CN112912168B - Improved process and plant for the production of oximes - Google Patents
Improved process and plant for the production of oximes Download PDFInfo
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- CN112912168B CN112912168B CN201980068278.3A CN201980068278A CN112912168B CN 112912168 B CN112912168 B CN 112912168B CN 201980068278 A CN201980068278 A CN 201980068278A CN 112912168 B CN112912168 B CN 112912168B
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C249/00—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton
- C07C249/04—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton of oximes
- C07C249/08—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton of oximes by reaction of hydroxylamines with carbonyl compounds
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C251/00—Compounds containing nitrogen atoms doubly-bound to a carbon skeleton
- C07C251/32—Oximes
- C07C251/34—Oximes with oxygen atoms of oxyimino groups bound to hydrogen atoms or to carbon atoms of unsubstituted hydrocarbon radicals
- C07C251/44—Oximes with oxygen atoms of oxyimino groups bound to hydrogen atoms or to carbon atoms of unsubstituted hydrocarbon radicals with the carbon atom of at least one of the oxyimino groups being part of a ring other than a six-membered aromatic ring
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Abstract
The present invention provides a method for producing an oxime, comprising: a. converting an aldehyde or ketone into an oxime by a chemical reaction at a temperature of 15 ℃ to 115 ℃ to obtain a reaction mixture comprising the oxime formed; b. recovering the formed oxime from the reaction mixture; c. producing a first aqueous phase containing phosphate ions; d. reducing the phosphate ion content of the first aqueous phase, thereby forming a second aqueous phase; discharging the second aqueous phase, wherein the reduction of the content of phosphate ions in the first aqueous phase is achieved by: 1) forming a salt having a molar ratio of N to Mg to P of about 1:1: 1; and 2) separating from the second aqueous phase a salt having a molar ratio of N: Mg: P of about 1:1: 1; also provided is a fertilizer product comprising magnesium ammonium phosphate hexahydrate obtained therefrom; a cyclohexanone oxime obtained therefrom; and a chemical plant suitable for producing an oxime.
Description
Technical Field
The present invention relates to a method and plant for removing phosphate from wastewater originating from oxime production.
Background
Oximes are typically produced by the reaction of hydroxylamine with an aldehyde or ketone. Examples of oximes are butanone oxime, cyclohexanone oxime and cyclododecanone oxime, which are prepared by condensation of hydroxylamine with butanone, cyclohexanone and cyclododecanone, respectively.
Butanone oxime (also known as methyl ethyl ketoxime) is used in particular in the paint industry to inhibit the formation of skin on the paint prior to its use.
Cyclododecanone oxime is mainly consumed as a precursor of laurolactam, which is a precursor of polyamide-12 (also referred to as nylon-12).
Cyclohexanone oxime is an intermediate in the production of compounds, especially caprolactam. This monomer is commonly used in the production of polyamide-6 (also known as nylon-6).
One process for producing oximes is based on the selective reaction of cyclohexanone, ammonia and hydrogen peroxide in the presence of a catalyst. In particular, catalysts based on titanium silicalite are very suitable for this so-called ammoximation reaction. Processes for producing such catalysts are known in the art (see, e.g., US 4,410,501 and US 9,896,343). By using NH in the liquid phase3And H2O2Catalytic processes for the ammoximation of cyclohexanone to cyclohexanone oxime are also known in the art (see e.g. US 4,794,198, EP 1674448 and US 7,408,080).
In the case of cyclohexanone oxime formation by ammoximation, the chemical reaction that takes place is represented as follows:
reaction 1) preparation of cyclohexanone oxime in the cyclohexanone formation zone:
typically, the cyclohexanone oxime formed is purified and recovered by extraction, (caustic) water washing and distillation steps.
Oxime production processes based on ammoximation produce large amounts of waste water containing significant amounts of organic and inorganic components. The main sources of water are dilution water originating from the starting material (e.g. aqueous hydrogen peroxide) and water chemically formed in the ammoximation process (see e.g. reaction 1). A typical cyclohexanone ammoximation process produces at least 2.5 tons of wastewater per ton of cyclohexanone oxime produced. Usually, this wastewater is discharged to a biochemical wastewater treatment plant.
Several patents relating to the removal of organic components from the wastewater of cyclohexanone ammoximation processes have been granted. For example, CN 103214044, CN 101618919 and CN 101734825 describe methods of oxidizing organic substances in wastewater from ammoximation plants to improve biodegradability before the wastewater is charged into biochemical wastewater treatment plants. However, to the best of the inventors' knowledge, the prior art has never disclosed the removal of phosphorus from the waste water of ammoximation plants, which phosphorus may be present in inorganic form, for example in the form of phosphate, or in organic form, for example in the form of trioctyl phosphate. The phosphorus discharged from the process with the waste water may originate from raw materials, such as aqueous hydrogen peroxide, and/or from auxiliary materials used in the process.
In CN 107986987, an alcohol, e.g. cyclohexanol, based ammoximation process has been disclosed, which is a variant of the above mentioned aldehyde or ketone based ammoximation process. Without being bound by theory, it is hypothesized that in this process the alcohol is first converted to an aldehyde or ketone, which is then converted to an oxime. The addition of a pre-oxidation step makes this alcohol-based ammoximation process only an extended version of the aldehyde or ketone-based ammoximation process. Although the alcohol ammoximation process has not been commercialized, the process will produce a wastewater stream containing at least the same amount of phosphorus because the hydrogen peroxide consumption of this alcohol ammoximation variant is even higher than that of traditional aldehyde or ketone based ammoximation processes.
In another method, oximes are prepared by reacting hydroxylammonium phosphate buffer with aldehydes or ketones in the presence of a solvent. The hydroxylammonium phosphate solution is obtained by selective hydrogenation of nitrate ions or nitrogen oxides in an aqueous solution containing phosphoric acid. Such a method for producing an oxime is generally referred to as
Method is and is
And (4) permitted.
The method is mainly applied to the production of cyclohexanone oxime.
In the case of hydroxylamine formation starting from a solution of phosphoric acid and nitrate, the chemical reaction that takes place is represented as follows:
reaction 2) preparation of hydroxylamine in the hydroxylamine formation region:
2H3PO4+NO3 -+3H2→NH3OH++2H2PO4 -+2H2O
the resulting mixture of the first reaction is a phosphate-containing acidic aqueous solution comprising a suspension of solid catalyst particles in a hydroxylamine solution.
In that
Is/are as follows
In the cyclohexanone oxime process, the hydroxylamine solution obtained after removal of the catalyst is contacted with an organic liquid comprising cyclohexanone and a solvent. Thus cyclohexanone reacts with hydroxylamine to form cyclohexanone oxime by the reaction:
reaction 3) preparation of cyclohexanone oxime in the cyclohexanone oxime forming zone:
after separation of the organic liquid containing the cyclohexanone oxime formed from the inorganic liquid containing phosphoric acid, fresh nitrate or nitrogen oxides are added to the inorganic liquid containing phosphoric acid and subsequently recycled to the hydroxylamine formation zone.
The separated organic liquid containing the formed cyclohexanone oxime is washed with water and cyclohexanone oxime is recovered from the washed organic liquid by distillation.
Discharged from the process after steam stripping (steam stripping)
All water chemically formed in the process (see e.g. reaction 2) and reaction 3)) and water added to the process (e.g. water used for washing the separated organic liquid containing the formed cyclohexanone oxime). Typically, a
The cyclohexanone oxime process discharges about 1.5 tons of waste water per ton of cyclohexanone oxime produced. This wastewater contains only trace amounts of organic components and a small amount of inorganic components including some phosphate. Usually, this wastewater is discharged to a biochemical wastewater treatment plant.
Phosphorus is a nutrient required for plant survival and is a limiting factor for plant growth in many aqueous ecosystems. An excessive supply of phosphorus, for example due to discharge of wastewater containing phosphate originating from the cyclohexanone oxime production process, may cause excessive growth of plants and algae. The term eutrophic or hyper-eutrophic is generally used to describe this process. As early as the 70's of the last century, the Organization of Economic collaboration and Development (abbreviated as OECD) gave the following definition of the eutrophication process: "eutrophication refers to the enrichment of water with nutrient salts, which cause structural changes in the ecosystem, such as: increased production of algae and aquatic plants, reduced fish species, general deterioration of water quality, and other effects that reduce and prevent use.
Discharge standards have been tightened by regulatory authorities worldwide to avoid problems associated with eutrophication of water ecosystem.
One method for reducing phosphorus levels in discharged water for use in wastewater treatment plants is to direct phosphorus into sewage sludge or biosolids, which is often incinerated or applied to the ground.
Another method applied for reducing the phosphorus content of the waste water before discharge is based on adding sufficient calcium (for example in the form of limestone) to react with the phosphorus in the waste water, forming precipitates of, for example, calcium hydroxyapatite, brushite or dicalcium phosphate dihydrate, these salts being salts with low solubility in water.
Another method used to reduce the phosphorus content in wastewater is based on the formation of slightly water-soluble aluminum hydroxyphosphates. For this reason, aluminum-containing materials such as aluminum sulfate, alum (e.g., burkeite, alumite, and ammonioalum), or clay are added.
Yet another phosphorus reduction method is based on the precipitation of iron phosphate.
Wastewater treatment processes employing one of the above processes (or a combination thereof) often face the problem of the detrimental formation of phosphate minerals in pipelines, heat exchangers and tanks due to the high levels of phosphate produced during anaerobic decomposition of solids. In addition, the above method necessarily generates a large amount of sludge due to the use of a large amount of chemicals and the necessity of cumbersome post-treatment. Furthermore, in general, the materials produced do not have any economic value: the most significant costs are associated with disposal or other post-processing methods. Last but not least, these methods often fail to meet the required phosphate discharge standards.
Therefore, the prior art method for treating wastewater derived from the cyclohexanone oxime production process is disadvantageous in that a complicated process is required and there are many problems in terms of performance, operation control, treatment cost and achievement of required removal efficiency.
Therefore, there is a need to develop a method for removing phosphorus with high efficiency, which is economically dominant, and easy and convenient to operate, and produces phosphate-containing materials having economic value.
In view of the above, it is an object of the present invention to provide a novel process for dephosphorization of wastewater derived from an oxime production process, which process can effectively remove phosphorus so as to be below (undercut) applicable discharge standards.
Another object of the present invention is to provide a novel dephosphorization method for wastewater derived from an oxime production process, which lacks problems in terms of performance and operational control, such as the harmful formation of phosphate minerals on the surfaces of the applied equipment and piping.
Another object of the present invention is to provide a novel dephosphorization method for wastewater derived from an oxime production process, which is more economical than the existing methods.
It is another object of the present invention to provide a novel dephosphorization process for wastewater from an oxime production process which results in phosphate containing material of economic value.
Still another object of the present invention is to provide a novel dephosphorization method for wastewater derived from an oxime production process, which is more environmentally friendly than the methods known in the art.
Today, processes for producing oximes having phosphorus in the waste water, such as processes based on the selective reaction of aldehydes or ketones, ammonia and hydrogen peroxide in the presence of a catalyst or those based on the reaction of buffered hydroxylammonium phosphate solutions with aldehydes or ketones in the presence of a solvent, wherein the hydroxylammonium phosphate solution is obtained by selective hydrogenation of nitrate ions or nitrogen oxides in an aqueous solution containing phosphoric acid, require a novel dephosphorization process of the waste water thereof due to strict emission standards of phosphorus.
In addition, since phosphorus is becoming scarce, it is necessary to recover phosphorus from wastewater and reuse the recovered phosphorus.
Currently oxime producers advantageously use the following methods to produce oximes: processes based on the selective reaction of an aldehyde or ketone, ammonia and hydrogen peroxide in the presence of a catalyst; or a process based on the reaction of a buffered hydroxylammonium phosphate solution with an aldehyde or ketone in the presence of a solvent, wherein the hydroxylammonium phosphate solution is obtained by selective hydrogenation of nitrate ions or nitrogen oxides in an aqueous solution containing phosphoric acid. However, problems arise because the prior art is not able to meet emissions requirements.
The inventors have found a process for the dephosphorization of waste water resulting from a process for the production of oximes based on the selective reaction of an aldehyde or ketone, ammonia and hydrogen peroxide in the presence of a catalyst that is significantly improved; or on the reaction of a buffered hydroxylammonium phosphate solution with an aldehyde or ketone in the presence of a solvent, wherein the hydroxylammonium phosphate solution is obtained by selective hydrogenation of nitrate ions or nitrogen oxides in an aqueous phosphoric acid solution.
They have developed an improved process for producing oximes based on the selective reaction of an aldehyde or ketone, ammonia and hydrogen peroxide in the presence of a catalyst; or on the reaction of a buffered hydroxylammonium phosphate solution with an aldehyde or ketone in the presence of a solvent, wherein the hydroxylammonium phosphate solution is obtained by selective hydrogenation of nitrate ions or nitrogen oxides in an aqueous phosphoric acid solution. More specifically, the present invention provides an improved method for producing an oxime, comprising:
a. converting an aldehyde or ketone into an oxime by a chemical reaction at a temperature of 15 ℃ to 115 ℃ to obtain a reaction mixture comprising the oxime formed;
b. recovering the formed oxime from the reaction mixture;
c. producing a first aqueous phase containing phosphate ions;
d. reducing the phosphate ion content of the first aqueous phase, thereby forming a second aqueous phase; and
e. (ii) discharging the second aqueous phase,
wherein the reduction of the content of phosphate ions in the first aqueous phase is achieved by:
1) forming a salt having a molar ratio of N to Mg to P of about 1:1: 1; and
2) separating the salt having a molar ratio of N: Mg: P of about 1:1:1 from the second aqueous phase.
As defined herein, a salt having a molar ratio of N: Mg: P of about 1:1:1 may be magnesium ammonium phosphate and/or various hydrates thereof. Non-limiting examples of magnesium ammonium phosphate hydrates include magnesium ammonium phosphate monohydrate (also commonly known as dimagnesite), magnesium ammonium phosphate tetrahydrate (also commonly known as schertelite), and magnesium ammonium phosphate hexahydrate (also commonly known as struvite).
As used herein, N, Mg and P are the symbols for the chemical elements nitrogen, magnesium, and phosphorus, respectively.
According to the invention, the salt formed, with a molar ratio of N: Mg: P of about 1:1:1, may be amorphous or crystalline.
The salt formed with a molar ratio of N: Mg: P of about 1:1:1 may also contain other compounds with a molar ratio of N: Mg: P other than about 1:1: 1.
The salt formed with a molar ratio of N: Mg: P of about 1:1:1 may consist of settled large size particles, non-settled fines, and combinations thereof.
The person skilled in the art is familiar with the separation of salts from aqueous phases. There are various techniques for removing fine and large size particles from an aqueous phase. This includes, for example, the use of various filtration and centrifugation techniques, which may be combined with various pretreatment techniques such as coagulation and sedimentation.
Industrial wastewater is often treated in biochemical wastewater treatment plants. A minimum amount of phosphate is required to promote the growth of bacteria and other organisms that treat the wastewater. In the case of a phosphate deficiency at the inlet, phosphate (e.g., in the form of phosphoric acid) should be added to the system. During the biochemical process in a biochemical wastewater treatment plant, phosphorus is introduced into biosolids (e.g., microorganisms). Sludge produced by biochemical wastewater treatment plants is rich in phosphorus. After separation of the sludge from the effluent, the effluent from the biochemical wastewater treatment plant is reduced in phosphorus. While it is common for the phosphate content in the inlet of a biochemical wastewater treatment plant to be in the range of 3 to 10mg/l (ppm), other biochemical wastewater treatment plants are operated outside this optimal concentration window.
The present inventors have realised that it would be advantageous to use the second aqueous phase as a phosphate source in a biochemical wastewater treatment plant, instead of feeding phosphate from an external source. This solution not only saves valuable compounds, such as for example phosphoric acid, but also enhances the rate of dephosphorization of the second aqueous phase.
According to a preferred embodiment of the method of the invention, the method further comprises:
f. reducing the phosphate ion content of the second aqueous phase, thereby forming a third aqueous phase; and
g. the third aqueous phase is discharged and,
wherein the reduction of the content of phosphate ions in the second aqueous phase is achieved by:
1) charging the second aqueous phase into a biochemical wastewater treatment plant, and
2) discharging the third aqueous phase from the biochemical wastewater treatment plant.
The effluent from the biochemical wastewater treatment plant comprises the third aqueous phase and may further contain solid matter such as, for example, sludge. This solid material is advantageously separated to a large extent from the third aqueous phase, whereby a solid matter-containing phase and a (almost) transparent third aqueous phase are formed.
Magnesium ammonium phosphate hexahydrate may be formed by the reaction:
Mg2++NH4 ++PO4 3-+6H2O→MgNH4PO4.6H2O
according to a preferred embodiment of the process of the invention, the salt having a molar ratio of N: Mg: P of about 1:1:1 is magnesium ammonium phosphate hexahydrate.
Preferably, the formation of magnesium ammonium phosphate hexahydrate is carried out at a pH value in the range of 6 to 14, more preferably 7 to 11 and most preferably 8 to 10. Mg as the pH increases2+And NH4+The concentration of ions is reduced and PO is4 3-The concentration of (a) is increased due to the greater availability (availabilitity) of orthophosphate at higher pH values.
Typically, in the process of the invention, the formation of a salt having a molar ratio of N: Mg: P of about 1:1:1 can be achieved by adjusting the pH of the first aqueous phase. The adjustment of the pH value can be achieved in different ways. Typically, the pH of the first aqueous phase can be adjusted by adding caustic (solution, solid or slurry), ammonia, or by mixing with a waste stream that provides the desired pH adjustment. Incinerator effluent streams containing sodium carbonate, sodium bicarbonate, sodium hydroxide and mixtures thereof are well suited for controlling pH. Such effluent streams may be solutions, solids, or slurries.
According to a preferred embodiment of the process of the invention, the salt formation is achieved by adjusting the pH of the first aqueous phase to between about 6 and 14.
According to a preferred embodiment of the process of the invention, the formation of salts is achieved by adding the effluent stream of the incinerator to the first aqueous phase.
The formation of a salt with a molar ratio of N: Mg: P of about 1:1:1, such as magnesium ammonium phosphate hexahydrate, followed by isolation of this salt, is a very efficient way of removing the phosphorus present in phosphate form. In the case where the phosphorus is present in organic form (organic phosphorus), for example in the form of trioctyl phosphate, a pretreatment step is required to convert the organic phosphorus into phosphate. Several methods are known for this transformation. A simple and very efficient process is based on hydrolysis under alkaline conditions: for this purpose, the pH of the organophosphorus-containing wastewater is increased to a value, for example, in the range of about 10 to about 14 by adding a base (e.g., NaOH). Both the temperature in the range of about ambient to boiling temperature and the residence time of at least 15 minutes are not particularly critical. For example, more than 99% of trioctyl phosphate in the wastewater is hydrolyzed to phosphate at a pH, temperature and residence time of at least 10.5, 40 ℃ and 10 hours, respectively.
Generally, in the process of the invention, the formation of a salt having a molar ratio of N: Mg: P of about 1:1:1 requires the presence of a sufficient concentration of magnesium ions. In case the concentration of magnesium ions in the first aqueous phase is insufficient, the concentration of magnesium ions can be increased in different ways. Typically, the concentration of magnesium ions in the first aqueous phase is increased by adding magnesium ions from an external source (e.g. magnesium-containing salts). In fact, any magnesium-containing salt can be added to meet this requirement. Particularly suitable for this purpose are salts comprising magnesium hydroxide, magnesium chloride and magnesium carbonate. These salts may be added as a solution, as a solid or as a slurry.
Preferably, the molar ratio of magnesium ions to phosphate ions is at least 1:1, more preferably 1.1:1, most preferably 1.25: 1. Higher ratios are even more preferred. However, a much higher ratio is not desirable because the cost of the magnesium salt is relatively high.
In one embodiment of the process of the present invention, the salt formation is achieved by adding a magnesium-containing salt to the first aqueous phase.
Formation of a salt with a molar ratio of N: Mg: P of about 1:1:1 requires the presence of a sufficient concentration of ammonium ions. Generally, ammonium ions are present in wastewater from a process for producing oxime. However, it may be desirable to increase the concentration of ammonium ions of the first aqueous phase by adding ammonium ions to enhance the degree of dephosphorization. In fact, the addition of ammonium from any source can overcome this deficiency. Particularly suitable for this purpose are ammonia or aqueous ammonia solutions, for example 25 wt.% aqueous ammonia.
Preferably, the molar ratio of ammonium ions to phosphate ions is at least 1:1, more preferably at least 1.5:1 and most preferably 2: 1. Even more preferred is a higher ratio of ammonium ion to phosphate ion molar ratio of more than 2: 1. However, much higher ratios are not desirable because of the limitations on the ammonia content of the wastewater effluent.
In one embodiment of the process of the present invention, the formation of the salt is achieved by adding ammonium ions to the first aqueous phase.
In a preferred embodiment of the process of the invention, the salt formation in step e.1) is achieved by achieving a molar ratio of magnesium ions to phosphate ions of at least 1.15:1 and a molar ratio of ammonium ions to phosphate ions of at least 1.5:1 in the first aqueous phase.
The addition of an ammonium salt (e.g. ammonium chloride or ammonium sulphate) in solution, in solid form or in slurry is very suitable for increasing the ammonium ion concentration of the first aqueous phase. The aqueous waste stream or purge of the ammonium sulphate crystallisation plant is extremely suitable for enhancing the ammonium ion concentration of the first aqueous phase. Such waste streams or purifications may also comprise other organic and inorganic impurities (e.g. originating from a caprolactam production process). The inorganic impurities include sodium ions derived from the caprolactam purification process. Organic impurities include caprolactam and its derivatives.
In one embodiment of the process of the invention, the formation of salts in step e.1) is achieved by adding a stream originating from an ammonium sulphate crystallization plant and comprising ammonium ions and at least one inorganic or organic impurity originating from a caprolactam production process to the first aqueous phase.
The process of the present invention advantageously achieves a reduction of the phosphorus content in the third aqueous phase compared to the first aqueous phase of at least 10 times, preferably 50 times, more preferably 100 times, most preferably 200 times. The final effluent of the process of the invention contains less than 1.5ppm, especially less than 1ppm, especially less than 0.5ppm of phosphorus.
An oxime is a compound belonging to the class of imines, having the divalent group-C ═ NOH. The oximes have the general formula R1R2C ═ NOH, where R1Is an organic side chain and R2May be hydrogen, form an aldoxime, or another organic group, form a ketoxime. Oximes can be obtained by the reaction of an aldehyde or ketone with hydroxylamine.
According to one embodiment of the process of the present invention, in the chemical reaction, the aldehyde or ketone is converted to an oxime with hydroxylamine.
According to another embodiment of the process of the present invention, the process for producing an oxime is an ammoximation process, wherein in step a. an aldehyde or ketone, ammonia and hydrogen peroxide are reacted in the presence of a catalyst; or a process wherein hydroxylamine is first formed by selective reduction of nitrate followed by reaction of the hydroxylamine formed with a ketocyclohexanone to form an oxime in step a.
All aldehydes or ketones can be converted to oximes with hydroxylamine. At present, the conversion of butanone, cyclohexanone and cyclododecanone into oximes is economically the most important.
According to one embodiment of the process of the present invention, the ketone is selected from butanone, cyclohexanone or cyclododecanone.
Oximes obtained by conversion of butanone, cyclohexanone and cyclododecanone with hydroxylamine are butanone oxime, cyclohexanone oxime and cyclododecanone oxime, respectively.
According to one embodiment of the process of the invention, the oxime formed is selected from butanone oxime, cyclohexanone oxime or cyclododecanone oxime. According to a preferred embodiment of the process of the invention, the ketone is cyclohexanone and the oxime formed is cyclohexanone oxime. Subsequently, the obtained cyclohexanone oxime may be further reacted by Beckmann rearrangement (Beckmann rearrangement) to form caprolactam. The beckmann rearrangement can be carried out in the liquid phase and the gas phase. The caprolactam formed can be used as starting material for the production of polyamide-6.
According to another preferred embodiment of the process of the invention, the ketone is cyclododecanone and the oxime formed is cyclododecanone oxime. Subsequently, the obtained cyclododecanone oxime may be further reacted by beckmann rearrangement to form laurolactam. The laurolactam formed can be used as starting material for the production of polyamide-12.
A chemical plant is any apparatus that manufactures or otherwise processes a desired chemical substance. This includes units for one or more chemical or physical operations such as heating, cooling, mixing, distillation, extraction and reaction. It usually further comprises all auxiliary equipment such as a reflux unit, a coolant supply, a pump, a heat exchanger and piping. The exact configuration of a chemical plant depends inter alia on the starting material substances and the type and purity of the desired end product, but also on the scale and type of the process carried out. In the case of processes carried out which produce waste water, the chemical plant also comprises all the plant components necessary to convert the waste water into effluent which can be discharged, for example, into the sea, rivers or ditches.
As used herein, a "continuous method" is a method that operates 24 hours per day, seven days per week, except for infrequent interruptions due to, for example, process disturbances, maintenance activities, or for economic reasons. In other words, a continuous process for producing an oxime as used herein is a process wherein an aldehyde or ketone is charged without interrupting the process and wherein an oxime is withdrawn without interrupting the process. The continuous process for producing an oxime may be carried out at a constant rate or its rate may fluctuate with the passage of time.
The chemical plant in which the process of the invention is carried out is preferably of industrial scale. As used herein, industrial scale means an oxime production rate of at least 1000kg of oxime per hour, more preferably at least 2000kg of oxime per hour, even more preferably at least 4000kg of oxime per hour, most preferably at least 6000kg of oxime per hour.
As used herein, converting an aldehyde or ketone by a chemical reaction means that the aldehyde or ketone is partially or fully converted to form an oxime as a product. Preferably, at least 50 mole%, more preferably at least 80 mole%, more preferably at least 96 mole% and most preferably at least 99 mole% of the aldehyde or ketone is converted to the oxime.
In another embodiment of the present invention, there is provided a chemical plant suitable for producing an oxime, the chemical plant comprising:
a. a chemical reaction zone for forming an oxime;
b. an oxime purification and recovery zone for purifying and recovering the oxime formed;
c. a zone for forming an aqueous phase containing phosphate radicals; and
d. a dephosphorizing zone in which solid magnesium ammonium phosphate hexahydrate is formed and separated from the aqueous phase.
Generally, the oxime-forming chemical reaction zone may comprise:
-charging an aldehyde or a ketone;
charging (batch or continuous mode) a phosphorus-containing compound, such as for example an aqueous hydrogen peroxide solution containing a phosphorus compound or phosphoric acid;
optionally, charging a solvent, such as, for example, toluene or tert-butanol; and
contacting the aldehyde or ketone with the (in situ formed) hydroxylamine.
Generally, the oxime purification and recovery zone for purifying and recovering the oxime formed may comprise:
a washing unit, wherein the oxime-containing phase is washed with water and/or an aqueous solution (e.g. aqueous caustic); and
a distillation unit, wherein the oxime is separated from other components (e.g. solvent like toluene, unconverted aldehyde or ketone).
In general, the zone forming the aqueous phase containing phosphate can comprise:
a unit for separating an aqueous phase containing phosphorus compounds from the process liquid originating from the chemical reaction zone, such as for example a liquid-liquid separator or a stripper;
optionally a unit for separating the aqueous phase containing the phosphorus compound from the oxime-containing organic phase which has been washed with water and/or an aqueous solution (e.g. aqueous caustic), such as for example a liquid-liquid separator;
-optionally, a stripping unit, wherein volatile organic compounds are stripped from the aqueous phase (e.g. steam stripping); and
-optionally a unit for converting organophosphorus to phosphate;
in general, the dephosphorising zone, which forms solid magnesium ammonium phosphate hexahydrate and is separated from the aqueous phase, may comprise:
-optionally a unit for converting organophosphorus to phosphate;
-charging an optional pH-adjusting chemical, a source of magnesium ions and/or a source of ammonium ions;
magnesium ammonium phosphate hexahydrate separation unit (e.g. filter).
In one embodiment of the chemical plant of the present invention, the chemical plant further comprises:
e. a biochemical wastewater treatment area.
Generally, the biochemical wastewater treatment zone may comprise:
-a settling zone wherein solids are removed from the wastewater by gravity;
-a filtration zone in which a colloidal suspension of fine solids can be removed from the wastewater by filtration;
-an oxidation zone wherein the biochemical oxygen demand of the wastewater is reduced by biochemical oxidation and optionally by chemical oxidation; and
-a pH adjustment zone, wherein the pH of the oxidized wastewater is adjusted to reduce its chemical reactivity.
According to an embodiment of the chemical plant of the present invention, the chemical plant further comprises:
f. a fine filtering area for filtering the wastewater discharged from the biochemical wastewater treatment area.
The fine filtration zone that filters the wastewater discharged from the biochemical wastewater treatment zone may comprise filtration through a sand bed, wherein the major solid contaminants are removed.
In a preferred embodiment of the chemical plant of the invention, the filtration zone comprises a sand bed.
Preferably, in the chemical plant of the present invention, the ketone is cyclohexanone or cyclododecanone, and the resulting cyclohexanone oxime or cyclododecanone oxime is further reacted by beckmann rearrangement to form caprolactam or laurolactam, respectively.
Most preferably, in the chemical plant of the present invention, the oxime is cyclohexanone oxime.
Magnesium ammonium phosphate hexahydrate is a unique fertilizer in that it provides three essential nutrients for plants: magnesium, nitrogen and phosphorus. In addition to its unique composition, magnesium ammonium phosphate hexahydrate has a slow release profile. As used herein, the slow release profile means that struvite does not (or hardly) release its nutrients immediately, but rather over a period of time.
In another aspect of the invention, there is provided a fertilizer product comprising magnesium ammonium phosphate hexahydrate, obtainable by the process of the invention for the production of an oxime.
The process of the present invention for producing oximes is much more ecologically beneficial than processes known in the art. Thus, the products of such processes are also much more ecologically beneficial than products produced via other processes. This particular feature of such ecologically much more beneficial products can be guaranteed, for example, by certification (certification).
As used herein, cyclohexanone oxime that can be obtained by the process of the present invention is a product resulting from the conversion of cyclohexanone.
Preferably, the compound cyclohexanone oxime of the obtained cyclohexanone oxime is in an amount of at least 92 wt.%; more preferably at least 97 wt.%; even more preferably, at least 99 wt.%; also preferably, at least 99.5 wt.%; most preferably, at least 99.9 wt.%. Cyclohexanone, toluene and water may be present as impurities.
FIG. 1 schematically shows a conventional state of the art plant for the production of cyclohexanone oxime and for the treatment of waste water.
FIG. 2 shows a plant for the production of cyclohexanone oxime and for the treatment of waste water according to the invention.
FIG. 3 is a schematic illustration based on
A cyclohexanone oxime production zone of the art, which is the cyclohexanone oxime production zone [ A ] depicted in FIGS. 1 and 4]An example of (2).
FIG. 4 schematically shows a cyclohexanone oxime production zone based on the cyclohexanone ammoximation technique, which is one example of the cyclohexanone oxime production zone [ A ] depicted in FIGS. 1 and 4.
FIG. 1 schematically shows a conventional state of the art plant for the production of cyclohexanone oxime and for the treatment of waste water, comprising a cyclohexanone oxime production zone [ A ], a waste water treatment plant [ C ] and a filtration zone [ D ].
The cyclohexanone oxime-producing zone [ A ] comprises a reaction zone for forming cyclohexanone oxime and a cyclohexanone oxime-separating and purifying zone. Purified cyclohexanone oxime is discharged from the cyclohexanone oxime production zone [ A ] via line [1 ]. Phosphorus-containing waste water is discharged from the cyclohexanone oxime production zone [ A ] through a line [2 ].
In the wastewater treatment plant [ C ], organic compounds are largely removed from wastewater charged through the line [2 ]. Alternatively, wastewater from other plants is charged into the same wastewater treatment plant [ C ] (not shown). Preferably, the organic compounds are removed by biochemical oxidation. The sludge thus formed contains a portion of the phosphorus charged to the wastewater treatment plant [ C ], which is discharged through line [8 ]. The treated wastewater contains less organic compounds than the wastewater charged into the wastewater treatment plant [ C ], and is discharged through the line [9 ].
In the filtration zone [ D ], particulate solids are removed from the wastewater charged through line [9 ]. The filtration zone [ D ] may contain one or more sand bed filters and/or membrane filtration units. The solids removed in the filtration zone [ D ] are discharged through line [10 ]. The treated wastewater obtained from the filtration zone [ D ] is discharged through line [11] into, for example, the sea, river or ditch.
FIG. 2 shows a plant for the production of cyclohexanone oxime and for wastewater treatment according to the present invention, which comprises a cyclohexanone oxime production zone [ A ], a dephosphorization zone [ B ], a wastewater treatment plant [ C ] and a filtration zone [ D ].
The cyclohexanone oxime-producing zone [ A ] comprises a reaction zone for forming cyclohexanone oxime and a cyclohexanone oxime-separating and purifying zone. Purified cyclohexanone oxime is discharged from the cyclohexanone oxime production zone [ A ] via line [1 ]. Phosphorus-containing waste water is discharged from the cyclohexanone oxime production zone [ A ] through a line [2 ].
In the dephosphorizing zone [ B ], magnesium ammonium phosphate hexahydrate is formed and separated from the wastewater charged through the line [2 ]. Optionally, wastewater from other plants is fed to the same dephosphorizing zone [ B ] (not shown). Optionally, a chemical to adjust the pH is loaded through line [3 ]. Optionally, a source of magnesium ions is charged via line [4 ]. Alternatively, the ammonium ion source is charged via line [5 ]. The magnesium ammonium phosphate hexahydrate formed is discharged through line 6. Optionally, the magnesium ammonium phosphate hexahydrate formed is further treated, for example dried or blended with other compounds (not shown), before application as a fertilizer. The dephosphorizing wastewater is discharged from the dephosphorizing zone (B) through a pipeline (7). Alternatively, the waste water from the cyclohexanone oxime production zone [ A ] is treated to convert organic phosphorus to phosphate (not shown) before being charged into the dephosphorization zone [ B ].
In the wastewater treatment plant [ C ], organic compounds are largely removed from wastewater charged through the line [7 ]. Alternatively, wastewater from other plants is charged into the same wastewater treatment plant [ C ] (not shown). Preferably, the organic compounds are removed by biochemical oxidation. The sludge thus formed contains a portion of the phosphorus charged to the wastewater treatment plant [ C ], which is discharged through line [8 ]. The treated wastewater contains less organic compounds than the wastewater charged into the wastewater treatment plant [ C ], and is discharged through the line [9 ].
In the filtration zone [ D ], particulate solids are removed from the wastewater charged through line [9 ]. The filtration zone [ D ] may contain one or more sand bed filters and/or membrane filtration units. The solids removed in the filtration zone [ D ] are discharged through line [10 ]. The treated wastewater obtained from the filtration zone [ D ] is discharged through a pipeline [11] into, for example, the sea, a river or a ditch.
FIG. 3 is a schematic illustration based on
A cyclohexanone oxime production zone of the art, which is the cyclohexanone oxime production zone [ A ] depicted in FIGS. 1 and 2]An example of (a).
Through a pipeline [ a ]]Charged ammonia gas and the passing line [ b ]]The air charged into the ammonia combustion unit is combusted together, thereby forming NOxA gas. These NOsxThe gas is absorbed in the phosphate-containing aqueous solution, thereby forming nitrates. The nitrate-loaded aqueous phosphate solution is charged into a hydroxylamine formation zone in which nitrate is used via line [ c ]]The charged hydrogen is catalytically reduced to form hydroxylamine. The aqueous solution thus formed containing phosphate and hydroxylamine is passed through line d]The charged freshly added cyclohexanone and recycled cyclohexanone are contacted with the organic solution of the solvent toluene in a cyclohexanone oxime forming zone, thereby forming cyclohexanone oxime. The phosphate-containing aqueous solution having a low hydroxylamine content is discharged from the cyclohexanone oxime formation zone and passed via NOxThe absorption unit is recycled to the hydroxylamine formation zone.
The solution of cyclohexanone oxime in toluene containing a small amount of phosphate is removed from the cyclohexanone oxime formation zone and washed in the cyclohexanone oxime washing zone with washing water fed via line [ e ], whereby a phosphate-containing aqueous phase and a washed solution of cyclohexanone oxime in toluene are obtained. The aqueous phase containing phosphate is separated from the solution of cyclohexanone oxime in toluene and partly discharged as the first aqueous phase containing phosphate and partly recycled to the process. In the cyclohexanone oxime distillation zone, the washed solution of cyclohexanone oxime in toluene is distilled, whereby recycled toluene and cyclohexanone as well as cyclohexanone oxime discharged through line [1] are obtained.
In the cyclohexanone oxime production zone, NO is formed as a result of the combustion unitxHydroxylamine is formed in the hydroxylamine-forming zone (: reaction 2) and cyclohexanone oxime is formed in the cyclohexanone oxime-forming zone (: reaction 3), forming water. The water formed tends to accumulate in the phosphorusIn aqueous acid salt solution. Steam stripping is applied to the aqueous phosphate solution to balance the amount of water in the process, thereby obtaining a second aqueous phase containing phosphate.
The first aqueous phase containing phosphate and the second aqueous phase containing phosphate are treated in a stripping unit that removes volatile organic compounds. The stripped aqueous phase thus obtained is a phosphorus-containing waste water discharged from the cyclohexanone oxime production zone [ A ] via line [2 ].
FIG. 4 schematically shows a cyclohexanone oxime production zone based on the cyclohexanone ammoximation technique, which is one example of the cyclohexanone oxime production zone [ A ] depicted in FIGS. 1 and 2.
Ammonia gas or aqueous ammonia is charged through line [ f ], an aqueous hydrogen peroxide solution containing a phosphorus compound is charged through line [ g ], and cyclohexanone is charged into the cyclohexanone oxime-forming zone through line [ h ]. Generally, recycled or fresh ammoximation catalyst and recycled or fresh solvent tert-butanol are also charged into the cyclohexanone oxime forming zone. The reaction mixture obtained is subjected to distillation after removal of the catalyst, whereby inter alia the solvent tert-butanol and excess ammonia go to the top and an aqueous phase containing cyclohexanone oxime and phosphorus compounds is obtained as bottom stream.
The aqueous phase containing cyclohexanone oxime and phosphorus compounds is extracted with toluene, whereby a toluene organic phase containing cyclohexanone oxime and a first waste water stream containing phosphorus compounds and organic substances is obtained. The toluene organic phase containing cyclohexanone oxime is washed with an (optionally caustic) wash water charged via line [ i ], thereby obtaining a washed solution of cyclohexanone oxime in toluene and a second waste water stream containing phosphorus compounds and organic substances. The second waste water stream containing phosphorus compounds and organic substances is separated from the solution of cyclohexanone oxime in toluene and discharged. In the distillation unit, the washed solution of cyclohexanone oxime in toluene is distilled, whereby (optionally) recycled toluene and cyclohexanone as well as cyclohexanone oxime discharged via line [1] are obtained.
A first waste water stream containing phosphorus compounds and organic substances is combined with a second waste water stream containing phosphorus compounds and organic substances and discharged from the cyclohexanone oxime production zone [ A ] via line [2 ].
Cyclohexanol may also be charged through line [ h ] in place of cyclohexanone. In this case, cyclohexanol is first converted into cyclohexanone by the action of hydrogen peroxide, and the cyclohexanone is then converted into cyclohexanone oxime.
The invention is illustrated by the following examples, but is not intended to be limited thereto.
Comparative experiment A
Continuous process for the production of cyclohexanone oxime in a chemical plant
Process in which hydroxylamine is first formed by selective reduction of nitrate, the hydroxylamine formed is then reacted with cyclohexanone at about 70 ℃ to form cyclohexanone oxime, the cyclohexanone oxime formed is then separated from the reaction mixture and the waste water produced is thus treated in a biochemical waste water treatment plant comprising:
-NH3a combustion unit;
-NOxan absorption unit;
-a hydroxylamine-forming region;
-a cyclohexanone oxime forming zone;
-a cyclohexanone oxime wash zone;
-a cyclohexanone oxime distillation zone;
-a steam stripper for removing water from the aqueous phosphate solution;
-a stripping unit for removing organic compounds from a first aqueous phase containing phosphate and a second aqueous phase containing phosphate;
-a biochemical wastewater treatment plant with sludge removal;
-a filtration zone for removing solids located downstream of a biochemical wastewater treatment plant; and
-a discharge for discharging treated wastewater from the filtration zone;
as described above and substantially as depicted in fig. 1 and 3, for a period of time.
This commercial chemical plant outputs on average about 25t cyclohexanone oxime per hour, which equates to a plant output of about 200kta cyclohexanone oxime per year (assuming 8000 hours/year of efficient production). The main raw materials charged to the cyclohexanone oxime production zone of this chemical plant are ammonia, air, hydrogen and cyclohexanone. In addition, a small amount of phosphoric acid and toluene was charged to compensate for the loss, and the washing water was charged into the cyclohexanone oxime washing zone.
The waste water discharged from the cyclohexanone oxime production zone is mixed with waste water from other chemical plants at the caprolactam production site. These other chemical plants include a chemical plant for producing cyclohexanone by oxidation of cyclohexane, a chemical plant for producing caprolactam by liquid phase beckmann rearrangement of cyclohexanone oxime followed by neutralization with ammonia, a chemical plant for purifying caprolactam and a chemical plant for crystallization of ammonium sulfate.
The total amount of wastewater charged into the biochemical wastewater treatment plant was about 150m3H and contains on average about 120ppm phosphorus (in the form of phosphate). Treated wastewater discharged from a filtration zone for solids removal located downstream of a biochemical wastewater treatment plant contains on average about 110ppm phosphorus (in the form of phosphate).
In example 1 (according to the present invention), the cyclohexanone oxime production zone, the biochemical wastewater treatment plant with removal of sludge and the filtration zone for solids removal located downstream of the biochemical wastewater treatment plant were the same as the cyclohexanone oxime production zone, the biochemical wastewater treatment plant with removal of sludge and the filtration zone for solids removal located downstream of the biochemical wastewater treatment plant in comparative experiment a. In addition, the chemical plant in example 1 was provided with a dephosphorization zone.
Example 1
Continuous process for the production of cyclohexanone oxime in a chemical plant
Process in which hydroxylamine is first formed by selective reduction of nitrate, the hydroxylamine formed is then reacted with cyclohexanone at about 70 ℃ to form cyclohexanone oxime, the cyclohexanone oxime formed is then separated from the reaction mixture and the waste water produced thereby is treated in a dephosphorising zone and thus in a biochemical waste water treatment plant comprising:
-NH3a combustion unit;
-NOxan absorption unit;
-a hydroxylamine-forming region;
-a cyclohexanone oxime forming zone;
-a cyclohexanone oxime wash zone;
-a cyclohexanone oxime distillation zone;
-a steam stripper for removing water from the aqueous phosphate solution;
-a stripping unit for removing organic compounds from a first aqueous phase containing phosphate and a second aqueous phase containing phosphate;
-a dephosphorisation zone wherein magnesium ammonium phosphate hexahydrate is formed and discharged;
-a biochemical wastewater treatment plant with sludge removal;
-a filtration zone for removing solids located downstream of a biochemical wastewater treatment plant; and
-a discharge for discharging treated wastewater from the filtration zone;
as described above and substantially as depicted in fig. 2 and 3, for a period of time.
This commercial chemical plant outputs on average about 25t cyclohexanone oxime per hour, which equates to a plant output of about 200kta cyclohexanone oxime per year (assuming 8000 hours/year of efficient production). The main raw materials charged to the cyclohexanone oxime production zone of this chemical plant are ammonia, air, hydrogen and cyclohexanone. In addition, a small amount of phosphoric acid and toluene was charged to compensate for the loss, and the washing water was charged into the cyclohexanone oxime washing zone.
The waste water discharged from the cyclohexanone oxime production zone is mixed with waste water from other chemical plants at the caprolactam production site. These other chemical plants include a chemical plant for producing cyclohexanone by oxidation of cyclohexane, a chemical plant for producing caprolactam by liquid-phase beckmann rearrangement of cyclohexanone oxime followed by neutralization with ammonia, a chemical plant for purifying caprolactam and a chemical plant for crystallization of ammonium sulfate.
The total amount of wastewater charged to the dephosphorizing zone was about 150m3H and contains on average about 120ppm phosphorus (as phosphate)Forms). In the dephosphorizing zone, the pH is maintained at about 9 by the addition of caustic. In the dephosphorization zone, the purification liquid containing ammonium sulfate and MgCl from the ammonium sulfate crystallization plant are added2Maintaining the molar ratio of P to Mg to N at about 1:1.2: 2. The magnesium ammonium phosphate hexahydrate thus formed is separated from the waste water and discharged. The discharged magnesium ammonium phosphate hexahydrate is used as a fertilizer after being dried.
The wastewater discharged from the dephosphorising zone, which contains about 5ppm of phosphorus (in the form of phosphate), is fed to a biochemical wastewater treatment plant with sludge removal. The treated wastewater discharged from a filtration zone for solids removal located downstream of a biochemical wastewater treatment plant contains less than 0.5ppm phosphorus (in the form of phosphate).
Comparison of comparative experiment A with example 1 shows that
Technical process for the production of cyclohexanone the treated wastewater discharged from a filtration zone for solids removal located downstream of a biochemical wastewater treatment plant is reduced from about 110ppm phosphorus (in phosphate form) to less than 0.5ppm phosphorus (in phosphate form) due to the addition of a dephosphorisation zone wherein magnesium ammonium phosphate hexahydrate is formed and discharged. In addition, magnesium ammonium phosphate hexahydrate is obtained which can be used as a discharge for fertilizers.
Comparative experiment B
A continuous process for the production of cyclohexanone oxime is carried out in a chemical plant in which cyclohexanone, ammonia and hydrogen peroxide are reacted at about 85 ℃ in the presence of a TS-1 catalyst and tert-butanol as solvent, and the cyclohexanone oxime thus formed is separated from the reaction mixture by extraction in toluene, washed with an aqueous caustic solution and then separated by distillation, and the resulting wastewater is thus treated in a biochemical wastewater treatment plant, which comprises:
-a cyclohexanone oxime forming zone;
-a catalyst filtration zone for recovering the TS-1 catalyst;
-a distillation column in which the solvent tert-butanol and excess ammonia are passed to the top and an aqueous phase containing cyclohexanone oxime and phosphorus compounds is obtained as bottom stream;
-an extraction zone wherein a toluene organic phase comprising cyclohexanone oxime and a first waste water stream comprising phosphorus compounds and organics are obtained;
-a washing zone, wherein the toluene organic phase containing cyclohexanone oxime is washed with caustic washing water, thereby obtaining a washed solution of cyclohexanone oxime in toluene and a second waste water stream containing phosphorus compounds and organics;
-a cyclohexanone oxime distillation zone;
-a biochemical wastewater treatment plant with sludge removal;
-a filtration zone for removing solids located downstream of a biochemical wastewater treatment plant; and
-a discharge for discharging treated wastewater from the filtration zone;
this method is simulated as described above and substantially as depicted in fig. 1 and 4.
This chemical plant outputs on average about 12.5t cyclohexanone oxime per hour, which equals about 100kta cyclohexanone oxime per year of plant output (assuming 8000 hours/year of efficient production). The main raw materials charged to the cyclohexanone oxime production zone of this chemical plant were ammonia, 27 wt.% aqueous hydrogen peroxide solution and cyclohexanone. The 27 wt.% aqueous hydrogen peroxide solution used was produced in a hydrogen peroxide plant based on the well-known anthraquinone technology. The phosphorus content of the 27 wt.% aqueous hydrogen peroxide solution was 27 wt.% H per ton2O2About 0.5kg of trioctyl phosphate in water and 27 wt.% H per ton2O2The aqueous solution was about 1kg phosphoric acid. In addition, small amounts of tert-butanol and toluene are charged to the cyclohexanone oxime production zone of this chemical plant to compensate for losses and caustic wash water is charged to the cyclohexanone oxime wash zone.
All the wastewaters (including the first wastewater stream containing phosphorus compounds and organic substances and the second wastewater stream containing phosphorus compounds and organic substances discharged from the cyclohexanone oxime production zone) are combined and fed to a biochemical wastewater treatment plant with sludge removal. The treated wastewater discharged from a filtration zone for solids removal located downstream of a biochemical wastewater treatment plant contains on average about 150ppm phosphorus (partly in the form of phosphate and partly in the form of organophosphorus).
In example 2 (according to the present invention), the cyclohexanone oxime production zone, the biochemical wastewater treatment plant with removal of sludge and the filtration zone for solids removal located downstream of the biochemical wastewater treatment plant were the same as the cyclohexanone oxime production zone, the biochemical wastewater treatment plant with removal of sludge and the filtration zone for solids removal located downstream of the biochemical wastewater treatment plant in comparative experiment B. In addition, the chemical plant in example 2 was provided with a dephosphorization zone.
Example 2
A continuous process for the production of cyclohexanone oxime is carried out in a chemical plant in which cyclohexanone, ammonia and hydrogen peroxide are reacted at about 85 ℃ in the presence of a TS-1 catalyst and tert-butanol as solvent, and the cyclohexanone oxime thus formed is separated from the reaction mixture by extraction in toluene, washed with an aqueous caustic solution and then separated by distillation, and the resulting wastewater is thus treated in a biochemical wastewater treatment plant, which comprises:
-a cyclohexanone oxime forming zone;
-a catalyst filtration zone for recovering the TS-1 catalyst;
-a distillation column in which the solvent tert-butanol and excess ammonia are passed to the top and an aqueous phase containing cyclohexanone oxime and phosphorus compounds is obtained as bottom stream;
-an extraction zone wherein a toluene organic phase comprising cyclohexanone oxime and a first waste water stream comprising phosphorus compounds and organics are obtained;
-a washing zone, wherein the toluene organic phase containing cyclohexanone oxime is washed with caustic washing water, thereby obtaining a washed solution of cyclohexanone oxime in toluene and a second waste water stream containing phosphorus compounds and organics;
-a cyclohexanone oxime distillation zone;
-an organophosphorus conversion unit;
-a dephosphorisation zone wherein magnesium ammonium phosphate hexahydrate is formed and discharged;
-a biochemical wastewater treatment plant with sludge removal;
-a filtration zone for removing solids located downstream of a biochemical wastewater treatment plant; and
-a discharge for discharging treated wastewater from the filtration zone;
this method is simulated as described above and substantially as depicted in fig. 2 and 4.
This chemical plant outputs on average about 12.5t cyclohexanone oxime per hour, which equals about 100kta cyclohexanone oxime per year of plant output (assuming 8000 hours/year of efficient production). The main raw materials charged to the cyclohexanone oxime production zone of this chemical plant were ammonia, 27 wt.% aqueous hydrogen peroxide solution and cyclohexanone. The 27 wt.% aqueous hydrogen peroxide solution used was produced in a hydrogen peroxide plant based on the well-known anthraquinone technology. The phosphorus content of the 27 wt.% aqueous hydrogen peroxide solution was 27 wt.% H per ton2O2About 0.5kg of trioctyl phosphate in water and 27 wt.% H per ton2O2The aqueous solution was about 1kg phosphoric acid. In addition, small amounts of tert-butanol and toluene are charged to the cyclohexanone oxime production zone of this chemical plant to compensate for losses and caustic wash water is charged to the cyclohexanone oxime wash zone.
All the waste waters, including the first waste water stream comprising phosphorus compounds and organic matter and the second waste water stream comprising phosphorus compounds and organic matter discharged from the cyclohexanone oxime production zone, are combined and fed to the organophosphorus conversion unit. In this organophosphorus conversion unit, an organophosphorus compound such as, for example, trioctyl phosphate is almost completely hydrolyzed under alkaline conditions. The pH, temperature and residence time in this unit were maintained at about 11, 50 ℃ and 8 hours, respectively. The pH was adjusted by the administration of NaOH.
The treated wastewater discharged from the organophosphorus conversion unit is fed to a dephosphorizing zone. In the dephosphorizing zone, the pH is maintained at about 9. In the dephosphorization zone, the purification liquid containing ammonium sulfate and MgCl from the ammonium sulfate crystallization plant are added2Maintaining the molar ratio of P to Mg to N at about 1:1.2: 2. The magnesium ammonium phosphate hexahydrate thus formed is separated from the waste water and discharged. The discharged magnesium ammonium phosphate hexahydrate is used as a fertilizer after being dried.
Wastewater discharged from the dephosphorization zone is charged into a biochemical wastewater treatment plant having sludge removed. The treated wastewater discharged from a filtration zone for solids removal located downstream of a biochemical wastewater treatment plant contains less than 0.5ppm phosphorus (in the form of phosphate).
Comparison of comparative experiment B with example 2 shows that for a process for the production of cyclohexanone based on ammoximation, the treated wastewater discharged from a filtration zone for solids removal located downstream of a biochemical wastewater treatment plant is reduced from about 110ppm phosphorus (in phosphate form) to less than 0.5ppm phosphorus (in phosphate form) due to the addition of an organophosphorus conversion unit and a dephosphorisation zone in which magnesium ammonium phosphate hexahydrate is formed and discharged. In addition, magnesium ammonium phosphate hexahydrate is obtained which can be used as a discharge for fertilizers.
Claims (13)
1. A method for producing an oxime in an industrial-scale plant, the method comprising:
a. converting an aldehyde or ketone into an oxime by a chemical reaction at a temperature of 15 ℃ to 115 ℃ to obtain a reaction mixture comprising the oxime formed;
b. recovering the formed oxime from the reaction mixture;
c. producing a first aqueous phase containing phosphate ions;
d. reducing the level of phosphate ions in the first aqueous phase, thereby forming a second aqueous phase; and
e. (ii) discharging the second aqueous phase,
wherein the reduction of the content of phosphate ions in the first aqueous phase is achieved by:
1) forming a salt with a molar ratio of N to Mg to P of 1:1: 1; and
2) separating the salt with a molar ratio of N: Mg: P of 1:1:1 from the second aqueous phase.
2. The method of claim 1, wherein the method further comprises:
f. reducing the phosphate ion content of the second aqueous phase, thereby forming a third aqueous phase; and
g. (iii) discharging the third aqueous phase,
wherein the reduction of the content of phosphate ions in the second aqueous phase is achieved by:
1) charging the second aqueous phase into a biochemical wastewater treatment plant, and
2) discharging the third aqueous phase from the biochemical wastewater treatment plant.
3. The process according to claim 1, wherein the salt having a molar ratio of N: Mg: P of 1:1:1 is magnesium ammonium phosphate hexahydrate.
4. The process according to claim 2, wherein the salt having a molar ratio of N: Mg: P of 1:1:1 is magnesium ammonium phosphate hexahydrate.
5. The process according to any one of claims 1 to 4, wherein the salt formation is achieved by adding an incinerator effluent stream to the first aqueous phase.
6. Process according to any one of claims 1 to 4, wherein the salt formation is achieved by adding a stream originating from an ammonium sulphate crystallization plant and comprising ammonium ions and at least one inorganic or organic impurity originating from a caprolactam production process to the first aqueous phase.
7.A process according to any one of claims 1 to 4, wherein in the chemical reaction an aldehyde or ketone is converted to an oxime with hydroxylamine.
8. The method according to any one of claims 1 to 4, wherein the method for producing an oxime is: an ammoximation process wherein in step a. an aldehyde or ketone, ammonia and hydrogen peroxide are reacted in the presence of a catalyst; or a process wherein hydroxylamine is first formed by selective reduction of nitrate followed by reaction of the formed hydroxylamine with cyclohexanone to form an oxime in step a.
9. The process according to any one of claims 1 to 4, wherein the ketone is selected from butanone, cyclohexanone or cyclododecanone.
10. The process according to any one of claims 1 to 4, wherein the oxime formed is selected from butanone oxime, cyclohexanone oxime or cyclododecanone oxime.
11. The process according to any one of claims 1 to 4, wherein the ketone is cyclohexanone and the oxime formed is cyclohexanone oxime.
12. An industrial chemical plant suitable for producing an oxime, wherein said chemical plant comprises:
a. a chemical reaction zone to form the oxime;
b. an oxime purification and recovery zone for purifying and recovering the oxime formed;
c. a zone for forming an aqueous phase containing phosphate radicals;
d. a dephosphorizing zone configured to form a salt having a molar ratio of N: Mg: P of 1:1:1 and separate said salt from said aqueous phase, wherein said dephosphorizing zone comprises a filter or centrifuge as a magnesium ammonium phosphate hexahydrate separation unit, wherein said salt having a molar ratio of N: Mg: P of 1:1:1 is magnesium ammonium phosphate hexahydrate.
13. The industrial chemical plant of claim 12, wherein an aldehyde or ketone is converted to an oxime in the chemical reaction zone, the ketone is cyclohexanone or cyclododecanone and the resulting oxime is cyclohexanone oxime or cyclododecanone oxime.
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Patent Citations (8)
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| CN1223970A (en) * | 1998-01-22 | 1999-07-28 | 中国石油化工总公司 | Method for treatment of waste water of ammonium sulfate |
| CN1547571A (en) * | 2001-05-31 | 2004-11-17 | Dsmip�Ʋ�����˾ | Disposal method of liquid containing phosphate, cyclohexanone and cyclohexanone oxime |
| DE102008050349A1 (en) * | 2007-10-02 | 2009-05-07 | Remondis Aqua Gmbh & Co. Kg | Precipitation of phosphorus from waste water to form magnesium ammonium phosphate, in waste water treatment plant, comprises displacing the waste water with magnesium chloride in crystallization stage, and displacing to stripping stage |
| EP2431336A1 (en) * | 2010-09-20 | 2012-03-21 | Akwadok BVBA | Method for purifying wastewater with ammonium removal |
| JP2013119523A (en) * | 2011-12-06 | 2013-06-17 | Sumitomo Chemical Co Ltd | Method for producing cyclohexanone oxime, and method and system of effluent treatment |
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| WO2014102106A1 (en) * | 2012-12-28 | 2014-07-03 | Dsm Ip Assets B.V. | Steam stripping inorganic process liquid discharged from hpo® extraction section and utilizing heat of condensation |
| CN108002661A (en) * | 2017-12-29 | 2018-05-08 | 什邡市长丰化工有限公司 | A kind of nitrogenous, phosphorus waste water processing method |
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| Publication number | Publication date |
|---|---|
| CN112912168A (en) | 2021-06-04 |
| TW202031637A (en) | 2020-09-01 |
| TWI822880B (en) | 2023-11-21 |
| WO2020078884A1 (en) | 2020-04-23 |
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