Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
  • C07C51/255—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting
  • C07C51/265—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting having alkyl side chains which are oxidised to carboxyl groups
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

• 4-CBA in the case of terephthalic acid can be readily oxidised to the desired aromatic carboxylic acid which is soluble in the supercritical or near supercritical fluid thereby allowing a significant reduction in contamination of the recovered aromatic carboxylic acid product with the aldehyde intermediate.
• the terephthalic acid is only sparingly soluble in the aliphatic carboxylic acid solvent, and it precipitates in the course of the reaction; because the conversion of 4-CBA to terephthalic acid proceeds relatively slowly, 4-CBA, therefore, tends to co-precipitate with the terephthalic acid, both during the reaction and during the subsequent recovery of the terephthalic acid.
• the pressure and temperature of the process are selected to secure supercritical or near supercritical conditions.
• operating temperatures are typically in the range of from 300° to 480°C, more preferably 330° to 450°C, typically from a lower limit of about 350° to 370°C to an upper limit of about 370° to about 420°C.
• Operating pressures are typically in the range from about 40 to 350 bara, preferably 60 to 300 bara, more preferably 220 to 280 bara, and particularly 250 to 270 bara.
• near supercritical conditions we mean that the reactants and the solvent constitute a substantially single homogeneous phase; in practice, this can be achieved under conditions below the critical temperature for water.
• the term “near supercritical conditions” means that the solvent is at a temperature which is not less than 50°C below, preferably not less than 35°C below, more preferably not less than 20°C below the critical temperature of water at 220.9 bara.
• the catalyst may be in the form of mobile pellets, particles, finely divided form, metal sponge form or the like with means being provided if necessary to confine the same to the reaction zone so that, in operation, the catalyst pellets etc become suspended or immersed in the reaction medium flowing through the reaction zone.
• the use of a heterogeneous catalyst in any of these ways confers the advantage of being able to confine the catalysis effect to a well-defined zone so that, once the reaction medium has traversed the zone, further oxidation takes place at a reduced rate or may be significantly suppressed.
• the reaction mixture After traversing the continuous flow reactor, the reaction mixture comprises a solution of aromatic carboxylic acid.
• the solution may also contain catalyst (if used), and relatively small quantities of by-products such as intermediates (e.g. p-toluic acid and 4-CBA in the case of terephthalic acid), decarboxylation products such as benzoic acid and degradation products such as trimellitic anhydride and any excess reactants.
• the desired product, aromatic carboxylic acid, such as terephthalic acid may be recovered by causing or allowing the aromatic carboxylic acid to crystallise from the solution in one or more stages followed by a solids-liquid separation in one or more stages.
• Another aspect of the invention is concerned with cooling of the product stream resulting from the oxidation reaction.
• the product stream is subjected to a solids-liquid separation to recover the aromatic carboxylic acid and the mother liquor (which may but need not necessarily contain dissolved catalyst components) is recycled to the oxidation reaction zone.
• Figure 3 is a schematic flowsheet illustrating in more detail an arrangement wherein the precursor is added to a premixed stream of oxygen and water (i.e. an arrangement according to the process illustrated in Figure 1 A or IB).
• water stream W would also contain the catalyst; in a process using heterogeneous catalysts, the catalysts would be present inside pipe P.
• the stream passes through the reactor pipe P and at a series of locations spaced at intervals along the length of the pipe P, preheated and compressed oxygen dissolved in supercritical or near supercritical water is supplied via injection passages A to E to produce a product stream S comprising terephthalic acid in supercritical or near supercritical aqueous solution.
• thermocouple the aluminium block heaters of preheater 152 and reactor 156 also contain thermocouples, not shown.
• the O 2 compressor, dosage unit, preheater and reactor were obtained from NWA GmbH; the pumps were Gilson 302, 305, 306 and 303; the back-pressure regulator obtained from Tescom (model 26-1722-24-090).

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

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• 2001
  • 2001-07-13 US US09/905,094 patent/US6765113B2/en not_active Expired - Fee Related
  • 2001-07-17 BR BRPI0112990-2A patent/BR0112990B1/pt not_active IP Right Cessation
  • 2001-07-17 JP JP2002512108A patent/JP2004504289A/ja active Pending
  • 2001-07-17 AU AU2001275960A patent/AU2001275960A1/en not_active Abandoned
  • 2001-07-17 AT AT01953518T patent/ATE400543T1/de not_active IP Right Cessation
  • 2001-07-17 WO PCT/US2001/022474 patent/WO2002006201A1/en not_active Ceased
  • 2001-07-17 ES ES01953518T patent/ES2309080T3/es not_active Expired - Lifetime
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• 2002
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• 2004
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