Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/42—Separation; Purification; Stabilisation; Use of additives
  • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
  • C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
• • 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
  • C07C51/25—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of unsaturated compounds containing no six-membered aromatic ring
  • C07C51/252—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of unsaturated compounds containing no six-membered aromatic ring of propene, butenes, acrolein or methacrolein
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds

Definitions

• the present invention relates to a process for the production of acrylic acid, in which a gaseous reaction mixture obtained in the gas phase oxidation for the production of acrylic acid, which contains acrylic acid, is cooled by means of an inert high-boiling solvent, and a gaseous mixture containing acrylic acid is obtained. Furthermore, it relates very generally to the use of an inert high-boiling solvent for cooling a gaseous reaction mixture obtained in the gas phase oxidation for the production of acrylic acid, and to a process for the production of acrylic acid esters.
• the acrylic acid contained is removed as crude acrylic acid via a side draw from the column.
• the high boilers e.g. oligomeric acrylic acid are obtained in the bottom of the column.
• the crude acrylic acid so obtained generally contains from about 0.1 to about 2% by weight of acetic acid and from about 0.5 to about 3% water.
• there are other high boilers in the swamp e.g. Contain residues of the inert high-boiling solvent and stabilizers.
• the process is advantageously carried out as shown in the figure and as described below is, the column can be divided into different sections in which different procedural tasks are solved.
• the reference numerals in the figure designate the individual sections in the column (I.a to I.f) or separate sections / apparatuses in front of the column (E), feed and discharge lines (1-12) and the cooling circuits II and LTJ.
• the gaseous mixture is introduced into the device E and cooled. This can be done via indirect cooling, with an inert high-boiling solvent (LM) as the cooling medium, which can be supplied via the feed line (12).
• LM inert high-boiling solvent
• the desired target component acrylic acid is used as raw acrylic acid e.g. discharged in liquid form via a collecting tray and partly passed as reflux (R) below the side take-off 7 via a heat exchanger (WT) and returned to the column.
• R reflux
• WT heat exchanger
• the gas is preferably returned as cycle gas via line 11 to the acrylic acid production.
• the low boilers obtained after the separation that is to say essentially water and acetic acid, are wholly or partially returned to the upper part of the separation device after being discharged from the separation device, optionally with the addition of a polymerization inhibitor, in order to condense the gaseous mixture contained in the acrylic acid there to facilitate contained low boilers.
• the present invention also relates to a process for the preparation of an acrylic acid ester or a mixture of two or more thereof, which comprises a further step C in addition to the steps A and B defined above:
• the crude acrylic acid is esterified directly with a C r C 12 , preferably C r C 10 alkanol, in particular C 4 -C 8 alkanol.
• Alkanol acrylic acid ratio: 1: 0.7-1.2 (molar)
• Catalyst sulfuric acid or a sulfonic acid such as e.g. p-toluenesulfonic acid
• Reaction temperature About 80-160 ° C, preferably about 90-130 ° C - 18 -
• an esterification mixture is obtained which comprises the desired acrylic acid ester (s) and also the corresponding acetic acid ester.
• the acrylic acid esters are isolated in a conventional manner. As a rule, the catalyst and the unreacted acrylic acid are first washed out and then the esterification mixture is separated, preferably separated by distillation.
• the low boiler fraction resulting from the separation by distillation which mainly consists of alkanol (approximately 20 to approximately 70%), acetic acid ester (approximately 5 to approximately 40%) and acrylic acid ester (approximately 5 to approximately 50%), is optionally combined with that in the Pure distillation of the desired ester distillation bottoms, which among other things Contains diacrylic acid esters, alkoxypropionic acid esters and oligomeric and polymeric acrylic acid esters, with a 5 to 40 wt. -% aqueous alkali, preferably NaOH treated at boiling temperature for about 30 minutes to about 10 hours.
• the reaction with alkali metal hydroxide solution can be carried out continuously or batchwise, without pressure or under overpressure or underpressure.
• a stirred or tubular reactor is preferably used for this.
• Low-water raw acrylic acid is technically easy to obtain. Only one separation device, preferably a distillation column, is required.
• This gaseous reaction mixture was cooled to 140 ° C. in a spray cooler (quench) by injecting a eutectic mixture of diphenyl and diphenyl ether (0.5 mVm 3 ).
• the crude acrylic acid was circulated through a heat exchanger and a temperature of 95 ° C. was set.
• Droplet separator (cyclone) passed into the lower part of a distillation column with 60 dual-flow trays, a side draw between the 15th and 16th trays - 22 -
• the distillate obtained in the spray condenser which mainly consisted of water and acetic acid, was re-applied to the uppermost column bottom after 20% had been removed and 500 ppm of hydroquinone had been added as reflux.

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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)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7863098

Family Applications (1)

Country Status (8)

Cited By (7)

Families Citing this family (14)

Citations (5)

Family Cites Families (9)

• 1998
  • 1998-03-31 DE DE19814375A patent/DE19814375A1/de not_active Withdrawn
• 1999
  • 1999-03-24 EP EP99913295A patent/EP1066240B1/de not_active Expired - Lifetime
  • 1999-03-24 JP JP2000541130A patent/JP4410935B2/ja not_active Expired - Fee Related
  • 1999-03-24 BR BR9909355-3A patent/BR9909355A/pt not_active Application Discontinuation
  • 1999-03-24 CN CNB998046744A patent/CN1133614C/zh not_active Expired - Fee Related
  • 1999-03-24 US US09/646,751 patent/US6555707B1/en not_active Expired - Fee Related
  • 1999-03-24 DE DE59900932T patent/DE59900932D1/de not_active Expired - Fee Related
  • 1999-03-24 WO PCT/EP1999/001998 patent/WO1999050220A1/de not_active Ceased
  • 1999-03-31 MY MYPI99001219A patent/MY120799A/en unknown

Patent Citations (5)

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