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
• • 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
• • 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
  • C07C51/42—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 the extracting agent used in the method.
• Methyl formate which is synthesized from methanol and carbon monoxide. The following equations are used:
• Extractant extracted d) subjecting the formic acid, extractant and an extract phase containing a portion of the water to a distillation, e) returning the water obtained in this distillation and a portion of the top product containing formic acid to the lower part of the distillation column of stage (b), f) separating the bottom product of the distillation stage (d), which contains predominantly extracting agent and formic acid, into anhydrous formic acid and the extracting agent by distillation and g) returning the extracting agent leaving stage (f) to the recycling process.
• 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 -CC 4 alkyl group.
• the hydrolysis 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 number of plates 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, above all, N-di-n-butylformamide and also N-di-n-butylacetamide, N-methyl-N-2-heptylformamide and Nn-butyl-N -2-ethylhexylformamide, N-n-butyl-N-cyclohexylformamide and N-ethylformanilide and mixtures of these compounds.
• Other suitable extraction agents 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, as well as a phase containing 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 vaporized.
• 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.
• exhaust gas streams are released in particular at the tops of the existing distillation columns. These are usually passed through capacitors, condensable components being condensed out and then returned to the process. The components that have not condensed out on the condensers and remain in the gas phase are discarded as exhaust gas or are fed to exhaust gas combustion. Exhaust gas combustion is expensive. In addition, valuable substances, in particular methyl formate, methanol and / or formic acid, are generally also contained in the exhaust gas stream. The combustion of these valuable materials reduces the economics of the process.
• the discharge of exhaust gas streams which are usually in addition to those mentioned above Recyclable materials still contain inert gases, for example carbon monoxide, but is necessary since otherwise inert gases would accumulate in the process and the function of the capacitors would be impossible.
• the object of the present invention is to produce a method in which exhaust gas flows are discharged from the method, but the losses of valuable materials and disposal costs are minimized. It is essential that the process can be carried out economically.
• radicals R 1 and R 2 are alkyl, cycloalkyl, aryl or aralkyl groups or form Ri and R 2 together with the N atom a heterocyclic 5- or 6-membered ring and in which only one of the radicals is an aryl group and in which R 3 represents hydrogen or a Cr alkyl group.
• the process according to the invention is then characterized in that gaseous exhaust gas streams obtained in the process and containing methyl formate and / or methanol and or formic acid are washed with the extractant used before being discharged from the process, methyl formate and / or methanol and / or formic acid being washed in dissolve the extractant and the extractant loaded with methyl formate and / or methanol and / or formic acid is returned to the process.
• one or more exhaust gas streams can be washed with the extractant. It is advantageous to combine exhaust gas flows and then to subject them to washing. However, several exhaust gas streams can also be introduced into the exhaust gas scrubbing device provided for the exhaust gas scrubbing.
• the waste gas streams washed out with extractant can advantageously be disposed of without subsequent waste gas combustion. This saves considerable costs.
• the recycling of the valuable substances, in particular methyl formate and / or methanol and / or formic acid, can also save considerable costs. It is essential that the solvent used for washing is used at the same time as an extracting agent for formic acid and as a washing liquid for the exhaust gas - no additional auxiliary substance therefore has to be introduced into the process for carrying out the exhaust gas scrubbing. This is of considerable economic importance.
• the extracting agents used for the process are relatively low volatility and can therefore not be stripped from the exhaust gas stream to be cleaned.
• the extractant used for washing can also contain other components, in particular formic acid, in addition to the “actual extractant”.
• the extractant is usually fed to the exhaust gas scrubbing device at a temperature between 10 and 60 ° C., in particular between 20 and 50 ° C.
• the waste gas streams washed with the extractant used are obtained in step ii) and / or step vi) of the method according to the invention.
• the exhaust gas streams are usually taken from the top of the corresponding distillation columns and fed to condensers.
• the condensable components contained in the exhaust gas stream are then partially removed from the exhaust gas streams by condensation.
• the condensed components are then generally fed into the process, while the exhaust gas freed from the condensed components is fed to the laundry.
• condensable components are to be understood as meaning components such as methanol, formic acid or methyl formate which can be condensed out at 0 ° C.
• non-condensable components since these remain completely in the exhaust gas stream.
• condensable components are generally only partially condensed. The non-condensed parts enter the exhaust gas stream, which is washed with the extractant.
• the extractant loaded with methyl formate and / or methanol and / or formic acid after washing is usually returned to the process in step iii) and / or step iv) - this generally corresponds to the return to the extraction device and / or the distillation device to carry out stage vi).
• the extracting agent used for washing is taken as a partial stream from the extracting agent leaving stage vi) and / or the extract phase essentially containing formic acid and extracting agent.
• the exhaust gas is usually washed with the extractant in an exhaust gas washing device.
• the invention also relates to the use of a carboxamide of the general formula I.
• radicals R 1 and R 2 are alkyl, cycloalkyl, aryl or aralkyl groups or R and R together with the N atom form a heterocyclic 5- or 6-ring and in which only one of the radicals is an aryl group and in which R 3 represents hydrogen or a C 1 -C alkyl group, in the process described above as an extractant for the liquid-liquid extraction of formic acid and as a washing liquid for gaseous exhaust gas streams containing methyl formate and / or methanol and / or formic acid.
• a synthesis reactor is to be understood as a device in which, on the one hand, methyl formate is synthesized (usually in a corresponding reactor) and in which, on the other hand, a separation of the synthesis mixture obtained is usually carried out (usually in a distillation device downstream of the reactor). Any reactor with which the hydrolysis of methyl formate can be carried out can be used as the hydrolysis reactor. Distillation columns are particularly suitable as distillation devices. For the extraction of formic acid, an extraction device is used in particular, which is designed as a liquid-liquid extraction column. An exhaust gas scrubbing device, which is preferably designed as a scrubbing column, is generally used to carry out the exhaust gas scrubbing. This usually contains 3 to 20, especially 4 to 10, theoretical plates.
• the distillation device for carrying out step ii) and the distillation device for carrying out step iv) are arranged in a single distillation device.
• the latter is usually designed as a distillation column.
• the currents marked with arrows are partially provided with reference symbols. These indicate the components contained in these streams, which usually have the largest share in them. Since the proportions of the components in the currents can vary, these reference symbols serve only as a guide. 21 mean methyl formate, 22 water, 23 formic acid, 24 methanol, 25 extractant and 27 carbon monoxide.
• the systems for carrying out the method according to the prior art (FIG. 1, FIG. 2) and the systems for carrying out the method according to the invention (FIGS.
• distillation devices 2; 4 have in common that they have a synthesis reactor 6, a hydrolysis reactor 1, have a distillation device 2 for carrying out step ii), a distillation device 4 for carrying out step iv), an extraction device 3 for carrying out step iii) and a distillation device 5 for carrying out step vi).
• the distillation devices 2; 4 can be arranged in a single distillation device 7.
• the systems shown in FIGS. 3 and 4 for carrying out the method according to the invention have a vacuum pump 8, a gas washing device 9 and a line 13 for supplying the extracting agent into the gas washing device 9 on.
• the exhaust gas leaves the process via a line 12, which is arranged behind capacitors.
• the line 12, through which exhaust gas is discharged from the process is connected downstream of the exhaust gas washing device 9.
• the example is based on a method according to the invention, which is carried out in a system which is shown schematically in FIG. 4.
• 5.3 kg / h of aqueous formic acid are continuously produced in the plant.
• the laboratory column used as an exhaust gas washing device has a diameter of 30 mm and is equipped with 30 bubble-cap trays.
• the test results show that the exhaust gas after washing is largely freed from the valuable substances formic acid, methyl formate and methanol.
• the cleaned exhaust gas only contains 1.8% by weight of valuable substances, while the unpurified exhaust gas contains a total of 54.4% by weight of valuable substances.
• the extractant N, N-di-n-butylformamide used is suitable as a scrubbing liquid for the waste gases released in the process.

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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)
• Treating Waste Gases (AREA)
• Gas Separation By Absorption (AREA)
• Lasers (AREA)
• Glass Compositions (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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• 2000
  • 2000-01-24 DE DE10002790A patent/DE10002790A1/de not_active Withdrawn
• 2001
  • 2001-01-16 MY MYPI20010185A patent/MY128445A/en unknown
  • 2001-01-24 EP EP01946839A patent/EP1250306B1/de not_active Expired - Lifetime
  • 2001-01-24 BR BRPI0107823-2A patent/BR0107823B1/pt not_active IP Right Cessation
  • 2001-01-24 WO PCT/EP2001/000747 patent/WO2001055070A2/de not_active Ceased
  • 2001-01-24 AT AT01946839T patent/ATE309187T1/de not_active IP Right Cessation
  • 2001-01-24 JP JP2001555014A patent/JP4908713B2/ja not_active Expired - Fee Related
  • 2001-01-24 KR KR1020027009416A patent/KR100830758B1/ko not_active Expired - Fee Related
  • 2001-01-24 DE DE50107981T patent/DE50107981D1/de not_active Expired - Lifetime
  • 2001-01-24 CN CNB018040624A patent/CN1304350C/zh not_active Expired - Fee Related
  • 2001-01-24 AU AU2001228486A patent/AU2001228486A1/en not_active Abandoned
  • 2001-01-24 US US10/181,458 patent/US6696603B2/en not_active Expired - Lifetime
• 2002
  • 2002-07-22 NO NO20023480A patent/NO327886B1/no not_active IP Right Cessation

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