KR102493740B1 - Method for producing acetic acid - Google Patents

Abstract

The present invention relates to a carbonylation process for producing acetic acid comprising separating a vapor product stream from a carbonylation reactor to produce a crude acid product comprising acetic acid comprising lithium cations; contacting the crude acetic acid product with a cation exchanger in acid form in a first treatment unit to produce an intermediate acid product; and contacting the intermediate acetic acid product with a metal-exchanged ion exchange resin having acid cation exchange sites in a second processing unit to produce purified acetic acid. Embodiments relating to operation of a processing device that includes a plurality of sampling ports are also disclosed.

Description

Method for producing acetic acid

The present invention relates to a method for producing acetic acid.

related application

This application claims priority to U.S. Provisional Application No. 62/109765, filed on January 30, 2015, and also claims priority to U.S. Provisional Application No. 62/141490, filed on April 1, 2015. U.S. Application Serial No. 14/694913, filed on the 23rd, claims priority, each of which is incorporated herein by reference in its entirety.

Acetic acid production by carbonylation involves continuously reacting methanol and carbon monoxide in a reactor in the presence of a catalyst. The reaction mixture present in the reactor comprises a transition metal, which may be a Group 9 metal, which may be iridium and/or rhodium, and may further include one or more solvents, water, various stabilizers, co-catalysts, promoters, and the like. . Reaction mixtures known in the art may include acetic acid, methyl acetate, methyl iodide, hydrogen iodide, a hydrogen iodide promoter, and the like.

A complex network of interdependent equilibria comprising liquid acetic acid reaction components exists within the reactor, including those for the formation of acetic acid as well as the various impurities produced in the reactor. Impurities that may be present in acetic acid include permanganate reducing compounds (PRCs) such as acetaldehyde. Accordingly, acetic acid processes disclosed in the art may further include various purification processes and control schemes in which impurity formation is minimized and/or generated impurities are removed from the process or converted to acetic acid products.

Various impurities present in acetic acid products are difficult to remove. In various aspects of the acetic acid production process, there is a need to control and monitor the purification system.

In an embodiment, the process comprises carbonylating at least one selected from the group consisting of methanol, dimethyl ether, and methyl acetate in the presence of 0.1 to less than 14 weight percent of water, a rhodium catalyst, methyl iodide, and lithium iodide to produce a reaction comprising acetic acid. forming a reaction medium within the reactor; separating the reaction medium into a liquid recycle stream and a vapor product stream; separating the vapor product stream in no more than two distillation columns in a primary purification train to produce a crude acid product comprising acetic acid comprising lithium cations; contacting the crude acetic acid product with a first purification resin comprising a cation exchanger in acid form in a first treatment device to produce an intermediate acid product; contacting the intermediate acetic acid product with a metal-exchanged ion exchange resin having an acid cation exchange site in a second processing unit to produce purified acetic acid, wherein the first processing unit, the second processing unit, or both individually, one or more sampling ports disposed through a side of the processing device; obtaining a liquid sample of the first purifying resin, the second purifying resin, an acetic acid stream present in the processing unit, or a combination thereof through a corresponding sampling port; and determining the concentration of the impurity in the one or more samples.

This summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This disclosure is not intended to identify key or essential features of the claims, nor is it intended to help limit the scope of the claims.

1 is a schematic diagram of a process for producing acetic acid according to one embodiment.
2 is a schematic diagram of a series of processing devices according to one embodiment.
3 is a cross-sectional view of a processing device according to one embodiment.
4 is a cross-sectional view of a sampling device according to one embodiment.
5 is a block diagram illustrating the steps of filling a processing unit column with resin according to an embodiment.

When initially developing any such practical embodiment, a number of implementation-specific decisions must be made to achieve the developer's specific goals, such as complying with system-related and business-related constraints, which are implementation-specific. Each one is different. It will also be appreciated that such a development effort, while complex and time consuming, may nevertheless be a routine undertaking for those skilled in the art having the benefit of the present invention. In addition, the processes disclosed herein may also include components other than those cited or specifically mentioned as will be apparent to one of minimal skill in the art.

In the Summary and Detailed Description, each numerical value is to be read once as modified by the term "about" (unless expressly modified yet) and left unmodified unless the context dictates otherwise. need to read it again Also, in the Summary and Detailed Description, concentration ranges listed or described as useful or suitable, etc., should be understood as indicating any and all concentrations within the range, inclusive of the endpoints. For example, “a range of 1 to 10” should be read as representing each and every possible number along the continuum of about 1 to about 10. Accordingly, even if certain data points within the range or even data points within the range are explicitly identified or refer to only a small number of specific data points, the inventors should consider any and all data points within the scope of the present invention to be specified, and the inventors It should be understood that one must possess knowledge of the entire range and all points within that range.

Throughout the entire specification, including the claims, the following terms have the meanings indicated unless otherwise indicated.

As used in the specification and claims, “near” includes “next to”. The term "and/or" refers to both the inclusive instance of "and" and the exclusive instance of "or" and is used herein for brevity. For example, a mixture comprising acetic acid and/or methyl acetate may include acetic acid alone, methyl acetate alone, or both acetic acid and methyl acetate.

As used herein, symbols representing elements and new numbering schemes for groups of the periodic table are used consistent with those described in Chemical and Engineering News, 63 (5), 27 (1985). All molecular weights are weight averages unless otherwise specified.

All percentages are expressed as weight percent (wt%) based on the total weight of the particular composition or stream present, unless otherwise stated. Unless otherwise stated, room temperature is 25° C. and atmospheric pressure is 101.325 kPa.

For purposes herein, the percentage of exchanged active sites of a resin is based on the total exchange capacity in milliequivalents per gram (meq/g). For example, in a cationic ion exchange resin having a cation exchange capacity of 2 meq/g, substitution by silver ions of 2 meq/g constitutes substitution of 100% of the active sites with silver, and 1 meq/g A substitution constitutes substitution of 50% of the active site.

For purposes herein:

Acetic acid may be abbreviated as "AcOH";

Methyl acetate may be abbreviated as “MeAc”;

Methyl iodide may be abbreviated as “MeI”;

Carbon monoxide may be abbreviated as "CO".

A permanganate reducing compound (PRC) refers to an oxidizable compound that causes the designation of a failure of the permanganate test, as readily understood by those skilled in the art (see "A New System For Automatic Measurement of Permanganate Time," Laboratory Automation and Information Management, 34, 1999, 57-67). Examples of the permanganate reducing compound (PRC) include acetaldehyde, acetone, methyl ethyl ketone, butyraldehyde, crotonaldehyde, 2-ethyl crotonaldehyde and 2-ethyl butyraldehyde, and the like, and their aldol condensation products.

For purposes herein, "overhead" of a distillation column refers to the minimum boiling condensable fraction at or near the top of the distillation column. Similarly, the retentate of the distillation column represents the highest boiling fraction coming from or near the bottom of the distillation column. It is understood that the residue may be taken, for example, from just above the bottom exit of the distillation column, where the bottom of the column is, as will be readily appreciated by those skilled in the art, unusable tar, solid waste or minimal it's a stream Similarly, an overhead stream can be taken, for example, just below the top exit of a distillation column, where the lowest boiling fraction is a non-condensable stream or a minimal stream, as will be readily appreciated by those skilled in the art. indicate

As used herein, average residence time of a column feed stream in a column, unless otherwise specified, refers to the total flow rate provided to the column divided by the total unoccupied volume present in the column.

For purposes herein, a processing vessel, which may be referred to as a column, has an inlet and an outlet. The interior of the column, referred to herein as the inner chamber, is suitable for filling with purification resin. The terms processing unit and column are used interchangeably herein unless otherwise specified. For purposes herein, treatment equipment and columns other than distillation columns are used interchangeably.

Mass flow rate, as used herein, refers to kg/hr unless otherwise stated, and can be determined directly or calculated from volumetric measurements. If the total mass flow rate or concentration of a component is accepted as being present "if present", then that component may or may not be present in the stream beyond the detection limits of the appropriate analytical method, as readily understood by those skilled in the art. It should be understood that it may be

As used herein, when the mass flow rate of a stream is “controlled” to a specific flow rate or to a rate that is proportional to the mass flow rate of another stream, such control is directly related to a specific process stream stream, as will be readily appreciated by those skilled in the art. , or controlling the mass flow of a particular stream by changing a stream that directly affects the mass flow rate of a desired stream. All such ratios are expressed as mass to mass weight percent unless otherwise stated.

As used herein, a carbonylatable reactant is any substance that reacts with carbon monoxide under reaction conditions to produce acetic acid or the desired product. Reactants capable of carbonylation include methanol, methyl acetate, dimethyl ether, methyl formate, and the like.

As used herein, a low moisture carbonylation process is defined as having a finite concentration of water in the carbonylation reactor of about 14% by weight or less.

As used herein, when at least a portion of a stream is recycled or redirected to another portion of the process, "portion" is to be understood as referring to a portion of the total mass flow of the stream. A stream may be combined with another stream (ie indirectly recycled), but all components originally present in the stream are present after being combined.

In contrast, a stream "derived" from another stream may contain the entire stream, or may contain less than all individual components initially present in the stream. Thus, a stream "derived" from a particular stream may include a stream that has undergone further processing or purification prior to disposal. For example, a stream distilled before being recycled is derived from the original stream.

As used herein, unless otherwise specified, a limitation based on a comparison between an effect observed in the presence of an ingredient to an effect observed in the absence of the same ingredient is essentially excluding the presence or absence of the identified ingredient. Comparisons made under identical conditions (e.g., essentially the same composition, essentially the same temperature, time, and other conditions).

Impurities present in acetic acid include various iodine-containing species. Examples include alkyl iodides having from 1 to about 20 carbon atoms. High molecular weight alkyl iodides with greater than about 6 carbons may be present at parts per billion (ppb) levels in the final product. These impurities are problematic for many end uses of acetic acid and must be removed according to various purity standards. Other impurities include various aldehydes and corrosive metals. These contaminants can be removed by contacting acetic acid with a suitable purification resin at a temperature above about 50° C. (see US6657078). However, the use of these purification resins requires monitoring of the final product and the resin itself to prevent impurities from "breaking" the purification resin bed during manufacture.

Samples of the final product are readily available, but samples of the purification resin used in the purification process are rarely obtained while the purification system is running. Additionally, shutdown of such purification systems to obtain resin samples is uneconomical and often questionable. However, sampling devices according to one or more embodiments of the present invention allow both liquid samples and samples of solid purified resin to be collected and analyzed at various points along a bed of resin. The ability to obtain such samples enhances monitoring and control of the process. These sample ports can also predict when the resin will drain before there are excessive amounts of impurities present in the final product.

In an embodiment, the method comprises providing a column comprising an inner chamber containing an active purification resin positioned between a column inlet and a column outlet, wherein the column includes one disposed between the column inlet and the column outlet. further comprising one or more sample ports, wherein the one or more sample ports include a liquid sample port, a solid sample port, or both; and flowing an acetic acid stream having a first concentration of impurities, if present, through the column at a temperature and flow rate sufficient to produce a purified acetic acid stream at the column outlet having a second concentration of impurities less than the first concentration. It includes steps to Thus, acetic acid is contacted with the purification resin in the column to remove impurities and purify the acetic acid. In an embodiment, the method further comprises opening one or more sample ports prior to or simultaneously with flowing an acetic acid stream through the column. In an embodiment, the impurity includes iodine, chromium, nickel, iron, or combinations thereof. In an embodiment, the iodide can be an alkyl iodide. In an embodiment, the purification resin comprises a macroreticular, strong acid ion exchange resin having at least about 1% active sites in the form of silver or mercury and/or has a temperature of at least about 50°C.

In an embodiment, opening one or more sample ports comprises obtaining a sample of the purification resin through one or more solid sample ports, and a liquid sample of the acetic acid stream present in the column through one or more liquid sample ports. comprising, or a combination thereof, the method further comprising determining the concentration of the impurity in one or more samples.

In embodiments, the concentration of one or more impurities is determined using gas chromatography, high pressure liquid chromatography, atomic absorption, inductively coupled plasma spectroscopy, mass spectroscopy, x-ray fluorescence spectroscopy, or a combination thereof.

In an embodiment, the impurity concentration of the one or more samples is compared to a predetermined impurity concentration value and determines whether the impurity concentration represents consumption of purification resin at a point within the column corresponding to the location of the sample port from which the sample was obtained. In an embodiment, the method may further comprise stopping the flow of acetic acid through the column. In an embodiment, the flow of acetic acid is stopped before essentially all of the active purification resin present in the column is consumed such that the impurity concentration in the product acetic acid does not result in acetic acid unsuitable for the particular end use.

In an embodiment, a second column similar to the first can be provided, wherein the acetic acid is flowed through and purified while the flow through the first column is stopped.

In an embodiment, while flow is stopped over the column, at least a portion of the spent resin is regenerated to produce a purified acetic acid stream prior to resuming flow of the acetic acid stream through the column. In an embodiment, regeneration of the spent resin comprises removing at least a portion of the spent resin from the column and refilling at least a portion of the column with an active purification resin. In an embodiment, at least a portion of the active resin used to recharge the column comprises previously spent resin that has been regenerated to active purification resin. In an embodiment, at least a portion of the spent resin is regenerated within the column as an active purification resin.

In an embodiment, the method comprises the following steps: (a) comprising an inner chamber bounded by a plurality of sides disposed radially about a central axis, through which the inner chamber is in fluid communication with the outlet end and is in longitudinal direction; providing a column having a separate inlet end; (b) introducing a sufficient amount of purifying resin into the inner chamber to fill a portion of the inner chamber; (c) flowing an aqueous wash solution from the outlet end through the interior chamber to the inlet end at a flow rate and for a time sufficient to wash and/or remove particulates from the purification resin; and (d) said column at a temperature and flow rate sufficient to produce an acetic acid stream having a first concentration of impurities and, if present, a purified acetic acid stream having a second concentration of impurities lower than the first concentration. It includes the step of flowing through.

In an embodiment, the column comprises one or more sample ports disposed between the column inlet and the column outlet, wherein the one or more sample ports comprise a liquid sample port, a solid sample port, or both, wherein the method further comprising opening one or more sample ports. In an embodiment, the aqueous wash is run for at least 60 minutes.

In an embodiment, after step (c) of flowing an aqueous wash liquid through the column, an amount of inert gas is directed to the column inlet to remove a portion of the wash liquid. In an embodiment, a countercurrent flow of acetic acid (from outlet to inlet) may flow through the column at a flow rate and for a time sufficient to remove essentially all vapor from the inner chamber. In an embodiment, removing the vapor may include opening the one or more sample ports. In an embodiment, the countercurrent flow rate of acetic acid is about 0.05 bed volume/minute or less, and the time is about 30 minutes or less.

In an embodiment, the purification resin provides fluid communication between an inner chamber and a lower outlet of a vessel containing a slurry comprising the purification resin, and then pneumatically pneumatically pneumatically pneumatically at least a portion of the slurry from the vessel into the interior chamber. It is pneumatically induced into the inner chamber of the column by applying a pressure to the headspace of the vessel in an amount sufficient to transfer to the column.

In an embodiment, an internal chamber of the column and/or the vessel is used to deoxygenate the headspace prior to filling the column with the purification resin (i.e., such that the space contains less than 1% oxygen by weight). The headspace is purged with an inert gas such as nitrogen.

In an embodiment, the process comprises carbonylating at least one selected from the group consisting of methanol, dimethyl ether, and methyl acetate in the presence of 0.1 to less than 14 weight percent of water, a rhodium catalyst, methyl iodide, and lithium iodide to produce a reaction comprising acetic acid. forming a reaction medium within the reactor; separating the reaction medium into a liquid recycle stream and a vapor product stream; separating the vapor product stream in no more than two distillation columns in a first purification train to produce a crude acid product comprising acetic acid comprising lithium cations; contacting the crude acetic acid product with a first purification resin comprising a cation exchanger in acid form in a first treatment device to produce an intermediate acid product; contacting the intermediate acetic acid product with a metal-exchanged ion exchange resin having an acid cation exchange site in a second processing unit to produce purified acetic acid, wherein the first processing unit, the second processing unit, or both individually, one or more sampling ports disposed through a side of the processing device; obtaining a liquid sample of the first purifying resin, the second purifying resin, an acetic acid stream present in the processing unit, or a combination thereof through a corresponding sampling port; and determining the concentration of the impurity in the one or more samples.

In embodiments, the method comprises comparing the impurity concentration of one or more samples to a predetermined impurity concentration value, and the purification at a point within a processing device at which the impurity concentration of the sample corresponds to a location of a sample port from which the sample was obtained. and further comprising determining whether or not the resin is depleted. In an embodiment, the method comprises stopping the flow of acetic acid through the processing device before essentially all of the active purification resin present in the processing device is consumed, regenerating at least a portion of the spent resin, and and resuming flow of the acetic acid stream through the processing device to produce the purified acetic acid stream.

In an embodiment, the metal-exchanged ion exchange resin comprises at least 1% strong acid exchange sites incorporating silver. In an embodiment, the crude acid product comprises 10 ppm or less of lithium.

In an embodiment, separating the vapor product stream comprises distilling the vapor product stream in a first distillation column and taking a sideraw to produce a distilled acetic acid product; and distilling the distilled acetic acid product in a second distillation column to produce a crude acid product including acetic acid and lithium cations. In an embodiment, the method further comprises adding a potassium salt selected from the group consisting of potassium acetate, potassium carbonate and potassium hydroxide to the distilled acetic acid product prior to distilling the distilled acetic acid product in a second distillation column. do; Here, at least a portion of the potassium is removed by a cation exchanger in acid form.

In an embodiment, the crude acetic acid product is contacted with a cation exchanger at a temperature of 50°C to 120°C. In an embodiment, the intermediate acetic acid product is contacted with a metal-exchanged ion exchange resin at a temperature of 50° C. to 85° C.; or combinations thereof. In an embodiment, the intermediate acetic acid product has a lithium ion concentration of less than 50 ppb.

In an embodiment, the cation exchanger in acid form comprises a resin of strong acid cation exchange macroreticular, macroporous or mesoporous resin in acid form. In an embodiment, the method further comprises treating the purified acetic acid product with a cation exchange resin to recover any silver, mercury, palladium or rhodium. In an embodiment, the water concentration in the reaction medium is controlled between 0.1 and 5 weights based on the total amount of reaction medium present.

In an embodiment, the method introduces a lithium compound selected from the group consisting of lithium acetate, lithium carboxylate, lithium carbonate, lithium hydroxide, and mixtures thereof into the reactor to increase the concentration of lithium acetate in the reaction medium from 0.3 to 0.7 weight by weight. It further includes the step of maintaining. In an embodiment, the method comprises maintaining a hydrogen iodide concentration in the reaction medium between 0.1 and 1.3 by weight; maintaining a rhodium catalyst concentration in the reaction medium between 300 and 3000 wppm; maintaining a water concentration in the reaction medium between 0.1 and 4.1 by weight; maintaining a methyl acetate concentration in the reaction medium between 0.6 and 4.1 by weight; or combinations thereof.

In an embodiment, the method further comprises controlling the butyl acetate concentration in the acetic acid product to 10 wppm or less without directly removing the butyl acetate from the acetic acid product. In an embodiment, the butyl acetate concentration maintains the acetaldehyde concentration in the reaction medium below 1500 ppm; adjust the temperature of the reactor to 150 to 250°C; adjusting the hydrogen partial pressure in the reactor to 0.3 to 2 atm; adjusting the rhodium catalyst concentration in the reaction medium to 100 to 3000 wppm; or by combining them.

In an embodiment, the method further comprises controlling the ethyl iodide concentration in the reaction medium to 750 wppm or less. In an embodiment, the propionic acid concentration in the product acetic acid is less than 250 wppm without direct removal of propionic acid from the product acetic acid, wherein ethyl iodide in the reaction medium and propionic acid in the acetic acid product are in a weight ratio of 3:1 to 1:2 wherein acetaldehyde and ethyl iodide are present in a weight ratio of 2:1 to 20:1 in the reaction medium; At this time, the ethanol concentration in the methanol supplied into the reactor is less than 150 wppm; or a combination thereof. In an embodiment, the ethyl iodide concentration in the reaction medium is controlled by adjusting at least one of the hydrogen partial pressure in the carbonylation reactor, the methyl acetate concentration in the reaction medium, and the methyl iodide concentration in the reaction medium.

acetic acid manufacturing system

The process for producing acetic acid via methanol carbonylation can conveniently be divided into three main areas: reaction systems and processes, light fraction recovery/acetic acid product separation systems and processes, and acetic acid product purification systems and processes. A suitable acetic acid process for the purpose of this application, which produces vapors from a carbonylation reactor that is subsequently distilled in a light ends column to obtain an acetic acid product as a sidedraw, includes a refinery stream, a recycle stream, the type and number of distillation columns used, the use Systems and processes may vary, including various purification processes that have been developed. Examples of suitable processes include US3769329; US3772156; US4039395; US4255591; US4615806; US5001259; US5026908; US5144068; US5237097; US5334755; US5653853; US5683492; US5831120, US5227520; US5416237, US5731252; US5916422; US6143930; US6225498, US6255527; US6339171; US6657078; US7208624; US7223883; US7223886; US7271293; US7476761; US783871; US7855306; US8076507; US20060247466; US20090259072; US20110288333; US20120090981; US20120078012; US2012081418; US2013261334; US2013281735; EP0161874; W09822420; WO0216297; including those described in WO2013137236 and the like, the entire disclosures of which are incorporated herein by reference. A process for the production of acetic acid according to an embodiment disclosed herein, generally indicated as process 100, is schematically illustrated in FIG. 1 .

A low-moisture and low-energy process for the production of acetic acid by carbonylation of methanol has been developed, which uses a rhodium-catalyzed system that operates at less than 14 wt% water and can utilize up to two distillation columns in a primary purification train. include A primary purification train is directed to remove bulk components such as water, methyl acetate, methyl iodide and hydrogen iodide from the vapor product stream from the reactor/flash unit to obtain acetic acid. This primary purification train receives most of the vapor flow from the reactor to obtain acetic acid as the final product. For example, the columns of the first purification train include a light ends column and a drying column. This primary purification train can exclude columns whose main function is to remove key components such as acetaldehyde, alkanes and propionic acid.

The process of making acetic acid can produce cations that collect in the crude acid product. These residual cations can be difficult to remove and can reversely displace iodide in the final metal-exchange guard layer. Thus, the final product may contain unacceptable levels of iodide despite the use of a metal exchange guard layer. The present invention provides a method for removing cations.

Sources of cations can come from various promoters, co-catalysts, additives, in situ reactions, and the like. For example, a low moisture and low energy process involves the use of a promoter such as lithium iodide, which can be formed in situ after adding lithium acetate or other compatible lithium salt to the reaction mixture. Thus, the process stream may contain some amount of lithium ions. Also, since the process uses a maximum of two distillation columns in the first purification train and preferably the first purification does not include a column to remove the heavies, the crude acid product will contain larger alkyl iodide compounds. eg C ₁₀ -C ₁₄ alkyl iodide as well as cations such as lithium. Sometimes more than 10% or even more than 50% of the iodides present have an organic chain length of more than 10 carbon atoms. Thus, greater than 10 ppb may be greater than 20 ppb, greater than 50 ppb, greater than 100 ppb or greater than 1 ppm C ₁₀ -C ₁₄ alkyl iodide. These higher alkyl iodides may be present in addition to the more common shorter chain length iodide impurities found in crude acid products of iodide catalyzed carbonylation processes, including methyl iodide, HI and hexyl iodide. Common iodide impurities are typically removed from the crude acid product using metal-exchanged strong acid ion exchange resins where the metal is, for example, silver or mercury. However, it has been found that the silver or mercury in metal-exchanged strong acid ion exchange resins can be replaced by residual lithium, resulting in lower resin capacity and efficiency and potential product contamination with silver or mercury.

The cations in the crude acid product may result from the use of organic alkali salt ligands, such as organolithium salt ligands as described in CN101053841 and CN1349855, the entire contents and disclosures of which are incorporated herein by reference. CN101053841 describes ligands comprising lithium acetate or lithium oxalate. CN1349855 describes bimetallic catalysts with metal lithium organic ligands coordinating cis-dicarbonyl rhodium structures. The metal lithium organic ligand is a pyridine derivative such as lithium pyridine-2-formate, lithium pyridine-3-formate, lithium pyridine-4-formate, lithium pyridine-3-acetate, lithium pyridine-4-acetate or lithium pyridine. -3-propionate. Indeed, it is believed that the lithium salt component of all these ligands generates lithium iodide in situ in the reaction medium after exposure to methyl iodide at the reaction temperature and pressure in the carbonylation reactor. At least some small amount of the lithium component will be entrained in the purification system. Thus, purification systems according to the present invention can also remove lithium formed in situ from the use of these types of organic ligands.

Cations may also be present as a result of the use of non-lithium salts, such as through the use of bimetallic Rh chelating catalysts with amine functionality, such as those described in CN1640543, the entire contents and disclosure of which are incorporated herein by reference. do. According to CN 16040543, cationic species contain N and O donor atoms and are formed from aminobenzoic acids. The amine can be quaternized to methyl iodide in situ in the reaction medium at the reaction temperature and pressure to form a quaternary nitrogen cation. Quaternary nitrogen cations similar to lithium cations can be transported through the crude acid product and can be removed using the present invention prior to the metal-exchange guard layer.

Embodiments include a low moisture and low energy process for producing acetic acid by carbonylation of methanol, dimethyl ether and/or methyl acetate in the presence of 0.1 to less than 14 weight percent water, a metal catalyst, methyl iodide and lithium iodide. do. In an embodiment, the low-energy process uses no more than two distillation columns (e.g., a water removal or dehydration column and a light ends column that does not use a third heavy ends column) in a first-grade purification train, and produces After the acidic acid product is purified with an acid form cation exchanger to remove residual lithium ions, a metal-exchanged ion having an acid cation exchange site comprising at least one metal selected from the group consisting of silver, mercury, palladium and rhodium is obtained. treated with an exchange resin. Metal-exchanged ion exchange resins contain at least 1% of strong acid exchange sites filled with silver, mercury, palladium and/or rhodium, for example at least 1% silver, mercury, palladium and/or rhodium, at least 5% silver, mercury, palladium and/or rhodium. /or rhodium, greater than 10% silver, mercury, palladium and/or rhodium, or greater than 20% silver, mercury, palladium and/or rhodium. Replacement of silver, mercury, palladium and/or rhodium from metal-exchanging sites by lithium is achieved in the first purification train by removing lithium using a cation exchanger prior to using a resin with metal-exchanging strong acid cation sites. It is reduced or eliminated in the case of processes using two or less distillation columns. In an embodiment, a purification system other than the primary purification train may use a distillation column to remove impurities from reactor components, such as an aldehyde removal system, wherein acetaldehyde and other PRCs are removed from the methyl iodide phase followed by Methyl iodide is returned to the reaction medium.

A particularly preferred process is one in which lithium is removed using a cation exchanger followed by iodide removal using a silver-exchanged cation substrate. The crude acid product contains organic iodides with aliphatic chain lengths greater than C ₁₀ which in many cases need to be removed. Sometimes more than 10% eg more than 30% or even more than 50% of the iodides present have an organic chain length of more than 10 carbon atoms.

Decyl iodide and dodecyl iodide are particularly prevalent in heavy fractions and in the absence of other finishing equipment and are difficult to remove from the product. The silver-exchanged cationic substrates of the present invention typically remove more than 90% of this iodide; Often the crude acid product has a total of 10 to 1000 ppb of iodide prior to treatment, rendering the product unusable for iodide sensitive applications.

Iodide levels of 20 ppb to 1.5 ppm are typical in the crude acid product prior to iodide removal treatment; On the other hand, the iodide removal treatment preferably acts to remove at least about 95% of the total iodide present. In a typical embodiment, the lithium/iodide removal treatment involves contacting the crude acid product with a cation exchanger to remove at least 95% of the lithium ions, and then subjecting the crude acid product to silver-exchanged sulfonic acid functionalized macroreticular ion exchange contacting with a resin, wherein the product has an organic iodide content of greater than 100 ppb prior to treatment and an organic iodide content of less than 10 ppb after contacting with the resin.

Lithium has also been found to be incorporated into the crude acid product in the absence of heavy content and other finishing devices. Even low levels of lithium, as low as 10 ppb in the crude acid product can cause iodide removal problems. 10 ppm or less, e.g., 5 ppm or less, 1 ppm or less, 500 ppb or less, 300 ppb or less, or 100 ppb or less of lithium by weight of the crude acid product, in the drying column of the acetic acid process, such as the last column of the first purification train. It may be present in the acid-containing crude acid product exiting. Regarding the range, 0.01 ppm to 10 ppm lithium may be present in the crude acid product, for example, 0.05 ppm to 5 ppm or 0.05 ppm to 1 ppm. A significant amount of lithium can be removed by using a cation exchanger in acid form prior to introducing the crude acid product to the metal-exchanged resin. More than 90% by weight of the stream, for example 95% or 99% by weight of lithium, can be removed by the cation exchanger. Thus, the stream exiting the acid-form cation exchanger may contain less than 50 ppb lithium, such as less than 10 ppb or less than 5 ppb lithium. Removal of this lithium can greatly extend the life of the metal-exchanged resin.

Reaction system and process

As shown in FIG. 1, the process for producing acetic acid 100 involves the removal of a portion of the reaction medium continuously via line 113 and a separation system, such as a flash unit 112 (which removes acetic acid and other volatile components). and a carbonylation reactor (104) that is separated from the reaction medium and subjected to flash or low pressure distillation (used to recycle non-volatile components to the reaction medium via stream (110)). The volatile components of the reaction medium are then passed overhead via line 122 to the light ends recovery/acetic acid product separation system and process beginning with light ends column 124.

As shown in FIG. 1, methanol-containing feed stream 101 and carbon monoxide-containing feed stream 102 are directed to a liquid phase reaction medium of carbonylation reactor 104, where the carbonylation reaction involves a catalyst, water , methyl iodide, methyl acetate, acetic acid, iodine salts, HI, and other reaction medium components.

In an embodiment, the carbonylation reactor 104 may be a stirred vessel, a bubble-column type vessel, or a combination thereof, wherein the reaction liquid or slurry contents are maintained at the same level as in normal operation. In an embodiment, carbon monoxide may be continuously introduced into the reaction medium of the carbonylation reactor, including an agitator used to agitate the contents. The gaseous feed is preferably completely dispersed through the reaction liquid by means of such agitation. In an embodiment, the reactor system includes multiple recycle lines (where various components are recycled to the reaction medium from other parts of the process) and various vapor purge lines through which additional processing and the like may be performed. All vents and other vapor purge lines are connected to one or more scrubber systems 139, as will be readily appreciated by those skilled in the art, and all condensable components are finally recycled to the carbonylation reactor before the vapor stream is exhausted to atmosphere. should be understood as being

In an embodiment, gaseous purge stream 106 may be consumed from reactor 104 to scrubber system 139 to prevent buildup of gaseous byproducts and to control carbon monoxide partial pressure and/or total reactor pressure. The reactor system may further include a loop around the pump 103 for controlling the temperature of the reactor.

In an embodiment, the reaction medium comprises a metal catalyst or a Group 9 metal catalyst, or a catalyst comprising rhodium and/or iridium. In an embodiment, the reaction medium includes a rhodium catalyst.

In an embodiment, the rhodium component of the catalyst system is in the form of a coordinating compound with rhodium and is believed to be present with a halogen component providing one or more of the ligands of the coordinating compound. In addition to the coordination of rhodium with halogen, carbon monoxide is thought to coordinate with rhodium. In an embodiment, the rhodium component of the catalyst system is a rhodium metal in the reaction zone, in the form of rhodium salts such as oxides, acetates, iodides, carbonates, hydroxides, chlorides, etc., or materials that result in the formation of coordination compounds of rhodium in the reaction environment. It can be provided by introducing rhodium in compound form. In an alternative embodiment, the carbonylation catalyst comprises rhodium dispersed in a liquid reaction medium or supported on an inert solid phase. Rhodium can be introduced into a reaction system in a variety of forms, and the exact nature of the rhodium moiety within the active catalyst complex can be uncertain.

In an embodiment, the catalyst concentration is maintained in the reactor in an amount of about 200 to about 5000 ppm based on the total weight of the reaction medium.

In an embodiment, the reaction medium may further include a halogen-containing catalyst promoter. Suitable examples include organic halides, alkyl, aryl and substituted alkyl or aryl halides. In an embodiment, the halogen-containing catalyst promoter is in the form of an alkyl halide corresponding to the alkyl radical of the feed alcohol in which the alkyl radical is carbonylated. Thus, in the carbonylation of methanol to acetic acid, the halide promoter will include methyl halide or methyl iodide (MeI). In an embodiment, the reaction medium comprises at least about 5 weight percent MeI, based on the total weight of the reaction medium. In an embodiment, the reaction medium comprises at least about 5% by weight and up to about 50% by weight of MeI. In an embodiment, the reaction medium comprises at least about 7 wt% or at least about 10 wt% MeI and at most about 30 wt% or at most about 20 wt% MeI, based on the total weight of the reaction medium.

In an embodiment, the liquid reaction medium used may include any solvent compatible with the catalyst system, and may include pure alcohol or mixtures of alcohol feedstock and/or product carboxylic acids and/or esters of the two compounds. can In an embodiment, the solvent used for the liquid reaction medium comprises acetic acid (AcOH). In an embodiment, the reaction medium comprises at least about 50% AcOH by weight. In an embodiment, the reaction medium comprises at least about 50% and up to about 90% AcOH by weight. In an embodiment, the reaction medium comprises at least about 50% or at least about 60% by weight of AcOH and at most about 80% or at most about 70% by weight of AcOH, based on the total weight of the reaction medium.

In an embodiment, the reaction medium includes at least a finite concentration of water. In an embodiment, the reaction medium includes a detectable amount of water. In an embodiment, the reaction medium comprises at least about 0.001 weight percent water. In an embodiment, the reaction medium comprises at least about 0.001 weight percent and up to about 14 weight percent water. In an embodiment, the reaction medium comprises at least about 0.05%, or at least 0.1%, or at least 0.5%, or at least 1%, or at least 4% water, and up to about 10% or 5% water, based on the total weight of the reaction medium. % or less of water.

In an embodiment, the reaction medium further comprises an ester of an alcohol and a carboxylic acid product used for carbonylation. In an embodiment, the reaction medium comprises methyl acetate. In an embodiment, the reaction medium comprises at least about 0.5 weight percent methyl acetate (MeAc). In an embodiment, the reaction medium comprises at least about 1 weight percent and up to about 50 weight percent MeAc. In an embodiment, the reaction medium comprises at least about 1.5%, or at least about 2%, or at least about 3% MeAc, and at most about 20%, or at most about 10% MeAc, based on the total weight of the reaction medium. .

In an embodiment, the reaction medium further comprises additional iodide ions beyond the iodide ions present as hydrogen iodide. In an embodiment, the iodide ion concentration is provided by an iodide salt or lithium iodide (LiI). In an embodiment, the reaction medium is maintained under a low moisture concentration where methyl acetate and lithium iodide are present in concentrations sufficient to act as rate accelerators (see US 5001259).

In embodiments, at least a portion of the iodide ion concentration in the reaction medium results from metal iodide salts, or iodide salts of organic cations, or cations based on quaternary amines, phosphines, and the like. In an embodiment, the iodide is a metal salt, Group 1 or Group 2 iodide salt. In an embodiment, the reaction medium comprises alkali metal iodide or lithium iodide. In an embodiment, the iodide concentration is greater than or equal to iodide ions present as hydrogen iodide. In an embodiment, the reaction medium includes an iodide salt or lithium iodide in an amount sufficient to produce a total iodide ion concentration greater than about 2% by weight. In an embodiment, the reaction medium contains an iodide salt or lithium iodide in an amount sufficient to produce a total iodide ion concentration of greater than about 2% and less than or equal to about 40% by weight, based on the total weight of the reaction medium. include In an embodiment, the reaction medium comprises at least about 5%, or at least about 10%, or at least about 15% by weight of iodide ions and at most about 30% or less than about 20% by weight, based on the total weight of the reaction medium. contains the odide ion.

In an embodiment, the reaction medium may further comprise hydrogen as determined by the partial pressure of hydrogen present in the reactor. In an embodiment, the hydrogen partial pressure in the reactor is greater than or equal to about 0.1 psia (0.7 kPa) or 0.5 psia (3.5 kPa) or 1 psia (6.9 kPa) and less than or equal to about 150 psia (1.03 MPa) or less than or equal to 100 psia (689 kPa) or 345 Less than 50 psia (kPa) or less than 20 psia (138 kPa).

In an embodiment, the reactor temperature, ie, the temperature of the reaction medium, is at least about 150°C. In an embodiment, the reactor temperature is greater than or equal to about 150°C and less than or equal to about 250°C. In an embodiment, the reactor temperature is greater than or equal to about 180°C and less than or equal to about 220°C.

In an embodiment, the carbon monoxide partial pressure in the reactor is at least about 200 kPa. In an embodiment, the CO partial pressure is greater than about 200 kPa and less than or equal to about 3 MPa. In an embodiment, the CO partial pressure in the reactor is at least about 300 kPa or at least 400 kPa or at least 500 kPa and is at most about 2 Mpa or at most 1 Mpa. The total reactor pressure represents the combined partial pressure of all reactants, products and by-products present therein. In an embodiment, the total reactor pressure is greater than or equal to about 1 MPa and less than or equal to about 4 MPa.

In an embodiment, the liquid reaction medium is consumed from carbonylation reactor 104 and directed to flash device 112 having a pressure lower than that present in the reactor at a rate sufficient to maintain a constant level between its top and bottom. is introduced into the flash device 112 at the midpoint of In the flash unit, the less volatile components, i.e. the catalyst solution, exit as base stream 110 (mainly acetic acid containing rhodium and iodide salts with small amounts of methyl acetate, methyl iodide, acetic acid and water). and recycled to the reaction medium. The overhead 122 of the flash unit contains the product acetic acid, primarily with methyl iodide, methyl acetate, water and PRC. Some of the carbon monoxide may be emitted to the top of the flash unit along with gaseous by-products such as methane, hydrogen, carbon dioxide, and the like.

Light content recovery/acetic acid product separation system and process

In an embodiment, the overhead stream from flash unit 112 is sent as stream 122 to a light ends column 124, referred to in the art as a stripper column, where distillation is performed herein as a first over A low boiling overhead vapor stream 126, referred to as head stream 126, and a purified acetic acid product stream 128 (which in the embodiment is removed as a side stream) are provided. Light ends column 124 further produces a high boiling residue stream 116 that can be subjected to further purification and/or recycled into the reaction medium.

In an embodiment, the first overheads 126 are condensed and then directed to an overhead phase separation unit 134, referred to herein as an overhead decanter. In an embodiment, first overhead 126 includes methyl iodide, methyl acetate, acetic acid, water and one or more PRCs. In an embodiment, the condensed first overhead stream 126 is a light aqueous phase 135 comprising water, acetic acid, methyl iodide, methyl acetate and one or more permanganate reducing compounds (PRCs) such as acetaldehyde. ); and a heavy phase 137 comprising methyl iodide, methyl acetate, which may include one or more PRCs.

In an embodiment, at least a portion of heavy phase 137, at least a portion of light phase 135, or a combination thereof are returned to the reaction medium via lines 118 and 114, respectively. In an embodiment, a portion of light phase stream 135 may be recycled to the reaction medium in stream 114 to provide water to the reaction medium as needed. In an embodiment, heavy phase 137 is recycled to the reactor via 118.

In an embodiment, light phase 135, heavy phase 137, or a combination thereof is sent via stream 142 to one or more purification processes 108, such as an aldehyde removal system. The subsequently purified stream is then returned to the process via one or more streams collectively referred to as 155.

Although the specific composition of the light liquid phase 135 can vary widely, some exemplary compositions are provided in Table 1 below.

In one embodiment, the overhead decanter 134 is arranged and configured to maintain a low interface level to prevent excessive retention of methyl iodide. The specific composition of heavy liquid phase 137 can vary widely, but some exemplary compositions are provided in Table 2 below.

Although not shown, a portion of the light liquid phase 135 and/or the heavy liquid phase 137 may be separated and directed to an acetaldehyde or PRC removal system to recover methyl iodide and methyl acetate while removing acetaldehyde. there is. As shown in Tables 1 and 2, light liquid phase 135 and/or heavy liquid phase 137 each contain PRC, and the process includes removing carbonyl impurities such as acetaldehyde that degrade the acetic acid product. and may be removed in a suitable impurity removal column and absorber, as described in the following documents: US 6,143,930; 6,339,171; 7,223,883; 7,223,886; 7,855,306; 7,884,237; 8,889,904; and US 2006/0011462 (which are incorporated herein by reference in their entirety). Carbonyl impurities such as acetylaldehyde can react with iodide catalyst promoters to form alkyl iodides such as ethyl iodide, propyl iodide, butyl iodide, pentyl iodide, hexyl iodide, and the like. there is. It is also desirable to remove carbonyl impurities from the light liquid phase, since many of the impurities are due to acetaldehyde.

The portion of the light liquid phase 135 and/or heavy liquid phase 137 fed to the acetaldehyde or PRC removal system is between 1% and 99% of the mass flow of one of the light liquid phase 133 and/or heavy liquid phase 134 such as 1 to 50%, 2 to 45%, 5 to 40%, 5 to 30% or 5 to 20%. Additionally, in some embodiments, a portion of both light liquid phase 135 and heavy liquid phase 137 may be fed to an acetaldehyde or PRC removal system. The portion of the light liquid phase 135 that is not fed to the acetaldehyde or PRC removal system may be refluxed to the first column or recycled to the reactor as described herein. The portion of heavy liquid phase 137 that is not fed to the acetaldehyde or PRC removal system may be recycled to the reactor. Although some of the heavy liquid phase 137 may be returned to the first column, it is preferred to return the heavy liquid phase 137 enriched in methyl iodide to the reactor.

In one embodiment, a portion of the light liquid phase 135 and/or the heavy liquid phase 137 is fed to a distillation column that enriches the overheads with acetaldehyde and methyl iodide. Depending on the configuration, there may be two separate distillation columns, the overhead of the second column being rich in acetaldehyde and methyl iodide. Dimethyl ether, which can be formed in situ, may also be present overhead. The overhead may be subjected to one or more extraction stages to remove the methyl iodide-rich raffinate and extractant. A portion of the raffinate may be returned to the distillation column, first column, overhead decanter and/or reactor. For example, if heavy liquid phase 137 is processed in a PRC removal system, it may be desirable to return a portion of the raffinate to the distillation column or reactor. Also, for example, if the light liquid phase 135 is processed in a PRC removal system, it may be desirable to return a portion of the raffinate back to the first column, overhead decanter or reactor. In some embodiments, the extractant is further distilled to remove water and returned to one or more extraction stages containing more methyl acetate and methyl iodide than the light liquid phase (135), also in the reactor (104) and/or Alternatively, it may be recycled to the first column 124.

적합한 정제 공정은 본원에 참고로 인용된 US6143930, US6339171, US7223883, US7223886, US8076507, US20130303800, US20130310603, US20090036710, US20090062525, US20120132515, US20130026458, US201300116470, US20130204014, US20130261334, US20130264186 또는 Us201330281735에 개시된 것들을 포함한다.

Product purification system and process

In an embodiment, acetic acid stream 128 may be subjected to further purification, such as drying column 130, wherein acetic acid is collected as column bottoms and aqueous overheads are collected in overhead decanter 148 and their Some may be refluxed back to drying column 130 before returning to reactor 104. Another embodiment is to direct the acetic acid to a heavy ends column (see WO0216297) and/or contact it with one or more absorbents, adsorbents or ion exchange resins in a resin bed or guard column 200, as fully described in the following literature to process including the removal of various impurities and the like in the product purification zone of (see US6657078). As shown, drying column 130 separates acetic acid sidedraw 128 into an overhead stream composed primarily of water and a bottoms stream composed primarily of acetic acid. The overhead stream is cooled and condensed in a phase separation unit, for example decanter 148, to form light and heavy phases. As shown, part of the light phase is refluxed and the remaining light phase is returned to the reactor. The heavy phase, which is typically an emulsion comprising water and methyl iodide, is preferably returned in its entirety to the reactor. An exemplary composition for the light phase of the drying column overhead is provided in Table 3 below.

In an embodiment, a small amount of an alkaline component such as KOH may be added to sidedraw 128 prior to entering drying column 130. In another embodiment, the alkaline component is also added to drying column 130 at the same elevation level as stream 128 entering drying column 130 or at a level above that of stream 128 entering drying column 130. can be added to This addition can neutralize HI in the column.

In an embodiment, the drying column bottoms stream may comprise or consist essentially of acetic acid. In an embodiment, the drying column bottoms stream comprises acetic acid in an amount greater than 90 weight percent, such as greater than 95 weight percent or greater than 98 weight percent. In an embodiment, this stream will also be essentially anhydrous, for example containing less than 0.15% water, such as less than 0.12% water or less than 0.1% water by weight. However, as discussed, the stream may contain varying levels of impurities.

In Figure 1, the crude acid product exits as a residue in drying column bottoms stream 146. In an embodiment, the crude acid product from drying column 130 may be taken from the side stream at a location slightly above the bottom of column 130. This side stream can be withdrawn in either the liquid or vapor phase. When venting to the vapor phase, additional condensation and cooling may be required prior to removing alkaline contaminants, for example lithium contaminants. For example, the crude acid product may be taken as a side stream from the bottom of the column, while the residue stream from the base of drying column 130 may be withdrawn and removed or recycled. This side stream contains the crude acetic acid product which is sent to a cation exchange resin to remove lithium. This may allow separation of the high boiling point fraction from the crude acid product in the residue stream. In an embodiment, the residue stream is discarded or purged from process 100.

In an embodiment, the crude acid product produced by drying column 130 is further processed by passing it through a series of metal functionalized iodide free ion exchange resins before being stored or transported to commercial use. In an embodiment, the process for making acetic acid further comprises introducing a lithium compound into the reactor to maintain a concentration of lithium acetate in the reaction medium in an amount of 0.3 to 0.7 weight percent. In an embodiment, the amount of lithium compound is introduced into the reactor to maintain the concentration of hydrogen iodide in the reaction medium in an amount of 0.1 to 1.3 weight percent. In an embodiment, the concentration of rhodium catalyst is maintained in an amount of 300 to 3000 wppm in the reaction medium and the concentration of water is in an amount of 0.1 to 4.1 weight percent of the reaction medium, based on the total amount of reaction medium present inside the carbonylation reactor. , and the concentration of methyl acetate is maintained in an amount of 0.6 to 4.1% by weight of the reaction medium.

In an embodiment, the lithium compound introduced into the reactor is selected from the group consisting of lithium acetate, lithium carboxylate, lithium carbonate, lithium hydroxide, other organolithium salts, and mixtures thereof. In an embodiment, the lithium compound is soluble in the reaction medium. In an embodiment, lithium acetate dihydrate may be used as the source of the lithium compound.

Lithium acetate reacts with hydrogen iodide to form lithium iodide and acetic acid according to the following equilibrium reaction (I):

LiOAc + HI → LiI + HOAc (I)

Lithium acetate is believed to provide improved control of the hydrogen iodide concentration compared to other acetates present in the reaction medium, such as methyl acetate. Without wishing to be bound by theory, lithium acetate is the conjugate base of acetic acid and thus has reactivity to hydrogen iodide by an acid-base reaction. This property is believed to provide an equilibrium of reaction (I) that favors the reaction product in addition to that produced by the corresponding equilibrium of methyl acetate and hydrogen iodide. This improved equilibrium is favored by water concentrations of less than 4.1 weight in the reaction medium. In addition, the relatively low volatility compared to methyl acetate allows lithium acetate to remain in the reaction medium, except for volatility loss and entrainment as a small amount of vapor crude product. In contrast, the relatively high volatility of methyl acetate causes the material to distill in refinery trains, making methyl acetate more difficult to control. Lithium acetate is much more easily maintained and controlled in the process at constant low concentrations of hydrogen iodide. Thus, relatively small amounts of lithium acetate can be used relative to the amount of methyl acetate needed to control the hydrogen iodide concentration in the reaction medium. It was further found that lithium acetate was at least three times more effective than methyl acetate in catalyzing the oxidative addition of methyl iodide to the rhodium[I] complex.

In an embodiment, the concentration of lithium acetate in the reaction medium is greater than or equal to 0.3 weight percent, or greater than or equal to 0.35 weight percent, or greater than or equal to 0.4 weight percent, or greater than or equal to 0.45 weight percent, or greater than or equal to 0.5 weight percent, as measured according to perchloric acid titration to the potentiometric endpoint. and/or, in embodiments, the concentration of lithium acetate in the reaction medium is maintained at 0.7 wt% or less, or 0.65 wt% or less, or 0.6 wt% or less, or 0.55 wt% or less.

It has been found that excess lithium acetate in the reaction medium can adversely affect other compounds in the reaction medium, resulting in reduced productivity. Conversely, a concentration of lithium acetate in the reaction medium of less than about 0.3 weight percent results in a lack of control over the hydrogen iodide concentration within the reaction medium.

In an embodiment, the lithium compound may be introduced continuously or intermittently into the reaction medium. In an embodiment, the lithium compound is introduced during reactor start-up. In an embodiment, the lithium compound is introduced intermittently to replace accompanying losses.

A series of experiments were conducted to demonstrate the facilitating effect of lithium acetate in the carbonylation reactor and to determine the effect of lithium acetate on the oxidative addition of methyl iodide to the rhodium complex, Li[RhI ₂ (CO) ₂ ] confirmed the facilitating effect of lithium acetate on the reaction rate. A linear increase in reaction rate associated with increasing the concentration of lithium acetate was observed. This association is indicative of a first order facilitating effect of the reaction between methyl iodide and Li[RhI ₂ (CO) ₂ ]. These experiments further show a non-zero intercept, indicating that lithium acetate is not required for the MeI-Rh(I) reaction to occur, but lithium acetate provides a significant facilitating effect even at low concentrations. confirmed

In an embodiment, the process further comprises maintaining the concentration of butyl acetate in the acetic acid product below 10 wppm without directly removing the butyl acetate from the product acetic acid. In an embodiment, the concentration of butyl acetate in the final acetic acid product is determined by removing acetaldehyde from the reaction medium, such as from a stream derived from the reaction medium, and/or the reaction temperature, and/or hydrogen partial pressure, and /or by controlling the metal catalyst concentration in the reaction medium, it can be maintained below 10 ppm. In an embodiment, the concentration of butyl acetate in the final acetic acid product is from 100 to 3000 wppm, based on the total weight of reaction medium, at a carbonylation reaction temperature of 150 °C to 250 °C, a hydrogen partial pressure in the carbonylation reactor of 0.3 to 2 atm, and/or a concentration of acetaldehyde in the reaction medium of less than or equal to 1500 ppm.

In an embodiment, the acetic acid product formed according to the manufacturing process disclosed herein has, based on the total weight of the acetic acid product, 10 wppm or less, or 9 wppm or less, or 8 wppm or less, or 6 wppm or less, or 2 wppm or less butyl It has the concentration of acetate. In an embodiment, the acetic acid product is substantially free of butyl acetate, i.e., concentrations of butyl acetate of 0.05 wppm or less are undetectable by detection means known in the art. In an embodiment, the acetic acid product may also have a propionic acid concentration of less than 250 wppm, or less than 225 ppm, or less than 200 wppm.

In an embodiment, the concentration of butyl acetate in the acetic acid product can be controlled by controlling the concentration of acetaldehyde in the reaction medium. Without being bound by theory, it is believed that butyl acetate is a by-product caused by the aldol condensation of acetaldehyde. Applicant believes that by maintaining the concentration of acetaldehyde in the reaction medium below 1500 wppm, the concentration of butyl acetate in the final acetic acid product can be controlled to less than 10 wppm. In an embodiment, the concentration of acetaldehyde in the reaction medium is maintained at 1500 wppm or less, or 900 wppm or less, or 500 wppm or less, or 400 wppm or less, based on the total weight of the reaction medium.

In an embodiment, the concentration of butyl acetate in the acetic acid product can be controlled by controlling the reaction temperature of the carbonylation reactor to a temperature of at least 150°C, or at least 180°C, and at most 250°C, or at most 225°C, and/or The hydrogen partial pressure in the carbonylation reactor can be controlled to be 0.3 atm or more, or 0.35 atm or more, or 0.4 atm or more, or 0.5 atm or more, and 2 atm or less, or 1.5 atm or less, or 1 atm or less.

While relatively high hydrogen partial pressures result in improved reaction rates, selectivity, improved catalytic activity, and reduced temperatures, Applicants have discovered that as hydrogen partial pressure is increased, impurity production, including butyl acetate, also increases.

In an embodiment, the hydrogen partial pressure may be controlled by varying the amount of hydrogen present in the carbon monoxide source and/or by increasing or decreasing the reactor vent flow to obtain the desired hydrogen partial pressure inside the carbonylation reactor.

A series of experiments were conducted to demonstrate the effect of the concentration of acetaldehyde in the reaction medium and the partial pressure of hydrogen on the concentration of butyl acetate in the final acetic acid product. These experiments confirmed a relationship between the reduced butyl acetate concentration in the final acetic acid product and the relatively low concentration of acetaldehyde in the reaction medium and/or relatively low hydrogen partial pressure in the carbonylation reactor. Experiments in which the concentration of acetaldehyde in the reactor was maintained below 1500 ppm and the reactor hydrogen partial pressure was maintained below 0.6 atm resulted in butyl acetate levels of less than 10 wppm in the final acetic acid product. Another experiment in which the concentration of acetaldehyde in the reactor was maintained below 1500 ppm and the reactor hydrogen partial pressure was maintained below 0.46 atm showed that this resulted in a concentration of butyl acetate in the final acetic acid product of less than 8 wppm. Similar conditions with a hydrogen partial pressure of 0.30 atm produced a butyl acetate level of less than 6 wppm in the final acetic acid product, and a hydrogen partial pressure of 0.60 atm produced a concentration of butyl acetate in the final acetic acid product of less than 0.2 wppm. However, comparative experiments in which the hydrogen partial pressures were 0.4 and 0.3, respectively, but the concentration of acetaldehyde in the reactor exceeded 1500 wppm due to the absence of an aldehyde removal system, produced final acetic acid products with butal acetate levels of 13 wppm and 16 wppm, respectively. Created.

Applicants have further confirmed that the concentration of propionic acid in the final acetic acid product can be influenced by the concentration of butyl acetate in the acetic acid product. Thus, by controlling the concentration of butyl acetate in the final acetic acid product to 10 wppm or less, the concentration of propionic acid in the final acetic acid product can be controlled to less than 250 wppm, or less than 225 ppm, or less than 200 wppm. Similarly, by controlling the ethanol (which may be present as an impurity in the methanol source) content in the reactor feed, the concentrations of propionic acid and butyl acetate in the final acetic acid product can also be controlled. In an embodiment, the concentration of ethanol in the methanol feed to the carbonylation reactor is controlled to 150 wppm or less. In an embodiment, the concentration of ethanol, if present, in the methanol feed to the reactor is 100 wppm or less, or 50 wppm or less, or 25 wppm or less.

Applicants have further discovered that the formation of ethyl iodide can be influenced by many variables including the concentrations of acetaldehyde, ethyl acetate, methyl acetate and methyl iodide in the reaction medium. Additionally, it has been found that the ethanol content in the methanol source, the hydrogen partial pressure and the hydrogen content in the carbon monoxide source affect the concentration of ethyl iodide in the reaction medium and thus the propionic acid concentration in the final acetic acid product.

In an embodiment, the concentration of ethyl iodide in the reaction medium is maintained/controlled at 750 wppm or less, or 650 wppm or less, or 550 wppm or less, or 450 wppm or less, or 350 wppm or less. In other embodiments, the concentration of ethyl iodide in the reaction medium is at least 1 wppm, or at least 5 wppm, or at least 10 wppm, or at least 20 wppm, or at least 25 wppm, and at most 650 wppm, or at most 550 wppm, or Maintained/controlled below 450 wppm, or below 350 wppm.

In an embodiment, the propionic acid concentration in the acetic acid product can be further maintained below 250 wppm by maintaining the ethyl iodide concentration in the reaction medium below 750 wppm without removing the propionic acid from the acetic acid product.

In an embodiment, the ethyl iodide concentration in the reaction medium and propionic acid in the acetic acid product may be present in a weight ratio of 3:1 to 1:2, or 5:2 to 1:2, or 2:1 to 1:2. In an embodiment, the acetaldehyde:ethyl iodide concentration in the reaction medium is maintained at 2:1 to 20:1, or 15:1 to 2:1, or 9:1 to 2:1.

In an embodiment, the ethyl iodide concentration in the reaction medium can be maintained by controlling one or more of the hydrogen partial pressure, the concentration of methyl acetate, the concentration of methyl iodide, and/or the concentration of acetaldehyde in the reaction medium.

of acetaldehyde and other reaction conditions for the formation of ethyl showing the relationship between the concentration of acetaldehyde and the concentration of ethyl iodide in the reaction medium, and the relationship between the concentration in the reactor in ethyl iodide and the concentration of propionic acid in the final acetic acid product. A series of experiments were conducted to determine the effect. Generally, concentrations of less than 750 wppm of ethyl iodide and less than 1500 wppm of acetaldehyde in the reaction medium resulted in concentrations of less than 250 wppm of propionic acid in the acetic acid product.

iodide Use of ablation layer/ion exchange resin

In an embodiment, the product acetic acid stream can be contaminated with a halide (eg, iodide) and lithium can be contacted with a cation exchange resin in acid-form, then silver, mercury, palladium and rhodium under a range of operating conditions. may be contacted with a metal-exchanged ion exchange resin having an acid cation exchange site comprising one or more metals selected from the group consisting of In an embodiment, the ion exchange resin composition is provided in a stationary bed. The use of fixed iodide removal beds to purify contaminated carboxylic acid streams is well documented in the art (see, eg, US Pat. Nos. 4,615,806, 5,653,853, 5,731,252 and 6,225,498, incorporated herein by reference). Generally, a contaminated liquid carboxylic acid stream is contacted with the ion exchange resin composition described above by flowing through a series of static immobilizing beds. Lithium contaminants are removed in acid form by cation exchangers. Halide contaminants, such as iodide contaminants, are then removed by reaction of the metal-exchanged ion exchange resin with the metal to form metal iodides. In some embodiments, a hydrocarbon moiety such as a methyl group capable of bonding with iodide can esterify a carboxylic acid. For example, in the case of acetic acid contaminated with methyl iodide, methyl acetate will be produced as a by-product of iodide removal. Formation of these esterification products typically has no detrimental effect on the treated carboxylic acid stream.

A similar iodide contamination problem may exist in acetic anhydride produced via a rhodium-iodide catalytic system. Thus, the process of the present invention can alternatively be used for the purification of a crude acetic anhydride product stream.

Acid-type cation exchangers suitable for removing metal ion contaminants in the present invention include strong acid cation exchange resins such as Amberlyst® 15 resin (DOW), Purolite C145 or Purolite CT145. may include macroreticular or macroporous resins. The resin may also be a strong acid cation exchange mesoporous resin in acid form. Chelating resins and zeolites may also be used.

Suitably stable ion exchange resins used in connection with the present invention for making silver or mercury-exchange resins for iodide removal are typically of the "RS03H" type classified as "strong acids", i. It is a sulfonic acid, a cation exchange resin. Particularly suitable ion exchange substrates include Amberlyst 15, Amberlyst 35 and Amberlyst 36 resins (DOW) which are suitable for use at elevated temperatures. Other stable ion exchange substrates, such as zeolites, can be used provided that the material is stable in the organic medium under the conditions of interest, i.e. it does not chemically decompose or release unacceptable amounts of silver or mercury into the organic medium. Zeolite cation exchange substrates are disclosed, for example, in US 5,962,735, the disclosure of which is incorporated herein by reference.

At temperatures above about 50° C., silver or mercury exchanged cationic substrates tend to release small amounts of silver or mercury, less than 500 ppb, and thus silver or mercury exchanged substrates are chemically stable under the conditions of interest. More preferably, the silver loss is less than 100 ppb into the organic medium, more preferably less than 20 ppb into the organic medium. Silver losses may be slightly higher at start-up. In any case, if desired, a layer of the cationic material in acid form is disposed upstream of the silver or mercury exchange material and downstream of the silver or mercury exchange material in addition to the layer of the cationic material in acid form so that any silver or mercury released can capture

The pressure during the contacting step with the exchange resin is limited only by the physical strength of the resin. In one embodiment, the contacting is performed at a pressure ranging from 0.1 MPa to 1 MPa such as from 0.1 MPa to 0.8 MPa or from 0.1 MPa to 0.5 MPa. However, for convenience, both the pressure and temperature can preferably be set such that the contaminated carboxylic acid stream is treated as a liquid. Thus, for example, when operated at atmospheric pressure, which is generally preferred based on economic considerations, the temperature may range from 17° C. (the freezing point of acetic acid) to 118° C. (the boiling point of acetic acid). It is within the ability of one skilled in the art to determine similar ranges for product streams comprising other carboxylic acid compounds. The temperature of the contacting step is preferably kept low enough to minimize resin degradation. In one embodiment, the contacting is performed at a temperature in the range of 25°C to 120°C, such as in the range of 25°C to 100°C or 50°C to 100°C. Some cationic macroreticular resins typically begin to decompose significantly (via the mechanism of acid-catalyzed aromatic desulfurization) at temperatures of 150°C. Carboxylic acids having less than 5 carbon atoms, for example less than 3 carbon atoms, remain liquid at these temperatures. Therefore, the temperature during contact must be kept below the decomposition temperature of the resin used. In some embodiments, the operating temperature is maintained below the temperature limits of the resin consistent with liquid phase operation and desirable kinetics for lithium and/or halide removal.

The composition of the resin bed in the acetic acid purification train can vary, but the cationic exchanger must be upstream of the metal-exchanged resin. In a preferred embodiment, the resin bed is constructed after the final drying column. Preferably, the resin layer is formed at a location where the temperature of the crude acid product is low, for example less than 120°C or less than 100°C. The stream in contact with the acid-type cation exchange resin and the stream in contact with the metal-exchanged resin may be conditioned to the same or different temperatures. For example, the stream contacting the acid-form cation exchange resin may be conditioned to a temperature of 25°C to 120°C, such as 25°C to 85°C, 40°C to 70°C, such as 40°C to 60°C, while , the stream contacting the metal-exchanged resin may be conditioned to a temperature of 50°C to 100°C, for example 50°C to 85°C, 55°C to 75°C or 60°C to 70°C. In addition to the advantages discussed above, low-temperature operation can reduce corrosion compared to high-temperature operation. Low temperature operation provides less formation of corrosive metal contaminants that can reduce overall resin life as discussed above. In addition, since corrosion is less when the operating temperature is low, there is no need to manufacture the container from expensive corrosion-resistant metal, and low-grade metal, such as standard stainless steel, can be used.

Referring again to FIG. 1 , the drying column bottoms stream is first passed through a bed of cation exchange resin 200 to remove lithium ions. Although one cation exchange resin bed 200 is shown, it should be understood that multiple cation exchange resin beds may be used in series or parallel. The cation exchange bed can also remove other cations present in the stream, such as potassium when added to the drying column 130 as a potassium salt selected from the group consisting of potassium acetate, potassium carbonate and potassium hydroxide and a corrosive metal. can The resulting exchanged stream, for example an intermediate acid product, is then passed through a bed of metal-exchanged ion exchange resin having acid cation exchange sites comprising at least one metal selected from the group consisting of silver, mercury, palladium and rhodium to obtain the Iodide can be removed from the stream to produce purified product 146. Although purification resin is shown through block 200, it should be understood that multiple layers of metal-exchanged ion exchange resin may be used in series or parallel. Prior to contact with the resin layer, a heat exchanger (not shown) may be placed prior to either layer of resin to adjust the temperature of streams 146 and 182 to an appropriate temperature prior to contact with the resin layer. Similarly, crude acetic acid product may be fed to the cation exchange resin bed from the drying column side stream. A heat exchanger or condenser may be placed prior to either bed of resin to bring the temperature of the stream to an appropriate temperature prior to contact with the bed of resin.

In one embodiment, the flow rate through the resin bed is from 0.1 bed volume/hour ("BV/hr") to 50 BV/hr, such as from 1 BV/hr to 20 BV/hr or from 6 BV/hr to 10 Bv/hr. is the range of The volume of a layer of organic medium is the volume of the medium equal to the volume occupied by the resin layer. A flow rate of 1 BV/hr means that an amount of organic liquid equal to the volume occupied by the resin layer passes through the resin layer in one hour.

A purified acetic acid composition is obtained as a result of treating the resin bed. The purified acetic acid composition comprises less than 100 wppb in one embodiment, such as less than 90 wppb, less than 50 wppb or less than 25 wppb. In one embodiment, the purified acetic acid composition comprises less than 100 wppb lithium, such as less than 50 wppb, less than 20 wppb or less than 10 wppb lithium. Regarding ranges, the purified acetic acid composition may contain from 0 to 100 wppb of iodide such as from 0 to 50 wppb; and/or 0 to 100 wppb of lithium, for example 1 to 50 wppb. In other embodiments, the resin layer removes at least 25 wt% iodide from the crude acetic acid product, such as at least 50 wt% or at least 75 wt%. In one embodiment, the resin bed removes at least 25%, such as at least 50% or at least 75% lithium by weight of the crude acetic acid product.

Thus, in an embodiment, product acetic acid or one or more intermediates in a recycle stream of the process may be contacted with one or more absorbents, adsorbents, or ion exchange resins, collectively referred to herein as purification resins. Acetic acid is contacted within the resin bed or guard column 200 to remove various impurities to produce the final acetic acid product.

Impurities removed by the purification resin may include alkyl iodides. In particular, alkyl iodides contain from 1 to about 20 carbon atoms. Other impurities include various corrosive metals such as chromium, nickel, iron and the like.

Purifying resins suitable for the purposes herein include macroreticular, strong acid cation exchange resins in which at least 1% of their active sites have been converted to the silver or mercury form. The amount of silver or mercury associated with the resin is from 1 to 100% of the active sites of the resin, or from about 25 to about 75%, or at least about 50% of the active sites, which can be converted to the silver or mercury form (see US4615806, the contents of which are incorporated herein by reference). Other suitable examples include US5139981 which relates to the removal of iodide from liquid carboxylic acids contaminated with halide impurities by contacting the liquid halide contaminant acid with a silver(I) exchanged macroreticular resin. Suitable examples of purification resins include Amberlyst 15 resin (Rohm and Haas), zeolite cationic ion exchange substrate (see US596273), and the like. Other suitable purification resins and methods include those disclosed in US5227524, US5801279, US5220058, EP0685445 and US6657078, the contents of which are incorporated herein by reference.

In an embodiment, the acetic acid is contacted with the purification resin at a temperature of from about 50° C. or about 60° C. to about 100° C. or about 150° C. or greater, depending on the type of purification resin used.

In an embodiment, the flow rate of acetic acid through the column can be from about 0.5 to about 20 bed volume per hour (BV/hr), where bed volume is defined as the volume occupied by resin in the bed. In an embodiment, the flow rate may be about 6 to about 10 BV/hr or about 7 to 8 BV/hr.

In an embodiment, the column may include an anionic guard layer comprising a pyridine or pyrrolidone resin. As used herein, the terms "pyridine resin", "pyridine ring-containing polymer", "pyridine polymer" and the like refer to a polymer containing a substituted or unsubstituted pyridine ring or a substituted or unsubstituted pyridine-containing polycondensation ring such as a quinoline ring. indicates In embodiments, the resin may include a high degree of crosslinking, i.e. greater than 10% by weight. Substituents include substituents that are inert to the conditions of the methanol carbonylation process, such as alkyl groups and alkoxy groups. Suitable examples of insoluble pyridine ring-containing polymers are those obtained by reaction of vinylpyridine and divinyl monomers or by reaction of vinylpyridine and divinyl monomer-containing vinyl monomers such as copolymers of 4-vinylpyridine and divinylbenzene. , copolymers of 2-vinylpyridine and divinylbenzene, copolymers of styrene, vinylbenzene and divinylbenzene, copolymers of vinylmethylpyridine and divinylbenzene and copolymers of vinylpyridine, methyl acrylate and ethyl diacrylate (See US5334755, the contents of which are incorporated herein by reference).

Suitable "pyrrolidone resins", "pyrrolidone ring-containing polymers", "pyrrolidone polymers" and the like include polymers containing substituted or unsubstituted pyrrolidone rings. Substituents may include substituents that are inert to the methanol carbonylation medium, such as alkyl groups and alkoxy groups. Examples of insoluble pyrrolidone ring-containing polymers include those obtained by the reaction of vinyl pyrrolidone and divinyl monomer-containing vinyl monomers such as copolymers of vinyl pyrrolidone and divinyl benzene. Suitable examples of pyrrolidone polymers include those disclosed in US5466874, US5286826, US4786699, US4139688, the disclosures of which are incorporated herein by reference, and are available from Reilley Tar and Chemical Corporation, Indianapolis, USA. ), including those marketed under the trade name Reillex.

In an embodiment, the nitrogen heterocyclic ring-containing polymer may be at least 10% or at least 15% or at least 20% and less than 50% or less than 60% or less than 75% crosslinked to provide mechanical strength, wherein , "degree of cross-linking" means the content expressed in weight percent of divinyl monomers or other cross-linking moieties.

In an embodiment, suitable pyridine or pyrrolidone insoluble polymers include the free base form and/or the N-oxide form and/or the quaternized form. In an embodiment, the insoluble, pyridine or pyrrolidone ring-containing polymer may be in the form of beads or granules or spheres having a particle diameter of 0.01 to 2 mm or 0.1 to 1 mm or 0.25 to 0.7 mm. Commercially available pyridine-containing polymers include Reillex-425 (Reillex Tar and Chemical Corporation), KEX-316, KEX-501 and KEX-212 (Koei Chemical Co., Ltd.) products), etc.

In an embodiment, product acetic acid exits drying column 130 at or near column bottom via stream 146 and is contacted with one or more resins in a column containing purified resins. As used herein, a column comprising purification resin may be referred to as a purification column, a guard bed assembly or column, or simply a column. These terms are used interchangeably herein. A tablet or guard layer assembly is generally indicated at 200 in FIG. 1 .

In an embodiment, as shown in FIG. 2 , guard layer assembly 200 includes one or more processing devices, such as columns 202 including inlet ends 206 and 210 and outlet ends 208 and 212, respectively, and column 204. The inlet is separated from the outlet by internal chambers 214 and 216. Quantities of purification resins 218 and 220 are placed within the inner chamber.

Acetic acid from the process having a first concentration 146 of impurities is passed through internal chambers 214 and 216 while in contact with purification resins 218 and 220 at a temperature and flow rate sufficient to produce a purified acetic acid stream 222. In this case, the impurity is present at a second concentration less than the first impurity concentration. Accordingly, the second concentration of the impurity may be zero or otherwise undetectable.

In an embodiment, the guard layer assembly may further include heat exchangers 224 and 226 to control the temperature at which the acetic acid contacts the purification resin. In an embodiment, columns 202 and 204 are plug flow columns, which flow from top to bottom by gravity. However, devices that flow against gravity from the lower inlet end to the upper outlet end are also contemplated.

In an embodiment, the first column 202 may include an outlet end 208 in direct fluid communication with the inlet end 210 of the second column 204 . In an embodiment, the conduits between the various devices can be configured such that any column of the plurality of columns is a first processing device and any remaining columns can be placed in series in series. In embodiments, a plurality of columns may be arranged in a parallel configuration.

In embodiments, the purification resin 218 of the first column 202 may be different from the purification resin 220 of the second column 204 and/or the temperature of the first column 202 may be different from that of the second column 204. ) and/or the volume of the inner chamber 214 of the first column 202 can be different than the volume of the inner chamber 216 of the second column 204 .

As shown in FIG. 3 , in an embodiment, a column 400 includes an interior chamber 402 bounded by a plurality of sides 404 arranged radially about a central axis 406 . In an embodiment, column 400 includes an infinite number of sides, ie has a circular cross-section. Column 400 further includes an inlet end 408 longitudinally separated and in fluid communication with outlet end 410 through interior chamber 402 . In an embodiment, the column 400 further includes a plurality of sampling ports 412 disposed through at least one of the sides 404 . The sampling port may be a solid sampling port, a liquid sampling port or a combination thereof.

As shown in FIG. 4 , in an embodiment, each sampling port 412 has a sample inlet 416 located within the internal chamber 402 and an open position (a flow control element such as a ball or ball valve). a first open flow path 414 between a first flow control element 418 operable between a closed position (as shown at 420) and a closed position (as shown at flow control element 418); At this time, the flow control element is located external to the inner chamber 402 , ie to the outer environment 422 . The term "open flow path" means a flow path with dimensions configured to permit the passage of liquid and solid materials. Therefore, the relative size of the open flow path must be determined with respect to the average particle size of the solid or semi-solid material passing through it.

When the flow control element is in the open position, fluid communication is established between the inner chamber 402 and the outer environment 422 . In an embodiment, the first flow path 414 and the second flow path 424 are each in fluid communication with the external environment 422 when the corresponding flow control elements 418 and 420 are in an open position. When the flow control element is in the closed position, fluid communication between the inner chamber 402 and the outer environment 422 is prevented.

In an embodiment, the sample port comprises a porous element 426 disposed between the sample inlet 416 and a second flow control element 420 operable between open and closed positions located outside the internal chamber 402. It further includes a second flow path 424 that

In an embodiment, the second flow path 424 includes a portion of the first flow path 414 between the sample inlet 416 and the first flow control element 418 . thus,

In an embodiment, the second flow path can be a “T-plane” or “Y-plane” orientation of the first flow path, such that the sample exiting through the first control element 418 flows through the second flow control element 420. is taken from the inner chamber 402 at the same location as the sample exiting through.

In an embodiment, as shown in FIG. 3 , the first flow path 414 , the second flow path 424 , or both may be a heat exchanger 428 located between the sample inlet 416 and the external environment 422 . ) is further included. In an embodiment, heat exchanger 428 may be removably attached to a portion of the flow path past the flow control element as shown. Thus, if the inner chamber is hot, a heat exchanger 428, also referred to as a "sample cooler", i.e., one cooled tubing in a bucket of ice water, may be used to obtain a sample of the inner chamber 402.

In an embodiment, the first flow path 414 is located within a first conduit 430 having a first outlet end 432 equipped with a first valve 434 comprising a first flow control element 418 do. In embodiments, the valve may be a ball valve, gate valve, and/or the like. In an embodiment, the first valve is a harsh service ball valve with a seat flush system 436 to prevent particulate matter, such as ion exchange resin, located in the internal chamber 402 from clogging the valve after sample collection. do.

In an embodiment, the second flow path 424 is located at least partially within a second conduit 438 attached to the first conduit 430 at an attachment point 440 and includes a second flow control element 420. and a second outlet end 442 with a second valve 444 for In an embodiment, porous element 426 is positioned at or near attachment point 440 or at or near second outlet end 442 or a combination thereof. In an embodiment, the porous element includes a screen, generally designated 446, a porous frit, a filter element, or a combination thereof. In embodiments, when a plurality of porous elements are utilized, the exclusion size of the elements may vary. For example, in an embodiment, the screen or filter element 446 of the porous element 426 is 100% in a first position depending on the relative size of the particulate matter (eg, purified resin) contained within the internal chamber 402. It may be a mesh screen and in a second downstream location it may be a 200 mesh screen.

In an embodiment, the first open flow path 414 allows both liquid 450 and solids 448 from the internal chamber 402 to flow from the sample inlet 416 through the first flow control element 418 in the open position. The second flow path 424 is configured and dimensioned to flow into the external environment 422, and the second flow path 424 allows the liquid 450 present in the internal chamber 402 to flow from the sample inlet 416 to the porous element 426, in an open position. At least a portion of the solid or semi-solid material (448) present in the inner chamber (402) flows through the second flow control element (420) to the external environment (422) while flowing through the second flow control element (420). It is constructed and dimensioned to exclude

In an embodiment, at least a portion 456 of the first flow path 414 extends into the interior chamber 402 remote from the interior surface 458 of the side 404 on which the sampling port 412 is disposed. It is positioned within the conduit 430 such that the sample inlet 416 is positioned within the inner chamber 402 spaced apart from the side 404 .

As shown in FIG. 3 , in an embodiment, the sample inlet 416 is located on the side 404 where the sampling port 412 is disposed.

In an embodiment, the inner chamber 402 has opposite sides that are less than 50% of the average length 454 of the inner chamber 402 determined parallel to the central axis 406 between the inlet end 408 and the outlet end 406. has an average inner diameter 452 determined perpendicular to the central axis 406 between (404). In an embodiment, the first conduit 430 includes a plurality of sample inlets 416 . In an embodiment, all of the plurality of sample inlets of a single first conduit 430 are positioned coplanar with a plane 460 perpendicular to the central axis 406 .

In an embodiment, the sampling ports 412 are arranged at essentially equal intervals 462 along at least a portion of the side 404 (of one or more of the sides parallel to the central axis from the inlet end 408 to the outlet end 410). along at least part of) are arranged longitudinally.

In an embodiment, the process comprises a column according to any one or combination of embodiments disclosed herein comprising at least one, preferably a plurality of sampling ports 412 according to any one or combination of embodiments disclosed herein. and providing 400 , wherein the inner chamber 402 includes an amount of purifying resin 448 that at least partially fills the inner chamber 402 . A stream to be purified 464, for example an acetic acid stream and/or an intermediate product stream having one or more impurities at a first concentration is then directed through the column and contacted with a purification resin 448 from the inlet end 408. a temperature and flow rate sufficient to produce a purified liquid stream 466, e.g., a purified acetic acid stream and/or an intermediate product stream, having a second concentration of impurities less than the first concentration after passing through the internal chamber 402 at to pass through the outlet end 410.

In an embodiment, the purification resin 448 comprises a macroreticular strong acid ion exchange resin wherein at least about 1% of the active sites of the resin have been converted to the silver or mercury form, and the temperature is at least about 50° C.; Silver or mercury exchanged ion exchange resins are effective at removing about 90% by weight or more of C ₁ -C ₂₀ organic iodides in acetic acid streams.

In an embodiment, the purification resin 448 comprises a plurality of bands 468, 470, a first band 468 and a first band 468 located between the inlet end 408 and the second band 470. It resides in the inner chamber 402 of the second band 470 located between the outlet end 410. In an embodiment, the purified resin in the first band 468 is the same as the purified resin in the second band 470 . In other embodiments, the purified resin in the first band 468 is different than the purified resin in the second band 470 . In an embodiment, the purification resin in the first band 468 is a non-functionalized macroreticular strong acid ion exchange resin and the purification resin in the second band 470 comprises a macroreticular strong acid ion exchange resin, wherein , at least about 1% of the active sites of the resin are converted to the silver or mercury form.

In an embodiment, a method according to one or more embodiments disclosed herein may first move from a closed position to an open position for a time sufficient to obtain a sample comprising liquid 450 and purifying resin 448 from the first sampling port. activating the flow control element 418 and then returning the first flow control element 418 back to the closed position, and/or for a time sufficient to obtain a sample comprising liquid 450 from the first sampling port; Further comprising actuating the second flow control element 420 from the closed position to the open position and then returning the second flow control element 420 back to the closed position.

In embodiments, the method may further comprise analyzing the one or more samples at the corresponding sampling port to determine the concentration of one or more of the one or more impurities. In an embodiment, the method may further include attaching a heat exchanger to the outlet of the sampling port prior to actuating the valve to obtain a sample having a reduced temperature relative to the temperature of the internal chamber. In an embodiment, the process may further include providing a plurality of columns wherein the outlet end of the first column is in direct fluid communication with the inlet end of the second column.

refine column works and monitoring

In an embodiment, the sample obtained from the sampling port may include a sample of the purification resin present in the column, a liquid sample of the acetic acid stream present in the column, or both. The arrangement of the sampling ports allows samples to be obtained at discrete points through the resin layer.

A sampling port may also be located near the final purified acetic acid stream produced by the column.

Determination of the level of impurities present in a sample depends essentially on the type of sample being analyzed. The liquid sample may be suitable for gas chromatography (GC) analysis, high pressure liquid chromatography (HPLC) analysis, which may include normal phase, reverse phase, ion exclusion, ion pairing, size exclusion, ion exchange, as readily understood by those skilled in the art. and ion chromatography techniques. Any type of suitable detector may be used. Similarly, resin samples can be extracted and/or digested allowing any of a variety of chromatographic techniques and/or analyzed via wet chemistry techniques, atomic absorption spectrometry, which include inductively coupled plasma (ICP) analysis, mass spectrometry , ICP-MS and/or the like. In one embodiment, a resin sample can be analyzed using X-ray fluorescence techniques as readily understood by those skilled in the art.

In an embodiment, the sample may be analyzed for halogen or iodide (I) and/or various transition metals from Groups 3 to 12, or corrosive metals typical for acetic acid production such as Fe, Cr and/or Ni; The active site of the resin, which may contain silver and/or mercury, can be analyzed for the presence of converted metals or moieties.

In an embodiment, the combination of using a sampling port and analyzing may include monitoring the ability of the column to remove impurities, diverting the flow around the column, and then characterizing the retention or removal of impurities of the column. It can be used to control column operation in

In an embodiment, the impurity concentration of the sample may be compared to a predetermined impurity concentration value indicating whether the purification resin is working or exhausted. This information can be combined with the location of the sample port such that the sample's impurity concentration indicates depletion of purification resin at a point within the column corresponding to the location of the sample port from which the sample was obtained.

In an embodiment, the resin is discharged when the acetic acid cannot be purified to an acceptable level for longer. In an embodiment, a purified resin is considered "consumed" when the acetic acid in contact with the resin has an iodide concentration greater than 100 ppb weight, an Fe, Cr and/or Ni concentration greater than 500 ppb weight, or a combination thereof. do.

Also, in an embodiment, a resin sample containing greater than about 10% by weight of an impurity is also considered exhausted for purposes herein. However, it should be understood that these levels merely reflect current requirements for product acetic acid, and that any such level may be used. Also, the levels used (when determined) and the impurities analyzed may differ for iodide and corrosive metals depending on the stream in which the column is located.

In an embodiment, an indication of a spent column as determined by a final purified acetic acid sample having an impurity profile above an acceptable level may result in flow through a particular column being stopped and/or diverted through an appropriate column.

In an embodiment, the progress of impurities through the column can be used to determine the rate at which the column is consumed and thus can be used to predict life expectancy or otherwise control the use of the column in a process. In one embodiment, the flow around the column can be stopped or otherwise diverted to determine the discharged resin still close to the end of the column in the final purified acetic acid to allow for resin replacement and/or resin regeneration.

In an embodiment, once the flow of acetic acid through the column is stopped, the resin can be regenerated. In an embodiment, regeneration of the drained resin comprises removing at least a portion of the drained resin from the column and refilling at least a portion of the column with an active purification resin. In an embodiment, at least a portion of the active resin used to recharge the column comprises previously drained resin that has been regenerated to active purified resin. In an embodiment, at least a portion of the spent resin is regenerated within the column to active purification resin, also referred to as in situ regeneration. Regeneration of the resin depends on the type of resin and the impurities removed. The regeneration process may include contacting the resin with suitable solvents, reagents and/or the like.

column resin filling

As shown in FIG. 5 , in an embodiment, a method or process 500 includes providing 502 a column according to any one or combination of embodiments disclosed herein comprising an internal chamber. The process includes disposing a column including one or more sample ports between the column inlet and the column outlet (wherein the one or more sample ports include a liquid sample port, a solid sample port, or both) and one or more sample ports. and opening the port (505).

Next, the method or process includes introducing into the inner chamber an amount of purification resin sufficient to fill a portion of the inner chamber (504). In an embodiment, filling the column comprises opening one or more sample ports. In an embodiment, the sample port may be used to flush the resin, remove vapors from the resin, purge an internal chamber with an inert gas during filling of the resin, and the like.

In an embodiment, the resin may be placed in the column in dry or wet form by manually moving the resin to the top of the column or pumping a slurry into the column. In an embodiment, the resin may be supplied as a slurry in a vessel such as a liquid tote, tank truck or tanker rail car and transferred pneumatically to the column. Thus, in an embodiment, the lower outlet of the vessel containing the slurry comprising the purification resin is in fluid communication with the inner chamber. Thereafter, pressure is applied to the headspace of the vessel in an amount sufficient to pneumatically transfer at least a portion of the slurry from the vessel into the inner chamber (506).

In an embodiment, after the resin has been pneumatically transferred into the column by pumping or pressurizing the vessel, additional water or other solvent may be added to the vessel and the transfer process repeated so that essentially all of the resin is transferred. Prior to and/or during transfer of the resin, in an embodiment, the column and/or vessel is purged with nitrogen or other inert gas to remove oxygen (508).

In an embodiment, the resin may be backwashed 510 using a wash liquid, typically water or other solvent, to remove particulates, foreign matter and man-made products. Washing may last 518 for at least 60 minutes. This backwash can be sent to waste or otherwise recycled, as appropriate. The wash time can last an hour or more at a relatively high flow rate to ensure uniform dispersion of the resin within the column and to avoid pockets in the resin. The wash is then removed from the resin by applying pressure to the top of the column (512), such as with nitrogen, and holding the pressure until gas is blown through the column outlet, indicating that essentially all of the wash has been removed. It can be.

The resin can then be flushed back 514 once again, only this time using acetic acid. In an embodiment, the acidic back flushing is performed at a relatively slow rate and the flow rate of acid to the column base is less than 0.05 bed volume per minute or less than 0.04 bed volume per minute (516). A reverse flush may be performed until all vapor present in the column has been replaced by liquid. In an embodiment, at least a portion of the vapor is removed through one or more sample ports. In an embodiment, only a portion of the inner chamber is initially filled with resin to swell the resin, and in an embodiment, it may be 40% or more when the resin is replaced from water to acetic acid.

Once the resin is backwashed, the column removes the first impurity from the inlet end to the outlet end at a purification temperature and flow rate sufficient to produce a purified acetic acid stream having a second impurity concentration at the outlet end lower than the first impurity concentration. It can be used by inducing a flow of acetic acid having a concentration (520).

As is apparent from the figures and specification presented above, various embodiments are contemplated:

E1. a) providing a processing device column comprising an inner chamber containing an active purification resin positioned between a column inlet and a column outlet, wherein the column has at least one sample port disposed between the column inlet and the column outlet. further comprising, wherein the one or more sample ports include a liquid sample port, a solid sample port, or both; and b) passing through the column at a temperature and flow rate sufficient to produce an acetic acid stream having a first concentration of the impurity and, if any, a purified acetic acid stream having a second concentration of the impurity less than the first concentration. A method comprising flowing through.

E2. The method of embodiment E1, further comprising opening one or more sample ports.

E3. The method of embodiment E1 or E2, wherein the impurity comprises iodine, chromium, nickel, iron, or a combination thereof.

E4. The method of any one of embodiments E1 to E3, wherein the purification resin comprises a macroreticular strong acid ion exchange resin having at least about 1% active sites in the form of silver or mercury.

E5. The method of any one of embodiments E1 to E4, wherein the temperature is at least about 50 °C.

E6. The method of any one of embodiments E1 to E5, wherein obtaining a sample of the purification resin passing through one or more solid sample ports, a liquid sample of the acetic acid stream present in the column passing through one or more liquid sample ports, or a combination thereof and determining the concentration of the impurity in the one or more samples.

E7. The method of embodiment E6, wherein the concentration of the impurity is determined using gas chromatography, high pressure liquid chromatography, atomic absorption, inductively coupled plasma spectroscopy, mass spectroscopy, x-ray fluorescence spectroscopy, or a combination thereof.

E8. The method of embodiment E6 or E7, further comprising comparing the impurity concentration of at least one sample to a predetermined impurity concentration value, and the purification at a point within the column at which the impurity concentration of the sample corresponds to a location of a sample port from which the sample was obtained. The method further comprising the step of determining whether it indicates consumption of resin.

E9. The method of any one of embodiments E1 to E8, further comprising stopping the flow of acetic acid through the column.

E10. The method of any one of embodiments E1 to E9, wherein the flow of acetic acid is stopped before essentially all of the active purification resin present in the column is consumed.

E11. The method of any one of embodiments E1 to E10, further comprising providing a second column comprising an inner chamber comprising an active purification resin positioned between a second column inlet and a second column outlet, and a first concentration of impurities. flowing an acetic acid stream having an acetic acid stream through the second column at a temperature and flow rate sufficient to produce the purified acetic acid stream at the second column outlet having a second concentration of impurities, if any, lower than the first concentration. How to include additional steps.

E12. The method of any one of embodiments E1 to E11, further comprising regenerating at least a portion of said spent resin and resuming flow of said acetic acid stream through said column to produce said purified acetic acid stream.

E13. The method of embodiment E12, wherein regeneration of the spent resin comprises removing at least a portion of the spent resin from the column and refilling at least a portion of the column with an active purification resin.

E14. The method of embodiment E12 or E13, wherein at least a portion of the active resin used to recharge the column comprises previously spent resin that has been regenerated to active purification resin.

E15. The method of any one of embodiments E12 to E14, wherein at least a portion of the spent resin is recycled to the active purification resin in the column.

E16. a) providing a processing device column comprising an inner chamber bounded by a plurality of sides radially disposed about a central axis and having a longitudinally separated inlet end in fluid communication with an outlet end through the inner chamber; ;

b) introducing a sufficient amount of purification resin into the inner chamber to fill the inner chamber portion;

c) flowing an aqueous wash solution from the outlet end through the interior chamber to the inlet end at a flow rate and for a time sufficient to wash and/or remove particulates from the purification resin; and

d) passing an acetic acid stream having a first concentration of the impurity through the column at a temperature and flow rate sufficient to produce a purified acetic acid stream at the column outlet having a second concentration of the impurity, if present, which is less than the first concentration. A method comprising the step of fluidizing.

E17. The method of embodiment E16, wherein the column comprises at least one sample port disposed between the column inlet and the column outlet, wherein the at least one sample port comprises a liquid sample port, a solid sample port, or both, wherein the method further comprises opening one or more sample ports.

E18. The method of embodiment E16 or E17, wherein the aqueous wash liquor is allowed to flow for at least 60 minutes.

E19. The method of any one of embodiments E16 to E18, further comprising, after step (c), directing an amount of inert gas into the column inlet in an amount and at a pressure sufficient to obtain a flow of inert gas through the outlet end. How to.

E20. The method of any one of embodiments E16 to E19, further comprising directing a countercurrent flow of acetic acid to the outlet end at a flow rate and for a time sufficient to remove essentially all vapor from the inner chamber.

E21. The method of embodiment E20, wherein the reverse flush flow of acetic acid has a flow rate of about 0.05 bed volume/minute or less and a time of about 30 minutes or less.

E22. The method of any one of embodiments E16 to E21, wherein directing the purification resin into the inner chamber comprises providing fluid communication between a lower outlet and an inner chamber of a vessel containing a slurry comprising the purification resin; and applying pressure to the headspace of the vessel in an amount sufficient to pneumatically transfer at least a portion of the slurry from the vessel to the inner chamber.

E23. The method according to any one of embodiments E16 to E22, wherein an amount of an inert gas such that the inner chamber and/or the headspace are contained less than 1% by weight prior to introducing the purified resin into the inner chamber; purging the vessel's headspace or both.

E24. The method of any one of embodiments E16 to E23, wherein the impurity comprises iodine, chromium, nickel, iron, or combinations thereof; wherein the purification resin comprises a macroreticular strong acid ion exchange resin having at least about 1% active sites in the form of silver or mercury; wherein the temperature is at least about 50° C., or a combination thereof.

E25. The method of any one of embodiments E16 to E23, wherein the impurity comprises iodine, chromium, nickel, iron, or combinations thereof; wherein the purification resin comprises a macroreticular strong acid ion exchange resin having at least about 1% active sites in the form of silver or mercury; wherein the temperature is at least about 50° C., or a combination thereof.

E26. Any one of embodiments E1 to E15, wherein the step of providing the column comprising an inner chamber comprising an active purification resin positioned between the column inlet and the column outlet is according to any one of embodiments E16 to E25. in, how.

E27. A method comprising: carbonylating at least one compound selected from the group consisting of methanol, dimethyl ether and methyl acetate in the presence of 0.1 to less than 14 weight percent of water, a rhodium catalyst, methyl iodide and lithium iodide to form a reaction medium comprising acetic acid; forming in a reactor;

separating the reaction medium into a liquid recycle stream and a vapor product stream;

separating the vapor product stream in no more than two distillation columns in a first purification train to produce a crude acid product comprising acetic acid comprising lithium cations;

contacting the crude acetic acid product with a cation exchanger in acid form in a first treatment unit to produce an intermediate acid product; and

contacting the intermediate acetic acid product with a metal-exchanged ion exchange resin having an acid cation exchange site in a second processing unit to produce purified acetic acid, wherein the first processing unit, the second processing unit or A method, both of which are according to any one of embodiments E1 to E15.

E28. A method comprising: carbonylating at least one compound selected from the group consisting of methanol, dimethyl ether and methyl acetate in the presence of 0.1 to less than 14 weight percent of water, a rhodium catalyst, methyl iodide and lithium iodide to form a reaction medium comprising acetic acid; forming in a reactor; separating the reaction medium into a liquid recycle stream and a vapor product stream;

separating the vapor product stream in no more than two distillation columns in a first purification train to produce a crude acid product comprising acetic acid comprising lithium cations;

contacting the crude acetic acid product with a first purification resin comprising a cation exchanger in acid form in a first treatment device to produce an intermediate acid product;

contacting the intermediate acetic acid product with a second purification resin comprising a metal-exchanged ion exchange resin having acid cation exchange sites in a second processing unit to produce a purified acetic acid stream, wherein the first processing unit; a second processing device or both individually comprising one or more sampling ports disposed through a side of the processing device;

obtaining a liquid sample of the first purifying resin, the second purifying resin, an acetic acid stream present in the processing unit, or a combination thereof through a corresponding sample port; and

A method comprising determining the concentration of an impurity in one or more samples.

E29. The method according to embodiment E27 or E28, further comprising comparing the impurity concentration of one or more samples to a predetermined impurity concentration value, and at a point within the processing device at which the impurity concentration of the sample corresponds to a location of a sample port from which the sample is obtained. The method further comprising the step of determining whether it indicates consumption of purification resin.

E30. The method of any one of embodiments E27 to E29, comprising stopping the flow of acetic acid through the processing device before essentially all of the active purification resin present in the processing device is consumed, removing at least a portion of the spent resin. further comprising regenerating at least a portion of the spent resin according to any one of embodiments E16 to E26, and resuming flow of the acetic acid stream through the treatment device to produce the purified acetic acid stream. How to.

E31. The method of any one of embodiments E27 to E30, wherein the metal-exchanged ion exchange resin comprises at least 1% strong acid exchange sites incorporating silver.

E32. The method of any one of embodiments E27 to E31, wherein the crude acid product comprises 10 ppm or less lithium.

E33. The method of any one of embodiments E27 to E32, wherein separating the vapor product stream comprises distilling the vapor product stream in a first distillation column and taking a sideraw to obtain a distilled acetic acid product; distilling the distilled acetic acid product in a second distillation column to produce a crude acid product comprising acetic acid and lithium cations.

E34. The method according to any one of embodiments E27 to E33, further comprising adding a potassium salt selected from the group consisting of potassium acetate, potassium carbonate and potassium hydroxide to the distilled acetic acid product prior to distilling it in the second distillation column. further comprising; wherein at least a portion of the potassium is removed by the cation exchanger in acid form.

E35. The method of any one of embodiments E27 to E34, wherein the crude acetic acid product is contacted with the cation exchanger at a temperature of 50 °C to 120 °C.

E36. The method according to any one of embodiments E27 to E35, wherein the intermediate acetic acid product is contacted with a metal-exchanged ion exchange resin at a temperature of 50° C. to 85° C.; or a combination thereof.

E37. The method of any one of embodiments E27 to E36, wherein the intermediate acetic acid product has a lithium ion concentration of less than 50 ppb.

E38. The method of any one of embodiments E27 to E37, wherein the cation exchanger in acid form comprises a strong acid cation exchange macroreticular, macroporous or mesoporous resin in acid form.

E39. The method of any one of embodiments E27 to E38, further comprising treating the purified acetic acid product with a cation exchange resin to recover any silver, mercury, palladium or rhodium.

E40. The process of any one of embodiments E27 to E39, wherein the water concentration in the reaction medium is controlled from 0.1 to 5 weight percent based on the total amount of reaction medium present.

E41. The process according to any one of embodiments E27 to E40, wherein a lithium compound selected from the group consisting of lithium acetate, lithium carboxylate, lithium carbonate, lithium hydroxide, and mixtures thereof is introduced into the reactor to reduce the amount of lithium acetate in the reaction medium. The method further comprising maintaining the concentration between 0.3 and 0.7 by weight.

E42. The method of embodiment E41 further comprising: maintaining a hydrogen iodide concentration in the reaction medium between 0.1 and 1.3 weight percent; maintaining a rhodium catalyst concentration in the reaction medium between 300 and 3000 wppm; maintaining a water concentration in the reaction medium between 0.1 and 4.1 weight percent; maintaining a methyl acetate concentration in the reaction medium between 0.6 and 4.1 weight percent; or a combination thereof.

E43. The method of any one of embodiments E27 to E42, further comprising controlling the butyl acetate concentration in the acetic acid product to 10 wppm or less without directly removing the butyl acetate from the acetic acid product.

E44. The method of embodiment E43, wherein the butyl acetate concentration is controlled by maintaining the acetaldehyde concentration in the reaction medium below 1500 ppm.

E45. The method of embodiment E43 or E44, wherein the butyl acetate concentration is controlled by controlling the temperature in the reactor to between 150 and 250 °C.

E46. The process of any one of embodiments E43 to E45, wherein the butyl acetate concentration is controlled by controlling the hydrogen partial pressure in the reactor to between 0.3 and 2 atm.

E47. The process of any one of embodiments E43 to E45, wherein the butyl acetate concentration is controlled by controlling the rhodium catalyst concentration in the reaction medium from 100 to 3000 wppm.

E48. The method of any one of embodiments E27 to E47, further comprising controlling the ethyl iodide concentration in the reaction medium to 750 wppm or less.

E49. The method of embodiment E48, wherein the propionic acid concentration in the product acetic acid is less than 250 wppm without direct removal of propionic acid from the product acetic acid.

E50. The process of embodiment E48 or E49, wherein the ethyl iodide in the reaction medium and propionic acid in the acetic acid product are present in a weight ratio of 3:1 to 1:2.

E51. The process of any one of embodiments E48 to E50, wherein acetaldehyde and ethyl iodide are present in the reaction medium in a weight ratio of 2:1 to 20:1.

E52. The process of any one of embodiments E48 to E51, wherein the ethanol concentration in the methanol feed to the reactor is less than 150 wppm or a combination thereof.

E53. The method of any one of embodiments E48 to E52, wherein the ethyl iodide concentration in the reaction medium modulates one or more of the hydrogen partial pressure in the carbonylation reactor, the methyl acetate concentration in the reaction medium, and the methyl iodide concentration in the reaction medium. Controlled by doing, how.

Although embodiments have been shown and described in the drawings and foregoing description, they are to be regarded as illustrative and not limiting in nature, with only some embodiments shown and described and all changes and modifications within the spirit of the embodiments. It should be understood that it is desirable to have this protected. The use of the terms ideally, preferably, preferably, preferred, more preferably or exemplary in the foregoing detailed description may indicate that a feature so described may be more desirable or characteristic, but, nevertheless, may not be essential. It should be understood that there are, and embodiments lacking these may be considered within the scope of this invention, which is defined by the following claims. When reading the claims, where terms such as "a", "one or more" or "at least a portion" are used, this is not intended to limit the claims to just one item unless the claim specifically dictates otherwise. have to understand Where the terms “at least some” and/or “some” are used, such items may include some and/or all items, unless specifically stated otherwise.

Claims (20)

A reaction medium comprising acetic acid is introduced into a reactor by carbonylating at least one compound selected from the group consisting of methanol, dimethyl ether and methyl acetate in the presence of 0.1 to 14 weight percent of water, a rhodium catalyst, methyl iodide and lithium iodide. forming;
separating the reaction medium into a liquid recycle stream and a vapor product stream;
separating the vapor product stream in no more than two distillation columns in a primary purification train to produce a crude acetic acid product comprising acetic acid comprising lithium cations;
producing an intermediate acetic acid product by contacting the crude acetic acid product with a first purification resin containing a cation exchanger in acid form in a first treatment device;
contacting the intermediate acetic acid product with a second purification resin comprising a metal-exchanged ion exchange resin having acid cation exchange sites in a second processing unit to produce a purified acetic acid product stream, wherein the first treatment the device, the second processing device, or both individually comprising one or more sampling ports disposed through a side of the processing device;
obtaining a liquid sample of the first purifying resin, the second purifying resin, the acetic acid stream present in the processing device, or a combination thereof through a corresponding sample port; and
determining the concentration of an impurity in one or more samples;
How to include. According to claim 1,
comparing the impurity concentration of one or more samples to a predetermined impurity concentration value; and
determining whether the impurity concentration of the sample indicates consumption of the purification resin at a point within the processing apparatus corresponding to the location of a sample port from which the sample is obtained;
How to further include. According to claim 2,
stopping the flow of acetic acid through the processing device before essentially all of the active purification resin present in the processing device is consumed;
regenerating at least a portion of the spent resin; and
resuming flow of the acetic acid stream through the processing device to produce the purified acetic acid product stream.
How to further include. According to claim 1,
wherein the crude acetic acid product comprises less than or equal to 10 ppm lithium. According to claim 1,
separating the vapor product stream;
distilling the vapor product stream in a first distillation column and taking a sidedraw to obtain a distilled acetic acid product;
Distilling the distilled acetic acid product in a second distillation column to produce the crude acetic acid product containing acetic acid and lithium cations.
Including, how. According to claim 5,
adding a potassium salt selected from the group consisting of potassium acetate, potassium carbonate and potassium hydroxide to the distilled acetic acid product prior to distilling the distilled acetic acid product in a second distillation column, wherein at least a portion of the potassium is removed by a cation exchanger in acid form.
How to further include. According to claim 1,
contacting the crude acetic acid product with the cation exchanger at a temperature of 50°C to 120°C. According to claim 1,
contacting the intermediate acetic acid product with a metal-exchanged ion exchange resin at a temperature of 50° C. to 85° C. According to claim 1,
wherein the intermediate acetic acid product has a lithium ion concentration of less than 50 ppb. According to claim 1,
wherein the cation exchanger in acid form comprises a strong acid cation exchange macroreticular, macroporous or mesoporous resin in acid form. According to claim 1,
wherein the metal-exchanged ion exchange resin comprises at least 1% by weight of strong acid exchange sites occupied with silver. According to claim 1,
treating the purified acetic acid product with a cation exchange resin to recover any silver, mercury, palladium or rhodium.
How to further include. According to claim 1,
wherein the water concentration in the reaction medium is controlled to between 0.1 and 5 weight percent based on the total amount of reaction medium present. According to claim 1,
introducing a lithium compound selected from the group consisting of lithium acetate, lithium carboxylate, lithium carbonate, lithium hydroxide and mixtures thereof into the reactor to maintain the concentration of lithium acetate in the reaction medium between 0.3 and 0.7 weight percent;
How to further include. 15. The method of claim 14,
maintaining a hydrogen iodide concentration in the reaction medium between 0.1 and 1.3 weight percent;
maintaining a rhodium catalyst concentration in the reaction medium between 300 and 3000 wppm;
maintaining a water concentration in the reaction medium between 0.1 and 4.1 weight percent;
maintaining a methyl acetate concentration in the reaction medium between 0.6 and 4.1 weight percent; or
combination of these
How to further include. According to claim 1,
Controlling the butyl acetate concentration in the final acetic acid product to 10 wppm or less without directly removing the butyl acetate.
How to further include. According to claim 16,
the butyl acetate concentration maintains the acetaldehyde concentration in the reaction medium below 1500 ppm; Control the temperature of the reactor to 150 to 250 ° C; controlling the hydrogen partial pressure in the reactor to 0.3 to 2 atm; controlling the rhodium catalyst concentration in the reaction medium to 100 to 3000 wppm; or by combining them. According to claim 1,
controlling the ethyl iodide concentration in the reaction medium to 750 wppm or less;
How to further include. According to claim 18,
the propionic acid concentration in the final acetic acid product is less than 250 wppm without directly removing the propionic acid;
ethyl iodide in the reaction medium and propionic acid in the final acetic acid product are present in a weight ratio of 3:1 to 1:2;
Acetaldehyde and ethyl iodide are present in the reaction medium in a weight ratio of 2:1 to 20:1;
the ethanol concentration in the methanol feed into the reactor is less than 150 wppm; or
A combination of these methods. According to claim 19,
wherein the ethyl iodide concentration in the reaction medium is controlled by adjusting at least one of a hydrogen partial pressure in the carbonylation reactor, a methyl acetate concentration in the reaction medium, and a methyl iodide concentration in the reaction medium.

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