CN115960133A - Comprehensive recycling method for alkyl dichlorophosphine production byproducts - Google Patents
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Abstract
The invention discloses a comprehensive recycling method of alkyl dichlorophosphine production byproducts, which comprises the following steps: reacting olefinic acid compounds with alkyl dichlorophosphine in byproducts to generate a phosphorus-containing flame retardant or an intermediate thereof to obtain a reacted mixture, then gradually separating sodium chloride and a precipitate in the form of aluminum trichloride hydrate by increasing the content of hydrogen chloride in the system step by step in a graded manner to obtain a mixture containing the phosphorus-containing flame retardant or the intermediate thereof, a small amount of aluminum chloride, sodium chloride and hydrochloric acid, distilling and concentrating, adding sodium hydroxide, filtering, acidifying and concentrating the filtrate, extracting, and purifying; the method of the invention obtains pure sodium chloride, pure aluminum chlorohydrate and phosphorus-containing flame retardant or intermediate thereof, has clear and definite steps and functions, is simple and easy to control, and completely solves the problem of comprehensive utilization of the composite salt in the production process of the methyldichlorophosphine.
Description
Technical Field
The invention relates to the technical field of recycling of phosphorus-containing byproducts in the production process of alkyl dichlorophosphine serving as an organic phosphine intermediate, in particular to a comprehensive utilization method of a phosphorus-containing composite salt.
Background
Alkyl dichlorophosphine, also known as alkyl dichlorophosphine, is an important intermediate of an organic phosphine compound, particularly methyl dichlorophosphine, and is a core raw material for synthesizing a herbicide glufosinate-ammonium intermediate diethyl methylphosphonite. Currently, the mainstream production methods of methyldichlorophosphine mainly comprise the following three methods:
1. phosphorus trichloride and methane pass through a tubular reactor, a condenser and a fractionating device in the presence of a high-temperature high-pressure catalyst to obtain methyldichlorophosphine, deposits are easily generated in the method, the tubular reactor and the condenser are blocked, production interruption is caused, the product conversion rate is low, and the energy consumption is high.
2. Phosphorus trichloride, aluminum trichloride and chloromethane are subjected to complex reaction in a pressure kettle to generate a ternary complex, the ternary complex is reduced by aluminum powder to obtain a complex of methyldichlorophosphine and aluminum trichloride, the complex is dissociated into the methyldichlorophosphine under the action of sodium chloride, and a byproduct of composite salt of sodium chloride and aluminum chloride is remained.
3. Methyl chloride reacts with aluminum alloy to generate a mixture of methyl aluminum dichloride and dimethyl aluminum chloride, the mixture reacts with phosphorus trichloride to generate a complex of methyl dichlorophosphine and aluminum chloride, the complex reacts with sodium chloride to dissociate the methyl dichlorophosphine, and a byproduct, namely a composite salt of the sodium chloride and the aluminum chloride, is remained.
In the above methods, methods 2 and 3 do not have high temperature and high pressure, but because the dissociation of sodium chloride to methyldichlorophosphine and aluminum trichloride is insufficient, the content of the residual methyldichlorophosphine in the aluminum chloride and sodium chloride composite salt is higher, so that the aluminum chloride and sodium chloride composite salt cannot be well recycled, and the method is a great obstacle to the production of methyldichlorophosphine. To address this problem, the prior art proposes a number of different solutions, for example:
the Chinese patent CN105217667B mentions that the sodium chloride and the aluminum chloride are decomplexed by a mixture of decomplexer alcohol and ether to obtain the aluminum chloride for reuse, and the method does not mention the treatment of the phosphorus-containing compound and the sodium chloride in the sodium chloride and the compound salt sodium tetrachloroaluminate, and the phosphorus-containing compound and the sodium chloride cannot be recovered.
Chinese patent application CN108238621A mentions that after being dissolved, the compound salt is added with ferric chloride, hydrochloric acid, sodium hydroxide, sodium metaaluminate and the like for polymerization reaction, and then the solution is cooled and filtered to obtain polyaluminium chloride solution.
Chinese patent No. CN111187297A discloses a recovery processing method of phosphine-containing industrial by-products, which is to put the by-products generated in the production process of diethyl methylphosphite into a reaction vessel, add phenolic compounds or binary and above aromatic amine compounds or compounds containing oxirane functional groups, heat and react under the condition of isolating air, cool to room temperature, slowly dissolve the obtained solid in water, because the process of dissolving water is a heat release process, the adding speed needs to be controlled, and the stirring is uniform; cooling and filtering, wherein the obtained filter residue is used as a phosphorus flame retardant, the obtained first filtrate is continuously subjected to solid-liquid separation, specifically, the first filtrate is heated to 100-120 ℃ until crystals appear and the amount of the crystals does not increase any more, the heating is stopped, the first filtrate is filtered while the first filtrate is hot, and the obtained solid is sodium chloride crystals; and (3) slowly adding water into the obtained second filtrate, cooling to room temperature, adjusting the pH value of the second filtrate to prepare the polyaluminum chloride, specifically, adding ferric chloride and hydrochloric acid into the second filtrate, stirring and mixing uniformly, controlling the temperature of a reaction solution to be more than 85 ℃, then sequentially adding aluminum hydroxide and calcium metaaluminate, and controlling the reaction temperature to be 100 ℃ to react to obtain the polyaluminum chloride. Although the method can recycle the methyldichlorophosphine, the added phenolic substances, or binary and above aromatic amine compounds or epoxy compounds enter a polyaluminium system to cause polyaluminium pollution, so that the method has no application value, and in addition, the phenolic substances are dissolved in the filtrate in a large amount to bring a new waste liquid treatment problem. Moreover, the method has the disadvantages of complex process, high control difficulty and inconvenient operation.
Chinese patent No. CN111689508A discloses a method for treating tetrachloro sodium aluminate solid slag, which comprises (1) mixing tetrachloro sodium aluminate solid slag with water for dissociation, adding a separating agent to separate out aluminum chloride hexahydrate, or directly mixing tetrachloro sodium aluminate solid slag with the separating agent for dissociation, separating out aluminum chloride hexahydrate, and then carrying out primary solid-liquid separation to obtain aluminum chloride hexahydrate solid and primary filtrate; (2) And (3) concentrating and crystallizing the primary filtrate obtained in the step (1), and performing secondary solid-liquid separation to obtain sodium chloride solid and secondary filtrate, and returning the secondary filtrate to the step (1) to provide a separating agent required by precipitation of aluminum chloride hexahydrate. The process has proved to be capable of separating sodium chloride and aluminium chloride, however, the solution reported in this patent has errors, in particular, in step (1) it is not aluminium chloride hexahydrate but sodium chloride which is obtained first, and the sodium chloride and aluminium chloride which are finally obtained are not up to standard because of contamination from phosphorus-containing compounds in the solid residual mother liquor.
In conclusion, in the prior art, the utilization of the composite salt generated in the production process of the methyl dichlorophosphine cannot be fully and effectively realized, and some utilization methods have the problems of complex process, high control difficulty and the like.
Disclosure of Invention
In order to solve the technical problem of the comprehensive utilization of byproducts in the production of methyldichlorophosphine, the invention provides a comprehensive utilization method of the byproducts in the production process of the methyldichlorophosphine, and the method can fully and effectively recycle the byproducts in the production of the methyldichlorophosphine and has simple process and easy control.
In order to solve the problems, the invention adopts the following technical scheme:
a method for the integrated recovery and utilization of alkyl dichlorophosphine production byproducts, wherein the alkyl dichlorophosphine production byproducts comprise sodium chloride and aluminum chloride composite salts and alkyl dichlorophosphine, and the method comprises the following steps:
s1, reacting alkyl dichlorophosphine in the alkyl dichlorophosphine production byproduct with an olefinic acid compound in the presence of water to generate a phosphorus-containing flame retardant or an intermediate thereof, so as to obtain a first mixture containing the phosphorus-containing flame retardant or the intermediate thereof, sodium chloride and aluminum chloride;
s2, introducing hydrogen chloride and/or adding hydrochloric acid into the first mixture to enable the mass percentage of the hydrogen chloride in the mixture solution to reach 5% -15%, crystallizing and separating out sodium chloride, filtering, and washing a filter cake with hydrochloric acid to obtain pure sodium chloride solid, wherein the filtrate is a second mixture containing a very small amount of sodium chloride, aluminum trichloride, a phosphorus-containing flame retardant or an intermediate thereof and hydrochloric acid;
s3, introducing hydrogen chloride gas and/or adding hydrochloric acid into the filtrate obtained after filtration in the step S2 to enable the mass content of the hydrogen chloride in the mixture solution to be more than or equal to 35%, separating out aluminum chloride in the form of aluminum trichloride hydrate, filtering, washing a filter cake with hydrochloric acid, and drying to obtain the aluminum trichloride hydrate, wherein the filtrate is a third mixture containing a phosphorus-containing flame retardant or an intermediate thereof, aluminum chloride, sodium chloride and hydrochloric acid;
s4, distilling and concentrating the third mixture obtained in the step S3 to obtain concentrated hydrochloric acid and a phosphorus-containing flame retardant mixed with aluminum chloride and sodium chloride or an intermediate thereof;
and S5, separating and removing aluminum chloride and sodium chloride from the phosphorus-containing flame retardant mixed with the aluminum chloride and the sodium chloride or the intermediate thereof to obtain the phosphorus-containing flame retardant or the intermediate thereof.
Further, in the step S1, the alkyl dichlorophosphine production byproduct, the olefine acid compound and the dilute hydrochloric acid are mixed and reacted at the temperature of 40-100 ℃, wherein the mass percentage of the dilute hydrochloric acid is less than or equal to 10%.
According to a preferred aspect of the present invention, in step S1, the alkyl dichlorophosphine production byproduct is added to the diluted hydrochloric acid in batches, the system temperature is kept at 40-100 ℃ during the addition process, and when the addition of the alkyl dichlorophosphine production byproduct is finished, the olefinic acid compound or the aqueous solution in which the olefinic acid compound is dispersed is added, and the mixture is stirred and reacted to obtain the first mixture.
Further, in the steps S2 and S3, the hydrochloric acid for washing is concentrated hydrochloric acid with a mass percentage of 30% to 37%, respectively.
Further, in step S1, the olefinic acid compound is a 2-olefinic acid compound, more preferably a C4-C20 olefinic acid compound, and still more preferably a C4-C12 olefinic acid compound.
According to a given aspect of the invention, the olefinic acid compound has a structure represented by the following general formula (1):
wherein R is 1 、R 2 、R 3 Independently hydrogen, C1-C12 branched or straight chain alkyl, C3-C12 cycloalkyl with a C1-C12 alkyl side chain, phenyl which is unsubstituted or substituted with one or more C1-C12 branched or straight chain alkyl groups.
Further, in the general formula (1), R 1 、R 2 、R 3 Can independently be hydrogen, methyl, ethyl, propyl, cyclopropyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, methylphenyl or ethylphenyl, wherein R is 1 、R 2 、R 3 At most only one of which is a cyclic substituent.
In step S1, typical olefinic compounds include, but are not limited to, acrylic acid and/or methacrylic acid.
According to some preferred aspects of the present invention, before step S1, the content of the alkyl dichlorophosphine in the phosphorus-containing composite salt is obtained, and in step S1, the content of the alkyl dichlorophosphine in the phosphorus-containing composite salt is calculated according to the feeding molar ratio of the alkyl dichlorophosphine to the olefinic acid compound of 1: 1.01-1.3, and feeding.
Further preferably, in step S1, the molar ratio of alkyl dichlorophosphine to olefinic acid compound is 1: 1.01-1.1, and feeding.
According to some preferred aspects of the present invention, in step S1, the diluted hydrochloric acid is used in an amount of 1 to 10 times as much as the phosphorus-containing complex salt. Further preferably, in step S1, the amount of the dilute hydrochloric acid is 1 to 5 times of the phosphorus-containing composite salt.
According to some preferred aspects of the present invention, in step S1, the diluted hydrochloric acid is 2% to 5% by mass; in the step S2, the mass percentage of the hydrochloric acid used for washing the filter cake is 30-37%.
According to some preferred aspects of the invention, in the step S2, the hydrogen chloride is introduced to make the mass percentage of the hydrogen chloride in the mixture solution reach 6-10%; and/or introducing hydrogen chloride in the step S3 to ensure that the mass content of the hydrogen chloride in the mixture solution is 35-45%.
According to some preferred aspects of the invention, the alkyl dichlorophosphine is methyldichlorophosphine and the phosphorus-containing complex salt is a by-product from the production of methyldichlorophosphine. The comprehensive recycling method of the alkyl dichlorophosphine production byproduct also comprises the following steps: and S6, applying the sodium chloride solid obtained in the step S2 to a production process of the methyl dichlorophosphine.
According to some preferred aspects of the present invention, the integrated recycling method of the alkyl dichlorophosphine production by-product further comprises: and S7, applying the aluminum chlorohydrate obtained in the step S3 to the casting and sewage treatment industries.
According to some preferred aspects of the present invention, the integrated recycling method of the alkyl dichlorophosphine production by-product further comprises: and S8, further separating the concentrated hydrochloric acid obtained in the step S4 into hydrogen chloride gas and dilute hydrochloric acid, and using the hydrogen chloride gas and the dilute hydrochloric acid in the step S1.
Further, in step S8, the method for separating concentrated hydrochloric acid is a calcium chloride method or a sulfuric acid method; wherein, the calcium chloride method is to continuously separate out hydrogen chloride by using a calcium chloride solution as a dehydrating agent and continuously distill the calcium chloride solution to obtain dilute hydrochloric acid; the concentrated calcium chloride solution is continuously used as a dehydrating agent to separate hydrogen chloride; the sulfuric acid method is characterized in that concentrated sulfuric acid is used as a dehydrating agent to continuously separate out hydrogen chloride, a sulfuric acid solution is continuously distilled to obtain dilute hydrochloric acid and concentrated sulfuric acid, and the concentrated sulfuric acid is used as the dehydrating agent to continuously separate the hydrogen chloride.
Preferably, in step S1, the system is maintained at 70 to 90 degrees celsius for 1 to 2 hours after the precipitation of sodium chloride crystals and before filtration. The subsequent filtering and separating operation of the sodium chloride can be easier through heat preservation.
According to a preferred aspect of the present invention, step S5 further comprises:
s50: adding sodium hydroxide to the phosphorus-containing flame retardant mixed with the aluminum chloride and the sodium chloride or the intermediate thereof obtained in the step S4 to allow the aluminum chloride in a dissolved state to generate sodium chloride and aluminum hydroxide to obtain a mixture containing aluminum hydroxide, sodium chloride, the phosphorus-containing flame retardant or the sodium salt of the intermediate thereof, and filtering to obtain a filtrate which is an aqueous solution of the phosphorus-containing flame retardant or the sodium salt of the intermediate thereof and the sodium chloride;
s51: and (2) adding hydrochloric acid into the filtrate obtained in the step (S50) for acidification so as to enable the phosphorus-containing flame retardant or the intermediate sodium salt thereof to be dissociated into the phosphorus-containing flame retardant or the intermediate sodium salt thereof, then concentrating until the mixture is anhydrous to obtain the phosphorus-containing flame retardant or the intermediate phosphorus-containing flame retardant and sodium chloride, adding an organic solvent, uniformly stirring, filtering, concentrating the filtrate, carrying out reduced pressure distillation or recrystallization to obtain the phosphorus-containing flame retardant or the intermediate phosphorus-containing flame retardant, washing the filter cake with the organic solvent, and drying to obtain sodium chloride.
According to some preferred aspects of the present invention, the integrated recycling method of the alkyl dichlorophosphine production by-product further comprises one or more of the following steps:
s9, dissolving the sodium chloride obtained in the step S5 by using water to obtain a sodium chloride aqueous solution, returning to the step S1, mixing the sodium chloride aqueous solution with dilute hydrochloric acid, and dissolving the compound salt;
s10, returning the filter cake filtered in the step S50, namely the aluminum hydroxide, to the step S2 for generating aluminum chloride;
and S11, further preparing the phosphorus-containing flame retardant intermediate obtained in the step S51 into a phosphorus-containing flame retardant.
The invention also provides a production method of alkyl dichlorophosphine, which comprises the following steps:
(1) To obtain alkyl dichlorophosphine and sodium chloride and aluminum chloride composite salt by-products containing the alkyl dichlorophosphine,
(2) The comprehensive recycling method of the alkyl dichlorophosphine production by-product is adopted to recycle and obtain sodium chloride, aluminum chlorohydrate, phosphorus-containing flame retardant or an intermediate thereof.
Further, the production method also comprises (3) using the sodium chloride recovered in the above (2) as a raw material in the step (1).
In one embodiment according to the present invention, the alkyl dichlorophosphines include methyldichlorophosphine, phenyldichlorophosphine, and the like.
In the invention, if the mass percent concentration is not specified, the mass percent contents of the hydrogen chloride and the sulfuric acid in the related dilute hydrochloric acid and concentrated sulfuric acid are all the conventional definition ranges in the prior art.
The technical scheme provided by the invention has the following beneficial effects:
the treatment method can prepare the residual alkyl dichlorophosphine in the composite salt into the phosphorus-containing flame retardant with higher added value or the intermediate thereof; sodium chloride with the content of 99.5 percent or more can be obtained and can be reused in the production process of the methyldichlorophosphine; and can obtain the hydrated aluminum chloride with the content of 97 percent or more, which completely accords with the standard of the superior product of the hydrated aluminum chloride; the hydrochloric acid used can be separated to obtain hydrogen chloride and dilute hydrochloric acid, and the hydrogen chloride and dilute hydrochloric acid can be reused for treating the composite salt. Compared with the prior art, the method can realize the high-efficiency recovery of all useful substances, has no waste liquid in the whole process, lower recovery cost, simple process and simple and convenient operation, and can really and completely solve the problem of comprehensive utilization of byproducts in the production of alkyl dichlorophosphine.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a hydrogen spectrum of the flame retardant prepared in example 1.
Detailed Description
The present invention will be described in further detail below by taking a method of comprehensively utilizing a by-product (phosphorus-containing complex salt) in the production process of methyldichlorophosphine as an example.
According to some embodiments of the present invention, a method for the integrated utilization of byproducts from a methyldichlorophosphine production process comprises the steps of:
s1, adding the alkyl dichlorophosphine production by-product into dilute hydrochloric acid in batches, keeping the temperature of a system at 40-100 ℃ in the adding process, adding an olefine acid compound or an aqueous solution in which the olefine acid compound is dispersed after the alkyl dichlorophosphine production by-product is added, and stirring for reaction to obtain a first mixture; in this step, the amount of the olefinic acid compound to be charged is preferably in excess relative to the amount of the phosphorus-containing component such as methyldichlorophosphine, and the molar ratio of the olefinic acid compound to the methyldichlorophosphine to be charged is preferably 1.01 to 1.3:1, more preferably 1.01 to 1.1:1, more preferably 1.03 to 1.05:1. preferably, the temperature of the reaction is 40 to 100 degrees centigrade, more preferably 40 to 70 degrees centigrade, and still more preferably 45 to 60 degrees centigrade. The concentration of the dilute hydrochloric acid used is preferably 10% or less, more preferably 5% or less, and the amount used is generally 1 to 10 times, preferably 1 to 5 times, that of the phosphorus-containing complex salt; furthermore, the dilute hydrochloric acid used can be produced by separation from the concentrated hydrochloric acid obtained in the subsequent step.
S2, supplementing a certain amount of hydrogen chloride into the first mixture by utilizing an ionic effect, fully reducing the solubility of sodium chloride by utilizing a mode of increasing chloride ions, crystallizing and separating out, preferably performing heat preservation (so that the sodium chloride is subjected to crystal form transformation to facilitate subsequent filtration), filtering, washing a filter cake by hydrochloric acid with a certain concentration to obtain a pure sodium chloride solid, drying and then using the pure sodium chloride solid for producing the methyldichlorophosphine, wherein the filtrate is a second mixture containing a very small amount of sodium chloride, aluminum trichloride, a phosphorus-containing flame retardant or an intermediate thereof and hydrochloric acid. Preferably, the hydrogen chloride is supplemented to a concentration of 6% to 10% in the mixture solution. The temperature for the heat preservation may be 70 to 90 degrees centigrade, the heat preservation time may be 1 to 2 hours, and the hydrochloric acid concentration for washing is preferably concentrated hydrochloric acid, specifically 30 to 37%.
And S3, continuously introducing hydrogen chloride gas into the second mixture obtained in the step S2, continuously increasing the content of chloride ions, enabling the content of the hydrogen chloride to be more than 35%, separating out aluminum chloride in the form of aluminum trichloride hydrate, filtering, washing a filter cake with concentrated hydrochloric acid, combining filter liquor, and drying the filter cake to obtain the aluminum trichloride hydrate. The filtrate is a third mixture comprising the phosphorus-containing flame retardant or its intermediate, a small amount of aluminum chloride and sodium chloride, hydrochloric acid. The introduced hydrogen chloride can be hydrogen chloride generated by separating concentrated hydrochloric acid obtained in the subsequent step. Preferably, introducing hydrogen chloride to ensure that the content of the hydrogen chloride is 35-45%;
and S4, distilling and concentrating the third mixture obtained in the step S3 to obtain concentrated hydrochloric acid and a phosphorus-containing flame retardant mixed with a small amount of aluminum chloride and sodium chloride or an intermediate thereof. Preferably, the distillation concentration is reduced pressure multi-effect distillation concentration;
s5, separating and obtaining the phosphorus-containing flame retardant or the intermediate thereof from the phosphorus-containing flame retardant or the intermediate thereof mixed with a small amount of aluminum chloride and sodium chloride, wherein the method specifically comprises the following steps:
s50: neutralizing the phosphorus-containing flame retardant mixed with a small amount of aluminum chloride and sodium chloride or the intermediate thereof obtained in the step S4 with sodium hydroxide (preparing the dissolved aluminum chloride into sodium chloride and aluminum hydroxide to effectively separate the phosphorus-containing flame retardant and inorganic salt substances) to obtain a mixture of the aluminum hydroxide, the sodium chloride, the phosphorus-containing flame retardant or the intermediate sodium salt thereof, and filtering to obtain a filtrate which is an aqueous solution of the phosphorus-containing flame retardant or the intermediate sodium salt thereof and the sodium chloride;
s51: adding hydrochloric acid into the filtrate obtained in the previous step for acidification (hydrochloric acid is used for dissociating sodium salt of the phosphorus-containing flame retardant into the phosphorus-containing flame retardant or an intermediate thereof so as to facilitate solvent extraction), then concentrating until no water exists to obtain the phosphorus-containing flame retardant or the phosphorus-containing flame retardant intermediate and sodium chloride, adding an organic solvent, uniformly stirring, filtering, concentrating the filtrate, carrying out reduced pressure distillation (mainly suitable for liquid low-boiling-point flame retardants) or selecting a proper solvent for recrystallization (mainly suitable for solid flame retardants) to obtain the phosphorus-containing flame retardant, washing the filter cake with the organic solvent, and drying to obtain the sodium chloride. The organic solvent is not limited to a certain organic solvent or a mixture of several organic solvents, and can be properly selected according to different phosphorus-containing flame retardants.
Pure sodium chloride, pure aluminum chloride hydrate and phosphorus-containing flame retardant or an intermediate thereof are obtained through the steps, the steps are clear, the function is clear, and the sodium chloride can be used for producing the methyldichlorophosphine; the aluminum chlorohydrate has high purity, reaches the standard of high-grade aluminum chlorohydrate, and can be used in casting and sewage treatment industries. The method of the invention completely solves the problem of comprehensive utilization of the composite salt in the production process of the methyldichlorophosphine, solves the industrial problem and lays a foundation for large-scale industrialization of the methyldichlorophosphine.
The comprehensive utilization method of the present invention preferably further comprises one or more of the following steps:
and S6, applying the sodium chloride solid obtained in the step S2 to a production process of the methyl dichlorophosphine.
And S7, applying the aluminum chlorohydrate obtained in the step S3 to the casting and sewage treatment industries.
S8, further separating the concentrated hydrochloric acid obtained in the step S4 into hydrogen chloride gas and dilute hydrochloric acid, and using the hydrogen chloride gas and the dilute hydrochloric acid in the step S1, wherein the method for separating the concentrated hydrochloric acid can be a calcium chloride method or a sulfuric acid method, specifically, the calcium chloride method is a calcium chloride solution used as a dehydrating agent, continuously separating out hydrogen chloride, and continuously distilling the calcium chloride solution to obtain dilute hydrochloric acid; the concentrated calcium chloride solution is continuously used as a dehydrating agent to separate hydrogen chloride; the sulfuric acid method is characterized in that concentrated sulfuric acid is used as a dehydrating agent to continuously separate hydrogen chloride, and a sulfuric acid solution is continuously distilled to obtain dilute hydrochloric acid and concentrated sulfuric acid, and the concentrated sulfuric acid is used as the dehydrating agent to continuously separate the hydrogen chloride.
S9, dissolving the sodium chloride obtained in the step S51 by using water to obtain a sodium chloride aqueous solution, and returning to the step S1;
and S10, returning the filter cake obtained in the step S50, namely the aluminum hydroxide to the step S2 for generating aluminum chloride.
And S11, further preparing the phosphorus-containing flame retardant intermediate obtained in the step S51 into a phosphorus-containing flame retardant.
According to a preferred aspect of the invention, the olefinic acid compound of step S1 of the invention is one of the following:
wherein R is 1 、R 2 、R 3 Independently hydrogen, C1-C12 branched or straight chain alkyl, C3-C12 cycloalkyl with a C1-C12 alkyl side chain, phenyl which is unsubstituted or substituted with one or more C1-C12 branched or straight chain alkyl groups.
Further, in the general formula (1), R 1 、R 2 、R 3 Can be independently hydrogen, methyl, ethyl, propyl, cyclopropyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, methylphenyl or ethylphenyl, wherein R 1 、R 2 、R 3 Of which at most only one is a cyclic substituent.
In step S1, typical olefinic compounds include, but are not limited to, acrylic acid and/or methacrylic acid.
The equation for the reaction of olefinic acid compounds with methyldichlorophosphine to produce phosphorus-containing flame retardants or intermediates thereof is as follows:
the inventor innovatively discovers the comprehensive utilization method of the byproducts through a large number of experimental verifications and experimental optimization and simplification operations. The invention is not only suitable for the composite salt generated in the production process of methyldichlorophosphine, but also suitable for the composite salt generated in the production process of phenyl dichlorophosphine with similar friedel-crafts reaction.
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.
It should be noted that the terms "comprises" and "comprising," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a composition, process, method, apparatus, product, or apparatus that comprises a list of elements, steps, or units is not necessarily limited to the explicitly listed elements, but may include other elements, steps, or units not expressly listed or inherent to such process, method, product, or apparatus.
In the following examples, the conditions used may be further adjusted according to specific requirements, and the conditions not shown are generally conditions used in routine experiments. The raw materials used in the examples are all industrial products unless otherwise specified. The percentage% of the grade means mass% when not particularly stated.
In the following examples, the phosphorus-containing complex salt is a by-product from the production of methyldichlorophosphine, and includes a complex of sodium chloride and aluminum chloride, methyldichlorophosphine, and the like.
The components and phosphorus content of the phosphorus-containing composite salt are detected as follows: weighing 1.05 g of the compound salt sample, dissolving in 50 ml of water, fixing the volume in a 100 ml volumetric flask, measuring 1 ml of the volumetric flask, fixing the volume in a 1 l volumetric flask with water, measuring the phosphorus content by an ammonium molybdate spectrophotometry to be 0.205 mg/l, and converting the phosphorus content of the compound salt sample to be 19.5 g/kg. The reduced phosphorus content was 0.629 mol/kg. The sodium ion content was 12.23% as determined by ion chromatography, the reduced sodium chloride content was 31.11%, and the aluminum chloride content was 61.53% as determined by titration.
Example 1
The embodiment provides a recycling method of phosphorus-containing composite salt, which comprises the following steps:
s1, weighing 1000 g of compound salt in the same batch as a detection sample, adding the compound salt into 2100 g of 4.3% hydrochloric acid solution in batches, keeping the temperature of a system at about 50 ℃ in the adding process, adding 50 g of acrylic acid after the compound salt is completely added, and continuously stirring for 30 minutes to obtain a first mixture, wherein the reaction equation is as follows:
s2, introducing 105 g of hydrogen chloride into the first mixture obtained in the step S1, continuously stirring for 30 minutes to separate out sodium chloride, heating to 80 ℃, preserving heat for 1 hour, filtering, pulping and washing a filter cake by 650 g of 20% hydrochloric acid, filtering and drying to obtain 299.5 g of sodium chloride, detecting the sodium ion by using an ion chromatography to calibrate the sodium chloride content to 99.63%, detecting the phosphorus content by using an ammonium molybdate spectrophotometry to be 16.3ppm, and obtaining the recovery rate of 96.2%;
s3, combining the filtrate filtered in the step S2, continuously introducing 720 g of hydrogen chloride, filtering, washing a filter cake with 1100 g of 36.6% hydrochloric acid, drying the filter cake, weighing 1105 g, detecting the content of aluminum chlorohydrate to be 98.2% by a complexation method, detecting the content of sodium ions to be 0.56% by an ion chromatography, detecting the content of phosphorus to be 21.4ppm by an ammonium molybdate spectrophotometry, and recovering the content of phosphorus to be 99.3%;
s4, combining the filtrate and the washing liquid obtained in the step S3, carrying out reduced pressure distillation, and absorbing vacuum tail gas by cooled distilled hydrochloric acid to obtain 3544 g of 37% hydrochloric acid;
s5, neutralizing 97.3 g of residual liquid after distillation in the step S4 with sodium hydroxide, filtering, adding concentrated hydrochloric acid into filtrate to acidify until the pH value is 1, carrying out reduced pressure distillation, evaporating to remove water, adding 150 g of acetone, refluxing and dissolving the residue, filtering while hot, washing the solid with 50 g of hot acetone to obtain a sodium chloride solid and a phosphorus-containing flame retardant acetone solution, cooling to 5 ℃, filtering, and drying in vacuum to obtain 88.2 g (Mp 98-100 ℃) of a solid flame retardant (compound I-1), wherein the recovery rate is 92.3%. The hydrogen spectrum of the flame retardant is shown in FIG. 1, and is consistent with that of the compound I-1, thereby proving that the compound I-1 is successfully synthesized.
Example 2
The embodiment provides a recycling method of phosphorus-containing composite salt, which comprises the following steps:
s1, weighing 1000 g of compound salt in the same batch as a detection sample, adding the compound salt into 2100 g of 5.1% hydrochloric acid solution in batches, keeping the temperature of the system at about 50 ℃ in the adding process, adding 60 g of methacrylic acid after the compound salt is completely added, and continuously stirring for 30 minutes to obtain a first mixture, wherein the reaction equation is as follows:
s2, introducing 105 g of hydrogen chloride into the first mixture obtained in the step S1, continuously stirring for 30 minutes to separate out sodium chloride, heating to 70 ℃, preserving heat for 1.5 hours, filtering, pulping and washing a filter cake with 650 g of 20% hydrochloric acid, filtering and drying to obtain 305.4 g of sodium chloride, detecting the sodium ion by using an ion chromatography to calibrate the sodium chloride content to 99.57%, detecting the phosphorus content to be 22.1ppm by using an ammonium molybdate spectrophotometry, and obtaining the recovery rate of 98.2%;
s3, combining the filtrates filtered in the step S2, continuously introducing 720 g of hydrogen chloride, washing filter cakes by using 1100 g of 37% hydrochloric acid after filtering, weighing 1095 g of the dried filter cakes, detecting the content of aluminum chlorohydrate to be 98.6% by using a complexation method, detecting the content of sodium ions to be converted into the content of sodium chloride to be 0.47% by using an ion chromatography, detecting the content of phosphorus to be 19.7ppm by using an ammonium molybdate spectrophotometry, and obtaining the recovery rate of 98.4%;
s4, combining the filtrate and the washing liquid obtained in the step S3, carrying out reduced pressure distillation, and absorbing vacuum tail gas by cooled distilled hydrochloric acid to obtain 3574 g of 36.8% hydrochloric acid;
s5, neutralizing 104.3 g of residual liquid after distillation in the step S4 with sodium hydroxide, filtering, adding concentrated hydrochloric acid into filtrate to acidify until the pH value is 1, carrying out reduced pressure distillation, evaporating to remove water, adding 150 g of acetone, refluxing and dissolving the residue, filtering while the solution is hot, washing the solid with 50 g of hot acetone to obtain a sodium chloride solid and a phosphorus-containing flame retardant acetone solution, cooling to 5 ℃, filtering, and drying in vacuum to obtain 98.1 g of a solid flame retardant (compound I-2) (Mp 105-106 ℃), wherein the recovery rate is 94%. This flame retardant was dissolved in 500 g of water, and 15.5 g of aluminum hydroxide was added thereto, followed by refluxing for 4 hours, filtration and drying to obtain 97.9 g (yield 95.2%).
Flame retardancy test
And (3) testing flame retardance: in order to test the flame retardant performance of the flame retardant conveniently, epoxy resin is used as a polymer base material, specifically, bisphenol A epoxy resin (CYD-127) and a curing agent diaminodiphenylmethane (DDM) are taken, 100 g of the epoxy resin is added into the flame retardant obtained in the embodiment, the addition amounts of the flame retardant are respectively 10% and 15%, a high-speed dispersion machine is used for dispersing, 26 g of the curing agent is added, the temperature is raised to 145 ℃, the high-speed dispersion machine is used for dispersing continuously, the mixture is uniformly dispersed, the mixture is poured into a mold and placed into an oven, the temperature is kept at 160 ℃ for 4 hours, the sample is taken out of the mold after being cooled for testing, and the flame retardant data (the carbon residue rate and the oxygen index at 600 ℃) are measured as shown in Table 1.
TABLE 1
The flame retardant test data show that the flame retardant recovered by the method has excellent flame retardant performance which is equivalent to that of the same flame retardant produced normally.
Comparative example 1
The treatment of the phosphorus-containing complex salt was carried out according to the method reported in CN111689508A, as follows:
weighing 2000 g of water, heating to 80 ℃, taking 500 g of phosphorus-containing composite salt, adding the phosphorus-containing composite salt into 2000 g of water in batches, controlling the temperature of a reaction system to be 80 ℃, carrying out heat preservation reaction for 1 hour, introducing 350 g of hydrogen chloride, separating out solids, filtering, drying the solids at 70 ℃ in vacuum for 7 hours to obtain 102.6 g of solids, analyzing that the content of sodium chloride is 95.5%, the content of aluminum chlorohydrate is 3.8%, the content of total phosphorus is 0.278%, and reducing the content to 2780ppm, concentrating and crystallizing the filtrate at normal pressure, stopping concentrating when the temperature of the system is 110 ℃, cooling crystals, filtering, drying the solids at 70 ℃ in vacuum for 7 hours to obtain 494.6 g of solids, analyzing that the content of sodium chloride is 8.68%, the content of aluminum chlorohydrate is 90.0%, the content of total phosphorus is 0.52%, and reducing the content to 5200ppm.
Comparative example 2
This example provides a method of treating a phosphorus-containing complex salt, using substantially the same treatment procedure as in example 1, except that the substance added in S1 is not acrylic acid, but p-methylphenol. The specific implementation process is as follows.
S1, weighing 1000 g of phosphorus-containing composite salt in the same batch as a detection sample, adding the phosphorus-containing composite salt into 2100 g of a 4% hydrochloric acid solution in batches, then adding 100 g of p-methylphenol, and keeping the system temperature at about 50 ℃ in the adding process to obtain a first mixture;
s2, introducing 105 g of hydrogen chloride into the first mixture, continuously stirring for 30 minutes, heating to 80 ℃, preserving heat for 1 hour, filtering, pulping and washing a filter cake with 650 g of 20% hydrochloric acid, filtering and drying to obtain 295.3 g of sodium chloride, calibrating the content of the sodium chloride to be 99.38% by detecting sodium ions through an ion chromatography, measuring the content of phosphorus to be 19.2ppm by an ammonium molybdate spectrophotometry, and obtaining the recovery rate of the sodium chloride to be 94.9%;
s3, combining the filtrate obtained in the filtering step in the step S2, continuously introducing 720 g of hydrogen chloride, filtering, washing a filter cake by 1100 g of 35% hydrochloric acid, drying, weighing 1046.9 g of aluminum chloride hydrate, detecting the content of the aluminum chloride hydrate to be 97.9% by using a complexation method, detecting the content of sodium ions to be 0.41% by using an ion chromatography, detecting the content of phosphorus to be 15.4ppm by using an ammonium molybdate spectrophotometry, and recovering the recovery rate of the aluminum chloride hydrate to be 94.1%;
s4, combining the filtrate filtered in the step S3 with a washing solution, carrying out reduced pressure distillation, and absorbing vacuum tail gas by cooled distilled hydrochloric acid to obtain 3542 g of 36.7% hydrochloric acid;
s5, neutralizing 196.5 g of residual liquid obtained by reduced pressure distillation in the step S4 with sodium hydroxide, filtering, adding concentrated hydrochloric acid into filtrate to acidify until the pH value is 1, carrying out reduced pressure distillation, evaporating water, adding 100 g of ethanol to dissolve residues, filtering, and washing filter cakes with 40 g of ethanol to obtain sodium chloride solid; the filtrate and the washing liquid are combined to obtain phosphorus-containing flame retardant ethanol solution, after ethanol is removed by evaporation, 90.5 g of p-methylphenol is obtained by reduced pressure distillation, the distillate at 175-178 ℃ is collected under the vacuum degree of 5Pa to obtain 12.4 g of liquid flame retardant, the residual high boiling point distillate is 60.2 g, and the recovery rate of the converted phosphorus is 11.6%.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.
Claims (16)
1. A comprehensive recycling method of alkyl dichlorophosphine production byproducts, wherein the alkyl dichlorophosphine production byproducts comprise sodium chloride and aluminum chloride composite salts and alkyl dichlorophosphine, and the method is characterized by comprising the following steps of:
s1, reacting alkyl dichlorophosphine in the alkyl dichlorophosphine production byproduct with an olefinic acid compound in the presence of water to generate a phosphorus-containing flame retardant or an intermediate thereof, so as to obtain a first mixture containing the phosphorus-containing flame retardant or the intermediate thereof, sodium chloride and aluminum chloride;
s2, introducing hydrogen chloride and/or adding hydrochloric acid into the first mixture to enable the mass percentage of the hydrogen chloride in the mixture solution to reach 5% -15%, crystallizing and separating out sodium chloride, filtering, washing a filter cake with hydrochloric acid to obtain pure sodium chloride solid, wherein the filtrate is a second mixture containing a very small amount of sodium chloride, aluminum trichloride, a phosphorus-containing flame retardant or an intermediate thereof and hydrochloric acid;
s3, introducing hydrogen chloride gas and/or adding hydrochloric acid into the filtrate obtained after filtration in the step S2 to enable the mass content of hydrogen chloride in the mixture solution to be more than or equal to 35%, enabling aluminum chloride to be precipitated in the form of aluminum trichloride hydrate, filtering, washing a filter cake with hydrochloric acid, and drying to obtain aluminum trichloride hydrate, wherein the filtrate is a third mixture containing a phosphorus-containing flame retardant or an intermediate thereof, aluminum chloride, sodium chloride and hydrochloric acid;
s4, distilling and concentrating the third mixture obtained in the step S3 to obtain concentrated hydrochloric acid and a phosphorus-containing flame retardant mixed with aluminum chloride and sodium chloride or an intermediate thereof;
and S5, separating and removing aluminum chloride and sodium chloride from the phosphorus-containing flame retardant mixed with the aluminum chloride and the sodium chloride or the intermediate thereof to obtain the phosphorus-containing flame retardant or the intermediate thereof.
2. The comprehensive recycling method of alkyl dichlorophosphine production byproducts according to claim 1, wherein in step S1, the alkyl dichlorophosphine production byproducts, the olefinic acid compound and the dilute hydrochloric acid are mixed and reacted at a temperature of 40-100 ℃, and the mass percentage of the dilute hydrochloric acid is less than or equal to 10%.
3. The method for comprehensively recycling alkyl dichlorophosphine production byproducts according to claim 2, wherein in step S1, the alkyl dichlorophosphine production byproducts are added to the diluted hydrochloric acid in batches, the system temperature is kept at 40-100 ℃ in the adding process, and when the addition of the alkyl dichlorophosphine production byproducts is finished, an olefinic acid compound or an aqueous solution in which the olefinic acid compound is dispersed is added, and the mixture is stirred for reaction to obtain the first mixture.
4. The method for comprehensively recycling alkyl dichlorophosphine production byproducts according to claim 1, wherein in the steps S2 and S3, the hydrochloric acid for washing is concentrated hydrochloric acid with the mass percentage of 30-37%.
5. The method for comprehensively recycling alkyl dichlorophosphine production byproducts according to claim 1, wherein in step S1, the olefinic acid compound has a structure represented by the following general formula (1):
wherein R is 1 、R 2 、R 3 Independently hydrogen, C1-C12 branched or straight chain alkyl, C3-C12 cycloalkyl with a C1-C12 alkyl side chain, phenyl which is unsubstituted or substituted with one or more C1-C12 branched or straight chain alkyl groups.
6. The alkyl group of claim 5The comprehensive recycling method of the dichlorophosphine production by-product is characterized in that in the general formula (1), R 1 、R 2 、R 3 Independently hydrogen, methyl, ethyl, propyl, cyclopropyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, methylphenyl or ethylphenyl, wherein R 1 、R 2 、R 3 Of which at most only one is a cyclic substituent.
7. The method for comprehensively recycling the alkyl dichlorophosphine production by-products according to claim 5, wherein in step S1, the olefinic acid compound is acrylic acid and/or methacrylic acid.
8. The method for comprehensively recycling alkyl dichlorophosphine production byproducts according to claim 1, wherein the content of alkyl dichlorophosphine in the phosphorus-containing composite salt is obtained before step S1, and in step S1, the ratio of the alkyl dichlorophosphine to the olefinic acid compound is 1:1.01 to 1.3.
9. The method for comprehensively recycling alkyl dichlorophosphine production byproducts according to claim 8, wherein in step S1, the molar ratio of the alkyl dichlorophosphine to the olefinic acid compounds is 1: 1.01-1.1, and feeding.
10. The method for comprehensively recycling alkyl dichlorophosphine production byproducts according to claim 1, wherein in step S1, the usage amount of the dilute hydrochloric acid is 1-10 times that of the phosphorus-containing composite salt; and/or the reaction temperature is 45-60 ℃.
11. The comprehensive recycling method of alkyl dichlorophosphine production byproducts according to claim 1, characterized in that in step S1, the mass percentage of the dilute hydrochloric acid is 2-5%; and/or in the step S2, introducing hydrogen chloride to ensure that the mass percentage of the hydrogen chloride in the mixture solution reaches 6-10%; and/or in the step S3, introducing hydrogen chloride to ensure that the mass content of the hydrogen chloride in the mixture solution is 35-45%.
12. The method for comprehensively recycling alkyl dichlorophosphine production byproducts as claimed in claim 1, wherein in step S1, after the sodium chloride is crystallized and precipitated and before filtration, the system is kept at 70-90 ℃ for 1-2 hours.
13. The method for comprehensively recycling the alkyl dichlorophosphine production by-product according to claim 1, wherein the step S5 further comprises:
s50: adding sodium hydroxide to the phosphorus-containing flame retardant mixed with the aluminum chloride and the sodium chloride or the intermediate thereof obtained in the step S4 to allow the aluminum chloride in a dissolved state to generate sodium chloride and aluminum hydroxide to obtain a mixture containing aluminum hydroxide, sodium chloride, the phosphorus-containing flame retardant or the sodium salt of the intermediate thereof, and filtering to obtain a filtrate which is an aqueous solution of the phosphorus-containing flame retardant or the sodium salt of the intermediate thereof and the sodium chloride;
s51: and (2) adding hydrochloric acid into the filtrate obtained in the step (S50) for acidification so as to enable the phosphorus-containing flame retardant or the intermediate sodium salt thereof to be dissociated into the phosphorus-containing flame retardant or the intermediate thereof, then concentrating until no water exists to obtain the phosphorus-containing flame retardant or the phosphorus-containing flame retardant intermediate and sodium chloride, adding an organic solvent, uniformly stirring, filtering, concentrating the filtrate, carrying out reduced pressure distillation or recrystallization to obtain the phosphorus-containing flame retardant or the intermediate thereof, washing the filter cake with the organic solvent, and drying to obtain sodium chloride.
14. The integrated recycling method of alkyl dichlorophosphine production byproducts according to claim 13, further comprising one or more of the following steps:
s7, applying the aluminum chlorohydrate obtained in the step S3 to the casting and sewage treatment industries;
s8, further separating the concentrated hydrochloric acid obtained in the step S4 into hydrogen chloride gas and dilute hydrochloric acid for use in the step S1;
s9, dissolving the sodium chloride obtained in the step S5 with water to obtain a sodium chloride aqueous solution, returning to the step S1, mixing the sodium chloride aqueous solution with dilute hydrochloric acid, and dissolving the compound salt;
s10, returning the filter cake filtered in the step S50, namely the aluminum hydroxide, to the step S2 for generating aluminum chloride;
and S11, further preparing the phosphorus-containing flame retardant intermediate obtained in the step S51 into a phosphorus-containing flame retardant.
15. The method of claim 1, wherein said alkyl dichlorophosphine is methyl dichlorophosphine, and further comprising: and S6, applying the sodium chloride solid obtained in the step S2 to a production process of the methyl dichlorophosphine.
16. A method for producing an alkyl dichlorophosphine comprising: (1) Obtaining an alkyl dichlorophosphine and a sodium chloride-aluminium chloride complex salt by-product containing the alkyl dichlorophosphine, characterized in that the production method also comprises (2): the comprehensive recycling method of any one of claims 1 to 15 is adopted to recover and obtain sodium chloride, aluminum chlorohydrate, phosphorus-containing flame retardant or intermediate thereof.
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