TW201332950A - Integrated ethanol production by extracting halides from acetic acid - Google Patents

Abstract

This invention relates to a process for producing ethanol and recovering methyl iodide, the process comprising the steps of carbonylating methanol in a carbonylation system in the presence of a carbonylation catalyst under conditions effective to form acetic acid; hydrogenating the acetic acid in a hydrogenation system in the presence of a hydrogenation catalyst to form a crude ethanol product comprising ethanol and water; and separating the crude ethanol product to form an ethanol stream and a water stream.

Description

Ethanol integration process for extracting halides by acetic acid

The present invention is broadly directed to an integrated process for producing ethanol from methanol via an acetic acid intermediate. In particular, the present invention relates to an integrated ethanol process in which a halide such as methyl iodide is removed from an acetic acid intermediate and the acetic acid intermediate is hydrogenated to form ethanol.

Industrially used ethanol is produced in a conventional manner from petrochemical feedstocks 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. Starch raw materials as well as cellulosic raw materials are often converted to ethanol via fermentation. However, fermentation is usually used for consumer production of ethanol. 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 reactions of alkanoic acids and/or other carbonyl containing compounds has been extensively studied, and various combinations of catalysts, supports and operating conditions are mentioned in the literature. In the reduction reaction of an alkanoic acid such as acetic acid, water is formed in a molar ratio to ethanol or the like.

Several processes for the production of ethanol from acetic acid and acetates including methyl acetate and ethyl acetate have been described in the literature.

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 consisting of acetic acid and ethyl acetate, and the stream of acetic acid and ethyl acetate is recycled to the hydrogenation reactor.

International patent WO2009063174 describes a continuous process for producing ethanol from a carbonaceous feedstock. first The carbonaceous feedstock is first converted to syngas, which is then converted to acetic acid, which is then esterified and hydrogenated to form ethanol.

WO2009009320 describes an indirect route to the production of ethanol. The sugar is fermented to form acetic acid under homoacidogenic conditions. Acetic acid is esterified with a primary alcohol having at least 4 carbon atoms and the ester is hydrogenated to form ethanol.

U.S. Patent Publication No. 20110046421 describes a process for producing ethanol comprising converting a carbonaceous feedstock to a syngas and converting the syngas to methanol. The methanol is carbonylated to acetic acid and the acetic acid is subjected to a two-stage hydrogenation process. The acetic acid is first converted to ethyl acetate, and a second hydrogenation reaction is carried out to produce ethanol.

U.S. Patent No. 7,884,253 describes a process for producing ethanol by converting syngas to methanol and catalytically converting methanol to acetic acid. Acetic acid and methanol are esterified to produce acetate. The acetate is reduced by hydrogen to produce ethanol.

A widely used and successful commercial acetic acid synthesis process involves the catalytic carbonylation of methanol using carbon monoxide. This catalytic reaction contains hydrazine and/or hydrazine, as well as a halogen promoter, usually methyl iodide. This reaction is carried out by continuously bubbling carbon monoxide through a liquid reaction medium in which the catalyst is dissolved. The reaction medium also contains methyl acetate, water, acetic acid, methyl iodide and the catalyst. Conventional commercial methanol carbonylation processes include those described in U.S. Patent Nos. 3,769,329, 5, 001, 259, 5, 026, 908, and 5, 144, 068, the entire disclosures of each of which are incorporated herein by reference. Another conventional methanol carbonylation process comprises Cativa ^TM process, which is discussed in Jones, JH (2002), The Cativa TM Process for the Manufacture of Acetic Acid, Platinum Metals Review, 44 (3): 94-105 This member Document , the entire contents and disclosures are incorporated herein by reference.

The crude acetic acid product from the reactor is treated in a purification zone to remove impurities and recover acetic acid. These impurities may affect the quality of the acetic acid in a trace amount, especially when the impurities circulate through the reaction process, especially causing these impurities to accumulate over time. Conventional purification techniques for removing these impurities include treating the acetic acid product stream with an oxidant, ozone, water, methanol, activated carbon, amines, and the like. These treatments can also be combined with a distillation procedure for the crude acetic acid product. However, additional processing of the final product increases the cost of the process, and distillation of the treated acetic acid product may result in the formation of other impurities.

The process used to remove these impurities may also remove compounds within the reaction medium, such as halogen promoters. Several processes have been taught for recycling halogen promoters, including vented streams Treatment method and extraction method.

The effluent treatment can recover the halogen promoter. For example, US Patent Publication No. 2009/0270651 discloses a methanol carbonylation system comprising an absorption tower adapted to receive an exhaust gas stream and to remove methyl iodide from the exhaust gas stream using a scrubber solvent. It is connected to a source of first and second purification solvents capable of supplying different first and second purification solvents. A switching system including a valve member alternately supplies the first or second purification solvent to the absorption column and returns the used solvent and absorbed material to the carbonylation system to accommodate different modes of operation.

The extraction process can also recover a halogen promoter from the carbonylation product. For example, U.S. Patent No. 4,908,477 discloses the separation of organic iodides from a carbonylation product of methanol, methyl acetate and methyl ether and a mixture of these products by a process in which non-aromatic hydrocarbons are used. (non-aromatic hydrocarbon) liquid extraction to remove iodide.

Although the foregoing process has successfully reduced and/or removed impurities in the oxonation system, it can be further modified to remove and recover the halogen promoter so that the feed stream substantially free of halogen promoter can be fed Into the hydrogenation reactor.

In a first embodiment, the invention is directed to a method for producing ethanol comprising the steps of reacting carbon monoxide with at least one reactant in a first reactor comprising a reaction medium to produce a product comprising acetic acid. a reaction solution, wherein the at least one reactant is selected from the group consisting of methanol, methyl acetate, methyl formate, dimethyl ether, and mixtures thereof, and wherein the reaction medium comprises water, acetic acid, and iodine. Methane and a first catalyst; extracting at least a portion of the reaction solution or a derivative thereof with at least one hydrophobic extractant to obtain an acetic acid intermediate product substantially free of methyl iodide; in the second catalyst The acetic acid intermediate is introduced into the second reactor in the presence of a crude ethanol product; and the ethanol is recovered from the crude ethanol product. Derivatives of the reaction solution may be obtained from a light ends distillation column and/or a permanganate reducing compound removal system.

In another embodiment, the invention is directed to a process for producing ethanol, the process comprising the steps of reacting carbon monoxide with at least one reactant in a first reactor comprising a reaction medium to produce acetic acid comprising a reaction solution, wherein the at least one reactant is selected from the group consisting of methanol, methyl acetate, methyl formate, methyl ether, and mixtures thereof, and wherein the reaction medium comprises water, acetic acid, methyl iodide, and a catalyst; the reaction solution is flashed to obtain a vapor stream; At least one hydrophobic extractant to extract a condensed portion of the vapor stream to obtain an acetic acid intermediate substantially free of methyl iodide; and in the presence of a second catalyst, the acetic acid intermediate is introduced into the second reactor to form ethanol a crude product; and recovering ethanol from the crude ethanol product.

In still another embodiment, the present invention is directed to a process for producing ethanol, the process comprising the steps of reacting carbon monoxide with at least one reactant in a first reactor comprising a reaction medium to produce an inclusion a reaction solution of acetic acid, wherein the at least one reactant is selected from the group consisting of methanol, methyl acetate, methyl formate, methyl ether, and mixtures thereof, and wherein the reaction medium comprises water, acetic acid, methyl iodide, and a first catalyst; the reaction solution is flashed to obtain a vapor stream; the vapor stream is separated in a light fraction distillation column to form an acetic acid side stream and comprising one or more permanganate reducing compounds, acetic acid An overhead stream of methyl ester, methanol, water, and methyl iodide, wherein the permanganate reducing compounds are selected from the group consisting of acetaldehyde, acetone, methyl ethyl ketone, butyraldehyde, crotonaldehyde, 2-ethyl crotonaldehyde, 2-B a group consisting of butyraldehyde, their aldol condensation products, and mixtures thereof; extracting a portion of the acetic acid side stream with at least one hydrophobic extractant Acetic acid to obtain an intermediate product containing substantially no methyl iodide; in the presence of a second catalyst, the acetic acid intermediate product is introduced into the second reactor to form a crude ethanol product; ethanol and recovering ethanol from the crude product.

10‧‧‧Integrated Process / Process

12‧‧‧carbonylation system

14‧‧‧halide extraction process

16‧‧‧Hydrogenation system

18‧‧‧Reactants

20‧‧‧ Carbon monoxide feed

22‧‧‧ acetic acid flow

24‧‧‧Acetic acid intermediate

26‧‧‧Extractant

28‧‧‧Iodine methane flow

30‧‧‧ hydrogen feed

32‧‧‧ethanol product stream

34‧‧‧Water flow

100‧‧‧Carbonation and acetic acid recovery system / carbonylation section / carbonylation process

101‧‧‧liquid carbonylation reactor/reactor

102‧‧‧pipe

104‧‧‧ Carbon monoxide feed

105‧‧‧Reagent feed

106‧‧‧pipe

111‧‧‧Flash Tower

112‧‧‧Low Volatile Catalyst Phase

113‧‧‧ overhead flow/flow

121‧‧‧Light Distillation Distillation Tower/Distillation Tower

122‧‧‧High boiling residue logistics

123‧‧‧ overhead distillation stream/low boiling overhead vapor stream/flow

124‧‧‧Side flow/acetic acid lateral flow

131‧‧‧Tower receiving decanter/decanter

132‧‧‧Condensing light phase/light phase/pipeline/acetic acid feed

133‧‧‧pipe

134‧‧‧Condensed heavy phase/heavy phase/pipeline

141‧‧‧ extractor

142‧‧‧ flow

143‧‧‧Extracted acetic acid intermediates/residue/acetic acid intermediates/pipes

145‧‧‧Extractant feed

150‧‧‧PRS unit

151‧‧‧Removing the distillation tower

154‧‧‧ pipeline

156‧‧‧ pipeline

157‧‧‧pipe

163‧‧‧Derived flow

164‧‧‧Extractant

170‧‧‧Distillation tower

171‧‧‧Second vapor phase/condensation flow tube

172‧‧‧High-boiling liquid phase steaming logistics

174‧‧‧lateral flow

175‧‧‧Tower Receiver

176‧‧‧pipe

177‧‧‧Pipe/Flow/Initial Logistics

180‧‧‧ extractor/container

183‧‧‧Waterborne acetaldehyde stream/acetaldehyde stream/result logistics

184‧‧‧Extractant/pipeline

190‧‧‧Second extractor

191‧‧‧ pipeline

192‧‧‧Removing the distillation tower

193‧‧‧Second raffinate logistics

194‧‧‧Residual logistics

195‧‧‧Extracted logistics/extract stream

196‧‧‧ Distillate Logistics

197‧‧‧pipe

198‧‧‧alkyl blowing purge

200‧‧‧Hydrogenation System/Hydrogenation Section/Hydrogenation Process

201‧‧‧Evaporator

202‧‧‧Drainage flow

203‧‧‧pipe

204‧‧‧Hydrogen feed/pipeline

205‧‧‧Accumulation flow/pipeline

210‧‧‧Reaction zone

211‧‧‧Reactor

212‧‧‧pipe

221‧‧‧Separator

222‧‧‧Liquid flow / liquid line / crude ethanol mixture

223‧‧‧Vapor flow

230‧‧‧Separation zone

231‧‧‧Distillation Tower/First Distillation Tower/Acid Separation Distillation Tower

232‧‧‧pipe

233‧‧‧pipe

241‧‧‧Distillation Tower/Second Distillation Tower/Light Distillation Distillation Tower

242‧‧‧pipe

243‧‧‧ pipeline

244‧‧‧pipe

251‧‧‧Distillation tower/third distillation tower/product distillation tower

252‧‧‧pipe

253‧‧‧pipe

261‧‧‧The fourth distillation column/acetaldehyde removal distillation column

262‧‧‧ pipeline

263‧‧‧ pipeline

271‧‧‧First Distillation Tower/Distillation Tower

272‧‧‧First residue/pipeline

273‧‧‧First distillate/pipeline

274‧‧‧pipe

275‧‧‧pipe

281‧‧‧Water separation unit

282‧‧‧Water flow

283‧‧‧Ethanol mixture flow

284‧‧‧pipe

285‧‧‧pipe

291‧‧‧Second Distillation Tower/Light Distillation Distillation Tower

292‧‧‧ pipeline

293‧‧‧pipe

301‧‧‧First Distillation Tower/Distillation Tower

302‧‧‧pipe

303‧‧‧ pipeline

311‧‧‧Second Distillation Tower/Acid Separation Distillation Tower

312‧‧‧pipe/second residue

313‧‧‧pipe/second distillate

The invention is described in detail below with reference to the drawings, wherein like numerals refer to like elements.

1 is a schematic diagram showing an integrated system for producing ethanol from methanol via an acetic acid intermediate product, in accordance with an embodiment of the present invention.

Fig. 2 is a schematic view showing an integrated ethanol production system according to an embodiment of the present invention, in which a halide is extracted from a side stream of acetic acid.

Figure 3 is a schematic diagram showing an integrated ethanol production system in accordance with an embodiment of the present invention in which a halide is extracted by a permanganate reducing compound removal system.

Figure 4 is a schematic diagram showing an integrated ethanol production system in accordance with an embodiment of the present invention in which a halide is extracted from a vapor stream of a flash column.

Fig. 5 is a schematic view showing an ethanol production system according to an embodiment of the present invention, which has a water removal process.

Fig. 6 is a schematic view showing an ethanol production system according to an embodiment of the present invention, which has two distillation columns.

preface

The present invention broadly relates to an integrated process for producing ethanol from methanol. In one embodiment, the process comprises subjecting methanol to carbonylation under conditions effective to form acetic acid in a carbonylation system in the presence of a oxonation catalyst. The carbonylation catalyst may comprise a Group VIII metal and a promoter such as a halide. When commercializing acetic acid, the accelerator may comprise methyl iodide. In order to maintain the efficiency of acetic acid production, methyl iodide is removed and returned to the carbonylation reactor. However, when integrating acetic acid production and ethanol production, it is possible to use an acetic acid intermediate stream having a higher water content than, for example, higher than 0.15 wt% water, compared to high grade acetic acid, or more than high grade acetic acid. An acetic acid intermediate product stream of other impurities such as aldehydes. This reduces the energy required to separate the acetic acid.

However, reducing the separation procedure may result in the presence of methyl iodide in the acetic acid intermediate and thus be fed to the hydrogenation reactor. Without being bound by theory, it is believed that halides may cause the catalyst to become inactive. The presence of a halide may be detrimental to the hydrogenation catalyst, resulting in loss of catalytic function. In addition, even if the halide is not harmful to a particular type of catalyst, removal of the halide is beneficial to reduce the concentration of these impurities in the final recovered ethanol end product. Furthermore, it is advantageous to retain methyl iodide in the oxo system without introducing another compound into the hydrogenation system.

The acetic acid intermediate containing the reduced amount of methyl iodide is then hydrogenated in the hydrogenation system in the presence of a hydrogenation catalyst to form a crude ethanol product comprising ethanol and water.

FIG. 1 shows an exemplary integrated process 10 in accordance with an embodiment of the present invention. Process 10 includes a carbonylation system 12, a halide extraction process 14 and a hydrogenation system 16. The oxonation system 12 accepts a reactant 18, such as methanol or a derivative thereof, and a carbon monoxide feed 20. Methanol and carbon monoxide are reacted in a carbonylation system 12 to form a acetic acid stream 22. The acetic acid stream 22 can comprise up to 25% by weight water, for example up to 20% by weight water or up to 10% by weight water. In terms of ranges, the acetic acid stream 22 can comprise from 0.15 wt% to 25 wt% water, such as from 0.2 wt% to 20 wt%, from 0.5 to 15 wt%, or from 4 wt% to 10 wt% water. The acetic acid stream 22 is passed through a halide extraction process 14 to reduce the concentration of halide in a raffinate such as acetic acid intermediate 24. The halide concentration in the acetic acid intermediate 24 can vary, but is generally less than 10 wppm (ppm by weight), such as 5 wppb (wt ppb) to 500 wppb, such as 10 wppb to 200 wppb or 10 wppb to 100 wppb. .

In some embodiments, a derivatized stream from the oxonation system 12, such as an aldehyde-enriched stream, can be passed through a halide extraction process 14 to remove halide impurities. Halogenation The material extraction process 14 is a liquid-liquid extraction process.

In one embodiment, the halide impurities is the use of acetic acid and extraction agent 26 is removed from the intermediate product 24, the extraction agent 26 may be selected from the group consisting of a combination of C ₅ to C ₁₆ alkanes and their freedom of. Preferably, the extractant is hydrophobic and does not extract acetic acid and/or acetaldehyde. In some embodiments, the extraction agent is a C ₆ C ₁₆ alkanes, and more preferably to a C ₈ to C ₁₂ alkanes. In some embodiments, the extractant is decane, dodecane, or a combination thereof. The methyl iodide stream 28 can be recovered and returned to the carbonylation system 12. In one embodiment, at least 70% of the halide impurities from the acetic acid stream 22 are removed from the halide extraction process 14, such as preferably removing at least 85% or at least 95% of the halide impurities.

The acetic acid intermediate 24 is fed to the hydrogenation system 16, more preferably directly to the hydrogenation system 16. Hydrogenation system 16 also receives hydrogen feed 30. In the hydrogenation system 16, acetic acid and organics are hydrogenated to form a crude ethanol product comprising ethanol, as well as other compounds such as water, ethyl acetate and acetic acid. The hydrogenation system 16 further comprises one or more separation units, such as a distillation column and/or an extraction unit (not shown in Figure 1), to recover ethanol from the crude ethanol product. The ethanol product stream 32 is then recovered by the hydrogenation system 16. Water stream 34 can also be obtained from hydrogenation system 16 and purged if necessary. A portion of the water stream 34 can be used as an extractant in the carbonylation system 12 and/or the hydrogenation system 16. In one embodiment, the ethanol product stream 32 and the water stream 34 are substantially free of methyl iodide.

In addition to integrating the water flow between the hydrogenation system 16 and the oxonation system 12, the process can be integrated with the process for producing acetic acid and/or the process for producing methanol. For example, acetic acid can be produced from methanol, and thus ethanol production achieved in accordance with embodiments of the present invention can be produced from methanol. In one embodiment, the invention comprises producing methanol from syngas, carbonylating methanol to form acetic acid, and reducing acetic acid to an alcohol, i.e., ethanol. In another embodiment, the invention comprises forming acetic acid and acetic acid by converting a carbon source such as coal, biomass material, petroleum or natural gas into synthesis gas, and converting the synthesis gas into methanol, carbonylating methanol. It is reduced to form ethanol, thereby producing ethanol from the carbon source. In still another embodiment, the present invention comprises carbonylating methanol by converting a carbon source such as coal, biomass material, petroleum or natural gas into a synthesis gas, separating the synthesis gas into a hydrogen stream and a carbon monoxide stream, and using a carbon monoxide stream. Acetic acid is formed and acetic acid is reduced to form ethanol, thereby producing ethanol from the carbon source. In addition, methanol can be produced from syngas.

In some embodiments, in addition to the extraction, a guard bed can be utilized to remove the halides and/or sulfides, as described in U.S. Patent Application Serial No. 13/078,751, filed on Apr. 1, 2011. The entire contents and disclosure of the application are hereby incorporated by reference. The guard bed can include any type of abuse Ion exchange resin. The resins used in the present invention may include functional groups exchanged by metals as described in U.S. Patent Nos. 5,220,558 and 4,615,806, the entireties of each of which are incorporated herein by reference. For example, an ion exchange resin or an ion exchange resin can be replaced by contacting the resin with silver, palladium or a mercury salt to remove from about 1 to about 99 percent of the resin active sites into silver, palladium or mercury. Other suitable substrates are prepared for use in the present inventors. Silver-containing forms, such as functionalized by silver, are particularly suitable for removing halogen contaminants. In some embodiments, the ion exchange resin is functionalized to form a coprecipitate with impurities contained in the stream. The metal loading on the resin can vary widely, and preferably occupies at least 1% of the active site, and more preferably from 10 to 90% by weight of the active site, such as from 30 to 70% of the active site. See, for example, U.S. Patent No. 6,225,498, the entire disclosure of which is incorporated herein by reference in its entirety, the entire entire entire entire entire entire entire entire disclosure The medium is in contact with a cation exchange resin substrate that has been replaced by silver or mercury. See also U.S. Patent Nos. 5, 801, 279, 5, 416, 237, 5, 227, 524, and 5, 139, 981, and European Patent No. 0 685 445, the entire contents of each of which are incorporated herein by reference.

Various carbonylation systems and hydrogenation systems can be used in the process of the present invention. Exemplary materials, catalysts, reaction conditions, and separation processes useful in the carbonylation systems and hydrogenation systems employed in the present invention are further described below.

Carbonylation system

In the carbonylation process, methanol and carbon monoxide are reacted in the presence of a carbonylation reactor under conditions effective to form acetic acid. In some embodiments, some or all of the feedstock for the carbonylation 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 mixture of ethanol can be separated from the syngas, as will be described in further detail below. 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.

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 Flakes, 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, American mountain Walnut shell, coconut shell, coffee grounds, compressed hay, hay, 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 hydrogasification of solid and/or liquid carbonaceous materials to obtain process gas, which is further vapor pyrolyzed with natural gas to form a synthesis gas. The syngas is converted to methanol and the methanol is carbonylated to acetic acid. This process also produces hydrogen, which can be used in the hydrogenation system 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.

Methanol or another carbonylation reaction comprising, but not limited to, methyl acetate, methyl formate, methyl ether or a mixture thereof, is converted to a carbonylation reaction of acetic acid, preferably in Group VIII such as hydrazine Occurs in the presence of a metal catalyst and a halogen-containing catalyst promoter. A particularly useful process is the low water hydrazine-catalyzed carbonylation process for the carbonylation of methanol to acetic acid as exemplified in U.S. Patent No. 5,001,259, the disclosure of which is incorporated herein by reference.

Without being bound by theory, it is believed that the ruthenium component in the catalyst system exists in the form of a ruthenium complex, and at least one of the ligands is a halogen component. In addition to the coordination relationship between hydrazine and halogen, it is believed that carbon monoxide also coordinates to hydrazine. The compound which can form a coordination compound by using a ruthenium salt such as a ruthenium metal such as an oxide, an acetate, an iodide salt, a carbonate, a hydroxide or a chloride salt or in a reaction environment. The form is introduced into the reaction zone to provide the enthalpy component of the catalyst system.

The halogen-containing catalyst promoter of the catalyst system comprises a halogen compound, usually an organic halide. Thus, alkyl, aryl and substituted alkyl or aryl halides can be used. Preferably, the halogen-containing catalyst promoter is in the form of an alkyl halide. More preferably, the halogen-containing catalyst promoter is in the form of an alkyl halide, The alkyl group corresponds to the alkyl group of the alcohol feed to be carbonylated. Thus, in the carbonylation reaction which carbonylates methanol to acetic acid, the halide promoter will comprise a methyl halide, and more preferably comprises methyl iodide.

However, methyl iodide may cause corrosion and may poison the reducing catalyst in the hydrogenation reactor. Embodiments of the present invention advantageously increase the amount of methyl iodide recovered from the alkyl purge purge stream in the carbonylation process. In a preferred embodiment, substantially no methyl iodide is fed to the hydrogenation reactor and the methyl iodide is recovered by the carbonylation system, thereby reducing cost and increasing the efficiency of the integration process.

The liquid reaction medium used may include any solvent compatible with the catalyst system, and may include a pure alcohol or a mixture of the alcohol starting material and/or the desired carboxylic acid and/or the two compounds. The esters formed. Preferred solvents and liquid reaction vehicles for the low water carbonylation process contain the desired carboxylic acid product. Therefore, in the carbonylation reaction of methanol carbonylation to acetic acid, a preferred solvent system contains acetic acid.

The reaction medium contains water, but it is desirable that the water concentration be much lower than the practical water concentration that has heretofore been determined to achieve a sufficient reaction rate. It has been taught in the prior art that in the rhodium-catalyzed carbonylation reaction of the type described herein, the addition of water exerts a beneficial effect on the reaction rate. See, for example, U.S. Patent No. 3,769,329, the disclosure of which is incorporated herein by reference. Therefore, commercial operation is typically carried out at a water concentration of at least about 14% by weight. Accordingly, it is not expected that a water concentration of less than 14% by weight and as low as about 0.1% by weight can be expected to achieve a substantially equal or higher reaction rate compared to the reaction rate obtained at such a higher level of water concentration. .

According to the carbonylation process of the present invention which is most suitable for the production of acetic acid, by retaining an ester composed of a desired carboxylic acid and an alcohol in the reaction medium, preferably from the desired carboxylic acid and carbonylation The esters formed by the alcohols used, as well as the additional iodide ions above and above the iodide ions in the form of hydrogen iodide, provide the desired reaction rate even at low water concentrations. An example of a preferred ester is methyl acetate. The additional iodide ion is preferably an iodide salt, preferably lithium iodide. It has been found that at low water concentrations, methyl acetate and lithium iodide act as rate promoters only in the presence of higher concentrations, respectively, and the promotion is higher when both compounds are present. See, for example, U.S. Patent No. 5,001,259, the disclosure of which is incorporated herein by reference. It is believed that the concentration of iodide ions retained in the reaction medium of the preferred carbonylation reaction system is relatively high compared to the trace amounts of the halide salts used in this type of reaction system. The absolute concentration of the iodide ion content does not limit the availability of the present invention.

It is suitable for forming carbonyl by contacting the methanol feed with gaseous carbon monoxide which is bubbled through an acetic acid solvent reaction medium containing a ruthenium catalyst, a methyl iodide promoter, methyl acetate and an additional soluble iodide salt. Under the conditions of temperature and pressure of the product, methanol is subjected to a carbonylation reaction to become an acetic acid product. It is generally believed that the concentration of iodide ions in the catalyst system is important, rather than the cations bound to the iodide ions, and at a given concentration of iodide ions, the nature of the cations is not as pronounced as the effect of the concentration of iodide ions. The reaction medium may hold any metal iodide salt, or any organic cation or any iodide salt such as a quaternary amine or a phosphine or an organic cation such as a cation, as long as the salt has sufficient solubility in the reaction medium. Provide the desired iodide level. When the iodide salt is a metal salt, it is preferably an iodide salt of a member of the group consisting of Group IA and Group IIA metals of the Periodic Table, such as "Handbook of Chemistry and Physics" published by CRC Press, Cleveland, Ohio, 2002-03 (83th edition). In particular, an alkali metal iodide salt can be used, and lithium iodide is particularly suitable. In the low water carbonylation process most suitable for use in the present invention, the additional iodide salt above and above the iodide ion in the form of hydrogen iodide is typically present in the catalyst solution at a level such that the total concentration of iodide ions is about From 2% by weight to about 20% by weight, and methyl acetate is usually present in an amount of from about 0.5 to about 30% by weight, and methyl iodide is usually present in an amount of from about 5 to about 20% by weight. The amount of rhenium catalyst present is typically from about 200 to about 2000 parts per million (ppm).

A typical reaction temperature for the oxonation reaction is from 150 to 250 ° C, and a temperature range of from 180 to 220 ° C is a preferred range. The partial pressure of carbon monoxide in the reactor can vary widely, but is typically from about 2 to about 30 atmospheres, and preferably from about 3 to about 10 atmospheres. The total reactor pressure will range from about 15 to about 40 atmospheres due to the partial pressure of the by-products and the vapor pressure of the liquid contained.

In the carbonylation reaction of methanol, permanganate reducing compounds (PRC's) such as acetaldehyde and PRC precursors may be formed as by-products, which results in a carbonylation system preferably including a PRC removal system (PRS). For the removal of these PRC's. The PRC's may include compounds such as acetaldehyde, acetone, methyl ethyl ketone, butyraldehyde, crotonaldehyde, 2-ethyl crotonaldehyde, 2-ethyl butyraldehyde, and the like, and their aldol condensation products. Accordingly, in some embodiments, the present invention is directed to methods for reducing and/or removing PRC's or their precursors in an intermediate product stream during the formation of acetic acid in the carbonylation process.

In some embodiments, the present invention is directed to a process wherein a condensed liquid phase from the top of a light ends distillation column is subjected to a distillation step to obtain an overhead stream, the top stream being subjected to a water extraction step to selectively reduce and / or remove the PRC's in the process. In one embodiment, the distillation step in the PRS comprises a single distillation column as described in U.S. Patent No. 7,855,306, the entire disclosure of which is incorporated herein by reference in The or more distillation steps are described, for example, in U.S. Patent No. 6,143,930, the disclosure of which is incorporated herein by reference. Similarly, in an embodiment Wherein the extraction step in the PRS comprises a single extraction unit, while in other embodiments, several extraction units using the same or different extractants may be utilized, as described in, for example, U.S. Patent No. 7,223,886, the entire contents of which are incorporated herein. reference. Although the PRS exemplified and described in this specification has a single distillation column and a single extraction unit, it should be understood that the principles of the present invention can also be applied to a separation system having several distillation columns and/or several extraction units.

A typical reaction and acetic acid recovery system 100 for performing iodine-promoted ruthenium catalyzed carbonylation to carbonylate methanol to acetic acid is shown in Figure 2 and includes a liquid phase carbonylation reactor 101, a flash column 111, and a light Fraction distillation column 121. A carbon monoxide feed 104 and a reactant feed 105 comprising methanol, methyl acetate, methyl formate, methyl ether or a mixture thereof are fed to reactor 101. The carbonylation product is continuously withdrawn in line 102 and supplied to flash column 111, while a volatile ("vapor") overhead stream 113 comprising acetic acid and a low containing catalyst-containing solution are obtained in flash column 111. Volatile catalyst phase 112. The reactor 101 can be vented and a portion of the carbon monoxide can be directed to the flash column 111 via line 106 to stabilize the catalyst therein. A volatile overhead stream 113 comprising acetic acid is supplied to the light ends distillation column 121, wherein the distillation process produces an acetic acid product removed via the side stream 124, and an overhead stream 123 (hereinafter referred to as "low boiling overhead vapor" flow").

The carbonylation reactor is typically a stirred tank or bubble column reactor, and the reactive liquid or slurry contents are automatically maintained at a constant level within the reactor. Fresh methanol, carbon monoxide, and sufficient water to maintain at least a limited water concentration in the reaction medium are continuously introduced into the reactor. A recycle catalyst solution, such as a recycle catalyst solution from the base of the flash column, and a recycled methyl iodide phase, a recycled methyl acetate phase, and a recycled aqueous acetic acid phase are also introduced into the reactor. The recycle phase can contain one or more of the foregoing ingredients.

A distillation system is employed to provide means for recovering crude acetic acid and recycling the catalyst solution, methyl iodide, methyl acetate, and other system components in the process. In a typical carbonylation process, carbon monoxide is continuously introduced into the carbonylation reactor, preferably below the agitator for agitating the contents. The gaseous feed is completely dispersed in the reaction liquid by the stirring device. The gaseous purge purge stream is preferably discharged from the reactor to prevent accumulation of gaseous by-products and maintain a set partial pressure of carbon monoxide at a given total reactor pressure. The temperature of the reactor is controlled and the carbon monoxide feed is introduced at a rate sufficient to maintain the desired total reactor pressure.

The liquid product is withdrawn from the carbonylation reactor at a rate sufficient to maintain a constant level in the carbonylation reactor and introduced into the flash column. In the flash column, the catalyst-containing solution (catalyst phase) is extracted It is a base stream (mainly acetic acid containing hydrazine and iodide salts, and a smaller amount of methyl acetate, methyl iodide and water), and the vapor top stream containing acetic acid is withdrawn from the top of the column. The vapor top stream containing acetic acid also contains methyl iodide, methyl acetate and water. The dissolved gas leaving the reactor and entering the flash column contains a portion of carbon monoxide and may also contain gaseous by-products such as methane, hydrogen, and carbon dioxide. These dissolved gases leave the flash column and become part of the overhead stream. As explained above, the overhead stream is introduced into the light fraction distillation column 121 in the form of stream 113.

It has been disclosed in U.S. Patent Nos. 6,143,930 and 6,339,171 that the concentration of PRC's in the low-boiling overhead vapor stream 123 discharged from the distillation column 121, particularly the acetaldehyde content, is generally higher than that discharged from the distillation column 121. The one of the boiling residue stream 122 is higher. The low boiling overhead vapor stream 123 typically contains methyl iodide, acetaldehyde, methyl acetate, acetic acid, and water. The low boiling overhead vapor stream 123 is condensed and introduced into the overhead receiving decanter 131. The conditions in the process are preferably maintained such that the low boiling overhead vapor stream 123 is cooled sufficiently to condense and separate the condensable methyl iodide, acetaldehyde, methyl acetate, other carbonyl components and water into two phases. temperature. A portion of stream 123 may include non-condensable gases such as carbon dioxide, hydrogen, and the like, and these non-condensable gases may be discharged via line 133 as shown in FIG.

The condensed light phase 132 in the decanter 131 typically comprises water, acetic acid, acetaldehyde, methyl iodide, methanol, and methyl acetate. The condensed heavy phase 134 in the decanter 131 can be returned to the reactor 101, and a portion of the light phase can optionally be returned to the light ends distillation column 121 or returned to the reactor 101 after being combined with the line 134. Although any phase of the light ends overhead stream can be treated in a subsequent process, either phase of the low boiling overhead vapor stream 123 is treated to remove PRC's and primarily remove acetaldehyde, but Preferably, the PRC's are removed from the condensed lightweight phase 132.

Accordingly, the condensed heavy phase 134 in the decanter 131 can be suitably recycled directly or indirectly to the reactor 101, and optionally recycled with a portion of the light phase 132. For example, a portion of this condensed heavy phase 134 can be recycled to the reactor, and typically has a small amount of heavy phase 134, such as 25% by volume and preferably less than about 20% by volume heavy phase 134, It is introduced into the carbonyl processing process in the form of a slip stream. This substream of heavy phase 134 can be treated separately or combined with condensed light phase 132 to further distill and extract carbonyl impurities.

The acetic acid side stream 124 is withdrawn from the light ends distillation column 121 and directed to an extractor 141 to remove halides, particularly methyl iodide. One of the main considerations in the extraction step to separate methyl iodide is the relative solubility of methyl iodide in water. The acetic acid side stream 124 can comprise water in an amount up to 25% by weight, such as high At 0.15 wt% water. The increase in the solubility of methyl iodide in water is accompanied by the loss of methyl iodide from the process system, and the solubility of methyl iodide in water increases with the level of methyl acetate and/or methanol. At a sufficiently high level of methyl acetate and/or methanol, phase separation of methyl iodide may not occur during the extraction process. Accordingly, it is preferred that the acetic acid side stream 124 contains methanol and methyl acetate in a combined concentration of less than about 10% by weight, more preferably less than about 5% by weight, still more preferably less than about 2% by weight, and especially low. It is preferably about 1.5% by weight.

In the extractor 141, an extractant from the extractant feed 145 is used to extract methyl iodide. The extraction can be a single stage or multi-stage extraction, and any equipment used to carry out such an extraction process can be used to practice the invention. Especially multi-stage extraction is preferred. The extractant is preferably selected from the group consisting of C ₅ to C ₁₆ alkanes and combinations thereof. This extraction process causes the side stream 124 to be separated into a raffinate acetate intermediate 143, and a stream 142 comprising methyl iodide. As described herein, raffinate 143 is an acetic acid intermediate that can be fed to hydrogenation system 200 to produce ethanol.

Accordingly, it is preferred that the combination of temperature and pressure at which the extraction proceeds can maintain the extractor contents in a liquid state. Further, it is preferred to minimize the temperature at which the stream 124 is exposed so as to minimize the possibility of polymerization and condensation reactions associated with acetaldehyde. In some embodiments, the extraction is carried out at a temperature of from 10 °C to 40 °C.

While the particular composition of stream 142 can vary widely, it is preferred that most of the methyl iodide in line 124 be transferred to stream 142. In one embodiment, at least 70% of the methyl iodide is transferred to stream 142, and more preferably, for example, at least 85% or at least 95% of the methyl iodide is transferred to stream 142. In a preferred embodiment, about 99% or more of the methyl iodide is transferred to stream 142. In one embodiment, the acetic acid intermediate in the raffinate 143 does not substantially comprise methyl iodide.

Stream 142 is directed to removal distillation column 151 to produce a distillate stream and an extractant residue stream in line 156. The distillate stream in line 154 can be purged via line 157 and the remainder can be condensed. A portion may be refluxed as needed, and the residual portion may be returned to the carbonylation reactor 101.

In another embodiment, as shown in Figure 3, the derivatized stream can be passed through a halide extraction process and can be fed to a hydrogenation system. The derivative stream can be fed in combination with the acetic acid side stream 124 or separately. Preferably, the derivatized stream is an aldehyde-rich stream. As described above, the light phase 132 can contain PRC's, methyl iodide, methanol, and/or methyl acetate. To remove PRC's from the system, the light phase 132 can be fed to one or more distillation columns 170 (showing one distillation column 170), while the distillation column 170 is used to form acetaldehyde-rich However, it also contains the second vapor phase 171 of methyl iodide because the boiling points of methyl iodide and acetaldehyde are similar. The second vapor phase stream 171 at the top of the column is enriched with acetaldehyde relative to the light condensed liquid phase in line 132. The second vapor phase stream 171 lacks methyl acetate, methanol, and/or acetic acid relative to the light condensed liquid phase in line 132 (preferably all of which are lacking). The second vapor phase 171 is condensed and subsequently extracted with water to reduce and/or remove acetaldehyde. In a preferred embodiment, a portion of the condensate stream is supplied to line 176 to become a reflux to distillation column 170. This can be accomplished by supplying a condensed stream 171 to the overhead receiver 175, from which a portion of the condensed stream 171 can be supplied to the extractor 180 via line 177 or fed back to the distillation column 170 via line 176. .

In an alternative embodiment, the side stream 174 comprising methyl acetate is also extracted from distillation column 170. If side stream 174 is used, side stream 174 will enable distillation column 170 to operate under conditions suitable for obtaining a higher concentration of acetaldehyde in second vapor phase stream 171 while providing for removal in distillation column 170. Central or a mechanism for pushing methyl acetate in the second vapor phase stream 171 at the top of the column. Preferably, the side stream 174 is retained in the process by recycling the side stream 174 to the reactor 101, the light ends distillation column 121 or the decanter 131.

Further in accordance with an embodiment of the invention, water is used to extract the second vapor phase stream 171 to remove residual PRC's, particularly acetaldehyde. It was found that operation was carried out without the use of side stream 174, which would achieve the following results based on the separation capacity of distillation column 170, as shown in Table 1.

The extraction with water can be a single stage or multi-stage extraction, and any equipment used to carry out such an extraction process can be used to practice the invention. Especially multi-stage extraction is preferred. For example, extraction can be achieved by combining stream 177 with water. Multiple mixer/separator combinations can be applied in series to achieve multi-stage extraction. Optionally and preferably multi-stage extraction is achieved in a single vessel having a series of trays. The container may be provided with paddles or other agitation mechanisms to enhance extraction efficiency. in In such a multi-stage extraction vessel, preferably stream 177 is fed near one end of vessel 180, and extractant 184 is fed near the other end of vessel 180 or other location where countercurrent is achieved.

The relative solubility between the two phases during the extraction can increase with temperature. Accordingly, it is preferred that the extraction be carried out in a combination of temperature and pressure which maintains the contents of the extractor in a liquid state. Further, it is preferred to minimize the temperature at which the stream 177 is exposed so as to minimize the possibility of polymerization and condensation reactions associated with acetaldehyde. The water used in the extraction process is preferably from an internal stream to maintain the water balance in the carbonylation system. In some embodiments, water is derived from hydrogenation zone 200. Methyl ether (DME) can also be introduced during the extraction to enhance the separation of methyl iodide during the extraction process, that is, to reduce the loss of methyl iodide in the aqueous acetaldehyde stream 183. The DME can be imported into the process or can be generated in situ.

Acetaldehyde is extracted using an extractant in line 184 to obtain an aqueous acetaldehyde stream 183, which is also referred to as a derivative stream. The raffinate 182 primarily contains methyl iodide, which can be purged or recovered by the system for further processing and/or utilization. The efficiency of extraction depends on the number of extraction stages and the ratio of water to feed. The extractant in line 184 can comprise water, methyl ether and/or alkanes. When using a multi-stage extractor, each stage can have a different extractant. As explained above, when water is used as the extractant, it is preferred to use a part of the water in the reaction in the hydrogenation process.

The acetaldehyde stream 183 can be subjected to further processing as shown in Figure 3. The acetaldehyde stream 183 is directed to a second extractor 190 to further separate the methyl iodide from the acetaldehyde stream 183. The second extractant in line 191 is preferably different from the first extractant. A second extraction agent is preferably selected from the group consisting of compositions consisting of C ₅ to C ₁₆ alkanes and their associates. This extraction process causes the extracted acetaldehyde stream 183 to be separated into a second raffinate stream 193 comprising water and acetaldehyde, and an extract stream 195 comprising an extractant and methyl iodide. The second raffinate stream 193 is fed to the acetic acid stream 205 for use in the hydrogenation process 200. While the particular composition of the second raffinate stream 193 can vary widely, the second raffinate stream 193 preferably comprises less than 2% by weight methyl iodide, such as less than 1% by weight methyl iodide or less than 0.5% by weight. Or less than 0.1% by weight or substantially free of methyl iodide, such as less than 10 wppm of methyl iodide.

The extract stream 195 is directed to a removal distillation column 192 to produce a methyl iodide-containing distillate stream 196, a residual stream 194 comprising an extractant, which is fed to line 191 and returned to the second extractor 190, and an alkyl group (iodine). Blowing purge stream 198, which may be further processed or reused. The distillate stream 196 is condensed and can be returned to the reactor via line 197 or purged by system blowing. Distillate stream 196 comprises methyl iodide.

In an embodiment employing side stream 174, a second steaming at the top of the column relative to the light condensing liquid phase 132 Gas phase stream 171 is enriched with PRC, particularly acetaldehyde. Relative to the light condensate phase 132, the second vapor phase stream 171 at the top of the column lacks methyl acetate, methanol and/or acetic acid (preferably all of which are lacking). Relative to the side stream 174, and preferably also relative to the high boiling liquid phase vapor stream 172, the second vapor phase stream 171 at the top of the column lacks methyl acetate, methanol and/or acetic acid (preferably all These three are lacking). Preferably, the second vapor phase stream 171 at the top of the column is enriched with PRC's, particularly acetaldehyde, relative to the side stream 174 and the high boiling liquid phase vapor stream 172.

This process has been found to reduce and/or remove PRC's and their precursors, polyalkylalkyl iodide impurities, and propionic acid and higher carboxylic acids in the carbonylation process. It has been shown that a sufficient amount of acetaldehyde and derivatives thereof are reduced and/or removed such that the propionic acid concentration in the acetic acid product can be maintained below about 500 parts per million by weight (wppm), preferably Below about 300 wppm, and most preferably below 250 wppm.

In various embodiments of the invention, it is important to inhibit the formation of various aldehyde-related polymers and condensation products in distillation column 170. Acetaldehyde is polymerized to form metaldehyde and paraldehyde. These polymers are generally of low molecular weight and less than about 200. It is also possible to form a high molecular weight polymer of acetaldehyde. It is believed that these high molecular weight polymers (molecular weight greater than about 1000) will form during the processing of the light phase and are viscous and thixotropic. Acetaldehyde may also undergo an undesired aldol reaction.

The formation of such impurities as polyacetaldehyde and paraldehyde and high molecular weight acetaldehyde polymer can be suppressed by introducing a flushing stream containing at least water and/or acetic acid into the distillation column 170.

In another embodiment, as shown in FIG. 4, the overhead stream 113 from the flash column 111 is condensed and introduced into the extractor 141. Additionally, extractant feed 145 is fed to extractor 141. The extraction can be a single stage or multi-stage extraction, and any equipment used to carry out such an extraction process can be used to practice the invention. Especially multi-stage extraction is preferred. For example, extraction can be achieved by combining stream 177 with water. At extractor 141, an extractant from extractant feed 145 is utilized to extract methyl iodide. The extractant is preferably selected from the group consisting of C ₅ to C ₁₆ alkanes and combinations thereof. This extraction process causes the overhead stream 113 to be separated into a raffinate 143 comprising an acetic acid intermediate 143 and a stream 142 comprising methyl iodide, which can be fed to the hydrogenation system 200.

Similar to other embodiments, stream 142 is introduced into removal distillation column 151 to produce a distillate stream and an extractant residue stream in line 156. The distillate stream in line 154 can be purged via line 157 and the remainder can be condensed. A portion may be refluxed as needed, and the residual portion may be returned to the carbonylation reactor 101.

Hydrogenation system

As discussed earlier, the process for producing ethanol incorporates a carbonylation system and a hydrogenation system. The hydrogenation system preferably includes a hydrogenation reactor and a hydrogenation catalyst system effective for converting the acetic acid intermediate to ethanol and water. The hydrogenation system also includes a separation system for separating the crude ethanol product into an ethanol product stream, a water stream, and optionally one or more byproduct streams.

In addition to acetic acid, the acetic acid feed stream fed to the hydrogenation reactor can comprise other carboxylic acids and anhydrides, as well as aldehydes and/or ketones such as acetaldehyde and acetone. Preferably, the 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 compounds can also be hydrogenated in the process of the invention. In some embodiments, the presence of certain carboxylic acids, such as the presence of propionic acid or its anhydride, may be beneficial for the production of propanol. Water may also be present in the acetic acid feed at levels up to 25% by weight, such as up to 20% by weight of water or up to 10% by weight of water. Preferably, methyl iodide is substantially absent from the acetic acid feed stream.

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. In order to carry out the reaction in the gas phase, the temperature in the system should be controlled not lower than the dew point of acetic acid. 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 vapor 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.

In some embodiments, the reactor can include a variety of configurations employing a fixed bed reactor or a fluidized bed reactor. 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 group can be used as the reactor, or a series of reactors with or without heat exchange, quenching, 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 reactant, typically in vapor form, is passed over the surface or interior of the catalyst. Other reactors may be employed, such as fluidized or bunk bed reactors. In some cases, the hydrogenation catalyst can be used with inert materials. To regulate 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 in the reactor 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 ranges, the GHSV may range from 50/hour to 50,000/hour, such as from 500/hour to 30,000/hour, from 1,000/hour to 10,000/hour, or from 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 to form acetic acid to ethanol is preferably carried out in the reactor 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 IB, IIB, IIIB, IVB, VB, VIB, VIIB, VIIIB transition metals, lanthanide metals, lanthanide metals or selected from the group IIIA Metal of any of the IVA, VA, and VIA families. 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 US 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, osmium, iridium, platinum, titanium, zinc, chromium, lanthanum, 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 further comprises 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. Better use of modified support In the embodiment, 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 from 1 to 8% by weight. 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 for forming 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 modifier includes these groups 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; average pore size determined by mercury pore analysis The 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 ceria sphere from Sud Chemie 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. The support 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 and desired ethanol selectivity and yield in the reactor. 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 percentage of methanol in the feed. For example, acetic acid can have a conversion of greater than 40%, such as greater than 50%, greater than 70%, or greater than 90% conversion. The conversion rate can vary widely, and can range from 40% to 70% in some embodiments, and from 85% to 99% in other embodiments.

The selectivity is expressed as the percentage of moles 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 mole % of the converted acetic acid is converted to ethanol, we call the ethanol selectivity 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 of ethanol in the reactor is at least 80%, such as at least 85% or at least 88%. The preferred embodiment of the hydrogenation process also has a low 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 of 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 mixture produced by the reactor typically contains acetic acid, ethanol, and water prior to any subsequent processing, such as purification and separation. An exemplary compositional range of the crude ethanol mixture is shown in Table 2. The "others" referred to in Table 2 may include, for example, esters, ethers, aldehydes, ketones, alkanes, and carbon dioxide.

In one embodiment, the crude ethanol mixture 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 terms of ranges, the acetic acid concentration of Table 2 may range from 0.1% by weight to 20% by weight, such as from 0.2% by weight to 15% by weight, 0.5. It is in the range of % by weight to 10% by weight or 1% by weight to 5% by weight. In embodiments having a lower 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%.

Ethanol can be recovered using several different techniques. In Figures 2-4, the hydrogenation section 200 utilizes three distillation columns 231, 241, 251 and/or an optional fourth distillation column 261 to separate the crude ethanol mixture. Other separation systems are also available for use in embodiments of the invention, as shown in Figures 5 and 6.

In each of the figures, hydrogenation section 200 includes a reaction zone 210 and a separation zone 230. Acetic acid may be supplied from the acetic acid intermediate in line 143 and/or optionally from raffinate 193 and fed via line 205. As described above, the acetic acid fed to the hydrogenation section 200 is substantially free of methyl iodide. Hydrogen is also fed to evaporator 201 via line 204 to produce a vapor feed stream in line 203 and feed the vapor feed stream to reactor 211. In one embodiment, the feed lines including the streams fed from the oxonation section 100 can be combined and combined into the evaporator 201. The temperature of the vapor feed stream in line 203 is preferably from 100 ° C to 350 ° C, such as from 120 ° C to 310 ° C or from 150 ° C to 300 ° C. Any unvaporized feed is removed from evaporator 201 and can be extracted to form discharge stream 202. Further, although the display line 203 is introduced into the top of the reactor 211, the line 203 may be introduced into the side, upper portion or bottom portion of the reactor 211.

Reactor 211 contains a carboxylic acid which is hydrogenated, preferably acetic acid, and a catalyst which hydrogenates other carboxyl compounds such as ethyl acetate and acetaldehyde. In one embodiment, one or more guard beds (not shown) may be used upstream of the reactor, optionally upstream of the evaporator 201, 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. During the hydrogenation process, a crude ethanol mixture stream is withdrawn from reactor 211 via line 212, which is preferably continuously withdrawn from reactor 211.

The crude ethanol mixture stream in line 212 can be condensed and fed into separator 221, which in turn provides vapor stream 223 and liquid stream 222. In some embodiments, the separator 221 can comprise a flash column or a knockout pot. The separator 221 can operate at a temperature of 20 ° C to 250 ° C, for example, at a temperature of 30 ° C to 225 ° C or 60 ° C to 200 ° C. The pressure of the separator 221 may be 50 kPa to 2,000 kPa, for example, 75 kPa to 1,500 kPa or 100 to 1,000 kPa. Optionally, a crude mixture of ethanol in line 212 can be passed through one or more membranes to separate hydrogen and/or other non-condensable gas.

The vapor stream 223 exiting the separator 221 can contain hydrogen and hydrocarbons that can be purged off and/or returned to the reaction zone 210. Upon returning to reaction zone 210, vapor stream 223 can be combined with hydrogen feed 204 and fed together into evaporator 201. In some embodiments, the returned vapor stream 223 can be first compressed and then combined with the hydrogen feed 204.

The liquid stream 222 is extracted by the separator 221 and is drawn into the side of the first distillation column 231, and the first distillation column 231 is also referred to as an "acid separation distillation column". In one embodiment, the contents of liquid stream 222 are substantially similar to the crude mixture of ethanol obtained from the reactor, with the difference that the composition does not have hydrogen, carbon dioxide, methane, and/or ethane, which are all separated by separator 221. Remove. Thus, liquid stream 222 can also be referred to as a crude mixture of ethanol. Exemplary components of liquid stream 222 are shown in Table 3. It should be understood that liquid stream 222 may contain other components not listed in Table 3.

The content indicated as less than (<) in the tables of the present specification is preferably absent, and if present, may be present in minor amounts or present in an amount greater than 0.0001% by weight.

The "other esters" in Table 3 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 3 may include, but are not limited to, diethyl ether, methyl ethyl ether, isobutyl ethyl ether or a mixture thereof. The "other alcohols" in Table 3 may include, but are not limited to, methanol, isopropanol, n-propanol, n-butanol or a mixture thereof. In an embodiment The liquid stream 222 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 mixture of ethanol in line 212 or liquid stream 222 can be further fed to an esterification reactor, a hydrogenolysis reactor, or a combination thereof. The esterification reactor is used to consume residual acetic acid in the crude ethanol mixture to further reduce the amount of acetic acid that needs to be removed. Hydrogenolysis can be used to convert ethyl acetate in the crude ethanol mixture to ethanol.

In a preferred embodiment, liquid stream 222 is introduced into the lower portion of first distillation column 231, for example, the lower half or lower third portion. In the first distillation column 231, if acetic acid, a part of water and other heavy components are present, they are transferred from the composition into the line 232, and they are extracted and preferably continuously extracted to become a residue. . Some or all of the residue may be returned and/or recycled back to reaction zone 210 via line 232. Recirculating the acetic acid in line 232 to evaporator 201 can reduce the amount of heavy components that need to be purged by the blow in evaporator 201. Reducing the amount of heavy components that are removed can increase process efficiency while reducing by-products. The first distillation column 231 also forms an overhead which is withdrawn from line 233 and which can be condensed and refluxed, for example, having a reflux ratio of from 10:1 to 1:10, for example from 3:1 to 1:3 Or return it from 1:2 to 2:1. The distillate in line 233 contains primarily ethanol, as well as water, ethyl acetate, acetaldehyde and/or diethyl acetal. For example, the distillate may comprise from 20 to 75% by weight ethanol and from 10 to 40% by weight ethanol. Preferably, the concentration of acetic acid in the distillate is less than 2% by weight, such as less than 1% by weight or less than 0.5% by weight.

In one embodiment, the pressure of the first distillation column 231 may range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa. When the distillation column 231 is operated under standard atmospheric pressure, the temperature of the residue discharged into the line 232 is preferably from 95 ° C to 120 ° C, for example, from 110 ° C to 117 ° C or from 111 ° C to 115 ° C. The temperature of the distillate discharged into the line 233 is preferably from 70 ° C to 110 ° C, for example from 75 ° C to 95 ° C or from 80 ° C to 90 ° C.

As shown, the first distillate in line 233 is directed to second distillation column 241, preferably to the intermediate portion of distillation column 241, and second distillation column 241 is also referred to as "light fraction distillation." tower". Preferably, the second distillation column 241 is an extractive distillation column, and the extractant is added to the second distillation column 241 via a line 244. The extractive distillation method is a method of separating a similar boiling point component such as an azeotrope by distilling a feed in the presence of an extractant. The extractant preferably has a boiling point higher than the feed component to be separated Boiling point. In a preferred embodiment, the extractant comprises primarily water. As previously described, the first distillate in line 233 is fed to a second distillation column 241 which contains ethanol, water and ethyl acetate. These compounds tend to form binary azeotropes and ternary azeotropes to reduce separation efficiency. In one embodiment, the extractant comprises a portion of a third residue in line 252. Preferably, the recycled third residue in line 244 is fed to second distillation column 241 at a higher level than the first distillate in line 233. In one embodiment, the recycled third residue is fed to the second distillation column 241 in the line 244 near the top, or fed into, for example, the feed in line 244 or from the top stream of the condensation column. Below the return line. In the tray distillation column, the third residue in line 244 is continuously fed into the top of the second distillation column 241 near the top so that an appreciable amount of the third residue is present on all of the trays below. phase. In another embodiment, the extractant is fed to the second distillation column 241 from a source external to the process. Preferably, the extractant comprises water.

Preferably, the water in the extractant is at least 0.5:1, such as at least 1:1 or at least 3:1, relative to the molar amount of ethanol in the second distillation column feed. In terms of range, the preferred molar ratio may range from 0.5:1 to 8:1, such as from 1:1 to 7:1 or from 2:1 to 6.5:1. A higher molar ratio can be used, but the return is diminishing from the viewpoint that the amount of ethyl acetate in the second distillate increases and the concentration of ethanol in the distillate of the second distillation column decreases. of.

In an embodiment, an additional extractant may be added to the second distillation column 241, such as water from an external source, 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 Diethylene triamine, hexamethylenediamine, and 1,3-diaminopentane, alkylated thiophene, dodecane, tridecane, tetradecane, and chlorinated paraffin. Some suitable extractants include those described in U.S. Patent Nos. 4,379,028, 4,569,726, 5,993, 610, and 6, 375, 807, the entire disclosures of Additional extractant can be combined with the recycled third residue in line 252 and fed together into second distillation column 241. Additional extractants may also be added to the second distillation column 241 individually. In one aspect, the extractant comprises an extractant from an external source, such as water, and no extractant is derived from the third residue.

The second distillation column 241 may be a tray or a packed distillation column. In one embodiment, the second distillation column 241 is a tray distillation column having 5 to 120 trays, for example, having 15 to 80 trays or 20 to 70 trays. The temperature of the second distillation column 241 under normal pressure may vary. The second distillation column 241 can be operated at a pressure in the range of 0.1 kPa to 510 kPa, for example, 1 kPa to 475 kPa or 1 kPa to 375 kPa. In one embodiment, the second residue discharged into line 242 is preferably at a temperature of from 60 ° C to 90 ° C, such as from 70 ° C to 90 ° C or from 80 ° C to 90 ° C. The temperature of the second distillate discharged into the line 243 from the second distillation column 241 is preferably from 50 ° C to 90 ° C, for example from 60 ° C to 80 ° C or from 60 ° C to 70 ° C.

The second residue in line 242 contains ethanol and water. The second residue may comprise less than 3% by weight of ethyl acetate, such as less than 1% by weight of ethyl acetate or less than 0.5% by weight of ethyl acetate. The second distillate in line 243 comprises ethyl acetate, acetaldehyde and/or diethyl acetal. In addition, a small amount of ethanol may be present in the second distillate. Preferably, the weight of ethanol in the second residue relative to the ethanol in the second distillate is at least 3:1, such as at least 6:1, at least 8:1, at least 10:1 or at least 15:1.

All or part of the third residue is recycled to the second distillation column. In one embodiment, all of the third residue can be recycled until the process reaches a steady state, at which point a portion of the third residue is recycled while the remainder is purged from the system. As the third residue is recycled, the concentration of ethanol in the composition of the second residue tends to decrease. Since the third residue is recycled, the composition of the second residue comprises less than 30% by weight of ethanol, for example less than 20% by weight or less than 15% by weight of ethanol. Preferably, the second residue comprises predominantly water. Despite this effect, the extractive distillation step advantageously reduces the amount of ethyl acetate fed to the third distillation column 251, which is highly advantageous in the final preparation of a high purity ethanol product.

As shown, the second residue from the second distillation column 241 and containing ethanol and water is fed to the third distillation column 251 via line 242, and the third distillation column 251 is also referred to as a "product distillation column". . More preferably, the second residue located in the line 242 is introduced into the lower portion of the third distillation column 251, for example, the lower half or lower third portion. The third distillation column 251 recovers ethanol, which is preferably substantially pure to the organic impurities except for the azeotropic water content, and becomes a distillate in the line 253. As shown in Fig. 2, the distillate of the third distillation column 251 is preferably refluxed, for example, having a reflux ratio of 1:10 to 10:1, for example 1:3 to 3:1 or 1: 2 to 2:1. The third residue in line 252 contains primarily water, preferably returned to second distillation column 241 for use as the extractant. In one embodiment, the first portion of the third residue is recycled to the second distillation column in line 244, while the second portion is purged and removed from the system via line 254. In one embodiment, once the process reaches a steady state, the water of the second portion to be purged is substantially similar to that produced in the hydrogenation of acetic acid. The amount of water. In one embodiment, a portion of the third residue is available for hydrolysis of any other stream, such as one or more streams containing ethyl acetate. In one embodiment, the third residue in line 252 is withdrawn from third distillation column 251 at a temperature above the operating temperature of second distillation column 241. Preferably, the third residue in line 252 is integrated to heat one or more other streams, or it may be reboiled before returning to second distillation column 241.

Although the third residue can be directly recycled to the second distillation column 241, it is also possible, for example, by storing some or all of the third residue in a storage tank (not shown) or at one or more The third residue is treated in a distillation column (not shown) to further separate any minor components such as aldehydes, high molecular weight alcohols or esters, and the third residue is returned indirectly.

Further, in some embodiments, a portion of the third residue can be directed to the PRS unit 150 of the carbonylation process 100 to extract the derivative stream 163 via line 255.

The third distillation column 251 is preferably a tray distillation column. In one embodiment, the third distillation column 251 can operate at a pressure of 0.1 kPa to 510 kPa, for example, at a pressure of 1 kPa to 475 kPa or 1 kPa to 375 kPa. The temperature of the third distillate discharged into the line 253 at normal pressure is preferably from 60 ° C to 110 ° C, for example from 70 ° C to 100 ° C or from 75 ° C to 95 ° C. The temperature of the third residue in line 252 is preferably from 70 ° C to 115 ° C, such as from 80 ° C to 110 ° C or from 85 ° C to 105 ° C.

The amount of any compound derived from the feed or the reaction crude product remaining in the third distillate after the distillation process is usually less than 0.1% by weight based on the total weight of the third distillate composition, for example Less than 0.05% by weight or less than 0.02% by weight. In one embodiment, one or more side streams can remove impurities from any of the distillation columns in the system. It is preferred to remove impurities from the third distillation column 251 using at least one side stream. Impurities can be purged and/or retained within the system. The composition of the ethanol product obtained from the third distillate in Figure 2 is shown in Table 5 below.

The third distillate in line 253 can be further purified using one or more additional separation systems, such as a distillation column, adsorption unit, membrane or molecular sieve, to form an anhydrous ethanol product stream, i.e., "completed anhydrous ethanol." Suitable adsorption units include pressure swing adsorption units or thermal swing adsorption units.

Returning to the second distillation column 241, the second distillate is preferably refluxed as shown in Fig. 2, and the reflux ratio is 1:10 to 10:1, for example 1:5 to 5:1 or 1:3 to 3:1. The second distillate in line 243 can be purged or recycled to reaction zone 210. At least a portion of the second distillate in line 243 may be further processed in an optional fourth distillation column 261, and fourth distillation column 261 is also referred to as It is "acetaldehyde removal distillation column". In the optional fourth distillation column 261, the second distillate is separated into a fourth distillate containing acetaldehyde in the line 263, and a fourth residue containing ethyl acetate in the line 262. The fourth distillate is preferably refluxed at a reflux ratio of 1:20 to 20:1, for example 1:15 to 15:1 or 1:10 to 10:1, and a portion of the fourth distillate is returned Reaction zone 210. For example, the fourth distillate can be combined with the acetic acid feed, added to the evaporator 201, or added directly to the reactor 211. Preferably, the fourth distillate is fed with acetic acid in feed line 205. Without being bound by theory, since acetaldehyde can be hydrogenated to form ethanol, recycling the acetaldehyde-containing stream to the reaction zone increases the yield of ethanol and reduces the production of by-products and waste. In another embodiment, acetaldehyde can be collected and utilized with or without further purification to make useful products including, but not limited to, n-butanol, 1,3-butanediol, and/or croton. Aldehydes and derivatives.

The fourth residue of the optional fourth distillation column 261 can be purged by blowing through line 262. The fourth residue mainly comprises ethyl acetate and ethanol, which are suitable as solvent mixtures or for the production of esters. In a preferred embodiment, acetaldehyde is removed from the second distillate in fourth distillation column 261 such that there is no measurable amount of acetaldehyde in the fourth residue of distillation column 261.

The optional fourth distillation column 261 is preferably a tray distillation column as described above, and preferably operates at a higher pressure than normal pressure. In one embodiment, the pressure is from 120 kPa to 5,000 kPa, such as from 200 kPa to 4,500 kPa, or from 400 kPa to 3,000 kPa. In a preferred embodiment, the fourth distillation column 261 can operate at a higher pressure than the pressure of the other distillation columns.

The temperature of the fourth distillate discharged into the line 263 is preferably from 60 ° C to 110 ° C, for example from 70 ° C to 100 ° C or from 75 ° C to 95 ° C. The temperature of the fourth residue in line 262 is preferably from 70 °C to 115 °C, such as from 80 °C to 110 °C or from 85 °C to 110 °C.

In one embodiment, a portion of the third residue is recycled to line 244 to the second distillation column 241. In one embodiment, the recycle of the third residue further reduces the aldehyde component of the second residue and concentrates the aldehyde component in the second distillate in line 243 for transport to The fourth distillation column 261, in the fourth distillation column 261, the aldehydes can be separated more easily. Due to the recycle of the third residue, the third distillate in line 253, such as the intermediate product stream, has a lower concentration of aldehydes and esters.

While the composition of the third residue may vary depending on the particular separation conditions, in a preferred embodiment, the third residue comprises water and may be referred to herein as a water stream. Exemplary compositions of the third distillate and the third residue (water stream) are shown in Table 4 below. It should be understood that the distillate can also be To contain other ingredients not listed, such as ingredients in the feed.

A portion of the third residual stream is optionally directed to the carbonylation system 100 as an extraction medium.

Figure 5 shows another exemplary separation system having a reaction zone 210 similar to that of Figures 2-4 and producing a liquid stream 222, such as a crude mixture of ethanol, for further separation. In a preferred embodiment, the reaction zone 210 of Figure 5 operates at a conversion of acetic acid above 70%, such as a conversion of greater than 85% or a conversion of greater than 90%. Thus, the concentration of acetic acid in liquid stream 222 can be low. Derivatized stream 163 and acetic acid feed 132 are also fed to reaction zone 210 in a similar manner as in Figures 2-4.

Liquid stream 222 is fed to first distillation column 271 to produce first distillate 273 and first residue 272. The liquid stream 222 may be introduced to the intermediate portion or the lower portion of the first distillation column 271, and the first distillation column 271 is also referred to as an acid-water distillation column. In one embodiment, no entrainers are added to the first distillation column 271. Water and acetic acid, together with any other heavy components present, are removed from the liquid stream 222 and withdrawn, and preferably continuously withdrawn, to become the first residue in line 272. Preferably, a substantial portion of the water of the crude ethanol mixture fed to the first distillation column 271 can be transferred to the first residue, for example up to about 75% or about 90% of the water from the crude ethanol mixture is transferred to the first Residue. In one embodiment, 30 to 90% of the water in the crude ethanol mixture is transferred to the residue, for example 40 to 88% water or 50 to 84% water is transferred to the residue.

When the first distillation column 271 is operated at about 170 kPa, the temperature of the residue discharged into the line 272 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 273 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 271 may range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa.

In addition to ethanol and other organics, the first distillate in line 273 also contains some water. In terms of ranges, the concentration of water in the first distillate in line 273 is preferably from 4% to 38% by weight, such as from 7% to 32% by weight or from 7 to 25% by weight. A portion of the first distillate in line 275 can be condensed and refluxed, for example, having a reflux ratio of 10:1 to 1:10, such as 3:1 to 1:3 or 1:2 to 2: 1. It will be appreciated that the reflux ratio may vary with the number of stages, the feed location, the efficiency of the distillation column, and/or the composition of the feed. Operating at a reflux ratio above 3:1 may be less desirable as more energy may be required to operate the first distillation column 271. The portion of the first distillate that is condensed may also be fed into the second distillation column 291.

As shown, the remainder of the first distillate in line 274 is fed into water separation unit 281. The water separation unit 281 can be an adsorption unit, a membrane, a molecular sieve, an extractive distillation column, or a combination thereof. 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 capable of removing a permeate stream from a stream comprising ethanol and ethyl acetate.

In a preferred embodiment, the water separation unit 281 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 281 can move at least 95% of the water from the portion of the first distillate in line 273 into the water stream 282, and more preferably removes 99% to 99.99% of the water from the first distillate. . All or a portion of the water stream 282 can be returned to the first distillation column 271 in line 284 where water is preferably recovered from the distillation column 271 and into the first residue in line 272. Additionally and alternatively, all or a portion of the water stream 282 can be removed from the hydrogenation system via line 285. The remainder of the first distillate is withdrawn from water separator 281 to form an ethanol mixture stream 283. The ethanol mixture stream 283 can have a low water concentration of less than 10% by weight, such as less than 6% by weight or less than 2% by weight.

In an optional embodiment, all or a portion of one or both of the first residue in line 272 and/or the separated stream in line 285 can be directed to the carbonylation system, as shown in FIG. For use as an extraction medium. In a preferred embodiment, all or part of the first residue and/or tubing 285 is introduced into the PRS 150 of the carbonylation system as an extractant (e.g., stream 184 in Figure 3) for extracting acetaldehyde from a mixture comprising methyl iodide and acetaldehyde.

Preferably, the ethanol mixture stream 283 does not return or reflux to the first distillation column 271. The condensed portion of the first distillate in line 275 can be combined with the ethanol mixture stream 283 to control the concentration of water fed into the second distillation column 291. For example, in some embodiments, the first distillate can be divided into several equal portions, while in other embodiments, all of the first distillate can be condensed or all of the first distillate The treatment can be carried out in a water separation unit. In Figure 5, the condensed portion of line 275 is fed into second distillation column 291 along with ethanol mixture stream 283. In other embodiments, the condensing portion and the ethanol mixture stream 283 in line 275 can be fed to second distillation column 291, respectively. The combined distillate and ethanol mixture has 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 combined water and ethanol mixture may have an overall water concentration of from 0.5 to 15% by weight, such as from 2 to 12% by weight or from 5 to 10% by weight.

The second distillation column 291 in Fig. 5 is also referred to as a "light fraction distillation column" which removes ethyl acetate and acetaldehyde from a first distillate and/or ethanol mixture stream 283 in line 275. Ethyl acetate and acetaldehyde are removed to form a second distillate in line 293, and the ethanol is removed to form a second residue in line 292. Preferably, the recovered ethanol has a low content of ethyl acetate, acetaldehyde and/or acetal, for example less than 1% by weight or more preferably less than 0.5% by weight. The ethanol product from the second residue in Figure 5 is shown in Table 5 below. Preferably, the ethanol product comprises less than 1% by weight of diethyl acetal, such as less than 0.5% by weight or less than 0.01% by weight of diethyl acetal.

The second distillation column 291 may be a tray distillation column or a packed distillation column. In one embodiment, the second distillation column 291 is a tray distillation column having 5 to 120 trays, for example, having 15 to 100 trays or 20 to 90 trays. In one embodiment, the second distillation column 291 operates at a pressure of from 0.1 kPa to 510 kPa, such as from 10 kPa to 450 kPa or from 50 kPa to 350 kPa. Although the temperature of the second distillation column 291 may vary, the temperature of the second residue discharged into the line 292 is preferably from 30 ° C to 75 ° C when at 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 the line 293 is preferably from 20 ° C to 55 ° C, for example from 25 ° C to 50 ° C or from 30 ° C to 45 ° C.

As described above, the total concentration of water fed into the second distillation column 291 is preferably less than 10% by weight. Additional water may be fed to the second distillation when the first distillate and/or ethanol mixture stream 283 in line 275 contains a small amount of water, such as less than 1% by weight or less than 0.5% by weight water. In tower 291, steaming The upper part of the distillation column serves as an extractant. It is preferred to add a sufficient amount of water via the extractant so that the total water concentration fed into the second distillation column 291 is 1 to 10 by weight based on the total weight of all components fed to the second distillation column 291. % water, for example 2 to 6% by weight of water. If the extractant contains water, the water may be obtained from an external source or from an internal return/recycle line of one or more other distillation columns or water separators.

Suitable extractants may also 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, 1 , 3-diaminopentane, alkylated thiophene, dodecane, tridecane, tetradecane, chlorinated paraffin, or a combination thereof. When an extractant is used, the extractant can be recovered using a suitable recovery system, such as another distillation column.

The second distillate in line 293 comprises ethyl acetate and/or acetaldehyde, which is preferably refluxed as shown in Figure 5, for example, having a reflux ratio of 1:30 to 30:1, for example 1:10 to 10:1 or 1:3 to 3:1. In an unillustrated aspect, the second distillate 293 or a portion thereof can be returned to the reactor 211.

In one embodiment, the second distillate in line 293 and/or the second distillate that has been refined, or a portion of one or both of the two streams, may be further separated to produce Containing acetaldehyde stream and ethyl acetate containing stream. For example, an optional fourth distillation column 261 of Figures 2-4 can be utilized to separate the second distillate in line 293. This may allow a portion of the resulting acetaldehyde- or ethyl acetate-containing stream to be recycled to the reactor 211 for additional purge. The purge stream can be used as a source of ethyl acetate and/or acetaldehyde and is of value. In one embodiment, the second distillation column 291 in Figure 5 is preferably operated at a pressure below atmospheric pressure to reduce the energy required to separate ethyl acetate and ethanol.

Another exemplary double distillation column separation process is shown in Figure 6. Derivatized stream 163 and acetic acid feed 132 are also fed to reaction zone 210 in a manner similar to that of Figures 2-4. In this embodiment, the liquid stream 222 is introduced into the upper portion of the first distillation column 301, such as the upper half or one third of the upper portion. In one embodiment, no entrainers are added to the first distillation column 301. In the first distillation column 301, most of the weight of ethanol, water, acetic acid, and other heavy components present are removed from the liquid stream 222 and extracted, and preferably continuously extracted to become a tube. The first residue in the road 302. The first distillation column 301 also generates an overhead which is drawn into the line 303 and condensed and The reflux is carried out, for example, at a reflux ratio of 30:1 to 1:30, for example, a reflux ratio of 10:1 to 1:10 or 1:5 to 5:1. The first distillate in line 303 preferably contains most of the ethyl acetate from liquid line 222. Additionally, the distillate in line 303 may also contain acetaldehyde.

When the distillation column 301 is operated at about 170 kPa, the temperature of the residue discharged into the line 302 is preferably from 70 ° C to 155 ° C, for example, from 90 ° C to 130 ° C or from 100 ° C to 110 ° C. The base of the distillation column 301 can be maintained at a lower temperature by extracting a residual stream containing ethanol, water, and acetic acid, thereby providing an energy saving advantage. The temperature of the distillate discharged into line 303 is preferably from 75 ° C to 100 ° C at 170 kPa, such as from 75 ° C to 83 ° C or from 81 ° C to 84 ° C.

In one embodiment, at the operating temperature of distillation column 301 of Figure 6, most of the water, ethanol, and acetic acid are removed from the residual stream, and only a small amount of ethanol and water are due to the binary azeotrope and three The metaatrope is formed and collected in the distillate stream. The weight ratio of water in the residue in line 302 to water in the distillate in line 303 can be greater than 1:1, such as greater than 2:1. The weight ratio of ethanol in the residue to ethanol in the distillate may be greater than 1:1, such as greater than 2:1.

The acetic acid content of the first residue can vary, depending primarily on the conversion rate in reactor 211. In one embodiment, when the conversion is high, such as above 90%, the acetic acid content of the first residue may be less than 10% by weight, such as less than 5% by weight or less than 2% by weight. In other embodiments, the acetic acid content of the first residue may be greater than 10% by weight when the conversion is low, such as less than 90%.

The distillate is preferably substantially free of acetic acid, for example comprising less than 1000 wppm, less than 500 wppm or less than 100 wppm of acetic acid. The distillate can be purged from the system by blowing or completely or partially recycled to the reactor 211. In some embodiments, the distillate may be further separated, for example, in an optional fourth distillation column 261 in Figures 2-4, to form an acetaldehyde stream and an ethyl acetate stream. Either of these streams can be returned to reactor 211 or separated from the system to become individual products.

In order to recover ethanol, the residue in the line 302 may be further separated in the second distillation column 311, and the second distillation column 311 is also referred to as an "acid separation distillation column". When the acetic acid content in the first residue is more than 1% by weight, for example, more than 5% by weight, an acid separation distillation column can be applied. The first residue in line 302 is directed to second distillation column 311, preferably to the upper portion of distillation column 311, such as the upper half or one-third of the upper portion. The second distillation column 311 produces a second residue comprising acetic acid and water in line 312, and a second distillate containing ethanol in line 313.

The second distillation column 311 may be a tray distillation column or a packed distillation column. In one embodiment, the second steaming The distillation column 311 is a tray distillation column having 5 to 150 trays, for example, 15 to 50 trays or 20 to 45 trays. In some embodiments, the second distillation column 311 of FIG. 6 operates at a pressure in the range of 0.1 kPa to 510 kPa, for example, from 1 kPa to 475 kPa or from 1 kPa to 375 kPa. Under the pressure of Pa.

In the system shown in Fig. 6, it is preferred that the first distillation column 301 is operated under a pressurization because the second distillation column 311 contains an extremely low content of acetaldehyde and/or acetals. In general, the pressure of the second distillation column 311 may range from 0.1 kPa to 510 kPa, such as from 1 kPa to 475 kPa or from 1 kPa to 375 kPa. The temperature of the second residue discharged into the line 312 at normal pressure is preferably from 95 ° C to 130 ° C, for example from 100 ° C to 125 ° C or from 110 ° C to 120 ° C. The temperature of the second distillate discharged into the line 313 is preferably from 60 ° C to 105 ° C, for example from 75 ° C to 100 ° C or from 80 ° C to 100 ° C.

Preferably, the weight of ethanol in the second distillate in line 313 is at least 35:1 relative to the weight of ethanol in the second residue in line 312. In one embodiment, the weight ratio of water in the second residue 312 to water in the second distillate 313 is greater than 2:1, such as greater than 4:1 or greater than 6:1. Further, the weight of acetic acid in the second residue 312 relative to the acetic acid in the second distillate 313 is preferably greater than 10:1, such as greater than 15:1 or greater than 20:1. Preferably, the second distillate in line 313 contains substantially no acetic acid and contains only traces of acetic acid, if contained. Preferably, the second distillate in line 313 is substantially free of ethyl acetate.

In a further embodiment of the invention, the water remaining in the second distillate in line 313 can be removed. Depending on the concentration of water, the ethanol product may be derived from the second distillate in line 313. Some applications, such as industrial ethanol applications, can tolerate the inclusion of water in ethanol products, while other applications such as fuel applications require anhydrous ethanol. The water content of the distillate in line 313 can be close to the azeotrope of water, for example at least 4% by weight, preferably less than 20% by weight, such as less than 12% by weight or less than 7.5% by weight. Water can be removed from the second distillate in line 313 using a number of different separation techniques as described in this specification. Particularly good techniques include the use of distillation columns, membranes, adsorption units, and combinations thereof.

Optionally, all or a portion of the second residue 312 can be introduced into the carbonylation system, as shown in Figures 2-4, for use as an extraction medium. In a preferred embodiment, all or a portion of the second residue 312 is introduced to the PRS 150 of the carbonylation system as an extractant 164 for extracting acetaldehyde from a mixture comprising methyl iodide and acetaldehyde.

In one embodiment, when any residue from the hydrogenation zone 200 comprises primarily acetic acid, For example, when the amount is more than 50% by weight of 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 residues having a lower acetic acid concentration. 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 the reactor. As described above, the resulting water stream can be directed to a carbonylation system for use as an extractant.

In other embodiments, for example, when the second residue comprises less than 50% by weight acetic acid, possible options include one or more of the following: (i) neutralizing the acetic acid, or (ii) Acetic acid reacts with an alcohol. It is also possible to separate the residue containing less than 50% by weight of acetic acid using a weak acid recovery distillation column to which a solvent (optionally as an azeotroping agent) 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 contains less than 10% by weight of 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.

The distillation column shown in the drawings may comprise any distillation column having the ability to exhibit the desired separation and/or purification. For example, in addition to the acid distillation column described above, the other distillation column is preferably a tray distillation column having 1 to 150 trays, for example, 10 to 100 trays, 20 to 95 trays. Or 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.

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. Supply to The heat of 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 show only a single reactor and a single 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. 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 is known 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 of the distillation column. In addition, depending on the scale of the manufacturing process, the feed rate can vary and, if described, can be broadly expressed in terms of feed weight ratio.

The final ethanol product produced by the process of the present invention can be derived from a stream comprising primarily ethanol from the exemplary systems shown in the figures. The 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 completed ethanol composition range is shown in Table 5 below.

The finished ethanol composition of the present invention preferably contains very low amounts, 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 further water separation means are used, the ethanol product can be extracted 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.

The finished ethanol composition prepared in accordance with embodiments of the present invention can be used in a variety of applications including fuels, solvents, chemical materials, pharmaceuticals, detergents, disinfectants, hydrogen fuel transport 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 completed ethanol composition can also be used in the process as a processing solvent for pharmaceutical products, food preparations, dyes, photochemicals, and latex processing.

The completed 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, ethylbenzene, aldehydes, butadiene 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 form ethylene. Any of the conventional dehydration catalysts can be used to dehydrate the ethanol, as described in U.S. Patent Application Publication Nos. 2010/0030002 and 2010/003, the entire disclosures of which are incorporated herein by reference. For example, a zeolite catalyst can be used as a dehydration catalyst. 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.

In order that the invention disclosed in this specification can be understood more efficiently, several examples are provided below. It is to be understood that the examples are for illustrative purposes only and are not to be construed as limiting in any way.

Instance

Example 1

One milliliter of the initial stream containing methyl iodide and acetaldehyde was contacted with 1 ml of the corresponding extractant at 25 °C. The mixture was shaken 5 times and allowed to stand for 5 minutes. The two phases were then separated and the resulting concentration was determined by gas chromatography. As shown in Table 6 below, this process was tested for three different concentrations.

Example 2

The same experimental procedure as in Example 1 was carried out using the concentration 3 of Table 6 above. This process is performed for three different ratios. As shown in Table 7 below, the ratio 1 was such that 0.5 ml of the extractant was contacted with 1 ml of an initial stream containing methyl iodide (MeI) and acetaldehyde (AcH). Proportion 2 is to contact 1 ml of extractant with 1 ml of the initial stream containing methyl iodide and acetaldehyde. Proportion 3 is to bring 3 ml of extractant into contact with 1 ml of the initial stream containing methyl iodide and acetaldehyde.

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. The disclosure of the related art and the disclosure of the references discussed in the Detailed Description of the Invention and the Detailed Description of the Invention are hereby incorporated by reference. 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 description of the embodiments, the embodiments of the other embodiments may be appropriately combined with one or several other embodiments. In addition, it will be apparent to those skilled in the art that the foregoing description is intended to be illustrative and not restrictive.

10‧‧‧Integrated Process / Process

12‧‧‧carbonylation system

14‧‧‧halide extraction process

16‧‧‧Hydrogenation system

18‧‧‧Reactants

20‧‧‧ Carbon monoxide feed

22‧‧‧ acetic acid flow

24‧‧‧Acetic acid intermediate

26‧‧‧Extractant

28‧‧‧Iodine methane flow

30‧‧‧ hydrogen feed

32‧‧‧ethanol product stream

34‧‧‧Water flow

Claims (22)

A process for producing ethanol, the process comprising the steps of: reacting carbon monoxide with at least one reactant in a first reactor comprising a reaction medium to produce a reaction solution comprising acetic acid, wherein the at least one reactant system Selected from the group consisting of methanol, methyl acetate, methyl formate, methyl ether, and mixtures thereof, and wherein the reaction medium comprises water, acetic acid, methyl iodide, and a first catalyst; and at least one hydrophobic extractant Extracting at least a portion of the reaction solution or a derivative thereof to obtain an acetic acid intermediate product substantially free of methyl iodide; introducing the acetic acid intermediate product into the second reactor in the presence of a second catalyst to form a crude ethanol a product; and recovering ethanol from the crude ethanol product. The process of claim 1, wherein the acetic acid intermediate comprises less than 10 wppm of methyl iodide. The process of claim 1, wherein the acetic acid intermediate comprises less than 10 wppm of an alkyl halide. Application of the process as the first item in the scope of patent, wherein the at least one hydrophobic extractant comprising C ₅ to C ₁₆ alkanes. The process of claim 1, wherein the at least one hydrophobic extractant comprises a C ₈ to C ₁₂ alkane. The process of claim 1, wherein the at least one hydrophobic extractant comprises decane, dodecane or a combination thereof. The process of claim 1, wherein the at least one hydrophobic extractant comprises dodecane. The process of claim 1, wherein the extracting step is a multi-stage extraction. A process as recited in claim 1, wherein a raffinate is obtained during the extracting step, and wherein at least a portion of the raffinate is introduced into the first reactor. The process of claim 1, wherein the acetic acid intermediate product does not substantially contain methanol, methyl acetate, methyl formate and/or methyl ether. The process of claim 1, wherein the acetic acid intermediate comprises less than 0.01% by weight of methanol, methyl acetate, methyl formate and/or methyl ether. The process of claim 1, further comprising: flashing the reaction solution to obtain a vapor stream; and wherein the vapor stream is extracted with the hydrophobic extractant to obtain the acetic acid intermediate product. The process of claim 1, further comprising: flashing the reaction solution to obtain a vapor stream; separating the vapor stream in a light fraction distillation column to produce an acetic acid side stream and comprising a Or an overhead stream of a plurality of permanganate reducing compounds, methyl acetate, methanol, water, and methyl iodide; and wherein the acetic acid side stream is extracted with the hydrophobic extractant to obtain the acetic acid intermediate. The process of claim 13, wherein the permanganate reducing compound is selected from the group consisting of acetaldehyde, acetone, methyl ethyl ketone, butyraldehyde, crotonaldehyde, 2-ethyl crotonaldehyde, 2-ethyl A group consisting of butyraldehyde, their aldol condensation products, and mixtures thereof. The process of claim 1, wherein the crude ethanol product does not substantially contain methyl iodide. The process of claim 1, wherein the crude ethanol product comprises less than 10 wppm of methyl iodide. The process of claim 1, wherein the first catalyst is different from the second catalyst. The process of claim 1, wherein the acetic acid intermediate further comprises water in an amount of from 0.15 to 25% by weight. The process of claim 1, further comprising: flashing the reaction solution to obtain a vapor stream; separating the vapor stream in a light fraction distillation column to produce an acetic acid side stream and comprising a Or an overhead stream of a plurality of permanganate reducing compounds, methyl acetate, methanol, water, and methyl iodide; separating the overhead stream into two phases to form an aqueous stream; and extracting the at least one hydrophobic extractant One part of the aqueous stream to obtain an aldehyde-rich stream. The process of claim 19, further comprising: introducing the aldehyde-rich stream into the second reactor in the presence of the second catalyst to produce ethanol, wherein the aldehyde is enriched The stream does not substantially contain methyl iodide. A process for producing ethanol, the process comprising the steps of: reacting carbon monoxide with at least one reactant in a first reactor comprising a reaction medium to produce a reaction solution comprising acetic acid, wherein the at least one reactant system Choose methanol, a group consisting of methyl acetate, methyl formate, methyl ether, and mixtures thereof, and wherein the reaction medium comprises water, acetic acid, methyl iodide, and a first catalyst; the reaction solution is flashed to obtain a vapor stream Extracting the condensed portion of the vapor stream with at least one hydrophobic extractant to obtain an acetic acid intermediate substantially free of methyl iodide; introducing the acetic acid intermediate into the second reactor in the presence of a second catalyst A crude ethanol product is formed; and ethanol is recovered from the crude ethanol product. A process for producing ethanol, the process comprising the steps of: reacting carbon monoxide with at least one reactant in a first reactor comprising a reaction medium to produce a reaction solution comprising acetic acid, wherein the at least one reactant system Selected from the group consisting of methanol, methyl acetate, methyl formate, methyl ether and mixtures thereof, wherein the reaction medium comprises water, acetic acid, methyl iodide and a first catalyst; the reaction solution is flashed Obtaining a vapor stream; separating the vapor stream in a light fraction distillation column to form an acetic acid side stream and a column comprising one or more permanganate reducing compounds, methyl acetate, methanol, water, and methyl iodide a stream, wherein the permanganate reducing compounds are selected from the group consisting of acetaldehyde, acetone, methyl ethyl ketone, butyraldehyde, crotonaldehyde, 2-ethyl crotonaldehyde, 2-ethyl butyraldehyde, and the like, and a group consisting of a mixture thereof; extracting a portion of the acetic acid side stream with at least one hydrophobic extractant to obtain an acetic acid intermediate product substantially free of methyl iodide; The acetic acid intermediate is introduced into the second reactor to form a crude ethanol product; and the ethanol is recovered from the crude ethanol product.