WO2001049647A1 - Procede de recuperation d'acide terephthalique purifie (pta) - Google Patents

Procede de recuperation d'acide terephthalique purifie (pta) Download PDF

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Publication number
WO2001049647A1
WO2001049647A1 PCT/IB2000/001898 IB0001898W WO0149647A1 WO 2001049647 A1 WO2001049647 A1 WO 2001049647A1 IB 0001898 W IB0001898 W IB 0001898W WO 0149647 A1 WO0149647 A1 WO 0149647A1
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WO
WIPO (PCT)
Prior art keywords
zone
pressure
letdown
solid portion
solid
Prior art date
Application number
PCT/IB2000/001898
Other languages
English (en)
Inventor
Luciano Piras
Sergio Schena
Michelle Chiarelli
Luigi Soro
Original Assignee
Inca International S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Inca International S.P.A. filed Critical Inca International S.P.A.
Priority to EP00979877A priority Critical patent/EP1250308A1/fr
Priority to US10/168,227 priority patent/US6639104B2/en
Priority to CA002395533A priority patent/CA2395533A1/fr
Priority to BR0016947-1A priority patent/BR0016947A/pt
Priority to JP2001550187A priority patent/JP2003519205A/ja
Priority to AU17254/01A priority patent/AU1725401A/en
Priority to KR1020027008475A priority patent/KR20020073157A/ko
Publication of WO2001049647A1 publication Critical patent/WO2001049647A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/47—Separation; Purification; Stabilisation; Use of additives by solid-liquid treatment; by chemisorption

Definitions

  • PROCESS FOR THE RECOVERY OF PURIFIED TEREPHTHALIC ACID PTA
  • the present invention relates to a new process for the production and recovery of purified terephthalic acid ("PTA"). More particularly, this application relates to the use of a rotary pressure filter to recover crystalline terephthalic acid and a process to recover the resulting crystals at atmospheric pressure.
  • the process involves moving the crystalline material through at least two valves defining separate zones, wherein each succeeding zone is at a pressure slightly less than the previous zone.
  • Terephthalic acid is used in the production of many different polymers, including polyethylene terephthalate (PET).
  • PET polyethylene terephthalate
  • the typical process for PET is the direct condensation of terephthalic acid with a polyalcohol. This direct esterification reaction requires purified terephthalic acid, for the reaction product to be acceptable.
  • Terephthalic Acid is produced by direct oxidation of p -xylene and subsequent crystallization from the mother liquor to recover the Crude Terephthalic Acid (CTA).
  • CTA Crude Terephthalic Acid
  • This CTA still contains approximately 0.2 ⁇ 0.4 percent by weight of 4-carboxybenzaldehyde (4- CBA) as major impurity.
  • 4-CBA 4-carboxybenzaldehyde
  • the CTA is typically dissolved in water and then the resulting solution is treated in a hydrogenation reactor, to convert the 4- CBA into p-toluic acid.
  • the solution from the hydrogenation reactor is then typically cooled by flash in a battery of crystallizers to precipitate the purified terephthalic acid (PTA) as a crystal.
  • PTA purified terephthalic acid
  • the slurry coming from the crystallizers still contains a significant amount of p-toluic acid that needs to be separated from PTA, to meet the usual commercial specification of no more that 150 ppm.
  • the traditional method to separate the PTA from its mother liquor consists in centrifuging the slurry at a temperature of from 100°C to 170°C and a pressure of from 1 to 7 bar. Under these conditions the majority of the p-toluic acid will remain in solution, allowing it to be separated.
  • the crystals of PTA coming from the centrifuges contain only a small amount of p- toluic acid, but do contain residual mother liquor (typically 1 O ⁇ l 5 percent).
  • the crystals are usually mixed with additional water, typically in a ratio of 1.1 to 1.5 m 3 water/ton PTA, to wash the mother liquor still entrained. This results in a slurry having a 45 ⁇ 5percent solids.
  • This slurry is then flashed to atmospheric pressure and fed either to a second stage of centrifuges or to Rotary Vacuum Filters (RVF).
  • the PTA, containing a residual 10 ⁇ 15 percent of water is then dried, typically in a rotary dryer, and stored.
  • the PTA crystals still contain minor amounts of p-toluic acid (usually less than 150 ppm) while 4-CBA content is typically lower than 25 ppm.
  • U.S. Patent 5,175,355 teaches a method of purifying the terephthalic acid comprising pressure filtering.
  • This reference teaches introducing an aqueous slurry (comprising purified terephthalic acid present as crystals and p-toluic acid present in the aqueous solution and as a co-crystallized form) into one or more filter cells.
  • the slurry is filtered at a system pressure of from atmosphere to 16 atm.
  • the filter cell with the resulting filter cake is then transported into a wash zone where a stream of water heated to 38°C to 205°C is introduced to the filter cell to form a reservoir of water over the filter cake.
  • Displacement washing is then achieved by forcing the water through the cake at a pressure gradient, which is at least 0.5 atm above the system pressure while maintaining the reservoir.
  • the displacement washing is allowed to continue for a sufficient time to remove a desired amount of impurities.
  • the filter cell is then transported to a pressure release zone wherein the system pressure is quickly released to flash evaporate the water remaining in the filter cake and the product is recovered.
  • the pressure release zone is then pressurized back up to the system pressure so as to be ready to accept additional product. This process reportedly results in terephthalic acid that contains less than 200 ppm by weight of p-toluic acid.
  • One aspect of the invention is a process for the preparation of purified terephthalic acid which comprises first introducing a liquid slurry containing crystallized terephthalic acid with impurities into a high pressure rotary filter, then filtering the slurry with the high- pressure rotary filter and collecting at least some of the solid portion. Then the solid portion is washed with additional amounts of water. The washed solid portion is then transferred to a letdown zone, which is at a pressure less than the zone in which the solid portion was collected. After the solid portion is transferred into the letdown zone, the connection between the letdown zone and the collection zone is sealed, such that a change of pressure in the letdown zone will not effect the pressure in the collection zone. The pressure of the letdown zone is then reduced and the solid removed. The letdown zone is then pressured back up so that it is ready to accept additional solid from the rotary filter. O 01/49647
  • the liquid slurry containing the terephthalic acid containing the impurities can come from any terephthalic acid production scheme. These are known in the art and are of minimal importance to the invention at hand.
  • the particular high-pressure rotary filter used to filter the slurry is similarly not critical to the present invention. Any filtering system capable of operating at a pressure greater than atmospheric pressure may be used. Preferably, for standard operating conditions, the filter is capable of handling the full throughput of terephthalic acid of the plant, and capable of operating under pressures of from 1.0 to 10.0 bar.
  • a suitable filter is the Bird Young Rotary Filter sold by Baker Process Inc.
  • the filter used in the apparatus of the present invention was a Bird Young Rotary Filter having a filtration area of 1 sq. ft and was able to process from 1 to 5 MT/h of solid PTA.
  • the filter typically consists of a case, pressurized at process pressure, and a drum covered by a filtering device such as a cloth or equivalent filtering device, pressurized at a pressure suitably lower than the case.
  • the drum is ideally divided into three zones: • First zone, where the mother liquor is removed.
  • the pressure of the case is preferably in a range of from 3 to 6.5 bar, with about 4.5 bar being most preferred.
  • the filtering is carried out at a temperature of from 133°C to 161°C, with 147°C being most preferred.
  • the pressure difference between case and drum is in the range of 0.1 to 2.0 bar, preferably in the range of 0.3 to 0.7 bar, most preferably 0.5 bar.
  • the mother liquor removed from the rotary pressure filter can be separately recovered and reused into the production process or sent to waste treatment facilities, as is known in the art.
  • the remaining solid portion is then washed with additional amounts of water. It has been discovered that less wash water is required in the present process to achieve purity similar to the traditional methods. Thus while any amount of water may be used in the washing stage of the present invention, it is preferred that less than 1 cubic meter per ton of PTA be used, in order to conserve water and reduce the energy associated to heating up this water to process temperature.
  • the water amount is preferably in a range of from 0.2 to 0.7 m 3 /MT of PTA, with about 0.5 m 3 /MT of PTA being most preferred.
  • the washing is preferably done at the same temperature as the filtering, although this is for convenience and is not mandatory.
  • the temperature of the water used to wash the solid material is in the range of 50°C to 161°C, preferably in the range of 130°C to 150°C, most preferably 147°C.
  • the wash liquor can then be separately collected from the mother liquor and reused into the production process or recycled back into the production process, as is known in the art.
  • the solid material is preferably collected in a collection zone and then passed into a let down zone, which is at a pressure that is less than the collection zone.
  • the collection zone is preferably separated from the letdown zone by a device of some sort, which can readily open and close to seal the letdown zone from the collection zone.
  • a device of some sort which can readily open and close to seal the letdown zone from the collection zone.
  • the letdown zone is at a pressure that is somewhat less than the collection zone.
  • this pressure difference is in the range of 0.01 to 0.3 bar, preferably in the range of 0.03 to 0.1 bar, most preferably 0.05 bar.
  • the device After the solid has moved into the letdown zone the device is closed, sealing off the letdown zone from the collection zone and/or rotary pressure filter. At this time the pressure is released. While flash evaporation can be used with the invention, it is preferred that the pressure be released more slowly. Ideally the pressure is released over a period from 0.5 to 10 seconds, more preferably from 4 to 7 seconds, although the optimal time will be a factor of the individual machinery and how fast the train is running.
  • the slow release of pressure can be achieved by many different methods. One way is just to have a narrow restriction in the vent line, which can be controlled. This can be used alone or in conjunction with a check valve, which maintains a certain pressure in the line (and therefore the letdown zone). Other methods such as bleed valves are well known in the art and can be used with
  • a second vent line without any restrictions can also be used as a double check to ensure that the letdown zone does not remain pressurized.
  • a second sealing device is opened and the solid contents are removed.
  • this transition is preferably conducted with a slight pressure differential so that when the sealing device is opened the contents are carried by gravity as well as the flow of gasses into the region of lesser pressure.
  • this pressure difference is in the range of 0.01 to 0.3 bar, preferably in the range of 0.03 to 0.1 bar, most preferably 0.05 bar.
  • any device capable of sealing the letdown zone can be used, however the Dome Valves are l o preferred.
  • the solid material can then be passed to a drier by mean of suitable device, such as a screw, for further processing as is known in the art.
  • the letdown zone When the contents have been removed from the letdown zone, the letdown zone is once again sealed off with the Dome Valve (or other suitable means) and then the letdown zone is pressured back up to a pressure suitable to accept more washed material.
  • the Dome Valve or other suitable means
  • the time it takes to release the pressure in the letdown zone, remove the product, and re- pressurize the letdown zone is calculated to correspond to the time it takes to fill up the collection zone, so that as soon as the letdown zone is emptied, sealed and re-pressurized, the collection zone is full, so that there is no down time in the cycle.
  • the letdown zone to be at the same pressure as the collection zone (or rotary
  • the letdown zone can be pressurized up to acceptable limits much more quickly. Thus the process can begin again almost immediately.
  • PLC Programmable Logic Controller

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

Abstract

L'invention concerne un procédé de préparation d'acide téréphtalique purifié, qui consiste à introduire dans un filtre rotatif haute pression une suspension liquide contenant de l'acide téréphtalique cristallisé comprenant des impuretés, puis à filtrer ladite suspension à l'aide dudit filtre rotatif haute pression et à collecter au moins une certaine quantité de la partie solide. Le filtre consiste généralement en un boîtier pressurisé à la pression du procédé et en un tambour recouvert par un dispositif de filtrage tel que, par exemple, un tissu ou un dispositif de filtrage équivalent, pressurisé à une pression appropriée inférieure à celle du boîtier. Le tambour est idéalement divisé en trois zones : la première zone de laquelle la solution-mère est enlevée ; la deuxième zone dans laquelle le solide est lavé et la troisième zone dans laquelle l'excédent de liqueur de lavage est enlevé et le solide est déchargé. La partie solide est lavée, sur le tambour de filtre, avec des quantités ajoutées d'eau. La partie solide lavée est ensuite transférée dans une zone de décharge, le raccord entre la zone de décharge et la zone de collecte étant fermé hermétiquement, de sorte qu'un changement de pression dans la zone de décharge ne modifie pas la pression dans la zone de collecte. La pression dans la zone de décharge est ensuite réduite progressivement et le solide est enlevé. La pression dans la zone de décharge est ensuite augmentée, de manière que ladite zone soit prête à accepter des solides supplémentaires en provenance du filtre rotatif.
PCT/IB2000/001898 1999-12-10 2000-11-30 Procede de recuperation d'acide terephthalique purifie (pta) WO2001049647A1 (fr)

Priority Applications (7)

Application Number Priority Date Filing Date Title
EP00979877A EP1250308A1 (fr) 1999-12-29 2000-11-30 Procede de recuperation d'acide terephthalique purifie (pta)
US10/168,227 US6639104B2 (en) 1999-12-10 2000-11-30 Process for the recovery of purified terephthalic acid (PTA)
CA002395533A CA2395533A1 (fr) 1999-12-29 2000-11-30 Procede de recuperation d'acide terephthalique purifie (pta)
BR0016947-1A BR0016947A (pt) 1999-12-29 2000-11-30 Processo para recuperar ácido tereftálico (tpa) purificado
JP2001550187A JP2003519205A (ja) 1999-12-29 2000-11-30 精製したテレフタル酸（ｐｔａ）の回収方法
AU17254/01A AU1725401A (en) 1999-12-29 2000-11-30 Process for the recovery of purified terephthalic acid (pta)
KR1020027008475A KR20020073157A (ko) 1999-12-29 2000-11-30 정제된 테레프탈산(ｐｔａ)의 회수 방법

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US17360799P 1999-12-29 1999-12-29
US60/173,607 1999-12-29

Publications (1)

Publication Number Publication Date
WO2001049647A1 true WO2001049647A1 (fr) 2001-07-12

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ID=22632791

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2000/001898 WO2001049647A1 (fr) 1999-12-10 2000-11-30 Procede de recuperation d'acide terephthalique purifie (pta)

Country Status (10)

Country Link
EP (1) EP1250308A1 (fr)
JP (1) JP2003519205A (fr)
KR (1) KR20020073157A (fr)
CN (1) CN1204107C (fr)
AU (1) AU1725401A (fr)
BR (1) BR0016947A (fr)
CA (1) CA2395533A1 (fr)
RU (1) RU2002120518A (fr)
SA (1) SA00210612B1 (fr)
WO (1) WO2001049647A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006005243A1 (fr) * 2004-07-08 2006-01-19 Action Perfect Engineering (Xiamen) Co., Ltd Procede de purification d'acide terephtalique
WO2007103068A1 (fr) * 2006-03-01 2007-09-13 Eastman Chemical Company Procédés et appareil d'isolation d'acide carboxylique
WO2009024872A2 (fr) * 2007-05-31 2009-02-26 Dow Italia S.R.L. Procédé amélioré de récupération d'acide téréphtalique
KR100976034B1 (ko) 2009-01-06 2010-08-17 삼성석유화학(주) 고순도의 테레프탈산 회수방법
US7847121B2 (en) 2006-03-01 2010-12-07 Eastman Chemical Company Carboxylic acid production process
US7863483B2 (en) 2006-03-01 2011-01-04 Eastman Chemical Company Carboxylic acid production process

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101318895B (zh) * 2007-06-08 2012-05-09 中国纺织工业设计院 一种分离提纯对苯二甲酸的新方法
CN103386227B (zh) * 2013-07-08 2015-05-27 嘉兴石化有限公司 精对苯二甲酸生产用转鼓式压力过滤机的改进方法
CN103585906B (zh) * 2013-11-25 2016-02-10 恒力石化（大连）有限公司 对苯二甲酸粉料回收装置及回收方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5175355A (en) * 1991-04-12 1992-12-29 Amoco Corporation Improved process for recovery of purified terephthalic acid
WO2000071226A1 (fr) * 1999-05-24 2000-11-30 Baker Hughes Incorporated Appareil de filtration sous pression et procede utilisant une chambre de depressurisation et materiau de transport

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5175355A (en) * 1991-04-12 1992-12-29 Amoco Corporation Improved process for recovery of purified terephthalic acid
WO2000071226A1 (fr) * 1999-05-24 2000-11-30 Baker Hughes Incorporated Appareil de filtration sous pression et procede utilisant une chambre de depressurisation et materiau de transport

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006005243A1 (fr) * 2004-07-08 2006-01-19 Action Perfect Engineering (Xiamen) Co., Ltd Procede de purification d'acide terephtalique
WO2007103068A1 (fr) * 2006-03-01 2007-09-13 Eastman Chemical Company Procédés et appareil d'isolation d'acide carboxylique
US7462736B2 (en) 2006-03-01 2008-12-09 Eastman Chemical Company Methods and apparatus for isolating carboxylic acid
US7847121B2 (en) 2006-03-01 2010-12-07 Eastman Chemical Company Carboxylic acid production process
US7863483B2 (en) 2006-03-01 2011-01-04 Eastman Chemical Company Carboxylic acid production process
WO2009024872A2 (fr) * 2007-05-31 2009-02-26 Dow Italia S.R.L. Procédé amélioré de récupération d'acide téréphtalique
WO2009024872A3 (fr) * 2007-05-31 2009-05-07 Dow Italia S R L Procédé amélioré de récupération d'acide téréphtalique
KR100976034B1 (ko) 2009-01-06 2010-08-17 삼성석유화학(주) 고순도의 테레프탈산 회수방법

Also Published As

Publication number Publication date
CN1414940A (zh) 2003-04-30
BR0016947A (pt) 2002-09-10
CA2395533A1 (fr) 2001-07-12
RU2002120518A (ru) 2004-01-10
SA00210612B1 (ar) 2006-06-04
CN1204107C (zh) 2005-06-01
AU1725401A (en) 2001-07-16
EP1250308A1 (fr) 2002-10-23
JP2003519205A (ja) 2003-06-17
KR20020073157A (ko) 2002-09-19

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