MXPA06008033A - Process for production of a dried carboxylic acid cake suitable for use in polyester production - Google Patents

Abstract

The present invention relates to a process by which a dried carboxylic acid cake is obtained from a slurry or cake carboxylic acid product through the use of at least one counter current wash. More specifically, the present invention relates to a process by which a dried terephthalic acid cake suitable as a starting material for polyester or co-polyester production is obtained from a slurry or cake terephthalic acid product through the use of at least one counter current wash.

Description

PROCESS FOR THE PRODUCTION OF A CONTAINED CARBOXYLIC ACID DRY CAKE FOR USE IN POLYESTE PRODUCTION TECHNICAL FIELD OF THE INVENTION This invention relates to a process by which a dried carboxylic acid cake is obtained from a mixture or product of carboxylic acid cake through the use of at least one countercurrent washing stream. More specifically, the present invention relates to a process by which a dry cake of terephthalic acid suitable as an initial material for the production of polyester or copolyester is obtained from a mixture or product of terephthalic acid cake through the use of at least one counter wash stream. BACKGROUND OF THE INVENTION In accordance with the objective of the manufacture of polyethylene terephthalate (PET) and other polyesters or copolyesters, a large part of the patent literature is devoted to describing the processes for the preparation of a dry carboxylic acid cake. suitable as starting material. In general, these inventions describe specific mixing schemes with a purified solid terephthalic acid and liquid ethylene glycol. Additionally, there is a substantial part of the literature devoted to the production of a purified terephthalic acid in the powder form that is suitable for use in the production of PET and other polyesters or co-polyesters. The aim of this invention is to describe a process by which the dry cake of carboxylic acid suitable as an initial material for the production of polyester or co-polyester is obtained from a mixture or product of carboxylic acid cake through the use of a reverse current zone of washing solvent. More specifically, the object of this invention is to describe a process by which a dry cake of terephthalic acid suitable as an initial material for the production of polyester or co-polyester is obtained from a mixture or product of terephthalic acid cake. through the use of a reverse current zone of washing solvent to reduce the amount of fresh solvent used in the process. Usually, the purified solid terephthalic acid is produced in a multiple stage process in which a crude terephthalic acid is produced. The liquid oxidation phase of p-xylene produces crude terephthalic acid. The crude terephthalic acid does not have sufficient quality for direct use as initial material in commercial PET. In contrast, crude terephthalic acid is usually refined to purify solid terephthalic acid. Usually in the terephthalic acid purification processes, the crude terephthalic acid is dissolved in water and hydrogenated for the purpose of conversion of 4-carboxybenzaldehyde to p-toluic acid, which is a more water-soluble derivative, and for the purpose of characteristically convert yellow compounds to colorless derivatives. The significant 4-carboxybenzaldehyde or p-toluic acid in the final product of purified terephthalic acid is particularly detrimental to polymerization processes in such a way that each can act as a dividing chain during the condensation reaction between terephthalic acid and ethylene glycol in PET production. Typical purified terephthalic acid contains at a basis weight less than 25 parts per million (ppm) of 4-carboxybenzaldehyde and less than 150 ppm of p-toluic acid. A number of other processes have been developed in which a convenient terephthalic acid as starting material for the production of commercial PET without the use of hydrogenation. Typically, terephthalic production processes involve catalyzed oxidation of p-xylene in an acetic acid solvent followed by filtration and drying of terephthalic acid. Typically, terephthalic acid (TPA) produced via catalyzed oxidation of p-xylene in an acetic acid solvent produces a mixture or cake product of terephthalic acid containing residual catalyst (eg cobalt)., manganese, and bromide compounds). In a common method of producing a substantially dry solid TPA from a terephthalic acid cake mixture or product, the terephthalic acid cake mixture or product is filtered to remove a substantial amount of liquid terephthalic acid from TPA solids. . The residual catalyst is usually separated from the terephthalic acid cake mixture or product by washing (rinsing) the wet cake with acetic acid free of catalyst, water or other solvent. The solid TPA is isolated by drying. In the present invention, a novel process has been discovered resulting in less solvent used than in the processes currently employed. In the conventional approach towards the production of terephthalic acid via catalyzed oxidation of p-xylene in an acetic acid solvent, a mixture or cake product of terephthalic acid is filtered, washed, then dried to produce a convenient terephthalic acid powder as the material 'Initial for PET production. In one embodiment of the present invention, the terephthalic acid cake mixture or product is filtered to produce a cake of terephthalic acid with solvent and a solvent stream of TPA mother liquor. The terephthalic acid-solvent cake is then washed (rinsed) with water to recover the residual metal catalyst material and to produce a terephthalic acid cake wet with water and a solvent / water TPA per liquor product. The water-wet terephthalic acid cake is then dried to produce a dry terephthalic acid cake suitable as starting material in a commercial PET process. In this embodiment of the invention at least one counter wash stream is used. By the use of a counter current zone of solvent washing the amount of solvent used can be substantially reduced as compared to a process without reverse current washing. In addition, the use of at least one counter wash stream can result in the reduction of equipment size and energy as compared to a TPA production process without a reverse wash stream. SUMMARY OF THE INVENTION The present invention relates to a process by which a dry carboxylic acid cake is obtained from a mixture or product of carboxylic acid cake. More specifically, the present invention relates to a process for the production of a dry cake of terephthalic acid convenient as a feed supply for the production of commercial PET. The resulting process uses less solvent than commonly used processes that do not use a reverse wash zone. It is an object of this invention to provide a process for the production of a dry carboxylic acid cake from a carboxylic acid cake mixture or product notwithstanding the use of at least one counter wash stream. It is another object of this invention to provide a process for the production of a dry cake of terephthalic acid from a mixture or cake product of terephthalic acid. It is another object of this invention to provide a process for producing a dry cake of terephthalic acid from a solvent mixture of terephthalic acid or cake by the use of a countercurrent zone of washing solvent. In a first embodiment of this invention, is to provide a process for producing a dry cake of carboxylic acid, the process comprises: (a) stirring in an impurity exchange liquor zone from a mixture of carboxylic acid to form a cake of wet carboxylic acid, a mother liquor stream, a solvent stream of mother liquor, and a solvent / water per liquor stream product; in which the solvent or water is added to the stream contrary to the flow of the carboxylic acid mixture; '(b) drying the wet carboxylic acid cake in water in a drying zone to form the dried carboxylic acid cake. In another embodiment of this invention, is to provide a process for producing a dry cake of carboxylic acid, the process comprising: (a) removing in a solvent zone of impurity liquor exchange from a mixture of carboxylic acid to form a cake of carboxylic acid with solvent, a mother liquor stream, and a mother liquor stream solvent; (b) adding water in a countercurrent water-wash zone to the carboxylic acid cake with solvent to produce a wet carboxylic acid cake in water and a solvent / water per liquor stream product; (c) drying the wet carboxylic acid cake in water in a drying zone to form the dried carboxylic acid cake. In another embodiment of this invention, a process for producing a dry carboxylic acid cake is provided, the process comprising: (a) removing in a solid-liquid separation zone impurities from a mixture of carboxylic acid to form a mixture or cake product and a mother liquor stream: (b) remove in a reverse current zone solvent liquor water residual impurities from the mixture or cake product to form a wet carboxylic acid cake in water, a stream mother liquor solvent, and one solvent / water per liquor stream product; and (c) drying the wet carboxylic acid cake in water in a drying zone to form the dried carboxylic acid cake. In another embodiment of this invention, a process for the production of a dry carboxylic acid cake is provided, the process comprising: (a) removing a solvent from a mixture or cake product in a solvent-water reverse current zone of liquor exchange; wherein a substantial portion of the solvent in the cake mixture or product is replaced with water to form a wet carboxylic acid cake in water; (b) drying the wet carboxylic acid cake in water in a drying zone to form the dried carboxylic acid cake. In another embodiment of this invention, a process for producing a dry cake of terephthalic acid is provided. the process comprises: (a) removing residual impurities from a terephthalic acid cake mixture or product to form a cake of terephthalic acid with acetic acid in a reverse current solvent zone; (b) removing a substantial portion of a solvent in a countercurrent wash zone from the terephthalic acid cake with acetic acid to form a wet terephthalic acid cake in water; and (c) drying the wet carboxylic acid cake in water in a drying zone to form the dried carboxylic acid cake. In another embodiment of this invention, a process for producing a dry terephthalic acid cake is provided, the process comprising: (a) removing a solvent from a terephthalic acid cake mixture or product in a reverse current exchange zone of solvent liquor-water; wherein a substantial portion of the solvent in the terephthalic acid cake mixture or product is replaced with water to form a wet terephthalic acid cake in water; (b) drying the wet terephthalic acid cake in water in a drying zone to form the dry cake of terephthalic acid. In another embodiment of this invention, a process for producing a dry cake of terephthalic acid is provided, the process comprising: (a) removing residual impurities from an acid cake mixture or product in a countercurrent solvent zone; terephthalic from a cake of terephthalic acid with acetic acid; wherein the countercurrent wash zone comprises at least one solid-liquid separation device that is operated at a temperature between 40 ° C to about 155 ° C; (b) removing a substantial portion of a solvent in a countercurrent wash zone from a cake of terephthalic acid with acetic acid to form a wet terephthalic acid cake in water; wherein the countercurrent wash water zone comprises at least one solid-liquid separation device which is operated at a temperature between 40 ° C to about 155 ° C; (c) drying the wet terephthalic acid cake in water in a drying zone to form the dry cake of terephthalic acid. In another embodiment of this invention, a process for producing a dry carboxylic acid cake is provided, the process comprising: (a) removing in a solid-liquid separation zone impurities from a mixture of carboxylic acid to form a mixture or cake product and a stream of mother liquor; (b) adding solvent to a cake mixture or product in a countercurrent zone of washing solvent to a cake mixture or product to produce a carboxylic acid cake with solvent and a solvent stream of mother liquor; (c) optionally adding water in a reverse flow zone to the carboxylic cake with solvent to produce a wet carboxylic acid cake in water and a solvent / water per liquor stream product; (d) drying the wet carboxylic acid cake in water in a drying zone to form the dry carboxylic acid cake. In another embodiment of this invention, a process for producing a dry cake of terephthalic acid is provided, the process comprising: (a) removing in a solid-liquid separation zone impurities from a mixture of terephthalic acid to form a mixture or cake product of terephthalic acid and a mother liquor stream; (b) adding solvent in a countercurrent zone of washing solvent to the terephthalic acid cake mixture or product to produce a cake of terephthalic acid with solvent and a solvent stream of mother liquor; (c) optionally, adding water in a countercurrent zone of wash water to the terephthalic acid cake with solvent to produce a terephthalic acid cake wet in water and a solvent / water per liquor stream product; (d) drying the wet carboxylic acid cake in water in a drying zone to form the dry carboxylic acid cake. These objectives, and other objectives, will be apparent to others with ordinary knowledge in the art of reading this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates one embodiment of this invention, a process for producing a dry carboxylic acid cake. Figure 2 illustrates another embodiment of this invention, a process for producing a dry carboxylic acid cake by use of a liquor exchange zone. Figure 3 illustrates another embodiment of this invention, a process for producing a dry carboxylic acid cake by using a reverse current zone of solvent-water liquor exchange. Figure 4 illustrates another embodiment of this invention, a process for producing a dry carboxylic acid cake by use of a liquor solvent exchange zone. DESCRIPTION OF THE INVENTION In one embodiment of this invention shown in Figure 1, a process for producing a dry carboxylic acid cake 170 is provided. The process comprises: Step (a) optionally comprises removing impurities from a carboxylic acid mixture 30 in a solid-liquid displacement zone 40 to form a mixture or product of carboxylic acid cake 70 and a stream of mother liquor 60; A mixture of carboxylic acid comprising at least one carboxylic acid, catalyst, at least one solvent, and impurities is introduced via lines not shown. The impurities typically comprise at least one or more of the following compounds: 4-carboxybenzaldehyde (4-CBA), trimellitic acid (TMA), and 2,6-dicarboxyfluorenone (2,6-DCF). Suitable solvents include, but are not limited to, aliphatic monocarboxylic acids, preferably containing from 2 to 6 carbon atoms, or benzoic acid and mixtures thereof and mixtures of these compounds with water. Preferably the solvent is acetic acid mixed with water, in a radius of about 5: 1 to about 99: 1, preferably between about 8.1 and up to about 49: 1. Throughout the specification of acetic acid will be referred to as the solvent. However, it can be appreciated that other suitable solvents, such as those previously disclosed, may also be used.

The typical solvent comprises acetic acid, but can be any solvent that has been previously mentioned. The carboxylic acid mixture can be produced by oxidizing an aromatic feed k in an oxidation zone. In one embodiment, the aromatic feed k comprises paraxylene. The oxidation zone comprises at least one oxidation reactor, and the carboxylic acid mixture comprises at least one carboxylic acid. The oxidation reactor may be operated at temperatures between about 120 ° C and about 250 ° C, preferably around 140 ° C to about 170 ° C. Typically the aromatic feed k comprises paraxylene and the carboxylic acid comprises terephthalic acid. In one embodiment of the invention - the oxidation zone comprises a bubble column. Thus, for example, when terephthalic acid is used, the mixture of carboxylic acid 30 can be referred to as a mixture of terephthalic acid and the dry cake of carboxylic acid 170 can be referred to as a dry cake of terephthalic acid. The carboxylic acids include any carboxylic acid produced via controlled oxidation of an organic precursor compound. For example, carboxylic acids include aromatic dicarboxylic acids preferably having from 8 to 14 carbon atoms, preferably aliphatic dicarboxylic acids having from 4 to 12 carbon atoms, or preferably cycloaliphatic dicarboxylic acids having from 8 to 12 atoms of carbon. Other examples of suitable carboxylic acids include, but are not limited to, terephthalic, benzoic, p-toluic acid, isophthalic acid, trimellitic acid, dicarboxylic acid naphthalene, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, diphenyl-3'-dicarboxylic acid, 2,2-dimethyl-1,3-propanediol dicarboxylic acid, succinic acid, glutamic acid, adipic acid, azelaic acid, sebacic acid, and mixtures thereof. The terephthalic acid mixture is conventionally synthesized via the liquid oxidation phase of paraxylene in the presence of convenient oxidation catalyst. The convenient catalyst includes, but is not limited to, cobalt, manganese and bromine compounds, which are soluble in the selected solvent. In one embodiment of the invention the catalyst comprises cobalt, bromine and manganese. The combined cobalt and manganese may be in concentrations of about 100 ppm to about 2700 ppm by weight in the liquor. The bromine may be in concentrations of about 1000 ppm to about 2500 ppm by weight in the liquor. The carboxylic acid mixture is fed to a solid-liquid displacement zone 40 capable of removing a portion of the liquid contained in the carboxylic acid mixture 30 to produce a mixture or product of carboxylic acid cake in conduit 70. The removal of a portion of the liquid to produce a mixture or product of carboxylic acid cake in conduit 70 can be achieved by any means known in the art. A portion of media of at least 5% by weight of the liquid is removed. Typically, the solid-liquid displacement zone 40 comprises a solid-liquid separator that is selected from the group consisting of a decanter centrifuge, rotary disk centrifuge, bell filter, vacuum rotary filter, and the like. The mixture of carboxylic acid in conduit 30 is fed to liquid solid displacement zone 40 comprising at least one solid-liquid separator. The solid-liquid separator (s) can be (are) operated at temperatures between about 50 ° C to about 200 ° C, preferably 140 ° C to about 170 ° C. The separator (s) can be operated at pressures between 0 psig to about 200 psig. The solid-liquid separator in the solid-liquid displacement zone 40 can be operated in continuous or batch mode, although it will be appreciated that for commercial processes, the continuous mode is preferred. The impurities are displaced from the solid-liquid displacement zone 40 within a mother liquor stream and withdrawn via line 60. In one embodiment of the invention, the additional solvent is fed to the solid-liquid displacement zone. via line 50 for remixing the carboxylic acid mixture 30 and forming a mixture or product of carboxylic acid cake 70. When a mixture of terephthalic acid is used in the solid-liquid separation zone 40, a cake mixture or product is produced of terephthalic acid. The terephthalic acid cake mixture or product typically comprises terephthalic acid and acetic acid. The mother liquor 60 is removed from the solid-liquid displacement zone 40 via line 60 and comprises a solvent, typically acetic acid, catalyst, and bromine compounds. The mother liquor in line 60 can be sent to a process for separation of impurities from the oxidation solvent via lines not shown or recycled to the catalyst system via lines not shown. A technique for removing impurities from mother liquor commonly used in the chemical processing industry is to remove or "purge" some portion of the recycled stream. Typically, the purge stream is simply disposed of or, if economically justified, subjected to various treatments to remove unwanted impurities while recovering valuable components. Examples of impurity removal processes include U.S. Patent 4,939,297 and U.S. Patent 4,356,319, incorporated herein by reference. Step (b) comprises the removal in a countercurrent zone of wash solvent of 80 residual impurities from a mixture or product of carboxylic acid cake 70 to form a carboxylic acid cake with solvent 110 and a solvent of stream of mother liquor 100. The line 7Ó contains a mixture or product of carboxylic acid cake 70 comprising a carboxylic acid, residual impurities and a solvent. The residual impurities comprise residual catalyst (typically but not limited to cobalt, manganese, or bromine). Suitable solvents include, but are not limited to, aliphatic monocarboxylic acids, preferably containing from 2 to 6 atoms, or benzoic acid and mixtures thereof and mixtures of these compounds with water. Preferably, the solvent is comprised mainly of acetic acid and / or some water.

The radius of acetic acid to water can be in the range from 50:50 to 99: 1 acetic acid to water per mass, more preferably in the range of 85:15 to 98: 2, and more preferably in the range of 90:10 to 97: 3. Suitable carboxylic acids included but not limited to terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid, and mixtures thereof. The mixture or product of carboxylic acid cake 70 is in the range of 10 to 90% by weight of carboxylic acid. Preferably the mixture or product of carboxylic acid cake 70 is in the range of 25-40% by weight of carboxylic acid for a mixture and in the range of 70-90% by weight for the cake product. More preferably, the mixture or product of carboxylic acid cake 70 is in the range of 30-40% by weight of carboxylic acid. The mixture or product of carboxylic acid cake in conduit 70 is then introduced into a countercurrent zone of washing solvent 80, in which a substantial portion of the solvent is recovered in the solvent stream of mother liquor in. the conduit 100. The mother liquor solvent 102 comprises a substantial portion of the solvent. The additional solvent may be added via a conduit 90 contrary to the flow of the mixture or product of carboxylic acid cake 70 in the reverse current zone of washing solvent 80. The number of steps of the reverse stream of washing may be any amount of steps necessary to produce the carboxylic cake with the solvent at the desired purity. Typically, the number of steps in the counter wash stream may be about 1 to about 8, preferably about 2 to about 6, most preferably about 2 to about 4. For washing with more than one stage, the opposite current flow is preferable. The reverse solvent wash zone 80 comprises at least one liquid solid separating device capable of efficiently separating solids and liquids. The solid-liquid separation device can typically be comprised of, but not limited to, the following types of devices: centrifuges, cyclones, rotary drum filters, bell filters, pressure filters, etc. The reverse solvent wash zone 80 comprises at least one solid-liquid separation device 110 which can operate without a temperature range of from about 40CC to 115 ° C. Preferably the solid-liquid separation device 110 can operate within a temperature range of from about 80 ° C to about 150 ° C. More preferably, the liquid solid separation device 110 can operate within a temperature range of from about 90 ° C to about 150 ° C. A carboxylic acid cake with solvent 110, is produced in which the moisture composition of the carboxylic acid cake with solvent 110 can be in the range of 0. 5-30% by moisture weight, preferably in the range of 1- 20% moisture, more preferably in the range of 1-10% moisture. Optionally, the residual solvent can be removed by a gas displacement step to minimize solvent contamination with washing. When the carboxylic acid is terephthalic acid and the solvent is acetic acid, a cake of terephthalic acid with acetic acid is produced.

Step (c) optionally comprises removing a substantial portion of a solvent in a countercurrent wash zone 120 from the carboxylic acid cake with solvent 110 to form an acidic cake of wet carboxylic acid in water 100 and one solvent / water per liquor stream product 140.

The carboxylic acid cake with solvent 110 is then subjected to washing or "rinsing" with water or substantially water with residual amounts of solvent in the counter current zone of wash water 120, in which a substantial portion of the solvent is replaced with water to form a wet carboxylic acid cake in water 150. The wetted carboxylic acid cake in water 150, it is preferably in the range of about 0.5% to about 30% moisture, more preferably in the range of about 1% to about 20% moisture, and most preferably in the range of about 1%. % up to around 10% humidity. The residual moisture of the wet carboxylic acid cake in water 150 may contain less than about 2% solvent in a dough base. Additionally, the wet carboxylic acid cake in water 150 should contain less than 1% of any metal, preferably less than 10 ppm by weight, typically used as a catalyst in the oxidation of p-xylene, in the cake mix or cake product. carboxylic acid in line 70, must remain in the wet carboxylic acid cake in water 150. Examples of metals include but are not limited to cobalt, and manganese. - The washing water is introduced into the reverse flow zone of washing water 120 via line 130. The washing water must be, in a continuous base, comprising a proportion of feed mass in the radius with the solids in the carboxylic acid cake with solvent 110 in the range of about 0.1: 1 to about 1.5: 1, preferably in the range of about 0.1: 1 to about 0.6: 1, most preferably in the range of about 0.2: 1 to about 0.4: 1. There are no limitations on the temperature or pressure of the wash water including the use of vaporized water, steam, or a combination of water and steam, as a wash. In one embodiment of the invention, the wash water is introduced to the opposite stream of the carboxylic acid cake with solvent. Additional wash water can be added via stream conduit 130 contrary to the flow of the carboxylic acid cake with solvent 110 in the reverse stream zone of wash water 120. The amount of countercurrent steps of wash water can be any amount of steps necessary to produce the wet carboxylic acid cake in water at the desired purity. Typically, the number of steps in the reverse stream of wash water can be about 1 to about 8, preferably about 2 to about 6, most preferably about 2 to about 4. The reverse current zone of washing water comprises a solid-liquid separation device 120 which can typically be comprised of, but not limited to, the following types of devices: centrifuge, cyclones, rotary drum filters, bell filters, pressure filters, etc. The solid-liquid separation device can be operated within a temperature range of from about 40 ° C to about 155 ° C. Preferably, the second solid-liquid separation device can operate within a temperature range of from about 80 ° C to about 150 ° C. More preferably, the second solid-liquid separation device can operate within a temperature range of from about 90 ° to about 150 ° C. Optionally, the solvent / water per liquor product from the reverse stream zone of wash water 120, is secreted from the solvent stream of mother liquor produced by the reverse flow zone of wash solvent 80. The step (d) ) comprises drying the wet carboxylic acid cake in water 150 in a drying zone 160 to produce a dry product of carboxylic acid 170. The wetted carboxylic acid cake in water 150 is removed from the reverse stream of wash water 120 or the counter current zone of wash solvent 80 and fed to drying zone 160. A portion of the solvent or water and remaining catalyst and remaining impurities is separated, and the dried carboxylic acid cake is removed via line 170. The drying zone 160 comprises a convenient filter for recovering the solid carboxylic acid and a dryer. The filtration can be carried out by any means known in the art. For example, a rotary vacuum filter can be used by the filtration to produce a filter cake. The filter cake is taken through an initial stage of solvent removal, then rinsed with washing acid to remove residual catalyst, and the solvent can be removed again before being sent to the dryers. The drying of the filter cake can be carried out by any means known in the art which is capable of evaporating at least 10% of the remaining volatiles in the filter cake to produce the carboxylic acid product. For example, a Single Shaft Porcupine® Processor dryer can be used. In other embodiments of this invention, step (a), step (b) and step (c) can be combined within an area known as liquor exchange zone 250 as shown in figure 2. The exchange zone of liqueur 250 comprises at least one solid-liquid separation device capable of developing the combined function of the liquid solid separation zone 40, the washing reverse current zone 80 and the counter current zone of washing water 120 as previously described. he described. Step (b) and step (c) may also be combined within an area known as the solvent-water counter exchange zone of liquor 260 as shown in Figure 3. Finally the stage (a) and step (b) can be combined within an area known as the solvent liquor exchange zone 270 as shown in Figure 4. In each of the above embodiments at least one separation device is comprised. solid-liquid capable of developing the functions of the combined zones as previously described. Examples of devices that can be used in the exchange zone of - Liquor 250, or solvent-water exchange liquor zone 260, or the zone of solvent exchange liquor 270 including but not limited to, the following types of centrifugal devices, cyclones, filters, and the like or combinations thereof.

Claims (47)

1. CLAIMS 1.- A process for producing a dry carboxylic acid cake, characterized in that it comprises: (a) removing impurities from a mixture of carboxylic acid to form a cake in a liquor exchange zone, of wet carboxylic acid in water , a mother liquor stream, a solvent stream of mother liquor, and a solvent / water per liquor stream product; in which solvent or water is added to the stream contrary to the flow of this carboxylic acid mixture; (b) drying this wet carboxylic acid cake in water or carboxylic acid cake with solvent in a drying zone to form this dry carboxylic acid cake.
2. 2. The process according to claim 1, characterized in that the liquor exchange zone comprises from about 2 to about 4 stages of water or washings of reverse current solvent.
3. 3. The process according to claim 1, characterized in that the solvent and water is added to the current contrary to the flow of this carboxylic acid mixture.
4. 4. A process according to claim 1, characterized in that the carboxylic acid is selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid, and mixtures thereof.
5. 5. A process according to claim 1, characterized in that the carboxylic acid is terephthalic acid.
6. 6. A process according to claim 1, 2 or 3 characterized in that the drying zone evaporates at least 10% volatiles in the wet carboxylic acid cake in water.
7. 7. A process according to claim 1, characterized in that the crude mixture of carboxylic acid comprises terephthalic acid, catalyst, acetic acid, and impurities is removed at a temperature of between about 110 ° C to about 200 ° C at from an oxidation zone.
8. 8. A process for producing a dry carboxylic acid cake, characterized in that it comprises: (a) removing impurities from a carboxylic acid mixture in a solvent zone to form a carboxylic acid cake with solvent, a mother liquor stream, and a solvent stream of mother liquor; (b) optionally, adding water in a countercurrent zone of wash water - to this carboxylic acid cake - with solvent to produce a wet carboxylic acid cake in water and a solvent / water per liquor stream product; (c) drying this wet carboxylic acid cake in water or this carboxylic acid cake with solvent in a drying zone to form this dry carboxylic acid cake.
9. 9. A process according to claim 8 characterized in that the carboxylic acid is selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid, and mixtures thereof.
10. 10. A process according to claim 8 characterized in that this carboxylic acid is terephthalic acid.
11. 11. A process according to claim 8 or 9 characterized in that this drying zone evaporates at least 10% volatiles in this wet carboxylic acid cake in water.
12. 12. - A process according to claim 8 characterized in that this mixture of crude carboxylic acid comprising terephthalic acid, catalyst, acetic acid, and impurities is removed at a temperature between about 110 ° C to about 200 ° C from from an oxidation zone.
13. 13. A process for producing a dry carboxylic acid cake, characterized in that it comprises: (a) stirring in a solid-liquid impurity separation zone of a carboxylic acid mixture to form a cake mixture or product, and a stream of mother liquor; (b) removing residual impurities from this mixture or cake product in a reverse current zone of solvent-liquor exchange water to form a wet carboxylic acid cake in water, a solvent stream of mother liquor, and a solvent / water per liquor stream product; (c) drying this wet carboxylic acid cake in water or carboxylic acid cake with solvent in a drying zone to form this dry carboxylic acid cake.
14. 14. A process according to claim 13 characterized in that the carboxylic acid is selected from a group, consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid and mixtures thereof.
15. 15. A process according to claim 13 characterized in that the carboxylic acid is terephthalic acid.
16. 16. A process according to claim 13 characterized in that the mixture of crude carboxylic acid comprising terephthalic acid, catalyst, acetic acid, and impurities is removed at a temperature between about 110 ° C to about 200 ° C at from an oxidation zone.
17. 17. A process according to claim 13 or 14, characterized in that the drying zone evaporates at least 10% volatiles in this wet carboxylic acid cake in water.
18. 18. A process for producing a dry carboxylic acid cake, characterized in that it comprises the steps of: (a) removing a solvent from a cake product mixture in a countercurrent zone of solvent-liquor exchange water; wherein a substantial portion of the solvent in this cake mixture or product is replaced with water to form a wet carboxylic acid cake in water; (b) drying this wet carboxylic acid cake in water or this carboxylic acid cake with solvent in a drying zone to form this dry carboxylic acid cake.
19. 19. A process according to claim 18 characterized in that the carboxylic acid is selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid and mixtures thereof.
20. 20. A process according to claim 18 characterized in that the carboxylic acid is terephthalic acid.
21. 21. A process according to claim 19 characterized in that the crude mixture of carboxylic acid comprising terephthalic acid, catalyst, acetic acid, and impurities is removed at a temperature between about 110 ° C to around 200 ° C from an oxidation zone.
22. 22. A process according to claim 18 or 19, characterized in that the drying zone evaporates at least 10% volatiles in this wet carboxylic acid cake in water.
23. 23. A process for producing a dry cake of terephthalic acid, characterized in that it comprises the following steps: (a) removing residual impurities from a mixture or terephthalic acid cake product in a reverse current zone of wash solvent. forming a cake of terephthalic acid with acetic acid; (b) optionally, removing a substantial portion of a solvent in a countercurrent zone of wash water from this terephthalic acid cake with acetic acid to form a wet terephthalic acid cake in water; and (c) drying this wet carboxylic acid cake in water. or this carboxylic acid cake with solvent in a drying zone to form this dry carboxylic acid cake.
24. 24: - A process according to claim 23 characterized in that this reverse current zone of washing solvent comprises a solid-liquid separation device that is operated at a temperature between about 40 ° C to about 155 ° C.
25. 25. A process according to claim 24 characterized in that this carboxylic acid is terephthalic acid.
26. 26. A process according to claim 23, 24 or 25, characterized in that the drying zone evaporates at least 10% of volatiles in the dry cake of wet carboxylic acid in water.
27. 27. A process according to claim 22 characterized in that the mixture of crude carboxylic acid comprises terephthalic acid, catalyst, acetic acid, and impurities is removed at a temperature between about 110 ° C and about 200 ° C from an area of oxidation.
28. 28.- A process for producing a dry cake of terephthalic acid, characterized in that it comprises: (a) removing a solvent from a terephthalic acid cake mixture or product in an area of opposite flow of solvent-liquor exchange water; wherein a substantial portion of the solvent in this terephthalic acid cake mixture or product is replaced with water to form a wet terephthalic acid cake in water; (b) drying this cake of wet terephthalic acid in water or this cake of terephthalic acid with solvent in. a drying zone to form this dry cake of terephthalic acid.
29. 29. A process according to claim 28, characterized in that the zone of liquor exchange solvent comprises a solid-liquid separation device that is operated at a temperature between about 40 ° C to about 155 ° C.
30. 30. A process according to claim 28, characterized in that the drying zone evaporates at least 10% volatiles in the wet carboxylic acid cake in water.
31. 31. A process according to claim 29, characterized in that the drying zone evaporates at least 10% of volatiles in the wet carboxylic acid cake in water.
32. 32. - A process according to claim 29, characterized in that the crude mixture of carboxylic acid comprising terephthalic acid, catalyst, acetic acid, and impurities is removed at a temperature between about 110 ° C and about 200 ° C from an area of oxidation.
33. 33.- A process for producing a dry cake of terephthalic acid, characterized in that it comprises: (a) removing residual impurities from a mixture or cake product of terephthalic acid in a reverse current zone of wash solvent. cake of terephthalic acid with acetic acid; wherein the countercurrent wash zone comprises at least one solid-liquid separation device which is operated at a temperature between 40 ° C to about 155 ° C; (b) optionally, removing a substantial portion of a solvent in a countercurrent zone of wash water from the carboxylic acid cake with acetic acid to form a terephthalic acid cake wet in water, in which the zone of counter current of wash water comprises at least one solid-liquid separation device which is operated at a temperature between about 40 ° C to about 155 ° C; (c) drying the wet terephthalic acid cake in water or the terephthalic acid cake with solvent in a dry zone to form the dry cake of terephthalic acid.
34. 34. - A process for producing a dry carboxylic acid cake, characterized in that it comprises: (a) removing a solid-liquid impurity separation zone from a carboxylic acid mixture to form a cake mixture or product and a mother liquor stream; (b) adding solvent to a cake mixture or product in a countercurrent zone of washing solvent to this mixture or cake product to produce a carboxylic acid cake with solvent and a solvent stream of mother liquor; (c) optionally, adding water in a countercurrent zone of wash water to the carboxylic acid cake with solvent to produce a wet carboxylic acid cake in water and solvent / water per liquor product stream. (d) drying the wet carboxylic acid cake in water or the carboxylic acid cake with solvent in a drying zone to form the carboxylic acid cake.
35. 35. A process according to claim 34, characterized in that the carboxylic acid is selected from a group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid and mixtures thereof.
36. 36.- A process according to claim 34 characterized in that the carboxylic acid is terephthalic acid ..
37. 37.- A process according to claim 34 or 35 characterized in that the drying zone evaporates at least 10% volatiles in the cake of wet carboxylic acid in water.
38. 38.- A process according to claim 34, characterized in that the crude carboxylic acid is removed at a temperature between about 110 ° C and about 200 ° C. of the oxidation zone.
39. 39. A process for producing a dry cake of terephthalic acid, characterized in that it comprises: (a) removing impurities from the terephthalic acid mixture in the solid-liquid separation zone to form a mixture or cake product and a liquor stream mother; (b) adding solvent in a counter area of wash solvent stream to the terephthalic acid cake mixture or product to produce a cake of terephthalic acid with solvent and a solvent stream of mother liquor; (c) optionally, adding water in the countercurrent zone of wash water to the terephthalic acid cake with solvent to produce a cake of wet terephthalic acid in water with solvent and a solvent / water per stream of liquor product; (d) drying the wet terephthalic acid cake in water or the terephthalic acid cake with solvent in a drying zone to form the dried carboxylic acid cake.
40. 40. A process according to claim 39 characterized in that the reverse current zone of washing solvent comprises a solid-liquid separation device that is operated at a temperature between about 40 ° C to about 155 ° C.
41. 41. A process according to claim 40 characterized in that the counter current zone of washing water comprising a solid-liquid separation device that is operated at a temperature between about 40 ° C to about 155 ° C.
42. 42. A process according to claim 39, characterized in that the carboxylic acid is terephthalic acid.
43. 43.- A process according to claim 39 or 40, characterized in that the drying zone evaporates at least 10% volatiles in the wet carboxylic acid cake in water.
44. 44.- A process according to claim 39, characterized in that the mixture of carboxylic acid comprising terephthalic acid, catalyst, acetic acid, and impurities is removed at a temperature between about 110 ° C and about 200 ° C in the area of oxidation.
45. 45.- A process according to claim 39, characterized in that the countercurrent zone of washing water comprises from about 2 to about 4 stages of water of contrary flow of washings.
46. 46. A process according to claim 39, characterized in that the reverse current zone of the washing solvent comprises from about 2 to about 4 stages of solvent of reverse current of washings.
47. 47. A process according to claim 45, characterized in that the washing countercurrent zone comprises around 2 to about 4 stages of reverse current solvent of washings.