Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D295/00—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms
  • C07D295/02—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms containing only hydrogen and carbon atoms in addition to the ring hetero elements
  • C07D295/023—Preparation; Separation; Stabilisation; Use of additives
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D295/00—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms
  • C07D295/22—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with hetero atoms directly attached to ring nitrogen atoms
  • C07D295/28—Nitrogen atoms

Definitions

• the present invention relates to a process for the selective separation of morpholine from an aqueous solution which contains morpholine, N-methylmorpholine and N-methylmorpholine-N-oxide.
• the present invention relates in particular to a process for working up an aqueous process liquid of the amine oxide process which contains morpholine, N-methylmorpholine and N-methylmorpholine-N-oxide.
• NMMO N-Methylmorpholine-N-oxide
• Other amine oxides are described, for example, in EP-A-0 553 070.
• a method for producing moldable cellulose solutions is known, for example, from EP-A-0 356 419.
• the production of cellulosic molded articles using tertiary amine oxides is generally referred to as amine oxide process for the purposes of the present description and the present patent claims.
• EP-A-0 356 419 describes an amine oxide process for the preparation of spinnable cellulose solutions which uses, among other things, a suspension of cellulose in liquid, aqueous N-methylmorpholine-N-oxide (NMMO) as the starting material.
• NMMO N-methylmorpholine-N-oxide
• This process consists in the suspension being continuously and continuously converted into a moldable solution in a thin-film treatment apparatus.
• the moldable solution is finally spun in a molding tool, for example a spinneret, into filaments which are passed through a precipitation bath.
• the cellulose is precipitated in the precipitation bath.
• the tertiary amine oxide accumulates in the precipitation bath.
• the amine oxide content in the precipitation bath can be up to 30% by weight.
• a process for the recovery of NMMO from dilute aqueous solutions is known from DD-A-274 435. According to this method, the aqueous solution is passed through exchange columns filled with styrene / divinylbenzene copolymer containing SO 3 H groups to the maximum equimolar loading, then the NMMO is displaced by equimolar amounts of sodium hydroxide solution and the exchange columns are regenerated with acid.
• degradation products of the amine oxide process also accumulate in the precipitation bath with the amine oxide. These degradation products can be strongly colored and thus impair the quality of the cellulosic molded articles produced. Other substances, in turn, can additionally pose a safety risk, since under certain conditions the amine oxide tends to undergo strongly exothermic decomposition reactions and induce these decomposition reactions from certain substances or can be accelerated. These substances must be removed from the precipitation bath to be processed before the concentration and separation of NMMO.
• the cleaned precipitation bath which may be mixed with other process waters of the amine oxide process, e.g. Vapor condensates, which are obtained in the production of the cellulose solution, are combined, water is removed. This can be done, for example, by evaporation. In the bottom of this evaporation, highly concentrated, aqueous amine oxide is obtained, which is recycled back into the amine oxide process.
• the vapors of the evaporation mainly consist of water, in which considerable amounts of N-methylmorpholine, the main degradation product of the NMMO, are also dissolved. NMMO and morpholine can also be found in the brothers.
• the vapors typically contain up to 100 mg NMMO, up to 240 mg N-methylmorpholine and up to 30 mg morpholine per liter. They are expediently concentrated, for example by reverse osmosis.
• the aqueous solution obtained typically contains up to 4 g of NMMO, up to 10 g of N-methylmorpholine and up to about 1 g of morpholine.
• amines can be removed from waste water from cellulose processing by means of a cation exchanger.
• the cation exchanger carries carboxyl groups as functional groups.
• the cation exchanger loaded with the amines is then treated with an aqueous solution of a weak acid which has a pKa greater than 3.0 in order to elute the amines.
• the eluate is worked up by distillation, part of the weak acid being separated from the amines and optionally being recovered. This process removes up to 94% of the wastewater from aqueous solutions containing N-methylmorpholine and morpholine.
• the separated amines are disposed of by incineration.
• EP-A-0 468 951 describes a process for the separation of amine oxides from aqueous solutions, in particular waste water which is obtained in the processing of cellulose.
• the waste water is brought into contact with a cation exchanger which has carboxyl groups as functional groups in order to load the cation exchanger with the amine oxides, whereupon the loaded cation exchanger is washed and the amine oxides are washed with an aqueous solution of a weak acid with a pKa value of greater than 3.0 is treated to elute the amine oxides.
• This process also aims to completely remove the amine oxides from the waste water in order to be able to dispose of them in an environmentally friendly manner.
• N-methylmorpholine should also be oxidized again to NMMO and recycled.
• the oxidation is accomplished, for example, with a peroxidic oxidizing agent.
• a process for the preparative preparation of tertiary amine oxides by oxidation of tertiary amines is known for example from EP-A - 0 092 862.
• the amine oxide is oxidized in an aqueous solvent with molecular oxygen under pressure, which solvent has a pH value which is approximately equal to or higher than the pKa value of the tertiary amine.
• DD-A - 259 863 relates to the preparation of aqueous NMMO solutions by oxidation of N-methylmorpholine with H_0 2 and passing the reaction solution over one or more exchange columns containing sulfonate groups Styrene / divinylbenzene copolymer are filled, and by adjusting the pH of the solution to values between 8 and 5 by adding phosphoric acid.
• DE-A -4 140 259 the production of NMMO is known, in which process the formation of nitrosamines is prevented by trapping primary and secondary amines, for example with acid halides.
• EP-A-0 320 690 describes the production of essentially nitrosamine-free amine oxides by oxidation using peroxides in the presence of a combination of CO 2 / ascorbic acid, which acts as a nitrosamine inhibitor.
• the oxidation with H 2 0 2 in water and a cosolvent, preferably a carboxylic acid ester is known.
• FR-A-8 808 039 the oxidation is carried out with the addition of C0 2 , and according to US-A-5,216,154, the oxidation to NMMO is carried out in a pure C0 2 atmosphere.
• the present invention therefore aims to provide a process for the selective separation of morpholine from various process waters of the amine oxide process, in which essentially only morpholine is separated and NMMO and N-methylmorpholine remain in the process water.
• the process according to the invention for the selective separation of morpholine from an aqueous solution which contains morpholine, N-methylmorpholine and NMMO is characterized by the following steps:
• step (B) the cation exchanger loaded with morpholine is regenerated and used again in step (A).
• the present invention is based on the knowledge that a cation exchanger apparently has a higher activity for morpholine than N-methylmorpholine and NMMO and that this higher activity is sufficient that at the time when morpholine begins to break through, N- Methylmorpholine and NMMO are already eluted in high yield, which enables a sharp separation of the morpholine.
• the separation takes place in such a way that all three components, ie morpholine, N-methylmorpholine and NMMO, are initially adsorbed on the fresh cation exchanger.
• NMMO begins to break through, since both upcoming NMMO can no longer be adsorbed, and subsequent morpholine and N-methylmorpholine displace already adsorbed NMMO. This means that the eluate contains practically only NMMO at this time.
• N-methylmorpholine also appears in the eluate, which is displaced by the morpholine that follows. At this point the eluate contains NMMO and N-methylmorpholine. Only when essentially no more N-methylmorpholine is adsorbed on the cation exchanger and the capacity of the cation exchanger is exhausted does morpholine begin to break through and the elution must be stopped and the cation exchanger regenerated. This can be done, for example, with dilute mineral acids.
• the cation exchanger used in the process according to the invention preferably has carboxyl groups and / or sulfonic acid groups.
• step (C) the eluate obtained in step (A) is optionally subjected to an oxidation treatment after removal of water in order to oxidize N-methylmorpholine to N-methylmorpholine-N-oxide.
• This variant of the method according to the invention ensures that a new formation of the toxic N-nitrosomorpholine is practically completely suppressed, since the eluate contains practically no morpholine.
• the oxidized eluate thus only contains the usual low basic level of N-nitrosomorpholine, which is established in the amine oxide process.
• the oxidation is expediently carried out using a peroxidic oxidizing agent.
• H 2 0 2 is preferably used as the peroxidic oxidizing agent in the process according to the invention.
• the H 2 0 2 is preferably used in the form of an aqueous solution with 30-50% by weight H 2 0_.
• the H 2 0_ is best used in an amount of 0.8 to 2 moles per mole of N-methylmorpholine.
• a further preferred embodiment of the method according to the invention is characterized in that the aqueous solution is irradiated with or after the oxidation treatment with ultraviolet light, which essentially has a wavelength of 254 nm, the ultraviolet light preferably originating from a low-pressure mercury lamp.
• This variant of the method according to the invention is based on the discovery that N-nitrosomorpholine can be destroyed by irradiation with ultraviolet light with an intensity maximum of 254 nm. Therefore, when the ultraviolet light is irradiated during or after the oxidation treatment, the basic N-nitrosomorpholine is destroyed, thereby making it possible to significantly lower the basic level of this toxic substance.
• the lamp can be suspended in the container which contains the process water to be treated.
• the lamp can also be arranged in a different way.
• the irradiation can also be carried out, for example, while the solution to be irradiated is continuously pumped around in a thin-film UV reactor.
• the process according to the invention is particularly suitable for working up a process water from the amine oxide process.
• the eluate obtained from the cation exchanger is combined with purified precipitation bath of the amine oxide process which contains 10-30% by weight NMMO, and (3) the eluate combined with the coagulation bath is treated in an evaporation reactor with the peroxidic oxidizing agent in order to oxidize and to concentrate N-methylmorpholine, whereby concentrated, aqueous NMMO, which is again recycled into the amine oxide process, and vapors are obtained, which condenses and used in step (1).
• NMOR N-nitrosomorpholine
• N-methylmorpholine-N-oxide N-methylmorpholine
• morpholine morpholine
• a process water from the amine oxide process namely a retentate from a reverse osmosis, was passed through a weakly acidic cation exchanger (polyacrylic structure with carboxyl groups as functional groups; Dowex CC-2; manufacturer: The Dow Chemical Company).
• the retentate had a pH of 9.9 and the following composition:
• cation exchanger 30 ml of cation exchanger were used in a column with a diameter of 2.5 cm and a height of about 5.5 cm.
• the retentate was passed through the cation exchanger at a flow rate of 4 bed volumes per hour.
• the eluates were collected at intervals of 5 bed volumes each, and then the pH and the concentrations of NMMO, NMM and M were determined.
• the cation exchanger started to swell after 10 bed volumes and the swelling continued until the end of loading and was 150% after 200 bed volumes.
• the concentrations (ppm) of NMMO, NMM and M were determined by HPLC (column: Hypersil Si 150 x 4 mm; 50 "C; eluent: 52% Acetonitrii for UV, Fisions Scientific Equipment, No. A / 0627/17; 48 % 10 mmol KH 2 P0 4 (Merck No. 4873), adjusted to pH 6.7 with NaOH; isocratic 1 ml / min; detector: UV 192 nm.
• the individual components were quantified by calibrating an external 3-point calibration. The results are shown in the table below.
• NMMO begins to elute, while NMM and M are retained, so that the eluate contains practically only NMMO up to the 40th bed volume.
• the elution of NMMO is probably due to a displacement of the already adsorbed NMMO from the cation exchanger by subsequent NMM and M.
• NMM From the 40th bed volume, NMM also begins to elute while M is held back. The pH continues to rise to around 8-9. Apparently adsorbed NMM is displaced by the M supplied at the ion exchanger.
• the temperature of the process water was 50 ° C.
• the NMOR concentration rose to 45 ⁇ g / l, which is due to a quick reaction of the M in the solution. Afterwards, however, the concentration of NMOR decreased sharply. No NMOR was detectable after 6 hours.
• the solution contained 5386 mg NMMO / liter. This corresponds to a yield of 62% of theory.

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• 1995
  • 1995-08-18 AT AT140395A patent/AT403297B/de not_active IP Right Cessation
• 1996
  • 1996-08-16 WO PCT/AT1996/000146 patent/WO1997007108A1/de not_active Application Discontinuation
  • 1996-08-16 CA CA 2202153 patent/CA2202153A1/en not_active Abandoned
  • 1996-08-16 AU AU66954/96A patent/AU700207B2/en not_active Ceased
  • 1996-08-16 EP EP96926960A patent/EP0783497A1/de not_active Ceased
  • 1996-08-16 BR BR9606585A patent/BR9606585A/pt not_active Application Discontinuation
  • 1996-08-16 CN CN96191128A patent/CN1071750C/zh not_active Expired - Fee Related
  • 1996-08-16 JP JP9508733A patent/JPH10508318A/ja not_active Ceased
• 1997
  • 1997-04-17 NO NO19971753A patent/NO310572B1/no not_active IP Right Cessation

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