Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/42—Separation; Purification; Stabilisation; Use of additives
  • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
  • C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/14—Fractional distillation or use of a fractionation or rectification column
  • B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/14—Fractional distillation or use of a fractionation or rectification column
  • B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
  • B01D3/324—Tray constructions
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/42—Separation; Purification; Stabilisation; Use of additives
  • C07C51/48—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C53/00—Saturated compounds having only one carboxyl group bound to an acyclic carbon atom or hydrogen
  • C07C53/08—Acetic acid

Definitions

• this invention relates to an improved process for reducing and/or removing precursors of permanganate reducing compounds and alkyl iodides from intermediate streams during the formation of acetic acid by said carbonylation processes.
• halide promoter is not critical.
• the patentees disclose a very large number of suitable promoters, most of which are organic iodides. Most typically and usefully, the reaction is conducted by continuously bubbling carbon monoxide gas through a liquid reaction medium in which the catalyst is dissolved.
• An improvement in the prior art process for the carbonylation of an alcohol to produce the carboxylic acid having one carbon atom more than the alcohol in the presence of a rhodium catalyst is disclosed in commonly assigned U.S. Patent Nos. 5,001,259, issued Mar. 19, 1991; 5,026,908, issued Jun. 25, 1991; and 5,144,068, issued Sep. 1, 1992; and European Patent No. EP 0 161 874 B2, published Jul. 1, 1992.
• acetic acid is produced from methanol in a reaction medium containing methyl acetate, methyl halide, especially methyl iodide, and rhodium present in a catalytically effective concentration.
• the reaction medium employed improves the stability of the rhodium catalyst, i.e. resistance to catalyst precipitation, especially during the product recovery steps of the process. In these steps, distillation for the purpose of recovering the acetic acid product tends to remove from the catalyst the carbon monoxide which in the environment maintained in the reaction vessel, is a ligand with stabilizing effect on the rhodium.
• carbonyl is intended to mean compounds that contain aldehyde or ketone functional groups, which compounds may or may not possess unsaturation. See Catalysis of Organic Reaction, 75, 369-380 (1998), for further discussion on impurities in a carbonylation process.
• the present invention is directed to reducing and/or removing permanganate reducing compounds (PRC's) such as acetaldehyde, acetone, methyl ethyl ketone, butyraldehyde, crotonaldehyde, 2-ethyl crotonaldehyde, and 2-ethyl butyraldehyde and the like, and the aldol condensation products thereof.
• PRC's permanganate reducing compounds
• the present invention also leads to reduction of propionic acid.
• the carbonyl impurities described above such as acetaldehyde, may react with iodide catalyst promoters to form multi-carbon alkyl iodides, e.g., ethyl iodide, propyl iodide, butyl iodide, pentyl iodide, hexyl iodide and the like. It is desirable to remove alkyl iodides from the reaction product because even small amounts of these impurities in the acetic acid product tend to poison the catalyst used in the production of vinyl acetate, the product most commonly produced from acetic acid.
• the present invention is thus also directed to removal of alkyl iodides, in particular C - ⁇ 2 alkyl iodide compounds. Accordingly, because many impurities originate with acetaldehyde, it is a primary objective to remove acetaldehyde from the process so as to reduce the alkyl iodide content.
• Conventional techniques to remove impurities include treating the acetic acid product with oxidizers, ozone, water, methanol, activated-carbon, amines, and the like, which treatment may or may not be combined with distillation of the acetic acid. The most typical purification treatment involves a series of distillations of the final product. It is also known, for example from U.S. Patent No.
• European Patent No. EP 0 487 284 Bl published April 12, 1995, discloses that carbonyl impurities present in the acetic acid product generally concentrate in the overhead from the light ends column. Accordingly, the light ends column overhead is treated with an amine compound (such as hydroxylamine), which reacts with the carbonyl compounds to form oxime derivatives that can be separated from the remaining overhead by distillation, resulting in an acetic acid product with improved permanganate time.
• EP 0 687 662 A2 and U.S. Patent No. 5,625,095 also disclose management of reaction conditions to control the formation of acetaldehyde in the reactor. Although it is stated that formation of by-products such as crotonaldehyde, 2-ethylcrotonaldehyde, and alkyl iodides is reduced by controlling the formation of acetaldehyde, it is also pointed out that management of reaction conditions as proposed increases the formation of propionic acid, an undesirable byproduct. More recently, it has been disclosed in commonly assigned U.S. Patent Nos.
• the present invention provides a process for producing acetic acid that includes the following steps: (a) reacting methanol, methyl acetate, methyl formate or dimethyl ether with carbon monoxide in a suitable reaction medium that includes a catalyst and an organic iodide; (b) separating the products of the reaction into a volatile product phase that contains acetic acid, methyl iodide, water, and permanganate reducing compounds (PRC's), and a less volatile phase containing the catalyst and acetic acid; (c) distilling the volatile product phase to yield a purified product and a first overhead that contains organic iodide, water, acetic acid, and unreacted methanol; (d) distilling at least a portion of the first overhead to produce a second overhead containing methyl iodide, water, C 2 _ ⁇ 2 alkyl iodides, PRC's and dimethyl ether; (e) extracting the second overhead with
• the present invention provides an improved method for separating a mixture containing water, acetic acid, methyl iodide, methyl acetate, methanol, at least one C 2 - ⁇ 2 alkyl iodide and at least one permanganate reducing compound (PRC).
• PRC permanganate reducing compound
• the improved method includes the following steps: (a) distilling the mixture to form a PRC enriched overhead stream containing dimethyl ether; (b) extracting the overhead stream with water and separating therefrom a first aqueous stream containing at least one PRC; and (c) extracting the extracted overhead stream with water and separating therefrom a second aqueous stream containing at least one PRC.
• the overhead stream contains sufficient dimethyl ether to reduce the solubility of methyl iodide in the aqueous extracts.
• the present invention provides an improved method for reduction and/or removal of permanganate-reducing compounds (PRC's) and C 2 - ⁇ 2 alkyl iodide compounds formed in the carbonylation of a carbonylatable material such as methanol, methyl acetate, methyl formate or dimethyl ether to a product of acetic acid.
• PRC's permanganate-reducing compounds
• C 2 - ⁇ 2 alkyl iodide compounds formed in the carbonylation of a carbonylatable material such as methanol, methyl acetate, methyl formate or dimethyl ether to a product of acetic acid.
• the methanol is carbonylated in a reaction medium containing a catalyst and an organic iodide; the products of the carbonylation reaction are phase separated into (1) a volatile phase containing acetic acid product, organic iodide, water, and at least one PRC, and (2) a less volatile phase; and the volatile phase is distilled to yield a purified product and an overhead containing organic iodide, water, acetic acid, and PRC.
• the improvement includes the steps of (a) distilling at least a portion of the overhead to provide a PRC enriched overhead stream containing dimethyl ether; (b) extracting the PRC enriched overhead stream with water and separating therefrom an aqueous waste stream containing PRC's; and (c) extracting the extracted overhead stream with water and separating therefrom a second aqueous waste stream also containing at least one PRC.
• the overhead stream contains sufficient dimethyl ether to reduce the solubility of methyl iodide in the aqueous extracts.
• FIG. 1 illustrates the prior art process, as disclosed in U.S. Patent No. 6,339,171, for the removal of carbonyl impurities from an intermediate stream of the carbonylation process for the production of acetic acid by a carbonylation reaction.
• FIG. 2 illustrates a preferred embodiment of the present invention. While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is intended to cover all modifications, equivalents and alternatives falling within the scope of the invention as defined by the appended claims.
• the purification process of the present invention is useful in any process used to carbonylate methanol (or another carbonylatable material such as methyl acetate, methyl formate or dimethyl ether, or mixtures thereof) to acetic acid in the presence of a Group NIII metal catalyst such as rhodium and an iodide promoter.
• a particularly useful process is the low water rhodium-catalyzed carbonylation of methanol to acetic acid as exemplified in U.S. Patent No. 5,001,259.
• the rhodium component of the catalyst system is believed to be present in the form of a coordination compound of rhodium with a halogen component providing at least one of the ligands of such coordination compound.
• the rhodium component of the catalyst system may be provided by introducing into the reaction zone rhodium in the form of rhodium metal, rhodium salts such as the oxides, acetates, iodides, etc., or other coordination compounds of rhodium, and the like.
• the halogen-promoting component of the catalyst system consists of a halogen compound comprising an organic halide.
• alkyl, aryl, and substituted alkyl or aryl halides can be used.
• the halide promoter is present in the form of an alkyl halide in which the alkyl radical corresponds to the alkyl radical of the feed alcohol, which is carbonylated.
• the halide promoter will include methyl halide, and more preferably methyl iodide.
• the liquid reaction medium employed may include any solvent compatible with the catalyst system and may include pure alcohols, or mixtures of the alcohol feedstock and/or the desired carboxylic acid and/or esters of these two compounds.
• the preferred solvent and liquid reaction medium for the low water carbonylation process is the carboxylic acid product.
• the preferred solvent is acetic acid.
• the desired reaction rates are obtained even at low water concentrations by including in the reaction medium methyl acetate and an additional iodide ion which is over and above the iodide which is present as a catalyst promoter such as methyl iodide or other organic iodide.
• the additional iodide promoter is an iodide salt, with lithium iodide being preferred. It has been found that under low water concentrations, methyl acetate and lithium iodide act as rate promoters only when relatively high concentrations of each of these components are present and that the promotion is higher when both of these components are present simultaneously (U.S. Patent No.
• the concentration of lithium iodide used in the reaction medium of the preferred carbonylation reaction system is believed to be quite high as compared with what little prior art there is dealing with the use of halide salts in reaction systems of this sort.
• the absolute concentration of iodide ion content is not a limitation on the usefulness of the present invention.
• the carbonylation reaction of methanol to acetic acid product may be carried out by contacting the methanol feed, which is in the liquid phase, with gaseous carbon monoxide bubbled through a liquid acetic acid solvent reaction medium containing the rhodium catalyst, methyl iodide promoter, methyl acetate, and additional soluble iodide salt, at conditions of temperature and pressure suitable to form the carbonylation product.
• a liquid acetic acid solvent reaction medium containing the rhodium catalyst, methyl iodide promoter, methyl acetate, and additional soluble iodide salt
• any metal iodide salt, or any iodide salt of any organic cation, or quaternary cation such as a quaternary amine or phosphine or inorganic cation can be used provided that the salt is sufficiently soluble in the reaction medium to provide the desired level of the iodide.
• the iodide is added as a metal salt, preferably it is an iodide salt of a member of the group consisting of the metals of Group IA and Group IIA of the periodic table as set forth in the "Handbook of Chemistry and Physics" published by CRC Press, Cleveland, Ohio, 2002-03 (83rd edition).
• alkali metal iodides are useful, with lithium iodide being preferred.
• the additional iodide over and above the organic iodide promoter is present in the catalyst solution in amounts of from about 2 to about 20 wt %, the methyl acetate is present in amounts of from about 0.5 to about 30 wt %, and the lithium iodide is present in amounts of from about 5 to about 20 wt %.
• the rhodium catalyst is present in amounts of from about 200 to about 2000 parts per million (ppm). Typical reaction temperatures for carbonylation will be approximately 150 to about 250°C, with the temperature range of about 180 to about 220°C being the preferred range.
• the carbon monoxide partial pressure in the reactor can vary widely but is typically about 2 to about 30 atmospheres, and preferably, about 3 to about 10 atmospheres. Because of the partial pressure of by-products and the vapor pressure of the contained liquids, the total reactor pressure will range from about 15 to about 40 atmospheres.
• a typical reaction and acetic acid recovery system that is used for the iodide-promoted rhodium catalyzed carbonylation of methanol to acetic acid is shown in FIG. 1 and includes a liquid phase carbonylation reactor, flasher, and a methyl iodide acetic acid light ends column 14 which has an acetic acid side stream 17 which proceeds to further purification. The reactor and flasher are not shown in FIG. 1.
• the carbonylation reactor is typically either a stirred vessel or bubble-column type within which the reacting liquid or slurry contents are maintained automatically at a constant level.
• This reactor there are continuously introduced fresh methanol, carbon monoxide, sufficient water as needed to maintain at least a finite concentration of water in the reaction medium, recycled catalyst solution from the flasher base, a recycled methyl iodide and methyl acetate phase, and a recycled aqueous acetic acid phase from an overhead receiver decanter of the methyl iodide acetic acid light ends or splitter column 14.
• Distillation systems are employed that provide means for recovering the crude acetic acid and recycling catalyst solution, methyl iodide, and methyl acetate to the reactor.
• carbon monoxide is continuously introduced into the carbonylation reactor just below the agitator, which is used to stir the contents.
• the gaseous feed is thoroughly dispersed through the reacting liquid by this stirring means.
• a gaseous purge stream is vented from the reactor to prevent buildup of gaseous by-products and to maintain a set carbon monoxide partial pressure 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.
• Liquid product is drawn off from the carbonylation reactor at a rate sufficient to maintain a constant level therein and is introduced to the flasher.
• the catalyst solution is withdrawn as a base stream (predominantly acetic acid containing the rhodium and the iodide salt along with lesser quantities of methyl acetate, methyl iodide, and water), while the vapor overhead stream of the flasher contains largely the product acetic acid along with methyl iodide, methyl acetate, and water.
• Dissolved gases exiting the reactor and entering the flasher consist of a portion of the carbon monoxide along with gaseous by products such as methane, hydrogen, and carbon dioxide and exit the flasher as part of the overhead stream.
• the overhead stream is directed to the light ends or splitter column 14 as stream 26. It has been disclosed in U.S. Patent Nos. 6,143,930 and 6,339,171 that there is a higher concentration, about 3 times, of the PRC's and in particular acetaldehyde content in the light phase than in the heavy phase stream exiting column 14. Thus, in accordance with the present invention, stream 28, containing PRC's is directed to an overhead receiver decanter 16 where the light ends phase, stream 30, is directed to distillation column 18.
• the present invention may broadly be considered as an improved process for distilling PRC's, primarily aldehydes and alkyl iodides, from a vapor phase acetic acid stream, such as the overhead from a light ends distillation column or a combined light-ends/drying column.
• a vapor phase acetic acid stream such as the overhead from a light ends distillation column or a combined light-ends/drying column.
• the vapor phase stream is distilled and then twice extracted to remove PRC's.
• An especially preferred method of removing aldehydes and alkyl iodides from a first vapor phase acetic acid stream, and reducing levels of propionic acid in the product includes the following steps: a) condensing the first vapor phase acetic acid stream in a first condenser and biphasically separating it to form a first heavy liquid phase product and a first light liquid phase product; b) distilling the first light liquid phase product in a first distillation column to form a second vapor phase acetic acid product stream which is enriched with aldehydes and alkyl iodides with respect to said first vapor phase acetic acid stream; c) condensing the second vapor phase stream in a second condenser to form a second liquid phase product; d) distilling the second liquid phase product in a second distillation column to form a third vapor phase stream; e) condensing the third vapor phase stream and extracting the condensed stream with water to remove residual acetalde
• FIG. 1 An embodiment of the prior art as disclosed in U.S. Patent No. 6,339,171 is shown in FIG. 1.
• the first vapor phase acetic acid stream (28) contains methyl iodide, methyl acetate, acetaldehyde and other carbonyl components.
• This stream is then condensed and separated (in vessel 16) to separate the heavy phase product containing the larger proportion of catalytic components—which is recirculated to the reactor (not shown in FIG. 1), and a light phase (30) containing acetaldehyde, water, and acetic acid.
• Either phase of the light ends overhead may be subsequently distilled to remove the PRC's and primarily the acetaldehyde component of the stream, although it is preferred to remove PRC's from the light phase (30) because it has been found that the concentration of acetaldehyde is somewhat greater in that phase.
• the distillation is carried out in two stages; but it will be appreciated that the distillation may be performed in a single column as well.
• the light phase (30) is directed to column 18, which serves to form a second vapor phase (36) enriched in aldehydes and alkyl iodides with respect to stream 28.
• Stream 36 is condensed (vessel 20) to form a second liquid phase product.
• the second liquid phase (40) containing acetaldehyde, methyl iodide, methanol, and methyl acetate is directed to a second distillation column (22) wherein the acetaldehyde is separated from the other components.
• This inventive process has been found to reduce and/or remove at least 50% of the alkyl iodide impurities found in an acetic acid stream. It has also been shown that acetaldehyde and its derivatives is reduced and/or removed by at least 50%), most often greater than 60%>. As a result, it is possible to keep the concentration of propionic acid in the acetic acid product below about 400 parts per million by weight, preferably below about 250 parts per million.
• stream 28 From the top of the light ends or splitter column 14, vapors are removed via stream 28, condensed, and directed to vessel 16. The vapors are chilled to a temperature sufficient to condense and separate the condensable methyl iodide, methyl acetate, acetaldehyde and other carbonyl components, and water into two phases.
• a portion of stream 28 includes noncondensable gases such as carbon dioxide, hydrogen, and the like and can be vented as shown in stream 29 on FIG. 1.
• stream 29 on FIG. 1 Also leaving overhead receiver decanter 16, but not illustrated in FIG. 1, is the heavy phase of stream 28. Ordinarily this heavy phase is recirculated to the reactor, but a slip stream, generally a small amount, e.g., 25 vol.
• %>, preferably less than about 20 vol. %, of the heavy phase may also be directed to a carbonyl treatment process and the remainder recycled to the reactor or reaction system.
• This slip stream of the heavy phase may be treated individually or combined with the light phase (stream 30) for further distillation and extraction of carbonyl impurities.
• the light phase (stream 30) is directed to distillation column 18.
• a portion of stream 30 is directed back to the light ends column 14 as reflux stream 34.
• the remainder of stream 30 enters column 18 as stream 32 in about the middle of the column.
• Column 18 serves to concentrate the aldehyde components of stream 32 into overhead stream 36 by separating water and acetic acid from the lighter components.
• First distillation column 18 preferably contains approximately 40 trays, and temperature ranges therein from about 283°F (139.4°C) at the bottom to about 191°F (88.3°C) at the top of the column. Exiting the bottom of 18 is stream 38 containing approximately 70%) water and 30%> acetic acid.
• Stream 38 is processed, generally cooled utilizing a heat exchanger, is recycled to the light ends column overhead decanter 16 via streams 46, 48 and ultimately to the reactor or reaction system. It has been found that recycling a portion of stream 38 identified as stream 46 back through decanter 16 increases efficiency of the inventive process and allows for more acetaldehyde to be present in the light phase, stream 32.
• Stream 36 has been found to have approximately seven times more aldehyde content when stream 38 is recycled through decanter 16 in this manner.
• stream 36 containing PRC's and in particular acetaldehyde, methyl iodide, methyl acetate, and methanol, and alkyl iodides.
• Stream 36 is then directed to an overhead receiver 20 after it has been chilled to condense any condensable gases present.
• Exiting overhead receiver 20 is stream 40 containing acetaldehyde, methyl iodide, methyl acetate, and methanol.
• a portion of stream 40 is returned to column 18 as reflux stream 42. The remainder of stream 40 enters second distillation column 22 close to the bottom of the column.
• Column 22 serves to separate the majority of the acetaldehyde from the methyl iodide, methyl acetate, and methanol in stream 40.
• column 22 contains about 100 trays and is operated at a temperature ranging from about 224°F (106.6°C) at the bottom to about 175°F (79.4°C) at the top.
• column 22 contains structured packing in place of trays.
• the preferred packing is a structured packing with an interfacial area of about 65 ft /ft , preferably made from a metallic alloy like 2205 or other like packing material, provided it is compatible with the compositions to be purified in the column.
• an inhibitor is needed, preferably in column 22, to reduce the formation of these impurities, i.e., metaldehyde and paraldehyde and higher molecular weight polymers of acetaldehyde (AcH).
• Inhibitors generally consist of Ci-io alkanols, preferably methanol; water; acetic acid and the like used individually or in combination with each other or with one or more other inhibitors.
• Stream 46 which is a portion of column 18 residue and a slip stream of stream 38, contains water and acetic acid and hence can serve as an inhibitor. As shown in FIG. 1, stream 46 splits to form streams 48 and 50.
• Stream 50 is added to column 22 to inhibit formation of metaldehyde and paraldehyde impurities and higher molecular weight polymers. Since the residue of second column 22 is recycled to the reactor, any inhibitors added must be compatible with the reaction chemistry. It has been found that small amounts of water, methanol, acetic acid, or a combination thereof, do not interfere with the reaction chemistry and practically eliminate the formation of polymers of acetaldehyde. Stream 50 is also preferably employed as an inhibitor since this material does not change the reactor water balance. Although water is not particularly preferred as an inhibitor, other important advantages are obtained by adding water to column 22 as will be explained below. Exiting the top of column 22 is stream 52 containing PRC's.
• Stream 52 is directed to a condenser and then to overhead receiver 24. After condensation, any non-condensable materials are vented from receiver 24; the condensed materials exit receiver 24 as stream 54.
• Stream 56 a slip stream of stream 54, is used as reflux for column 22. Exiting the bottom of column 22 is stream 44 containing methyl iodide, methanol, methyl acetate, methanol and water. This stream is combined with stream 72, which will be described below, and directed to the reactor. It is important for the extraction mechanism that the overhead stream of column 22 remain cold, generally at a temperature of about 13°C. This stream may be obtained or maintained at about 13°C by conventional techniques known to those of skill in the art, or any mechanism generally accepted by the industry.
• stream 58 is preferably sent through a condenser/chiller (now stream 62) and then to a first extractor 27.
• extractor 27 PRC's and alkyl iodides are extracted with water, preferably water from an internal stream so as to maintain water balance within the reaction system.
• methyl iodide separates from the aqueous PRC's and alkyl iodide phase.
• a mixer-settler with a water-to-feed ratio of about 2 is employed.
• the aqueous extract stream 64 leaves the extractor 27 from the top thereof. This PRC-rich, and in particular, acetaldehyde-rich aqueous phase is directed to waste treatment.
• raffinate stream 66 containing methyl iodide.
• Raffinate stream 66 is extracted with additional water in a second extractor 25.
• PRC's and alkyl iodides are extracted with water, preferably water from an internal stream so as to maintain water balance within the reaction system.
• methyl iodide separates from the aqueous PRC's and alkyl iodide phase.
• a mixer-settler with a water-to-fee'd ratio of about 1 is employed.
• the aqueous extract stream 70 leaves the extractor from the top thereof.
• This PRC-rich, and in particular, acetaldehyde- rich aqueous phase is directed to waste treatment.
• raffinate stream 72 containing methyl iodide This stream is normally recycled to the reaction system and ultimately to the reactor. It will be immediately apparent to one of ordinary skill in the art that additional extraction stages may be added as desired to further increase the fraction of methyl iodide recovered from the acetaldehyde-rich overhead from column 22. It will also be apparent that additional variations are possible in which a single water stream passes through the extraction stages in series rather than using fresh water in each stage.
• the multistage extraction as described herein may also be accomplished using a packed-bed (continuous contacting) extractor having a suitable number of theoretical stages in place of equipment having discrete stages.
• a packed-bed (continuous contacting) extractor having a suitable number of theoretical stages in place of equipment having discrete stages.
• methyl iodide is an especially costly component of the reaction system, it is highly desirable to minimize the amount of methyl iodide that is removed from the process as waste so as to reduce the quantity of fresh methyl iodide that must be fed to the reactor.
• DME dimethyl ether
• a further aspect of the present invention includes the step of injecting DME into the process upstream of extractor 27, for example into stream 62, to reduce the loss of methyl iodide into the aqueous extract streams 64 and 70.
• the required quantity of DME in stream 62 can be obtained by adding water to column 22, for example to the feed 40 or reflux 50.
• this water reacts with methyl acetate and/or methyl iodide in column 22 to form methanol, which is then dehydrated in the presence of an acid catalyst (such as HI) to form DME.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Crystallography & Structural Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Priority Applications (11)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34911125

Family Applications (1)

Country Status (20)

Cited By (8)

Families Citing this family (75)

Citations (4)

Family Cites Families (20)

• 2004
  • 2004-03-02 US US10/708,420 patent/US7223886B2/en not_active Expired - Lifetime
• 2005
  • 2005-02-24 UA UAA200609403A patent/UA84906C2/ru unknown
  • 2005-02-24 KR KR1020127011247A patent/KR101233605B1/ko not_active Expired - Lifetime
  • 2005-02-24 CA CA2556998A patent/CA2556998C/en not_active Expired - Fee Related
  • 2005-02-24 BR BRPI0508438A patent/BRPI0508438B1/pt active IP Right Grant
  • 2005-02-24 JP JP2007501855A patent/JP2007526310A/ja active Pending
  • 2005-02-24 EP EP05723799.2A patent/EP1720821B1/en not_active Expired - Lifetime
  • 2005-02-24 ES ES18210232T patent/ES2859449T3/es not_active Expired - Lifetime
  • 2005-02-24 WO PCT/US2005/006092 patent/WO2005085166A1/en not_active Ceased
  • 2005-02-24 EP EP18210232.7A patent/EP3486228B1/en not_active Expired - Lifetime
  • 2005-02-24 RS RSP-2006/0494A patent/RS20060494A/sr unknown
  • 2005-02-24 PL PL381109A patent/PL209551B1/pl not_active IP Right Cessation
  • 2005-02-24 CN CNB2005800069275A patent/CN100522916C/zh not_active Expired - Lifetime
  • 2005-02-24 ZA ZA200607203A patent/ZA200607203B/en unknown
  • 2005-02-24 NZ NZ549260A patent/NZ549260A/en not_active IP Right Cessation
  • 2005-02-24 AU AU2005219834A patent/AU2005219834B2/en not_active Ceased
  • 2005-02-24 RU RU2006134649/04A patent/RU2372321C2/ru active
  • 2005-02-24 ES ES05723799T patent/ES2714170T3/es not_active Expired - Lifetime
  • 2005-02-24 KR KR1020067017672A patent/KR20060129428A/ko not_active Ceased
  • 2005-02-28 MY MYPI20085092A patent/MY148351A/en unknown
  • 2005-02-28 MY MYPI20050821A patent/MY139400A/en unknown
  • 2005-03-01 AR ARP050100763A patent/AR048247A1/es not_active Application Discontinuation
  • 2005-03-02 TW TW094106279A patent/TWI433834B/zh not_active IP Right Cessation
  • 2005-03-02 TW TW100137114A patent/TWI549939B/zh not_active IP Right Cessation
• 2006
  • 2006-09-29 NO NO20064430A patent/NO20064430L/no not_active Application Discontinuation
• 2007
  • 2007-04-20 US US11/788,455 patent/US8076507B2/en active Active
• 2012
  • 2012-12-03 JP JP2012264371A patent/JP2013082715A/ja active Pending
• 2015
  • 2015-08-10 JP JP2015158385A patent/JP6506657B2/ja not_active Expired - Lifetime
• 2017
  • 2017-08-15 JP JP2017156962A patent/JP6465934B2/ja not_active Expired - Lifetime

Patent Citations (4)

Non-Patent Citations (3)

Also Published As

Similar Documents

Legal Events