus avoids the need for multiple separate ketonization stages. The product stream 1028 exiting the ketonization reactor 1025a (or 1025b) is then optionally sent to a condenser 1029 to condense the ketones and any leftover water in the product stream 1028. The condensed stream is then sent to a knockout drum 1036, where remaining water 1038 and / or CO2 1037 (and any sweep gas that may have optionally been added 1023) is removed. The resulting COC I 7 ketones 1039 are then sent downstream for further processing. For example, in the embodiments illustrated in FIG. 10, the ketones 1039 are sent to a pump 1040, which pressurizes the ketones 1041 for a downstream reaction that requires high pressure, such as HDO. On the other hand, the water stream 1030 exiting the other side of the membranes contains the water that went through the membrane and a sweep gas (e.g., but not limited to, nitrogen, air), which is added to the inlet (1032) to aid in the sweeping of the water as previously described with references to FIGS. 8 and 9. This water stream 1030 is sent through a condenser 1031 and then sent to a knockout drum 1033 where condensed water 1035 is separated from the sweep gas 1034.

[0089] In any of the configurations discussed above in reference to FIGS. 1-7 and 10, the goal of the illustrated processes and systems is to achieve high conversion and selectivity of the ketones from the VFAs. Ketonic decarboxylation is known to be able to achieve near theoretical yields of ketones from fatty acids and beyond having the proper reactor size and stages to achieve such yields, it is also possible to recycle the product back to the last stage to increase VFA conversion.

[0090] While certain embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with ordinary skill in the art without departing from the technology in its broader aspects as defined in the claims.

[0091] EXAMPLE:

[0092] A flow heated reactor was used for ketonization and consisted of a 1” seamless stainless-steel tube with 0.049” wall thickness. The tube is divided into three zones, each with an independent heater and internal and external thermocouples. Zone 1 was filled with inert silicon carbide (SiC) and is for preheating and injection / vaporization of the VFA liquid feed. Zone 2 was the reaction zone packed130647-0244 with catalyst. Zone 3 was filled with inert SiC and served to keep the bottom of Zone 2 at reaction temperature and to keep the reaction product stream in the vapor phase until it reaches the condenser. The tubing from the reactor to the condenser was also heat-traced. Each zone consists of two 2” band heaters wired in parallel. The reaction zone (Zone 2) was controlled by a PID controller using an internal thermocouple, while the other two zones and heat traces are controlled manually with a Variac. An overtemperature safety shutoff was set to 500°C on the external (skin) reactor temperature.

[0093] VFAs were injected with an HPLC pump through a 1 / 16” stainless steel tubing that is inserted into the injection zone of the reactor. Carrier or sweep gas (N2 or CO2) entered the reactor upstream of the injection zone and was controlled by a 1 SLM thermal mass flow controller. The vapor phase ketones, CO2 and water products were condensed in a cold trap with ice and further a 2ndtrap with dry ice was used to ensure no losses. Gases leaving the cold traps were identified and quantified with an online micro-GC that samples the product gas every 3 minutes.

[0094] Organic phases were analyzed for water content by Karl Fischer (KF) titration using a Mettler Toledo V20 Titrator. The ASTM E203-08 method, Standard Test Method for Water Using Volumetric Karl Fischer Titration, is used. The sample, containing a maximum of 100 mg of water, is dissolved in methanol, and titrated with KF reagent, which consists of iodine, sulfur dioxide, organic base, and methanol. The titration end point is determined potentiometrically with a platinum electrode which senses a sharp change in cell resistance when the iodine is reduced by sulfur dioxide in the presence of water. The sample mass is measured by weighing a full pipette, dropping several drops into the methanol, then re-weighing the pipette.

[0095] Liquid samples were analyzed by GC-MS / FID to determine chemical compositions. The GC-MS / FID instrument splits the sample as it exits the column so one fraction is sent to a mass spectrometer for compound identification and the other fraction is sent to a Poly Arc™ reactor for quantifying products. The Poly Arc™ consists of a methanation reactor that converts all hydrocarbons to methane that is quantified using a flame ionization detector. The split sample provides comprehensive species identification and quantitative carbon detection while mitigating the challenge of understanding how much of the sample is analyzed and using multiple calibration mixtures to quantify products with varying response factors, since all hydrocarbons are converted to methane. The GC-MS / FID can analyze only the semi-volatile components of the sample so only compounds that vaporize at or below the GC oven temperature (300°C) are deposited on the column and detected. Initial runs with the existing HP-5 column had broad acid peaks and quantification was unreliable. A 30 m x 0.320 mm x 0.25 pm J&W DB-FATWAX Ultra Inert column was purchased from Agilent for the project because it is an application-specific PEG-type column designed for separation of fatty acid methyl and ethyl esters (FAMEs / FAEEs) from fatty acids.130647-0244

[0096] The heated flow reactor was initially loaded with zirconia-based catalyst (~42 ml). Before loading, the catalyst extrudates were gently crushed in a mortar and pestle to break up very long extrudates, and particles smaller than 2,000 pm were removed via sieve. The reactor was loaded with 40.78 g of ground catalyst (powder testing). Additionally, the ketonization catalyst was initially calcined in a muffle furnace in static air at 500°C (ramp rate 5°C / min) for 2 h. Subsequent catalyst regeneration and calcination was conducted in situ in the flow reactor using a compressed air cylinder with 500 seem flow at 1 atm and 500°C.

[0097] For each experiment, the cold traps were cooled before the reactor was heated to temperature under N2 or CO2 flow. After stabilizing at the reaction temperature, the VFA feed was started and temperature in each zone was monitored and recorded. After completion of the reaction, the pump was stopped and the carrier gas continued to be fed until the product (CO2) generation stopped. The products were collected from the cold traps, separated by gravity and decanted into aqueous and organic phases, and quantified gravimetrically. The VFA feed flask was weighed before and after each reaction to determine the amount fed.

[0098] Total Acid Number (TAN) was measured by titration with a 0.0 IM KOH in IPA solution in the presence of phenolphthalein pH indicator. Typically, 0.25 g of ketone sample was dissolved in 100 ml IPA and ~1 ml of indicator was added. The KOH solution was then added dropwise via syringe until the endpoint, which was indicated by a slight red / purple hue that remained for at least ~1 minute. The weight of the syringe before and after the titration was used to calculate TAN.

[0099] The chemical composition of both aqueous and organic phases was analyzed by GC- MS / FID to determine the carbon distribution of the ketone intermediates and extent of conversion based on residual VFA in the products. TAN titration of the organic phases was also performed. The TAN results were in good agreement with acid concentrations calculated from the GC-MS / FID analyses

[0100] Ketonization process conditions were initially established for the catalyst. The first test used 100 seem of nitrogen as the sweep gas and a VFA flow rate of 0.5-1.5 ml / min, achieving an LHSV of 0.7-2.1 h1. Starting temperature was 350°C and the experiments were run at atmospheric pressure. Conversion at these conditions was 50% or less. Temperature was increased in 25°C increments at 0.5 ml / min VFA feed-rate and a 200 seem N2 sweep gas flow rate. At 425 °C, decomposition products (alkenes) were detected in both the online micro-GC and the product mixture GC-MS. The optimum conditions for ketonization were determined to be 410-420°C and 1 atm.

[0101] Initial experiments with the fermentation-derived feedstock showed 98% mass balance and 94+% theoretical yield of VFAs to ketones at an liquid hourly space velocity (LHSV) of 0.7 h1. A finer temperature sweep was then performed in 5 °C increments to further refine the temperature. After130647-0244 determining an optimum temperature of 415°C, extended production runs were started with the goal of producing as much ketone product as possible. The % theoretical yield obtained were >97%.

[0102] The system was run for 24 h / day during the workweek, only stopping the feed to collect product once per day. During this long-term testing, catalyst deactivation was observed and identified as a slow decrease in CO2 concentration in the gas effluent overtime. This deactivation was caused by coking. The loss in activity could be compensated by increasing the temperature slightly, but cracking at higher temperature was a concern. Thus, an in situ oxidation procedure was performed to remove coke and regenerate catalyst activity at the lower temperature. The catalyst was heated to 500°C overnight under a flow of CO2-free compressed air.

[0103] Ketonization was found to proceed similarly when the sweep gas was switched from N2 to CO2. Because total mass balance is calculated from CO2 concentration, it could not be measured when CO2 was used as sweep gas; however, the carbon yield of liquid products closely matched that of the previous experiment using N2 sweep gas (-70%), as shown in Table 1.

[0104] Table 1: Comparison of ketonization in N2 and CO2

[0105] The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase “consisting essentially of’ will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase “consisting of’ excludes any element not specified.

[0106] The present disclosure is not to be limited in terms of the particular embodiments described in this application. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and compositions within the scope of the disclosure, in addition to those enumerated herein, will be apparent130647-0244 to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions, or biological systems, which can of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0107] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0108] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member.

[0109] All publications, patent applications, issued patents, and other documents referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure.

[0110] Embodiment A. A method for producing ketones, the method comprising:contacting, in a first reactor, a feedstock comprising fatty acids with a first ketonization catalyst to produce a first product comprising ketones, unreacted fatty acids, carbon dioxide, and water;contacting the first product with a molecular sieve to absorb at least a portion of the water to produce a water-reduced first product; andcontacting, in a second reactor, the water-reduced first product with a second ketonization catalyst to produce a second product comprising ketones, unreacted fatty acids, carbon dioxide and water, wherein the second product has a ketone concentration that is higher than a ketone concentration of the first product.130647-0244

[0111] Embodiment B. The method of Embodiment A, wherein at least one of the first ketonization catalyst and the second ketonization catalyst comprises a metal oxide.

[0112] Embodiment C. The method of Embodiment B, wherein the metal oxide comprises an amphoteric metal oxide.

[0113] Embodiment D. The method of Embodiment C, wherein the amphoteric metal oxide comprises cerium oxide (CeO2), titanium dioxide (TiO2), manganese (IV) dioxide (Mn02), or zirconium oxide (ZrO2).

[0114] Embodiment E. The method of Embodiment A, wherein the fatty acids comprise C4-C9 fatty acids or wherein the ketones comprise C7-C17 ketones.

[0115] Embodiment F. The method of Embodiment A, wherein the first ketonization catalyst and the second ketonization catalyst are different.

[0116] Embodiment G. The method of Embodiment A further comprising:contacting the second product with a molecular sieve to produce a water-reduced second product;andcontacting, in a third reactor, the water-reduced second product with a third ketonization catalyst to produce a third product comprising ketones, unreacted fatty acids, carbon dioxide, and water,wherein the third product has a ketone concentration that is greater than the ketone concentration of the second product.

[0117] Embodiment H. The method of Embodiment A further comprising:starting with the second product, iteratively repeating steps comprising:contacting the product with a molecular sieve to produce a water-reduced product; andcontacting, in a reactor, the water-reduced product with a ketonization catalyst to convert at least a portion of unreacted fatty acids in the water-reduced product to ketones and to produce a subsequent product, until a yield of ketones in a product is greater than 98% of a theoretical maximum ketone yield; andcollecting the product having a yield of ketones greater than 98% of the theoretical maximum ketone yield.130647-0244

[0118] Embodiment I. The method of Embodiment A, wherein the contacting the fatty acids with the first ketonization catalyst and contacting the first products with a molecular sieve occurs in the same reactor or same equipment; orwherein contacting the first products with a molecular sieve and contacting the fatty acids with the second ketonization catalyst occurs in the same reactor or same equipment.

[0119] Embodiment J. A method for producing ketones, the method comprising:in a first reactor, contacting a feedstock comprising fatty acids with a first ketonization catalyst to produce a first product comprising ketones, unreacted fatty acids, carbon dioxide and water;contacting the first product with a water-permeable membrane to produce a water-reduced first product; andin a second reactor, contacting the water-reduced first product with a second ketonization catalyst to form a second product comprising ketones, unreacted fatty acids, carbon dioxide and water,wherein a ketone concentration of the second product is greater than a ketone concentration of the first product.

[0120] Embodiment K. The method of Embodiment J, wherein at least one of the first ketonization catalyst comprise metal oxides or amphoteric metal oxides.

[0121] Embodiment L. The method of Embodiment K, wherein the amphoteric metal oxides comprise cerium oxide (CeO2), titanium dioxide (TiO2), manganese (IV) dioxide (Mn02), or zirconium oxide (ZrO2).

[0122] Embodiment M. The method of Embodiment J, wherein the fatty acids comprise C4-C9 fatty acids; or wherein the ketones comprise C7-C17 ketones.

[0123] Embodiment N. The method of Embodiment J further comprising:contacting the second product with a water-permeable membrane to produce a water-reduced second product; andin a third reactor, contacting the water-reduced second product with a third ketonization catalyst to produce a third product comprising ketones, unreacted fatty acids, and water.

[0124] Embodiment O. The method of Embodiment J further comprising:130647-0244 starting with the second product, iteratively repeating steps comprising:contacting the product with a water-permeable membrane system to produce a water-reduced product; andcontacting, in a reactor, the water-reduced product with a ketonization catalyst to convert at least a portion of unreacted fatty acids in the water-reduced product to ketones and to produce a subsequent product, until a yield of ketones in a product is greater than 98% of a theoretical maximum ketone yield; andcollecting the product having a yield of ketones greater than 98% of the theoretical maximum ketone yield.

[0125] Embodiment P. The method of Embodiment J, wherein the contacting the fatty acids with the first ketonization catalyst and contacting the first products with a water-permeable membrane system occurs in the same reactor or equipment; orwherein contacting the first products with a water-permeable membrane system and contacting the fatty acids with the second ketonization catalyst occurs in the same reactor or equipment.

[0126] Embodiment Q. A method for producing ketones, the method comprising: contacting fatty acids with a ketonization catalyst located inside or outside of water-permeable membranes to form ketones, water, and carbon dioxide such that the water-permeable membranes separate at least a portion of the water from the ketones as the water is formed.

[0127] Embodiment R. The method of Embodiment Q, wherein the ketonization catalyst are metal oxides or amphoteric metal oxides.

[0128] Embodiment S. The method of Embodiment R, wherein the amphoteric metal oxides comprise cerium oxide (CeO2), titanium dioxide (TiO2), manganese (IV) dioxide (Mn02), or zirconium oxide (ZrO2).

[0129] Embodiment T. The method of Embodiment Q, wherein the fatty acids comprise C4-C9 fatty acids, or wherein the ketones comprise C7-C17 ketones.

[0130] Embodiment U. A method for producing ketones, the method comprising:contacting fatty acids with a water-permeable membrane, the water-permeable membrane configured to provide ketonization catalytic activity at least one of an inside surface and an outside surface of the water-permeable membrane,130647-0244 wherein contacting the fatty acids with the water-permeable membrane produces ketones, water, and carbon dioxide, andwherein at least a portion of the water is separated from the ketones by the water-permeable membrane as the water is formed.

[0131] Embodiment V. The method of Embodiment U, wherein a ketonization catalytic activity of the water-permeable membrane is provided by the presence of one or more metal oxides or amphoteric metal oxides.

[0132] Embodiment W. The method of Embodiment U, wherein the fatty acids comprise C4-C9 fatty acids, or wherein the ketones comprise C7-C17 ketones.

[0133] Embodiment X. The method of any one of Embodiments A, J, Q, or U, wherein the ketonization is performed at temperatures ranging from about 200 °C to about 500 °C, and preferably from about 300 °C to about 450 °C.

[0134] Embodiment Y. The method of any one of claims Embodiments A, J, Q, or U, wherein the ketonization reaction is aided by using a sweep or carrier gas.

[0135] Embodiment Z. A method for producing ketones, the method comprising: contacting, in a reactor under vacuum or a series of reactors under vacuum, a feedstock comprising fatty acids with a ketonization catalyst to produce a product comprising ketones, carbon dioxide, and water.

[0136] Embodiments AA. The method of Embodiment Z, wherein the ketonization catalyst comprises a metal oxide.

[0137] Embodiments BB. The method of Embodiment AA, wherein the metal oxide comprises an amphoteric metal oxide.

[0138] Embodiments CC. The method of Embodiment BB, wherein the amphoteric metal oxide comprises cerium oxide (CeO2), titanium dioxide (TiO2), manganese (IV) dioxide (Mn02), magnesium oxide (MgO) or zirconium oxide (ZrO2).

[0139] Embodiments DD. The method of Embodiment AA, wherein the fatty acids comprise C4-C9 fatty acids or wherein the ketones comprise C7-C17 ketones.

[0140] References:

[0141] Ahn, J.H.; Jung, K.H., Lim, E.S.; Kim, S.M.; Han, S O.; Um, Y. “Recent advances in microbial production of medium chain fatty acid from renewable carbon resources: A comprehensive review,” Bioresource Technology 381 (2023) 129147.130647-0244

[0142] Atasoy, M., Owusu-Agyeman, I., Plaza, E., Cetecioglu, Z. “Bio-based volatile fatty acid production and recovery from waste streams: Current status and future challenges,” Bioresource Technology 268 (2018) 773-786.

[0143] de la Iglesia, O., Reyes Mallada , M., Menendez, J.C., “Continuous zeolite membrane reactor for esterification of ethanol and acetic acid,” Chemical Engineering Journal 131 (2007) 35-39.

[0144] Delarmelina, M., Deshmukh, G., Goguet, A., Catlow, C. R. A., Manyar, H. “Role of sulfation of zirconia catalysts in vapor phase ketonization of acetic acid,” J. Phys. Chem. C, 125, (2021) 27578-27595.

[0145] Ding, S., Zhao, J., Yu, Q. “Effect of Zirconia Polymorph on Vapor-Phase Ketonization of Propionic Acid,” Catalysts 2019, 9 (2019) 768; doi:10.3390 / catal9090768.

[0146] Fufachev, E.V., Weckhuysen, B.M., Bruijnincx, P.C.A. “Toward catalytic ketonization of volatile fatty acids extracted from fermented wastewater by adsorption,” ACS Sustainable Chem. Eng.2020, 8, (2020) 11292-11298.

[0147] Gao, X., Deng, S., Kawi, S. “Zeolite -based catalytic membrane reactors for thermo-catalytic conversion of CO2,” iScience 25 (2022) 105343; doi: 10.1016 / j.isci. 2022.105343.

[0148] Glihski, M., Kijehski, J., Jakubowski, A. “Ketones from monocarboxylic acids: Catalytic ketonization over oxide systems,” Applied Catalysis A: General 128 (1995) 209-217.

[0149] Huq, N.A., Hafenstine, G.R., Huoa, X., Nguyen, H., Tifft, S.M., Conklin, D.R., Stuck, D., Stunkel, J., Yang, Z., Heyne, J.S., Wiatrowski, M.R., Zhang, Y., Tao, L., Zhu, J., McEnally, C.S., Christensen, E.D., Hays, C., Van Allsburg, K.M., Unocic, K.A., Meyer III, H.M., Abdullah, Z., Vardon, D.R. “Toward net-zero sustainable aviation fuel with wet waste-derived volatile fatty acids,” PNAS 118:13 (2021) e2023008118.

[0150] Kanervo, J., Toppinen, S., Nurmi, P. “Method for producing ketones for fuel and oil applications,” U.S. Patent 10,968,398.

[0151] Miller, J.H., Hafenstine, G.R., Nguyen, H.H., Vardon, D.R., “Kinetics and reactor design principles of volatile fatty acid ketonization for sustainable aviation fuel production,” Ind. Eng. Chem. Res. 2022, 61 (2022) 2997-3010.

[0152] Neushul, P., “Seaweed for war: California’s world war I kelp industry,” Technol. Cult.30, 561 (1989). https: / / doi.org / 10.2307 / 3105951.130647-0244

[0153] Pham, T. N., Sooknoi, T., Crossley, S. P., Resasco, D. E. “Ketonization of carboxylic acids: mechanisms, catalysts, and implications for biomass conversion,” ACS Catal. 3 (2013)2456-2473.

[0154] Ross, M.K. & Granda, C.B. “System and Process for Obtaining Products from Biomass,” U.S. Patent 10,662,447.

[0155] Squibb, E. R. "Improvement in the Manufacture of Acetone.1". Journal of the American Chemical Society. 17 (3) (1895) 187-201.

[0156] Yue, W., Li, Y., Wei, W., Jiang, J., Caro, J., Huang, A. “Highly Selective CO2 Conversion to Methanol in a Bifunctional Zeolite Catalytic Membrane Reactor,” Angew. Chem. 133 (2021) 18437 - 18442.

[0157] Zhang, S., Jiang, B., Tong, M., Yang, Y., Liao, Z., Huang, Z., Sun, J., Wang, J., Yang, Y. “Efficient Cu / CcCf for ketonization of carboxylic acids with synergistic interactions,” Ind. Eng. Chem. Res., 62, (2023) 20667-20676.

[0158] Other embodiments are set forth in the following claims:

Claims

130647-0244 CLAIMS WHAT IS CLAIMED IS:

1. A method for producing ketones, the method comprising:contacting, in a first reactor, a feedstock comprising fatty acids with a first ketonization catalyst to produce a first product comprising ketones, unreacted fatty acids, carbon dioxide, and water;contacting the first product with a molecular sieve to absorb at least a portion of the water to produce a water-reduced first product; andcontacting, in a second reactor, the water-reduced first product with a second ketonization catalyst to produce a second product comprising ketones, unreacted fatty acids, carbon dioxide and water, wherein the second product has a ketone concentration that is higher than a ketone concentration of the first product.

2. The method of claim 1, wherein at least one of the first ketonization catalyst and the second ketonization catalyst comprises a metal oxide.

3. The method of claim 2, wherein the metal oxide comprises an amphoteric metal oxide.

4. The method of claim 3, wherein the amphoteric metal oxide comprises cerium oxide (CcCT). titanium dioxide (TiO?). manganese (IV) dioxide (MnO?). or zirconium oxide (ZrO?).

5. The method of claim 1, wherein the fatty acids comprise C4-C9 fatty acids or wherein the ketones comprise C7-C17 ketones.

6. The method of claim 1, wherein the first ketonization catalyst and the second ketonization catalyst are different.

7. The method of claim 1 further comprising:contacting the second product with a molecular sieve to produce a water-reduced second product;andcontacting, in a third reactor, the water-reduced second product with a third ketonization catalyst to produce a third product comprising ketones, unreacted fatty acids, carbon dioxide, and water,wherein the third product has a ketone concentration that is greater than the ketone concentration of the second product.

8. The method of claim 1 further comprising:starting with the second product, iteratively repeating steps comprising:contacting the product with a molecular sieve to produce a water-reduced product; and130647-0244 contacting, in a reactor, the water-reduced product with a ketonization catalyst to convert at least a portion of unreacted fatty acids in the water-reduced product to ketones and to produce a subsequent product, until a yield of ketones in a product is greater than 98% of a theoretical maximum ketone yield; andcollecting the product having a yield of ketones greater than 98% of the theoretical maximum ketone yield.

9. The method of claim 1, wherein the contacting the fatty acids with the first ketonization catalyst and contacting the first products with a molecular sieve occurs in the same reactor or same equipment; orwherein contacting the first products with a molecular sieve and contacting the fatty acids with the second ketonization catalyst occurs in the same reactor or same equipment.

10. A method for producing ketones, the method comprising:in a first reactor, contacting a feedstock comprising fatty acids with a first ketonization catalyst to produce a first product comprising ketones, unreacted fatty acids, carbon dioxide and water;contacting the first product with a water-permeable membrane to produce a water-reduced first product; andin a second reactor, contacting the water-reduced first product with a second ketonization catalyst to form a second product comprising ketones, unreacted fatty acids, carbon dioxide and water,wherein a ketone concentration of the second product is greater than a ketone concentration of the first product. .

11. The method of claim 10, wherein at least one of the first ketonization catalyst comprise metal oxides or amphoteric metal oxides.

12. The method of claim 11, wherein the amphoteric metal oxides comprise cerium oxide (CcCT).titanium dioxide (TiO?). manganese (IV) dioxide (MnO?). or zirconium oxide (ZrO?).

13. The method of claim 10, wherein the fatty acids comprise C4-C9 fatty acids; or wherein the ketones comprise C7-C17 ketones.

14. The method of claim 10 further comprising:contacting the second product with a water-permeable membrane to produce a water-reduced second product; andin a third reactor, contacting the water-reduced second product with a third ketonization catalyst to produce a third product comprising ketones, unreacted fatty acids, and water.130647-0244 15. The method of claim 10 further comprising:starting with the second product, iteratively repeating steps comprising:contacting the product with a water-permeable membrane system to produce a water- reduced product; andcontacting, in a reactor, the water-reduced product with a ketonization catalyst to convert at least a portion of unreacted fatty acids in the water-reduced product to ketones and to produce a subsequent product, until a yield of ketones in a product is greater than 98% of a theoretical maximum ketone yield; andcollecting the product having a yield of ketones greater than 98% of the theoretical maximum ketone yield.

16. The method of claims 10, wherein the contacting the fatty acids with the first ketonization catalyst and contacting the first products with a water-permeable membrane system occurs in the same reactor or equipment; orwherein contacting the first products with a water-permeable membrane system and contacting the fatty acids with the second ketonization catalyst occurs in the same reactor or equipment.

17. A method for producing ketones, the method comprising:contacting fatty acids with a ketonization catalyst located inside or outside of water-permeable membranes to form ketones, water, and carbon dioxide such that the water-permeable membranes separate at least a portion of the water from the ketones as the water is formed.

18. The method of claim 16, wherein the ketonization catalyst are metal oxides or amphoteric metal oxides.

19. The method of claim 18, wherein the amphoteric metal oxides comprise cerium oxide (CcCT).titanium dioxide (TiO?). manganese (IV) dioxide (MnO?). or zirconium oxide (ZrO?).

20. The method of claim 16, wherein the fatty acids comprise C4-C9 fatty acids, or wherein the ketones comprise C7-C17 ketones.

21. A method for producing ketones, the method comprising:contacting fatty acids with a water-permeable membrane, the water-permeable membrane configured to provide ketonization catalytic activity at least one of an inside surface and an outside surface of the water-permeable membrane,wherein contacting the fatty acids with the water-permeable membrane produces ketones, water, and carbon dioxide, and130647-0244 wherein at least a portion of the water is separated from the ketones by the water-permeable membrane as the water is formed.

22. The method of claim 21, wherein a ketonization catalytic activity of the water-permeable membrane is provided by the presence of one or more metal oxides or amphoteric metal oxides.

23. The method of claim 21, wherein the fatty acids comprise C4-C9 fatty acids, or wherein the ketones comprise C7-C17 ketones.

24. The method of any one of claims 1, 10, 17, or 21, wherein the ketonization is performed at temperatures ranging from about 200 °C to about 500 °C, and preferably from about 300 °C to about 450 °C.

25. The method of any one of claims 1, 10, 17, or 21, wherein the ketonization reaction is aided by using a sweep or carrier gas.

26. A method for producing ketones, the method comprising:contacting, in a reactor under vacuum or a series of reactors under vacuum, a feedstock comprising fatty acids with a ketonization catalyst to produce a product comprising ketones, carbon dioxide, and water.

27. The method of claim 26, wherein the ketonization catalyst comprises a metal oxide.

28. The method of claim 27, wherein the metal oxide comprises an amphoteric metal oxide.

29. The method of claim 28, wherein the amphoteric metal oxide comprises cerium oxide (CcO?). titanium dioxide (TiO?). manganese (IV) dioxide (MnO?). magnesium oxide (MgO) or zirconium oxide (ZrCh).

30. The method of claim 26, wherein the fatty acids comprise C4-C9 fatty acids or wherein the ketones comprise C7-C17 ketones.

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