WO2024163090A1

WO2024163090A1 - Process for dehydrogenating an alkanol to produce acetaldehyde

Info

Publication number: WO2024163090A1
Application number: PCT/US2023/085640
Authority: WO
Inventors: Amit HASABNIS
Original assignee: Viridis Chemical, Llc
Priority date: 2023-01-30
Filing date: 2023-12-22
Publication date: 2024-08-08

Abstract

A process for dehydrogenating an alkanol can include contacting a feed including ethanol with a catalyst including copper or a copper oxide in a dehydrogenation zone of a reactor to obtain a conversion product including acetaldehyde. The dehydrogenation zone can include a vapor phase. The conversion of the ethanol can be at least about 30%, and the selectivity to the acetaldehyde can be at least about 50%.

Description

PROCESS FOR DEHYDROGENATING AN ALKANOL TO PRODUCE

ACETALDEHYDE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of U.S. Provisional Application No. 63/482,180 filed on January 30, 2023 and entitled “PROCESS FOR DEHYDROGENATING AN ALKANOL,"’ which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] The following discussion is provided solely to assist the understanding of the reader, and does not constitute an admission that any of the information discussed or references cited constitute prior art to the present invention.

[0003] Acetaldehyde can be produced from ethanol. One particular problem in the production of acetaldehyde by dehydrogenation of ethanol is that the reaction product mixture tends to be a complex mixture including esters, alcohols, aldehydes and ketones. The reaction mixture can be even more complex when the ethanol feed contains impurities. The reaction product mixtures contain components with boiling points close to acetaldehyde, and/or other components of the mixture. Another problem is that excess water present in the feed ethanol or produced as a by-product during dehydrogenation can result in the formation of undesired byproducts so that any recycle to the dehydrogenation reactor of unconverted ethanol should desirably contain only a low level, if any, of water.

SUMMARY

[0004] The present disclosure relates generally to processes for dehydrogenating an alkanol or for separating acetaldehyde from ethanol. More particularly, the present disclosure relates to contacting a feed including ethanol with a catalyst, which can comprise copper or a copper oxide, in a dehydrogenation zone of a reactor to obtain a conversion product comprising acetaldehyde, and optionally introducing a feed from the dehydrogenation zone comprising acetaldehyde and ethanol to a distillation column; separating an overhead stream comprising acetaldehyde; refluxing at least a portion of the overhead stream to the distillation column and recovering a distillate; and separating a bottoms stream comprising ethanol.

[0005] In some embodiments, a process for dehydrogenating an alkanol, the process comprising: contacting a feed comprising ethanol with a catalyst comprising copper or a copper oxide in a dehydrogenation zone of a reactor to obtain a conversion product comprising acetaldehyde, wherein the dehydrogenation zone comprises a vapor phase. In some embodiments, hydrogen is not introduced separately from the feed to the dehydrogenation zone, and dehydrogenation can be undertaken under any suitable conditions, such as a pressure in the dehydrogenation zone up to about 50 bar, the temperature in the dehydrogenation zone from about 100 °C to about 300 °C, and the liquid hourly space velocity in the dehydrogenation zone from about 0.5 hr¹ to about 10 hr¹, or about 0.5 hr¹ to about 1.0 hr¹.

[0006] The catalyst can include copper, chromium, manganese, aluminum, zinc, nickel, or a combination thereof in the form of at least one oxide; a copper oxide and a zinc or a zinc oxide; or consists of a copper oxide, a zinc oxide, and a support. In some embodiments, the catalyst can further include chromium, manganese, aluminum, zinc, nickel, zirconium, or a combination thereof or a support comprising alumina.

[0007] In some embodiments, a process for separating acetaldehyde from ethanol, comprising: introducing a feed comprising acetaldehyde and ethanol to a distillation column; separating an overhead stream comprising acetaldehyde; refluxing at least a portion of the overhead stream to the distillation column and recovering a distillate; and separating a bottoms stream comprising ethanol. The feed can include at least about 25%, by weight, acetaldehyde and at least about 65%, by weight, ethanol based on the total weight of the feed; the distillate can include at least about 99%, by weight, acetaldehyde based on the total weight of the distillate, and/or the bottoms stream can include at least about 95%, by weight, ethanol based on the total weight of the bottoms stream. In some embodiments, the process can further include introducing the bottoms stream to an ethanol recovery column; separating an ethanol recovery overhead stream comprising ethanol; and separating an ethanol recovery bottoms stream comprising ethanol and one or more CT hydrocarbons. The ethanol recovery overhead stream can include at least about 97%, by w eight, ethanol based on the total weight of the ethanol recovery overhead stream, and the ethanol recovery bottoms stream can include at least about 85%, by weight, ethanol and no more than about 15%, by weight, one or more CT hydrocarbons based on the total weight of the bottoms stream.

[0008] In some embodiments, a process for dehydrogenating an alkanol, the process can include: contacting a feed comprising ethanol with a catalyst comprising copper or a copper oxide in a dehydrogenation zone of a reactor to obtain a conversion product comprising acetaldehyde, wherein the dehydrogenation zone comprises a vapor phase; introducing a dehydrogenation zone effluent comprising acetaldehyde and ethanol to a distillation column; separating an overhead stream comprising acetaldehyde; refluxing at least a portion of the overhead stream to the distillation column and recovering a distillate; and separating a bottoms stream comprising ethanol.

[0009] In some embodiments, hydrogen is not introduced separately from the feed to the dehydrogenation zone, and dehydrogenation can be undertaken under any suitable conditions, such as a pressure in the dehydrogenation zone of up to about 50 bar, the temperature in the dehydrogenation zone from about 100 °C to about 300 °C, and the liquid hourly space velocity in the dehydrogenation zone from about 0.5 hr¹ to about 10 hr’¹, or about 0.5 hr’¹ to about 1.0 hr¹.

[0010] The present systems and methods may allow for a one-step acetaldehyde production process, which may be advantageous relative to other processes that require further steps to purify the acetaldehyde product. Each of these advantages may be provided in a process that can also be less expensive than alternative processes by acetaldehyde production from ethanol. [0011] In some embodiments, a process for separating acetaldehyde from ethanol, comprising: introducing a feed comprising acetaldehyde and ethanol to a distillation column; separating an overhead stream comprising acetaldehyde; refluxing at least a portion of the overhead stream to the distillation column and recovering a distillate; and separating a bottoms stream comprising ethanol. The feed can include at least about 25%, by weight, acetaldehyde and at least about 65%, by weight, ethanol based on the total weight of the feed; the distillate can include at least about 99%, by weight, acetaldehyde based on the total weight of the distillate, and/or the bottoms stream can include at least about 95%, by weight, ethanol based on the total weight of the bottoms stream. In some embodiments, the process can further include introducing the bottoms stream to an ethanol recovery column; separating an ethanol recovery overhead stream comprising ethanol; and separating an ethanol recovery bottoms stream comprising ethanol and one or more CT hydrocarbons. The ethanol recovery overhead stream can include at least about 97%, by w eight, ethanol based on the total weight of the ethanol recovery overhead stream, and the ethanol recovery bottoms stream can include at least about 85%, by weight, ethanol and no more than about 15%, by weight, one or more CT hydrocarbons based on the total weight of the bottoms stream.

[0012] 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

[0013] 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.

[0014] FIG. 1 shows a simplified schematic of a dehydrogenation zone of a chemical manufacturing facility according to some embodiments.

[0015] FIG. 2 shows a simplified schematic of a part of a downstream separation section for the chemical manufacturing facility according to some embodiments.

[0016] FIG. 3 shows a simplified schematic of another part of a downstream separation section for the chemical manufacturing facility according to some embodiments.

[0017] FIG. 4 shows a simplified schematic of a system according to some embodiments.

[0018] FIG. 5 shows a simplified schematic of a further system according to some embodiments.

[0019] FIG. 6 shows a simplified schematic of a still further system according to some embodiments.

[0020] FIG. 7 shows a simplified schematic of yet a further system according to some embodiments.

[0021] FIG. 8 shows a simplified schematic of yet a still further reactive distillation system according to some embodiments.

DETAILED DESCRIPTION

[0022] As used herein, the terms “temperature” may be abbreviated “T” and measured in “degrees Celsius” abbreviated as “°C”, “percent” may be abbreviated “%”, “weight” may be abbreviated “wt.”, “pressure” may be abbreviated “P” and measured in “bar gauge” abbreviated as “barg”, “atmosphere” and abbreviated as “atm”, or “pounds per square inch” and abbreviated as “psi”, “weight hourly space velocity” may be abbreviated “WHSV”, “hour” and “per hour” may be abbreviated, respectively, “h” and “h-1”, “minute” may be abbreviated “min”, “milliliter” may be abbreviated “mL”, and “milliliter” for gases normalized may be abbreviated “mL N”. Other abbreviations may be provided below.

[0023] A chemical manufacturing facility can include any suitable number of reaction and separation zones to undertake processes, e.g., to convert a feed into one or more products, and subsequently separate the product(s) for other components. One exemplary zone is a dehydrogenation zone that may include a reactor. Any suitable reactor may be utilized, such as a fixed bed reactor (e.g., a tubular reactor, packed bed, etc.) that can operate with gas or liquid phase reactants, although other types of reactors could be utilized such as a batch, a tubular reactor, or a fluidized bed reactor. Often, the reactor can contain a catalyst and be in a vapor phase. A vapor phase can mean one or more substances, such as the feed, in a gaseous phase.

[0024] Disclosed herein is a process for converting an alpha hydrogen alcohol such as ethanol into acetaldehyde and other products, including in some aspects, hydrogen. The resulting product blend can then be separated to produce a purified acetaldehyde product. The process can take place in a reactor over a catalyst, as described in more detail herein. The reaction can occur in the liquid or vapor phase, though in some embodiments, the reaction over the catalyst can occur in the vapor phase. The unreacted alcohol feed can be separated from the product stream and recycled to further convert the feed stream into products. In addition to acetaldehyde, other valuable byproducts can also be produced, and in some aspects, purified and sold as additional product streams, all as described in more detail herein.

[0025] One exemplary embodiment of a process and system 10 for the production of acetaldehyde is depicted in FIGS. 1-3. Referring to FIGS. 1-3, the system 10 can include an optional holding zone 20, an optional dehydration zone 40. a dehydrogenation zone 90, and a downstream separation section 110. The holding zone 20 can include suitable facilities for receiving feedstocks, such as any suitable alpha hydrogen alcohol, such as ethanol, from rail or barge. When a source of reactants is available other than as an individual shipment, the holding zone 20 can be absent from the system 10. The raw material may comprise only ethanol, which may present an advantage relative to other processes requiring multiple feedstocks. In addition, bio-derived ethanol may be used to allow the process to be operated from renewable ethanol sources. As an example only, at least one rail tank car 22 can communicate ethanol via one or more inlet lines 24 to any suitable number, e.g., one, two, or more, holding tanks, such as a first holding tank 26 and a second holding tank 28. The first and second holding tanks 26 and 28 can communicate via one or more outlet lines 30 to the dehydration zone 40.

[0026] A feed or first feed 42 from the holding zone 20 can be sent to the dehydration zone 40. When a continuous source of reactants such as a pipeline is available, the reactants can flow directly to the optional dehydration zone 40. In an embodiment, the ethanol feed 42 may comprise water. The presence of water in the ethanol feed 42 does not severely reduce the performance of the catalysts, which can tolerate up to 5% water by weight in the ethanol. Ethanol conversion is reduced when using an ethanol source with significant water content, but the reaction selectivity increases. The use of an ethanol feed comprising a small amount of water may be advantageous by allowing for the use a potentially less expensive ethanol source in the form of the ethanol/water azeotrope (about 4.4% water by weight). In some aspects, the water can be removed prior to producing acetaldehyde. This can help to reduce the amount of water that is removed in the downstream processing. When a feed having less than about 5 wt.%, less than about 4 wt.%, or less than about 3 wt.% water is available, the dehydration zone 40 may be absent from the system 10.

[0027] The feed or first feed 42 can be in fluid communication with a dehydration system configured to produce an ethanol stream having a water content below a desired concentration. The dehydration system can comprise any suitable units such as distillation units (e.g., extractive distillation, etc.), absorption units, adsorbent beds, extraction units, or the like. In some embodiments, one or more adsorbent beds can be used to dehydrate the ethanol stream. [0028] For example, the dehydration zone 40 may have a swing bed absorption or adsorption (hereinafter may collectively be referred to as absorber or absorption) reactors, such as a first swing bed reactor 44 and a second swing bed reactor 48 in a parallel configuration. The feed 42 can branch into a first feed line 46 and a second feed line 50 to communicate with respective first swing bed reactor 44 and second swing bed reactor 48. Each swing bed reactor 44 and 48 can contain an absorbent or an adsorbent, such as a zeolite. In operation, one swing bed reactor can be absorbing water from the feed 42 passing therethrough while the other swing bed reactor is being regenerated. When the bed is saturated, the beds can be reversed so that the regenerated bed can be used to adsorb water while the other bed is regenerated. When a bed is isolated for regeneration, the ethanol can be drained from the bed and passed back to the storage tanks for use within the system.

[0029] A regeneration zone 52 can provide a heated inert gas, such as nitrogen, via an inlet line 54 branching to each respective swing bed reactors 44 and 48 to pass through the nonoperating absorber, and after passing through the absorber, be communicated by an outlet line 58 merging to form a single line returning the regeneration gas back to the regeneration zone 52 for purification and optionally reuse and recovery⁷ of any ethanol and water to be transferred to any suitable utility via a wet ethanol line 60 and a desorbed water line 62. Turning back to the ethanol passing through the absorber, once dried, the feed 42 can exit an outlet line 64 and pass to a filter 70 for removing any particles, such as absorbent particles. The ethanol passing out of the sw ing beds can have a water content of less than about 0.5 wt. %, less than about 0.4 wt. %, less than about 0.3 wt %, or less than about 0.2 wt. % based on the total weight of the absorption effluent in the outlet line 64. Due to the operation being alternated between swing bed reactors 44 and 48, the dried feed 42 can pass into a surge drum 72 to provide a steady, dried reactor feed 88 to the dehydrogenation zone 90.

[0030] The dried reactor feed 88 can optionally pass through a series of pre-heating exchangers before reacting in the dehydrogenation zone 90. Within the reactor section, at least a portion of the ethanol in the feed can be converted to acetaldehyde. The reactions can occur in the presence of a catalyst to produce a reaction mixture. Any suitable reactor configurations can be used such as one or more reactors arranged in series and/or parallel. The reactors can comprise fixed bed reactors, tubular reactors, reactive distillation units, fluidized bed reactors, or any other reactors configured to contact the ethanol with the catalyst under conditions suitable for carrying the formation of acetaldehyde.

[0031] The series of preheat exchangers can be inside or outside the dehydrogenation zone 90. The preheat exchangers can include at least one preheat exchanger 76, 78 that can include a first preheat exchanger 76 and a second preheat exchanger 78. Any suitable heating fluid 82 can be used, such as another process stream, e.g., at least a part of a bottoms stream from a column or a stream exiting an exothermic reactor. Afterwards, the dried reactor feed 88 can pass a vaporizing exchanger 84 heated with any suitable medium, such as pressunzed steam.

[0032] The dehydrogenation zone 90 can include at least one heater 94 and at least one reactor 112, such as a first reactor 112, a second reactor 116, and a third reactor 120. The at least one heater 94 can include a first heater 94. a second heater 96, and a third heater 98, although any suitable number of heaters may be utilized. In some aspects, a pre-heater 84 can also be present. Although the pre-heater 84 is depicted outside the dehydrogenation zone 90, it should be understood that the pre-heater 84 can be within the dehydrogenation zone 90. Typically , the heaters are fired with natural gas or other suitable fuel, or may utilize pressurized steam (e.g., steam stream 92). As the dehydrogenation reaction is typically endothermic, heaters 94, 96, and 98 can be positioned, respectively, before the first reactor 112, the second reactor 116, and the third reactor 120. The first reactor 112, the second reactor 116, and the third reactor 120 may be, independently, a fixed reactor or other type of reactor. As such, a first reactor effluent 114 can be from the first reactor 112 provided to the second reactor 116, a second reactor effluent 118 from the second reactor 116 provided to the third reactor 120. and a third reactor effluent 122 from the third reactor 120 including a conversion product 124 or a dehydrogenation zone effluent 124 including acetaldehyde and ethanol.

[0033] While three heat-reactor pairs are shown in FIG. 1, only one heater-reactor pair, only two heater-reactor pairs, or more than three heater-reactor pairs can also be present. The number of reactors can be selected to provide a desired per pass conversion of the reactants while also allowing for different reaction conditions and catalysts to be present in each reactor. In addition, any number of reactor trains can be provided in parallel to allow for a desired reactant and product throughput for the system.

[0034] Although not wanting to be bound by theory, the reaction typically removes hydrogen from ethanol and converts at least a portion of the feed to acetaldehyde. The hydrogen may not be introduced separately from the feed to the dehydrogenation zone, and the reaction can be undertaken under any suitable conditions, such as the pressure in the dehydrogenation zone is up to about 50 bar, the temperature in the dehydrogenation zone is from about 100 °C to about 300 °C, and the liquid hourly space velocity in the dehydrogenation zone is from about 0.5 to about 10 hr¹ or about 0.5 to about 1.0 hr¹. In some aspects, the ethanol can be in the vapor phase and can be heated to a temperature of between about 200 °C to about 300 °C and to a pressure from about 1 to about 50 bar upon entry into the first reactor 112. In some embodiments, the temperature may be at least about 200 °C, about 210 °C, about 220 °C, about 230 °C, about 240 °C, about 250 °C, about 260 °C, about 270 °C, about 280 °C, or about 290 °C. In some embodiments, the temperature may be no more than about 290 °C, about 280 °C, 270 °C. 260 °C, about 250 °C, about 240 °C. about 230 °C, about 220 °C, or about 210 °C. In some embodiments, the temperature may be about 200 °C to about 220 °C, about 220 °C to about 240 °C, about 240 °C to about 260 °C, about 260 °C to about 280 °C, or about 280 °C to about 300 °C. In some embodiments, the pressure may be at least about 1 bar, about 10 bar. about 20 bar, about 30 bar, or about 40 bar. In some embodiments, the pressure may be no more than about 50 bar, about 40 bar, about 30 bar, about 20 bar, or about 10 bar. In some embodiments, the pressure may be about 1 bar to about 10 bar, about 10 bar to 20 bar, about 20 bar to about 30 bar, about 30 bar to about 40 bar, or about 40 bar to about 50 bar. The first reactor effluent 114 from the first reactor 112 can leave the first reactor 112 at a lower temperature such as between about 10 °C to about 30 °C lower than the inlet temperature of the first reactor 112, and at a slight pressure drop. The second heater 96 can then serve to reheat the effluent 114 from the first reactor 112 to the reaction temperature of between about 200 °C to about 300 °C. While two reactors are shown in series, one reactor or three or more reactors can be used in series with an inlet heater positioned upstream of each reactor. The dehydrogenation zone effluent 124 can be sent at “A”.

[0035] In some aspects, the system 10 can produce hydrogen as a co-product with acetaldehyde. The hydrogen can be used within the system, for example to hydrogenate byproducts, and/or removed from the system and sold. In some aspects, hydrogen can be produced in an amount of between about 0.5 mol H2 to about 1.0 mol H2 per mole of acetaldehyde produced.

[0036] Referring to FIGS. 2-3, the chemical manufacturing facility 10 can include the downstream separation section 1 10 to purify the acetaldehyde and optionally remove the hydrogen and additional reaction products as products from the system. The separation section 110 can also be used to provide a recycle stream to the dehydrogenation section 90 for further reaction. In some aspects, the separation section 110 can include one or more separator such as distillation columns, flash drums, and associated equipment. In the embodiment as shown in FIGS. 2 and 3, the separation section can comprise a distillation column 130, a condenser 134, a flash drum 138, a pump 144, a cold trap drum 150, a product trap drum 160. an ethanol recovery column 180, a condenser 184, and a reboiler 192. The condensers 134 and 184 and the trap drums 150 and 160 can use any suitable fluid for cooling, such as cooling water or a refrigerant, such as liquified ammonia or nitrogen. The reboiler 192 can use any suitable medium for heating, such as pressurized steam or a combustible fuel, such as natural gas.

[0037] Generally, the dehydrogenation zone effluent 124 or a distillation column feed 124 is provided to the distillation column 130. In some embodiments, the distillation column feed 124 can include no more than about 30 wt. %, or no more than about 29 wt. % acetaldehyde and at least about 65 wt. %, or at least about 69 wt. % ethanol, and no more than about 3.0 wt. % of at least one of hydrogen, ethylene, ethyl acetate, trans-crotonalde, /7-bulanol. 2- ethylhexanol, 1 -octanol, diiodosilane, water, or a combination thereof based on the total weight of the distillation column feed 124. The distillation column feed 124 can be at temperature of about 260 °C to about 300 °C and a pressure of about 40 to about 50 pounds per square inch gauge (psig). The vapor can pass out of the distillation column 130 as an overhead stream 132 including the majority of the acetaldehyde and a bottoms stream 170 comprising the majority of the ethanol and other heavy material, as discussed hereinafter. In some embodiments, the overhead stream 132 can include at least about 90 wt. %, at least about 95 wt. %, or at least about 99 wt. % acetaldehyde based on the total w eight of the overhead stream 132 and a temperature of about 55 °C to about 65 °C and a pressure of about 40 to about 50 psig.

[0038] The overhead stream 132 can pass to the condenser 134 using a cooling fluid such as cooling water or a refrigerant to form a condenser effluent 136 at a temperature of about - 10 °C to about 0 °C and a pressure of about 40 to about 50 psig, and then sent to the flash drum 138, containing distillate. The drum distillate 142 can be provide to a suction side of the pump 144. The discharge 158 of the pump 144 can be split into a distillate 148. having at least about 99.5 wt. % acetaldehyde based on the total w eight of the distillate 148 and a temperature of about -10 °C to about 0 °C and a pressure of about 45 psig to about 55 psig, sent to the product trap drum 160, and at least a portion of the distillate 146 can be refluxed back to the distillation column 130. The at least a portion 146 can include at least about 99 wt. % acetaldehyde based on the total weight of the at least a portion 146, and a temperature of about -10 °C to about 0 °C and a pressure of about 45 to about 55 psig.

[0039] Turning back to the distillate flash drum 138, a vent gas stream 140 including lighter gases can pass through the condenser 156, and then be sent to the cold trap drum 150, which may have a jacket with a cooling fluid, such as a refrigerant for condensing most gases in the vent except gases requiring, e.g., cryogenic temperatures, to condense to a liquid state. The vent gas stream 140 can include at least about 30 wt. % hydrogen, at least about 4 wt. % ethylene, and at least about 64 wt. % ethyl acetate based on the total weight of the vent gas stream 140, and a temperature of about - 10 °C to about 0 °C and a pressure of about 45 psig to about 55 psig. A cold trap vent 152 can exit the top of the cold trap drum 150 and have at least about 75 wt. % hydrogen, at least about 10 wt. % ethylene, and at least about 10 wt. % acetaldehyde based on the total weight of cold trap vent 152, and a temperature of about -60 °C to about -40 °C and a pressure of about 45 psig to about 55 psig. The cold trap vent 152 can pass out of the system as a hydrogen product stream.

[0040] A cold trap liquid 154 can exit the bottom of the cold trap drum 150 and be sent to the product trap drum 160. The cold trap liquid 154 can have at least about 99.5 wt. % acetaldehyde based on the total weight of the cold trap liquid 154 and a temperature of about - 60 °C to about -40 °C and a pressure of about 45 psig to about 55 psig. A product vent 162 can exit the top and a product stream 164, typically a liquid, can be wi th drawn from the bottom of the product trap drum 160. The product vent 162 can have at least about 32 wt. % hydrogen and at least about 56 wt. % acetaldehyde based on the total weight of the product vent 162, and about -15 °C to about -0 °C and a pressure of about 40 psig to about 50 psig. The product stream 164 can have at least about 99.5 wt. % acetaldehyde based on the total weight of the product stream 164 and be at a temperature of about -15 °C to about -0 °C and a pressure of about 40 psig to about 50 psig.

[0041] Turning to the bottoms stream 170, the bottoms stream 170 can be sent to the ethanol recovery column 180 as shown in FIG. 3. In some embodiments, the bottoms stream 170 can have at least about 80 wt. %, at least about 95 wt. %, or at least about 97 wt. % ethanol based on the total w eight of the bottoms stream 170 and a temperature of about 75 °C about 85 °C and about -5 psig to about 5 psig. The remainder can include no more than about 3 wt. % or no more than about 2 wt. % of at least one of acetaldehyde, ethyl acetate, trans-crotonalde, /7-butanol. 2-ethylhexanol, 1 -octanol, or a combination thereof based on the total weight of the bottoms stream 170. In some embodiments, the bottoms stream 170 can have a temperature of about 115 °C to about 125 °C, a pressure of about 40 to about 50 psig, a liquid actual density of about 43 pound per foot cubed (lb/ft³), a liquid viscosity of about 0.25 centipoise (cP), and a liquid vapor pressure of about 60 pound per square inch (psia).

[0042] Referring to FIG. 3. the bottoms stream 170 from FIG. 2 can be passed to the ethanol recovery column 180. An ethanol recovery overhead stream 182 including ethanol, such as at least about 90%, at least about 95%, or at least about 97%, by weight, ethanol based on the total weight of the ethanol recovery overhead stream 182, can exit the top of the ethanol recovery column 180 and pass through the condenser 184 and split into a reflux 186 back to the ethanol recovery column 180 and a product as an ethanol stream 188. The ethanol stream 188 has at least about 90 wt. %, at least about 95 wt. %, or at least about 97 wt. % ethanol, at least about 1.0 wt. % acetaldehyde, and at least about 0.5 wt. % ethyl acetate based on the total weight of the ethanol stream 188, and a temperature of about 75 °C to about 85 °C and a pressure of about -5 psig to about 5 psig. An ethanol recovery bottoms stream 190 can be separated and include ethanol and one or more CT hydrocarbons. Typically, the ethanol recovery bottoms stream 190 includes at least about 85%, by weight, ethanol and no more than about 15%, by weight, one or more CT hydrocarbons based on the total weight of the ethanol recovery bottoms stream 190. The one or more CT hydrocarbons can include at least one of trans-crotonalde. /?-butanol. 2-ethylhexanol. 1 -octanol, or a combination thereof. The ethanol recovery bottoms stream 190 can be sent through a reboiler 192 with a portion sent back to the ethanol recovery⁷ column 180 as a boil-up stream 194 including one or more gases with the remainder recovered as an ethanol heavies stream 196. The ethanol heavies stream 196 can include at least about 85 wt. % ethanol, at least about 2 wt. % trans-crotonalde, at least about 4 wt. % w-butanol, at least about 2 wt. % 2-ethylhexanol, and at least about 2 wt. % diiodosilane based on the total weight of the ethanol heavies stream 196 and a temperature of about 75 °C to about 85 °C and a pressure of about -5 psig to about 5 psig.

[0043] The systems and methods of some embodiments provide a system in which ethanol may be the sole or primary component of the feed. Reference to a "single feed" to a reactive distillation column means that the column has only one chemical feed stream supplying intended reactant(s) to the column. Nonetheless, such a single feed distillation column may have multiple entry points for the reactant, or recycling feed streams where a part of the reactant liquid or a partial distillate is drawn from the column and fed back into the column at a different point, e.g., to achieve improved separation and/or more complete reaction. 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 distillation column refers to two separate chemical feed streams. Although not being want to be bound by theory, the primary and desired reaction is the conversion of ethanol to acetaldehyde with release of two hydrogen atoms. As an example, a single ethanol molecule can be subject to a dehydrogenation reaction to produce a reaction product of two hydrogen atoms and acetaldehyde, which results in the release of one mole of hydrogen per mole of ethanol reacted or acetaldehyde produced. Thus, the present invention provides systems and methods for the production of acetaldehyde from ethanol which includes reacting ethanol over a suitable dehydrogenation catalyst in a reactor, thereby producing acetaldehyde and hydrogen.

[0044] In some embodiments, a reactive distillation system can be used with the catalyst described herein to convert ethanol to acetaldehyde. The term "reactive distillation column" is used conventionally to refer to a distillation column in which both reaction and separation is performed as well as a distillation column in fluid communication with a reactor vessel where the separation of the products occurs simultaneously with the production of the products in the reactor. In some embodiments, a single reactive distillation column can be used. Hydrogen gas can be removed (e g., continuously) from the top of the reactive distillation column as an overhead stream. The majority of the acetaldehyde produced can be removed (e.g., continuously) from the bottom of the column as a bottoms stream. Optionally, contaminating byproducts present following reaction of the ethanol over the dehydrogenation catalyst can be reacted over a suitable hydrogenation catalyst in the lower part of the column or in a separate hydrogenation reactor. The hydrogenation can convert difficult to separate byproducts into species which are easier to separate from the acetaldehyde. Consequently, the process can also include purifying the acetaldehyde by distilling out resulting hydrogenated byproducts.

[0045] In an embodiment, the reactive distillation column is configured for the dehydrogenation of ethanol with the formation of acetaldehyde. The reaction is accomplished by passing the ethanol feed stream over a dehydrogenation catalyst, including any of those described herein, under suitable conditions.

[0046] In an embodiment of a reactive distillation column, a reactive distillation column containing an optional catalyst 217 with a feed of ethanol as shown schematically in FIG. 4 can produce hydrogen as a distillate and acetaldehyde as a bottoms product. The reactive distillation column 210 contains a generally central catalyst zone 212, and usually will include a top stage or non-reactive rectifying section 213 and a bottom state or non-reactive stripping section 215. Ethanol feed 214 is commonly fed to the middle part of the reactive distillation column. Distillate removed at the top of the column is passed through a partial condenser 216, and hydrogen is separated from lower boiling constituents in reflux tank 218. The condensed lower boiling constituents (i.e., reflux), or at least some portion thereof, can be cycled back to the column for further reaction and/or separation. The bottoms product can be passed through reboiler 220, where a portion of the bottoms product is evaporated and added back to the bottom of the column. The remaining bottoms product may pass out of the system as product stream 222. In some embodiments, only a portion of the bottoms product may be passed through reboiler 220, with the vapor portion passing back to the bottom of the column and the remainder of the bottoms product being combined with any bottoms product bypassing the reboiler 220 and passing out of the system as product stream 222 for further processes and/or use as a final product. The product stream 222 may comprise the acetaldehyde produced in the column along wi th unreacted ethanol and potentially any side products produced by the reaction. The column reflux and reboil ratios can be controlled such that a purified acetaldehyde product can be obtained as the bottoms product. In an embodiment, the bottoms product stream 222 may comprise 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% acetaldehyde by weight. In some embodiments, acetaldehyde and hydrogen are boiled from top of the column, and ethanol is obtained from the bottom of the column.

[0047] During operation, the reactants and products flow through the reactor/column reacting and flashing along the length of the reactor/column. In an embodiment, the reaction of the reactants and/or products may occur in the catalyst zone 212, and the reactions may occur in the vapor and/or liquid phase. Specific catalysts useful in the reactive distillation systems and methods disclosed herein can include any of those disclosed herein. Acetaldehyde and hydrogen are produced due to the reaction over the dehydrogenation catalyst. The column 210 can be operated at any suitable pressure between about 1 atm and about 80 atm. In an embodiment, the column 210 may be operated at a pressure ranging from about 1 atm to about 5 atm, about 5 atm to about 10 atm, about 7 atm to about 12 atm, about 13 atm to about 15 atm, about 13 atm to about 20 atm, about 15 atm to about 20 atm, about 15 atm to about 30 atm, about 20 atm to about 30 atm. about 20 atm to about 50 atm, about 30 atm to about 40 atm. about 40 atm to about 50 atm, or about 50 atm to about 60 atm, about 60 atm to about 70 atm, about 60 atm to about 80 atm, or about 70 atm to about 80 atm. The temperature profile in the column is dictated by the mixture boiling point along the height of the column. In an embodiment the temperature within the column may range from about 100 °C to about 350 °C, alternatively about 150 °C to about 250 °C. The column 210 may comprise any number of stages equivalent to a number of theoretical stages sufficient to effect the reaction and separation of acetaldehyde to a desired purity. In an embodiment, the number of stages or the number of height equivalents of a theoretical plate (HETP) may range from about 1 to about 100, including for example from about 1 to about 10, about 10 to about 20, about 10 to about 50, about 20 to about 30, about 20 to about 70, about 30 to about 40, about 30 to about 50, about 30 to about 100, about 50 to about 70, about 50 to about 100, or about 70 to about 100. As described in more detail below, a relatively high conversion of ethanol to products can be achieved by the counter-current flow of reactants and products in addition to overcoming the reaction equilibrium by removal of products through the concurrent distillation within the column 210.

[0048] Alternatively, or in addition to the separators already described, the separator may be a phase separator, which is a vessel that separates an inlet stream into a substantially vapor stream and a substantially liquid stream, such as a knock-out drum, flash drum, reboiler, condenser, or other heat exchanger. Such vessels also may have some internal baffles, temperature control elements, and/or pressure control elements, but generally lack any trays or other A pe of complex internal structure commonly found in columns. The separator also may be any other type of separator, such as a membrane separator. In a specific embodiment, the separator is a knockout drum. Finally, the separator may be any combination of the aforementioned separators arranged in series, in parallel, or combinations thereof. In an embodiment, separator comprises a distillation column. Generally, the heat exchanger is a relatively simple device that allows heat to be exchanged between two fluids without the fluids directly contacting each other. Examples of suitable heat exchangers include, but are not limited to, shell and tube heat exchangers, double pipe heat exchangers, plate fin heat exchangers, bayonet heat exchangers, reboilers, condensers, evaporators, and air coolers. In the case of air coolers, one of the fluids comprises atmospheric air, which may be forced over tubes or coils using one or more fans.

[0049] In some embodiments, side reactors can be connected to a distillation column to increase the catalyst holdup for improved reactant conversion. The use of the side reactors coupled with the distillation column can be a form of reactive distillation as described herein. In the side reactor embodiment, the side reactor feed is withdrawn from the distillation column and the reactor effluent is returned back to the same column. In some embodiments, the side reactor feed can be withdrawn from the distillation column and passed to the separation system before a separated recycle stream (e.g., comprising unreacted ethanol) is returned to the feed of the distillation column and/or side reactor. An adequate amount of catalyst may be arranged in a side reactor system where traditional reactor types and catalyst structures can be used. Also, the reaction conditions within the side reactor such as temperature can be adjusted independently of those prevailing in the distillation column by appropriate heat exchange.

[0050] Schematics for a side reactor reactive distillation column with two feeds 246, 248 with a single catalyst 240 are shown in FIGS. 5-6. A single side reactor 294 is shown, however, multiple side reactors along the length of the reactive distillation column 250 can be used. FIG. 5 shows a configuration where the feed 293 to the side reactor 294 is bottom up and vapor phase. The outlet from side reactor 294 is stream 295 which is sent back to the distillation column 250 at any location in the column 250 above the location of feed 293. FIG. 6 shows a configuration where the feed 296 to the side reactor 297 is top down and liquid phase. The outlet from side reactor 297 is 298 which is sent back to the distillation column 250 at any location in the column 250 below the location of the feed 296. The side reactors 294 and 297 each contain catalyst for converting ethanol into acetaldehyde. Examples of suitable catalysts are described in more detail herein.

[0051] While illustrated as a bottom up vapor phase design and a top down liquid phase design in FIGS. 5-6, the side reactors 294, 297 may also operate bottom up using a liquid phase draw from the column 250 and top down using a vapor phase draw' from the column with the appropriate equipment such as pumps, compressors, valves, piping, etc. In an embodiment, the side reactors 294, 297 may be implemented as a single reactor vessel, or as a plurality of reactor vessels arranged in series and/or parallel. In an embodiment, a plurality of side reactors may be implemented as shown in FIGS. 5-6 along the length of the column as needed. In addition, the catalyst in both the column 250 and the side reactor 294 may convert ethanol into acetaldehyde, though the specific catalysts (e.g., catalyst compositions, catalyst forms, and/or catalyst component loadings) in each of the column 250 and the side reactor 294, 297 may be the same or different. Suitable catalysts for converting ethanol into acetaldehyde may be selected based on the expected operating conditions, which may vary between the column 250 and the side reactor 294, 297.

[0052] Schematics for a side reactor reactive distillation with two feeds 280, 282 and using two distinct catalyst zones 270, 276 are shown in FIGS. 7-8. A single side reactor is shown for each catalyst zone in the reactive distillation column, however, multiple side reactors along the length of the reactive distillation column can be used for each catalyst zone. FIG. 7 show s a configuration where the top zone feed 299 to the side reactor 300 is bottom up and vapor phase. The bottom zone feed 302 to another side reactor 303 is also bottom up and vapor phase. The outlet from side reactor 300 is the stream 301 which is sent back to the distillation column at any location in the column above the location of the feed 299. The outlet from the side reactor 303 is stream 304 which is sent back to the reactive distillation column at any location in the column above the location of feed 302. FIG. 8 shows a configuration where the top zone feed 305 to the side reactor 306 is top down and liquid phase. The bottom zone feed 308 to another side reactor 309 is also top down and liquid phase. The outlet from side reactor 306 is the stream 307 which is sent back to the reactive distillation column at any location in the column below the location of feed 305. The outlet from side reactor 309 is stream 310 which is sent back to the distillation column at any location in the column below the location of feed 308. Examples of suitable catalysts for side reactors 300 and 306 may include any of the dehydrogenation catalysts described in more detail herein. The use of two separate side reactors can allow for the catalyst composition and/or reaction conditions (e.g.. temperature, etc. to be different between the side reactors. Multiple side reactors can also allow for the catalyst to be changed in a side reactor without the need to stop production within the system. [0053] While illustrated as a bottom up vapor phase design and a top down liquid phase design in FIGS. 7-8, the side reactors 300, 303, 306, 309 may also operate bottom up using a liquid phase draw from the reactive distillation column and top down using a vapor phase draw from the column with the appropriate equipment such as pumps, compressors, valves, piping, etc. In an embodiment, the side reactors 300, 303, 306, 309 may be implemented as a single reactor vessel, or as a plurality of reactor vessels arranged in series and/or parallel. In an embodiment, a plurality of side reactors may be implemented as shown in FIGS. 7-8 along the length of the column as needed. In addition, the respective catalysts in both the column and the side reactors 300, 306 may convert ethanol into acetaldehyde, though the specific catalysts (e.g., catalyst compositions, catalyst forms, and/or catalyst component loadings) in each of the column and the side reactors 300, 306 may be the same or different. Suitable catalysts for converting ethanol into acetaldehyde may be selected based on the expected operating conditions, which may vary between the column and the side reactors 300, 306. Similarly, the respective catalysts in both the column and the side reactors 303, 309 may comprise hydrogenation catalysts, though the specific catalysts (e.g.. catalyst compositions, catalyst forms, and/or catalyst component loadings) in each of the column and the side reactors 303. 309 may be the same or different. Suitable hydrogenation catalysts may be selected based on the expected operating conditions, which may vary between the column and the side reactors 300, 306.

[0054] In some embodiments, there is a process for the production of acetaldehyde which comprises converting a C2 feedstock comprising ethanol to acetaldehyde in an acetaldehyde production zone by a procedure selected from: (i) dehydrogenation, (ii) oxidation, (iii) reaction with acetaldehyde, and (iv) oxidation to acetaldehyde. The C2 feedstock used can be ethanol which has been produced by hydration of ethylene, by the Fischer Tropsch process, or by fermentation of a carbohydrate source, such as starch. It may alternatively be a byproduct of another industrial process. It may contain, besides ethanol, minor amounts of w ater as well as small amounts of impurities resulting from byproduct formation during its synthesis. If the C2 feedstock includes recycled unreacted ethanol, then any by-products formed in the dehydrogenation step which are contained in the recycled ethanol will also contribute to the level of by-products present in the C2 feedstock. Impurities present in the C2 feedstock may include, for example, higher alcohols such as /7-propanol. iso-propanol, n-butanol and secpentanol; ethers, such as diethyl ether, and di-iso-propyl ether; esters, such as iso-propyl acetate, s-butyl acetate and ethyl butyrate; and ketones, such as acetone, butan-2-one, and 2- pentanone. At least some of these impurities can be difficult to remove from acetaldehyde, even when they are present in quantities as low as about 0. 1 mole (mol) % or less, by traditional distillation procedures because they have boiling points which are close to that of acetaldehyde and/or form constant boiling mixtures therewith.

[0055] In some embodiments, the C2 feedstock may be subjected to dehydrogenation. In this case the C2 feedstock can be converted to acetaldehyde by a dehydrogenation procedure which comprises contacting a vaporous mixture containing ethanol and hydrogen with a dehydrogenation catalyst in a dehydrogenation zone maintained under dehydrogenation conditions effective for dehydrogenation of ethanol to yield acetaldehyde. Typical dehydrogenation conditions include use of an ethanol: hydrogen molar ratio of from about 1 : 10 to about 1000: 1, a combined partial pressure of ethanol and hydrogen of up to about 50 bar (5 x 10⁶ Pa), and a temperature in the range of from about 100° C to about 260° C. Preferably the combined partial pressure of ethanol and hydrogen ranges from about 3 bar (3 x 10⁵ Pa) up to about 50 bar (5 x 10⁶ Pa), and is more preferably at least 6 bar (6 x 10⁵ Pa) up to about 30 bar (3 x 10⁶ Pa), and even more preferably in the range of from about 10 bar (10⁶ Pa) up to about 20 bar (3 x 10⁶ Pa), for example from about 12 bar (1.2 x 10⁶ Pa) to about 15 bar (1.5 x 10⁶ Pa).

[0056] Dehydrogenation is preferably conducted in the dehydrogenation zone at a temperature of from about 200 °C to about 250 °C, preferably at a temperature in the range of from about 210 °C to about 240 °C, even more preferably at a temperature of about 220 °C. The ethanol :hydrogen molar ratio in the vaporous mixture fed into contact with the dehydrogenation catalyst usually will not exceed about 400: 1 or about 500: 1 and may be no more than about 50: 1.

[0057] The dehydrogenation catalyst is desirably a catalyst containing copper, optionally in combination with chromium, manganese, aluminum, zinc, nickel, zirconium, calcium, silica, or a combination of two or more of these metals, such as a copper, manganese and aluminum containing catalyst. In some embodiments, the catalysts can include, before reduction, a copper oxide on an alumina, which may contain 8% by weight of the alumina. In the dehydrogenation step the rate of supply of the C2 feedstock to the dehydrogenation zone typically corresponds to an ethanol liquid hourly space velocity (LHSV) of from about 0.5 hr'¹ to about 10 hr¹ or about 0.5 hr¹ to about 1.0 hr¹.

[0058] Hydrogen is produced as a result of the dehydrogenation reaction and can be used as a product stream from the process. The hydrogen can be substantially pure hydrogen or can be in the form of a mixture with other gases that are inert to the C2 feedstock and to the dehydrogenation catalyst. Examples of such other gases include inert gases such as nitrogen, methane and argon.

[0059] In the dehydrogenation zone, side reactions may also occur, including formation of water. Side reactions that may release water as a by-product include formation of ketones, such as acetone and butan-2-one, and formation of ethers, such as diethyl ether.

[0060] A range of undesirable by-products may be present in the intermediate reaction product mixture, some of which would cause separation problems if the intermediate reaction product mixture were to be directly refined because their boiling points are close to that of acetaldehyde or because they form azeotropes with acetaldehyde whose boiling point is close to that of acetaldehyde. Such by-products may be present in the C2 feedstock or may be produced. In order to avoid problems due to the presence of such by-products in the distillation, even in amounts as small as about 0.1 mol % or less, e.g. about 0.01 mol % or less, the problematical by-products can be substantially removed as a result of a suitable processing step.

[0061] As disclosed herein, a dehydrogenation catalyst can be used with an alcohol reactant (e.g.. an alpha hydrogen alcohol such as ethanol) to produce acetaldehyde in a reaction step. The catalyst can comprise any suitable catalyst for forming acetaldehyde from an alcohol such as ethanol. In some aspects, the catalyst can include copper, chromium, manganese, aluminum, zinc, nickel, or a combination thereof in the form of at least one oxide; a copper oxide and a zinc or a zinc oxide; or consists of a copper oxide, a zinc oxide, and a support. In some embodiments, the catalyst can further include chromium, manganese, aluminum, zinc, nickel, zirconium, or a combination thereof or a support comprising alumina. Generally, such a catalyst can have an average bulk density of about 1.5 gram per milliliter (g/mL), a side crush strength of at least about 50 newtons (N), and a surface area of about 115 meter-squared per gram (m²/g).

[0062] Any of the materials useful as a dehydrogenation catalyst may be synthesized using a variety of methods. In some embodiments, the dehydrogenation 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., about three to about five hours) and then allowed to dry at a temperature of about 110 °C. The dried material may then be heated to about 200 °C to remove the nitrous oxide (NO_X) 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 per minute °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.

[0063] 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 co-impregnation 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 dned 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 some embodiments, 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 some embodiments, the wet-impregnation technique may be used to provide a catalyst having a copper weight loading ranging from about 0.5 wt. % to about 50 wt. % with one or more additional components having a weight loading between about 0. 1 wt. % to about 10 wt. %.

[0064] The dehydrogenation catalyst 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-iomzed water. The total metal concentration can vary and may generally be between about 1 molar (M) and about 3M. 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 (about 20 °C). The sodium hydroxide solution may generally have a concentration of about 4M, though other concentrations may also be used. 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 w et-impregnation technique. [0065] 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 some embodiments, 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 some embodiments, the co-precipitation technique may be used to provide a catalyst having a copper weight loading ranging from about 2 wt. % to about 80 wt. %, with one or more additional components having a weight loading betw een about 2 wt. % to about 40 wt. %. [0066] The resulting catalyst from either the wet-impregnation technique and/or the coprecipitation technique may be further treated prior to use in the dehydrogenation zone disclosed herein. In some embodiments, 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 some embodiments, the sodium carbonate solution may have a concentration of about 0.2M. The catalyst may then be filtered and allowed to dry at about room temperature. In some embodiments, the sodium carbonate may comprise from about 0.2 wt. % to about 3.0 wt. % of the catalyst after being contacted with the sodium carbonate solution.

[0067] 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 some embodiments, 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.

[0068] The catalyst can include copper, chromium, manganese, aluminum, zinc, nickel, or a combination thereof in the form of at least one oxide; a copper oxide and a zinc or a zinc oxide; or consists of a copper oxide, a zinc oxide, and a support. In some embodiments, the catalyst can further include chromium, manganese, aluminum, zinc, nickel, zirconium, or a combination thereof or a support comprising alumina. Further, the present system and method may utilize base-metal catalysts, which may be less expensive than the precious metal-based catalysts of other production routes.

[0069] Without intending to be limited by theory, it is believed that the production of hydrogen during the dehydrogenation reaction within the process may result in contact between the dehydrogenation 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.

where FACH represents the molar flow rate of acetaldehyde in the reactor effluent (e.g., the product stream comprising the ethyl acetate), and the remaining terms are the same as described above with respect to the conversion of ethanol. In an embodiment, the dehydrogenation catalyst described herein may be capable of achieving a conversion of ethanol in the dehydrogenation zone described herein of at least about 10%, at least about 20%, at least about 30%, or at least about 40%.

EXAMPLES

[0070] The embodiments 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

[0071] In this example, an eight channel reactor was used that allowed each channel to have a pre-heat zone, a reaction zone, and an outlet zone. Each channel has an internal diameter of 6 mm and was filled with 3-6 mL of catalyst to determine the performance and output. The gas phase operation proceeded with evaporation of the liquid feed stock. The feed stock used mostly pure ethanol or ethanol and water mixtures. Hydrogen was utilized as a feed component for selected screening conditions. The gas argon was used as an internal standard used upstream for online flow distribution. The temperature ranged from 200 °C to 445 °C. The pressure ranged from 0.5 to 1.7 bar gauge in the various tests. Multiple sets or runs were conducted at varying conditions. The data for the runs is listed in Table 1 below:

TABLE 1

*New catalyst in reactor

[0072] The catalyst used are indicated as catalyst 1, catalyst 2, etc. and are characterized by composition and amount used in Table 2 below.

TABLE 2

[0073] The results for each run with the catalyst 1 are shown in Table 3 below.

TABLE 3

[0074] The results for each run with the catalyst 2 are shown in Table 4 below.

TABLE 4

[0075] The results for each run with the catalyst 3 are shown in Table 5 below.

TABLE 5

[0076] The results for each run with the catalyst 4 are shown in Table 6 below.

TABLE 6

[0077] The results for each run with the catalyst 5 are shown in Table 7 below.

TABLE 7

[0078] Having described various systems and methods herein, certain embodiments can include, but are not limited to:

[0079] In a first embodiment, a process for dehydrogenating an alkanol, the process comprises: contacting a feed comprising ethanol with a catalyst comprising copper or a copper oxide in a dehydrogenation zone of a reactor to obtain a conversion product comprising acetaldehyde, wherein the dehydrogenation zone comprises a vapor phase. [0080] A second embodiment can include the process of the first embodiment, further comprising dehydrating the feed before introducing to the dehydrogenation zone.

[0081] A third embodiment can include the process of the first embodiment or the second embodiment, wherein a conversion of the ethanol is at least 30%.

[0082] A fourth embodiment can include the process of any of the proceeding embodiments, wherein the selectivity to the acetaldehyde is at least 50%.

[0083] A fifth embodiment can include the process of any of the proceeding embodiments, wherein the temperature in the dehydrogenation zone is from about 100 °C to about 300 °C.

[0084] A sixth embodiment can include the process of any of the proceeding embodiments, wherein the liquid hourly space velocity in the dehydrogenation zone is from about 0.5 hr¹ to about 10.0 hr¹.

[0085] A seventh embodiment can include the process of any of the proceeding embodiments, wherein the catalyst further comprises chromium, manganese, aluminum, zinc, nickel, zirconium, or a combination thereof.

[0086] An eighth embodiment can include the process of any of the proceeding embodiments, wherein the catalyst comprises copper, chromium, manganese, aluminum, zinc, nickel, zirconium, calcium, silica, or a combination thereof in the form of at least one oxide.

[0087] A ninth embodiment can include the process of any of the proceeding embodiments, wherein the catalyst further comprises a support comprising alumina.

[0088] A tenth embodiment can include the process of any of the proceeding embodiments, wherein the catalyst comprises a copper oxide and a zinc or a zinc oxide.

[0089] An eleventh embodiment can include the process of any of the proceeding embodiments, wherein the catalyst consists of a copper oxide, a zinc oxide, and a support.

[0090] In a twelfth embodiment, a process for separating acetaldehyde from ethanol comprises: contacting a feed comprising ethanol with a catalyst comprising copper or a copper oxide in a dehydrogenation zone of a reactor to obtain a conversion product comprising acetaldehyde and hydrogen, wherein the dehydrogenation zone comprises a vapor phase.

[0091] A thirteenth embodiment can include the process of the twelfth embodiment, wherein the feed comprises at least about 25%. by weight, acetaldehyde and at least about 65%. by weight, ethanol based on the total weight of the feed.

[0092] A fourteenth embodiment can include the process of the twelfth embodiment or the thirteenth embodiment, wherein the distillate comprises at least about 99%, by weight, acetaldehyde based on the total weight of the distillate. [0093] A fifteenth embodiment can include the process of any one of the twelfth embodiment to the fourteenth embodiment, wherein the bottoms stream comprises at least about 95%, by weight, ethanol based on the total weight of the bottoms stream.

[0094] A sixteenth embodiment can include the process of any one of the twelfth embodiment to the fifteenth embodiment, further comprising introducing at least a portion of the overhead stream to a cold trap to recover a liquid; and combining the liquid with the distillate.

[0095] A seventeenth embodiment can include the process of any one of the twelfth embodiment to the sixteenth embodiment, further comprising introducing the bottoms stream to an ethanol recovery column; separating an ethanol recovery overhead stream comprising ethanol; and separating an ethanol recovery bottoms stream comprising ethanol and one or more C4⁺ hydrocarbons.

[0096] An eighteenth embodiment can include the process of any one of the twelfth embodiment to the seventeenth embodiment, wherein the ethanol recovery overhead stream comprises at least about 97%, by weight, ethanol based on the total weight of the ethanol recovery overhead stream.

[0097] A nineteenth embodiment can include the process of any one of the twelfth embodiment to the eighteenth embodiment, wherein the ethanol recovery' bottoms stream comprises at least about 85%, by weight, ethanol and no more than about 15%, by weight, one or more C4⁺ hydrocarbons based on the total weight of the bottoms stream.

[0098] A twentieth embodiment can include the process of any one of the twelfth embodiment to the nineteenth embodiment, wherein the one or more C4⁺ hydrocarbons comprises trans-crotonalde, n-butanol, 2-ethylhexanol, 1 -octanol, or a combination thereof.

[0099] In a twenty first embodiment, a process for dehydrogenating an alkanol, the process comprises: contacting a feed comprising ethanol with a catalyst comprising copper or a copper oxide in a dehydrogenation zone of a reactor to obtain a conversion product comprising acetaldehyde, wherein the dehydrogenation zone comprises a vapor phase; introducing a dehydrogenation zone effluent comprising acetaldehyde and ethanol to a distillation column; separating an overhead stream comprising acetaldehyde; refluxing at least a portion of the overhead stream to the distillation column and recovering a distillate; and separating a bottoms stream comprising ethanol.

[00100] A twenty' second embodiment can include the process of the twenty first embodiment, wherein the dehydrogenation zone operates at any suitable processing conditions. [00101] A twenty third embodiment can include the process of the twenty first embodiment or the twenty second embodiment, further comprising dehydrating the feed before introducing to the dehydrogenation zone.

[00102] A twenty fourth embodiment can include the process of any one of the twenty first embodiment to the twenty third embodiment, wherein hydrogen is not introduced separately from the feed to the dehydrogenation zone.

[00103] A twenty fifth embodiment can include the process of any one of the tw enty first embodiment to the tw enty fourth embodiment, wherein the pressure in the dehydrogenation zone of up to about 50 bar.

[00104] A twenty sixth embodiment can include the process of any one of the twenty first embodiment to the twenty fifth embodiment, wherein the temperature in the dehydrogenation zone is from about 100 °C to about 300 °C.

[00105] A twenty seventh embodiment can include the process of any one of the twenty first embodiment to the twenty sixth embodiment, wherein the liquid hourly space velocity' in the dehydrogenation zone is from about 0.5 hr¹ to about 10.0 hr¹.

[00106] A twenty eighth embodiment can include the process of any one of the tw enty first embodiment to the twenty seventh embodiment, wherein the catalyst further comprises chromium, manganese, aluminum, zinc, nickel, or a combination thereof.

[00107] A twenty ninth embodiment can include the process of any one of the twenty first embodiment to the twenty eighth embodiment, wherein the catalyst comprises the copper, chromium, manganese, aluminum, zinc, nickel, zirconium, or a combination thereof in the form of at least one oxide.

[00108] A thirtieth embodiment can include the process of any one of the twenty first embodiment to the twenty ninth embodiment, wherein the catalyst further comprises a support comprising alumina.

[00109] A thirty first embodiment can include the process of any one of the tw enty' first embodiment to the thirtieth embodiment, wherein the catalyst comprises a copper oxide and a zinc or a zinc oxide.

[00110] A thirty second embodiment can include the process of any one of the tw enty first embodiment to the thirty' first embodiment, wherein the catalyst consists of a copper oxide, a zinc oxide, and a support.

[00111] A thirty third embodiment can include the process of any one of the twenty' first embodiment to the thirty second embodiment, wherein the dehydrogenation zone effluent comprises at least about 25%, by weight, acetaldehyde and at least about 65%, by weight, ethanol based on the total weight of the feed.

[00112] A thirty fourth embodiment can include the process of any one of the twenty first embodiment to the thirty third embodiment, wherein the distillate comprises at least about 99%, by weight, acetaldehyde based on the total weight of the distillate.

[00113] A thirty fifth embodiment can include the process of any one of the twenty first embodiment to the thirty fourth embodiment, wherein the bottoms stream comprises at least about 95%, by weight, ethanol based on the total weight of the bottoms stream.

[00114] A thirty sixth embodiment can include the process of any one of the twenty first embodiment to the thirty fifth embodiment, further comprising introducing at least a portion of the overhead stream to a cold trap to recover a liquid; and combining the liquid with the distillate.

[00115] A thirty’ seventh embodiment can include the process of any one of the twenty first embodiment to the thirty sixth embodiment, further comprising introducing the bottoms stream to an ethanol recovery column; separating an ethanol recovery overhead stream comprising ethanol; and separating an ethanol recovery bottoms stream comprising ethanol and one or more Ci hydrocarbons.

[00116] A thirty' eighth embodiment can include the process of any one of the twenty first embodiment to the thirty seventh embodiment, wherein the ethanol recovery overhead stream comprises at least about 97%, by weight, ethanol based on the total weight of the ethanol recovery overhead stream.

[00117] A thirty ninth embodiment can include the process of any one of the twenty first embodiment to the thirty eighth embodiment, wherein the ethanol recovery' bottoms stream comprises at least about 85%, by weight, ethanol and no more than about 15%, by weight, one or more Cty hydrocarbons based on the total weight of the bottoms stream.

[00118] A fortieth embodiment can include the process of any one of the tw enty first embodiment to the thirty ninth embodiment, wherein the one or more Cri hydrocarbons comprises trans-crotonalde, n-butanol. 2-ethylhexanol, 1 -octanol, or a combination thereof.

[00119] 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, Ru, 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*(R_u-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. As used herein, the term '‘and/or” can mean one, some, or all elements depicted in a list. As an example, “A and/or B” can mean A, B, or a combination of A and B. 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 What is claimed is:

1. A process for dehydrogenating an alkanol, the process comprising: contacting a feed comprising ethanol with a catalyst comprising copper or a copper oxide in a dehydrogenation zone of a reactor to obtain a conversion product comprising acetaldehyde, wherein the dehydrogenation zone comprises a vapor phase.

2. The process of claim 1, further comprising dehydrating the feed before introducing to the dehydrogenation zone.

3. The process of claim 1 , wherein a conversion of the ethanol is at least 30%.

4. The process of claim 1, wherein the selectivity to the acetaldehyde is at least 50%.

5. The process of claim 1, wherein the temperature in the dehydrogenation zone is from about 100 °C to about 300 °C.

6. The process of claim 1 , wherein the liquid hourly space velocity in the dehydrogenation zone is from about 0.5 hr¹ to about 10.0 hr¹.

7. The process of claim 1, wherein the catalyst further comprises chromium, manganese, aluminum, zinc, nickel, zirconium, calcium, silica, or a combination thereof.

8. The process of claim 1, wherein the catalyst comprises copper, chromium, manganese, aluminum, zinc, nickel, or a combination thereof in the form of at least one oxide.

9. The process of claim 1, wherein the catalyst further comprises a support comprising alumina.

10. The process of claim 1, wherein the catalyst comprises a copper oxide and a zinc or a zinc oxide.

11. The process of claim 1, wherein the catalyst consists of a copper oxide, a zinc oxide, and a support.

12. A process for separating acetaldehyde from ethanol, comprising: contacting a feed comprising ethanol with a catalyst comprising copper or a copper oxide in a dehydrogenation zone of a reactor to obtain a conversion product comprising acetaldehyde and hydrogen, wherein the dehydrogenation zone comprises a vapor phase.

13. The process of claim 12, wherein the feed comprises at least about 25%, by weight, acetaldehyde and at least about 65%, by weight, ethanol based on the total weight of the feed.

14. The process of claim 12 or claim 13, wherein the distillate comprises at least about 99%, by weight, acetaldehyde based on the total weight of the distillate.

15. The process of claim 12. wherein the bottoms stream comprises at least about 95%, by weight, ethanol based on the total weight of the bottoms stream.

16. The process of claim 12, further comprising introducing at least a portion of the overhead stream to a cold trap to recover a liquid; and combining the liquid with the distillate.

17. The process of claim 12, further comprising introducing the bottoms stream to an ethanol recovery column; separating an ethanol recovery overhead stream comprising ethanol; and separating an ethanol recovery bottoms stream comprising ethanol and one or more CT hydrocarbons.

18. The process of claim 12. wherein the ethanol recovery overhead stream comprises at least about 97%, by weight, ethanol based on the total weight of the ethanol recovery overhead stream.

19. The process of claim 12, wherein the ethanol recovery bottoms stream comprises at least about 85%, by weight, ethanol and no more than about 15%, by weight, one or more CT hydrocarbons based on the total weight of the bottoms stream.

20. The process of claim 12, wherein the one or more CT hydrocarbons comprises trans- crotonalde. /?-butanol. 2-ethylhexanol. 1 -octanol, or a combination thereof.