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
  • C07C51/445—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation by steam distillation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J14/00—Chemical processes in general for reacting liquids with liquids; Apparatus specially adapted therefor
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/09—Preparation of carboxylic acids or their salts, halides or anhydrides from carboxylic acid esters or lactones
• • 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
  • C07C51/42—Separation; Purification; Stabilisation; Use of additives
  • C07C51/48—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00002—Chemical plants
  • B01J2219/00004—Scale aspects
  • B01J2219/00006—Large-scale industrial plants

Definitions

• the invention relates to a device and a method for the production of anhydrous or largely anhydrous formic acid and the use of a water vapor stream in this method.
• a process described in EP-B-0 017 866 and comprising process steps a) to g) enables the production of anhydrous formic acid starting from methyl formate.
• Formic acid-containing overhead product is returned to the lower part of the distillation column of stage (b), f) the bottom product of the distillation stage (d), which predominantly contains extractant and formic acid, is distilled into anhydrous formic acid and the extractant and g) the extractant leaving stage (f) leads back into the process. It is particularly useful in this process
• k) use methyl formate and water in the hydrolysis (a) in a molar ratio of 1: 2 to 1:10 and / or 1) a carboxamide of the general formula I as extractant
• radicals R 1 and R 2 are alkyl, cycloalkyl, aryl or aralkyl groups or R 1 and R 2 together with the N atom form a heterocyclic 5- or 6-ring and that only one of the radicals is an aryl group and in which R 3 represents hydrogen or a Cj-C 4 alkyl group.
• the hydrolysis is usually carried out in a temperature range from 80 to 150 ° C.
• Process step (b) is usually carried out in a temperature range from 80 to 150 ° C.
• the distillation of the hydrolysis mixture can in principle be carried out at any pressure, preferably 0.5 to 2 bar. In general, working under normal pressure is recommended. In this case, the temperature in the column bottom is about 110 ° C and at the top of the column about 30 to 40 ° C.
• the hydrolysis mixture is expediently added in a temperature range from 80 to 150 ° C., and the methanol is preferably removed in liquid form at temperatures from 55 to 65 ° C.
• a satisfactory separation of the mixture into methyl formate and methanol on the one hand and the aqueous formic acid on the other hand is already possible with a distillation column which has 25 theoretical plates (a theoretical plate number from 35 to 45 is preferred).
• the design of the column provided for process step (b) can be of any type, but a sieve plate or packed column is particularly recommended.
• liquid-liquid extraction of formic acid from its aqueous solution by means of an extractant is preferably carried out in countercurrent at normal pressure and at temperatures from 60 to 120, in particular 70 to 90 ° C.
• extraction devices with 1 to 12 theoretical plates are generally required. Suitable extraction devices for this are in particular liquid-liquid extraction columns. In most cases, 4 to 6 theoretical plates give satisfactory results.
• extractant is not limited.
• Particularly suitable extractants are carboxamides of the general formula I mentioned above.
• Such extractants are primarily N, N-di-n-butylformamide and also N, N-di-n-butylacetamide, N-methyl-N-2-heptylformamide, Nn - Butyl-N-2-ethylhexylformamide, Nn-butyl-N-cyclohexylformamide and N- Ethyl formanilide and mixtures of these compounds.
• Other suitable extractants include diisopropyl ether, methyl isobutyl ketone, ethyl acetate, tributyl phosphate and butanediol formate.
• the extract phase is separated by distillation in a corresponding distillation device into a liquid phase, which as a rule has predominantly formic acid and extracting agent, and a vapor phase comprising predominantly water and small amounts of formic acid. It is an extractive distillation.
• the bottom temperature is preferably 140 to 180 ° C. A sufficient separation effect is usually achieved from 5 theoretical floors.
• the formic acid / water mixture is generally returned in vapor form.
• the distillation device (usually designed as a column) for carrying out stage (f) is advantageously operated under reduced pressure - about 50 to 300 mbar - and correspondingly low top temperatures - about 30 to 60 ° C.
• This variant of the method relates to steps (b) and (d).
• the distillation devices for carrying out stages b) and d) are arranged in an overall distillation device.
• the distillation devices are usually designed as columns.
• water required for the hydrolysis is provided in the form of water vapor.
• the aqueous phase running out of the extraction device for carrying out the liquid-liquid extraction still contains small amounts of valuable substances, in particular formic acid and extracting agent. These substances must not get into the wastewater, since the extractants used are generally difficult to biodegrade.
• a multi-column adsorber circuit is generally used to purify the wastewater and to recycle the valuable materials, the purchase and operation of which is very expensive. The regeneration of the adsorbent is usually particularly complex.
• Activated carbon is predominantly used as the adsorbent.
• the object of the present invention is to provide a method by which the "recovery of valuable materials is ensured from the Exfr relies adopted leaving waste water. In this case, the waste water will be so thoroughly cleaned of the useful materials and optionally of other impurities that further purification of the waste water The process should be practicable and economically attractive.
• the process according to the invention is characterized in that water vapor which is introduced into the destillation device provided for carrying out stage (ii) is used as stripping steam for stripping the waste water discharged from the process in stage (iii) before it is introduced into this distillation device ,
• anhydrous formic acid should be understood to mean formic acid which. contains a maximum of 30%, preferably a maximum of 15% water.
• Water vapor is to be understood as gaseous water, the latter also being able to contain liquid components and other components (apart from water).
• the process according to the invention is particularly economical since the water vapor which is anyway required for the process is also used for wastewater treatment.
• the process is energy-saving, requires little investment and is easy to carry out.
• the process enables the wastewater to be cleaned so effectively that the wastewater can then be fed directly into a sewage treatment plant. In addition, valuable materials from the process are recovered and recycled.
• radicals R 1 and R 2 are alkyl, cycloalkyl, aryl or aralkyl groups or R 1 and R 2 together with the N atom form a heterocyclic 5- or 6-ring and that only one of the radicals is an aryl group and in which R 3 represents hydrogen or a C 1 -C 4 -alkyl group.
• Particularly preferred extraction agents are N, N-di-n-butylformamide, NN-di-n-butylacetamide, N-methyl-N-2-heptylformamide, Nn-butyl-N-2-ethylhexylformamide, Nn-butyl-N-cyclohexylformamide and / or N-ethyl formanilide.
• a single extractant or an extractant mixture can be used as the extractant.
• steps (ii) and (iv) are carried out in a single distillation device.
• the steam used as stripping steam generally has a temperature of 110 to 200 ° C, preferably 140 ° to 180 ° C.
• the temperature at which the stripping steam is introduced into the distillation device is usually lower.
• the invention also relates to the use of a water vapor stream in the method described above.
• the water vapor stream is first used as a stripping steam stream for wastewater stripping and then as an educt stream for providing water for the hydrolysis of methyl formate.
• a device for carrying out the method described above is also provided. This contains
• a synthesis reactor ß) a hydrolysis reactor ⁇ ) a distillation device for performing step (ii), ⁇ ) a distillation device for performing step (iv), ⁇ ) an extraction device ⁇ ) a distillation device for performing step (vi) and ⁇ ) a wastewater stripping device.
• a synthesis reactor is to be understood as a device in which, on the one hand, the methyl formate is synthesized (usually in a corresponding reactor) and in which, on the other hand, the hydrolysis mixture obtained is also separated (usually in a distillation device downstream of the reactor).
• the hydrolysis reactor in which the hydrolysis of methyl formate takes place, can be of any design. Distillation columns are preferably used as distillation devices.
• the extraction device is generally designed as a liquid-liquid extraction column.
• a stripping column is generally used as the wastewater stripping device. This stripping column usually has 3 to 20, preferably 5 to 10, thermodynamic separation stages.
• the distillation device for carrying out step (ii) and the distillation device for carrying out step (iv) is arranged in a single distillation device.
• the latter is usually designed as a distillation column.
• FIGS. 1 and 2 for carrying out a method according to the prior art and the systems shown in FIGS. 3 and 4 for carrying out the method according to the invention have in common that they have a synthesis reactor 6, a hydrolysis reactor 1, a distillation device 2 for carrying out step (ii), a distillation device 4 for carrying out step (iv), an extraction device 3 and a distillation device 5 for carrying out step (vi).
• the distillation devices 2, 4 can be arranged in a common distillation device 7.
• the systems for carrying out the process according to the invention (FIGS. 3 and 4) contain a waste water stripping device 10.
• the cleaned waste water is fed from this into the sewage treatment plant 9.
• the systems shown in FIG. 1 or FIG. 2 for carrying out the method according to the prior art contain an adsorber device 8 instead of the waste water stripping device 10.
• the example test is carried out in a system which is shown schematically in FIG. 4.
• N, N-di-n-butylformamide is used as the extractant.
• 5.3 kg of aqueous formic acid are continuously produced. Here fall approx. 400 g / h waste water.
• the wastewater is stripped in a stripping column with about 1 kg / h steam.
• the extractant is completely removed from the waste water.
• the pilot plant column used for stripping has a diameter of 30 mm and is equipped with 30 bubble-cap trays. The results of the experiment are shown in Table 1 below.
• Table 1 shows that the inventive extractant N, N-di-n-butylformamide can be removed completely and formic acid can largely be removed from the waste water.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Crystallography & Structural Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Heat Treatment Of Water, Waste Water Or Sewage (AREA)
• Treatment Of Water By Oxidation Or Reduction (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (2)

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• 2000
  • 2000-01-24 DE DE10002794A patent/DE10002794A1/de not_active Withdrawn
• 2001
  • 2001-01-12 KR KR1020027009417A patent/KR100772760B1/ko not_active Expired - Fee Related
  • 2001-01-12 US US10/181,455 patent/US6867329B2/en not_active Expired - Lifetime
  • 2001-01-12 BR BRPI0107825-9A patent/BR0107825B1/pt not_active IP Right Cessation
  • 2001-01-12 JP JP2001555013A patent/JP4681192B2/ja not_active Expired - Fee Related
  • 2001-01-12 CN CNB018040659A patent/CN1271034C/zh not_active Expired - Fee Related
  • 2001-01-12 DE DE50115031T patent/DE50115031D1/de not_active Expired - Lifetime
  • 2001-01-12 EP EP01907445A patent/EP1250305B1/de not_active Expired - Lifetime
  • 2001-01-12 AU AU2001235416A patent/AU2001235416A1/en not_active Abandoned
  • 2001-01-12 AT AT01907445T patent/ATE439339T1/de not_active IP Right Cessation
  • 2001-01-12 WO PCT/EP2001/000346 patent/WO2001055069A2/de not_active Ceased
  • 2001-01-16 MY MYPI20010183A patent/MY131970A/en unknown
• 2002
  • 2002-07-22 NO NO20023481A patent/NO327831B1/no not_active IP Right Cessation

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