TW201311623A - Processes for increasing alcohol production - Google Patents

Abstract

A process for reducing ethyl acetate and/or diethyl acetal concentration of a crude ethanol product by hydrolysis is disclosed. A portion of the water is initially separated from the crude ethanol product in a first column residue. Ethyl acetate in the first column distillate is hydrolyzed to form additional ethanol and acetic acid. Product ethanol is recovered in a second distillation column preferably in a side stream and acetic acid is removed in the second column residue.

Description

Process to increase ethanol production

The present invention relates broadly to processes for producing alcohols, and in particular, the present invention broadly relates to a process for increasing ethanol production by hydrolyzing ester contaminants contained in crude ethanol to form additional ethanol.

Industrially used ethanol is produced in a conventional manner from organic raw materials such as petroleum, natural gas or coal, or from intermediates such as raw materials such as syngas, or from starch raw materials such as corn or sugar cane. Produced from cellulose raw materials. Conventional processes for producing ethanol from petrochemical feedstocks and cellulosic feedstocks include ethylene acid catalyzed hydration, methanol homologation, direct alcohol synthesis, and Fischer-Tropsch synthesis. The instability of petrochemical feedstock prices can cause fluctuations in the cost of producing ethanol in the traditional way, so as the price of raw materials rises, the demand for alternative sources of ethanol is increasing. The starch raw material and the cellulose raw material are converted into ethanol via fermentation. However, fermentation is usually used for consumer production of ethanol, which is suitable for use in fuel or humans. In addition, the fermentation and food sources of starch or cellulosic feedstock compete with each other, thus limiting the amount of ethanol produced for industrial applications.

The production of ethanol via reduction of alkanoic acids and/or other carbonyl containing compounds has been extensively studied, and various combinations of catalysts, supports and operating conditions have been mentioned in the literature. During the reduction of an alkanoic acid such as acetic acid, other compounds may form simultaneously with ethanol, or It is formed in a side reaction. These impurities impose limitations on the production and recovery of ethanol from the reaction mixture. For example, during the hydrogenation reaction, the esters are produced together with ethanol and/or water to form azeotropes, which are difficult to separate. Furthermore, when the conversion is incomplete, the unreacted acetic acid remains in the crude ethanol product, which must be removed to recover the ethanol.

European Patent EP 0 020 553 describes a process for converting hydrocarbons to ethanol which involves converting the hydrocarbons to acetic acid and hydrogenating the acetic acid to ethanol. The stream from the hydrogenation reactor is separated to provide an ethanol stream and a stream of acetic acid and ethyl acetate, and the stream of acetic acid and ethyl acetate is recycled to the hydrogenation reactor.

Therefore, there is still a need in the industry for an improved process for recovering ethanol from crude products obtained by reduction of alkanoic acids such as acetic acid and/or other carbonyl containing compounds. Further, it is also necessary to reduce the content of impurities which are formed as by-products in the hydrogenation reaction such as ester impurities.

The present invention is an improved process for recovering ethanol and an improved process for reducing the amount of impurities formed in the acetic acid hydrogenation process, particularly an improved process for reducing the ethyl acetate content formed. In a first embodiment, the invention is directed to a process for producing ethanol comprising the steps of: (a) hydrogenating acetic acid in the presence of a catalyst in a reactor to form a crude ethanol product; (b) In the first distillation column, at least a portion of the crude ethanol product is separated to form a first distillate comprising ethanol and ethyl acetate, and a first residue comprising acetic acid; and (c) in the second distillation column At least a portion of the first distillate is separated to produce a second distillate comprising ethyl acetate and a side stream comprising ethanol. In one aspect, the process of the present invention further comprises the step of hydrolyzing a portion of the ethyl acetate in the first distillate to form ethanol and acetic acid. Step (c) may additionally comprise forming a second residue comprising acetic acid.

In a second embodiment, the invention is directed to a process for producing ethanol comprising the steps of: (a) hydrogenating acetic acid in the presence of a catalyst in a reactor to form a crude ethanol product; (b) In the first distillation column, at least a portion of the crude ethanol product is separated to form a first distillate comprising ethanol and ethyl acetate, and a first residue comprising acetic acid; (c) hydrolyzing at least a portion of the ethyl acetate in an amount effective to form additional ethanol and additional acetic acid; and (d) separating at least a portion of the first distillate in the second distillation column, To generate a side stream comprising ethanol and a second residue comprising residual acetic acid.

In a third embodiment, the invention is directed to a process for producing ethanol comprising the steps of: (a) hydrogenating acetic acid in the presence of a catalyst in a reactor to form a crude ethanol product; (b) In the first distillation column, at least a portion of the crude ethanol product is separated to form a first distillate comprising ethanol, ethyl acetate and a small amount of acetic acid, and a first residue comprising acetic acid; (c) increasing the number An ethanol content and an acetic acid content in a distillate; and (d) separating at least a portion of the first distillate in a second distillation column to produce a second distillate comprising ethyl acetate, and A side stream containing ethanol. In one aspect, step (d) additionally comprises forming a second residue comprising acetic acid.

In a fourth embodiment, the present invention is directed to a process for purifying a crude ethanol product comprising ethanol, ethyl acetate and acetic acid, the process comprising the steps of: (a) in the first distillation column, the ethanol is coarse Separating at least a portion of the article to produce a first distillate comprising ethanol and ethyl acetate, and a first residue comprising acetic acid; and (b) in the second distillation column, the first distillate At least a portion is separated to produce a second distillate comprising ethyl acetate, a side stream comprising ethanol, and optionally a second residue comprising acetic acid. In one aspect, the process of the present invention further comprises hydrolyzing at least a portion of the ethyl acetate in the first distillate to form a hydrolyzed second distillate comprising ethanol and acetic acid prior to separating in step (b). .

preface

The present invention relates to a process for recovering ethanol which is optionally recovered from a crude ethanol product obtained by hydrogenating acetic acid in the presence of a catalyst. The crude ethanol product formed by the hydrogenation reaction may contain ethanol, water, ethyl acetate, unreacted acetic acid, and other impurities. The concentration of some of these compounds in the reaction mixture depends primarily on the catalyst for hydrogenation. Composition and process conditions. However, the water concentration in the reaction mixture is not subject to these factors because water is produced together with ethanol in a hydrogenation reaction at a molar ratio of about 1:1. Therefore, generating extra ethanol will also generate additional water.

In addition to water, the crude ethanol product formed by hydrogenation of acetic acid usually contains ethyl acetate (EtOAc) which is formed with water by an equilibrium reaction between ethanol (EtOH) and unreacted acetic acid (HOAc). The equilibrium reaction is as follows Shown.

Diethyl acetal (DEA) can also be formed from ethanol and acetaldehyde (AcH) together with water according to the following reaction.

The present invention advantageously reduces ethyl acetate and DEA levels in crude ethanol products and provides a low energy separation process for recovering ethanol products. In a preferred embodiment, the process comprises the steps of: (a) hydrogenating acetic acid in the presence of a catalyst in a reactor to form a crude ethanol product; (b) in the first distillation column, the ethanol is coarse At least a portion of the article is separated to produce a first distillate comprising ethanol, ethyl acetate and/or DEA, and a first residue comprising acetic acid; and (c) in the second distillation column, the first At least a portion of the distillate is separated to produce a second distillate comprising ethyl acetate, a side stream comprising ethanol, and optionally a second residue comprising acetic acid and/or DEA. Preferably, the process further comprises the step of hydrolyzing a portion of the ethyl acetate in the first distillate to form ethanol and acetic acid, thereby enhancing the overall selectivity of the ethanol. Additionally or alternatively, the process further comprises the step of hydrolyzing a portion of the DEA in the first distillate to form ethanol and acetaldehyde.

Hydrogenation of acetic acid

As defined herein, the process of the present invention can be utilized with any hydrogenation process used to produce ethanol or any other process for forming crude ethanol products. Materials, catalysts, reaction conditions, and separation processes available for the hydrogenation of acetic acid are further described below.

The raw materials used in the process of the present invention, acetic acid and hydrogen, may be from any suitable source, including Including natural gas, petroleum, coal, and raw materials. For example, acetic acid can be produced via methanolic carbonylation, acetaldehyde oxidation, ethylene oxidation, oxidative fermentation, and anaerobic fermentation. Methanol carbonylation processes suitable for the production of acetic acid are described in U.S. Patent Nos. 7,208,624, 7,115,772, 7,005,541, 6,657,078, 6,627,770, 6,143,930, 5,599,976, 5,144,068, 5,026,908, The entire disclosures of these patents are incorporated herein by reference. Optionally, ethanol production and such a methanol carbonylation process can be integrated.

As oil and natural gas become expensive due to price fluctuations, methods for producing acetic acid and intermediates such as methanol and carbon monoxide from alternative carbon sources have generated increasing interest. In particular, when petroleum is relatively expensive, syngas derived from other available carbon sources ("syngas") may be advantageous in the manufacture of acetic acid. For example, U.S. Patent No. 6,232,352 teaches a method of modifying a methanol plant to produce acetic acid, the entire disclosure of which is incorporated herein by reference. By modifying the methanol plant, significant capital expenditures for the production of carbon monoxide (CO) in the new acetic acid plant can be significantly reduced or significantly eliminated. All or part of the syngas is transferred from the methanol synthesis loop and fed to a separator unit to recover carbon monoxide, which is then used to produce acetic acid. In a similar manner, the syngas can provide hydrogen for the hydrogenation step.

In some embodiments, some or all of the feedstock used in the foregoing acetic acid hydrogenation process may be derived partially or completely from the syngas. For example, acetic acid can be formed from methanol and carbon monoxide, both of which can be derived from syngas. The syngas can be formed by partial oxidation reforming or steam reforming, and carbon monoxide can be separated from the syngas. Similarly, hydrogen for the step of hydrogenating acetic acid to form a crude ethanol product can be separated from the syngas. Syngas can be converted from a variety of carbon sources. For example, the carbon source may be selected from the group consisting of natural gas, petroleum, gasoline, coal, biomass materials, and combinations thereof. Syngas or hydrogen can also be derived from biologically derived methane gas, such as biosourced methane gas produced by landfills or agricultural waste.

In another embodiment, the acetic acid used in the hydrogenation step can be produced by fermentation of the biomass material. The fermentation process is preferably an acetic acid producing process or a homologous acetic acid producing microorganism. (homoacetogenic microorganism) Fermentation of sugar into acetic acid, if any, produces a small amount of carbon dioxide as a by-product. The carbon efficiency of the fermentation process is preferably higher than 70%, higher than 80% or higher than 90% compared to the conventional yeast process in which the carbon efficiency is usually about 67%. Optionally, the microorganism used in the fermentation process is a genus selected from the group consisting of Clostridium, Lactobacillus, Moorella, and Thermoanaerobacter. (Thermoanaerobacter), Propionibacterium, Propionispera, Anaerobiospirillum, and Bacteriodes, especially the species Choose from Clostridium formicoaceticum, Clostridium butyricum, Moorella thermoacetica, Thermoanaerobacter kivui, Lactobacillus Delbrukii), Propionibacterium acidipropionici, Propionispera arboris, Anaerobiospirillum succinicproducens, Bacteriodes amylophilus, and Bacteroides bacillus (Bacteriodes ruminicola) group of groups. In this process, all or a portion of the unfermented residue from the raw material, such as lignans, may optionally be gasified to form hydrogen for use in the hydrogenation step of the present invention. Exemplary fermentation processes for the formation of acetic acid are disclosed in U.S. Patent Nos. 6,509,180, 6,927,048, 7,074,603, 7,507,562, 7,351,559, 7,601,865, 7,682,812, and 7,888,082. All content is incorporated herein by reference. See also U.S. Patent Publication No. 2008/0193989 and No. 2009/0281354, the entire contents of each of which are hereby incorporated by reference.

Examples of biomass materials include, but are not limited to, agricultural waste, forest products, forage and other cellulosic materials, wood harvest residues, conifer wood shavings, hardwood shavings, tree branches, tree debris, leaves, bark, sawdust, Unqualified pulp, corn, corn stalks, straw, rice straw, bagasse, switchgrass, miscanthus, animal fertilizer, municipal waste, municipal sewage, commercial waste, grape skin, almond shell, pecan shell, coconut shell, Coffee grounds, compressed hay, dried Forage, dry wood, cardboard, paper, plastic and clothing. See, for example, U.S. Patent No. 7,884,253, the entire disclosure of which is incorporated herein by reference. Another source of biomass is black liquor, a thick black liquid that is a by-product of the Kraft process used to convert wood into pulp, which is then dried. Into paper. Papermaking black liquor is an aqueous solution consisting of lignin residues, hemicellulose and inorganic chemicals.

U.S. Reissue Patent No. RE35,377, which is incorporated herein by reference, which is incorporated herein by reference in its entirety in its entirety in the the the the the the the the the the This process includes a process for hydrogenation of solid and/or liquid carbonaceous materials to obtain a process gas which is additionally subjected to steam pyrolysis of natural gas to form a synthesis gas. The syngas is converted to methanol and the methanol is carbonylated to acetic acid. This method also produces hydrogen, and hydrogen can be used in the present invention as described above. U.S. Patent No. 5,821,111 discloses a process for the conversion of waste biomass into a synthesis gas via gasification, and a method for producing a hydrogen-containing gas composition such as a synthesis gas containing hydrogen and carbon monoxide, as disclosed in U.S. Patent No. 6,685,754. The entire contents of the patent application are incorporated herein by reference.

The acetic acid fed to the hydrogenation reaction may also contain other carboxylic acids and anhydrides, as well as acetaldehyde and acetone. Preferably, a suitable acetic acid feed stream comprises one or more compounds selected from the group consisting of acetic acid, acetic anhydride, acetaldehyde, ethyl acetate, and mixtures thereof. These other compounds can also be hydrogenated in the process of the invention. In some embodiments, the presence of a carboxylic acid such as propionic acid or its anhydride may be advantageous for the production of propanol. Water may also be present in the acetic acid feed.

Alternatively, the acetic acid in vapor form can be removed directly from the flash column of the methanol carbonylation unit in the form of a crude product. The type of the methanol carbonylation unit is described in U.S. Patent No. 6,657,078, the entire disclosure of which is incorporated herein by reference. For example, a crude vapor product can be fed directly into the ethanol synthesis reaction zone of the present invention without the need to condense or remove water from the acetic acid and light ends, saving overall processing costs.

The acetic acid can be evaporated at the reaction temperature, and then the evaporated acetic acid is fed together with the undiluted state or hydrogen diluted with a relatively inert carrier gas such as nitrogen, argon, helium or carbon dioxide. for The reaction in the gas phase should be controlled to a temperature not lower than the acetic acid dew point. In one embodiment, acetic acid can be vaporized at a specific pressure at the boiling point of acetic acid, and then the evaporated acetic acid can be further heated to the reactor inlet temperature. In another embodiment, the acetic acid is first mixed with other gases and evaporated, and then the mixed gas is heated to the reactor inlet temperature. Preferably, the acetic acid is transferred to the vapor state by passing hydrogen and/or a recycle gas through the acetic acid at a temperature equal to or lower than 125 ° C, and then the combined gas stream is heated to the reactor inlet temperature.

Some process embodiments for the hydrogenation of acetic acid to ethanol may include the use of a variety of configurations with fixed bed reactors or fluidized bed reactors. In many embodiments of the invention, an "adiabatic" reactor can be used; that is, there is little or no need to heat or remove heat with an internal header within the reaction zone. In other embodiments, a radial flow reactor or reactor set can be used, or a series of reactors with or without heat exchange, annealing, or introduction of additional feed can be used. Alternatively, a shell and tube reactor provided with a heat transfer medium can be used. In many cases, the reaction zone can be housed in a single vessel or in a series of vessels with heat exchangers therebetween.

In a preferred embodiment, the catalyst is used in a fixed bed reactor, such as in a tube or tube, wherein the reactants, typically in vapor form, pass through the catalyst surface or interior. Other reactors may be employed, such as fluidized or bunk bed reactors. In some cases, the hydrogenation catalyst can be used in conjunction with an inert material to control the pressure drop of the reactant stream through the catalyst bed and the contact time of the reactant compound with the catalyst particles.

The hydrogenation reaction can be carried out in the liquid phase or in the gas phase. It is preferred to carry out the reaction in the gas phase under the following conditions. The reaction temperature may range from 125 ° C to 350 ° C, such as from 200 ° C to 325 ° C, from 225 ° C to 300 ° C, or from 250 ° C to 300 ° C. The pressure may range from 10 kilopascals (kPa) to 3,000 kilopascals, such as from 50 kilopascals to 2,300 kilopascals, or from 100 kilopascals to 1,500 kilopascals. The reactants may be fed into the reactor at a gas hourly space velocity (GHSV) of greater than 500 per hour, such as greater than 1,000 per hour, greater than 2,500 per hour, or even greater than 5,000 per hour of gas hourly space velocity. In terms of scope, GHSV can In the range of 50/hour to 50,000/hour, for example, 500/hour to 30,000/hour, 1,000/hour to 10,000/hour, or 1,000/hour to 6,500/hour.

The hydrogenation reaction is optionally carried out at a pressure just sufficient to overcome the pressure drop across the catalytic bed at the selected GHSV, although higher pressures are not inhibited, but it goes without saying that at, for example, 5,000/hour or 6,500 per hour A large pressure drop may be experienced through the reactor bed at high space velocities.

Although two moles of hydrogen are consumed per mole of acetic acid in the reaction to produce one mole of ethanol, the actual molar ratio of hydrogen to acetic acid in the feed stream may range from about 100:1 to 1:100. The change is, for example, 50:1 to 1:50, 20:1 to 1:2, or 12:1 to 1:1. Most preferably, the molar ratio of hydrogen to acetic acid is greater than 2:1, such as greater than 4:1 or greater than 8:1.

The contact or residence time can also vary widely, depending on the amount of acetic acid, catalyst, reactor, temperature and pressure. When a catalyst system other than a fixed bed is used, the typical contact time is in the range of less than 1 second to several hours, and at least for the gas phase reaction, the preferred contact time is 0.1 second to 100 seconds, for example. : 0.3 to 80 seconds or 0.4 to 30 seconds.

The hydrogenation reaction for forming acetic acid to ethanol is preferably carried out in the presence of a hydrogenation catalyst. Suitable hydrogenation catalysts include a catalyst comprising a first metal and optionally one or more second metals, a third metal or any number of other metals, optionally on a catalyst support. The first metal and optionally the second metal and the third metal may be selected from the group consisting of transition metals of Groups IB, IIB, IIIB, IVB, VB, VIB, VIIB, VIII, lanthanide metals, lanthanides or one selected from A metal of any of Groups IIIA, IVA, VA, and VIA. Preferred metal combinations in some exemplary catalyst compositions include platinum/tin, platinum/rhodium, platinum/rhodium, palladium/ruthenium, palladium/iridium, cobalt/palladium, cobalt/platinum, cobalt/chromium, cobalt/ruthenium, Cobalt/tin, silver/palladium, copper/palladium, copper/zinc, nickel/palladium, gold/palladium, rhodium/iridium and bismuth/iron. Exemplary catalysts are further described in U.S. Patent No. 7,608,744 and U.S. Patent Publication No. 2010/002999, the entire disclosure of which is incorporated herein by reference. In another embodiment, the catalyst comprises a Co/Mo/S catalyst, and this type of catalyst is described in U.S. Patent Publication No. 2009/0069, the entire disclosure of which is incorporated herein by reference.

In one embodiment, the catalyst comprises a first metal selected from the group consisting of copper, iron, cobalt, nickel, ruthenium, rhodium, palladium, iron, ruthenium, platinum, titanium, zinc, chromium, ruthenium, molybdenum, and tungsten. group. Preferably, the first metal is selected from the group consisting of platinum, palladium, cobalt, nickel and ruthenium. More preferably, the first metal is selected from the group consisting of platinum and palladium. In embodiments of the invention in which the first metal comprises platinum, it is preferred that the catalyst comprises less than 5% by weight platinum, such as less than 3% by weight or less than 1% by weight platinum, since platinum is expensive.

As noted above, in some embodiments, the catalyst can additionally comprise a second metal that typically acts as a promoter. If present, the second metal is preferably selected from the group consisting of copper, molybdenum, tin, chromium, iron, cobalt, vanadium, tungsten, palladium, platinum, rhodium, ruthenium, manganese, osmium, iridium, gold, and nickel. . More preferably, the second metal is selected from the group consisting of copper, tin, cobalt, rhodium, and nickel. Most preferably, the second metal is selected from the group consisting of tin and antimony.

In certain embodiments in which the catalyst comprises two or more metals, such as a first metal and a second metal, the first metal is present in the catalyst in an amount of from 0.1 to 10% by weight, such as from 0.1 to 5 weight. % or 0.1 to 3% by weight. The second metal is preferably present in an amount of from 0.1 to 20% by weight, such as from 0.1 to 10% by weight or from 0.1 to 5% by weight. For a catalyst containing two or more metals, the two or more metals may be alloyed with one another or may comprise a non-alloyed metal solution or mixture.

The preferred metal ratio may vary depending on the metal used in the catalyst. In some exemplary embodiments, the molar ratio of the first metal to the second metal is from 10:1 to 1:10, such as from 4:1 to 1:4, from 2:1 to 1:2, from 1.5:1 to 1:1.5 or 1.1:1 to 1:1.1.

The catalyst may also comprise a third metal selected from any of the metals listed above for the first metal or the second metal, as long as the third metal is different from the first metal and the second metal. In a preferred aspect, the third metal is selected from the group consisting of cobalt, palladium, rhodium, copper, zinc, platinum, tin, and antimony. More preferably, the third metal is selected from the group consisting of cobalt, palladium and rhodium. When present, the total weight of the third metal is preferably from 0.05 to 4% by weight, such as from 0.1 to 3% by weight or from 0.1 to 2% by weight.

In addition to one or more metals, in some embodiments of the invention, the catalyst further comprises a support or a modified support. The term "modified support" as used in this specification refers to a support comprising a support material and a support modifier which adjusts the acidity of the support material.

The total weight of the support or modified support is preferably from 75 to 99.9% by weight, such as from 78 to 97% by weight, or from 80 to 95% by weight, based on the total weight of the catalyst. In a preferred embodiment using a modified support, the support modifier is present in an amount of from 0.1 to 50% by weight, based on the total weight of the catalyst, for example from 0.2 to 25% by weight, from 0.5 to 15% by weight or 1 to 8 wt%. The metal of the catalyst may be dispersed throughout the support, laminated to the entire support, coated on the outer surface of the support (ie, the eggshell) or affixed to the surface of the support.

As is well known to those of ordinary skill in the art, the support material is selected to provide suitable activity, selectivity, and robustness to the catalyst system under process conditions used to form ethanol.

Suitable support materials may include support or ceramic support, such as based on a stable metal oxide. Preferred supports include ruthenium-containing supports such as ruthenium dioxide, ruthenium dioxide/alumina, Group IIA silicates such as calcium metasilicate, pyrogenic ruthenium dioxide, high purity ruthenium dioxide and the like. a mixture. Other supports may include, but are not limited to, iron oxide, aluminum oxide, titanium dioxide, zirconium oxide, magnesium oxide, carbon, graphite, high surface area graphitized carbon, activated carbon, and mixtures thereof.

As previously mentioned, the catalyst support can be modified by a support modifier. In some embodiments, the support modifier can be an acidic modifier that increases the acidity of the catalyst. Suitable acidic support modifiers may be selected from oxides of Group IVB metals, oxides of Group VB metals, oxides of Group VIB metals, oxides of Group VIIB metals, oxides of Group VIIIB metals , a group of alumina and a mixture of them. The acidic support modifiers include those selected from the group consisting of TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ . group. Preferred acidic support modifiers include those selected from the group consisting of TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and Al ₂ O ₃ . The acidic modifier may also include those selected from the group consisting of WO ₃ , MoO ₃ , Fe ₂ O ₃ , Cr ₂ O ₃ , V ₂ O ₅ , MnO ₂ , CuO, Co ₂ O ₃ and Bi ₂ O ₃ . group.

In another embodiment, the support modifier can be a low profile volatility or non-volatile alkaline modifier. For example, these basic modifiers may be selected from (i) alkaline earth metal oxides, (ii) alkali metal oxides, (iii) alkaline earth metal metasilicates, (iv) alkali metal metasilicates, v) a Group IIB metal oxide, (vi) a Group IIB metal metasilicate, (vii) a Group IIIB metal oxide, (viii) a Group IIIB metal metasilicate, and mixtures thereof Group of. In addition to oxides and metasilicates, other types of modifiers can be used, including nitrates, nitrites, acetates, and lactates. Preferably, the support modifier is selected from the group consisting of oxides and metasilicates of any of sodium, potassium, magnesium, calcium, strontium, barium, and zinc, and mixtures of any of the foregoing. More preferably, the alkaline support modifier is calcium citrate, especially calcium metasilicate (CaSiO ₃ ). If the alkaline support modifier comprises calcium metasilicate, it is preferred that at least a portion of the calcium metasilicate is in crystalline form.

A preferred ceria support material is the SS61138 high surface area (HSA) ceria catalyst carrier available from Saint-Gobain NorPro. Saint-Gobain NorPro SS61138 cerium oxide exhibits the following properties: contains about 95% by weight of high surface area cerium oxide; surface area of about 250 square meters per gram; median pore size of about 12 nanometers (nm); determined by mercury pore analysis The average pore volume is about 1.0 cubic centimeters per gram; and the packing density is about 0.352 grams per cubic centimeter (22 pounds per cubic inch).

A preferred ceria/alumina support material is a KA-160 (Sud Chemie) ceria sphere having a nominal diameter of about 5 mm, a density of about 0.562 g/cc, and an absorbance of about 0.583 g water/g support. The body has a surface area of about 160 to 175 square meters per gram, and a pore volume of about 0.68 milliliters per gram.

The catalyst composition suitable for use in the present invention is preferably formed by metal impregnation of the modified support, but other processes such as chemical vapor deposition may also be used. Such impregnation techniques are described in U.S. Patent Nos. 7,608,744 and 7, 863, 489, and U.S. Patent Publication No. 2010/0197485, the entire contents of each of which are incorporated herein by reference.

In particular, hydrogenation of acetic acid achieves the desired acetic acid conversion as well as the desired ethanol selectivity and yield. For the purposes of the present invention, the term "conversion" is used to mean the amount of a compound other than acetic acid that is converted to acetic acid in the feed. The conversion is expressed as the mole percent of acetic acid in the feed. The conversion can be at least 10%, such as at least 20%, at least 40%, at least 50%, at least 60%, at least 70%, or at least 80%. While a catalyst having a high conversion of at least 80% or at least 90% is desirable, in some embodiments, a low conversion can be accepted in the case of a high selectivity for ethanol. It is of course easy to understand that in many cases the conversion can be compensated by a suitable recycle stream or by using a larger reactor, but it is more difficult to compensate for the low selectivity.

"Selection rate" is expressed as the mole percent of acetic acid converted. It should be recognized that each of the compounds converted from acetic acid has an independent selectivity, and the selectivity is also independent of the conversion. For example, if 60% by mole of the converted acetic acid is converted to ethanol, we say the selectivity of ethanol is 60%. Preferably, the selectivity of the catalyst to ethoxylates is at least 60%, such as at least 70% or at least 80%. The term "ethoxylated compound" as used herein refers specifically to compounds such as ethanol, acetaldehyde and ethyl acetate. Preferably, the selectivity to ethanol is at least 80%, such as at least 85% or at least 88%. The preferred embodiment of the hydrogenation process also has a lower selectivity for undesirable products such as methane, ethane and carbon dioxide. The selectivity for these undesirable products is preferably less than 4%, such as less than 2% or less than 1%. It is better to present undetectable content for these unanticipated products. The alkane formation rate can be low, and ideally less than 2%, less than 1% or less than 0.5% of acetic acid is converted to alkanes by a catalyst, and alkanes are of little value other than as a fuel.

The term "yield" as used in this specification refers to the number of grams of a specific product such as ethanol formed per kilogram of catalyst per hour during hydrogenation. It is preferred to produce a yield of at least 100 grams of ethanol per kilogram of catalyst per hour, for example, a yield of at least 400 grams of ethanol per kilogram of catalyst per hour or a yield of at least 600 grams of ethanol per kilogram of catalyst per hour. . In terms of range, the yield is preferably from 100 to 3,000 grams of ethanol per kilogram of catalyst per hour, for example 400 to 2,500 grams per kilogram of catalyst per hour or 600 to per kilogram of catalyst per hour. 2,000 grams Ethanol.

Operating under the conditions of the present invention allows the production of ethanol to be at a level of at least 0.1 tons of ethanol per hour, such as at least 1 ton of ethanol per hour, at least 5 tons of ethanol per hour, or at least 10 tons of ethanol per hour. Depending on the scale, large-scale industrial production of ethanol should typically be at least 1 ton of ethanol per hour, such as at least 15 tons of ethanol per hour or at least 30 tons of ethanol per hour. In terms of scope, for large scale industrial production of ethanol, the process of the present invention can produce from 0.1 to 160 tons of ethanol per hour, such as from 15 to 160 tons of ethanol per hour or from 30 to 80 tons of ethanol per hour. The production of ethanol via fermentation, based on economic scale, generally does not allow the production of ethanol in a single unit, but can be achieved by the use of embodiments of the invention.

In various embodiments of the invention, the crude ethanol product produced by the hydrogenation process typically contains unreacted acetic acid, ethanol, and water prior to any subsequent processing, such as purification and separation. As used herein, the term "alcohol crude product" means any composition comprising 5 to 70% by weight of ethanol and 5 to 40% by weight of water. Exemplary compositional ranges for crude ethanol products are shown in Table 1. The "others" referred to in Table 1 may include, for example, esters, ethers, aldehydes, ketones, alkanes, and carbon dioxide.

The content indicated as below (<) in the tables of the entire specification of the present invention is preferably absent. If present, it may be present in minor amounts or may present a content greater than 0.0001% by weight up to a specific upper range limit.

In one embodiment, the crude ethanol product may comprise acetic acid in an amount of less than 20% by weight, such as less than 15% by weight, less than 10% by weight or less than 5% by weight of acetic acid. In embodiments having a low amount of acetic acid, the conversion of acetic acid is preferably greater than 75%, such as greater than 85% or greater than 90%. Further, the selectivity for ethanol may also be preferably high, and is preferably higher than 75%, such as higher than 85% or higher than 90%.

Hydrolysis and recovery of ethanol

The ethanol recovery process begins by introducing a crude ethanol product into an initial separation distillation column (first distillation column), and the first distillation column separates the crude ethanol product into a distillate comprising ethanol, ethyl acetate, and optionally DEA and water. And residues containing water and unreacted acetic acid. Preferably, most of the water from the crude ethanol product is separated in the residue (first residue) of the first distillation column, the state of the first distillation column being such that a sufficient amount of water enters the first distillate, For the hydrolysis of ethyl acetate and / or DEA. The water content of the first distillate is preferably provided in excess relative to the ethyl acetate content of the first distillate. In some preferred embodiments, the first distillate has a water: ethyl acetate molar ratio greater than 1:1, greater than 2:1, greater than 3:1, greater than 5:1, or greater than 10:1 . In some embodiments, additional water from the interior or exterior of the reaction system can be added to the first distillate to provide the desired ratio of water: ethyl acetate.

In a theoretical embodiment where ethanol and water are the sole products of the hydrogenation reaction, the crude ethanol product will comprise 71.9% by weight of ethanol and 28.1% by weight of water. However, not all of the acetic acid fed into the hydrogenation reactor is typically converted to ethanol. Subsequent reactions of ethanol, such as esterification, may form other by-products such as ethyl acetate. Thus, ethyl acetate is a by-product that reduces the ethanol yield in the process and increases the waste that must be removed by the system. According to a preferred embodiment of the present invention, the distillate (first distillate) from the first distillation column is introduced completely or partially into the hydrolysis unit, wherein ethyl acetate is contained (and/or DEA) is separately hydrolyzed to form ethanol and acetic acid or ethanol and acetaldehyde.

The esterification reaction to form ethyl acetate has a liquid phase equilibrium constant (K _est ) equal to 4.0 (see, for example, Witzeman and Agreda in, "Acetic Acid and its Derivatives," Marcel Dekker, NY, 1992, p. 271, The entire contents of this article are incorporated by reference. The hydrolysis reaction of ethyl acetate has an equilibrium constant K _hydrolysis of 0.25, which is the reciprocal of K _{esterification} .

Until the excess acetic acid that has not been converted to a product in the hydrogenation reactor is substantially removed from the crude ethanol product, such as in an acid separation column, the composition tends to esterify ethanol with acetic acid to form ethyl acetate and water. . In one embodiment of the invention, substantially all of the excess acetic acid is removed. The one or more derivative streams formed in the separation system may contain a small amount of acetic acid. Thus, any mixture of ethanol, ethyl acetate, and water in the derivatized stream is not in a chemically equilibrium state and is thermodynamically prone to hydrolysis of ethyl acetate.

In one embodiment, as described above, the ethyl acetate (and/or DEA) in the first distillate is hydrolyzed to reduce their concentration to form additional ethanol and acetic acid (either ethanol and acetaldehyde). The first distillate preferably comprises ethanol, ethyl acetate and water, wherein the water content is effective for hydrolyzing ethyl acetate. Optionally, additional water can be added to the first distillate as needed to achieve the desired ratio of water: ethyl acetate. In addition, although the present invention contemplates that the water concentration of the first distillate may be preferably increased when some embodiments are performed, the first distillate preferably contains substantially no acetic acid, such as less than 1% by weight or Less than 0.5% by weight of acetic acid. Allowing more water to enter the first distillate may result in an increase in acetic acid remaining in the first distillate due to the difficulty in separating the water from the acetic acid. In any event, the first distillate preferably comprises no more than 3% by weight acetic acid or no more than 2% by weight acetic acid.

Although ethyl acetate can be hydrolyzed in the absence of a catalyst, it is preferably applied. The medium is used to increase the reaction rate. The hydrolysis reaction of ethyl acetate can be carried out in a liquid phase or a gas phase. In one embodiment, the hydrolysis reaction of ethyl acetate is continuously carried out in a liquid phase.

According to an embodiment of the invention, the first distillate is passed through a hydrolysis unit comprising an ion exchange resin reaction bed. The ion exchange resin reaction bed may comprise a strongly acidic heterogeneous or homogenous catalyst such as Lewis acid, a strongly acidic ion exchange catalyst, an inorganic acid, and methanesulfonic acid. Exemplary catalysts include Amberlyst ^TM 15 [Rohm and Haas Company (Rohm and Haas Company), Philadelphia , USA ^{], Amberlyst TM 70, Dowex-M} -31 [The Dow Chemical Company (Dow Chemical Company)], Dowex Monosphere M -31 (Dow Chemical Company) and Purolite CT type catalyst [Purolite International SRL]. The ion exchange resin reaction bed is preferably a gel type or a marco-reticular reaction bed. The ion exchange resin reaction bed can be located outside of the distillation column or inside the distillation column. The effluent from the ion exchange resin reaction bed can be returned directly or indirectly to a separation system, preferably a return water removal unit or a second distillation column, as described hereinafter. The hydrolysis step can be carried out in the liquid phase or in the gas phase.

In one embodiment, the hydrolysis unit is housed in the first distillation column, while in other embodiments, the hydrolysis unit may be disposed separately from the first distillation column. Thus, the first distillation column may comprise a hydrolysis zone, preferably the hydrolysis zone is located at the top of the first distillation column or near the top of the first distillation column. The hydrolysis section can comprise an internal ion exchange resin reaction bed. In another embodiment, the hydrolysis section is an enlarged portion of the first distillation column, that is, it has a larger cross-sectional diameter than the lower half of the first distillation column. This structure can increase the residence time of the low boiling point material in the distillation column to promote further hydrolysis of the ethyl acetate.

In one embodiment of the invention, other compounds may also be hydrolyzed with ethyl acetate, such as diethyl acetal (DEA).

After the hydrolysis step, water is then optionally removed from the resulting stream to form an ethanol mixture stream, preferably comprising less than 10% by weight water, less than 6% by weight water or less than 4 % by weight of water. In terms of ranges, the ethanol mixture stream may comprise from 0.001 to 10% by weight water, such as from 0.01 to 6% by weight water or from 0.1 to 4% by weight water. Subsequently by B The alcohol mixture stream is recovered to obtain an ethanol product.

The water removal step should be carefully chosen because water and ethanol form an azeotrope that is not easily separated in the distillation column. The ethanol-water azeotrope limits the recoverable ethanol in the conventional distillation column to an ethanol product comprising about 92-96 wt% ethanol. Regardless of the presence of other compounds, the formation of such an azeotrope in a distillation column requires considerable energy. The present invention relates to the use of lower energy in a first distillation column than is required to produce an azeotrope such that a portion of the water is passed to the top of the column to enter the first distillate. After hydrolyzing ethyl acetate and/or DEA, the residual water contained in the distillate can then be removed from the first distillate using a water separator. This is advantageous in that the energy required is comparable to The water/ethanol azeotrope is required to be lower in the distillation column. Accordingly, the present invention is directed to (i) reducing the concentration of ethyl acetate and/or DEA in the first distillate, (ii) increasing the overall selectivity of ethanol, and (iii) dehydrating the crude ethanol product to remove the formation with ethanol. The water provides a low energy means.

The water concentration of the first distillate after the hydrolysis step may vary depending on the acetic acid conversion and the amount of ethyl acetate contained in the first distillate prior to the hydrolysis step. In one embodiment, the first distillate comprises a water content greater than the water content of the ethanol/water azeotrope, such as a water content of greater than 4% by weight, greater than 5% by weight, or greater than 7% by weight. In terms of ranges, the first distillate optionally comprises a water content of from 4% to 38% by weight, such as from 7% to 32% by weight or from 7% to 25% by weight. As discussed above, the water content is preferably sufficient to hydrolyze ethyl acetate and/or DEA contained in the first distillate, and preferably in the first distillate in an amount sufficient to provide water: acetic acid The molar ratio of ethyl ester is greater than 1:1, greater than 2:1, greater than 3:1, greater than 5:1, or greater than 10:1.

Since the water concentration in the first distillate is generally higher than the water content acceptable for industrial or fuel grade ethanol applications, the process in one embodiment of the invention involves removing a substantial portion of the water from the first distillate. Preferably, the removal is carried out after the hydrolysis step to form an ethanol mixture. Preferably, the water is removed first, and any appreciable amount of organic matter, such as acetaldehyde, is separated. In one embodiment, the first distillate is condensed by first removing water. For example, the first distillate in the gas phase can be fed into an adsorption unit comprising a molecular sieve or membrane. In some In an embodiment, the first distillate is condensed into a liquid and fed to the film. The first distillate is heated to evaporate water to allow water to pass through the membrane. In a preferred embodiment, at least 50% of the water in the first distillate is removed based on the total water content of the first distillate, for example at least 60% of the water or at least 75% of the water is removed. except. In a more preferred embodiment, from 90 to 99% of the water may be removed from the first distillate. Thus, the resulting ethanol mixture may comprise only 0.01 to 10% by weight of a small amount of water, for example 0.5 to 6% by weight or 0.5 to 4% by weight of water. Further, since ethyl acetate has been hydrolyzed, the resulting ethanol mixture preferably also contains only a small amount of ethyl acetate, for example, 0.1 to 50% by weight, 0.5 to 25% by weight or 1 to 15% by weight of acetic acid B. ester. If the ethanol mixture contains DEA, it preferably contains only a low amount of DEA, such as 10 wppm (ppm by weight) to 10,000 wppm, 25 to 5000 wppm or 50 to 1500 wppm of DEA. In one embodiment, the ethanol mixture comprises a water concentration that is lower than the water content of the ethanol/water azeotrope. In order to achieve a lower water concentration than the water content in the ethanol/water azeotrope, a large amount of energy is required. Thus, the present invention advantageously removes water from the first distillate after the hydrolysis step, thereby producing an ethanol mixture without the need to utilize a significant amount of energy. Furthermore, because the ethanol mixture contains less water, the need to remove water in subsequent product separation stages is also reduced.

The process of the present invention can remove water from the first distillate after the hydrolysis step using any suitable technique. For example, water can be removed in the gas phase, prior to condensation, or in the liquid phase. For example, the adsorption unit, membrane, molecular sieve, extraction column distillation, or a combination thereof can be used to remove water. Suitable adsorption units include pressure swing adsorption (PSA) units and thermal swing adsorption (TSA) units. The adsorption unit may comprise molecular sieves, such as aluminosilicate compounds.

It is also possible to use a single film or film array to separate water from the distillate. The film or film array can be selected from any suitable film that is capable of removing a permeate stream from a stream that also contains ethanol and ethyl acetate.

In an exemplary real-life mode, the energy demand of the first distillation column in the process of the present invention may be less than 5.5 million British thermal units (MMBtu) per ton of refined ethanol, such as per ton of refined ethanol. Less than 4.5 million British thermal units or less than 3.5 million British thermal units per ton of refined ethanol. In some embodiments, the process can operate with relatively high energy requirements, but the total energy demand is lower than the majority of the water in the crude ethanol product, such as more than 65% of the ethanol in the crude product, being transferred to the distillate. The energy needed.

The water removed from the first distillate after the hydrolysis step can be returned to the first distillation column and finally removed from the first distillation column via the first residue. In one embodiment, a portion of the removed water is condensed and returned to the lower portion of the ethanol distillation feed point of the first distillation column, such as near the bottom of the first distillation column. Depending on the water removal technique, there may be some ethanol and ethyl acetate in the removed water, so it may be desirable to recover these compounds by returning at least a portion of the removed water back to the first distillation column. Returning the removed water to the first distillation column increases the amount of water that is extracted and becomes a residue. In other embodiments, a portion of the removed water may be fed to a split distillation column, such as a second distillation column, preferably a second distillation column for recovering the ethanol product from the ethanol mixture. The presence of a small amount of water in the second distillation column, such as less than 10% by weight water based on the total feed, may be beneficial in promoting the hydrolysis of ethanol from, for example, acetic acid (which may be hydrolyzed by unreacted acetic acid and/or ethyl acetate). The other components which may be present in the ethanol mixture, such as ethyl acetate or residual acetaldehyde, are separated. If necessary, a part of the removed water can be blown off and the water removed from the system.

In a preferred embodiment, the second distillation column separates the ethanol product from the side stream and removes the acetic acid formed in the hydrolysis step via the residue (second residue). In some embodiments, the ratio of ethanol separated in the side stream to ethanol separated from the second residue is from 100:1 to 1:10, such as from 50:1 to 1:5 or 20:1. To 1:2. Any residual ethyl acetate and/or acetaldehyde (e.g., formed by hydrolysis of DEA) can be transferred to the second distillate of the second distillation column.

The ethanol mixture formed after the hydrolysis and preferably after the water removal step may enter the distillation column above or below the side of the ethanol product leaving the second distillation column. Feeding the ethanol mixture above the side stream into the second distillation column can cause acetic acid to enter the ethanol product (side stream). Conversely, adding the ethanol mixture to the second distillation column below the side stream can result in unreacted vinegar. Ethyl acetate enters the ethanol product.

All or part of the second distillate may be fed to the reactor or reaction zone to convert it to additional ethanol. Similarly, all or part of the second residue, particularly the acetic acid in the second residue, can be fed to the reactor or reaction zone to form additional ethanol. Additionally or alternatively, all or part of the second residue may be introduced into the first distillation column, while acetic acid may be recovered in the first residue in the first distillation column.

The ethanol mixture can be further processed in a second distillation column to recover the ethanol product. In some embodiments, it may be better to maintain the water concentration in the second distillation column. Depending on whether the first distillate is subjected to water separation, and if water separation is carried out, the ethanol mixture may comprise less than 0.5% by weight of water, depending on the type of water separator. To control the water concentration, the first distillate may be split by a by-pass line before or after the hydrolysis step, but preferably prior to the water removal step. The split ratio can be varied to control the water content of the second distillation column feed. In an embodiment, the split ratio may be in the range of 10:1 to 1:10, such as 5:1 to 1:5 or about 1:1. Other split ratios can also be used when controlling water concentration. The distillate in the bypass line is not separated and dewatered, and may be combined with the ethanol mixture or fed together into the second distillation column. The combined distillate and ethanol mixture may have an overall water concentration of greater than 0.5% by weight, such as greater than 2% by weight or greater than 5% by weight of the total water concentration. In terms of ranges, the total water concentration of the combined distillate and ethanol mixture may be from 0.5 to 15% by weight, such as from 2 to 12% by weight or from 5 to 10% by weight. Additional water from the second distillation column can be recovered in the second residue and/or ethanol side stream. As a result, it is possible to decide whether or not to separate residual water from the ethanol side stream depending on the intended use.

Figures 1 and 2 show an exemplary ethanol recovery system in accordance with an embodiment of the present invention. System 100 includes a reaction zone 101 and a separation zone 102. Hydrogen and acetic acid are fed into evaporator 110 via lines 104 and 105, respectively, to produce a vapor feed stream in line 111 and direct the vapor feed stream to reactor 103. In one embodiment, lines 104 and 105 can be combined and combined into evaporator 110. The temperature of the vapor feed stream in line 111 is preferably from 100 ° C to 350 ° C, such as from 120 ° C to 310 ° C or from 150 ° C to 300 ° C. As shown in Figure 1 It is shown that any feed that is not evaporated will be removed from the evaporator 110 and can be recycled or discarded. Further, although FIG. 1 shows that the line 111 communicates to the top of the reactor 103, the line 111 can be directed to the side, upper or bottom of the reactor 103. Further variations and other components of reaction zone 101 and separation zone 102 are described below.

The reactor 103 contains a catalyst for hydrogenating a carboxylic acid to ethanol, and is preferably a catalyst for hydrogenating acetic acid to ethanol. In one embodiment, one or more guard beds (not shown) may be used upstream of the reactor, optionally upstream of the evaporator 110, to protect the catalyst from contact to feed or return/re-feed. Toxic or unintentional impurities contained in the circulating stream. This guard bed can be used in a vapor or liquid stream. Suitable guard bed materials can include, for example, carbon, ceria, alumina, ceramics or resins. In one aspect, the guard bed media is functionalized, such as by silver, to capture specific species such as sulfur or halogen. In the hydrogenation process, a crude ethanol product stream is withdrawn from reactor 103 via line 112, preferably continuously withdrawn from reactor 103.

The crude ethanol product stream in line 112 can be condensed and fed into separator 106, which in turn provides vapor stream 113 and liquid stream 114. A suitable separator 106 includes a flash column or a knockout pot. The separator 106 can operate at a temperature of from 20 ° C to 250 ° C, for example, at a temperature of from 30 ° C to 225 ° C or from 60 ° C to 200 ° C. The pressure of the separator 106 can range from 50 kilopascals (kPa) to 2,000 kilopascals, such as from 75 kilopascals to 1,500 kilopascals or from 100 to 1,000 kilopascals. Optionally, the crude ethanol product in line 112 can be passed through one or more membranes to separate hydrogen and/or other non-condensable gases.

The vapor stream 113 exiting the separator 106 can comprise hydrogen and hydrocarbons which can be purged off and/or returned to the reaction zone 101. As shown, vapor stream 113 merges with hydrogen feed 104 and is fed together into evaporator 110. In some embodiments, the returned vapor stream 113 can be first compressed and then combined with the hydrogen feed 104.

The liquid stream 114 from the separator 106 is withdrawn and pumped to the sides of the distillation column 107. In one embodiment, the contents of the liquid stream 114 are substantially similar to the crude ethanol product obtained in the line 112 obtained by the reactor, except that the composition substantially excludes hydrogen, carbon dioxide, These components are preferably removed by separator 106 in addition to methane and/or ethane. Accordingly, liquid stream 114 can also be referred to as a crude ethanol product. Exemplary components of liquid stream 114 are shown in Table 2. It must be understood that the liquid stream 114 can contain other components not listed, such as components from the feed.

The "other esters" in Table 2 may include, but are not limited to, ethyl propionate, methyl acetate, isopropyl acetate, n-propyl acetate, n-butyl acetate or a mixture thereof. The "other ethers" in Table 2 may include, but are not limited to, diethyl ether, methyl ethyl ether, isobutyl ethyl ether or a mixture thereof. The "other alcohols" in Table 2 may include, but are not limited to, methanol, isopropanol, n-propanol, n-butanol or a mixture thereof. In one embodiment, liquid stream 114 may comprise propanol, such as isopropanol and/or n-propanol, in an amount of from 0.001 to 0.1% by weight, from 0.001 to 0.05% by weight, or from 0.001 to 0.03% by weight. It should be understood that these other ingredients may be carried by any distillate or residue stream described in this specification and will not be further described in this specification unless otherwise indicated.

Optionally, the crude ethanol product in line 112 or liquid stream 114 can be further fed to the ester. The reactor, the hydrogenolysis reactor or a combination thereof. An esterification reactor can be used to consume acetic acid in the crude ethanol product to further reduce the amount of acetic acid that needs to be removed. Although the use of a hydrolysis unit reduces the need for a hydrogenolysis unit as described herein, in embodiments in which a large amount of ethyl acetate is produced, hydrogenolysis can be used to convert ethyl acetate in the crude ethanol product to ethanol.

In the embodiment shown in Fig. 1, the line 114 is introduced into the intermediate portion of the first distillation column 107, for example, two quarters or three quarters. Depending on the composition of the crude ethanol product in line 114 and the operating conditions of first distillation column 107, first distillation column 107 separates the crude ethanol product in line 114 and preferably continuously separates it. The first distillate in line 117 and the first residue in line 116. In one embodiment, no entrainers are added to the first distillation column 107. The first distillate in line 117 contains ethanol, other organics, and water. The first residue in line 116 contains unreacted acetic acid, water, and possibly other heavy components. In some embodiments, particularly where the acetic acid has a high conversion of at least 80% or at least 90%, preferably a substantial portion of the water in the liquid stream 114, such as at least 35% to 90% water, Essentially all of the acetic acid is transferred together into the first residue.

When the distillation column 107 is operated at about 170 kPa, the temperature of the residue discharged into the line 116 is preferably from 90 ° C to 130 ° C, for example from 95 ° C to 120 ° C or from 100 ° C to 115 ° C. The temperature of the distillate discharged into the line 117 is preferably from 60 ° C to 90 ° C, for example from 65 ° C to 85 ° C or from 70 ° C to 80 ° C. In some embodiments, the pressure of the first distillation column 107 can range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa.

As previously mentioned, the first distillate in line 117 contains water and also contains ethanol and other organics such as ethyl acetate and/or DEA. In terms of ranges, the water concentration of the first distillate in line 117 is preferably from 4% to 38% by weight, such as from 7% to 32% by weight or from 7 to 25% by weight. As shown in Figure 1, prior to condensing the first distillate in line 117, the first distillate in line 117 is fed to hydrolysis unit 124, and ethyl acetate and water (preferably The reaction takes place in the hydrolysis unit 124 to form ethanol and acetic acid. As previously mentioned, the hydrolysis unit may comprise, for example, an ion exchange material or other material to catalyze the hydrolysis reaction. After hydrolysis, the resulting ethanol mixture is introduced into a water separator 118 to remove water. The water separator 118 can be an adsorption unit, a membrane, a molecular sieve, an extractive distillation column, or a combination thereof.

In a preferred embodiment, the water separator 118 is a pressure swing adsorption (PSA) unit. The PSA unit optionally operates at a temperature of from 30 ° C to 160 ° C, such as from 80 ° C to 140 ° C, and a pressure of from 0.01 kPa to 550 kPa, such as from 1 kPa to 150 kPa. The PSA unit can contain two to five beds. The water separator 118 can move at least 95% of the water from the first distillate in line 117 into the water stream 119, and more preferably from 99% to 99.99% water can be removed from the first distillate. All or a portion of the water stream 119 can be returned to the distillation column 107 where it is preferred that water is finally recovered from the distillation column 107 and enters the first residue in line 116. Additionally and alternatively, all or a portion of the water stream 119 may be purged by pipe 115. The remainder of the first distillate 117 is withdrawn from the water separator 118 to form an ethanol mixture stream 120. As shown, a portion of the first distillate in line 108 can be condensed and refluxed to first distillation column 107, for example, having a reflux ratio of from 10:1 to 1:100, such as from 2:1 to 1:50 or 1:1 to 1:10. The reflux ratio can vary with the number of stages, feed location, distillation column efficiency, and/or feed composition. Operating at a reflux ratio above 3:1 may be less desirable as more energy may be required to operate the first distillation column 107. Preferably, the ethanol mixture stream 120 does not return or reflux to the first distillation column 107. Optionally, as shown, a portion of the first distillate in line 108 is directed to second distillation column 109 to provide a limited amount of water, thereby promoting residual ethyl acetate in the second distillation column. Separated from ethanol in 109.

In another aspect, as shown in FIG. 1, all or a portion of the water in the water stream 119 is fed to the first portion below the point where the first distillate in the line 108 is refluxed to the first distillation column 107. Distillation column 107.

Exemplary components of the first distillate (before hydrolysis), ethanol mixture stream 120 (after hydrolysis and water removal), and the first residue in line 116 are shown in Table 3 below. In a preferred embodiment, the first distillate initially comprises at least 0.5% by weight ethyl acetate, for example at least 1% by weight or at least 2% by weight ethyl acetate, which may be hydrolyzed in the hydrolysis step. It should be understood that These streams may also contain other ingredients not listed, such as ingredients from the feed.

Some species, such as acetals, can be decomposed in the first distillation column 107 such that only very low or even unmeasurable amounts of acetals remain in the distillate or residue. Further, after the crude ethanol product leaves the reactor 103, the equilibrium reaction may occur between acetic acid and ethanol contained in the crude ethanol product or between ethyl acetate and water. Depending on the concentration of acetic acid in the crude ethanol product, this equilibrium reaction may drive the formation of ethyl acetate. The residence time and/or temperature of the crude ethanol product can be utilized and regulated in the hydrolysis unit 124 for this equilibrium reaction.

Depending on the water and acetic acid content contained in the residue of the first distillation column 107, the line 116 can be processed in one or more of the following processes. The following are exemplary processes for further processing of the first residue, it being understood that any of the following may be used regardless of the concentration of acetic acid. When the residue mainly comprises acetic acid, for example more than 70% by weight of acetic acid, the residue can be recycled to the reactor without separating the water. In one embodiment, when the residue primarily comprises acetic acid, such as greater than 50% by weight acetic acid, the residue can be separated into a flow of acetic acid and a stream of water. In some embodiments, acetic acid can also be recovered from the first residue having a lower concentration of acetic acid. The residue can be separated into acetic acid and water streams by a distillation column or one or more membranes. If a film or film array is used to separate the acetic acid from the water, the film or film array can be selected from any suitable acid resistant film capable of removing the permeate stream. The resulting acetic acid stream is optionally returned to reactor 103. The resulting water stream can be applied as an extractant, for example, sent to the second distillation column 109 via line 121 as described below, or the ester-containing stream can be hydrolyzed in a hydrolysis unit.

In other embodiments, for example, when the first residue in line 116 contains less than 50% by weight acetic acid, possible options include one or more of the following: (i) returning a portion of the residue to the reaction The vessel 103, (ii) neutralizes acetic acid, (iii) reacts acetic acid with an alcohol, or (iv) discards the residue in a wastewater treatment facility. The residue containing less than 50% by weight of acetic acid may also be separated using a weak acid recovery (WAR) distillation column to which a solvent (optionally as an entrainer) may be added. One case for this purpose exemplary solvents include ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, vinyl acetate, isopropyl ether, carbon disulfide, tetrahydrofuran, isopropanol, ethanol and C ₃ -C ₁₂ Alkanes. When the acetic acid is neutralized, it is preferred that the residue in line 116 contains less than 10% by weight acetic acid. The acetic acid can be neutralized using any suitable alkali or alkaline earth metal base such as sodium hydroxide or potassium hydroxide. When the acetic acid is reacted with an alcohol, it is preferred that the residue contains less than 50% by weight of acetic acid. The alcohol can be any suitable alcohol such as methanol, ethanol, propanol, butanol or a mixture thereof. The reaction forms an ester which can be combined with other systems such as carbonylation or ester production processes. Preferably, the alcohol comprises ethanol and the resulting ester comprises ethyl acetate. Optionally, the resulting ester can be fed to a hydrogenation reactor.

In some embodiments, when the first residue contains a very small amount of acetic acid, such as less than 5% by weight acetic acid, the residue can be disposed of in a wastewater treatment facility without further processing. The organic content of the residue, such as the acetic acid content, can be beneficial for feeding the microorganisms used in the wastewater treatment facility.

Returning to Fig. 1, the ethanol mixture stream 120 is introduced into the second distillation column 109, preferably into the upper portion of the distillation column 109, such as the upper half or one third of the upper portion. The second distillation column 109 may be a tray distillation column or a packed distillation column. In one embodiment, the second distillation column 109 is a tray distillation column having 5 to 70 trays, for example, having 15 to 50 trays or 20 to 45 trays. As an example, when a distillation column having 30 trays is used without a water extraction procedure, the ethanol mixture stream 120 is introduced to the tray 2.

Optionally, the second distillation column can be an extractive distillation column. Suitable extractants may include, for example, dimethyl hydrazine, glycerin, diethylene glycol, 1-naphthol, hydroquinone, N,N'-dimethylformamide, 1,4-butanediol, Ethylene glycol-1,5-pentanediol, propylene glycol-tetraethylene glycol-polyethylene glycol, glycerol-propylene glycol-tetraethylene glycol-1,4-butanediol, diethyl ether, methyl formate, cyclohexane, N , N'-dimethyl-1,3-propanediamine, N,N'-dimethylethylenediamine, diethylene triamine, hexamethylenediamine, and 1,3-diamine Alkylpentane, alkylated thiopene, dodecane, tridecane, tetradecane, chlorinated paraffin or a combination thereof. In another aspect, the extractant can comprise water. If the extractant comprises water, the extractant may be obtained from an external source or from an internal return/recycle line of one or more other distillation columns, such as water stream 119. In general, the extractant is fed into the ethanol mixture stream 120 for entry. Point, indicated by optional line 121. When an extractant is used, a suitable recovery system, such as another distillation column, can be employed to remove the extractant and recycle the extractant as needed.

The second distillation column 109 is operated to separate the ethanol mixture stream 120 or a portion thereof into a second distillate in line 123, a side stream 125 comprising an ethanol product, and a second residue in line 122. The second distillate in line 123 may comprise, for example, ethyl acetate and acetaldehyde, while the second residue comprises acetic acid formed by the hydrolysis of ethyl acetate. As previously mentioned, the second residue can be fed completely or partially to the reactor for conversion to additional ethanol or to the first distillation column. The side stream 125 comprises ethanol, which is optionally a finished ethanol product. If water is added to the second distillation column 109, the second residue 122 and/or the side stream 125 may contain some water, depending on the desired application of the ethanol product, an additional water removal step may be required.

Although the temperature and pressure of the second distillation column 109 may vary, the temperature of the second residue discharged into the line 122 is preferably from 30 ° C to 75 ° C at a pressure of from about 20 kPa to 70 kPa. For example, 35 ° C to 70 ° C or 40 ° C to 65 ° C. The temperature of the second distillate discharged into line 123 is preferably from 20 ° C to 55 ° C, such as from 25 ° C to 50 ° C or from 30 ° C to 45 ° C. The temperature of the side draw stream 125 is preferably from 30 ° C to 75 ° C, such as from 35 ° C to 70 ° C or from 40 ° C to 65 ° C. Distillation column 109 can be operated at low pressure or near or under vacuum to further promote the separation of ethyl acetate and ethanol. In other embodiments, the pressure of the second distillation column 109 is in the range of 0.1 kPa to 510 kPa, such as 1 kPa to 475 kPa or 1 kPa to 375 kPa. The exemplary distillate, side draw, and residue compositions of the second distillation column 109 are shown in Table 4 below. It will be appreciated that the second distillate, side stream and second residue may also contain other ingredients not listed, such as ingredients from the feed.

Preferably, the weight of the ethanol in the side draw relative to the ethanol in the second distillate is at least 2:1, such as at least 5:1, at least 8:1, at least 10:1 or at least 15:1. . The weight of ethyl acetate in the second residue relative to the ethyl acetate in the second distillate is preferably less than 0.4:1, such as less than 0.2:1 or less than 0.1:1.

The second distillate in line 123 comprises ethyl acetate and/or acetaldehyde, which is preferably refluxed as shown in Figure 1, for example, having a reflux ratio of 1:30 to 30:1, such as 1 : 15 to 15:1 or 1:5 to 5:1. In one aspect, the second distillate in line 123 or a portion thereof can be returned to reactor 103. For example, returning a portion of the second distillate 123 to the reactor 103 It can be advantageous. Ethyl acetate and/or acetaldehyde in the second distillate may be further reacted in the hydrogenolysis reactor 103 or in the second reactor. The effluent from the second reactor can be fed to reactor 103 to make additional ethanol, or fed to a distillation column, such as distillation column 115 or 109, to recover additional ethanol.

In the embodiment illustrated in Figure 1, the finished ethanol product produced by the process of the present invention can be taken from a side stream in line 125. Advantageously, a water separator and two distillation columns can be utilized in accordance with the present invention to recover the finished ethanol product. The finished ethanol product may be technical grade ethanol comprising from 75 to 96% by weight ethanol, such as from 80 to 96% by weight or from 85 to 96% by weight ethanol, based on the total weight of the ethanol product. An exemplary range of finished ethanol compositions is shown in Table 5 below.

The finished ethanol composition of the present invention preferably contains a very low amount, for example less than 0.5% by weight, of other alcohols such as methanol, butanol, isobutanol, isoamyl alcohol and other C ₄ -C ₂₀ alcohols. In one embodiment, the isopropanol content in the finished ethanol composition is from 80 to 1,000 wppm, such as from 95 to 1,000 wppm, from 100 to 700 wppm, or from 150 to 500 wppm. In one embodiment, the finished ethanol composition is substantially free of acetaldehyde, optionally comprising less than 8 wppm of acetaldehyde, such as less than 5 wppm or less than 1 wppm of acetaldehyde.

In some embodiments, when a further water separation means is used, the ethanol product can be withdrawn from the water separation unit as described above to become a stream. In these embodiments, the ethanol product may have an ethanol concentration greater than that shown in Table 5, and is preferably greater than 97% by weight ethanol, such as greater than 98% by weight or greater than 99.5% by weight ethanol. The ethanol product in this aspect preferably comprises less than 3% by weight water, such as less than 2% by weight or less than 0.5% by weight water.

In another embodiment of the present invention, as shown in Fig. 2, the first distillate in the line 117 is sent from the first distillation column 107 to the hydrolysis unit 124 to convert ethyl acetate and/or DEA into Ethanol and acetic acid or ethanol and acetaldehyde. The resulting stream is passed through a compressor 130 and fed into a membrane 131. Film 131 is preferably operated in the gas phase. Water in the first distillate in line 117 permeates through membrane 131 to form permeate stream 132. Permeate stream 132 can comprise at least 80% water from the first distillate, and preferably at least 90% water. In one embodiment, the permeate stream 132 also contains less than 10% ethanol from the first distillate, such as less than 5% ethanol. A portion of the permeate stream 132 can be returned to the distillation column 107, preferably from below the feed point of the liquid stream 114 to the distillation column 107. A portion of the permeate stream 132 can be purged from the system by blowing, as indicated by line 133, to control the amount of water in the distillation column 107.

The portion of the distillate that does not pass through the membrane 131 forms a netentate stream 134, such as an ethanol mixture stream, and is fed to the second distillation column 109 as shown in FIG. In one embodiment, the retentate stream 134 contains more water than the ethanol mixture stream composition shown in Table 3. For example, the cut-off stream 134 can comprise from 0 to 10% by weight water, and more preferably from 0 to 5% by weight water. The additional water present in the cut-off stream 134 facilitates the separation of ethyl acetate and ethanol in the second distillation column 109. The additional water fed into the second distillation column 109 is preferably removed with and/or moved into the side stream 125 with the second residue in the line 122, and a second dehydration step may be required as previously described. To obtain an ethanol product having a desired water concentration.

Although a single film is shown in Figure 2, it should be understood that a suitable film array can also be utilized.

In most embodiments of the invention, it is desirable to have the first distillate as shown in Figures 1 and 2. Remove water from the contents. In FIG. 3, the first distillate in line 117 is split into main line 140 and hydrolysis side line 144 after passing through hydrolysis unit 124. In an embodiment, the split ratio may be in the range of 10:1 to 1:10, such as 5:1 to 1:5 or about 1:1. The main line 140 is fed to the water separator 118 to form a water stream 142 and an ethanol mixture stream 143, and the hydrolysis side line 144 is introduced into the second distillation column 109. All or a portion of the water stream 142 can be returned to the first distillation column 107 as previously described in Figures 1 and 2. A portion of the first distillate in line 117 can be condensed and refluxed via line 108 to first distillation column 107, for example at 10:1 to 1:100, for example 2:1 to 1:50 or 1 : 1 to 1:10 reflux ratio is refluxed. Additional bypass line 141 may be fed to reflux line 108 and fed directly to second distillation column 109 along with ethanol mixture stream 143 and/or hydrolysis side line 144. A flow control valve (not shown) may be employed to control the split between the main line 140, the hydrolysis bypass line 144, and the additional bypass line 141 to feed the desired water concentration to the second distillation column 109. In one embodiment, a portion of the bypass line 141 is refluxed to the first distillation column 107 as shown. In another embodiment, the bypass line 141 is not returned to the first distillation column 107, and another separate return line (not shown) may be provided. A portion of the bypass line 141 can be condensed and fed separately to all or a portion of the ethanol mixture stream 143 to the second distillation column 109.

The separation of the first distillate 117 into the main line 140 and the side lines 141 and 144 can be controlled in accordance with the desired total water concentration of the streams 141, 143, 144. In one embodiment, the bypass line 141 contains a higher water concentration than the ethanol mixture stream 143 and the hydrolysis side stream 144. The total combined water concentration of streams 141, 143, 144 is optionally above 0.5% by weight, such as above 2% by weight or above 5% by weight. In terms of ranges, the overall water concentration of streams 141, 143, 144 can be from 0.5 to 15% by weight, such as from 2 to 12% by weight or from 5 to 10% by weight. The water content in the bypass line 141 can facilitate separation of ethanol from ethyl acetate in the distillation column 109. In another embodiment, additional water can be added to distillation column 109 via line 121. Optionally, the water portion of water stream 142 can be added to distillation column 109.

Each of the distillation columns shown in Figures 1 to 3 can be selected from any one capable of exhibiting a particular separation and/or Distillation column for the purification step. Each distillation column preferably comprises a tray distillation column having from 1 to 150 trays, for example from 10 to 100 trays, from 20 to 95 trays or from 30 to 75 trays. The tray can be a sieve tray, a fixed valve tray, a moving valve tray, or any other suitable design known in the art. In other embodiments, a packed distillation column can be used. In the case of a packed distillation column, a structured packing or a random packing can be used. These trays or packings may be arranged in a continuous distillation column or they may be arranged in two or more distillation columns such that the vapor enters the second stage from the first stage and the liquid is from the second stage Enter the first paragraph and so on.

For convenience, the distillate and residue of the first distillation column may also be referred to as "first distillate" or "first residue". Distillates or residues of other distillation columns may also be referred to by similar numerical modifiers (second, third, etc.) to distinguish one another, but such modifications are not to be construed as requiring any particular order of separation. Similarly, when the modifiers "first" and "second" are used to refer to a distillation column, it should be understood that this is used to distinguish the reactors, rather than requiring them to be the first or second distillation columns in the separation system, respectively. . For example, it is conceivable that the reaction crude product can be fed from a reactor or a flash unit to an initial separation unit such as a distillation column to form a crude ethanol product, which is then fed to the first and second of the present invention. The distillation column is processed.

The associated condenser and liquid separation tank that can be used in each distillation column can be of any conventional design and is simply illustrated in the drawings. Heat can be supplied to the base of each distillation column or to the bottom stream of the recycle via a heat exchanger or reboiler. Other types of reboilers, such as internal reboilers, can also be used. The heat supplied to the reboiler can be derived from any heat generated in the process integrated with the reboiler, or from an external heat source such as other thermogenic chemical processes or boilers. Although the drawings only show the reactor and flash column, additional reactors, flash towers, condensers, heating elements, and other components can be used in various embodiments of the invention. It will be apparent to those skilled in the art that various condensers, pumps, compressors, reboilers, drums, valves, connectors, separation tanks, etc., which are typically employed for chemical processes, can also be used in the process of the present invention.

The temperature and pressure used in the distillation column can vary. In practice, although subatmospheric pressure and superatmospheric pressure can be used in some embodiments, in these areas Will use a pressure of 10 kPa to 3,000 kPa. The temperature in each zone is usually in the range between the composition which is removed as a distillate and the boiling point of the composition which is removed as a residue. It will be apparent to those skilled in the art that the temperature at a given location of the distillation column in operation depends on the material composition at that location and the pressure within the distillation column. In addition, depending on the scale of the manufacturing process, the feed rate can vary, and as described, can generally be expressed in terms of feed weight ratio.

The finished ethanol composition prepared by the embodiments of the present invention can be used in a variety of applications including fuels, solvents, chemical materials, pharmaceuticals, detergents, disinfectants, hydrogenated delivery or hydrogen consumer products. In fuel applications, the finished ethanol composition can be blended with gasoline for use in motor vehicles such as automobiles, boats and small piston engine aircraft. In non-fuel applications, the finished ethanol composition can be used as a solvent for cosmetic and cosmetic preparations, detergents, disinfectants, coatings, inks and pharmaceuticals. The finished ethanol composition can also be used in the process as a processing solvent for pharmaceutical products, food preparations, dyes, photochemical and latex processing.

The finished ethanol composition can also be used as a chemical raw material to make other chemicals such as vinegar, ethyl acrylate, ethyl acetate, ethylene, glycol ethers, ethylamines, aldehydes and higher alcohols, especially butanol. . On the production of ethyl acetate, the finished ethanol composition can be esterified with acetic acid. In another application, the finished ethanol composition can be dehydrated to produce ethylene. Any of the conventional dehydration catalysts can be used to dehydrate the ethanol, as described in U.S. Patent Application Publication No. 2010/0030002, the entire disclosure of which is incorporated herein by reference. For example, zeolite catalysts are available as dehydration catalysts. Preferably, the zeolite has a pore diameter of at least about 0.6 nm, and preferred zeolite comprises a dehydration catalyst selected from the group consisting of mordenite, ZSM-5, zeolite X and zeolite Y. For example, Zeolite X is described in U.S. Patent No. 2,882,244, the disclosure of which is incorporated herein by reference.

While the invention has been described in detail, various modifications of the embodiments of the invention may be apparent to those skilled in the art. In addition, it should be understood that the various aspects of the invention and aspects of the embodiments and the various features and/or the scope of the appended claims may be combined or interchanged in whole or in part. As will be apparent to those skilled in the art, in the foregoing, various implementations In the description of the formula, an embodiment with reference to another embodiment may be combined with one or several other embodiments as appropriate. In addition, it will be apparent to those skilled in the art that the foregoing description is intended to be illustrative and not restrictive.

100‧‧‧ system

101‧‧‧Reaction zone

102‧‧‧Separation zone

103‧‧‧Reactor/Hydrogen Reactor

104‧‧‧Line/hydrogen feed

105‧‧‧pipe

106‧‧‧Separator

107‧‧‧Distillation tower/first distillation tower

108‧‧‧pipeline/return line

109‧‧‧Second distillation tower/distillation tower

110‧‧‧Evaporator

111‧‧‧pipe

112‧‧‧ pipeline

113‧‧‧Vapor flow

114‧‧‧Liquid flow/pipeline

115‧‧‧pipe/distillation tower

116‧‧‧pipe

117‧‧‧pipe/first distillate

118‧‧‧Water separator

119‧‧‧ water flow

120‧‧‧Ethanol mixture flow

121‧‧‧pipe

122‧‧‧pipe

123‧‧‧pipe/second distillate

124‧‧‧hydrolysis unit

125‧‧‧Side flow/side extraction flow/pipeline

130‧‧‧Compressor

131‧‧‧film

132‧‧‧Infiltration Logistics

133‧‧‧pipe

134‧‧‧Retaining logistics

140‧‧‧Main pipeline

141‧‧‧Side pipe/flow

142‧‧‧Water flow

143‧‧‧Ethanol mixture flow/flow

144‧‧‧ Hydrolysis bypass line / hydrolysis side split / bypass line / flow

The invention is described more fully hereinafter with reference to the appended claims,

1 is a schematic diagram of an ethanol production system in accordance with an embodiment of the present invention having a hydrolysis unit and a water separator for removing water from the first distillate.

2 is a schematic diagram of an ethanol production system having a hydrolysis unit and a membrane for removing water from the first distillate, in accordance with an embodiment of the present invention.

Figure 3 is a schematic illustration of a water separator for removing water from a first distillate in accordance with an embodiment of the present invention.

100‧‧‧ system

101‧‧‧Reaction zone

102‧‧‧Separation zone

103‧‧‧Reactor/Hydrogen Reactor

104‧‧‧Line/hydrogen feed

105‧‧‧pipe

106‧‧‧Separator

107‧‧‧First Distillation Tower/Distillation Tower

108‧‧‧pipeline/return line

109‧‧‧Second distillation tower/distillation tower

110‧‧‧Evaporator

111‧‧‧pipe

112‧‧‧ pipeline

113‧‧‧Vapor flow

114‧‧‧Liquid flow/pipeline

115‧‧‧pipe/distillation tower

116‧‧‧pipe

117‧‧‧pipe/first distillate

118‧‧‧Water separator

119‧‧‧ water flow

120‧‧‧Ethanol mixture flow

121‧‧‧pipe

122‧‧‧pipe

123‧‧‧pipe/second distillate

124‧‧‧hydrolysis unit

125‧‧‧Side flow/side extraction flow/pipeline

Claims (40)

A process for producing ethanol, the process comprising the steps of: (a) hydrogenating acetic acid in the presence of a catalyst in a reactor to form a crude ethanol product; (b) in the first distillation column, the crude ethanol product Separating at least a portion to produce a first distillate comprising ethanol and ethyl acetate, and a first residue comprising acetic acid; and (c) in the second distillation column, at least the first distillate A portion is separated to produce a second distillate comprising ethyl acetate, and a side stream comprising ethanol. The process of claim 1, further comprising the step of hydrolyzing a portion of the ethyl acetate in the first distillate to form ethanol and acetic acid. The process of claim 2, wherein the step (c) further comprises forming a second residue comprising acetic acid. The process of claim 3, wherein the ratio of the ethanol separated in the side stream to the ethanol separated in the second residue is from 100:1 to 1:10. The process of claim 3, further comprising the step of recycling at least a portion of the acetic acid from the second residue to the reactor. The process of claim 3, further comprising the step of recycling at least a portion of the acetic acid from the second residue to the first distillation column. The process of claim 2, wherein the first distillate comprises at least 0.1% by weight water. The process of claim 7, wherein the first distillate initially has a water to molar ratio of ethyl acetate to more than 3:1. The process of claim 2, further comprising introducing a stream of water into the first distillate. The process of claim 2, wherein the hydrolysis occurs in an ion exchange bed. The process of claim 10, wherein the ion exchange bed is outside the first distillation column and is located between the first distillation column and the second distillation column. The process of claim 1, wherein the ethyl acetate in the first distillation column is hydrolyzed in an ion exchange bed in the first distillation column to form ethanol and acetic acid. The process of claim 1, wherein the first distillate initially comprises at least 0.5% by weight ethyl acetate. The process of claim 1, wherein the first distillate initially comprises at least 1% by weight ethyl acetate. The process of claim 1, wherein the first distillate initially comprises less than 2% by weight acetic acid. The process of claim 1, wherein at least 95% of the acetic acid fed to the first distillation column is separated into the first residue. The process of claim 1, wherein 30 to 90% of the water fed to the first distillation column is separated into the first residue. The process of claim 1, further comprising the step of recycling at least a portion of the ethyl acetate from the second distillate to the reactor. The process of claim 1, further comprising the step of recycling at least a portion of the ethyl acetate from the second distillate to the first distillation column. The process of claim 1, further comprising the step of removing water from at least a portion of the first distillate. The process of claim 20, wherein the first distillate comprises less than 10% by weight water after the water removal step. The process of claim 20, wherein the water is removed from the first distillate using an adsorption unit, a membrane, an extractive distillation column, a molecular sieve, or a combination thereof. The process of claim 20, wherein the water is removed from the first distillate using a pressure swing adsorption unit or a thermal adsorption unit. The process of claim 23, further comprising the step of hydrolyzing at least a portion of the ethyl acetate in the first distillate prior to the water removal step to form ethanol and acetic acid. The process of claim 20, wherein a portion of the removed water is added to the second distillation column. The process of claim 20, further comprising the step of adding water to the first step under conditions effective to hydrolyze ethyl acetate contained in the second distillation column to form additional ethanol and acetic acid. Distillation tower. The process of claim 1, wherein the side stream comprises from 10% to 99.5% by weight of ethanol, less than 1.0% by weight of ethyl acetate, and less than 1.0% by weight of acetic acid. The process of claim 1, wherein at least 10% of the ethanol fed to the second distillation column is recovered in the side stream. The process of claim 1, wherein the first distillation column is operated at a pressure of 0.1 to 510 kPaa. The process of claim 1, wherein the acetic acid conversion in the reactor is at least 90%. The process of claim 1, wherein the first distillate is fed to the second distillation column below the side stream. A process for producing ethanol, the process comprising the steps of: (a) hydrogenating acetic acid in the presence of a catalyst in a reactor to form a crude ethanol product; (b) in the first distillation column, the crude ethanol product At least a portion of the separation is performed to produce a first distillate comprising ethanol and ethyl acetate, and a first residue comprising acetic acid; (c) at least a portion of the ethyl acetate is effective to form additional ethanol and additional acetic acid Hydrolyzing under conditions; and (d) separating at least a portion of the first distillate in a second distillation column to produce a side stream comprising ethanol, and a second residue comprising residual acetic acid. A process for producing ethanol, the process comprising the steps of: (a) hydrogenating acetic acid in the presence of a catalyst in a reactor to form a crude ethanol product; (b) in the first distillation column, the crude ethanol product At least a portion of the separation is performed to produce a first distillate comprising ethanol, ethyl acetate and a small amount of acetic acid, and a first residue comprising acetic acid; (c) increasing the ethanol content and the acetic acid content of the first distillate And (d) separating at least a portion of the first distillate in the second distillation column to produce a second distillate comprising ethyl acetate, and a side stream comprising ethanol. The process of claim 33, wherein the step (d) further comprises forming a second residue comprising acetic acid. The process of claim 33, wherein water is added to the first distillate under conditions effective to hydrolyze ethyl acetate contained in the first distillate to form ethanol and acetic acid. For example, the process described in claim 33, wherein the acetic acid content is increased by at least 0.1%. For example, the process described in claim 33, wherein the ethanol content is increased by at least 0.1%. A process for purifying a crude ethanol product comprising ethanol, ethyl acetate and acetic acid, the process comprising the steps of: (a) separating at least a portion of the crude ethanol product in a first distillation column to produce ethanol And a first distillate of ethyl acetate, and a first residue comprising acetic acid; and (b) separating at least a portion of the first distillate in the second distillation column to produce ethyl acetate A second distillate, a side stream comprising ethanol, and optionally a second residue comprising acetic acid. The process of claim 38, further comprising hydrolyzing at least a portion of the ethyl acetate in the first distillate to form a hydrolyzed portion comprising ethanol and acetic acid prior to the separating in step (b). Distillate. The process of claim 39, wherein the separating step forms a second residue comprising acetic acid.