WO2024081921A2

WO2024081921A2 - Selective hydrogenation of aldehydes and ketones in ester solutions over copper-based catalysts & a system and method for ethyl acetate production

Info

Publication number: WO2024081921A2
Application number: PCT/US2023/076898
Authority: WO
Inventors: Sagar B. Gadewar; Brian Christopher VICENTE; Amit HASABNIS
Original assignee: Viridis Chemical, Llc
Priority date: 2022-10-13
Filing date: 2023-10-13
Publication date: 2024-04-18

Abstract

A method of selectively hydrogenating ketones or aldehydes includes contacting a reaction mixture with a hydrogenation catalyst under hydrogenation reaction conditions, and hydrogenating at least a portion of the at least one ketone or aldehyde to form an alcohol. The reaction mixture comprises hydrogen, at least one ester, and at least one ketone or aldehyde, and the hydrogenation catalyst comprises copper or copper oxide. Less than 5% by weight of the ester is converted to one or more reaction products.

Description

SELECTIVE HYDROGENATION OF ALDEHYDES AND KETONES IN ESTER SOLUTIONS OVER COPPER-BASED CATALYSTS & A SYSTEM AND METHOD FOR ETHYL ACETATE PRODUCTION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63/379,435 filed on October 13, 2022 and entitled, “SELECTIVE HYDROGENATION OF ALDEHYDES AND KETONES IN ESTER SOLUTIONS OVER COPPER-BASED CATALYSTS & A SYSTEM AND METHOD FOR ETHYL ACETATE PRODUCTION,” which is incorporated herein in its entirety for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

|0002| Not applicable.

BACKGROUND

[0003] Esters can be produced from several different reactions. The most common method for making some esters such as ethyl acetate is the esterification of acetic acid and ethanol. This reaction requires two raw material supplied with the associated storage or production facilities. In locations without a sufficient supply of reliable, inexpensive acetic acid, this process may not be economically viable. Further, the process can result in impurities that are hard to separate, which can impede the production of high purity esters.

SUMMARY

[0004] In some embodiments, a method of selectively hydrogenating ketones or aldehydes comprises contacting a reaction mixture with a hydrogenation catalyst under hydrogenation reaction conditions, and hydrogenating at least a portion of the at least one ketone or aldehyde to form an alcohol. The reaction mixture comprises hydrogen, at least one ester, and at least one ketone or aldehyde, and the hydrogenation catalyst comprises copper or copper oxide. Less than 5% by weight of the ester is converted to one or more reaction products.

[0005] In some embodiments, a method of producing ethyl acetate comprises feeding a feed stream comprising ethanol to a reactor system, contacting the feed stream with a dehydrogenation catalyst in at least one of the distillation column or the at least one side reactor, dehydrogenating ethanol over the dehydrogenation catalyst to produce ethyl acetate and at least one side product, contacting the ethyl acetate and the at least one side product with a hydrogenation catalyst in at least one of the distillation column or the at least one side reactor, hydrogenating at least a portion of the at least one side product, removing at least a portion of the ethyl acetate in a bottoms product stream, and removing hydrogen as an top product stream. The reactor system comprises a distillation column and at least one side reactor in fluid communication with the distillation column.

[0006] In some embodiments, a reactor system for producing ethyl acetate comprises: a distillation column, a first side reactor comprising a first inlet and a first outlet, and a second side reactor comprising a second inlet and a second outlet. The first inlet is in fluid communication with the distillation column, and the first side reactor comprises a dehydrogenation catalyst. The second inlet is in fluid communication with the first outlet of the first side reactor, and the second outlet is in fluid communication with the distillation column. The second side reactor comprises a hydrogenation catalyst, and the distillation column comprises an overhead product removal passage and a bottoms product ethyl acetate removal passage.

|0007| These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description.

[0009] Figure 1 shows a simplified schematic of a reactive distillation system according to an embodiment.

[0010] Figure 2 shows another simplified schematic of a reactive distillation system according to an embodiment.

DETAILED DESCRIPTION

[0011] Mixtures of esters with ketone and/or aldehyde impurities often cannot be purified by traditional distillation due to the presence of azeotropes. Converting the aldehyde or ketone into the corresponding alcohol via selective hydrogenation may remove such azeotropes and allow for purification of the ester from the alcohol(s) by distillation. However, esters can also be converted into alcohols through a hydrogenation reaction. Therefore, to use hydrogenation followed by distillation to purify an ester with aldehyde or ketone impurities, the catalyst must selectively perform the hydrogenation of the aldehydes and ketones over hydrogenation of the ester to its corresponding alcohols.

[0012] A mixture of esters with ketone and/or aldehyde impurities can occur in the production of ethyl acetate via dehydrogenation of ethanol, where one of the byproducts includes methyl ethyl ketone (MEK). MEK is difficult to remove from ethyl acetate via traditional distillation techniques due to the presence of a MEK- ethyl acetate azeotrope. One of the techniques for purifying ethyl acetate containing MEK is to selectively hydrogenate the MEK to 2-butanol, preferably without hydrogenating the ethyl acetate back into ethanol. Once the MEK is converted to 2-butanol, traditional distillation techniques can be used to purify the ethyl acetate.

[0013] Catalysts that can be used for this process include Ru, Pt, Pd, and Ni supported on high surface area support such as silica, alumina, or activated carbon. While the supported Pt-group metals are highly active and selective for this reaction, they suffer from high cost of materials to prepare, and due to the low metal loading (typically between 0.5 - 5.0 wt%) can deactivate quickly if the MEK/ethyl acetate stream contains any catalyst poisons. Past results have shown that some Ni-based catalysts have lower activity than the precious metal catalysts, thereby requiring much larger reactor and catalyst volumes to achieve the desired chemical conversion.

[0014] Although Cu-based catalysts are known to be effective for the hydrogenation of aldehydes and ketones to alcohols, their use in systems that also contain esters has been limited due to copper’s ability to convert esters into alcohols in the presence of hydrogen (i.e. converting ethyl acetate and hydrogen into ethanol). As described herein, Cu-based catalysts can be used to selectively hydrogenate byproducts including aldehydes and ketones with a limited conversion of the esters into alcohols. Several different Cu-based catalysts have been prepared and tested for the selective hydrogenation of a solution of methyl ethyl ketone (MEK) and ethyl acetate. These copper-based catalysts performed the desired aldehyde and ketone hydrogenation selectively with high conversion with a limited conversion of the ethyl acetate.

[0015] The use of copper-based and/or nickel-based hydrogenation catalysts provides a number of advantages. For example, the use of copper-based hydrogenation catalysts can reduce or altogether eliminate the need for precious metals and allow for higher metal loadings that may make the catalyst less prone to deactivation. The copper catalysts also have similar reactivity to the supported Pt-group metals, allowing for smaller reactor sizes than are necessary with the Ni- based catalysts alone. Although copper can be used as a catalyst for the hydrogenation of ethyl acetate to form an alcohol, under the MEK hydrogenation reaction conditions, very little of the ethyl acetate is converted back into ethanol.

[0016] In an embodiment, the hydrogenation catalyst can be used to selectively hydrogenate ketones and/or aldehydes in the presence of an ester. The hydrogenation reaction can generally be carried out with the mixture being contacted with the hydrogenation catalyst in the presence of hydrogen. At least a portion of the ketones and/or aldehydes can be converted into non-ketone and/or non-aldehyde reaction products.

[0017] The hydrogenation catalyst described herein generally comprises copper or copper oxide. In some embodiments, the hydrogenation catalyst can consist essentially of copper or copper oxide, where the copper or copper oxide can be disposed on any of the supports described herein. Additional metals can also be present in some embodiments. For example, the catalyst can also comprise zirconium, zirconium oxide, aluminum, aluminum oxide, nickel, and/or nickel oxide. In some embodiments, the hydrogenation catalyst can include, but is not limited to, Re, Ni, Fe, Co, Ru, Pd, Rh, Pt, Os, Ir, oxides thereof, and alloys or any combination thereof, either alone or with promoters such as W, Mo, Au, Ag, Cr, Zn, Mn, Sn, B, P, Bi, oxides thereof, and alloys or any combination thereof. In some embodiments, the hydrogenation catalyst may not comprise any Pt-group metals.

[0018] In certain embodiments, the hydrogenation catalyst may include a catalyst support that can stabilize and support the catalyst. The type of catalyst support used depends on the chosen catalyst and the reaction conditions. Suitable supports may include, but are not limited to, carbon, silica, silica-alumina, alumina, magnesia, zirconia, titania, ceria, vanadia, nitride, boron nitride, heteropolyacids, hydroxyapatite, zinc oxide, chromia, zeolites, carbon nanotubes, carbon fullerenes, and any combination thereof.

[0019] The copper loading in the hydrogenation catalyst can vary depending on the form of the copper and the type of preparation of the catalyst. In some embodiments, the copper weight loading (i.e., weight percentage) in the hydrogenation catalyst can be between about 0.5% and about 90%, between about 10% and about 80 %, between about 20 % and about 65%, between about 30 % and about 60%, or about 40% and about 50%.

[0020] In some embodiments, the hydrogenation catalyst can have a zirconium or zirconium oxide weight loading between about 0.5% and about 20%, or between about 5% and about 15%.

|0021| In some embodiments, the hydrogenation catalyst can have an aluminum or aluminum oxide weight loading between about 0.5% and about 40%, between about 3% and about 30%, or between about 3% and between about 25%. [0022] In some embodiments, the hydrogenation catalyst can have nickel or nickel oxide weight loading between about 30% and about 60%, and can optionally contain silica in an amount of between 10% to about 30% with the balance being alumina, all on a weight basis. In some aspects such as this catalyst, the catalyst may not contain copper.

[0023] The copper or nickel based hydrogenation catalyst can be prepared using any suitable methods. In an embodiment, the copper or nickel based catalysts for the selective hydrogenation of aldehydes and ketones in ester solutions can be prepared either via impregnation of a catalyst support or via coprecipitation with other metals and/or metal oxides.

[0024] In an embodiment, supported copper catalysts can be prepared via incipient wetness impregnation of a variety of supports. A typical preparation involves dissolving about 4 g of Cu(NO3)2*2.5H2O in 30 mL of de-ionized water, which is then added to 30 g of the appropriate oxide support and stirred until well mixed. The impregnated support can then be dried in air at 1 10 °C, followed by calcination in air at 450 °C. The amount of Cu(NO3)2’2.5H2O can be adjusted to achieve a desired final Cu weight loading. Enough water should be used to wet the entire oxide support. Typical Cu loadings are between 0.5 and 20 wt%. Potential supports include alumina, silica, zirconia, zinc oxide, magnesia, and silica-alumina. Typical copper loadings can range from 0.5 wt% to 30 wt%. Other copper salts can be used in place of the Cu(NO3)2’2.5H2O. [0025] In an embodiment, mixed-metal oxide catalysts can be prepared via coprecipitation from nitrate solutions. In a typical co-precipitation synthesis, a measured amount of the appropriate metal nitrates (Cu, Zn, Zr, Al, Cr, Fe, Ni, Ba) are dissolved in deionized water (total metal concentration ranges from 0.5 - 3 M). The metal nitrate solution is then precipitated by dropwise addition to a stirred, equal volume of 4 M aqueous NaOH at room temperature. After addition of all the metal nitrate solution, the suspension is stirred for 12 - 24 hours to ensure complete precipitation of the metal oxides. The precipitated solid is then filtered and washed with excess deionized water. The solids are then dried overnight at 110 °C, followed by calcination at 220 - 500 °C. Catalysts prepared in this manner have CuO loadings between 40 - 80 wt%. The loadings of other metal oxides range from 2 - 40 wt%.

[0026] A catalyst binder can be added to the mixed-metal oxide to impart additional mechanical strength. The metal oxide catalyst is ground to a fine powder and then stirred into a colloidal suspension of silica or alumina in water. The resulting suspension is stirred while heating at 80-130 °C to dryness. The resulting solid can then be either extruded or pressed, ground, and sieved to appropriate particle sizes. An alternative is to add the colloidal silica or alumina suspension to the 4 M NaOH precipitation solution prior to addition of the metal nitrate solution. In some aspects, the resulting silica and/or alumina can form between about 5 wt.% to about 40 wt.%, or between about 10 wt.% to about 30 wt.% of the final catalyst composition.

[0027] In the preparation method, other metal salts, including acetates and carbonates, can be used in place of the nitrates, and other basic salts such as sodium bicarbonate, potassium hydroxide, or potassium bicarbonate may be used in place of the sodium hydroxide. The mixing of the metal nitrate solution and the basic solution may be done so that both are added dropwise into a receiving vessel. The addition of the basic solution may be adjusted to keep the liquid in the receiving vessel at a desired pH.

[0028] Suitable hydrogenation catalyst can include catalysts containing copper. For example, catalysts comprising CuO/ZnO/AlsCh (e.g,. a low temperature water gas shift catalysts), CuO/Cr2Os and CuO/Cr2Os/BaO (dehydrogenation catalysts), and 13wt% CuO on AI2O3 (commonly used as an oxygen scavenger) may all be potentially used as hydrogenation catalysts.

[0029] In some embodiments, a nickel catalyst can be used. Such a catalyst including a support can include about 30 to about 60 wt % of nickel, about 10 to about 30 wt % of silica, with the balance being alumina. In some aspect, the catalysts may not contain copper, or may only contain minor amounts of copper.

[0030] In some embodiments, a catalyst can have metal oxides of copper oxide (CuO), zirconium oxide (ZrO2), and chromium oxide (Cr20s) on an alumina (AI2O3) support. The catalyst can include any suitable amount of metal oxides, such as a metal loading of, independently, about 5 wt % to about 95 wt %, about 10 wt % to about 90 wt %, about 15 wt % to about 85 wt %, or about 20 wt % to about 80 wt % of copper or copper oxide. The metal loading, independently, of ZrOs can be about no more than about 40 wt %, no more than about 35 wt %, no more than about 30 wt %, or no more than about 25 wt %, or about 10 wt % to about 25 wt %. The metal loading, independently, of CtoOs can be about no more than about 25 wt %, no more than about 20 wt %, or no more than about 15 wt %, or about 10 wt % to about 15 wt %. The metal loading weight percent is based on the total amount of metal loaded onto the catalyst. The amount of AI2O3 can range from about 1 wt % to about 99 wt %, about 2 wt % to about 98 wt %, about 3 wt % to about 97 wt %, about 5 wt % to about 95 wt %, or about 7 wt % to about 93 wt %, based on the total weight of the catalyst.

[0031] As described above, the hydrogenation catalyst can be used to selectively react one or more ketones and/or aldehydes as compared to an ester. In this process, the reaction mixture may comprise between about 10% and about 99.5% of one or more esters. In the example of the production of ethyl acetate, the ester may comprise the ethyl acetate itself. Other esters may be present in some embodiments, with or without ethyl acetate. For example, the ester may comprise butyl acetate, ethyl butyrate, methyl acetate, isopropyl acetate, or butyl butyrate

[0032] The remainder of the reaction mixture composition can comprise one or more ketones, one or more aldehydes, and/or one or more additional components. Various ketones and/or aldehydes may be present in the reaction mixture such as MEK, n-butyraldehyde, acetaldehyde, crotonaldehyde, or any combination thereof. Additional components can be present and may not substantially affect the selectivity of the hydrogenation reaction. In some embodiments, the reaction mixture may comprise between about 0.001 % and about 20%, or between about 0.01 % and about 10% of one or more ketones and/or aldehydes.

[0033] The reaction mixture may also comprise hydrogen, or hydrogen can be introduced directly into the reactor in the presence of the hydrogenation catalyst. The amount of hydrogen present may be sufficient to hydrogenate a desired portion of the ketones and/or aldehydes (e.g., some or all of the ketones and/or aldehydes). Due to mass transport and reaction equilibrium limitations, a molar excess of hydrogen can be present within the reactor in order to hydrogenate the desired amount of the ketones and/or aldehydes. In an embodiment, a ratio of the amount of hydrogen in the reaction mixture to the amount of the ketones and/or aldehydes can be between about 1 :1 and about 1000:1 on a molar basis.

|0034| The reaction mixture can be contacted with the hydrogenation catalyst in the presence of the hydrogen at reaction conditions. The hydrogenation reaction can be carried out at any suitable conditions of temperature, pressure, and flow rate to effect the hydrogenation reaction. In an embodiment, the hydrogenation reaction may be carried out between about 70 °C and about 300 °C or between about 80 °C and about 150 °C. The reaction pressure may be between about 1 and about 50 atm. In some embodiments, the reaction pressure may be sufficient to maintain the ester and the ketones and/or aldehydes in the liquid phase during the reaction, though vapor phase reactions can also be used. The conditions within the reactor can be controlled to maintain the reactants in a desired phase (e.g., in a vapor phase and/or al liquid phase).

[0035] The reaction mixture and hydrogen flow rate through the reactor can vary and the liquid hourly space velocity may range from about 0.25 hr¹ to about 10 hr¹ or between about 0.5 hr¹ to about 6 hr^-1. Any suitable reactor design can be used including a plug flow reactor, a packed bed reactor, a fluidized bed reactor, or the like.

[0036] The hydrogenation reaction may result in the conversion of the ketones and/or aldehydes into non-ketone and/or non-aldehyde components. For example, the hydrogenation of MEK may result in the production of 2-butanol, which is easier to separate from the ester than MEK using distillation. In some embodiments, the conversion of the ketones and/or aldehydes may be complete or substantially complete. In some embodiments, the conversion of the ketones and/or aldehydes to non-ketone and/or non-aldehyde components may have a conversion rate of at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or at least about 99.8%.

[0037] The hydrogenation reaction using the copper-based and/or nickel-based hydrogenation catalyst may result in some amount of the ester being converted into a non-ester product such as an alcohol. Under the hydrogenation conditions described herein, the amount of the ester converted to a non-ester product may be less than about 5%, less than about 4%, less than about 3%, less than about 2%, less than about 1 %, less than about 0.5%, or less than about 0.3% by weight of the ester present in the initial reaction mixture.

[0038] The hydrogenation catalyst may advantageously selectively convert the ketones and/or aldehydes in the reaction mixture relative to the ester or esters. In an embodiment, a ratio of: 1 ) the total conversion of the ketones and/or aldehydes to non-ketone and/or non-aldehyde component to 2) the total conversion of the ester or esters to non-ester components can range from about 20: 1 to about 400: 1 , or between about 40: 1 to about 300: 1 or between about 50: 1 to about 200: 1 .

[0039] In the production of ethyl acetate, the hydrogenation reaction can be used to hydrogenate MEK in a mixture of ethyl acetate. Additional ketones and/or aldehydes such as n-butyraldehyde, acetaldehyde, and/or crotonaldehyde may also be present in the mixture. The hydrogenation reaction can be carried out using the hydrogenation catalyst to reduce the concentration of the ketones and/or aldehydes below the azeotropic concentration between MEK and ethyl acetate. The product mixture can then be further separated to remove a portion of the hydrogenation products and/or any remaining ketones and/or aldehydes. [0040] In some embodiments, the hydrogenation catalyst described herein can be incorporated into an ethyl acetate production process. In general, the production of ethyl acetate can proceed through the use of a system such as a reactive distillation system in which ethanol may be the sole or primary component of the feed. As used herein, the term “reactive distillation” refers to the integration of a separation process with a chemical reaction. As advantages of this integration, chemical equilibrium limitations may be overcome, higher selectivities may be achieved, the heat of reaction may be used in situ for distillation, auxiliary solvents may be avoided, and/or azeotropic and/or closely boiling mixtures may be more easily separated. Increased process efficiency and reduction in overall capital costs may result from the use of this approach. As described in more detail herein, the use of a reactive distillation system may not necessarily carry out the chemical reaction within the separation process (e.g., the distillation column), though the reaction may be integrated with the separator in order to obtain the advantages of an integrated, overall process. For example, one or more side reactors that receive a feed from a distillation column and return the product to the distillation column and/or a reactor that receives a reactant stream from one or more recycle or separated streams from a separation process and returns a product stream to a separator can be used within the system.

[0041] In some embodiments, the ethanol feed used for the production of ethyl acetate can be used in conjunction with a separate, second feed of hydrogen. Reference to a “single feed” to a reaction system means that a component of the system has only one chemical feed stream supplying intended reactant(s) to the system. Nonetheless, such a single feed system may have multiple entry points for the reactant, or recycling feed streams where a part of the reactant can be fed to the system at different points. A “single ethanol feed” thus refers to a single feed stream, in which ethanol is the sole or at least the primary constituent. In contrast, the term “dual feed” in the context of a reaction system refers to two separate chemical feed streams. For example, in some of the present embodiments, dual feeds are an ethanol feed and a separate hydrogen feed. Thus, the present invention provides systems and methods for the production of ethyl acetate from ethanol which includes reacting ethanol over a suitable dehydrogenation and/or dimerization catalyst in one or more portions of the reactor system, thereby producing ethyl acetate and hydrogen.

[0042] In an embodiment, the reactive system is configured for the dehydrogenation of ethanol with the formation of ethyl acetate. The reaction is accomplished by passing the ethanol feed stream over a dehydrogenation catalyst under conditions where ethyl acetate is formed. The reaction mixture can then be separated in the distillation column so that hydrogen and ethyl acetate are withdrawn as top and bottoms products respectively. Such product draws drive the thermodynamics of the process toward the desired products. [0043] In an embodiment, separate reactors can be connected to a distillation column to increase the catalyst holdup for improved reactant conversion. The overall system can then form the reaction system. In some contexts, separate reactors that are only coupled to a distillation column can be referred to as “side reactors.” In the separate reactor embodiment, the reactor feed is withdrawn from the distillation column and the reactor effluent can be returned back to the same column, or the reactor feed can be withdrawn from the distillation column and the reactor effluent can be passed to a separate reactor for a further reaction, where the ultimate effluent is passed back to the distillation column. An adequate amount of catalyst may be arranged in a separate reactor where traditional reactor types and catalyst structures can be used. Also, the reaction conditions within the reactor such as temperature can be adjusted independently of those prevailing in the distillation column by appropriate heat exchange. When a subsequent reactor is used to receive the reactor effluent from the first reactor, the second reactor can be used to carry out a further ethyl acetate production reaction, or the second reactor can be used as a hydrogenation reactor to reduce the presence of any side products (e.g., ketones, aldehydes, etc.) in the ethyl acetate effluent from the first reactor. Each of the separate reactors can use different reaction conditions to improve the overall reaction performance.

[0044] Schematics for a reaction system 100, such as a reactive distillation system having two reactors 149 and 151 , is shown in Figure 1 . As shown in Figure 1 , the first reactor 149 and the second reactor 151 are disposed along the length of a distillation column 144. As shown, catalyst is only present in the reactors 149, 151. In some embodiments, some amount of a dehydration and/or hydrogenation catalyst can be present within the distillation column 144, but in other embodiments, the distillation column 144 may not contain any catalyst. In this embodiment, a feed stream 155 comprising ethanol can be combined with stream 156 drawn from the distillation column 144 to form a reaction mixture before entering the first reactor 149. The composition of stream 156 can vary and may depend on where the stream is withdrawn along the length of the distillation column 144. In general, stream 156 can comprise ethanol, some amount of ethyl acetate, and potentially some amount of byproducts. The stream 156 can be a vapor, a liquid, or a multi-phase fluid suitable for reacting in the first reactor 149. In an embodiment, the stream 156 may comprise or be a vapor stream such that a vapor phase reaction can take place within the first reactor 149. While shown as being combined with stream 156, both the feed stream 155 and stream 156 drawn from the distillation column 144 can be fed to the first reactor 149 as separate streams. Stream 155 and/or 156 can be dehydrated and/or or heated before entering reactor 149. For example, a dehydration unit and/or a heat exchanger can be present to heat stream 155 and/or stream 156 prior to the streams passing, individually or in combination, to the reactor 149. [0045] In some embodiments, the stream 156 can be the same as stream 160 such that the stream 156 is taken from downstream of the reflux tank 146 rather than directly from the distillation column 144. In general, the amount of ethanol can increase towards the top of the column, and the stream passing through the condenser 145 and the reflux tank 146 can be used as the feed to the reactor 149. When the stream 160 serves as a feed to the reactor 149, the stream 156 may not be present (but rather may be a part of the stream from the reflux tank 146), and the stream 160 can then be heated and/or dehydrated prior to passing to the reactor 149. In an embodiment in which the stream 160 is passed to the first reactor 149, the stream may pass to a heat exchanger and be vaporized prior to entering the first reactor 149.

[0046] The first reactor 149 can contain a dehydrogenation catalyst that can convert at least a portion of the ethanol in the reaction mixture into ethyl acetate. The ethyl acetate conversion reaction can be carried out at a pressure between about 1 and about 80 atm or between about 1 and about 50 atm. The temperature of the dehydrogenation reaction may be between about 100 °C to about 350 °C, alternatively about 150 °C to about 250 °C. The dehydrogenation catalyst can include any of the dehydrogenation catalysts described below.

|0047| While shown as a single reactor in Figure 1 , the first reactor 149 can optionally comprise one or more reactor vessels disposed in series or parallel, such that the first reactor 149 can comprise a reactor section. When a plurality of first reactors 149 is used, one or more heat exchangers can be used to maintain a temperature of the streams entering each reactor vessel. For example, the first reactor 149 can comprise a first reactor vessel followed by a heat exchanger that can adjust the temperature of the stream leaving the first reaction vessel to a desired temperature. The fluid passing out of the heat exchanger can then pass into a second reactor vessel. The dehydration catalyst within each vessel can be the same or different. This configuration may allow for a desired catalyst holdup along with control over the reaction conditions in each reaction vessel.

[0048] Within the first reactor 149 or reactor section, at least a portion of the ethanol in the reaction mixture can be converted to ethyl acetate and hydrogen. The resulting reactor effluent in line 157, which can be a multiphase fluid, can pass to the second reactor 151 , which can also represent a second reaction section. The second reactor 151 can be in fluid communication with the first reactor, for example, where the outlet of the first reactor 149 is coupled to the second reactor 151. In some embodiments, an optional heat exchanger 150 can be fluidly coupled between the first reactor 149 and the second reactor 151. The heat exchanger 150 may indirectly contact the effluent mixture with a heat exchange fluid to change the temperature of the effluent stream prior to the effluent passing through line 158 into the second reactor 151. The effluent stream can be heated or cooled as needed to obtain the appropriate temperature prior to the effluent stream passing to the second reactor 151 . [0049] Within the second reactor 151 , at least a portion of any products in the reactor effluent can be converted to separable components. As described in more detail above, the production of ethyl acetate may result in a minor amount (e.g., between about 0.01 % and about 10%) of products such as one or more ketones and/or aldehydes. For example methyl ethyl ketone (MEK) can be produced in the dehydrogenation reaction. In an embodiment, the second reactor 151 can contain a hydrogenation catalyst. In an embodiment, the hydrogenation catalyst can be any of the hydrogenation catalysts described herein (e.g., a copper-based hydrogenation catalyst). In some embodiments, the hydrogenation catalyst can comprise any of the hydrogenation catalysts described herein. The reactor effluent passing from the first reactor 149 can contact the hydrogenation catalyst in the presence of the hydrogen in the reactor effluent stream to hydrogenate at least a portion of the side products. In an embodiment, the conditions in the second reactor 151 may be different than the conditions in the first reactor 149. For example, the hydrogenation reaction can be carried out at a pressure between about 1 and about 80 atm or between about 1 and about 50 atm. The temperature of the dehydrogenation reaction may be between about 70 °C and about 300 °C or between about 80 °C and about 150 °C. In some embodiments, an additional amount of hydrogen can be introduced into the second reactor 151 , for example, as combined with stream 158 or as a direct feed into the second reactor 151 .

[0050] While shown as a single reactor in Figure 1 , the second reactor 151 can optionally comprise one or more reactor vessels disposed in series or parallel, such that the second reactor 151 can comprise a second reactor section. When a plurality of second reactors 151 is used, one or more heat exchangers can be used to maintain a temperature of the streams entering each reactor vessel. For example, the second reactor 151 can comprise a first reactor vessel followed by a heat exchanger that can adjust the temperature of the stream leaving the first reaction vessel to a desired temperature. The fluid passing out of the heat exchanger can then pass into a second reactor vessel. The hydration catalyst within each vessel can be the same or different. This configuration may allow for a desired catalyst holdup and reaction time along with control over the reaction conditions in each reaction vessel.

|00511 The outlet stream from the second reactor 151 can optionally be sent to a vapor-liquid flash 152 to remove non-condensables such as hydrogen as stream 159. If the vapor-liquid flash 152 is not present, the hydrogen may pass into the distillation column 144 along with the effluent from the second reactor 151. The hydrogen may then pass into the overhead stream and leave the system as part of the overhead product stream 166 from the reflux tank 146.

[0052] The liquid stream from the second reactor 151 and/or the vapor-liquid flash 152 can then pass to the distillation column 144 for distillation separation. The distillation column 144 allows the unconverted ethanol passing through the first reactor 149 to be separated from the product ethyl acetate. Within the distillation column 144, the distillate removed at the top of the column is passed through a partial condenser 145, and hydrogen is separated from lower boiling constituents in reflux tank 146. The hydrogen may leave the system as an overhead product stream 166, which in an embodiment may comprise trace amounts of additional components including ethanol, ethyl acetate, and/or one or more reaction byproducts. The condensed lower boiling constituents (i.e. , reflux), or at least some portion thereof, can be cycled back to the distillation column 144 for further reaction and/or separation. A takeoff stream 160 can be used to remove some portion of the byproducts, be recycled to the feed inlet for further reaction in the reactors 149, 151 , or serve as the inlet line to the first reactor 149.

[0053] The bottoms product from the distillation column 144, or at least a portion thereof, can be passed to a reboiler 147, where a portion of the bottoms product is evaporated and added back to the bottom of the distillation column 144. The remaining bottoms product may pass out of the system as product stream 163. Alternatively, the entire bottoms product may be passed through the reboiler 147, with the vapor portion passing back to the bottom of the column and the remainder of the bottoms product being passed out of the system as product stream 163 for further processes and/or use as a final product. The product stream 163 may comprise the ethyl acetate produced in the reactor 149 along with a minor amount of unreacted ethanol and potentially any side products produced by the reaction. The column reflux and reboil ratios are maintained such that higher purity ethyl acetate is obtained as the bottoms product. In an embodiment, the bottoms product stream 163 may comprise greater than about 70%, greater than about 80%, greater than about 90% ethyl acetate by weight.

[0054] Suitable dehydrogenation catalysts for use in the system are capable of converting at least a portion of the alcohol (e.g., ethanol) in a feed stream to a higher valued product such as ethyl acetate. Any catalyst capable of carrying out a dehydrogenation and dimerization reaction may be used alone or in combination with additional catalytic materials in the reactors. In an embodiment, suitable dehydrogenation and dimerization catalysts can generally comprise metals and/or oxides of copper, barium, ruthenium, rhodium, platinum, palladium, rhenium, silver, cadmium, zinc, zirconium, gold, thallium, magnesium, manganese, aluminum, chromium, nickel, iron, molybdenum, sodium, strontium, tin, and mixtures thereof. In many cases, the catalyst material will be provided on a support material. The catalyst can be treated with a carbonate (e.g., sodium carbonate), reduced with hydrogen, and/or other suitable treatments prior to use.

[0055] In certain embodiments, the dehydrogenation and dimerization catalyst may include a catalyst support. The catalyst support stabilizes and supports the catalyst. The type of catalyst support used depends on the chosen catalyst and the reaction conditions. Suitable supports may include, but are not limited to, carbon, silica, silica-alumina, alumina, zirconia, titania, ceria, vanadia, nitride, boron nitride, heteropolyacids, hydroxyapatite, zinc oxide, chromia, zeolites, carbon nanotubes, carbon fullerenes, and any combination thereof.

[0056] The dehydrogenation and dimerization catalyst can be employed in any of the conventional types or structures known to the art. It may be employed in the form of extrudates, pills, pellets, granules, broken fragments, or various special shapes. In an embodiment, consideration of the use of the catalyst in the reactive distillation system and/or as a mass transfer surface within the distillation column may be taken into account when determining a suitable shape. For example, the catalyst may have a shape similar to structured packing material or suitable for insertion in a structured packing. When the hydrogenation catalyst is used with one or more side reactors, the catalyst may be disposed within a reaction zone, and the feed may be passed therethrough in the liquid, vapor, or mixed phase, and in either upward or downward, or inward or outward flow.

|0057| The dehydrogenation and dimerization catalyst may typically have a range of metal loadings. In an embodiment, the catalyst may have a copper oxide weight loading (i.e., weight percentage) of between about 0.5% and about 80%, between about 10% and about 70 %, between about 20 % and about 65%, between about 30 % and about 60%, or about 40% and about 50%. In an embodiment, the catalyst may have a zinc oxide weight loading of between about 20% and about 60%, between about 30% and about 50%, or between about 40% and about 50%. In an embodiment, the catalyst may have a chromium oxide weight loading of between about 20% and about 60%, or between about 30% and about 50%.

[0058] In an embodiment, the dehydrogenation catalyst may comprise CuO/ZnO/AlzOs. In this embodiment, the catalyst may have a copper oxide weight loading of between about 0.5% and about 80%, between about 10% and about 70 %, between about 20 % and about 65%, between about 30 % and about 60%, or about 40% and about 50%, and the zinc oxide and alumina may comprise the balance of the weight. In an embodiment, the catalyst may comprise CuO/ZnO/ZrO2/Al2O3, and the catalyst may have a copper oxide weight loading of between about 40% to about 80%, with the remainder of the components forming the balance of the catalyst weight. In an embodiment, the catalyst may comprise CuO/ZnO/ZrO2/Cr2O3, and the catalyst may have a copper oxide weight loading of between about 20% to about 70% and a chromium oxide weight loading between about 30% and about 50%, with the remainder of the components forming the balance of the catalyst weight. In an embodiment, the catalyst may comprise CuOZ ZrC / AI2O3. In an embodiment, the catalyst comprises an alkaline earth metal and/or alkaline earth metal oxide and copper and/or copper oxide on a support. In this embodiment, the support may comprise silica.

[0059] Any of the materials useful as hydrogenation and dimerization catalysts, may be synthesized using a variety of methods. In an embodiment, the dehydrogenation and dimerization catalyst may be prepared via wet impregnation of a catalyst support. Using the wet-impregnation technique, a metal nitrate dissolved in a suitable solvent may be used to prepare the catalyst, however any soluble compound would be suitable. A sufficient amount of solvent should be used to fully dissolve the metal nitrate and appropriately wet the support. In one embodiment, copper nitrate and ethanol and/or water may be mixed in an amount sufficient such that the copper nitrate dissolves. Additional metal nitrates may also be added to provide a catalyst with additional components. The solute may then be combined with a suitable support material of appropriate particle size. The mixture may then be refluxed at a temperature of approximately 100 °C for approximately several hours (e.g., three to five hours) and then allowed to dry at a temperature of about 110 °C. The dried material may then be heated to 200 °C to remove the NOx component, and then the materials may be calcined at about 450 °C to about 550 °C at a heating rate of about one to ten °C /min. The amount of metal nitrate used in the wet-impregnation technique can be adjusted to achieve a desired final metal weight loading of the catalyst support.

[0060] When multiple components are used to provide a catalyst disposed on a support, each component can be added via the wet-impregnation technique. The appropriate salts can be dissolved and impregnated on a support in a coimpregnation process or a sequential process. In a co-impregnation process, measured amount of the appropriate plurality of metal salts may be dissolved in a suitable solvent and used to wet the desired catalyst support. The impregnated support can then be dried and calcined to provide a final catalyst with a desired weight loading. In the sequential impregnation process, one or more measured amounts of salts may be dissolved in a suitable solvent and used to wet the desired catalyst support. The impregnated support can then be dried and calcined. The resulting material can then be wetted with one or more additional salts that are dissolved in a suitable solvent. The resulting material can then be dried and calcined again. This process may be repeated to provide a final catalyst material with a desired loading of each component. In an embodiment, a single metal may be added with each cycle. The order in which the metals are added in the sequential process can be varied. Various metal weight loadings may be achieved through the wet-impregnation technique. In an embodiment, the wet-impregnation technique may be used to provide a catalyst having a copper weight loading ranging from about 0.5 % and about 50 %, with one or more additional components having a weight loading between about 0.1 % and about 10 %.

[0061] The dehydrogenation and dimerization catalysts may also be prepared via a co-precipitation technique. In this technique, a measured amount of one or more appropriate metal nitrates (or other appropriate metal salts) are dissolved in de-ionized water. The total metal concentration can vary and may generally be between about 1 M and about 3 M. The metal-nitrate solution may then be precipitated through the drop-wise addition of the solution to a stirred, equal volume of a sodium hydroxide solution at room temperature. The sodium hydroxide solution may generally have a concentration of about 4M, though other concentrations may also be used as would be known to one of skill in the art with the benefit of this disclosure. After addition of the metal nitrate solution, the resulting suspension can be filtered and washed with de-ionized water. The filtered solids can be dried overnight, for example, at a temperature of about 110 °C. The resulting mixed metal oxide can then be processed to a desired particle size. For example, the resulting mixed metal oxide can be pressed to a desired form, ground, and then sieved to recover a catalyst material with a particle size in a desired range. Catalysts prepared using the co-precipitation technique may have higher metal loadings than the catalysts prepared using the wet-impregnation technique.

[0062] The catalyst prepared via the co-precipitation technique may be used in the prepared form and/or a catalyst binder can be added to impart additional mechanical strength. In an embodiment, the prepared catalyst may be ground to a fine powder and then stirred into a colloidal suspension (e.g., a colloidal suspension of silica and/or alumina) in an aqueous solution. The resulting suspension may be stirred while being heated and allowed to evaporate to dryness. The heating may take place at about 80 °C to about 130 °C. The resulting solid can then be processed to a desired particle size. For example, the resulting solid can be pressed to a desired form, ground, and then sieved to recover a catalyst material with a particle size in a desired range. Alternatively, the colloidal suspension may be added to the 4M sodium hydroxide precipitation solution prior to addition of the metal nitrate solution in the co-precipitation technique. Various metal weight loadings may be achieved through the co-precipitation technique. In an embodiment, the co-precipitation technique may be used to provide a catalyst having a copper weight loading ranging from about 2 % and about 80 %, with one or more additional components having a weight loading between about 2% and about 40 %.

[0063] The resulting catalyst from either the wet-impregnation technique and/or the co-precipitation technique may be further treated prior to use in the reactive distillation system disclosed herein. In an embodiment, the catalyst may be treated with a sodium carbonate solution for a period of time to improve the selectivity of the catalyst. In this process, the catalyst may be soaked in an aqueous solution of sodium carbonate for a period of time ranging from about 1 hour to about 48 hours, or alternatively about 2 hours to about 24 hours. In an embodiment, the sodium carbonate solution may have a concentration of about 0.2 M. The catalyst may then be filtered and allowed to dry at about room temperature. In an embodiment, the sodium carbonate may comprise from about 0.2 to about 3.0 weight percent of the catalyst after being contacted with the sodium carbonate solution.

[0064] In another treatment process, the catalyst may be reduced with hydrogen prior to use. In this embodiment, the catalyst may be heated and contacted with hydrogen, which may be flowing over the catalyst, for a period of time sufficient to reduce the catalyst to a desired degree. In an embodiment, the catalyst may be contacted with hydrogen at a temperature of about 190 °C to about 240 °C. The hydrogen treatment may be conducted in combination with the sodium carbonate treatment, and may be performed prior to and/or after the sodium carbonate treatment.

[0065] Without intending to be limited by theory, it is believed that the production of hydrogen during the dehydrogenation and dimerization reaction within the process may result in contact between the dehydrogenation and dimerization catalyst and a hydrogen stream sufficient to at least partially reduce the catalyst. Thus, the process described herein may have the potential for the in- situ reduction of the catalyst during use. This may result in an initial break-in period in which the catalyst conversion and selectivity may change before reaching a steady state conversion and selectivity. This in-situ reduction may be taken into account when considering the degree to which a catalyst should be pre-reduced with hydrogen.

[0066] In an embodiment, the dehydrogenation and dimerization catalyst described herein may be capable of achieving a relatively high conversion and/or selectivity of ethanol to ethyl acetate. As used herein, the “conversion” of ethanol to ethyl acetate refers to the amount of ethanol consumed in the conversion reaction as represented by the formula:

where FEIOH represents the molar flow rates of ethanol in the reactor effluent (e.g., the product stream comprising the ethyl acetate), and FEIOH.O represents the molar flow rate of ethanol into the reactor inlet. As used herein, the “selectivity” of the conversion refers to the amount of ethanol that is consumed in the conversion reaction that is converted to ethyl acetate as represented by the formula:

where FEIOAC and FACH represent the molar flow rate of ethyl acetate and acetaldehyde in the reactor effluent (e.g., the product stream comprising the ethyl acetate), respectively, and the remaining terms are the same as described above with respect to the conversion of ethanol. In an embodiment, the dehydrogenation and dimerization catalyst described herein may be capable of achieving a conversion of ethanol in the reactive distillation process described herein of at least about 10%, at least about 20%, at least about 30%, at least about 40%, or at least about 50%. In an embodiment, the dehydrogenation and dimerization catalyst described herein may be capable of achieving a selectivity of ethyl acetate in the reactive distillation process described herein of at least about 60%, at least about 70%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 96%.

[0067] Another embodiment of a system 200 for producing ethyl acetate is illustrated in Figure 2. The embodiment of Figure 2 is similar to the embodiment described with respect to Figure 1 , and similar elements will not be described again in the interest of brevity. In this embodiment, the feed stream 155 can be introduced into an optional dehydration system 148, which removes water in the ethanol feed stream. The dehydrated feed stream can be passed to the first reactor 149 along with stream 156 from the distillation column 144. In an embodiment, stream 156 is dehydrated along with stream 155 before entering the first reactor 149. The first reactor 149 can contain a dehydrogenation catalyst that can convert ethanol into ethyl acetate and hydrogen. Any of the dehydrogenation catalyst described herein can be used in the first reactor 149. Further, the first reactor 149 can comprise a reactor section comprising a plurality of reactor vessels, heat exchangers, and the like as described with respect to Figure 1 . The effluent stream 157 from the first reactor 149 can be heated or cooled in the optional heat exchanger 150 before entering the second reactor 151 , which can contain the hydrogenation catalyst(s) as described herein. Hydrogen produced during reaction in the first reactor 149 and present in stream 158 can be used to hydrogenate any ketones and/or aldehydes (e.g., MEK, acetaldehyde, butyraldehyde and any other aldehyde and ketone byproducts etc.) present in the reactor effluent. As with the first reactor 149, the second reactor 149 can comprise a reactor section comprising a plurality of reactor vessels, heat exchangers, and the like as described with respect to Figure 1 . The first reactor 149 and the second reactor 151 can operate at the conditions described above with respect to Figure 1.

[0068] The outlet from the second reactor 151 can optionally be sent to a vaporliquid flash 152 to remove non-condensables such as hydrogen in stream 159. The liquid stream from the flash can be sent to the distillation column 144 for distillation separation. If the vapor-liquid flash 152 is not present, the hydrogen may be separated in the distillation column overhead and leave the system as an overhead product stream 166.

|0069| The distillation column 144 allows unconverted ethanol to be separated from ethyl acetate. As described with respect to Figure 1 , a vapor-liquid flash 146 can optionally be used to separate hydrogen in stream 166 from the distillate stream 160. Stream 160 can be further purified using distillation or other purification techniques in section 153 to recover any unconverted ethanol in stream 161. The separation section 153 can comprise one or more separation units such as distillation columns and flash tanks to separate the distillate stream 160 into a plurality of component streams. The ethanol recovered from the separation section 153 as stream 161 can be sent back to dehydration system 148 or directly to the first reactor 149 in case dehydration is not needed. As described above with respect to Figure 1 , stream 156 may be the same as stream 160 in some embodiments. In this embodiment, the distillate stream 160 can optionally pass to the dehydration unit 148 prior to passing to the first reactor 149, and stream 156 may not be separately present.

[0070] The bottoms stream from the distillation column 144 can be further purified by using distillation or other purification techniques in section 154 and ethanol can be recovered from this purification operation in stream 165, which can be sent back to dehydration system 148 or directly to the first reactor 149 in case dehydration is not needed. In addition to the ethanol present in stream 165, the separation section 154 can produce an ethyl acetate product stream 164 and optionally a byproducts stream 168. The separation section 154 can comprise one or more separation units such as distillation columns and flash tanks to separate the bottoms product stream 163 into a plurality of components. In an embodiment, the separation section 154 may comprise at least two distillation columns configured to separate the bottoms product stream 163 into the ethanol stream 165, the ethyl acetate product stream 164, and the optional byproducts stream 168. The separation section 154 can be configured to produce the ethyl acetate product stream 164 having an ethyl acetate purity of greater than about 90%, greater than about 95%, greater than about 96%, greater than about 97%, greater than about 98%, greater than about 99%, or greater than about 99.5% ethyl acetate by weight.

EXAMPLES

[0071] The disclosure having been generally described, the following examples are given as particular embodiments of the disclosure and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification or the claims in any manner.

EXAMPLE 1

[0072] In order to demonstrate the effectiveness of the hydrogenation catalysts, several different catalysts were tested in a tickle bed reactor operated at 350 psig, over a variety of temperatures and liquid hourly space velocities (LHSV). A liquid feed of 2 wt % MEK in ethyl acetate was introduced into the reactor along with a minimum 5X molar excess of hydrogen (relative to MEK). The liquid effluent from the reactor was analyzed to determine the concentration of MEK exiting the reactor. A 13 wt % CuO on alumina catalyst (ADS-12) manufactured by UOP, and several CuO/ZrCh/A^Os catalysts prepared via co-precipitation with different compositions, both with and without a binding agent, were prepared and tested. All catalysts were activated at 200 °C for 16 hours in a stream of hydrogen prior to operation.

[0073] Table 1 shows the results of the different catalysts at 100 °C as reactor LHSV changed. A 0.5 wt % ruthenium on alumina catalyst is included for comparison to a high performing precious metal-based catalyst. 1 -Cu/Zr/AI is a co-precipitated catalyst with 80 wt % CuO, 12 wt% ZrOz, and 8 wt% AI2O3. 2- Cu/Zr/AI is a co-precipitated catalyst with the same composition as 1-Cu/Zr/AI, but to which 20 wt% boehmite has been added as a catalyst binder. 3-Cu/Zr/AI is a co-precipitated catalyst with a composition of 67 wt% CuO, 10 wt% ZrO2, 23 wt % AI2O3.

Table 1 : Catalyst performance at 350 psig, 100 °C, with different reactor LHSV

MEK wt% in Effluent

Catalyst 2 hr¹ LHSV 4 hr¹ LHSV 8 hr¹ LHSV

ADS-12 0.003

1-Cu/Zr/AI 0.000 0.013 0.125

2-Cu/Zr/AI 0.042 0.350 0.782

3-Cu/Zr/AI 0.013 0.085 0.460

0.5 wt % Ru on Alumina 0.004 0.038 0.171

[0074] Table 1 shows that two of the four copper-based catalysts outperform the ruthenium based catalyst. Both the ADS-12 and the 1-Cu/Zr/AI catalysts have lower MEK effluent concentrations than the ruthenium catalyst, with 1-Cu/Zr/AI achieving complete conversion at an LHSV of 2 hr¹. While 2-Cu/Zr/AI and 3- Cu/Zr/AI are not as active as the other samples, all of the catalysts are capable of converting greater than 98% of the MEK in the reactor feed into 2-butanol at an LHSV of 2 hr¹.

[0075] A major concern when using copper catalysts for a hydrogenation reaction in the presence of an ester would be the hydrogenation of the ester into alcohols. Under the conditions explored in Table 1 , the concentration of ethanol in the reactor effluent remained below 0.3 wt% in all cases. The hydrogenation of ethyl acetate to ethanol occurs in only minor amounts at these conditions, and most of the ethanol seen in the effluent is likely generated from the transesterification of ethyl acetate with 2-butanol to form sec-butyl acetate and ethanol. [0076] Due to the low amount of ester hydrogenation observed at 100 °C, some catalysts were also tested at higher reaction temperatures which provide higher reactivity for aldehyde and ketone hydrogenation, but could also lead to significant ester hydrogenation. Tables 2-4 show the results of three catalysts tested at a variety of temperatures using a reactor LHSV of 2 hr¹. The tables show both the MEK and ethanol effluent compositions.

Table 2: ADS-12 performance at 350 psig, 2 hr¹ LHSV at diffe rent temperatures

Temperature ( °C) MEK wt% Ethanol wt%

100 0.003 0.27

120 0.004 0.13

150 0.009 0.29

180 0.038 0.98

Table 3: 2-Cu/Zr/AI performance at 350 psig, 2 hr¹ LHSV at d ifferent temperatures

Temperature ( °C) MEK wt% Ethanol wt%

100 0.018 0.07

150 0.010 0.38

180 0.036 1.23 Table 4: 3-Cu/Zr/AI performance at 350 psig, 2 hr¹ LHSV at d if f e re n t te m pe rat u res

Temperature ( °C) MEK wt% Ethanol wt%

100 0.013 0.08

120 0.000 0.15

150 0.011 0.53

180 0.042 1.87

[0077] All three catalysts show that as temperature increases, the amount of ethanol produced from the hydrogenation of ethyl acetate increases. However, even at 180 °C only a small portion of the ethyl acetate is consumed. The tables also demonstrate that at high temperatures, the conversion of MEK to 2-butanol appears to become limited by thermodynamic equilibrium.

EXAMPLE 2

[0078] Additional catalyst testing was performed to verify the performance of the hydrogenation catalysts. Exemplary catalysts for this example had the following compositions, as depicted in Table 5.

TABLE 5

[0079] Catalyst Number 5 has added boehmite in an amount of about 10 %, by weight, of catalyst, on top, with the amount of boehmite dependent on high- throughput experimentation. The AI2O3 support used is sold under the trade designation Puralox™ is commercially available from Sasol Limited of Sandton, South Africa. After being prepared, the catalyst can be dried at 110 °C overnight, and then dried again at 200 °C for 2 hours to remove nitrous oxides (NOx). Subsequently, catalyst can be calcinated 500 °C for 1 hour by ramping the temperature at a rate of 5 °C per minute.

The catalysts were tested at a LHSV of 2, 100 C, and a pressure of 24 barg, which resulted in the following conversions of MEK in the samples:

TABLE 6

The results demonstrate the hydrogenation of the byproducts in the sample reactant stream.

[0080] Having described various catalysts, systems, and methods, certain aspects can include, but are not limited to:

[0081] In a first aspect, a method of selectively hydrogenating ketones or aldehydes comprises: contacting a reaction mixture with a hydrogenation catalyst under hydrogenation reaction conditions, wherein the reaction mixture comprises hydrogen, at least one ester, and at least one ketone or aldehyde, wherein the hydrogenation catalyst comprises copper or copper oxide; and hydrogenating at least a portion of the at least one ketone or aldehyde to form an alcohol, wherein less than 5% by weight of the ester is converted to one or more reaction products. [0082] A second aspect can include the method of the first aspect, wherein the portion of the at least one ketone or aldehyde comprises at least about 95% by weight of the at least one ketone or aldehyde.

[0083] A third aspect can include the method of the first or second aspect, wherein the at least one ester comprises ethyl acetate.

[0084] A fourth aspect can include the method of any one of the first to third aspects, wherein the at least one ketone or aldehyde comprises methyl ethyl ketone.

[0085] A fifth aspect can include the method of any one of the first to third aspects, wherein the at least one ketone or aldehyde comprises n-butyraldehyde, acetaldehyde, crotonaldehyde, or any combination thereof.

[0086] A sixth aspect can include the method of any one of the first to fifth aspects, wherein the reaction mixture comprises between about 0.01 % by weight and about 10% by weight of the at least one of the ketone or aldehyde.

[0087] A seventh aspect can include the method of any one of the first to sixth aspects, wherein the reaction mixture comprises between about 1.5 times and about 10 times the amount of hydrogen as the at least one ketone or aldehyde on a molar basis.

[0088] An eighth aspect can include the method of any one of the first to seventh aspects, wherein the hydrogenation catalyst comprises at least about 10% by weight of copper.

[0089] A ninth aspect can include the method of any one of the first to eighth aspects, wherein the hydrogenation catalyst comprises zirconium or zirconium oxide. [0090] A tenth aspect can include the method of any one of the first to ninth aspects, wherein the hydrogenation reaction conditions comprise a liquid hourly space velocity between about 0.25 hr¹ to about 10 hr¹.

[0091] An eleventh aspect can include the method of any one of the first to tenth aspects, wherein the hydrogenation reaction conditions comprise a temperature between about 80 °C to about 150 °C.

[0092] A twelfth aspect can include the method of any one of the first to eleventh aspects, wherein the hydrogenation reaction conditions comprise a pressure between about 1 atm to about 50 atm.

[0093] A thirteenth aspect can include the method of any one of the first to twelfth aspects, further comprising: separating the at least one ester from the reaction mixture to form a product, wherein an amount of the at least one ketone or aldehyde in the product is less than an amount of the at least on ketone or aldehyde in the reaction mixture.

[0094] A fourteenth aspect can include the method of the thirteenth aspect, wherein the amount of the at least one ketone or aldehyde in the product is less than an azeotropic concentration of the at least one ketone or aldehyde with the at least one ester.

[0095] In a fifteenth aspect, a method of producing ethyl acetate comprises: feeding a feed stream comprising ethanol to a reactor system, wherein the reactor system comprises a distillation column and at least one side reactor in fluid communication with the distillation column; contacting the feed stream with a dehydrogenation catalyst in at least one of the distillation column or the at least one side reactor; dehydrogenating ethanol over the dehydrogenation catalyst to produce ethyl acetate and at least one side product; contacting the ethyl acetate and the at least one side product with a hydrogenation catalyst in at least one of the distillation column or the at least one side reactor; hydrogenating at least a portion of the at least one side product; removing at least a portion of the ethyl acetate in a bottoms product stream; and removing hydrogen as an top product stream.

[0096] A sixteenth aspect can include the method of the fifteenth aspect, wherein the at least one side reactor comprises a plurality of side reactors, wherein an inlet of a first side reactor of the plurality of side reactors is coupled to the distillation column, wherein an outlet of the first side reactor is coupled to an inlet of a second side reactor of the plurality of side reactors, and wherein an outlet of the second side reactor is coupled to the distillation column.

[0097] A seventeenth aspect can include the method of the fifteenth aspect, wherein the at least one side reactor comprises a plurality of side reactors, wherein an inlet of a first side reactor of the plurality of side reactors is coupled to the distillation column, wherein an outlet of the first side reactor is coupled to the distillation column, wherein an inlet of a second side reactor of the plurality of side reactors is coupled to the distillation column, and wherein an outlet of the second side reactor is coupled to the distillation column. [0098] An eighteenth aspect can include the method of the sixteenth or seventeenth aspect, wherein the dehydrogenation catalyst is disposed in the first side reactor, and wherein the hydrogenation catalyst is disposed in the second side reactor. [0099] A nineteenth aspect can include the method of any one of the sixteenth to eighteenth aspects, wherein a reaction condition in the first side reactor is different than a reaction condition in the second side reactor.

[00100] A twentieth aspect can include the method of any one of the sixteenth to nineteenth aspects, further comprising: cooling the ethyl acetate and the at least one side product prior to contacting the ethyl acetate and the at least one side product with the hydrogenation catalyst.

[00101] A twenty first aspect can include the method of any one of the sixteenth to twentieth aspects, wherein feeding the feed stream to the reactor system comprises feeding the feed stream to the inlet of the first side reactor.

[00102] A twenty second aspect can include the method of any one of the fifteenth to twenty first aspects, wherein the hydrogenation catalyst comprises copper or copper oxide.

[00103] A twenty third aspect can include the method of the twenty second aspect, wherein the hydrogenation catalyst further comprises at least one of aluminum, zirconium, an oxide thereof, or any combination thereof.

[00104] A twenty fourth aspect can include the method of any one of the fifteenth to twenty third aspects, further comprising: dehydrating the feed stream prior to feeding the feed stream to the reactor system.

[00105] A twenty fifth aspect can include the method of any one of the fifteenth to twenty fourth aspects, wherein the distillation column does not comprise a catalyst.

[00106] A twenty sixth aspect can include the method of any one of the fifteenth to twenty fifth aspects, further comprising: separating the bottoms product stream to produce an ethyl acetate product stream and a byproducts stream.

[00107] A twenty seventh aspect can include the method of the twenty sixth aspect, wherein the ethyl acetate product stream comprises at least 95% ethyl acetate.

|00108| A twenty eighth aspect can include the method of any one of the fifteenth to twenty seventh aspects, wherein the dehydrogenation catalyst comprises at least one catalytic component selected from the group consisting of: copper, copper oxide, barium, barium oxide, ruthenium, ruthenium oxide, rhodium, rhodium oxide, platinum, platinum oxide, palladium, palladium oxide, rhenium, rhenium oxide, silver, silver oxide, cadmium, cadmium oxide, zinc, zinc oxide, zirconium, zirconium oxide, gold, gold oxide, thallium, thallium oxide, magnesium, magnesium oxide, manganese, manganese oxide, aluminum, aluminum oxide, chromium, chromium oxide, nickel, nickel oxide, iron, iron oxide, molybdenum, molybdenum oxide, sodium, sodium oxide, sodium carbonate, strontium, strontium oxide, tin, tin oxide, and any mixture thereof.

[00109] A twenty ninth aspect can include the method of the twenty eighth aspect, wherein the dehydrogenation catalyst comprises a support, wherein the support comprises at least one support material selected from the group consisting of: carbon, silica, silica-alumina, alumina, zirconia, titania, ceria, vanadia, nitride, boron nitride, heteropolyacids, hydroxyapatite, zinc oxide, chromia, a zeolite, a carbon nanotube, carbon fullerene, and any combination thereof.

[00110] A thirtieth aspect can include the method of any one of the fifteenth to twenty ninth aspects, wherein the dehydrogenation catalyst comprises copper, and wherein the catalyst has a copper weight loading of between about 0.5% and about 80% of the catalyst.

[00111] A thirty first aspect can include the method of any one of the fifteenth to thirtieth aspects, further comprising: removing a reactant stream from the distillation column during a distillation; and passing the reactant stream to the at least one side reactor with the feed stream.

|00112| A thirty second aspect can include the method of the thirty first aspect, wherein at least a portion of the reactant stream or the feed stream is a vapor within the at least one side reactor.

[00113] A thirty third aspect can include the method of the thirty first or thirty second aspect, wherein the reactant stream comprises at least a portion of an overhead stream passing out of the top of the distillation column.

[00114] A thirty fourth aspect can include the method of any one of the thirty first to thirty third aspects, further comprising: dehydrating the feed stream and the reactant stream prior to passing the reactant stream and the feed stream to the at least one side reactor.

[00115] A thirty fifth aspect can include the method of the thirty fourth aspect, further comprising: heating the feed stream and the reactant stream prior to passing the reactant stream and the feed stream to the at least one side reactor, wherein at least a portion of the feed stream, the reactant stream, or both is a vapor within the at least one side reactor.

[00116] In a thirty sixth aspect, a reactor system for producing ethyl acetate comprises: a distillation column; a first side reactor comprising a first inlet and a first outlet, wherein the first inlet is in fluid communication with the distillation column, wherein the first side reactor comprises a dehydrogenation catalyst; and a second side reactor comprising a second inlet and a second outlet, wherein the second inlet is in fluid communication with the first outlet of the first side reactor, wherein the second outlet is in fluid communication with the distillation column, and wherein the second side reactor comprises a hydrogenation catalyst, wherein the distillation column comprises an overhead product removal passage and a bottoms product ethyl acetate removal passage.

[00117] A thirty seventh aspect can include the system of the thirty sixth aspect, wherein the hydrogenation catalyst comprises copper or copper oxide.

[00118] A thirty eighth aspect can include the system of the thirty seventh aspect, wherein the hydrogenation catalyst further comprises at least one of aluminum, zirconium, nickel, an oxide thereof, or any combination thereof.

[00119] A thirty ninth aspect can include the system of any one of the thirty sixth to thirty eighth aspects, wherein the dehydrogenation catalyst comprises at least one catalytic component selected from the group consisting of: copper, copper oxide, barium, barium oxide, ruthenium, ruthenium oxide, rhodium, rhodium oxide, platinum, platinum oxide, palladium, palladium oxide, rhenium, rhenium oxide, silver, silver oxide, cadmium, cadmium oxide, zinc, zinc oxide, zirconium, zirconium oxide, gold, gold oxide, thallium, thallium oxide, magnesium, magnesium oxide, manganese, manganese oxide, aluminum, aluminum oxide, chromium, chromium oxide, nickel, nickel oxide, iron, iron oxide, molybdenum, molybdenum oxide, sodium, sodium oxide, sodium carbonate, strontium, strontium oxide, tin, tin oxide, and any mixture thereof.

[00120] A fortieth aspect can include the system of the thirty ninth aspect, wherein the dehydrogenation catalyst comprises a support, wherein the support comprises at least one support material selected from the group consisting of: carbon, silica, silica- alumina, alumina, zirconia, titania, ceria, vanadia, nitride, boron nitride, heteropolyacids, hydroxyapatite, zinc oxide, chromia, a zeolite, a carbon nanotube, carbon fullerene, and any combination thereof.

[00121] A forty first aspect can include the system of any one of the thirty sixth to fortieth aspects, wherein the dehydrogenation catalyst comprises copper, and wherein the catalyst has a copper weight loading of between about 0.5% and about 80% of the catalyst.

[00122] A forty second aspect can include the system of any one of the thirty sixth to forty first aspects, wherein the distillation column does not comprise a catalyst.

[00123] A forty third aspect can include the system of any one of the thirty sixth to forty second aspects, further comprising: a heat exchanger, wherein an inlet of the heat exchanger is fluidly coupled to the first outlet, and wherein an outlet of the heat exchanger is fluidly coupled to the second inlet, wherein the heat exchanger is configured to indirectly contact an outlet stream from the first side reactor with a coolant fluid.

[00124] A forty fourth aspect can include the system of any one of the thirty sixth to forty third aspects, further comprising: a feed inlet to the reactor system, wherein the feed inlet is in fluid communication with the first inlet.

1001251 A forty fifth aspect can include the system of the forty fourth aspect, further comprising: a dehydration unit, wherein the dehydration unit is fluidly disposed between the feed inlet and the first side reactor.

[00126] A forty sixth aspect can include the system of any one of the thirty sixth to forty fifth aspects, further comprising: a separator fluidly disposed between the second side reactor and the distillation column, wherein the separator comprises a phase separator, wherein a gas stream is produced as an overhead stream from the separator, and wherein the separator is configured to pass a liquid stream to the distillation column.

[00127] A forty seventh aspect can include the system of any one of the thirty sixth to forty fifth aspects, further comprising: a product separator in fluid communication with the bottoms product ethyl acetate removal passage, wherein the product separator is configured to separate a bottoms product stream into a recycle stream comprising unreacted ethanol and an ethyl acetate product stream, wherein the product separator is configured to pass the recycle stream to an inlet of the first side reactor.

[00128] A forty eighth aspect can include the system of any one of the thirty sixth to forty seventh aspects, further comprising: a reactant stream passage, wherein the reactant stream passage is configured to provide fluid communication between the distillation column and the first inlet.

[00129] A forty ninth aspect can include the system of the forty eighth aspect, wherein the reactant stream passage is configured to provide fluid communication between the overhead product removal passage and the first inlet.

[00130] In the preceding discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to ...”. At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11 , 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, Ri, and an upper limit, R_u, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=Ri+k*(Ru-Ri), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, ... , 50 percent, 51 percent, 52 percent, ... , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term "optionally" with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present invention.

Claims

CLAIMS We claim:

1 . A method of selectively hydrogenating ketones or aldehydes, the method comprising: contacting a reaction mixture with a hydrogenation catalyst under hydrogenation reaction conditions, wherein the reaction mixture comprises hydrogen, at least one ester, and at least one ketone or aldehyde, wherein the hydrogenation catalyst comprises copper or copper oxide; and hydrogenating at least a portion of the at least one ketone or aldehyde to form an alcohol, wherein less than 5% by weight of the ester is converted to one or more reaction products.

2. The method of claim 1 , wherein the portion of the at least one ketone or aldehyde comprises at least about 95% by weight of the at least one ketone or aldehyde.

3. The method of claim 1 , wherein the at least one ester comprises ethyl acetate.

4. The method of claim 1 , wherein the at least one ketone or aldehyde comprises methyl ethyl ketone.

5. The method of claim 1 , wherein the at least one ketone or aldehyde comprises n-butyraldehyde, acetaldehyde, crotonaldehyde, or any combination thereof.

6. The method of claim 1 , wherein the reaction mixture comprises between about 0.01 % by weight and about 10% by weight of the at least one of the ketone or aldehyde.

7. The method of claim 1 , wherein the reaction mixture comprises between about 1.5 times and about 10 times the amount of hydrogen as the at least one ketone or aldehyde on a molar basis.

8. The method of claim 1 , wherein the hydrogenation catalyst comprises at least about 10% by weight of copper.

9. The method of claim 1 , wherein the hydrogenation catalyst comprises zirconium, zirconium oxide, nickel, or nickel oxide.

10. The method of claim 1 , wherein the hydrogenation reaction conditions comprise a liquid hourly space velocity between about 0.25 hr¹ to about 10 hr¹.

1 1. The method of claim 1 , wherein the hydrogenation reaction conditions comprise a temperature between about 80 °C to about 150 °C.

12. The method of claim 1 , wherein the hydrogenation reaction conditions comprise a pressure between about 1 atm to about 50 atm.

13. The method of claim 1 , further comprising: separating the at least one ester from the reaction mixture to form a product, wherein an amount of the at least one ketone or aldehyde in the product is less than an amount of the at least on ketone or aldehyde in the reaction mixture.

14. The method of claim 13, wherein the amount of the at least one ketone or aldehyde in the product is less than an azeotropic concentration of the at least one ketone or aldehyde with the at least one ester.

15. A method of producing ethyl acetate comprising: feeding a feed stream comprising ethanol to a reactor system, wherein the reactor system comprises a distillation column and at least one side reactor in fluid communication with the distillation column; contacting the feed stream with a dehydrogenation catalyst in at least one of the distillation column or the at least one side reactor; dehydrogenating ethanol over the dehydrogenation catalyst to produce ethyl acetate and at least one side product; contacting the ethyl acetate and the at least one side product with a hydrogenation catalyst in at least one of the distillation column or the at least one side reactor; hydrogenating at least a portion of the at least one side product; removing at least a portion of the ethyl acetate in a bottoms product stream; and removing hydrogen as an top product stream.

16. The method of claim 15, wherein the at least one side reactor comprises a plurality of side reactors, wherein an inlet of a first side reactor of the plurality of side reactors is coupled to the distillation column, wherein an outlet of the first side reactor is coupled to an inlet of a second side reactor of the plurality of side reactors, and wherein an outlet of the second side reactor is coupled to the distillation column.

17. The method of claim 15, wherein the at least one side reactor comprises a plurality of side reactors, wherein an inlet of a first side reactor of the plurality of side reactors is coupled to the distillation column, wherein an outlet of the first side reactor is coupled to the distillation column, wherein an inlet of a second side reactor of the plurality of side reactors is coupled to the distillation column, and wherein an outlet of the second side reactor is coupled to the distillation column.

18. The method of claim 16, wherein the dehydrogenation catalyst is disposed in the first side reactor, and wherein the hydrogenation catalyst is disposed in the second side reactor.

19. The method of claim 16, wherein a reaction condition in the first side reactor is different than a reaction condition in the second side reactor.

20. The method of claim 16, further comprising: cooling the ethyl acetate and the at least one side product prior to contacting the ethyl acetate and the at least one side product with the hydrogenation catalyst.

21. The method of claim 16, wherein feeding the feed stream to the reactor system comprises feeding the feed stream to the inlet of the first side reactor.

22. The method of claim 15, wherein the hydrogenation catalyst comprises copper or copper oxide.

23. The method of claim 22, wherein the hydrogenation catalyst further comprises at least one of aluminum, zirconium, nickel, an oxide thereof, or any combination thereof.

24. The method of claim 15, further comprising: dehydrating the feed stream prior to feeding the feed stream to the reactor system.

25. The method of claim 15, wherein the distillation column does not comprise a catalyst.

26. The method of claim 15, further comprising: separating the bottoms product stream to produce an ethyl acetate product stream and a byproducts stream.

27. The method of claim 26, wherein the ethyl acetate product stream comprises at least 95% ethyl acetate.

28. The method of claim 15, wherein the dehydrogenation catalyst comprises at least one catalytic component selected from the group consisting of: copper, copper oxide, barium, barium oxide, ruthenium, ruthenium oxide, rhodium, rhodium oxide, platinum, platinum oxide, palladium, palladium oxide, rhenium, rhenium oxide, silver, silver oxide, cadmium, cadmium oxide, zinc, zinc oxide, zirconium, zirconium oxide, gold, gold oxide, thallium, thallium oxide, magnesium, magnesium oxide, manganese, manganese oxide, aluminum, aluminum oxide, chromium, chromium oxide, nickel, nickel oxide, iron, iron oxide, molybdenum, molybdenum oxide, sodium, sodium oxide, sodium carbonate, strontium, strontium oxide, tin, tin oxide, and any mixture thereof.

29. The method of claim 28, wherein the dehydrogenation catalyst comprises a support, wherein the support comprises at least one support material selected from the group consisting of: carbon, silica, silica-alumina, alumina, zirconia, titania, ceria, vanadia, nitride, boron nitride, heteropolyacids, hydroxyapatite, zinc oxide, chromia, a zeolite, a carbon nanotube, carbon fullerene, and any combination thereof.

30. The method of claim 15, wherein the dehydrogenation catalyst comprises copper, and wherein the catalyst has a copper weight loading of between about 0.5% and about 80% of the catalyst.

31 . The method of claim 15, further comprising: removing a reactant stream from the distillation column during a distillation; passing the reactant stream to the at least one side reactor with the feed stream.

32. The method of claim 31 , wherein at least a portion of the reactant stream or the feed stream is a vapor within the at least one side reactor.

33. The method of claim 31 , wherein the reactant stream comprises at least a portion of an overhead stream passing out of the top of the distillation column.

34. The method of claim 31 , further comprising: dehydrating the feed stream and the reactant stream prior to passing the reactant stream and the feed stream to the at least one side reactor.

35. The method of claim 34, further comprising: heating the feed stream and the reactant stream prior to passing the reactant stream and the feed stream to the at least one side reactor, wherein at least a portion of the feed stream, the reactant stream, or both is a vapor within the at least one side reactor.

36. A reactor system for producing ethyl acetate, the system comprising: a distillation column; a first side reactor comprising a first inlet and a first outlet, wherein the first inlet is in fluid communication with the distillation column, wherein the first side reactor comprises a dehydrogenation catalyst; and a second side reactor comprising a second inlet and a second outlet, wherein the second inlet is in fluid communication with the first outlet of the first side reactor, wherein the second outlet is in fluid communication with the distillation column, and wherein the second side reactor comprises a hydrogenation catalyst, wherein the distillation column comprises an overhead product removal passage and a bottoms product ethyl acetate removal passage.

37. The system of claim 36, wherein the hydrogenation catalyst comprises copper or copper oxide.

38. The system of claim 37, wherein the hydrogenation catalyst further comprises at least one of aluminum, zirconium, nickel, an oxide thereof, or any combination thereof.

39. The system of claim 36, wherein the dehydrogenation catalyst comprises at least one catalytic component selected from the group consisting of: copper, copper oxide, barium, barium oxide, ruthenium, ruthenium oxide, rhodium, rhodium oxide, platinum, platinum oxide, palladium, palladium oxide, rhenium, rhenium oxide, silver, silver oxide, cadmium, cadmium oxide, zinc, zinc oxide, zirconium, zirconium oxide, gold, gold oxide, thallium, thallium oxide, magnesium, magnesium oxide, manganese, manganese oxide, aluminum, aluminum oxide, chromium, chromium oxide, nickel, nickel oxide, iron, iron oxide, molybdenum, molybdenum oxide, sodium, sodium oxide, sodium carbonate, strontium, strontium oxide, tin, tin oxide, and any mixture thereof.

40. The system of claim 39, wherein the dehydrogenation catalyst comprises a support, wherein the support comprises at least one support material selected from the group consisting of: carbon, silica, silica-alumina, alumina, zirconia, titania, ceria, vanadia, nitride, boron nitride, heteropolyacids, hydroxyapatite, zinc oxide, chromia, a zeolite, a carbon nanotube, carbon fullerene, and any combination thereof.

41. The system of claim 36, wherein the dehydrogenation catalyst comprises copper, and wherein the catalyst has a copper weight loading of between about 0.5% and about 80% of the catalyst.

42. The system of claim 36, wherein the distillation column does not comprise a catalyst.

43. The system of claim 36, further comprising: a heat exchanger, wherein an inlet of the heat exchanger is fluidly coupled to the first outlet, and wherein an outlet of the heat exchanger is fluidly coupled to the second inlet, wherein the heat exchanger is configured to indirectly contact an outlet stream from the first side reactor with a coolant fluid.

44. The system of claim 36, further comprising: a feed inlet to the reactor system, wherein the feed inlet is in fluid communication with the first inlet.

45. The system of claim 44, further comprising: a dehydration unit, wherein the dehydration unit is fluidly disposed between the feed inlet and the first side reactor.

46. The system of claim 36, further comprising: a separator fluidly disposed between the second side reactor and the distillation column, wherein the separator comprises a phase separator, wherein a gas stream is produced as an overhead stream from the separator, and wherein the separator is configured to pass a liquid stream to the distillation column.

47. The system of claim 36, further comprising; a product separator in fluid communication with the bottoms product ethyl acetate removal passage, wherein the product separator is configured to separate a bottoms product stream into a recycle stream comprising unreacted ethanol and an ethyl acetate product stream, wherein the product separator is configured to pass the recycle stream to an inlet of the first side reactor.

48. The system of claim 36, further comprising: a reactant stream passage, wherein the reactant stream passage is configured to provide fluid communication between the distillation column and the first inlet.

49. The system of clam 48, wherein the reactant stream passage is configured to provide fluid communication between the overhead product removal passage and the first inlet.