A method and apparatus for continuously producing dichloro pentaerythritol diphosphite

Abstract

The application provides a method for continuously preparing dichloro pentaerythritol diphosphite, relates to the technical field of chemical equipment, and comprises the following steps: step one, mixing pentaerythritol with an organic solvent to obtain a pentaerythritol suspension; step two, continuously performing esterification reaction on the pentaerythritol suspension and phosphorus trichloride in a scraped film reactor in one stage or multiple stages in series, discharging the generated HCl gas from the upper part of each scraped film reactor, and gradually flowing the reaction liquid discharged from the bottom of the scraped film reactor in multiple stages in series into the scraped film reactor in the next stage until the dichloro pentaerythritol diphosphite product solution is discharged from the bottom of the scraped film reactor, and the temperature of the esterification reaction is 30-100 DEG C. The application further provides a device for continuously preparing dichloro pentaerythritol diphosphite; and the scheme provided by the application has high yield, low energy consumption, and can continuously synthesize dichloro pentaerythritol diphosphite.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical equipment, in particular to a method and device for continuously preparing dichloro pentaerythritol diphosphite. BACKGROUND

[0002] Dichloro pentaerythritol diphosphite is a key intermediate for synthesizing phosphite antioxidants 618, 626, PEP-36, etc.

[0003] Dichloro pentaerythritol diphosphite is synthesized by the reaction of phosphorus trichloride and pentaerythritol, and the reaction equation is as follows:

[0004]

[0005] A large amount of hydrogen chloride is generated in the reaction process, and the discharge rate and residual amount of hydrogen chloride gas affect the conversion rate of the product.

[0006] There are generally two categories of methods for preparing dichloro pentaerythritol diphosphite: one category is catalytic reaction, such as European Patent EP0113994 using phosphoric acid ester as a catalyst for the direct reaction of phosphorus trichloride and pentaerythritol at a temperature of 90-110℃. Japanese Patent JP5059074 uses methyl formamide as a catalyst, and phosphorus trichloride is reacted with pentaerythritol in a toluene solvent with an excess of 20%. The other category is non-catalytic reaction, such as US Patent US3210398, US3192243, which uses chloroform as a solvent, and phosphorus trichloride is added to the chloroform suspension of pentaerythritol, and the reaction is carried out for 24-48 hours at room temperature. Czech Patent CS190732 uses toluene as a solvent at room temperature, and dry air or inert gas (such as nitrogen) is blown during the reaction process.

[0007] Chinese Patent CN1069645C slowly adds pentaerythritol to a phosphorus trichloride toluene solution system, and reacts for 5-10h at 40-60℃ under a vacuum degree of 5-30mmHg to prepare dichloro pentaerythritol diphosphite.

[0008] Chinese Patent CN102020677A drops phosphorus trichloride into a halogenated hydrocarbon pentaerythritol suspension at 0-5℃, and then heats to 35-160℃ to react for 1-12h to prepare dichloro pentaerythritol diphosphite. The low-temperature dropping in the early stage increases energy consumption and is not conducive to the discharge of generated hydrogen chloride gas.

[0009] Chinese patent CN108047273A adds phosphorus trichloride to a system of pentaerythritol, organic solvent and organic weak base at 15-20℃, undergoes two-stage heating reaction at 30-40℃ and 110-115℃, and extracts generated hydrogen chloride gas at 110-115℃ under vacuum to prepare dichloro pentaerythritol diphosphite. Its early stage adopts low-temperature dropwise addition, which increases energy consumption and is not conducive to the discharge of generated hydrogen chloride gas; the adoption of stage heating leads to increased side reactions and decreased yield.

[0010] The prior art all adopts a kettle type batch process, which has a long reaction time and low equipment generation efficiency; the kettle type reaction is difficult to quickly and completely discharge hydrogen chloride gas, in order to improve and ensure the product conversion rate, it adopts the mode of exhausting dry air or nitrogen, complicated stage heating, vacuum extraction and discharge, etc. to discharge as much generated hydrogen chloride as possible, which brings problems such as increased waste gas volume, increased side reactions, increased energy consumption, etc.

[0011] Since pentaerythritol is insoluble in toluene, halogenated hydrocarbon and other solvents, its reaction with phosphorus trichloride is a solid-liquid synthesis reaction to generate gas-liquid products, which has problems such as reactor blockage or solid material accumulation, and difficulty in timely discharging generated hydrogen chloride gas, affecting the reaction and causing increased side reactions, etc. in the development of a continuous process, and the development of a continuous process is difficult. Data query also shows that there is no report on the continuous synthesis of dichloro pentaerythritol diphosphite. SUMMARY

[0012] The purpose of the present application is to provide a method and device for continuously preparing dichloro pentaerythritol diphosphite, in order to solve the problems existing in the prior art, with high yield, low energy consumption and continuous synthesis of dichloro pentaerythritol diphosphite.

[0013] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0014] The present application provides a method for continuously preparing dichloro pentaerythritol diphosphite, comprising the following steps:

[0015] Step one, mixing pentaerythritol and an organic solvent to obtain a pentaerythritol suspension;

[0016] Step two, continuously esterifying the pentaerythritol suspension and phosphorus trichloride in a scraped film reactor in series, discharging generated HCl gas from the upper part of each scraped film reactor, and gradually discharging reaction liquid from the bottom of the scraped film reactor into the next scraped film reactor until dichloro pentaerythritol diphosphite product solution is discharged from the bottom of the scraped film reactor, and the temperature of the esterification reaction is 30-100℃.

[0017] Preferably, the molar ratio of pentaerythritol to phosphorus trichloride is 1:2-3.

[0018] Preferably, in step one, the organic solvent can be one or more of toluene, xylene, mesitylene, 1,2-dichloropropane, 1,3-dichloropropane, 1,2,3-trichloropropane.

[0019] Preferably, in step one, the pentaerythritol suspension contains added catalyst, and the molar ratio of pentaerythritol to catalyst is 1.0:0.01-0.50.

[0020] In the multi-stage scraped-film reactor in series, the catalyst is added to the inlet of each scraped-film reactor or to the inlet of some of the scraped-film reactors in series.

[0021] Preferably, the catalyst is an organic amine catalyst, which can be one or more of triethylamine, N,N-dimethyl aniline, N,N-dimethyl n-butylamine, N-methyl formamide, N,N-dimethyl cyclohexylamine, N,N-diisopropyl ethylamine, 4-dimethylamino pyridine, pyridine.

[0022] Preferably, in step two, the pentaerythritol suspension and phosphorus trichloride are pre-mixed by a mixer before entering the scraped-film reactor for reaction.

[0023] Preferably, in step two, the pentaerythritol suspension or the phosphorus trichloride raw material or the mixture of the pentaerythritol suspension and phosphorus trichloride is preheated to 30-60°C before entering the scraped-film reactor for reaction.

[0024] In the multi-stage scraped-film reactor in series, the reaction temperature in the first-stage scraped-film reactor is 30-80°C, the reaction temperature in the second-stage scraped-film reactor is 40-90°C, and the reaction temperature in the third-stage and subsequent scraped-film reactors is 40-100°C.

[0025] In the multi-stage scraped-film reactor in series, the phosphorus trichloride is divided into multiple streams and enters each scraped-film reactor or some of the scraped-film reactors in series for reaction.

[0026] The phosphorus trichloride entering each scraped-film reactor is mixed with the pentaerythritol suspension or the material discharged from the previous scraped-film reactor by a mixer before entering the corresponding scraped-film reactor.

[0027] The reaction pressure in the scraped-film reactor is micro-negative pressure, normal pressure or micro-positive pressure.

[0028] The HCl gas discharged from each scraped-film reactor is condensed by a condenser and subjected to gas-liquid separation and other recovery processes to recover the solvent and reactants entrained in the gas phase and return to the corresponding scraped-film reactor.

[0029] The multi-stage series-connected scraped-film reactor has 2-15 stages in series.

[0030] Preferably, the dichloro pentaerythritol diphosphite solution prepared by the scraped-film reactor is returned to the scraped-film reactor inlet to mix with the incoming pentaerythritol suspension and phosphorus trichloride for cyclic reaction until the desired conversion rate is reached.

[0031] The application also provides a device for continuously preparing dichloro pentaerythritol diphosphite, comprising a pentaerythritol suspension preparation kettle, a phosphorus trichloride storage tank, a premixer, a scraped-film reactor with one or more stages in series, and a hydrogen chloride tail gas absorption system; the pentaerythritol suspension preparation kettle and the phosphorus trichloride storage tank are both in communication with the inlet of the premixer, the outlet of the premixer is connected to the inlet of the first-stage scraped-film reactor, the gas phase outlet of the scraped-film reactor is connected to the gas inlet of the hydrogen chloride tail gas absorption system;

[0032] When only one stage of the scraped-film reactor is provided, the liquid phase outlet at the bottom of the scraped-film reactor is the outlet for the prepared dichloro pentaerythritol diphosphite product solution;

[0033] When a plurality of stages of the scraped-film reactor are provided in series, the liquid phase outlet at the bottom of the front-stage reactor is connected to the inlet of the rear-stage scraped-film reactor; the liquid phase outlet at the bottom of the last-stage scraped-film reactor is the outlet for the prepared dichloro pentaerythritol diphosphite product solution.

[0034] Preferably, the scraped-film reactor is internally provided with a liquid distribution device, and the inlet of the scraped-film reactor is connected to the internal liquid distribution device;

[0035] The scraped-film reactor is internally provided with a defoaming device, and the released hydrogen chloride gas is discharged from the gas phase outlet after passing through the defoaming device;

[0036] Each stage of the scraped-film reactor is correspondingly provided with a condenser and a gas-liquid separator, and the gas phase outlet of the scraped-film reactor is sequentially connected to the condenser and the gas-liquid separator, and then connected to the hydrogen chloride tail gas absorption system; the liquid phase outlet of the gas-liquid separator is connected to the condensate inlet of the corresponding scraped-film reactor;

[0037] The inlet of the premixer can be connected to the outlet of a first preheater and / or the outlet of a pentaerythritol suspension feed pump through a first preheater, the inlet of the pentaerythritol suspension feed pump is connected to the outlet of the pentaerythritol suspension preparation kettle, and the inlet of the phosphorus trichloride feed pump is connected to the outlet of the phosphorus trichloride storage tank;

[0038] The outlet of the premixer is connected to the inlet of the scraped-film reactor through a second preheater;

[0039] The pentaerythritol suspension preparation kettle is provided with a heating jacket;

[0040] When the plurality of the scraped-film reactors are arranged in series, the scraped-film reactor of a previous stage is connected with the scraped-film reactor of a next stage through a mixer, and the outlet of the phosphorus trichloride feeding pump is connected with the inlet of the mixer;

[0041] Further comprising a catalyst storage tank, the outlet of the catalyst storage tank is communicated with a catalyst feeding pump, and the catalyst feeding pump can pump catalyst to the pentaerythritol suspension preparation kettle and each of the scraped-film reactors or some of the scraped-film reactors.

[0042] The present application has the following technical effects relative to the prior art:

[0043] 1) The reaction of solid-liquid synthesis of pentaerythritol and phosphorus trichloride in a solvent to generate a gas-liquid product is carried out in the scraped-film reactor, the reaction proceeds rapidly, because the scraped-film reactor can mix the materials violently, increasing the contact of the reactants; the scraped-film reactor is very suitable for the solid-liquid reaction system, and there are no problems such as plugging and solid accumulation; the material liquid film layer is very thin, the heat transfer area is large and the heat transfer is fast, which is conducive to precise temperature control; the generated hydrogen chloride can be quickly separated from the film layer, so that the reaction in the material liquid film layer is pushed to the right.

[0044] 2) The material liquid in the scraped-film reactor flows from top to bottom using gravity, which can very well control back mixing and reduce the occurrence of side reactions; the flow direction of the material liquid film layer is opposite to the discharge direction of the hydrogen chloride gas, the closer to the end point of the material, the lower the concentration of hydrogen chloride in the gas-liquid two phases, which maximizes the avoidance of the influence of hydrogen chloride on the reaction, is conducive to accelerating the reaction speed, controlling the occurrence of side reactions, and obtaining high yield of products.

[0045] 3) The multi-stage series reactor can be heated by gradient, to meet the precise control requirements of reaction temperature at different stages.

[0046] 4) The present application does not need a large vacuum pumping system, nor does it need to introduce dry air or nitrogen to assist the discharge of hydrogen chloride gas, which reduces the amount of waste gas emissions, and the reaction can be well completed under micro-negative pressure, normal pressure or micro-positive pressure, achieving good energy saving and environmental protection effects.

[0047] 5) The production process of the present application is continuous, the equipment utilization rate is high, the production capacity is large, the automation operation is easy to realize, the process parameters are stable, the reactor amplification difficulty is low, the operation flexibility is large, and the product yield and quality can be well guaranteed. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0049] Figure 1 The structure schematic diagram of the device for continuously preparing dichloro pentaerythritol diphosphite provided in Embodiment 2 is shown in the figure.

[0050] In the figure: 1-pentaerythritol suspension preparation kettle; 2-pentaerythritol suspension feed pump; 3-preheater; 4-phosphorus trichloride storage tank; 5-phosphorus trichloride feed pump; 6-premixer; 7- scraper film reactor; 8-condenser; 9-gas-liquid separator; 10-hydrogen chloride tail gas absorption system; 11-mixer; 12-catalyst storage tank; 13-catalyst feed pump. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0052] The purpose of the present application is to provide a method and device for continuously preparing dichloro pentaerythritol diphosphite, so as to solve the problems in the prior art. The yield is high, the energy consumption is low, and the dichloro pentaerythritol diphosphite can be continuously synthesized.

[0053] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0054] Embodiment 1

[0055] The present embodiment provides a method for continuously preparing dichloro pentaerythritol diphosphite, comprising the following steps:

[0056] Step 1, mixing pentaerythritol with an organic solvent to obtain a pentaerythritol suspension;

[0057] Step two, the pentaerythritol suspension and phosphorus trichloride are fed into a scraped-film reactor in series to carry out continuous esterification reaction, the generated HCl gas is discharged from the upper part of each scraped-film reactor, and the reaction liquid discharged from the bottom of the scraped-film reactor flows into the next scraped-film reactor, until the dichloro pentaerythritol diphosphite product solution is discharged from the bottom of the scraped-film reactor, and the esterification reaction temperature is 30-100℃.

[0058] In the present embodiment, the organic solvent preferably includes toluene, xylene, trimethylbenzene, 1,2-dichloropropane, 1,3-dichloropropane or 1,2,3-trichloropropane, and more preferably toluene or 1,2-dichloropropane.

[0059] In the present embodiment, the molar ratio of pentaerythritol to phosphorus trichloride is preferably 1:2-3, and more preferably 1:2.2-2.5. In the present application, the mass ratio of pentaerythritol to organic solvent is preferably 10-20:100, and more preferably 15:100.

[0060] In the present embodiment, the mixed solution obtained by mixing preferably further includes an organic amine catalyst. In the present application, the organic amine catalyst preferably includes one or more of N,N-dimethyl aniline, N,N-dimethyl n-butylamine, N-methyl formamide, N,N-dimethyl cyclohexylamine, triethylamine, N,N-diisopropyl ethylamine, 4-dimethylamino pyridine or pyridine, and more preferably N,N-dimethyl n-butylamine. In the present application, the molar ratio of pentaerythritol to organic amine catalyst is preferably 1:0.01-0.50, and more preferably 1:0.02-0.04.

[0061] In the present embodiment, the esterification reaction is preferably a staged reaction, and the number of stages of the staged reaction is preferably 1-15, more preferably 2-10, and more further preferably 2-7. The present application preferably limits the temperature of different stages according to the number of stages of the staged reaction. Taking the number of stages of the staged reaction as 1-3 as an example, the temperature of each stage is introduced as follows. When the number of stages of the staged reaction is 1, the esterification reaction temperature is 30-90℃, and preferably 50-70℃. When the number of stages of the staged reaction is 2, the temperature of the first stage of the esterification reaction is 30-70℃, and preferably 40-60℃, and the temperature of the second stage of the esterification reaction is 40-100℃, and preferably 50-90℃. When the number of stages of the staged reaction is 3, the temperature of the first stage of the esterification reaction is 30-80℃, and preferably 40-60℃, the temperature of the second stage of the esterification reaction is 40-90℃, and preferably 40-80℃, and the temperature of the third stage of the esterification reaction is 40-100℃, and preferably 40-90℃.

[0062] The multi-stage reaction at different temperatures in the embodiment is conducive to removing the generated hydrogen chloride, promoting the forward movement of the reaction, and thus improving the yield of the dichloro pentaerythritol diphosphite. In the present application, the reaction temperature increases with the increase of the reaction stage number, as long as the generated hydrogen chloride can be removed.

[0063] In the multi-stage series connection, the catalyst is added into the inlet of each stage of the scraped film reactor in a certain proportion, or added into the inlet of some stages of the scraped film reactor.

[0064] In other embodiments, in step two, the pentaerythritol suspension and phosphorus trichloride are premixed by a mixer before entering the scraped film reactor for reaction.

[0065] In other embodiments, in step two, the pentaerythritol suspension or the phosphorus trichloride raw material or the pentaerythritol suspension mixed with the phosphorus trichloride is preheated to 30-60°C before entering the scraped film reactor for reaction; the mixing temperature is preferably 30-60°C, more preferably 40-50°C.

[0066] In other embodiments, the multi-stage series connection of the scraped film reactor, the reaction temperature in the first stage of the scraped film reactor is 30-80°C, the reaction temperature in the second stage of the scraped film reactor is 40-90°C, and the reaction temperature in the third stage and above of the scraped film reactor is 40-100°C.

[0067] In the multi-stage series connection of the scraped film reactor, the phosphorus trichloride is divided into multiple streams and enters each stage of the scraped film reactor or the first stage and part of the subsequent scraped film reactors for reaction.

[0068] The phosphorus trichloride entering each stage of the scraped film reactor is mixed with the pentaerythritol suspension or the material discharged from the previous stage of the scraped film reactor by a mixer before entering the corresponding scraped film reactor.

[0069] The reaction pressure in the scraped film reactor is micro-negative pressure, normal pressure or micro-positive pressure.

[0070] The HCl gas discharged from each stage of the scraped film reactor is condensed by a condenser and gas-liquid separated for recovering the solvent and reactants entrained in the gas phase and returning to the corresponding scraped film reactor.

[0071] In other embodiments, the dichloro pentaerythritol diphosphite solution prepared by using a single-stage scraped film reactor can be returned to the inlet of the scraped film reactor, mixed with the entering pentaerythritol suspension and phosphorus trichloride for cyclic reaction until the desired conversion rate is reached.

[0072] Example Two

[0073] The embodiment provides a device for continuously preparing dichloro pentaerythritol diphosphite, which is used for realizing the method for continuously preparing dichloro pentaerythritol diphosphite in the embodiment one, as shown in the figure, comprising a pentaerythritol suspension preparation kettle 1, a phosphorus trichloride storage tank 4, a premixer 6, a scraped film reactor 7 of one or more stages in series and a hydrogen chloride tail gas absorption system 10. Figure 1 As shown in the figure, the device comprises a pentaerythritol suspension preparation kettle 1, a phosphorus trichloride storage tank 4, a premixer 6, a scraped film reactor 7 of one or more stages in series and a hydrogen chloride tail gas absorption system 10.

[0074] The pentaerythritol suspension preparation kettle 1 is used for preparing pentaerythritol suspension, the phosphorus trichloride storage tank 4 is used for storing phosphorus trichloride, the pentaerythritol suspension preparation kettle 1 is provided with an organic solvent adding port and a pentaerythritol adding port, and the pentaerythritol suspension is prepared by using the organic solvent and the pentaerythritol; in the preferred embodiment, the scraped film reactor 7 is internally provided with a liquid distribution device, the inlet of the scraped film reactor 7 is connected with the internal liquid distribution device; the scraped film reactor 7 is internally provided with a defoaming device, and the released hydrogen chloride gas is discharged from the gas phase outlet after passing through the defoaming device. In the preferred embodiment, the pentaerythritol suspension preparation kettle 1 is provided with a heating jacket, so as to facilitate the adjustment of the configuration temperature of the suspension; the pentaerythritol suspension preparation kettle 1 and the phosphorus trichloride storage tank 4 are communicated with the inlet of the premixer 6, the outlet of the premixer 6 is connected with the inlet of the first-stage scraped film reactor 7, and the gas phase outlet of the scraped film reactor 7 is connected with the gas inlet of the hydrogen chloride tail gas absorption system 10; the pentaerythritol suspension in the pentaerythritol suspension preparation kettle 1 is pumped into the premixer 6 through a pentaerythritol suspension feeding pump 2; the phosphorus trichloride in the phosphorus trichloride storage tank 4 is pumped into the premixer 6 through a phosphorus trichloride feeding pump 5.

[0075] The reaction of the solid-liquid synthesis of pentaerythritol and phosphorus trichloride in the solvent is carried out in the scraped film reactor 7 to generate a gas-liquid product, the reaction is rapid, the scraped film reactor 7 can perform violent mixing on the material, and the contact of the reaction material is increased; the scraped film reactor 7 is very suitable for the solid-liquid reaction system, and there are no problems such as blockage and solid accumulation; the reaction liquid film layer is very thin, the heat transfer area is large and the heat transfer is fast, which is beneficial to precise temperature control; the generated hydrogen chloride can be rapidly separated from the film layer, so that the reaction in the liquid film layer is promoted to the right. The liquid in the scraped film reactor 7 flows from top to bottom by gravity, which can very well control the back mixing and reduce the occurrence of side reactions; the flow direction of the liquid film layer is opposite to the discharge direction of the hydrogen chloride gas, the closer to the end point of the material, the lower the concentration of hydrogen chloride in the gas-liquid two phases, the influence of hydrogen chloride on the reaction is avoided to the greatest extent, which is beneficial to accelerating the reaction speed, controlling the occurrence of side reactions, and making the product obtain a high yield.

[0076] The phosphorus trichloride and the pentaerythritol suspension are continuously reacted in the first or multiple-stage series-connected scraped-film reactor 7, the generated hydrogen chloride gas is discharged from the upper part of each scraped-film reactor 7, and the generated dichloro pentaerythritol diphosphite synthesis solution is discharged from the bottom of each scraped-film reactor 7. The reaction solution discharged from the bottom of the multiple-stage series-connected scraped-film reactor 7 is gradually introduced into the inlet of the next-stage reactor until the dichloro pentaerythritol diphosphite product solution is discharged from the bottom of the last-stage reactor.

[0077] When only one scraped-film reactor 7 is provided, the bottom liquid-phase outlet of the scraped-film reactor 7 is the outlet of the synthesized dichloro pentaerythritol diphosphite product solution;

[0078] When multiple-stage series-connected scraped-film reactors 7 are provided, the bottom liquid-phase outlet of the previous-stage reactor is connected to the inlet of the next-stage scraped-film reactor 7, and the bottom liquid-phase outlet of the last-stage scraped-film reactor 7 is the outlet of the synthesized dichloro pentaerythritol diphosphite product solution. The scraped-film reactor 7 of the previous stage is connected to the scraped-film reactor 7 of the next stage through a mixer 11, the outlet of the phosphorus trichloride feeding pump 5 is connected to the inlet of the mixer 11, and the phosphorus trichloride is divided into multiple streams and introduced into each reactor or participates in the reaction in the first stage and the subsequent partial reactors. The phosphorus trichloride is mixed with the pentaerythritol suspension or the material discharged from the previous-stage reactor through the mixer 11 and then introduced into the corresponding reactor. The multiple-stage series-connected reactors can be subjected to gradient heating to meet the precise control requirements of the reaction temperature at different stages. The multiple-stage series-connected scraped-film reactor 7 has a stage number of 2-15 stages in series, preferably 2-10 stages in series, and more preferably 2-7 stages in series. The reaction pressure in the scraped-film reactor 7 is micro-negative pressure, normal pressure or micro-positive pressure, and is preferably micro-negative pressure. The reaction temperature in the first-stage reactor is preferably 30-80°C, and more preferably 40-60°C. The reaction temperature in the second-stage reactor is preferably 40-90°C, and more preferably 40-80°C. The reaction temperature in the third-stage and subsequent reactors is preferably 40-100°C, and more preferably 40-90°C.

[0079] In addition, in order to improve the synthesis rate, a catalyst storage tank 12 is also provided, the outlet of the catalyst storage tank 12 is connected to a catalyst feeding pump 13, the catalyst feeding pump 13 can pump the catalyst into the pentaerythritol suspension preparation kettle 1 and each scraped-film reactor 7 or some of the scraped-film reactors 7, and the catalyst is added into the inlet of each reactor or some of the reactors in a certain proportion.

[0080] The present application does not need a large vacuum system, and does not need to introduce dry air or nitrogen to assist the hydrogen chloride gas discharge, reduces the exhaust emission, and can well complete the reaction under micro-negative pressure, normal pressure or micro-positive pressure, has good energy saving and environmental protection effect, and has continuous production process, high equipment utilization rate, large production capacity, easy automation operation, stable process parameters, low reactor amplification difficulty, large operation flexibility, and good product yield and quality guarantee.

[0081] In some embodiments, the condenser 8 and the gas-liquid separator 9 are arranged corresponding to each stage of the scraped film reactor 7, the gas phase outlet of the scraped film reactor 7 is connected to the hydrogen chloride tail gas absorption system 10 after passing through the condenser 8 and the gas-liquid separator 9 in turn, and the liquid phase outlet of the gas-liquid separator 9 is connected to the condensate inlet of the corresponding scraped film reactor 7. The hydrogen chloride gas extracted from the upper gas phase outlet of each stage of the scraped film reactor 7 enters the hydrogen chloride tail gas absorption system 10 after being condensed by the condenser 8 and being captured by the gas-liquid separator 9 to carry out the solvent and the reaction material. The liquid captured by the gas-liquid separator 9 returns to the corresponding reactor to return to the reaction system, so as to reduce the waste of raw materials.

[0082] In some embodiments, the inlet of the premixer 6 can be connected to the outlet of the first preheater 3, the phosphorus trichloride feeding pump 5 and / or the pentaerythritol suspension feeding pump 2, the inlet of the pentaerythritol suspension feeding pump 2 is connected to the outlet of the pentaerythritol suspension preparation kettle 1, and the inlet of the pentaerythritol suspension feeding pump 2 is connected to the outlet of the phosphorus trichloride storage tank 4. The first preheater 3 is used for preheating the material before discharging to the premixer 6.

[0083] The outlet of the premixer 6 is connected to the inlet of the scraped film reactor 7 through the second preheater 3, and the second preheater 3 is used for preheating the material before discharging to the scraped film reactor 7; the pentaerythritol suspension, the phosphorus trichloride raw material, or the mixture of the pentaerythritol suspension and the phosphorus trichloride is preheated to 30-60℃ before entering the scraped film reactor 7 for reaction.

[0084] The specific application embodiments are as follows:

[0085] Example 1: Toluene, pentaerythritol were prepared into 15%wt pentaerythritol suspension in pentaerythritol suspension preparation kettle, pumped, preheated to 50°C by preheater, mixed with phosphorus trichloride in premixer, then entered into 3-stage series scraped film reactor for reaction, the molar ratio of pentaerythritol to phosphorus trichloride was 1.0:2.2, the reaction temperature of the first stage reactor was 50-55°C, the reaction temperature of the second stage reactor was 60-65°C, the reaction temperature of the third stage reactor was 75-85°C, the synthesized dichloro pentaerythritol diphosphite product solution was discharged from the bottom of the third stage reactor. The pressure in the reactor was kept slightly negative by suction of the hydrogen chloride tail gas absorption system, the hydrogen chloride gas extracted from the gas phase outlet of the upper part of each stage reactor was condensed by condenser and captured by gas-liquid separator after the solvent and reaction materials were brought out, then entered into the hydrogen chloride tail gas absorption system. The liquid captured by the gas-liquid separator returned to the corresponding reactor to return to the reaction system.

[0086] The dichloro pentaerythritol diphosphite product solution was analyzed, the conversion rate of pentaerythritol was 91.73%, the selectivity of dichloro pentaerythritol diphosphite was 95.35%.

[0087] Example 2: Toluene, pentaerythritol were prepared into 15%wt pentaerythritol suspension in pentaerythritol suspension preparation kettle, pumped, preheated to 50°C by preheater, mixed with phosphorus trichloride in premixer, then entered into 5-stage series scraped film reactor for reaction, the molar ratio of pentaerythritol to phosphorus trichloride was 1.0:2.2, the reaction temperature of the first stage reactor was 50-55°C, the reaction temperature of the second stage and third stage reactor was 60-65°C, the reaction temperature of the fourth stage reactor was 70-75°C, the reaction temperature of the fifth stage reactor was 75-85°C, the synthesized dichloro pentaerythritol diphosphite product solution was discharged from the bottom of the fifth stage reactor. The pressure in the reactor was kept slightly negative by suction of the hydrogen chloride tail gas absorption system, the hydrogen chloride gas extracted from the gas phase outlet of the upper part of each stage reactor was condensed by condenser and captured by gas-liquid separator after the solvent and reaction materials were brought out, then entered into the hydrogen chloride tail gas absorption system. The liquid captured by the gas-liquid separator returned to the corresponding reactor to return to the reaction system.

[0088] The dichloro pentaerythritol diphosphite product solution was analyzed, the conversion rate of pentaerythritol was 95.22%, the selectivity of dichloro pentaerythritol diphosphite was 96.63%.

[0089] Example 3: 1,2-dichloropropane, pentaerythritol and catalyst N,N-dimethyl-n- butylamine were prepared into 15%wt pentaerythritol suspension in pentaerythritol suspension preparation kettle, pumped, preheated to 40°C by preheater, mixed with phosphorus trichloride in premixer and then entered into 4-stage series scraped film reactor for reaction, the molar ratio of pentaerythritol, phosphorus trichloride and catalyst was 1.0:2.2:0.02, the reaction temperature of first stage reactor was 40-45°C, the reaction temperature of second stage reactor was 45-50°C, the reaction temperature of third stage reactor was 55-60°C, the reaction temperature of fourth stage reactor was 60-65°C, the synthesized dichloro pentaerythritol diphosphite product solution was discharged from the bottom of fourth stage reactor. The pressure in the reactor was kept slightly negative by suction of hydrogen chloride tail gas absorption system, the hydrogen chloride gas extracted from the gas phase outlet of the upper part of each stage reactor was condensed by condenser and then entered into hydrogen chloride tail gas absorption system after being captured by gas-liquid separator. The liquid captured by gas-liquid separator was returned to the corresponding reactor to return to the reaction system.

[0090] The dichloro pentaerythritol diphosphite product solution was analyzed, the conversion rate of pentaerythritol was 93.55%, the selectivity of dichloro pentaerythritol diphosphite was 97.45%.

[0091] Example 4: Toluene, pentaerythritol were prepared into 15%wt pentaerythritol suspension in pentaerythritol suspension preparation kettle, pumped, preheated to 50°C by preheater, mixed with 60% proportion of phosphorus trichloride in premixer and then entered into 5-stage series scraped film reactor for reaction, 30% proportion of phosphorus trichloride was mixed with the material discharged from the bottom of first stage reactor in mixer and then entered into second stage reactor for reaction, 10% proportion of phosphorus trichloride was mixed with the material discharged from the bottom of second stage reactor in mixer and then entered into third stage reactor for reaction. The molar ratio of pentaerythritol and phosphorus trichloride was 1.0:2.2, the reaction temperature of first stage reactor was 50-55°C, the reaction temperature of second and third stage reactors was 60-65°C, the reaction temperature of fourth stage reactor was 70-75°C, the reaction temperature of fifth stage reactor was 75-85°C, the synthesized dichloro pentaerythritol diphosphite product solution was discharged from the bottom of fifth stage reactor. The pressure in the reactor was kept slightly negative by suction of hydrogen chloride tail gas absorption system, the hydrogen chloride gas extracted from the gas phase outlet of the upper part of each stage reactor was condensed by condenser and then entered into hydrogen chloride tail gas absorption system after being captured by gas-liquid separator. The liquid captured by gas-liquid separator was returned to the corresponding reactor to return to the reaction system.

[0092] The dichloro pentaerythritol diphosphite product solution was analyzed, the conversion rate of pentaerythritol was 92.35%, the selectivity of dichloro pentaerythritol diphosphite was 96.88%.

[0093] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In conclusion, the content of the present specification should not be understood as the limitation of the present application.

Claims

1. A process for the continuous preparation of dichloro pentaerythritol diphosphite characterized by: The method comprises the following steps: Step 1: mixing pentaerythritol with an organic solvent to obtain a pentaerythritol suspension; Step 2: continuously esterifying the pentaerythritol suspension and phosphorus trichloride in a multi-stage scraped film reactor to generate HCl gas, which is discharged from the upper part of each stage of the scraped film reactor, and the reaction liquid discharged from the bottom of the multi-stage scraped film reactor flows into the next stage of the scraped film reactor until the dichloro pentaerythritol diphosphite product solution is discharged from the bottom of the scraped film reactor, and the esterification reaction temperature is 30-100℃; in step 2, the pentaerythritol suspension or the phosphorus trichloride raw material or the pentaerythritol suspension and phosphorus trichloride mixture is preheated to 30-60℃ before entering the scraped film reactor for reaction; The multi-stage scraped film reactor has a first stage scraped film reactor with a reaction temperature of 30-80℃, a second stage scraped film reactor with a reaction temperature of 40-90℃, and a third stage or more scraped film reactor with a reaction temperature of 40-100℃; In the multi-stage scraped film reactor, the phosphorus trichloride is divided into multiple streams and enters each stage of the scraped film reactor or the first stage and the subsequent stages of the scraped film reactor for reaction; The phosphorus trichloride entering each stage of the scraped film reactor is mixed with the pentaerythritol suspension or the material discharged from the previous stage of the scraped film reactor before entering the corresponding scraped film reactor.

2. The process for the continuous preparation of dichloro pentaerythritol diphosphite according to claim 1 characterized in that: The molar ratio of pentaerythritol to phosphorus trichloride is 1:2-3.

3. The method of continuously producing dichloro pentaerythritol diphosphite according to claim 1, characterized in that: In step 1, the organic solvent is one or more of toluene, xylene, trimethylbenzene, 1,2-dichloropropane, 1,3-dichloropropane, and 1,2,3-trichloropropane.

4. The process for the continuous preparation of dichloro pentaerythritol diphosphite according to claim 1 characterized in that: In step 1, the pentaerythritol suspension contains a catalyst added, and the molar ratio of pentaerythritol to catalyst is 1.0:0.01-0.50; In the multi-stage scraped film reactor, the catalyst is added at a certain proportion from the inlet of each stage of the scraped film reactor or from the inlet of some stages of the scraped film reactor.

5. The method of continuously producing dichloro pentaerythritol diphosphite according to claim 4, characterized in that: The catalyst is one or more of triethylamine, N,N-dimethylbenzylamine, N,N-dimethyl-n-butylamine, N,N-dimethylcyclohexylamine, N,N-diisopropylethylamine, 4-dimethylamino pyridine, and pyridine.

6. The process for the continuous preparation of dichloro pentaerythritol diphosphite according to claim 1 characterized in that: In step 2, the pentaerythritol suspension and phosphorus trichloride are pre-mixed in a mixer before entering the scraped film reactor for reaction.

7. The method of continuously producing dichloro pentaerythritol diphosphite according to claim 1, characterized in that: The reaction pressure in the scraped film reactor is micro-negative pressure, normal pressure, or micro-positive pressure; The HCl gas discharged from each stage of the scraped film reactor is condensed and gas-liquid separated in a condenser to recover the solvent and reactants entrained in the gas phase and return to the corresponding scraped film reactor; The multi-stage scraped film reactor has 2-15 stages in series.

8. The process for the continuous preparation of dichloro pentaerythritol diphosphite according to any one of claims 1 to 7, characterized in that: The device for continuously preparing dichloro pentaerythritol diphosphite comprises a pentaerythritol suspension preparation kettle, a phosphorus trichloride storage tank, a premixer, a plurality of scraped film reactors connected in series, and a hydrogen chloride tail gas absorption system; the pentaerythritol suspension preparation kettle and the phosphorus trichloride storage tank are both in communication with the inlet of the premixer, the outlet of the premixer is connected with the inlet of the first scraped film reactor, the gas phase outlet of the scraped film reactor is connected with the gas inlet of the hydrogen chloride tail gas absorption system; the liquid phase outlet at the bottom of the previous reactor is connected with the inlet of the scraped film reactor in the next stage; the liquid phase outlet at the bottom of the last scraped film reactor is the outlet of the prepared dichloro pentaerythritol diphosphite product solution.

9. The method of continuously producing dichloro pentaerythritol diphosphite according to claim 8, characterized in that: The scraped film reactor is internally provided with a liquid distribution device, and the inlet of the scraped film reactor is connected with the internal liquid distribution device; The scraped film reactor is internally provided with a defoaming device, and the released hydrogen chloride gas is discharged from the gas phase outlet after passing through the defoaming device; Each scraped film reactor is provided with a condenser and a gas-liquid separator, and the gas phase outlet of the scraped film reactor is connected with the hydrogen chloride tail gas absorption system after passing through the condenser and the gas-liquid separator in sequence; the liquid phase outlet of the gas-liquid separator is connected with the condensate inlet of the corresponding scraped film reactor; The inlet of the premixer can be connected with the outlet of the phosphorus trichloride feeding pump and / or the outlet of the pentaerythritol suspension feeding pump through a first preheater, the inlet of the pentaerythritol suspension feeding pump is connected with the outlet of the pentaerythritol suspension preparation kettle, and the inlet of the phosphorus trichloride feeding pump is connected with the outlet of the phosphorus trichloride storage tank; The outlet of the premixer is connected with the inlet of the scraped film reactor through a second preheater; The pentaerythritol suspension preparation kettle is provided with a heating jacket; The scraped film reactor in the previous stage is connected with the scraped film reactor in the next stage through a mixer, and the outlet of the phosphorus trichloride feeding pump is connected with the inlet of the mixer; Further comprising a catalyst storage tank, the outlet of the catalyst storage tank is connected with a catalyst feeding pump, and the catalyst feeding pump can pump catalyst into the pentaerythritol suspension preparation kettle and each scraped film reactor or some of the scraped film reactors.

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