WO2013020798A1 - Procédé d'épuration des eaux usées provenant du traitement de composés nitroaromatiques bruts - Google Patents

Procédé d'épuration des eaux usées provenant du traitement de composés nitroaromatiques bruts Download PDF

Info

Publication number
WO2013020798A1
WO2013020798A1 PCT/EP2012/064368 EP2012064368W WO2013020798A1 WO 2013020798 A1 WO2013020798 A1 WO 2013020798A1 EP 2012064368 W EP2012064368 W EP 2012064368W WO 2013020798 A1 WO2013020798 A1 WO 2013020798A1
Authority
WO
WIPO (PCT)
Prior art keywords
aqueous phase
res
phase
stage
organic
Prior art date
Application number
PCT/EP2012/064368
Other languages
German (de)
English (en)
Inventor
Julia Leschinski
Petra Deckert
Leo Denissen
Bart Van De Voorde
Stefan Robert DEIBEL
Matthias FANKHÄNEL
Samuel Neto
Original Assignee
Basf Se
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Basf Se filed Critical Basf Se
Publication of WO2013020798A1 publication Critical patent/WO2013020798A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
    • C07C201/06—Preparation of nitro compounds
    • C07C201/16—Separation; Purification; Stabilisation; Use of additives
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/26—Treatment of water, waste water, or sewage by extraction
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/32—Hydrocarbons, e.g. oil
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/38—Organic compounds containing nitrogen
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C02F2103/36—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the manufacture of organic compounds

Definitions

  • the invention relates to a process for the purification of crude aromatic nitro compounds derived from the nitration of aromatic compounds, comprising the following washing steps (a1) and (a2), wherein each of the steps (a1) and (a2) is carried out one or more times in succession can be:
  • step (a2) contacting the organic phase (N1 -res) obtained in step (a1) with a second aqueous phase (W2-ein) and subsequent phase separation to obtain a purified organic phase (N2-res) and at least one aqueous phase (W2-res) Res), wherein the aqueous phase used (W2-one) has a pH of 6 to 9.
  • Aromatic nitro compounds in particular mononitrobenzene, are usually prepared in commercial processes by direct nitration of benzene with a mixture of nitric acid and sulfuric acid, the so-called nitrating acid.
  • This reaction is a two-phase reaction whose rate of reaction is determined by mass transfer between phases and by chemical kinetics.
  • adiabatic reaction has recently acquired particular importance.
  • the reaction product obtained from the nitration of the aromatic starting compound (crude product), in particular mononitrobenzene, is initially obtained as a two-phase mixture, the organic phase containing, in addition to the organic nitro compound, further organic by-products and unconverted organic starting materials.
  • the aqueous phase comprises, in addition to organic constituents such as, for example, mononitrobenzene and benzene, naturally unused nitrating acid.
  • the acidic aqueous phase is usually concentrated in the prior art in a sulfuric acid concentration (SAC) and recycled back into the nitration reaction.
  • SAC sulfuric acid concentration
  • crude aromatic nitro compound (N1 -ein) This obtained by phase separation, derived directly from said nitration organic phase, hereinafter referred to as crude aromatic nitro compound (N1 -ein), with both organic minor components such.
  • crude aromatic nitro compound (N1 -ein) As dinitrobenzene, benzene, nitro phenols and contaminated with nitrating acid and requires a multi-stage workup, the high demands in terms of energy and process costs, yield and purification of waste streams must comply with environmental aspects. Processes for working up crude aromatic nitro compounds are known in the art.
  • the separation of the crude aromatic nitro compound (N1 -ein), especially crude mononitrobenzene from the acidic aqueous phase is followed by at least one washing of the crude aromatic nitro compound (N1-a) with water or an aqueous solution.
  • the aqueous phase which results from the abovementioned washing process (hereinafter referred to as wastewater) comprises, in addition to water and salts, organic compounds such as mononitrobenzene, dinitrobenzene, nitrophenols (mono- and polynitrated phenols) and benzene.
  • organic compounds such as mononitrobenzene, dinitrobenzene, nitrophenols (mono- and polynitrated phenols) and benzene.
  • WWTP biological wastewater treatment plant
  • EP 1 593 654 A1 describes a process for working up alkaline wastewaters, which are produced during the scrubbing of crude nitrobenzene, wherein the crude nitrobenzene is prepared by adiabatic nitration of benzene with nitrating acid and then washed in an acidic scrub and then in an alkaline scrubber in which an alkaline waste water containing benzene in concentrations of 100 to 3000 ppm and nitrobenzene in concentrations of 1000 to 10000 ppm is obtained. The benzene and / or nitrobenzene present in solution is then dissolved out of the alkaline wastewater, and optionally residual benzene and / or nitrobenzene are removed by stripping from the alkaline wastewater.
  • Acid waste water according to the prior art, however, are disadvantageous in terms of further processing. As a rule, they contain ingredients that have to be removed before being fed into a biological wastewater treatment with additional effort. Acid wastewater often also lead to corrosion problems at subsequent purification stages, which can only be remedied by additional technical effort.
  • state-of-the-art wastewater contains nitrophenolate or nitrophenols in all stages, so that all effluents have to be fed to a complex and expensive thermolytic decomposition. It is thus desirable to provide a process for the purification of crude aromatic nitro compounds which supplies at most a portion of the effluents to a thermolytic water treatment.
  • the separation of the organic constituents from the wastewater can be carried out for example by a possibly multi-stage extraction with benzene.
  • a known process is the optionally multi-stage stripping of the organic constituents with water vapor, in which, in particular, low-boiling organic impurities are removed, and subsequent thermolytic or oxidative decomposition of organic constituents still present in the resulting wastewater.
  • EP 0 953 546 A2 describes a process for the degradation of aromatic nitro compounds in wastewaters by heating the wastewater to temperatures of 150 to 350 ° C under a pressure of 10 to 300 bar.
  • EP 0 953 546 A2 states that the wastewaters treated in this way can be biologically purified.
  • Nitrification is the bacterial oxidation of ammonia (NH 3 ) to nitrate (N0 3 ⁇ ). It consists of two coupled subprocesses: In the first part, ammonia is oxidized to nitrite, which is oxidized to nitrate in the second subprocess.
  • the nitrification is associated with a production of acid (H + formation), the pH is lowered when the acid formed is not neutralized, such as by reaction with calcium carbonate (CaC0 3 ).
  • the acid formed pollutes the buffering capacity of the water and can acidify the water or the soil. Since nitrifying microorganisms change metabolites only in the neutral to slightly alkaline range, acidification can prevent the complete conversion of fish toxic ammonia / ammonia into sewage treatment plants (autoinhibition).
  • Denitrification is understood to mean the conversion of nitrogen bound in the nitrate (N0 3 ⁇ ) to molecular nitrogen (N 2 ) by certain heterotrophic and some autotrophic bacteria, which are subsequently referred to as denitrifiers.
  • the waste water produced according to the prior art can be supplied to the biological wastewater treatment only after a complex workup with removal of all nitrophenols.
  • the object of the present invention to provide a process for the purification of crude products from the nitration of aromatic compounds, which does not have the aforementioned disadvantages or to a lesser extent.
  • the process should at least partially generate effluents, which may optionally be fed, after stripping and optionally removal of ammonia, directly to biological wastewater treatment, with the omission of thermal and / or oxidative work-up.
  • the total amount of wastewater produced should be as low as possible.
  • the process comprises the following washing stages (a1) and (a2), wherein each of the
  • Steps (a1) and (a2) can be carried out one or more times in succession:
  • step (a2) contacting the organic phase (N1 -res) obtained in step (a1) with a second aqueous phase (W2-ein) and subsequent phase separation to obtain a purified organic phase (N2-res) and at least one aqueous phase (W2-res) Res), wherein the aqueous phase used (W2-one) has a pH of 6 to 10.
  • the crude aromatic nitro compound (N1 -a) used in step (a1) is obtained in particular as the organic phase in the nitration of the aromatic starting compound after separation from the aqueous phase formed during the nitration and in particular used directly in step (a1). Thus, in particular the stage (a1) upstream washing stages are excluded.
  • washing or “washing stage” characterizes the contacting of an organic phase with an aqueous phase, wherein at least one constituent of the organic phase at least partially changes into the aqueous phase, including the subsequent phase separation.
  • the washing of organic phases and the subsequent separation of the phases is known per se to those skilled in the art and can be carried out in known apparatuses such as mixing separation units (mixing unit followed by separation unit) or extractors such as. B. extraction columns.
  • the present process is particularly suitable for the treatment of effluents resulting from the purification of crude mononitrobenzene obtained by nitration of benzene. For this reason, the method is explained by way of example with reference to this specific purification. However, the person skilled in the art can easily transfer the abovementioned embodiments to aromatic starting compounds other than benzene or to products other than mononitrobenzene.
  • the crude aromatic nitro compounds which can be purified by the process according to the invention are preferably derived from nitration plants for the nitration of aromatic compounds, such as e.g. Nitrobenzene plants, Dinitrotoluolanlagen and Nitrotoluol- and Nitroxylolanlagen.
  • the crude aromatic nitro compound is crude mononitrobenzene obtained by nitration of benzene.
  • aromatic starting compounds in particular benzene
  • aromatic nitro compounds in particular mononitrobenzene
  • Suitable methods are described for example in EP 043 6 443 A2 and in Kirk-Othmer, Encyclopedia of Chemical Technology, "Nitrobenzene and Nitrotoluenes", published online on 14.10.2005.
  • a phase separation is first carried out, resulting in an organic phase containing mainly mononitrobenzene and unreacted benzene and traces of organic secondary components, in particular nitrophenols.
  • the aqueous phase contains essentially water and sulfuric acid. After separation of the water of reaction, the aqueous phase is usually fed again to the process, while the organic product phase (the crude aromatic nitro compound) is treated according to the invention. As a result, in particular nitrophenols are removed
  • Washing step (a1) The washing step (a1) explained below is also referred to as alkaline washing.
  • the crude aromatic nitro compound N1 -ein used in step (a1) is also referred to as organic phase N1-a and is obtained in particular as organic phase in the nitration of the aromatic starting compound and subsequent separation from the resulting aqueous phase and in particular directly in step (a1) used.
  • Washing stage (a1) according to the invention can be carried out several times in succession.
  • the crude aromatic nitro compound (N1-a) is contacted with a first aqueous phase (W1-a) comprising at least one base (B) and subsequent phase separation to give an organic phase (N1 -res) in the course of washing step (a1). and an aqueous phase (W1 -res).
  • a mixing device for carrying out step (a1) is known to the person skilled in the art.
  • intensive mixing of the two phases is first carried out in order to accelerate the formation of phenolates and the transition of phenolates from the organic phase (N1-one) to the aqueous phase (W1-one). It has proven to be advantageous to carry out the mixing with stirring.
  • the separation of the two phases preferably takes place in a second device, a phase separation apparatus.
  • Suitable phase separation apparatuses are in principle all apparatuses known to the person skilled in the art, in particular settlers and centrifuges.
  • the pH of the first aqueous phase (W1 ein) containing at least one base (B) in the form used is preferably from 9 to 14, particularly preferably from 9 to 12.5, in particular from 9.5 to 11.
  • Suitable bases (B) are, in particular, ammonia and alkali metal hydroxides.
  • Alkali metal hydroxides are preferred, in particular lithium hydroxide, sodium hydroxide, potassium hydroxide and / or rubidium hydroxide.
  • Sodium hydroxide is particularly preferred as the base.
  • the addition of the base (B) is preferably carried out in the form of aqueous solutions of the base, ie at least parts of the aqueous solution used in step (a) contain said base (B).
  • the preferably excessively added base (B) produces phenolates from the phenolic organic compounds and neutralizes the nitrating acid present in the organic phase to form soluble salts.
  • the resulting pH of the effluent (W1 res) is preferably from 8 to 14, particularly preferably 9 to 13, in particular 9 to 1 1
  • the washing step (a1) can be carried out several times in succession, preferably in two or three sub-steps (repetitions), preferably in a sequence of mixing and phase separation devices. It is advantageous to carry the aqueous phase (W1-ein) in the course of the washing stage (a1) in countercurrent to the organic phase (N1-in). As a result, prepurified organic phase comes into contact with the aqueous phase (W1-a), which has not yet undergone a sub-step. As a result, the phenolates can be completely extracted and transferred to the aqueous phase. In principle, numerous aqueous phases (W1-ein) come into consideration, as long as they meet the requirements with respect to base (B).
  • Nitrophenol-containing waste waters from the work-up of the nitrating acid are preferably used as the aqueous phase. This makes it possible to combine different nitrophenol-containing wastewater and thus to minimize the amount of wastewater from which nitrophenols have to be removed by thermolysis or ozonolysis.
  • the wastewater resulting from stage (a1) usually contains, in addition to water, residual amounts of benzene and nitrobenzene as well as nitrophenols.
  • the effluent resulting from step (a) typically contains benzene in concentrations of 10 to 3000 ppm, preferably 100 to 1000 ppm, and nitrobenzene in concentrations of 500 to 10,000 ppm, preferably 1200 to 8000 ppm.
  • the wastewater also usually contains nitrophenolates in a concentration of 1000 to 20,000 ppm, in particular 2,000 to 8,000 ppm.
  • the unit ppm in the context of the present invention basically refers to parts by weight.
  • nitrophenols which may also be present in the form of their water-soluble salts: mono-, di- and trinitrophenols, mono-, di- and trinitro-cresols, mono-, di- and trinitro-resorcinols, mono-, di- and trixylenols ,
  • washing Stage (a2) in the course of washing stage (a2), the organic phase (N1-res) obtained in stage (a1) is subsequently contacted with a second aqueous phase (W2-ein) and then phase-separated to obtain a purified organic Phase (N2-res) and at least one aqueous phase (W2-res), wherein the aqueous phase used (W2-one) has a pH of 6 to 9.
  • step (a2) is carried out in the absence of a base (B) in the aqueous phase (W2-in).
  • This single or multiple sequentially repeated washing step (a2) is also referred to as neutral washing.
  • step (a2) Devices for carrying out step (a2) are known to the person skilled in the art.
  • the same devices as in step (a1) can be used.
  • a mixing device intensive mixing of the two phases is first carried out in order to accelerate the transfer of salts from the organic phase (N2-one) to the aqueous phase (W2-one). It has proven to be advantageous to produce the mixing by stirring.
  • the separation of the two phases preferably takes place in a second device, a phase separation apparatus.
  • the washing step (a2) can be carried out several times in succession, preferably in one or two sub-steps (repetitions), preferably in a sequence of mixing and phase separation devices. It is advantageous, the aqueous phase (W2-a) in the context of the washing step (a2) in countercurrent to the organic phase (N2-one) to lead. As a result, the purified organic phase (N2-res) comes into contact with the aqueous phase, which has not yet undergone a sub-step. As a result, inorganic salts can be completely extracted and transferred to the aqueous phase.
  • the step (a2) is carried out in two sub-steps (repetitions) and the aqueous phase (W2-in) used during the washing step (a2) is passed countercurrently to the organic phase (N2-in) ,
  • aqueous phases W2-one
  • effluents are used which are substantially free of nitrophenols.
  • Essentially free of nitrophenols we refer to an aqueous phase when it contains not more than 30 ppm, in particular not more than 20 ppm of nitrophenols.
  • the aqueous phase W2-ein particularly preferably has a content of nitrophenols of not more than 5 ppm, in particular not more than 3 ppm. Accordingly, effluents from another manufacturing process are preferably used, which are substantially free of nitrophenols.
  • the aqueous phase (W2-in) used is a wastewater which results from the hydrogenation of mononitrobenzene to produce aniline.
  • the washing steps (a1) and (a2) are hereinafter referred to collectively as step (a).
  • the separation of the nitrobenzene which is not dissolved can take place by means of separators, settling tanks or other phase separation equipment. Preferably, a settling tank is used.
  • the said separation can alternatively be carried out in the form of an extraction, as described in WO 2009/027416.
  • the benzene and / or nitrobenzene thus separated is then preferably returned to the nitration process or to the crude nitrobenzene.
  • the aqueous phase W2-res resulting from washing stage (a2) preferably has a content of nitrophenols of not more than 20 ppm, in particular from 0.001 to 20 ppm.
  • the content of nitrophenols in W2-res is particularly preferably at most 10 ppm, in particular from 0.001 to 10 ppm, very particularly preferably at most 5 ppm, in particular from 0.001 to 5 ppm.
  • step (a1) is carried out in the presence of at least one demulsifier.
  • step (a2) is carried out in the presence of at least one demulsifier.
  • stage (a1) and stage (a2) are carried out in the presence of at least one demulsifier.
  • the demulsifiers used in step (a1) and in step (a2) may be the same or different. Preferably, however, the same demulsifier or demulsifiers are used in step (a1) as in step (a2).
  • demulsifier is used in the context of the present invention synonymous with "phase separation agent” and denotes an aid which accelerates the separation of the organic phase and the aqueous phase and / or improves the quality of the phase separation. Without intending to be limited, there is the notion that the demulsifiers act as a surfactant and thus alter the rate of formation of an, i. H. affect the reduced interface between the aqueous and organic phases. Demulsifiers are also referred to in the art as emulsion breakers or emulsion release agents. Although demulsifiers known from the prior art are in principle also suitable for the present invention, this does not mean that the aqueous phases and organic phases in all cases form a (stable) emulsion.
  • the term "in the presence of at least one demulsifier” means that at least one demulsifier is present in at least one sub-step of step (a1) and / or (a2) It is preferred if the demulsifier is mixed in the organic phase (N -ein) and the aqueous phase (W-a) in the respective stage (a1) or (a2) is present, since such a good Set distribution at the interface between the two phases. If a mixing apparatus and then a phase separation apparatus is used in stage (a1) or stage (a2), then an addition of the demulsifier or demulsifiers is thus preferably carried out in the mixing apparatus, since the phase separation apparatus alone does not provide sufficient mixing.
  • the demulsifier (D) used are preferably amphiphilic compounds.
  • Amphiphilic compounds are compounds having at least one hydrophilic and at least one hydrophobic molecular portion, wherein a portion may be a functional group, a comonomer, an end group or a block of a block copolymer.
  • Corresponding amphiphilic compounds are known to the person skilled in the art.
  • Suitable demulsifiers (D) can have different modes of operation. In particular, the demulsifiers (D) can stabilize the reverse dispersion direction, alter wetting properties of solids, or displace other compounds that act as emulsifiers from the interface, but have less stabilizing effect than these.
  • the demulsifiers (D) are used in the context of the present invention preferably in an amount of 0.1 to 1000 ppm, in particular from 1 to 200 ppm, particularly preferably from 1 to 100 ppm, very particularly preferably from 2 to 60 ppm, in each case based to the entire weight amount W1 -a or W2-one.
  • the amount by weight of the demulsifier is here the total amount by weight of the aqueous phase used W1 -ein or W2- a counted.
  • Amphiphilic anionic copolymers are preferred as the demulsifier (D).
  • the content of monomeric units containing anionic groups is preferably from 0.1 to 5% by weight, based on the weight of the copolymer.
  • anionic groups carboxylate groups are preferably used.
  • the demulsifiers (D) are particularly preferably substantially water-soluble, in particular water-soluble.
  • Demulsifiers (D) are essentially water-soluble if they are either completely water-soluble or have at most a slight turbidity at 10% by weight in distilled water. The use of water-soluble demulsifiers prevents them from entering the product. Rather, the demulsifiers are then separated in the context of the inventive method with the aqueous phase.
  • Preferred amphiphilic anionic copolymers have a number average molecular weight of 5,000 to 20,000 g / mol. Preferred amphiphilic anionic copolymers also have a K value according to ISO 1628-1 (1% by weight of dry matter in distilled water) of from 25 to 50. Corresponding amphiphilic anionic copolymers are known per se to the person skilled in the art. They are in particular obtainable by copolymerization of acrylic acid and / or maleic acid with hydrophilic monomer units, for example vinyl monomers or olefins.
  • suitable demulsifiers (D) are made by the person skilled in the art on the basis of the following property profile: suitable demulsifiers are effective in low concentrations, in particular in the range from 1 to 100 ppm; they are chemically inert; they do not interfere with the product, for example because they are not wastewater relevant, or do not get there.
  • Copolymers containing maleic acid units, in particular copolymers based on maleic acid and at least one olefin, are particularly preferred as demulsifier (D).
  • the process according to the invention comprises further stages of working up the aqueous phases W1 -res and W2 res resulting from the process.
  • the aqueous phase (W1-res) is subjected to the following further work-up steps: (b) optionally removal of organic constituents from at least part of the aqueous phase (W1-res) obtained in step (a) by stripping, preferably by steam, ( c) removal of organic compounds from at least part of the aqueous phase (W1-res) resulting from stage (a) or stage (b) by thermal and / or oxidative degradation,
  • step (d) distillative depletion of ammonia from at least part of the aqueous phase resulting from step (c), and
  • step (e) optionally supplying at least a portion of the aqueous phase resulting from step (d) to a biological wastewater treatment.
  • the aqueous phase (W2-res) is subjected to the following further processing steps: (b) optionally removal of organic constituents from at least one Part of the aqueous phase (W2-res) obtained in step (a) by stripping, preferably with steam,
  • step (D) optionally distillative depletion of ammonia from at least a portion of the resulting from step (c) aqueous phase or aqueous phases, and
  • step (e) optionally supplying at least a portion of the aqueous phase resulting from step (d) to a biological wastewater treatment
  • aqueous phase (W1-res) resulting from stage (a) or stage (b) is not subjected to thermal and / or oxidative degradation.
  • Step (b) In a preferred embodiment, according to step (b), the removal of organic constituents from at least part of the aqueous phase or aqueous phases obtained in step (a) is carried out by stripping.
  • Stripping is the removal of certain volatile constituents from liquids by the passage of gases (nitrogen, water vapor, etc.) to understand, said components are converted into the gas phase or be discharged with the gas phase from the liquid.
  • the stripping is carried out in the context of the present invention with water vapor.
  • the stripping is preferably carried out in a stripping column, the organic constituents, in particular benzene and nitrobenzene, being separated off via the top.
  • the stripping column is preferably a tubular device with internals for the intensive mass transfer of gaseous and liquid phase.
  • the liquid is passed in countercurrent, that is, against the flow direction of the gas through the stripping column.
  • Corresponding processes and columns are known to the person skilled in the art and are described by way of example. in W. Meier, Sulzer, columns for rectification and absorption, in: Technical Review Sulzer, 2 (1979), page 49 ff, described.
  • Preferred methods are, for example, stripping in a column, preferably with random beds of packing, with structured packing or with mass transfer trays such as e.g. Sieve trays, bubble trays, tunnel floors or Thormannböden is filled.
  • the stripping according to step (b) is carried out at an absolute pressure of 0.1 to 10 bar, in particular 1 to 5 bar and a temperature of 35 to 180 ° C, in particular at 100 to 160 ° C.
  • stage (b) The condensate obtained in stage (b) and containing the starting aromatic compound and the aromatic nitro compound and non-aromatic organic compounds is then fed to a phase separator, the organic phase being preferably recycled to the laundry in step (a) and the aqueous phase again step (b) is supplied.
  • the steam obtained from the top of the stripping column including the organic components is used as a heat transferer in step (d) and the resulting condensate fed to a phase separator, wherein the organic phase is preferably recycled to the laundry in step (a) and preferably recirculating the aqueous phase to step (b).
  • step (d) a faultless function of stage (b) is desirable.
  • step (b) an alkaline wastewater is preferably obtained which contains benzene only in concentrations of at most 30 ppm, in particular not more than 5 ppm, and nitrobenzene in concentrations of at most 50 ppm, in particular not more than 20 ppm.
  • stage (a) or stage (b) the removal of organic compounds from at least part of the aqueous phase or aqueous phases resulting from stage (a) or stage (b) takes place within the scope of stage (c) by thermal and / or oxidative degradation.
  • thermolysis The removal of organic compounds from at least part of the aqueous phase or aqueous phases resulting from stage (a) or stage (b) by thermal degradation is referred to below as thermolysis.
  • the degradation takes place oxidatively, in particular by ozone (ozonolysis).
  • the effluent from stage (a) or stage (b) which is still laden with organic salts of the nitrohydroxyaromatics, excluding oxygen is at temperatures of 150 to 500 ° C, preferably 250 to 350 ° C, more preferably 250 to 300 ° C heated under pressure. It is also possible to heat the wastewater under an inert gas atmosphere or under an inert gas pre-pressure of, for example, 0.1 to 100 bar.
  • inert gases are e.g. Nitrogen and / or argon suitable.
  • absolute pressures in the range from 50 to 350 bar, more preferably 50 to 200 bar, very particularly preferably 70 to 130 bar, are preferred when heating the waste water.
  • the heating of the alkaline waste water and thermal pressure decomposition of the nitrophenols is usually carried out for 5 to 120 minutes, preferably 20 to 45 minutes.
  • the waste water is in pressure vessels at a temperature of 150 ° C to 350 ° C, preferably 250 ° C to 300 ° C, a pressure of 10 bar to 200 bar, preferably 70 bar to 150 bar and a pH of the effluent of 8 thermolyzed to 14, preferably 9 to 13.
  • pressure vessel all known from the prior art pressure vessel can be used, which are designed for the above temperatures and pressures.
  • tube reactors and autoclaves connected in cascade are suitable for a continuous process procedure.
  • the wastewater is pumped by a heat pump.
  • promoted exchanger for example, in which it is preheated to 280 ° C. Subsequently, the preheated wastewater is heated by direct injection of 100 bar steam or by indirect heating to 300 ° C. After a residence time of 20 minutes to 60 minutes, the reaction solution is cooled and relaxed in countercurrent with the feed.
  • step (c) is carried out as a thermolysis in the absence of an inert gas at an absolute pressure of 50 to 350 bar and a temperature of 150 to 500 ° C.
  • the removal of organic compounds, in particular nitrophenols takes place from at least part of the aqueous phase or aqueous phases resulting from stage (a) or stage (b) by oxidative degradation, preferably by ozonolysis.
  • Processes for the ozonolysis of wastewater from the nitration of aromatic compounds are also known to the person skilled in the art.
  • the ozonolysis is preferably continuously in a cascade of reactors connected in countercurrent are done. In this way, the ozone is so completely removed from the gas stream that you can usually do without a Restozonvernichtung.
  • Corresponding methods are described in particular in EP 0 378 994 A1, the content of which is hereby incorporated by reference in its entirety.
  • the content of nitrophenols in the wastewater is preferably at most 100 ppm, especially at most 30 ppm.
  • the content of ammonia in the waste water resulting from step (c) is usually from 100 to 3000 ppm, especially from 500 to 1500 ppm.
  • the content of nitrate in the wastewater resulting from step (c) is usually from 5 to 500 ppm, especially from 20 to 300 ppm.
  • the content of nitrite in the waste water resulting from step (c) is usually from 200 to 10,000 ppm, especially from 500 to 3000 ppm.
  • the content of organically bound nitrogen (atomic calculated) in the wastewater resulting from step (c) is usually from 5 to 200 ppm, especially from 5 to 40 ppm.
  • the distillative removal of ammonia takes place from the aqueous phase or aqueous phases resulting from stage (b) or stage (c).
  • the distillation of the aqueous phase (s) can be carried out by methods known per se.
  • the distillation according to step (d) is carried out at an absolute pressure of 0.1 to 10 bar, in particular 1 to 5 bar, wherein said pressure is present at the top of the distillation apparatus.
  • the distillative removal of ammonia according to step (d) is carried out at a temperature of 80 to 140 ° C, wherein said temperature is present at the top of the distillation apparatus.
  • the content of ammonia in the aqueous phase after step (d) is at most 100 ppm, in particular at most 20 ppm, particularly preferably at most 10 ppm.
  • aqueous phase (s) is preferably implemented at temperatures of 50 to 160 ° C and absolute pressures of 0.1 to 10 bar, in particular 1 to 5 bar.
  • the distillative depletion of ammonia can be carried out in known apparatuses.
  • the evaporation of ammonia is suitably carried out in a distillation column.
  • the column can be used with unstructured packages known to the person skilled in the art, e.g. random beds of packing, with structured packing or with mass transfer trays such as e.g. Be filled sieve trays, bubble trays, tunnel floors or Thormann floors.
  • unstructured or structured packings and mass transfer trays are combined with one another, so that an optimum separation effect is achieved.
  • the heat input into the distillation column is preferably effected by a coupled evaporator. In this way, step (d) can be integrated into the process in a particularly energetically favorable manner.
  • An evaporator in process engineering is an apparatus for converting a liquid to its vapor state. To evaporate the liquid, the supply of thermal energy is required. Evaporators therefore usually consist of a surface through which heat from a heat transfer medium, preferably a liquid, is transferred to the liquid to be evaporated. In the context of the present invention, preference is given to evaporators which transfer the required heat indirectly (no direct contact between the heat carrier and the liquid to be evaporated). According to evaporators are known in the art. Suitable evaporators are in particular natural circulation evaporators, forced circulation evaporators, Kettle evaporators, steam boilers, falling film evaporators and thin-film evaporators. Particularly suitable are evaporators based on a tube bundle. Particularly preferred are falling film evaporators.
  • the vapor phase resulting from stage (b) is preferably used for indirect heat transfer in stage (d).
  • the vapor phase resulting from stage (b) is introduced as heat transfer medium into an evaporator within the scope of stage (d).
  • the heat exchanger is returned after the step (d) at least partially in the step (a).
  • the heat transfer medium is subjected to a phase separation following the step (d) to obtain an organic phase and an aqueous phase, the resulting organic phase being recycled to the step (a).
  • the resulting aqueous phase is fed to step (b).
  • the effluent obtained by the process according to the invention, completely or partially freed of ammonia wastewater can directly, d. H. without further separation steps, a biological wastewater treatment, in particular a sewage treatment plant, are supplied.
  • the overhead product containing ammonia which is obtained in this case is preferably condensed by methods known per se to those skilled in the art and is preferably recycled partly as condensate return to the distillation column within the scope of step (d) and partly fed to a further work-up, preferably a combustion. Uncondensed components can be fed to a further exhaust gas treatment.
  • stage (e) it is preferable to supply at least a portion of the aqueous phase resulting from stage (d) to a biological wastewater treatment stage.
  • Example 1 Stage a1, Sub-stage 1: 21 t / h of crude nitrobenzene from the nitration of benzene containing 1000 ppm by weight of picric acid and 2300 ppm by weight of dinitrophenol were mixed with 0.19 t / h of 25% sodium hydroxide solution and the aqueous Phase from stage a1, sub-step 2 and intensive mixing in a stirred tank at 130 min "1.
  • Stage a1, Sub-step 2 After subsequent phase separation in a subsequent phase separation apparatus, the organic phase is from stage a1, sub-stage 1 at 8 t / h NaOH alkaline condensate from the vacuum distillation of sulfuric acid concentration and 0.001% by weight of the demulsifier D1, based on the amount by weight of nitrobenzene, and again intensively mixed at 100 min -1 After phase separation, the aqueous phase was returned to stage a1, substep 1. The organic phase was fed to stage a2 Stage from stage a1, sub-step 2 contained 6000 ppm by weight nitrophenolates.
  • Stage a2 The organic phase from stage a1, sub-step 2 was admixed with 6 t / h of wastewater from aniline production (0.2% by weight of mononitrobenzene and 200 ppm of ammonia, pH 9) and also 0.001% by weight of demulsifier D1 mixing a stirred tank at 90 min is "1. After subsequent phase separation in a subsequent phase separation apparatus 21 h mononitrobenzene (content below the detection limit) were t / obtained, which was free of nitrophenols. the effluent from stage a2 contained less than 10 ppm by weight Nitrophenolate A thermolytic or ozonolytic wastewater treatment of the aqueous phase can be omitted.
  • the demulsifier D1 was an amphiphilic anionic copolymer containing olefin and maleic acid units (Na salt) as a 25% strength by weight aqueous solution having a pH according to DIN 19268 at 23 ° C. of 11, an iodine number according to DIN EN 1557 at 23 ° C of 2 and a K value according to ISO 1628-1 as 1 wt .-% solution in dist. Water of 35 used. The content of sodium maleate, calculated as maleic acid, in the copolymer, determined by HPLC, was 0.3% by weight.
  • Na salt olefin and maleic acid units

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé d'épuration de composés nitroaromatiques bruts qui proviennent de la nitruration de composés aromatiques, comprenant les étapes de lavage suivantes (a1) et (a2), chacune des étapes (a1) et (a2) étant exécutée une ou plusieurs fois successivement : (a1) mettre en contact le composé nitroaromatique brut (N1-ein) avec une première phase aqueuse (W1-ein) comprenant au moins une base (B), puis séparer les phases en donnant une phase organique (N1-res) et une phase aqueuse (W1-res) ; puis (a2) mettre en contact de la phase organique (N1-res) obtenue dans l'étape (a1) avec une deuxième phase aqueuse (W2-ein), puis séparer les phases en donnant une phase organique épurée (N2-res) et au moins une phase aqueuse (W2-res), la phase aqueuse utilisée (W2-ein) présentant un pH de 6 à 9.
PCT/EP2012/064368 2011-08-09 2012-07-23 Procédé d'épuration des eaux usées provenant du traitement de composés nitroaromatiques bruts WO2013020798A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP11176891 2011-08-09
EP11176891.7 2011-08-09

Publications (1)

Publication Number Publication Date
WO2013020798A1 true WO2013020798A1 (fr) 2013-02-14

Family

ID=46545401

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2012/064368 WO2013020798A1 (fr) 2011-08-09 2012-07-23 Procédé d'épuration des eaux usées provenant du traitement de composés nitroaromatiques bruts

Country Status (1)

Country Link
WO (1) WO2013020798A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8697921B2 (en) 2011-08-09 2014-04-15 Basf Se Process for purifying wastewaters from the workup of crude aromatic nitro compounds
CN103936207A (zh) * 2014-05-15 2014-07-23 山东大学 一种处理硝基苯酚废水的方法
WO2016198921A1 (fr) * 2015-06-12 2016-12-15 Noram International Limited Procédé de purification de composés aromatiques nitrés provenant d'un procédé de nitration

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0378994A1 (fr) 1989-01-14 1990-07-25 BASF Aktiengesellschaft Procédé pour la purification d'eaux usées contenant des aromates nitrés
EP0436443A2 (fr) 1990-01-04 1991-07-10 Nrm International Technologies C.V. Procédé de nitration
EP0953546A2 (fr) 1998-04-08 1999-11-03 Basf Aktiengesellschaft Procédé pour dégrader les composés nitroaromatiques dans les eaux usées
EP1593654A1 (fr) 2004-04-10 2005-11-09 Bayer MaterialScience AG Procédé de traitement d'eaux usées contenant des composés nitro-aromatiques
DE102006013579B3 (de) * 2006-03-22 2007-08-23 Plinke Gmbh Verfahren zur Reduzierung des Abwassers und Optimierung der Abwasserqualität bei der Herstellung von DNT
WO2009027416A1 (fr) 2007-08-30 2009-03-05 Basf Se Procédé de traitement des eaux usées de nitration
WO2011021057A1 (fr) * 2009-08-18 2011-02-24 Noram International Limited Système de lavage pour des composés nitroaromatiques

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0378994A1 (fr) 1989-01-14 1990-07-25 BASF Aktiengesellschaft Procédé pour la purification d'eaux usées contenant des aromates nitrés
EP0436443A2 (fr) 1990-01-04 1991-07-10 Nrm International Technologies C.V. Procédé de nitration
EP0953546A2 (fr) 1998-04-08 1999-11-03 Basf Aktiengesellschaft Procédé pour dégrader les composés nitroaromatiques dans les eaux usées
EP1593654A1 (fr) 2004-04-10 2005-11-09 Bayer MaterialScience AG Procédé de traitement d'eaux usées contenant des composés nitro-aromatiques
DE102006013579B3 (de) * 2006-03-22 2007-08-23 Plinke Gmbh Verfahren zur Reduzierung des Abwassers und Optimierung der Abwasserqualität bei der Herstellung von DNT
WO2009027416A1 (fr) 2007-08-30 2009-03-05 Basf Se Procédé de traitement des eaux usées de nitration
WO2011021057A1 (fr) * 2009-08-18 2011-02-24 Noram International Limited Système de lavage pour des composés nitroaromatiques

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
"Ullmann's Encyclopedia of Industrial Chemistry", 2005, WILEY-VCH VERLAG GMBH & CO. KGAA
KIRK-OTHMER: "Encyclopedia of Chemical Technology, ''Nitrobenzene and Nitrotoluenes", 14 October 2005
W. MEIER, SULZER: "Kolonnen für Rektifikation und Absorption", TECHNISCHE RUNDSCHAU SULZER, vol. 2, 1979, pages 49, XP055262964

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8697921B2 (en) 2011-08-09 2014-04-15 Basf Se Process for purifying wastewaters from the workup of crude aromatic nitro compounds
CN103936207A (zh) * 2014-05-15 2014-07-23 山东大学 一种处理硝基苯酚废水的方法
CN103936207B (zh) * 2014-05-15 2015-06-10 山东大学 一种处理硝基苯酚废水的方法
WO2016198921A1 (fr) * 2015-06-12 2016-12-15 Noram International Limited Procédé de purification de composés aromatiques nitrés provenant d'un procédé de nitration
US10155719B2 (en) 2015-06-12 2018-12-18 Noram International Limited Method of purifying nitrated aromatic compounds from a nitration process
CZ308420B6 (cs) * 2015-06-12 2020-08-12 Noram International Limited Způsob čištění nitrovaných aromatických sloučenin z procesu nitrace

Similar Documents

Publication Publication Date Title
EP2603461B1 (fr) Procédé d'épuration des eaux résiduaires issues du traitement de composés nitroaromatiques bruts
EP1593654B1 (fr) Procédé de traitement d'eaux usées contenant des composés nitro-aromatiques
EP1496043A1 (fr) Procédé de traitement des eaux usées du procédé de fabrication de dinitrotoluène
EP2877441B2 (fr) Procédé de fabrication de nitrobenzole par nitrification adiabate
WO2009027416A1 (fr) Procédé de traitement des eaux usées de nitration
EP2877443B1 (fr) Procede destine à la fabrication de benzol nitrique par nitrification d'adiabate
EP1493730B1 (fr) Procédé de traitement des sous-produits de la production de dinitrotoluène
EP2742003B1 (fr) Procédé pour épurer des eaux usées issues du traitement de composés nitroaromatiques bruts
EP1993990B1 (fr) Procede de separation par distillation de dinitrotoluene d'une eau residuelle d'un procede de fabrication de dinitrotoluene par nitration de toluene avec de l'acide nitrosulfurique
EP2841412B1 (fr) Procédé destiné au lavage du dinitrotoluol
EP2877442B1 (fr) Procédé de preparation de nitrobenzène par nitrification adiabatique
WO2013020798A1 (fr) Procédé d'épuration des eaux usées provenant du traitement de composés nitroaromatiques bruts
EP2986563B1 (fr) Procédé de traitement d'eaux usées issues de la fabrication de nitrobenzène
US8697921B2 (en) Process for purifying wastewaters from the workup of crude aromatic nitro compounds
EP2986562B1 (fr) Procédé de traitement d'eaux usées issues de la fabrication de nitrobenzène
US20130041188A1 (en) Process for purifying wastewaters from the workup of crude aromatic nitro compounds
DE102020002434B4 (de) Verfahren zur Reduzierung des Wasserstoffperoxid-Verbrauchs bei der Reinigung von mit organischen Verbindungen verunreinigter Abfallschwefelsäure durch oxidative Behandlung
DE102020002443B4 (de) Verfahren zur Reduzierung des Salpetersäureverbrauchs bei der Reinigung von mit organischen Verbindungen verunreinigter Abfallschwefelsäure durch oxidative Behandlung
EP3592727B1 (fr) Procédé de fabrication de nitrobenzène
DE102018217955B4 (de) Verfahren zur Aufarbeitung von Mischsäure und Abwasser aus der Nitrierung von Aromaten sowie Vorrichtung zur Durchführung des Verfahrens

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12737298

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12737298

Country of ref document: EP

Kind code of ref document: A1