A fully continuous flow production method of tris(1-chloro-2-propyl) phosphate

Abstract

The present invention relates to a fully continuous production process of tris(1-chloro-2-propyl) phosphate. In the present invention, the reaction stage and the post-treatment stage are carried out continuously and uninterruptedly as an overall process. The raw materials phosphorus oxychloride, propylene oxide and catalyst continuously enter the reactor feed port, and the finished product of tris(1-chloro-2-propyl) phosphate meeting the commercial standard is continuously obtained at the reactor outlet, realizing the rapid preparation of high-quality tris(1-chloro-2-propyl) phosphate (TCPP) finished product. The fully continuous production process of the present invention not only realizes high-efficiency production, high-quality finished product and stable storage, the TCPP finished product does not contain aldehyde impurities, does not turn sour, and does not contain metal cations corresponding to the catalyst, but also the process generates less waste water and has a low phosphorus content, which is beneficial to environmental protection and suitable for safe industrial production.

Description

[0001] This application is a divisional application of the application with the filing date of May 7, 2018, application number 201810427273.2, and invention title "A fully continuous production process of tris(1-chloro-2-propyl) phosphate". Technical Field

[0002] The present invention relates to the field of chemical additive flame retardants, and specifically relates to a fully continuous production method for preparing tris(1-chloro-2-propyl) phosphate (TCPP). Background Art

[0003] Tris(1-chloro-2-propyl) phosphate, also known as tris(2-chloroisopropyl) phosphate, trichloropropyl phosphate, etc., abbreviated as TCPP, is a phosphorus-based additive flame retardant with significant flame retardant effects and is widely used in various polymer materials such as polyurethane flexible foam plastics, rigid foam plastics, epoxy resins, and phenolic resins.

[0004] The production process of TCPP mainly includes a reaction stage and a post-treatment stage, and the brief process is as follows:

[0005]

[0006] As known to those skilled in the art, the current industrial process for preparing TCPP is as follows: under anhydrous and oxygen-free conditions, the catalyst is dissolved in the raw material phosphorus oxychloride (POCl3), propylene oxide (PO) is slowly added dropwise at 40-60°C, after the reaction is initiated, the reaction temperature is controlled at 55-60°C and propylene oxide is continued to be added dropwise, after the addition is completed, the temperature is kept for several hours to complete the reaction, and then the remaining propylene oxide is removed under vacuum to obtain a crude TCPP product. The crude product is then added to an alkali solution, and the crude product is alkali-washed at 60-90°C, and after standing and stratifying, the oil phase is washed with water to neutrality, and after standing and stratifying, the oil phase is placed under vacuum to remove the residual water, and a TCPP finished product that meets commercial standards can be obtained. The slow dripping of propylene oxide and the reaction heat preservation time in the reaction stage are more than ten to dozens of hours in total. The total time of multiple stirring and washing included in the alkali washing and water washing in the post-treatment stage is more than several hours. In addition, the vacuum PO removal operation after the reaction is completed, the dehydration and drying after washing, etc., the entire production process takes a long time. And the raw material propylene oxide (PO) used in the reaction has a boiling point of 34.24 ° C, is volatile, lower than the normal reaction temperature of phosphorus oxychloride and propylene oxide, and is easy to open the ring polymerization under the action of the catalyst, releasing a large amount of heat, and the explosion limit is 3.1-27.5% (VOL). It is a flammable, explosive, dangerous, and toxic chemical reagent; the raw material phosphorus oxychloride is a colorless and transparent chemical raw material, which is strongly fuming, hygroscopic, and highly corrosive. It releases heat violently when it comes into contact with water, alcohol and other substances, and has a high reactivity. These two raw materials will release a lot of heat at the moment of contact in the reaction, which may cause impurities to be generated by overheating at the least, or cause the reaction liquid to coke and even cause an explosion accident in severe cases. Therefore, the current production process is to slowly add propylene oxide to phosphorus oxychloride under strong heat exchange and relatively low temperature conditions, and remove the heat generated by the reaction in time. The addition time and the insulation time after the addition are several hours respectively, so the TCPP production process has very high requirements for heat transfer efficiency. Since in the production process, a large amount of unreacted raw materials stay in the device, if leakage occurs (such as condensed water seeping into the reactor after aging), the highly acidic liquid may escape, which has a very high safety hazard. The dropwise addition operation has no direct relationship with the speed and flow rate of material dropwise addition or addition of the reaction equipment. The most obvious feature of the dropwise addition is that at any time during the dropwise addition process, at least one reaction raw material (for example, propylene oxide) is insufficient, and it is necessary to dropwise add after a period of time to reach the sufficient amount of each reactant in the reaction.For example, in Example 1 of Chinese Patent CN106565773A, it is mentioned that in a 5000L reactor, 600 kg of the bottom residue from the previous batch is left, 2600 kg of phosphorus oxychloride is charged, 5 kg of phosphorus trichloride and 6 kg of pyrophosphoryl chloride are added, and after adding 7 kg of aluminum trichloride, propylene oxide is then introduced. The temperature is controlled at 35 - 40 °C and the flow rate is controlled at 50 - 100 kg / h (at the initial stage of the reaction); the temperature is 45 - 50 °C and the flow rate is controlled at 100 - 300 kg / h (at the middle stage of the reaction); the temperature is 50 - 55 °C and the flow rate is controlled at 300 - 400 kg / h (at the later stage of the reaction). Although the addition of propylene oxide is maintained at a relatively high flow rate during the production process, the propylene oxide is added in segments throughout the addition process, which also belongs to the way of dropwise addition.

[0007] Using the existing industrial production process, the TCPP finished products that meet the commercial standards obtained after the post-treatment stage are prone to unstable product quality and high impurity content. Specifically, the acid value of the TCPP finished products will change during storage, transportation or use by downstream users, resulting in unstable finished product quality, and there are obvious fluctuations in the quality and purity of the finished products. The main indicators are the acid value and the content of aldehyde impurities in the TCPP finished products, and the content of 2-methyl-2-pentenal is the main evaluation index for aldehyde impurities. The acid value refers to the number of milligrams of potassium hydroxide (KOH) required to neutralize all acidic components in 1 gram of the TCPP finished product, which can be expressed as mgKOH / g, and it reflects the amount of acidic substances in the TCPP finished product. The larger the acid value, the greater the risk to downstream use, which will reduce the product quality of downstream products, and in severe cases, it will cause the production of downstream products to fail. The TCPP finished products produced by the existing process will slowly hydrolyze during storage, transportation or use by downstream users, generating acidic substances. This acidic substance has an autocatalytic function, resulting in an accelerated increase in the acid value. This phenomenon of increasing acid value is called acid reversion. The higher the degree of acid reversion, the worse the stability of the TCPP finished product. The occurrence of acid reversion poses a great threat to the use of TCPP, but the TCPP finished products prepared by the current production process and the existing technology cannot avoid this problem. Since this problem cannot be avoided at present, downstream manufacturers have to accept and use TCPP finished products with trace acid reversion, and can only overcome the adverse effects caused by acid reversion by shortening the storage time of TCPP and adjusting their own product production formula and process, which actually causes many inconveniences and potential hazards to downstream customers. Even if TCPP finished products with a low acid value are prepared, acid reversion will still inevitably occur during storage, transportation or use by downstream users. Among them, in order to simply and quickly detect whether the TCPP finished product has acid reversion and the degree of acid reversion, it can be characterized and reflected by using the aging experiment method. The specific method is as follows: Take 60 g of the sample into an aging bottle with a volume of 60 ml, seal it well and put it into an oven at a constant temperature of 100 °C for 3 h, and compare the acid value changes before and after. The acid value of the product before aging is called the finished product acid value, and the acid value of the product after aging is called the acid value after aging. The difference or ratio between the acid value after aging and the finished product acid value can reflect the degree of acid reversion: the larger the difference, the higher the degree of acid reversion, the worse the product stability, and the lower the product quality. Correspondingly, the smaller the difference, the lower the reaction degree, the higher the product stability, and the higher the product quality; or the larger the ratio, the higher the degree of acid reversion, the worse the product stability, and the lower the product quality. Correspondingly, the closer the ratio is to 1, the lower the reaction degree, the higher the product stability, and the higher the product quality.

[0008] The catalysts used in the reaction stage of TCPP are usually Lewis acid catalysts or corresponding Lewis acid ionic liquid catalysts. For example, the catalysts are selected from one or more of aluminum trichloride, titanium tetrachloride, tetrabutyl titanate, zinc chloride, magnesium chloride, iron chloride or corresponding ionic liquid catalysts. After the reaction stage, post-treatment is required to remove the residual catalysts. The use of lye in the post-treatment stage can remove most of the catalysts, but cannot completely remove the metal cations corresponding to the catalysts (for example, when the catalyst is AlCl3, the corresponding metal cation is Al 3+ 3+

[0009] The aldehyde impurities are mainly caused by the long production process, which leads to the oxidation of phosphorus oxychloride by propylene oxide during the production process. Among them, 2-methyl-2-pentenal has a special stench and cannot be completely removed after the post-treatment stage. It will bring sensitive odors into the downstream finished products, seriously affecting the quality of downstream products. Therefore, there are requirements for the content of this aldehyde in industrial production. The current production process generally has a residue of 100-200 ppm. Some reports show that after TCPP undergoes conventional post-treatment and then further post-treatment operations such as additional oxidation and addition of additives, the aldehyde impurities can be reduced to about 10 ppm. However, the existing post-treatment process cannot completely remove the aldehyde impurities and still has a certain impact on downstream products. In addition, reducing the residue of aldehyde impurities in the prior art requires multiple purification steps, which can only reduce the residue amount, but cannot produce TCPP finished products without aldehyde impurities, let alone directly produce TCPP finished products without aldehyde impurities. More purification steps are required to achieve the purpose of reducing the aldehyde value, and the aldehyde impurities cannot be completely removed, which increases the time cost and treatment cost.

[0010] Currently, the requirements for TCPP finished products meeting the marketable standards are: acid value (mg KOH / g) ≤ 0.1, water content (wt.%) ≤ 0.1, color (APHA) ≤ 50. However, the prior art cannot prepare TCPP finished products with stable acid values (non-acid reflux), a content of aldehyde substances of 0 (aldehyde-free), and no metal cations corresponding to the catalysts (the content of the metal cations is 0).

[0011] In order to obtain a TCPP finished product that meets the commercial standards, after the reaction stage, the post-treatment of the TCPP crude product is required. Currently, the post-treatment process in the industry uses a washing process of first alkali washing and then water washing to obtain a finished product with a low acid value. Some processes also add an acid washing process before alkali washing in order to obtain a finished product with higher quality and fewer impurities. Since the TCPP finished product is unstable and prone to hydrolysis in strongly acidic and strongly alkaline aqueous solutions, in order not to reduce the yield, the concentrations of the acids and alkalis used in both acid washing and alkali washing cannot be too high. However, to ensure the washing effect, the dosages of the acid solution and the alkali solution are not small, and the amount of water used for water washing is also large, directly resulting in a high level of wastewater produced during the production process, and the wastewater treatment cost also increases significantly. These are all well-known to those skilled in the art. Moreover, due to the long post-treatment time, TCPP decomposes in an alkaline environment, resulting in a relatively high phosphorus content in the post-treatment wastewater. Generally, it is above 2000 ppm. The control of the organic phosphorus content in the wastewater is very strict environmentally, and the discharge standard is only 8 ppm. Corresponding treatment must be carried out to meet the discharge standard before it can be discharged, which also significantly increases the production cost. The current production process cannot significantly reduce the water consumption and the organic phosphorus content in the washing water, which directly leads to an increase in production cost and a decrease in the production efficiency of the finished product.

[0012] Currently, the industrial production process of TCPP still adopts the traditional production method from reaction to post-treatment. Especially in the reaction stage, propylene oxide is slowly added dropwise. At the same time, the current TCPP production process uses traditional reaction equipment (such as reaction kettles, stirred reactors, cascade reactors, liquid distributors, reaction towers, etc.), with multiple stops and waits in the middle, which all make the entire production process take a long time to complete, resulting in unstable quality of the finished product and obvious fluctuations, such as the size of the acid value, the content of aldehyde impurities, and the residual amount of metal cations. Although there are reports on the continuous production process of TCPP at present, the currently reported continuous production process of TCPP still has a long way to go in realizing industrialization, or has its fatal defects.

[0013] The production process of TCPP refers to the process in which raw materials go through the reaction stage to obtain the crude TCPP product, and the crude TCPP product goes through the post-treatment stage to obtain the commercially available TCPP product with good quality and high purity. The production process, including the processes of the reaction stage and the post-treatment stage, is considered as an overall process. Each process in the production process has specific process parameters, such as time, temperature, pressure, etc. The total time required to complete all production processes is called the total production process time (including the time of the reaction stage and the time of the post-treatment stage). The total production process time can directly evaluate the efficiency of the production process, that is, the shorter the total production process time, the higher the production process efficiency. In a process that includes multiple reaction or operation steps, if several of these steps are continuous or just simply connect the steps in the original batch process, and there are production processes such as stops and waits in between, this process is still a non-continuous flow production process. Its typical situation is the use of traditional chemical production equipment such as stirring paddles, reaction kettles or series reaction kettles, reactors with stirring, cascade reactors, liquid distributors, reaction towers, etc. Another intuitive manifestation is that the total production process time of non-continuous flow production processes is relatively long, generally several hours, more than ten hours, dozens of hours, and in some individual reactions, it even lasts for several days. This will reduce the production efficiency of the entire process and also bring certain safety risks. Only when all steps are continuous and the materials flow continuously throughout the entire process without stops or waits, and the entire process includes the processes of the reaction stage and the post-treatment stage, that is, continuously adding raw materials, continuously going through the reaction stage and the post-treatment stage, and continuously obtaining products that meet the commercial standards, can it be called a fully continuous flow production process (or a fully continuous process for the entire process), that is, there is no stop or wait in the reaction stage and the post-treatment stage. The production process of TCPP, including the processes of the reaction stage and the post-treatment stage, is considered as an overall process; the continuous flow production process of TCPP means that the reaction stage and the post-treatment stage are continuously and uninterruptedly carried out as an overall process, and raw materials continuously enter the reactor feed port, and commercially available TCPP products that meet the standards are continuously obtained at the reactor outlet. The total production process time of TCPP, including the total time of the reaction stage and the post-treatment stage, that is, the total time from phosphorus oxychloride and propylene oxide entering the reactor until commercially available TCPP products that meet the standards are obtained. The continuous flow process for TCPP production means that the entire process of the reaction stage and the post-treatment stage is continuously flowing, that is, continuously adding phosphorus oxychloride and propylene oxide as raw materials, without any stops and waits in the middle process, and continuously obtaining commercially available TCPP products that meet the standards.

[0014] European Patent EP0398095B1 discloses the reaction of phosphorus oxychloride with propylene oxide in the presence of TCPP as a solvent and titanium tetrachloride as a catalyst, followed by post-treatment such as strong acid washing, liquid separation using a separating funnel, water washing, alkali washing, and distillation drying to obtain the finished product. Although this method uses a continuous production process to prepare TCPP, due to operations such as liquid separation and cooling during the process, and the use of traditional reaction equipment (including cascade reaction clusters, stirred reaction kettles, glass flasks, etc.), multiple stays and waits are required, so it is a non-continuous flow production process. The patent mentions that a residence time of 0.5 - 1.6 hours can obtain high-quality TCPP finished products. More specifically, in the examples of this patent, three stirred reaction kettles with heat exchange devices are used, and the residence time in each reaction kettle is maintained at 45 minutes. The residence time mentioned only refers to the residence time of the reaction. Coupled with subsequent post-treatment processes such as pickling, alkali washing, water washing, and drying, the total production process time will be significantly extended, and the entire production time will be more than several hours. Therefore, the technical solution disclosed in this patent is a non-continuous flow production process, with a long total reaction time and no obvious improvement in reaction efficiency. At the same time, strong acid washing is required during the post-treatment of this process, but TCPP products have very poor stability under strong acidic conditions, which will cause the product to decompose to generate by-products, resulting in a decrease in product yield and quality, and an increase in the amount of alkali used. In addition, using TCPP as a solvent in the reaction greatly increases the production cost and reduces the production efficiency compared to the usual solvent-free conditions. Chinese Patent CN1034206A discloses a continuous manufacturing method of α-haloalkyl phosphate esters (such as TCPP). That is, under the action of a mixed catalyst of beryllium compound and phosphorus trichloride, multi-stage continuous reaction tanks are used to continuously carry out alkali treatment and water washing in a countercurrent manner, and finally vacuum evaporation and dehydration are carried out to obtain the product. Compared with the prior art, although this method uses a continuous process to produce TCPP, a large number of traditional reactors such as reaction tanks, settlers, and stirring shafts are used during the process, and there will inevitably be a stay and wait process in the middle. The time used is not short enough and the production efficiency is not high enough, so it still belongs to the aforementioned non-continuous flow production process. This technology also mentions that the total reaction time of TCPP is relatively long, all reaching more than several hours. In addition, the beryllium oxide used in this patent is a highly toxic substance, so this technical solution is not suitable for widespread use. It can be seen that the technical solution described in this patent is neither a continuous flow production process, nor has it made obvious technical improvements in terms of production efficiency, and a highly toxic substance is used as a catalyst during the reaction process, which greatly restricts its industrial promotion and application.

[0015] In summary, the existing production process for preparing TCPP is a non - continuous - flow production process. That is, the reaction stage and the post - treatment stage of the process for preparing TCPP are not continuously integrated and matched together, but are two separate independent processes. That is, there are stops or waits in the reaction stage and the post - treatment stage. The improvements to the existing production process for TCPP are respectively targeted at the reaction stage and the post - treatment stage. The typical technologies are as follows:

[0016] US Patent US7820845B2 mentions that the product (phosphite) obtained after the continuous reaction of phosphorus trihalide and aluminum trichloride is transferred into a reactor batch - wise or continuously and reacts with an epoxidizing agent (i.e., epoxide), and finally the crude product containing the remaining epoxidizing agent is washed with an alkali solution. This patent points out that to ensure a continuous reaction state, the flow rate of phosphorus trihalide should be 100 liters per hour to 1000 liters per hour, preferably 200 liters per hour to 500 liters per hour. This method only achieves continuity in the reaction - stage process and does not involve the post - treatment - stage process. It is not a fully continuous - flow production process for TCPP. At the same time, in Examples 1 and 2 of this patent, the reaction time has reached 6 hours. If the post - treatment stage is to be completed, the total production - process time will be even longer, which obviously greatly reduces the production efficiency. This patent uses a non - continuous - flow production process.

[0017] The production processes of phosphates or phosphites have certain similarities. Their reaction steps are mainly the ring - opening addition reaction of phosphorus trihalide or phosphoryl halide with an epoxide to obtain various phosphates or phosphites. However, the structural differences existing in different phosphate or phosphite derivatives (such as different types, numbers, and substitution positions of substituents) will cause the physical and chemical properties (such as melting and boiling points, solubility, reaction activity, and stability, and even reaction mechanisms and selectivities, etc.) of the raw materials, reaction intermediates, and products required for synthesizing various phosphate or phosphite derivatives to be very different. As a result, the corresponding synthetic routes and production processes are quite different, making it difficult to learn from each other and impossible to transplant directly. It is necessary to specifically design and develop targeted process procedures, conditions, and parameters according to the physical and chemical properties of the specific compounds involved in the process. Therefore, for the continuous - flow production process of TCPP involved in this patent, the production processes of different phosphates or phosphites cannot be directly borrowed and have no reference value.

[0018] There are also attempts at continuous post-processing processes for TCPP in related literature. Chinese patent CN105837621A discloses a post-processing device and method for a phosphate flame retardant, in which the crude phosphate product is sequentially passed through an alkali washing tower and a water washing tower for countercurrent contact and then added to a thin film evaporator or a molecular distillation evaporator to obtain a finished product, wherein the contact time for alkali washing and water washing is 7 to 20 minutes and 8 to 30 minutes, respectively. This patent only realizes the continuity of the post-processing stage, but does not integrate the post-processing stage with the reaction stage to achieve continuity, so it is not a full continuous flow production process for TCPP. In addition, this patent only completes two-step countercurrent washing of alkali washing and water washing, and the operation time is at least 15 minutes. Although the time has been shortened compared with kettle washing, the production efficiency still needs to be improved. Because this method is not continuous from reaction to post-processing, a non-continuous flow production process is used, and the finished product obtained will inevitably have characteristics such as acid regurgitation and contain aldehyde impurities, and the product quality needs to be improved.

[0019] Through the analysis of the above-mentioned comparative documents, it can be seen that although the existing technology has achieved continuity at a certain stage, it still takes a long time to complete the entire reaction. In addition to being unable to achieve an efficient and fully continuous flow production process for TCPP, the existing technology also has many problems that need to be solved, such as a large number of impurities, poor storage stability and easy acid regurgitation, large wastewater discharge and excessive phosphorus content, and potential safety hazards.

[0020] As is known to all, due to the long reaction time of the existing TCPP production technology, part of the propylene oxide will be oxidized by phosphorus oxychloride into aldehyde compounds during the production process, among which 2-methylpentanal is the main impurity. This aldehyde has a special odor, has good compatibility with TCPP, is almost insoluble in water, and will still have residues even after a series of post-treatments such as alkali washing, water washing and dehydration. Through the detection of existing finished products, it is found that the residual amount of 2-methylpentanal is not less than 100ppm, and the residual amount of some finished products is even as high as 200-300ppm, which seriously affects the quality of TCPP finished products.

[0021] Chinese patent CN100549130C discloses a method for preparing TCPP and removing aldehyde impurities, that is, after obtaining a crude TCPP product, adding a hydroxylamine hydrochloride solution of an aldehyde compound equivalent to react with the by-product aldehyde to generate a water-soluble oxime, and removing the oxime through a subsequent water washing process, thereby reducing the content of aldehyde impurities in the TCPP finished product. The shortcomings of this method are: first, it is necessary to add an additional water washing operation, which increases the time cost and waste water, which is neither economical nor environmentally friendly; second, hydroxylamine hydrochloride is incompatible with the product, and the reaction process is slow, which may lead to incomplete removal of aldehyde impurities and reduce product quality; third, hydroxylamine hydrochloride has a high cost, and the HCl part thereof will decompose the TCPP finished product to reduce the yield.

[0022] In addition to adding hydroxylamine hydrochloride solution, aldehyde impurities can also be removed by adding an oxidizing agent. In Chinese Patent CN101775031A, high-valent oxides or peroxides composed of elements such as Mn, Cr, Fe, O, S, Cl, Br, I, etc., or their acids and potassium salts, sodium salts, etc. formed by the acids are used to remove the odor of TCPP in aqueous solution. Chinese Patent CN102002068A directly uses ozone to oxidize aldehyde substances that emit odors to achieve the purpose of deodorization. Chinese Patent CN102775439B discloses a preparation method of TCPP. In the post-treatment process, the crude product is treated with an organic peroxide, and the aldehyde substances in the crude product are oxidized into acidic substances by the oxidizing property of the peroxide. The oxidation temperature is 60-80°C, and then it is further subjected to alkali washing, water washing and vacuum dehydration to obtain a low-odor product. This patent introduces a new organic compound (organic peroxide) in the treatment process. Incomplete treatment will lead to a decline in the quality of the TCPP finished product, directly affecting the quality of the TCPP finished product. In addition, if the amount of peroxide added is too much, or the reaction conditions are not precisely controlled, there is a risk of over-oxidation and the generation of new impurities. As is well known, organic peroxides are a class of flammable and explosive compounds, especially under heating conditions (this patent uses 60-80°C), and the risk coefficient doubles. The method provided by this patent has certain risks during use. The common problem with such methods is that an additional step is required to remove acidic substances, which brings many problems such as increasing costs by adding additives, increasing the investment cost of other equipment, increasing the process time and reducing the process efficiency, and the residue of additives will affect the quality of the finished product, etc.

[0023] During the storage and use of TCPP finished products produced by the existing process, acid reflux will occur. If the TCPP finished product with acid reflux phenomenon is used in the combined polyether formula, since the acidic substances generated in TCPP will further neutralize the amine catalysts in the combined polyether, the combined polyether formula will be partially or completely damaged, resulting in the inability to produce polyurethane foams with qualified quality and performance, and even the process of producing foams will completely fail. Thus, it can be seen that the stability of TCPP finished products is very important for downstream use, especially the stability of the acid value is more significant, which will directly affect the benefits of downstream manufacturers. If the acid reflux phenomenon can be avoided, the reliability of TCPP finished products in use will be greatly improved.

[0024] Chinese Patent CN103408584A mentions a method for preparing highly hydrolysis-resistant TCPP, that is, adding the crude TCPP product into water, hydrolyzing it under acidic conditions, and then obtaining highly hydrolysis-resistant TCPP through washing, dehydration, and filtration. The hydrolysis temperature under acidic conditions is 0 - 10°C, the pH value is 2 - 4, the temperature is adjusted to -5 - 50°C under strong stirring, acid is added to adjust the pH ≤ 5, the hydrolysis reaction lasts for 60 - 180 minutes, and the pH value is adjusted to 8 - 9 with dilute alkali, and the temperature is adjusted to 50 - 90°C. After standing and separating layers, it is washed with deionized water, dehydrated by vacuum distillation, and then filtered to obtain the highly hydrolysis-resistant product. In order to obtain a product with good thermal stability, this patent needs to additionally add extra acid to strictly adjust the pH of the reaction solution, which makes the process operation troublesome, requires high temperature control during the pickling process, has a long residence time, and affects the product yield. Even though this patent has prepared a highly hydrolysis-resistant TCPP product with a low acid value, the phenomenon of acid return still cannot be avoided. Although Chinese Patent CN106699804A discloses a method for producing TCPP with good thermal storage stability, that is, heating phosphorus oxychloride and a catalyst (simultaneously containing an alcohol group and a metal) to 65°C at a rate of 10°C / min, adding an auxiliary agent dropwise, after holding for 30 minutes, cooling to 40 - 45°C and adding propylene oxide dropwise, and aging for 4 hours, where the auxiliary agent is n-butylpyridinium chloride. Although the reaction solution obtained by this method has a long thermal storage time, since it has not undergone more treatment, the resulting finished product still contains substances such as catalysts, auxiliary agents, and impurities that will affect downstream use. Chinese Patent CN103833784B discloses using a catalyst containing a metal and an alkyl group, heating to 60 - 80°C for aging after adding the raw materials dropwise, and discharging when the acid value of the aging solution is ≤ 0.2 mgKOH / g after 3 hours. Similarly, although the resulting finished product has good thermal storage stability, the corresponding catalyst and generated impurities are not removed, affecting the subsequent use of TCPP. It can be seen that in terms of improving the stability of the TCPP finished product in the prior art, special treatment steps are basically added, but these technical solutions will reduce the quality of the TCPP finished product in some aspects, increase the production time and raw material cost of the TCPP finished product. In addition, the prior art cannot solve the problem of acid return of the TCPP finished product.

[0025] The methods in the prior art for improving the quality of the TCPP finished product in the post-treatment process only improve a certain performance, such as reducing the acid value, reducing the content of aldehyde impurities, etc., but cannot simultaneously achieve the comprehensive improvement of multiple performances, and cannot produce a finished product without acid return and without aldehyde impurities. The post-treatment methods used in the prior art are to add steps or add new substances, resulting in increased costs, long time consumption, low efficiency, and the added new substances will inevitably affect the quality of the TCPP finished product. More importantly, the prior art has no solution to the acid return of TCPP. In addition, the post-treatment process and the reaction process in the prior art are not integrated and are two separate independent processes. The processes and equipment used are different, resulting in low production efficiency and increased costs.

[0026] In addition, the existing production process also has the problem of long post-treatment process time, large water consumption, and high phosphorus content of washing wastewater, which is difficult to be harmlessly treated. The wastewater obtained by the existing process cannot be directly applied because it contains a variety of organic and inorganic impurities. It generally needs to be subjected to biochemical harmless treatment and can only be discharged after reaching the standard, which increases the cost of wastewater treatment. At the same time, due to the high phosphorus content, when the existing manufacturers treat phosphorus-containing washing wastewater, they generally need to dilute it first and then perform biochemical treatment, which invisibly increases the amount of wastewater and further increases the treatment cost. Due to the large amount of wastewater, wastewater treatment and recovery account for a large proportion of the entire production cost of TCPP. Generally, the production water and wastewater treatment costs will account for 20-30% of the entire TCPP production cost. Excessive water consumption and treatment volume will directly lead to excessive production costs and reduce profits.

[0027] In addition, since the reaction stage and the post-processing stage of the prior art are two separate processes that are not continuously integrated and matched together, the prior art is unable to control the differences between different batches of crude products obtained in the reaction stage within an extremely small range, resulting in the inability to accurately adjust the post-processing time and the amount of alkali solution according to the actual situation of each batch of crude products. Only sufficient post-processing time and sufficient alkali solution can be used to ensure that the crude products of poorer batches become qualified commercial products after post-processing, thereby reducing the risk of unqualified products. However, compared with the crude products of better batches, it will cause a waste of post-processing time and a waste of alkali solution, increasing production costs and environmental pollution.

[0028] In summary, although some attempts have been made in the TCPP continuous production process, including continuous synthesis and continuous post-treatment, which have been improved compared to the kettle process, the following major problems still exist:

[0029] 1. Failure to achieve a simple and efficient production process from raw materials to qualified commercially available finished products, and the production process is complicated and requires multiple stops and waiting;

[0030] 2. The reaction stage and post-processing stage are not continuously integrated together, but are two independent processes. There is no one set of equipment to directly realize the production and post-processing process of TCPP, resulting in low production efficiency;

[0031] 3. The total process time is too long and the production efficiency is low;

[0032] 4. It is necessary to add additional steps to deal with aldehyde impurities in the finished product, which increases production costs and easily introduces new impurities, affecting the quality of the finished product and subsequent use;

[0033] 5. The finished product will have different degrees of acid regurgitation, which will affect downstream use;

[0034] 6. During the post-treatment process, a large amount of wastewater with a high phosphorus content is generated, which is costly to treat and difficult to recycle.

[0035] In the prior art, it is still impossible to obtain a TCPP product with a stable acid value (non-reverting), a content of aldehyde substances of 0 (aldehyde-free), and no metal cations corresponding to the catalyst (the content of the metal cations is 0), and no process has been developed that is simple, efficient, environmentally friendly in the production process and can ensure high-quality products, that is: the reaction process and the post-treatment process are continuously integrated and matched together, and a TCPP product meeting the commercial standards can be simply and efficiently obtained from the raw materials, while also taking into account the high quality of the product (aldehyde-free impurities, non-reverting), the environmental friendliness of the process (reducing the phosphorus content and the total amount of wastewater in the wastewater), and the low cost (no additional impurity removal steps are required). Summary of the Invention

[0036] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a fully continuous flow production process for TCPP, that is, the reaction stage and the post-treatment stage are continuously and uninterruptedly carried out as an overall process. Raw materials (POCl3, PO, catalyst) continuously enter the reactor feed port, and a TCPP product meeting the commercial standards is continuously obtained at the reactor outlet, realizing the rapid preparation of high-quality tris(1-chloro-2-propyl) phosphate (TCPP) products. The fully continuous flow production process for TCPP of the present invention not only realizes high-efficiency production, high-quality products and stable storage, the TCPP product is aldehyde-free and non-reverting, but also the process generates less wastewater with a low phosphorus content, which is beneficial to environmental protection and suitable for safe industrial production.

[0037] The continuous production process means that each production step in the production system is connected to each other during the production process, ensuring continuous operation as a whole, but allowing for waiting and staying in each step. As a kind of continuous process, the fully continuous flow production process is a fast and efficient full-process continuous process, which has the characteristics of short time, high efficiency, easy operation, etc. During the process, raw materials are continuously added without interruption, and products are continuously produced without interruption. During the process, the materials (i.e., the reaction mixture containing raw materials, intermediates, products, solvents, etc.) are continuously flowing without interruption or waiting, and the production and post-treatment processes are continuous and uninterrupted, that is, products meeting the commercial standards are continuously produced, which is a "production line" type of chemical production process. When the process operation reaches a steady state, the state parameters such as the composition and temperature of the materials at any position in the reactor do not change with time, which is a steady-state process, so both the production process and the product quality are stable. The present invention adopts the following technical solutions:

[0038] The present invention provides a fully continuous production method for tris(1-chloro-2-propyl) phosphate finished products. The production method is carried out in an integrated continuous flow reactor. The production process includes a reaction stage and a post-treatment stage, and the reaction stage and the post-treatment stage are carried out continuously and without interruption. Propylene oxide, phosphorus oxychloride solution containing a catalyst, alkali solution, and water are continuously added to the feed inlet of the integrated continuous flow reactor, and tris(1-chloro-2-propyl) phosphate finished products are continuously obtained at the discharge outlet of the integrated continuous flow reactor.

[0039] The integrated continuous flow reactor includes a reaction unit and a post-treatment unit.

[0040] The reaction unit and the post-treatment unit each include one or more functional units, and the functional unit includes a temperature zone and a reactor module or a group of reactor modules.

[0041] The reaction unit includes three temperature zones: temperature zone 1, temperature zone 2, and temperature zone 3.

[0042] The process temperature of the temperature zone 1 is 0 to 200 °C.

[0043] The process temperature of the temperature zone 2 is 30 to 150 °C.

[0044] The process temperature of the temperature zone 3 is 30 to 200 °C.

[0045] The flow rate of the phosphorus oxychloride solution containing a catalyst is 0.1 to 2 L / h.

[0046] The flow rate of the propylene oxide is 0.2 to 6.0 L / h.

[0047] Preferably, the post-treatment unit includes three temperature zones: temperature zone 4, temperature zone 5, and temperature zone 6.

[0048] The process temperature of the temperature zone 4 is 30 to 200 °C.

[0049] The process temperature of the temperature zone 5 is 30 to 200 °C.

[0050] The process temperature of the temperature zone 6 is 30 to 200 °C.

[0051] Preferably, the dosage of the catalyst is 0.01% to 1% of the mass of phosphorus oxychloride.

[0052] Preferably, the dosage of the propylene oxide is 3 to 5 times the amount of substance of phosphorus oxychloride.

[0053] Preferably, the catalyst is one or more of aluminum trichloride, titanium tetrachloride, tetrabutyl titanate, zinc chloride, magnesium chloride, iron chloride, and the corresponding ionic liquid catalysts.

[0054] Preferably, the reaction stage lasts for 0.2 - 5 min, and the post-treatment stage lasts for 0.3 - 5 min.

[0055] Preferably, the post-treatment stage includes continuously subjecting the reaction solution after reaction to vacuum removal of residual propylene oxide and low-boiling impurities, continuous washing, continuous liquid separation, and continuous drying and dehydration operations;

[0056] The continuous washing is as follows: First, water is added to fully mix and wash with the reaction solution after vacuum removal of residual propylene oxide and low-boiling impurities, which is an acid washing process. Then, alkali washing is carried out, and finally, water washing is performed with water.

[0057] Preferably, the water after acid washing is 10% - 100% of the mass of the phosphorus oxychloride.

[0058] Preferably, the water during the acid washing process is 5% - 100% of the mass of the phosphorus oxychloride.

[0059] Preferably, the flow rate of water during the acid washing process is 0.008 L / h - 3.29 L / h;

[0060] The flow rate of the alkali solution during the alkali washing is 0.01 L - 6.0 / h;

[0061] The flow rate of the water used for water washing after alkali washing is 0.1 - 2.5 L / h.

[0062] The present invention creatively conducts the reaction stage and the post-treatment stage as an integrated process continuously and without interruption. Raw materials continuously enter the reactor feed port, and commercially available standard TCPP finished products are continuously obtained at the reactor outlet, truly realizing the full continuous flow production of TCPP and achieving the rapid preparation of high-quality tris(1-chloro-2-propyl) phosphate (TCPP) finished products. Surprisingly, using the process of the present invention, TCPP finished products with stable acid value, zero content of aldehyde impurities, and zero content of metal cations corresponding to the catalyst, which could not be obtained by the prior art, are prepared. Other indicators are also superior to those of the prior art products. Moreover, the process generates less wastewater with low phosphorus content, which is beneficial to environmental protection and suitable for safe industrial production. The production process of the present invention is completed in an integrated continuous flow reactor, occupying a small area and greatly saving factory building land and costs.

[0063] Further, the post-treatment stage includes continuously subjecting the continuous reaction to vacuum removal of residual propylene oxide (PO) and low-boiling impurities, continuous washing, continuous liquid separation, and continuous drying and dehydration operations.

[0064] Further, the total time of the TCPP production process is 0.5 to 10 minutes, more preferably 2 to 8 minutes, and most preferably 4 to 6 minutes. The total time of the TCPP production process includes the total time of the reaction stage and the post-treatment stage, that is, the total time from when the raw materials phosphorus oxychloride and propylene oxide enter the reactor until the qualified TCPP finished product is obtained.

[0065] Further, the time (T1) of the reaction stage is 0.2 to 5 minutes, and the time of the post-treatment stage is preferably 0.3 to 5 minutes. Specifically, the time (T2) for continuously vacuum removing the remaining propylene oxide (PO) and low-boiling impurities is preferably 0.1 to 1 minute, the time (T3) for continuous washing and continuous liquid separation is preferably 0.1 to 2 minutes, and the time (T4) for continuous drying and dehydration is preferably 0.1 to 2 minutes.

[0066] In the present invention, the raw materials propylene oxide, phosphorus oxychloride, and catalyst are successively passed through an integrated continuous flow reactor to complete the two process stages of reaction and post-treatment, obtaining a TCPP finished product with excellent quality. In the fully continuous flow production process of TCPP described in the present invention, at any time during the production process, there is a sufficient amount of propylene oxide and phosphorus oxychloride, and there is no need for additional operations such as supplementary addition or dropping addition. Moreover, in the post-treatment process, each material is in sufficient quantity, which belongs to a brand-new production process. The prior art cannot achieve a one-time sufficient addition of raw materials and all require batch addition or dropping addition methods to achieve.

[0067] Further, the catalyst is a Lewis acid catalyst or a corresponding Lewis acid ionic liquid catalyst.

[0068] Further, the catalyst is selected from one or more of aluminum trichloride, titanium tetrachloride, tetrabutyl titanate, zinc chloride, magnesium chloride, iron chloride, and the corresponding ionic liquid catalysts.

[0069] Further, the catalyst dosage is 0.01% to 1% of the weight of POCl3, and its preferred dosage is 0.01% to 0.5%, more preferably 0.1% to 0.5%, and more preferably 0.2% to 0.4%. The specific dosage is determined according to different catalyst types and the actual reaction conditions (different flow rates, different temperatures, etc. need to be comprehensively matched). Further, the dosage of propylene oxide is 3.0 to 5.0 times the amount of substance of POCl3, preferably 3.0 to 4.0 times, more preferably 3.0 to 3.5 times, and more preferably 3.01 to 3.1 times.

[0070] Further, the temperature of the reaction stage is 0 to 200 °C, preferably 0 to 30 °C, more preferably 30 to 150 °C, more preferably 50 to 120 °C, more preferably 60 to 80 °C; more preferably, 100 to 200 °C; more preferably, 150 to 200 °C.

[0071] Further, the temperature in the post-treatment stage is 30 to 200 °C, preferably 30 to 50 °C, more preferably 50 to 180 °C, more preferably 60 to 150 °C, more preferably 150 to 200 °C, and even more preferably 100 to 200 °C.

[0072] Generally, the reaction temperature for the industrial production of TCPP is currently 40 to 90 °C. The main reason is that the current production method requires a certain reaction temperature to initiate, but too high a temperature will cause the reaction to get out of control, easily generate impurities and pose safety hazards. Using the fully continuous flow production process of the present invention, the raw materials can be initiated and reacted at a lower temperature, enabling the reaction to be initiated at 0 to 40 °C; it can also better control the reaction at a higher reaction temperature in the prior art, enabling the reaction to operate stably at 90 to 200 °C, avoiding the occurrence of side reactions and safety problems. In the current industrial post-treatment process, especially the washing process temperature is generally controlled at 75 to 95 °C, which further results in too long a washing time, reduced washing efficiency, and a decline in washing effect, resulting in a high acid value. When the temperature is higher, the washing water phase will boil, greatly reducing the washing effect and causing the decomposition of TCPP products during the washing process, reducing product quality and yield. Using the fully continuous flow production process of the present invention, washing can be carried out at a lower temperature to obtain a finished product with a low acid value and meet the standards, enabling the post-treatment operation of washing to be completed at 30 to 50 °C. At the same time, using the fully continuous flow production process of the present invention, the washing time is greatly shortened, enabling washing to be carried out at a higher temperature (150 to 200 °C) without causing the decomposition and loss of TCPP products during the washing process.

[0073] Further, propylene oxide (PO) can be fed in one stream or multiple streams.

[0074] Further, phosphorus oxychloride (POCl3) containing a catalyst can also be fed in one stream or multiple streams.

[0075] Further, after the reaction stage is completed, while continuously removing the residual PO in the reaction solution under vacuum, the low-boiling impurities generated during the reaction process can be removed together. This has a positive effect on improving the quality of the finished product.

[0076] Further, before adding alkali to the crude TCPP product after removing PO, water is first added and fully mixed with the crude product for washing, which is the pickling process, followed by alkali washing and finally water washing.

[0077] Further, the amount of water added in the pickling process is 5% to 100% of the mass of the POCl3 feed, preferably 10% to 80%, more preferably 20% to 50%.

[0078] Furthermore, the base used in the caustic washing is selected from water-soluble metal hydroxides, water-soluble quaternary ammonium hydroxides, and water-soluble tertiary amines. Alkali metal hydroxides or alkaline earth metal hydroxides are preferred, and sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, or lithium hydroxide are more preferred.

[0079] Furthermore, the mass concentration of the caustic solution is 0.1% to 40%, preferably 0.5% to 20%, and more preferably 1% to 8%.

[0080] Furthermore, the dosage of the caustic solution is 2% to 100% of the mass of the POCl3 feed, preferably 5% to 50%, and more preferably 10% to 30%.

[0081] Furthermore, the water consumption for the water washing after the caustic washing is 10% to 100% of the mass of the POCl3 feed, preferably 20% to 80%, and more preferably 40% to 60%.

[0082] In the prior art, in order to remove the acid-labile impurities in the crude TCPP product, most methods involve first adding an acid for washing and then performing subsequent operations such as caustic washing and water washing. The operation is complex and time-consuming. Moreover, if the TCPP product itself is under acidic conditions for too long, hydrolysis will occur, resulting in a decrease in yield. In the prior art for the post-treatment process of the crude TCPP product, acid washing and caustic washing are two independent and separate processes, which require two sets of equipment to achieve. The acid washing process requires the additional addition of acidic substances (strong acids, acids with high concentrations, hydrochloric acid, sulfuric acid, phosphoric acid aqueous solutions), and the contact time between the crude TCPP product and the acid is too long. The acid washing time ranges from half an hour to several hours. After acid washing, caustic washing is performed, and after caustic washing, water washing is performed to make the pH value of the TCPP product neutral. The caustic washing and water washing times also each require half an hour to several hours. Its disadvantages are as follows: Acid washing will cause the hydrolysis of TCPP, resulting in a decrease in yield; adding additional acid in acid washing increases the burden of caustic washing, increases production costs, and also increases the time and environmental pollution of post-treatment.

[0083] In the pickling process of the present invention, no additional acidic substances are required. Instead, through the seamless connection of the reaction stage and the post-treatment stage, the effect of the pickling process is achieved by pre-adding the water required for alkaline washing to the washing. The solution obtained by mixing the crude TCPP product prepared in the reaction stage with water is weakly acidic. Using the fully continuous flow production process of TCPP, the operation of pickling and removing impurities is completed in a weakly acidic environment, and the pickling time is significantly shortened. The duration of the pickling process is preferably 1 to 10 seconds, more preferably 2 to 6 seconds. It should be noted that different from the pickling time of half an hour to several hours in the prior art, the pickling time of the present invention is controlled within the range of seconds, which is much shorter than the prior art. Therefore, after the washing process of the present invention, the prepared TCPP finished product has higher quality and better stability, and no additional acidic substances need to be added, which not only ensures the yield, reduces the production cost, but also shortens the production time and improves the quality of the finished product. The fully continuous flow production process adopted by the present invention efficiently integrates and continuously performs the pickling, alkaline washing, and water washing processes, and can complete the pickling, alkaline washing, and water washing operations within a very short time (within 10 seconds). Under the condition of ensuring that the product does not decompose and has a high yield, a more pure and stable TCPP finished product is obtained. And under the condition of using the continuous flow production process of the present invention, the water required for alkaline washing is first added to the crude TCPP product to produce a weak acid environment, and then the TCPP finished product obtained after adding the alkaline solution according to the ratio does not turn sour, avoiding the sour finished product obtained by directly adding alkali for washing or adding acid first and then adding alkali.

[0084] Furthermore, the phosphorus content in the wastewater after alkaline washing and water washing in the prior art is above 2000 ppm. Due to the volatility of the production materials in the existing method, the phosphorus content in the wastewater of some production batches with low yields is even as high as 7000 - 8000 ppm or more, and the wastewater contains impurities generated during the synthesis process, so it cannot be directly recycled and reused, and needs to be treated by microorganisms or other methods before discharge to reduce the phosphorus content in the wastewater to below 8 ppm. Using the fully continuous flow production process of the present invention, because the reaction degree is high, and at the same time the side reactions and impurities are few, there are fewer phosphorus-containing raw materials, phosphorus-containing intermediates and other by-products that need to be removed in the crude product obtained by the reaction, resulting in a significant reduction in the phosphorus content in the aqueous phase after washing. After testing, the phosphorus content in the alkaline washing wastewater and water washing wastewater obtained by the fully continuous flow production process is 100 - 1000 ppm. Correspondingly, due to the better control of reaction impurities in the continuous flow production process, there are fewer impurities in the aqueous phase after washing, and the wastewater produced in the post-treatment can be recycled, greatly reducing the water consumption and wastewater generation. After calculation, without recycling, the water consumption in the alkaline washing process of the fully continuous flow production process of the present invention is 25% - 30% less than the current workshop consumption, and the water washing process of the present invention is 55% - 60% less than the current workshop, and the overall water consumption drops by 40 - 45%. Whether it is the aqueous phase after alkaline washing or the aqueous phase after water washing, it can be recycled after use to further control the cost.

[0085] The reaction process can be carried out under solvent-free conditions, or the addition of a solvent can be considered. The solvents selected are benzene, toluene, xylene, cyclohexane, methylcyclohexane, carbon tetrachloride, chloroform, dichloromethane, dimethyl carbonate, ethyl acetate, acetone, acetonitrile, etc. These solvents can be removed together with propylene oxide in the stage of removing propylene oxide after the reaction ends. Specifically, TCPP can also be selected as the solvent. The advantage of using TCPP as the solvent is that it does not need to be removed from the system after the reaction ends because it is the product itself. The way to add the solvent to the reaction system can be to feed the solvent alone into the reaction system. Further, the flow rate of the solvent is 0.1 - 2.5 L / h, preferably 0.3 - 2.0 L / h, more preferably 0.5 - 1.6 L / h; it can also be to mix the solvent with a certain raw material in a certain ratio first and then enter the reaction system. At this time, the flow rate should be the sum of the flow rates of the raw material and the solvent.

[0086] The flow rate of the phosphorus oxychloride (POCl3) solution containing the catalyst is 0.1 - 2 L / h, preferably 0.3 - 1.8 L / h, more preferably 0.5 - 1.5 L / h.

[0087] The flow rate of the reaction raw material propylene oxide (PO) is 0.2 - 6.0 L / h, preferably 0.6 - 4.5 L / h, more preferably 1.1 - 3.4 L / h.

[0088] Further, the flow rate of water in the pickling process is 0.008 L / h - 3.29 L / h, preferably 0.016 L / h - 1.645 L / h, more preferably 0.032 L / h - 1.645 L / h.

[0089] Further, the flow rate of water during the caustic washing is 0.1 - 3 L / h, preferably 0.2 - 2.0 L / h, more preferably 0.3 - 1.5 L / h.

[0090] Further, the flow rate of the caustic solution during the caustic washing is 0.01 - 6.0 L / h, preferably 0.1 - 3.0 L / h, more preferably 0.2 - 1.0 L / h.

[0091] Further, the flow rate of the water used for the water washing after the caustic washing is 0.1 - 2.5 L / h, 0.2 - 1.8 L / h, more preferably 0.4 - 1.5 L / h.

[0092] It should be noted that in actual production (including laboratory, pilot scale, and actual production processes), the reaction substrates, catalysts, etc. used have a mass concentration deviation of ±2 percentage points; the temperature in the temperature zone has a deviation of ±3 °C; the production time has a deviation of ±5 s.

[0093] Further, the integrated continuous flow reactor includes a reaction unit and a post-treatment unit. The raw materials, namely propylene oxide, phosphorus oxychloride, and catalyst, complete the reaction stage in the reaction unit and then obtain the TCPP finished product meeting the commercial standards through the post-treatment unit.

[0094] Further, the post-treatment unit is used to continuously and vacuum-remove the remaining propylene oxide (PO) and low-boiling impurities from the reaction solution, continuously wash and separate the liquid, and continuously dry and dehydrate.

[0095] Further, the continuous vacuum removal of the remaining propylene oxide (PO) and low-boiling impurities can be completed through a continuous distillation column. Further, the distillation temperature is preferably 50 - 200 °C, more preferably 80 - 150 °C, and even more preferably 90 - 120 °C.

[0096] Further, the reaction unit and the post-treatment unit respectively contain one or more functional units, which are optimized and matched by temperature zones and reactor modules or reactor module groups. By using the optimized matching of different temperature zones and reactor modules or reactor module groups and the synergistic effect between each section of reaction equipment, the total production process time of the finished product is shortened to within 10 minutes, or even shortened to within a few minutes, greatly improving the production process efficiency. Due to the continuous flow production process, the production time is short, and the total production process time is within 10 minutes. Multiple operation processes of the entire process can be carried out at a very high temperature without causing the decomposition and loss of the finished product.

[0097] Further, the reaction unit of the continuous flow production process contains at least one temperature zone. Preferably, the reaction unit includes 3 temperature zones: Temperature Zone 1, Temperature Zone 2, and Temperature Zone 3. The reaction raw materials POCl3 and PO enter Temperature Zone 1, Temperature Zone 2, and Temperature Zone 3 through a constant flow pump to complete processes such as mixing, reaction initiation, and reaction completion. Through the matching of reactor modules or reactor module groups in each temperature zone and the control of temperature, the heat generated by the reaction is removed or the required reaction heat is supplied, enabling the ring-opening addition reaction to be smoothly, controllably, and safely and efficiently completed within the reaction unit.

[0098] Further, the 3 temperature zones of the reaction unit can exist simultaneously to enable the functional unit to achieve different effects (such as reaction mixing, initiation, reaction, etc.), or can be used separately. Even if only one temperature zone is retained, the entire process of the reaction stage can still be continuously completed, and then the TCPP finished product meeting the quality requirements can be obtained through the post-treatment stage.

[0099] Further, the process temperature of Temperature Zone 1 is 0 - 200 °C, preferably 30 - 150 °C, and more preferably 40 - 100 °C.

[0100] The process temperature of Temperature Zone 2 is 30 - 150 °C, preferably 50 - 120 °C, and more preferably 60 - 80 °C.

[0101] The process temperature of temperature zone 3 is 30 to 200 °C, preferably 60 to 150 °C, more preferably 80 to 120 °C.

[0102] Further, pickling, caustic washing, and water washing operations are completed in the temperature zones of the post-treatment unit, and 3 temperature zones are used in cooperation. For example, the crude product obtained after vacuum treatment and water are fed into temperature zone 4 by a constant flow pump. After the crude product and water are fully contacted in temperature zone 4 to form a weakly acidic solution, acidic unstable impurities and metal cations can be removed after matching with an appropriate temperature. At the same time, an alkali solution with a suitable concentration and dosage enters temperature zone 5 under the action of a constant flow pump to make the solution obtained in temperature zone 4 become alkaline to complete the caustic washing operation. The solution after caustic washing completes oil-water separation through an oil-water separator. The oil phase enters temperature zone 6, and the water phase is discharged or recycled. The oil-water separator is a continuous oil-water separation device well-known to those skilled in the art. Similarly, when the oil phase enters temperature zone 6, the washing water enters temperature zone 6 under the action of a constant flow pump to fully contact with the oil phase to complete the water washing operation.

[0103] Further, the post-treatment unit of the integrated continuous flow reactor includes 3 temperature zones: temperature zone 4, temperature zone 5, and temperature zone 6.

[0104] Further, the process temperature of temperature zone 4 is preferably 30 to 200 °C, more preferably 50 to 180 °C, more preferably 60 to 150 °C.

[0105] Further, the process temperature of temperature zone 5 is preferably 30 to 200 °C, more preferably 50 to 180 °C, more preferably 60 to 150 °C.

[0106] Further, the process temperature of temperature zone 6 is preferably 30 to 200 °C, more preferably 50 to 180 °C, more preferably 60 to 150 °C.

[0107] Further, the product obtained after being treated in temperature zone 6 completes oil-water separation through an oil-water separator. The water phase is discharged from the reactor or recycled, and the oil phase enters a thin film evaporator or a molecular distillation evaporator for drying operation to obtain the final finished product.

[0108] Further, the preferred process temperature for thin film evaporation is 30 to 200 °C, more preferably 50 to 180 °C, more preferably 60 to 150 °C.

[0109] Further, the full continuous flow production process is carried out in an integrated continuous flow reactor comprising one or more functional units.

[0110] Furthermore, the integrated continuous flow reactor adopts a unitized structure. The reactor comprises at least one functional unit, each functional unit comprises at least one temperature zone, and each functional unit independently comprises one or more reactor modules or reactor module groups. Among them, the temperature zones of each functional unit are connected in series with each other, and one or more reactor modules or reactor module groups within each functional unit are connected in series or in parallel. Further, one or more functional units can be used to complete the continuous flow process, and the functional units can be connected in series or in parallel. The functional unit can be composed of one or more temperature zones, and each temperature zone can be matched with one or more reactor modules or reactor module groups.

[0111] Furthermore, a buffer (Buffer vessel) can be included between the functional units.

[0112] Furthermore, the number of feed inlets of the integrated continuous flow reactor is one or more, and the number of discharge outlets of the integrated continuous flow reactor is one or more.

[0113] Furthermore, the reactor module is optionally any reactor capable of implementing the integrated continuous flow process, and the reactor is selected from any one or more of a microreactor, a tandem loop reactor, and a tubular reactor.

[0114] Furthermore, the reactor can be one or more.

[0115] Furthermore, the material of the reactor module channel is single crystal silicon, special glass, ceramic, stainless steel or metal alloy coated with a corrosion-resistant coating, or polytetrafluoroethylene.

[0116] Furthermore, the reactor is composed of different functional units, and the functional units are matched with different temperature zones and different temperatures of the temperature zones, and at the same time are matched with different numbers of reactor modules or reactor module groups.

[0117] Furthermore, the reactor modules, the reactor module groups, and between the reactor modules and the reactor module groups are all connected in series or in parallel respectively.

[0118] The full continuous flow production process is carried out in an integrated continuous flow reactor comprising one or more functional units.

[0119] Furthermore, the integrated continuous flow reactor adopts a unitized structure. The reactor comprises one or more functional units, each functional unit contains at least one temperature zone, and each functional unit independently contains one or more reactor modules or reactor module groups. Among them, the temperature zones of each functional unit are connected in series with each other, and one or more reactor modules or reactor module groups within each functional unit are connected in series or in parallel.

[0120] Furthermore, the reactor can be of a unitized structure. It is necessary to design the organization mode and quantity of the modules, the temperature zones included in each functional unit, and it is also necessary to develop targeted process conditions and parameters, including the division and temperature setting of each temperature zone. The functional unit contains temperature zones and reactor modules or reactor module groups, enabling the above various factors to act synergistically, thus realizing this continuous flow process. The temperature of each temperature zone and the material flow rate can be further combined to match the usage process, obtaining a better usage effect.

[0121] Furthermore, one or more functional units can be used to complete the continuous flow process, and the functional units can be connected in series or in parallel. A functional unit can be composed of one or more temperature zones, and each temperature zone can be matched with one or more reactor modules or reactor module groups.

[0122] Furthermore, a buffer (Buffer vessel) can be included between the functional units. The buffer is a container with a certain volume, mainly used to buffer the pressure fluctuation of the system and balance the flow rate difference, making the system work more smoothly.

[0123] Furthermore, the number of feed inlets of the integrated continuous flow reactor is one or more, and the number of discharge outlets of the integrated continuous flow reactor is one or more.

[0124] Furthermore, the reactor module is optionally any reactor that can realize the integrated continuous flow process. The reactor is selected from any one or more of a microreactor, a tandem loop reactor, and a tubular reactor. The microreactor, also known as a microstructured reactor or a microchannel reactor, is a device in which a chemical reaction occurs in a limited area with a general lateral dimension of 1 mm or less. The most typical form of this limited area is a micro-sized channel. The tandem loop reactor is a reactor formed by connecting coil reactors in series with pipes, where the coil reactor is in the form of a coil made of a tubular reactor. The tubular reactor is a continuous operation reactor that emerged in the mid-20th century and is tubular in shape with a large length-to-diameter ratio. This reactor can be very long; it can be a single tube or multiple tubes in parallel; it can be an empty tube or a packed tube.

[0125] Furthermore, one or more of the reactors may be provided.

[0126] Furthermore, the material of the reactor module channels is single-crystalline silicon, special glass, ceramics, stainless steel or metal alloy coated with a corrosion-resistant coating, or polytetrafluoroethylene.

[0127] Furthermore, the reactors between the reactor modules, between the reactor module groups, and between the reactor module and the reactor module group are respectively in series or parallel.

[0128] Furthermore, the reactor is composed of different functional units, and the functional units are matched with different temperature zones and different temperatures in the temperature zones, and at the same time are matched with different numbers of reactor modules or reactor module groups.

[0129] Furthermore, each temperature zone is matched with the same or different numbers of reactor modules or reactor module groups, and different temperatures are matched for different reactor modules or reactor module groups. By matching different temperatures, different numbers, and types of reactor modules or reactor module groups for the temperature zones of the functional units, multiple different conditions can be formed for the functional units, enabling the functional units to have diversified functions, which makes the functional units more flexible during use and capable of achieving more process operations, such as reactions and post-treatments, etc. Furthermore, the functional units can achieve continuous flow production through series or parallel connection.

[0130] Furthermore, the integrated continuous flow reactor includes a reaction unit and a post-treatment unit. The raw materials propylene oxide, phosphorus oxychloride, and catalyst complete the reaction stage in the reaction unit and then obtain the TCPP finished product through the post-treatment unit.

[0131] Furthermore, the post-treatment unit is used to continuously and vacuum remove the remaining propylene oxide (PO) and low-boiling impurities from the reaction solution, continuously wash and separate the liquid, and continuously dry and dehydrate.

[0132] Furthermore, the equipment for continuously and vacuum removing the remaining propylene oxide (PO) and low-boiling impurities is a continuous distillation column. Furthermore, the temperature of the distillation is preferably 50 - 200 °C, more preferably 80 - 150 °C, and even more preferably 90 - 120 °C.

[0133] Furthermore, the reaction unit and the post-treatment unit each contain one or more functional units, which are optimally matched and combined by temperature zones and reactor modules or reactor module groups. By utilizing the optimal matching of different temperature zones and reactor modules or reactor module groups and the synergistic effect among various reaction equipment segments, the total production process time of the finished product is shortened to within 10 minutes, or even shortened to within a few minutes, greatly enhancing the efficiency of the production process. Due to the adoption of a continuous flow production process with a short production time and a total production process time within 10 minutes, multiple operating processes of the entire process can be carried out at a very high temperature without causing decomposition and loss of the finished product.

[0134] Furthermore, the three temperature zones of the reaction unit coexist simultaneously, enabling the functional unit to achieve different effects (such as reaction mixing, initiation, reaction, etc.).

[0135] Furthermore, the reaction unit of the integrated continuous flow reactor includes three temperature zones: Temperature Zone 1, Temperature Zone 2, and Temperature Zone 3. The reaction raw materials POCl3 and PO enter Temperature Zone 1, Temperature Zone 2, and Temperature Zone 3 through a constant flow pump to complete processes such as mixing, reaction initiation, and reaction completion. Through the matching of reactor modules or reactor module groups in each temperature zone and the control of temperature, the heat generated by the reaction is removed or the required reaction heat is supplied, enabling the ring-opening addition reaction to be smoothly, controllably, and safely and efficiently completed within the reaction unit.

[0136] Furthermore, pickling, alkali washing, and water washing operations are completed in the temperature zones of the post-treatment unit, and three temperature zones are used in cooperation. For example, the crude product obtained after vacuum treatment and water are flowed into Temperature Zone 4 through a constant flow pump. After the crude product and water are fully contacted in Temperature Zone 4 to form a weakly acidic solution, acidic unstable impurities and metal cations can be removed after matching with an appropriate temperature. Meanwhile, an alkali solution with a suitable concentration and dosage enters Temperature Zone 5 under the action of a constant flow pump, turning the solution obtained in Temperature Zone 4 into an alkaline state to complete the alkali washing operation. The solution after alkali washing undergoes oil-water separation through an oil-water separator. The oil phase enters Temperature Zone 6, and the water phase is discharged or recycled. The oil-water separator is a well-known continuous oil-water separation device in the industry. Similarly, when the oil phase enters Temperature Zone 6, the washing water enters Temperature Zone 6 under the action of a constant flow pump to fully contact the oil phase to complete the water washing operation.

[0137] Furthermore, the post-treatment unit of the integrated continuous flow reactor includes three temperature zones: Temperature Zone 4, Temperature Zone 5, and Temperature Zone 6.

[0138] Furthermore, the preferred process temperature for Temperature Zone 4 is 30 - 200 °C, more preferably 50 - 180 °C, and even more preferably 60 - 150 °C.

[0139] Furthermore, the preferred process temperature for Temperature Zone 5 is 30 - 200 °C, more preferably 50 - 180 °C, and even more preferably 60 - 150 °C.

[0140] Further, the preferred process temperature in temperature zone 6 is 30 - 200°C, more preferably 50 - 180°C, and even more preferably 60 - 150°C.

[0141] Further, the product obtained after treatment in temperature zone 6 undergoes oil-water separation by an oil-water separator. The aqueous phase is discharged from the reactor or recycled, and the oil phase enters a thin-film evaporator or a molecular distillation evaporator for drying operation to obtain the final product.

[0142] Further, the preferred process temperature for thin-film evaporation is 30 - 200°C, more preferably 50 - 180°C, and even more preferably 60 - 150°C.

[0143] Further, in order to enable the continuous flow reactor to be applicable to more continuous flow production process conditions, the reactor is equipped with more functional units. Correspondingly, there will also be more temperature zones. The actual number of temperature zones selected will be correspondingly matched according to different reaction conditions. When the temperatures of consecutive temperature zones are the same, they can be regarded as the same temperature zone. For example, when the temperatures of temperature zone 4 and temperature zone 5 are the same, the two can be integrated into a new temperature zone 4. Then, at this time, the integrated reactor actually has 5 temperature zones: temperature zone 1, temperature zone 2, temperature zone 3, new temperature zone 4 (temperature zone 4 + temperature zone 5), and temperature zone 5. The same applies to others.

[0144] Further, due to the fast and efficient production characteristics of the continuous flow production process, on the premise of ensuring product stability and yield, the entire production process can be carried out at higher temperature conditions than the current process. Under high temperature conditions, obviously, the higher the temperature, the faster the reaction, which also promotes the production efficiency of the continuous flow production process. The two influence each other.

[0145] Furthermore, when producing TCPP using an integrated continuous flow reactor, it is necessary to strictly match the feed rate, material ratio, catalyst dosage, the number of reactor modules or reactor module groups, and the combination between the reactor modules or reactor module groups and different temperature zones. For example, when a low-content catalyst is used under high flow rate conditions, the number of reactor modules or reactor module groups needs to be correspondingly increased. However, when the temperature of the temperature zone is enhanced to a sufficiently high level, the number of module groups can be reduced. Correspondingly, when a high catalyst dosage is used, it can be carried out at a higher flow rate, with fewer reactor modules or reactor module groups, and a relatively lower temperature. TCPP will decompose under long-term high-temperature conditions, which is well-known to those skilled in the art. The matching of the number of temperature zone modules, temperature, and flow rate needs to be very appropriate so that the residence time of TCPP in the high-temperature section is only a few minutes or even a few seconds, minimizing the loss of the product caused by decomposition to the greatest extent. The matching between various process parameters and equipment needs to be quite strict, but the overall matching conditions are quite flexible. Only by matching appropriate process parameters and equipment conditions can continuous flow production be achieved through the integrated continuous flow reactor, maximizing the use efficiency of the integrated continuous flow reactor while saving production time, reducing wastewater, improving product quality, and enhancing the stability of the finished product. Simply using the modules or module groups of the reactor cannot achieve the purpose and effect of the present invention.

[0146] Furthermore, the reactor modules are combined with multiple separate temperature zones, and the temperatures during the production process can be the same or different, enabling the continuous flow reactor to be applicable to more feed flow rates, catalyst dosages, caustic washing, and water washing conditions, forming independent functional units. These functional units can be connected in series or in parallel in the reactor. Through such matching, the continuous flow production process becomes more flexible and has stronger applicability to different production conditions.

[0147] The comparison between the present invention and the prior art has the following beneficial effects:

[0148] 1. The TCPP product obtained by the fully continuous flow production process of TCPP in the present invention has a stable acid value and the content of aldehyde impurities is 0. The acid value (mg KOH / g) ≤ 0.1, the moisture content (wt.%) ≤ 0.1, the color (APHA) ≤ 50, and the viscosity (25°C, mPa·s) is 50 - 80. The TCPP product obtained by the present invention can also be free of the metal cations corresponding to the catalyst, significantly improving the quality of the TCPP product.

[0149] 2. The present invention realizes the fully continuous flow production of TCPP for the first time. Creatively, the reaction stage and the post-treatment stage are carried out continuously and uninterruptedly as an integral process. Raw materials continuously enter the reactor feed port, and TCPP finished products meeting the commercial standards are continuously obtained at the reactor outlet, realizing the rapid preparation of high-quality tris(1-chloro-2-propyl) phosphate (TCPP) finished products. Through the integrated reaction process, the fully continuous flow production process for TCPP preparation is realized. Compared with the prior art, the reaction time of the present invention is greatly shortened, and the production efficiency is significantly improved. The production process of the present invention is completely different from the prior art process. The reaction unit and the post-treatment unit are integrated into a complete production process, and finished products meeting the commercial industrial product standards can be directly obtained within a short time (within 10 minutes), realizing high-quality and high-efficiency production.

[0150] 3. The production process of the present invention is safe and efficient. The TCPP finished products obtained have very high quality and better stability, and there is no acid reflux after long-term storage.

[0151] 4. The present invention can significantly reduce the water consumption in post-treatment, that is, reduce the generation of wastewater, and the phosphorus content in the wastewater also decreases significantly, reducing the cost of wastewater treatment and making the production of TCPP more economical and environmentally friendly.

[0152] 5. The safety of the production process of the present invention has been greatly improved. Due to the relatively small liquid holdup and excellent heat transfer characteristics of the continuous flow reactor, combined with the short reaction time (within 10 minutes), the process is safer. The liquid holdup of the reactor mentioned herein refers to the total volume of the reaction materials existing in the reactor at any moment when the operation reaches a steady state. BRIEF DESCRIPTION OF THE DRAWINGS

[0153] Figure 1 Process diagram of the continuous flow production process of the present invention;

[0154] Figure 2 Schematic diagram of the integrated continuous flow reactor of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0155] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content of the present invention, those of ordinary skill in the art can make various changes or modifications to the present invention, and these equivalent or corresponding forms also fall within the scope defined by the appended claims of this application.

[0156] The following abbreviations are used in the examples:

[0157] POCl3: phosphorus oxychloride; PO: propylene oxide; AlCl3: aluminum chloride; TiCl4: titanium tetrachloride; ZnCl2: zinc chloride; MgCl2: magnesium chloride; FeCl3: iron(III) chloride; NaOH: sodium hydroxide; KOH: potassium hydroxide; Na2CO3: sodium carbonate; NaHCO3: sodium bicarbonate; K2CO3: potassium carbonate; KHCO3: potassium bicarbonate.

[0158] The concentrations in the embodiments of the present invention are all mass concentrations. It should be noted that in actual production (including laboratories, pilot plants, and actual production processes), the reaction substrates and catalysts used have a mass concentration deviation of ±2 percentage points; the temperature in the temperature zone has a deviation of ±3 °C; the production time has a deviation of ±5 s. As Figure 1 and Figure 2 shown, the raw material 1 containing the catalyst (phosphorus oxychloride containing the catalyst), raw material 2 (propylene oxide), material 1 (alkali washing water), material 2 (alkali solution), and material 3 (water washing water) are successively fed into the integrated continuous flow reactor by a constant flow pump and sequentially enter temperature zones 1 to 3, and the reaction is complete; the reaction liquid flowing out of temperature zone 3 enters the vacuum buffer tank to remove the residual PO, and then continuously enters temperature zones 4, 5, and 6 for post-treatment. The processed product is subjected to thin film dehydration operation, and finally a high-quality finished product is obtained. Among them, the feeding rate 1 represents the feeding rate of raw material 1, the feeding rate 2 represents the feeding rate of raw material 2, the feeding rate 3 represents the feeding rate of material 1, the feeding rate 4 represents the feeding rate of material 2, and the feeding rate 5 represents the feeding rate of material 3. Among them, the alkali washing water refers to the water added to the reactor before adding the alkali solution to the crude product; the water washing water refers to the water added to the reactor after the alkali washing process is completed.

[0159] Among them, T1 represents the time of the reaction stage, T2 represents the time for vacuum removal of the remaining propylene oxide (PO) impurities, T3 represents the time for continuous washing and continuous liquid separation, and T4 represents the time for continuous drying and dehydration.

[0160] Detection of aldehyde substances: The content of aldehyde impurities is determined by the external standard method of gas chromatography. Taking the detection of 2-methyl-2-pentenal as an example, the specific detection method is described as follows:

[0161] Drawing a standard curve: Accurately weigh a certain mass of 2-methyl-2-pentenal standard product, use anhydrous acetone as a solvent, and prepare several standard solutions with contents between 0.02 ppm and 0.2 ppm (not less than 3 samples). The corresponding data of different contents and peak areas are obtained by gas chromatography under certain conditions, and the standard curve is drawn:

[0162] Y = k·X + b.

[0163] In the above formula, Y—the content of aldehyde in the sample, ppm; k—the slope of the standard curve; X—the peak area; b—the intercept of the standard curve.

[0164] Sample determination: Accurately weigh 0.1000 g of the TCPP sample, add it to 10 ml of anhydrous acetone, shake until completely dissolved, and perform injection analysis. Substitute the peak area data into the standard curve formula to obtain the aldehyde content of the injected TCPP. The actual aldehyde content in TCPP is 100·Y (ppm).

[0165] The so-called non-acid-reflux means that the acid value of the TCPP finished product does not change. Specifically, the acid value (acid value) of the TCPP finished product remains unchanged during storage, transportation, or use by downstream users. The acid value is determined by the method in ASTM D974-2012. The specific operation is as follows:

[0166] Weigh about 10 - 15 g of the test sample, accurately weigh it, and place it in a 250 ml conical flask. Add 30 ml of anhydrous ethanol until the test sample is completely dissolved, add 0.5 ml of phenolphthalein indicator, and shake until colorless, uniform, and transparent. Titrate with a KOH standard solution until a faint pink color appears and remains for half a minute without fading, which is the titration end point.

[0167] Perform a blank test in the same way without adding the test sample.

[0168] The acid value is calculated as follows:

[0169] X = (V1 - V2)·C / m

[0170] In the above formula, X—the acid value of the test sample, mg KOH / g; V1—the volume of the KOH standard solution used in the titration of the test sample, mL; V2—the volume of the KOH standard solution used in the blank titration, mL; C—the concentration of the KOH standard solution, g / L; m—the mass of the test sample, g.

[0171] The so-called non-acid-reflux means that the acid value of the TCPP finished product does not change. Specifically, the acid value (acid value) of the TCPP finished product remains unchanged during storage, transportation, or use by downstream users. The acid value is determined by the method in ASTM D974-2012. The specific operation is as follows:

[0172] Weigh about 10 - 15 g of the test sample, accurately weigh it, and place it in a 250 ml conical flask. Add 30 ml of anhydrous ethanol until the test sample is completely dissolved, add 0.5 ml of phenolphthalein indicator, and shake until colorless, uniform, and transparent. Titrate with a KOH standard solution until a faint pink color appears and remains for half a minute without fading, which is the titration end point.

[0173] Perform a blank test in the same way without adding the test sample.

[0174] The acid value is calculated as follows:

[0175] X = (V1 - V2)·C / m

[0176] In the above formula, X—the acid value of the sample, mg KOH / g;

[0177] V1—the volume of the KOH standard solution used in the titration of the sample, mL; V2—the volume of the KOH standard solution used in the blank titration, mL; C—the concentration of the KOH standard solution, g / L; m—the mass of the sample, g.

[0178] Furthermore, in order to simply and quickly detect whether the finished product is acid-reversed and the degree of acid reversal, it can be characterized and reflected by using the aging test method. The specific method is as follows: Take 60 g of TCPP sample into an aging bottle with a volume of 60 ml, seal it well and put it into an oven at a constant temperature of 100 °C for 3 h, and compare the change in acid value before and after. If the acid value does not change, it means there is no acid reversal.

[0179] The residue of the metal cation corresponding to the catalyst is detected by an ICP-OES 7000DV instrument. The specific method is as follows:

[0180] Plot the working curve: Accurately weigh the standard substance of the metal element to be measured, and use a certain concentration of HNO3 to prepare several standard solutions with a content between 1 ppm and 100 ppm respectively; prepare a blank solution with the same acidity. Obtain the spectral absorption intensity data of the metal element standard solutions with different concentrations through instrumental analysis, and plot the working curve:

[0181] I = A·C

[0182] In the above formula, I—the spectral absorption intensity of the metal element;

[0183] A—the correlation coefficient; C—the concentration of the metal element.

[0184] Sample treatment and determination: Accurately weigh a certain mass of TCPP sample, and use a muffle furnace to ash it until the organic components are completely decomposed; dissolve the ash with a certain concentration of HNO3, transfer the solution after deacidification and make it up to the mark with a 100 ml volumetric flask. Obtain the spectral absorption intensity I of the element through instrumental detection and analysis, substitute it into the working curve to obtain the concentration C of the metal element in the sample after volume determination, and then calculate the content of the metal cation in it according to the mass of the TCPP sample weighed.

[0185] It can be seen from the examples that the integrated continuous flow process described in the present invention has obvious progress in the total process time, that is, it is shortened from more than 10 hours of the existing process to less than 10 minutes. At the same time, it can be seen from Examples 11 and 12 that the yield does not change after scale-up, and the production time does not increase significantly, indicating that there is no scale-up effect in the present invention.

[0186] Examples:

[0187]

[0188]

[0189] Comparative Example 1: An example in which the crude TCPP product is prepared by a continuous flow production process and the post-treatment is carried out by an intermittent industrial method

[0190] Under the production conditions of Example 5, 500 kg of the crude TCPP product was directly taken out from the integrated continuous flow reactor without using a reactor for post-treatment. The crude product was transferred to a 2000-liter stirred reactor, and then 17 kg of 30% NaOH aqueous solution and 500 kg of water were used for alkali washing at 75°C for 2 hours. After standing for 1 hour for stratification, it was washed with 500 kg of water for 2 hours, and then stood for hours. The dehydration operation was completed by thin film evaporation at 110°C. The acid value of the finished product was 0.03 mgKOH / g, and the acid value after aging was 0.05 mgKOH / g. The content of 2-methylenepentanal was 0.6 ppm.

[0191] Comparative Example 2: An example in which the crude TCPP product is prepared by an intermittent industrial method and the post-treatment is carried out by a continuous flow method

[0192] 500 kg of the currently industrially produced crude TCPP product was taken and the post-treatment operation was carried out using the integrated continuous flow reactor of the present invention. The flow rate of the crude product was 80 L / h, the flow rate of Material 1 was 25 L / h, Material 2 was 8% sodium hydroxide aqueous solution, the flow rate of Material 2 was 10.5 L / h, and the flow rate of Material 3 was 31.6 L / h. The temperature of the material flowing through the reactor was 130°C. After dehydration, the finished product was taken for analysis: the acid value of the finished product was 0.01 mgKOH / g, and the acid value after aging was 0.03 mgKOH / g. The content of 2-methylenepentanal was 33 ppm.

[0193] Comparative Example 3: The current industrial batch kettle TCPP production process

[0194] 3000 kg of phosphorus oxychloride and 9 kg of catalyst aluminum trichloride were put into an 8-cubic kettle, and the temperature was raised to 60°C under stirring, and then 3400 kg of cyclopropane was added dropwise for 5 hours, and then kept warm between 60 and 70°C for 5 hours. After the reaction was completed, PO was pulled under vacuum for about 30 min. Subsequently, 100 kg of 30% NaOH and 3000 kg of water were used for alkali washing at 75°C for 2 hours. After standing for 1 hour for stratification, it was washed with 3000 kg of water for 2 hours, and then stood for hours. The dehydration operation was completed by thin film evaporation at 110°C. The acid value of the finished product was 0.02 mgKOH / g, and the acid value after aging was 0.06 mgKOH / g. The content of 2-methylenepentanal was 15 ppm.

[0195] The above comparative examples illustrate that when only the continuous flow reaction is used, but the continuous flow post-treatment is not used, acid reflux still occurs in the obtained finished product; correspondingly, when the continuous flow reaction is not used, but only the continuous flow is used for post-treatment, the obtained finished product still has characteristics such as acid reflux and containing aldehyde impurities.

[0196] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. Other embodiments can also be obtained according to these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A fully continuous flow production method for finished tris(1-chloro-2-propyl) phosphate, characterized in that, The described production method is carried out in an integrated continuous flow reactor. The production method includes a reaction stage and a post-treatment stage, and the reaction stage and the post-treatment stage are carried out continuously and without interruption. Propylene oxide, phosphorus oxychloride solution containing a catalyst, an alkali solution, and water are continuously added to the feed inlet of the integrated continuous flow reactor, and tris(1-chloro-2-propyl) phosphate finished product is continuously obtained at the outlet of the integrated continuous flow reactor. The described integrated continuous flow reactor includes a reaction unit and a post-treatment unit; The reaction unit and the post-treatment unit respectively include multiple functional units. The functional unit includes a temperature zone and a reactor module or a group of reactor modules. Each functional unit includes at least one temperature zone. Each functional unit independently includes one or more reactor modules or a group of reactor modules. Among them, the temperature zones of the functional unit are connected in series with each other, and one or more reactor modules or a group of reactor modules in each functional unit are connected in series or in parallel. The reaction unit includes 3 temperature zones: temperature zone 1, temperature zone 2, and temperature zone 3; The process temperature of the temperature zone 1 is 0 - 200 °C; The process temperature of the temperature zone 2 is 30 - 150 °C; The process temperature of the temperature zone 3 is 30 - 200 °C; The flow rate of the phosphorus oxychloride solution containing a catalyst is 0.1 - 2 L / h; The flow rate of the propylene oxide is 0.2 - 6.0 L / h; The post-treatment unit includes 3 temperature zones: temperature zone 4, temperature zone 5, and temperature zone 6; The process temperature of the temperature zone 4 is 30 - 200 °C; The process temperature of the temperature zone 5 is 30 - 200 °C; The process temperature of the temperature zone 6 is 30 - 200 °C; The dosage of the catalyst is 0.01% - 1% of the mass of phosphorus oxychloride; The time of the reaction stage is 0.2 - 5 min, and the time of the post-treatment stage is 0.3 - 5 min; The described post-treatment stage includes continuously vacuum removing the remaining propylene oxide and low-boiling impurities from the reaction solution after the reaction, continuous washing, continuous liquid separation, and continuous drying and dehydration operations; The continuous washing is as follows: first, water is added to fully mix and wash with the reaction solution after vacuum removing the remaining propylene oxide and low-boiling impurities. This is an acid washing process, followed by alkali washing, and finally water washing.

2. The all-continuous flow production method according to claim 1, characterized in that, The catalyst is one or more of aluminum trichloride, titanium tetrachloride, tetrabutyl titanate, zinc chloride, magnesium chloride, and iron chloride.

Images