A kind of preparation process of triisooctyl phosphate

Abstract

The present application provides a process for preparing triisooctyl phosphate, which comprises four steps of esterification, deacidification and dealcoholization, pH adjustment and refining. In the esterification process, a microtubular high specific surface area reactor is selected to greatly improve the heat and mass transfer efficiency, reduce the reaction time and the distillation time, and can quickly distill the HCl generated by the reaction out of the reaction system, so as to avoid the dissolution of HCl in isooctyl alcohol and reduce the occurrence of side reactions. In the esterification process, the product yield is significantly improved, the raw material utilization rate is improved, and the high-concentration salt-containing wastewater generated in the pH adjustment process is reduced, which complies with the national environmental protection policy. In the refining process, a falling film distillation tower is selected, and the first condition and the second condition are set for distillation, which can effectively improve the distillation efficiency and the raw material utilization rate, realize large-scale continuous production, reduce the production cost, and reduce the production energy consumption, which complies with the green chemistry concept and the national environmental protection emission standards, and has the advantages of high economic benefits, energy saving and environmental protection, simple actual operation, and easy promotion and implementation.

Description

Technical Field

[0001] The present application belongs to the technical field of chemical raw material production, and specifically relates to a process for preparing tri-isooctyl phosphate. Background Art

[0002] In the prior art, tri(2-ethylhexyl) phosphate (TOP for short) is used as a plasticizer. It has good compatibility, excellent low-temperature flexibility, flame retardancy, and bacteria resistance. It is widely used in plastic and fiber processing. TOP can also be used in the production of hydrogen peroxide by the anthraquinone method to replace hydrogenated terpenoids, making the product high in concentration, high in quality, and low in self-consumption. TOP can also be used in the fields of metal and nuclear element extraction, and is a widely used chemical raw material.

[0003] In the prior art, the production method of trioctyl phosphate in China generally adopts a catalytic esterification method, that is, under the action of a catalyst, isooctyl alcohol and phosphorus oxychloride undergo an esterification reaction, and then the product is obtained by deacidification, dealcoholization, neutralization, water washing, and distillation. The traditional process adopts a kettle esterification reactor, which has low heat and mass transfer efficiency, and the generated HCl cannot be quickly separated from the reactants. The generated HCl will dissolve in the isooctyl alcohol in the reactor, resulting in many side reactions and low product yield. In the alkali neutralization and water washing sections, a large amount of high-concentration salt-containing wastewater is generated, which is difficult to treat. The entire preparation process has more three wastes and does not comply with national environmental protection policies; and the water washing process causes a part of trioctyl phosphate to dissolve in water, resulting in product loss, increased sewage volume, and increased costs, resulting in low product yield, high cost, and a large amount of sewage, which is not conducive to the development of the trioctyl phosphate industry. Therefore, it is urgently necessary to make improvements to achieve efficient, large-scale, and continuous production, thereby increasing unit production capacity, saving energy and reducing consumption, reducing or avoiding the generation of high-concentration salt-containing wastewater, and achieving clean production. Summary of the invention

[0004] The present application aims to solve the problems in the prior art that the traditional production method of trioctyl phosphate is a catalytic esterification method, in which isooctyl alcohol and phosphorus oxychloride react in a kettle esterification reactor, and the product is obtained by deacidification, dealcoholization, neutralization, water washing and distillation in sequence. During the preparation process, the heat and mass transfer efficiency of the reactor is low, the generated HCl will dissolve in the isooctyl alcohol in the reactor, and more side reactions will occur, thereby reducing the product yield. In the alkali neutralization and water washing sections, a large amount of high-concentration salt-containing wastewater will be generated, which does not comply with the national environmental protection policy, has a high production cost and is highly polluting. A preparation process of triisooctyl phosphate is proposed.

[0005] The present application adopts the following scheme, a process for preparing tri-isooctyl phosphate, comprising the following steps:

[0006] Esterification: isooctyl alcohol and phosphorus oxychloride are simultaneously introduced into the reactor at a molar ratio of 1:3.2-6.5, and esterified for 1.5h-2h at 0℃-65℃, normal pressure or (-0.05)MPa-(-0.098)MPa to obtain an esterified liquid;

[0007] Deacidification and dealcoholization: the esterification liquid is quantitatively and continuously fed into a preheated first distillation tower, and distilled for 2h-3h under the conditions of a distillation tower bottom temperature of 60°C-180°C, a distillation tower top temperature of 55°C-150°C, and a tower pressure of ≤8000Pa, to obtain a tower top distillate A and a tower bottom liquid B;

[0008] Adjusting the pH value: transferring the tower bottom liquid B to a pH adjustment column filled with an alkaline substance layer, and neutralizing it for 0.5h-1.5h under the conditions of temperature <50°C and pressure of 2000Pa-5000Pa to obtain a crude trioctyl phosphate;

[0009] Refining: transferring the crude trioctyl phosphate to a second distillation tower, performing a primary distillation under the first condition, and obtaining a tower top distillate C and a tower bottom distillate D after the primary distillation;

[0010] The bottom distillate D is transferred to a third distillation tower, and a secondary distillation is performed under the second condition, and a tower top distillate E and a tower bottom distillate F are obtained after the secondary distillation, and the tower bottom distillate F is refluxed into the second distillation tower. During the secondary distillation, the acid value of the tower top distillate E is detected every 15 minutes. When the acid value of the tower top distillate E reaches a preset standard interval value, the tower top distillate E is discharged to obtain a finished product of trioctyl phosphate;

[0011] In the refining, the second distillation tower and the third distillation tower are both falling film distillation towers.

[0012] In the actual implementation process, TOP has a high boiling point, low vapor pressure, low volatility, low distillation efficiency of the distillation tower, and low distillation efficiency of the traditional plate distillation tower. By adopting a falling film distillation tower, the high-boiling-point trioctyl phosphate crude product is instantly heated and evaporated in the form of a liquid film on the heated tube wall (or plate wall) in the distillation tower, avoiding the side reaction of HCl, H2O and the product at high temperature, reducing the side reaction products, and improving the utilization rate of raw materials.

[0013] In the actual implementation process, during the esterification reaction, a vacuum pump for extracting a liquid film is provided on the reactor. The liquid in the reactor contacts and reacts in the form of a liquid film, and the generated HCl gas can be quickly extracted from the liquid film by the vacuum pump, thereby reducing the dissolution time and solubility of HCl in isooctyl alcohol and reducing by-products.

[0014] In some possible embodiments, in the refining, the first condition is: the temperature of the heat transfer oil at the bottom of the second distillation tower and in the tube sheet of the tower is 110°C-195°C, the temperature at the top of the second distillation tower is 25°C-155°C, and the pressure in the second distillation tower is ≤1000Pa;

[0015] The second condition is: the temperature of the heat transfer oil at the bottom of the third distillation tower and in the tube sheet is 150°C-245°C, the temperature at the top of the third distillation tower is 95°C-195°C, and the pressure in the third distillation tower is ≤300Pa.

[0016] In some possible embodiments, in the esterification, the reactor is a micro-tubular esterification reactor, a tubular esterification reactor, or a combination of the above two esterification reactors, and the surface area of ​​the fluid in the reactor is 104m 2 / m 3 -106 m 2 / m 3 , the thermal conductivity of the reactor is ≥25kW / (m 2 ·K).

[0017] In some possible embodiments, during the esterification, the inner diameter of the pipe in the reactor is 3 mm-150 mm.

[0018] In the actual implementation process, the esterification uses both a microtubular reactor and a tubular reactor. The combination of the two reactors greatly improves the temperature, pressure and other physical quantities in the reactor, increases the driving force for material and energy transmission, reduces the diffusion distance and convection cycle of the fluid, and reduces the mixing time of the liquid, thereby greatly enhancing the mass transfer capacity of the microreactor and avoiding blockage of the pipeline in the reactor, thereby realizing large-scale continuous production. Compared with the traditional kettle esterification reactor, the mass transfer efficiency is increased by 1000-1500 times.

[0019] In the actual implementation process, the reactor material is any one of Hastelloy stainless steel, 316 / 316L stainless steel, carbon steel, silicon carbide, glass, enameled glass, polytetrafluoroethylene, PVC, and nylon. The material can be selected based on comprehensive considerations such as the properties of the reactants, reaction temperature, pressure, and solvent properties.

[0020] In some possible embodiments, in the deacidification and dealcoholization, the top distillate A is isooctyl alcohol containing hydrogen chloride. In the deacidification and dealcoholization, the top distillate A is refluxed to the first distillation tower for cyclic deacidification, and high-purity recovered isooctyl alcohol is obtained after deacidification. In the deacidification and dealcoholization, the high-purity recovered isooctyl alcohol is refluxed to the reactor in the esterification to participate in the esterification reaction.

[0021] In some possible embodiments, the purity of the high-purity recovered isooctyl alcohol is ≥ 99%.

[0022] During the actual implementation process, the high-purity recovered isooctyl alcohol is treated with acid and water removal. The recovered isooctyl alcohol after acid and water removal does not contain HCl and water, and is refluxed to the esterification reaction step, which greatly reduces side reactions and reduces the amount of by-products.

[0023] In the actual implementation process, the uncooled hydrogen chloride gas from the top condenser of the first distillation tower is absorbed by water to produce hydrochloric acid with a concentration of 20%-32%.

[0024] During the actual implementation process, no water washing is required in the deacidification and dealcoholization, which avoids product loss and the generation of high-concentration phosphorus-containing wastewater, and can achieve clean production. Excess isooctyl alcohol in the reaction process can be recovered and converted into high-purity recovered isooctyl alcohol with a concentration greater than 99% after treatment, and the reaction continues in the esterification reaction, which significantly improves the utilization rate of raw materials and significantly reduces the occurrence of side reactions.

[0025] In some possible embodiments, in the pH adjustment, the alkaline substance layer is any one of sodium hydroxide, sodium carbonate, calcium oxide, alkali metal oxides, and alkaline earth metal oxides, or a mixture of more than one of them.

[0026] In some possible embodiments, during the esterification, the reactor is connected to a cooling jacket, and a circulating chilled brine is provided in the cooling jacket. The chilled brine is used to replace the reaction heat to maintain the esterification reaction temperature at 0°C-65°C.

[0027] In some possible embodiments, during the refining, the purity of the finished trioctyl phosphate is ≥99.9%, the water content of the finished trioctyl phosphate is ≤0.02%, the acid value of the finished trioctyl phosphate is ≤0.01 mgKOH / g, the color of the finished trioctyl phosphate is ≤2APHA, and the yield of the finished trioctyl phosphate is 90%-96% based on the theoretical yield.

[0028] Compared with the prior art, this application has the following beneficial effects:

[0029] The present application provides a preparation process of triisooctyl phosphate, which comprises four steps of esterification, deacidification and dealcoholization, pH adjustment and refining. In the esterification process, a microtubular high specific surface area reactor is selected to greatly improve the heat and mass transfer efficiency, reduce the reaction time and the distillation time, and can quickly distill the HCl generated by the reaction out of the reaction system, so as to avoid the dissolution of HCl in isooctyl alcohol and reduce the occurrence of side reactions. In the esterification process, the product yield is significantly improved, the raw material utilization rate is improved, and the high-concentration salt-containing wastewater generated in the pH adjustment process is reduced, which complies with the national environmental protection policy. In the refining process, a falling film distillation tower is selected, and the first condition and the second condition are set for distillation, which can effectively improve the distillation efficiency and the raw material utilization rate. The fractions generated by the distillation can be refluxed, so as to ensure that the final product has a high yield, realize large-scale continuous production, reduce production costs, improve the overall profit rate, and reduce production energy consumption. It complies with the green chemistry concept and the national environmental protection emission standards, and has the advantages of high economic benefits, energy saving and environmental protection, simple actual operation, and easy promotion and implementation. DETAILED DESCRIPTION

[0030] The technical solution provided by the present application is further explained in combination with the contents shown in Examples 1-3.

[0031] In Examples 1-3:

[0032] In step 101, the esterification reactor is a micro-tubular esterification reactor, and the average fluid surface area in the reactor is 104.7 m 2 / m 3 ;

[0033] The average thermal conductivity of the micro-tubular esterification reactor is 25.8kW / (m 2 K);

[0034] In step 103, the alkaline substance layer is prepared by mixing sodium hydroxide, sodium carbonate, and calcium oxide in a mass ratio of 1:5:7.5.

[0035] Example 1

[0036] A process for preparing tri-isooctyl phosphate comprises the following steps:

[0037] Step 101. Esterification: under normal pressure, isooctyl alcohol and phosphorus oxychloride are simultaneously introduced into a micro-tubular esterification reactor at a mass flow rate (kg / h) of a molar ratio of 1:3.5. The reactor is connected to a cooling jacket, and a circulating chilled brine is provided in the cooling jacket to maintain the reaction temperature at 2° C. After reacting for 2 hours, an esterified liquid is obtained;

[0038] Step 102. Deacidification and dealcoholization: maintaining the vacuum pressure at 8000Pa, the esterified liquid obtained in step 101 is continuously and quantitatively added to the first distillation tower with a bottom temperature of 78°C, and when liquid is distilled out from the top of the first distillation tower, a full reflux operation is performed until the bottom temperature, top temperature and pressure of the first distillation tower are constant, the reflux ratio of the first distillation tower is adjusted to 3:1, and the top temperature of the first distillation tower is controlled to be 120°C. The distillate A from the top of the first distillation tower is collected and then washed with alkali and a drying adsorption column to remove HCl gas and H2O contained in the isooctyl alcohol, and after obtaining high-purity recovered isooctyl alcohol, the high-purity recovered isooctyl alcohol is returned to the esterification process as a raw material, and the bottom of the first distillation tower is the bottom liquid X;

[0039] The liquid level of the receiving kettle of the first distillation tower is controlled, and the bottom liquid X is continuously fed into the dealcohol distillation tower with a heating temperature of 110° C. at a constant flow rate of 250 kg / h. When liquid is distilled out from the top of the dealcohol distillation tower, a full reflux operation is performed until the bottom temperature, top temperature and pressure of the dealcohol distillation tower remain constant, and the reflux ratio is adjusted to 4:1, and the top temperature of the dealcohol distillation tower is controlled to be 22° C. The distillate Y of the dealcohol distillation tower is returned to the esterification process in step 101 as a raw material, and the bottom liquid B is in the bottom of the dealcohol distillation tower. The liquid level of the receiving kettle of the dealcohol distillation tower is controlled, and the bottom liquid B is continuously fed into the next process at a constant flow rate of 200 kg / h;

[0040] Step 103. pH value adjustment: the bottom liquid B is transferred to a pH adjustment column filled with an alkaline substance layer, and neutralized for 1.5 hours at 2000 Pa and a temperature of 45° C. in the column. The pH value of the neutralized sample is measured to be 6.8, thereby obtaining a crude product of triisooctyl phosphate;

[0041] Step 104. Distillation: maintaining the pressure in the tower at 1000 Pa, transferring the crude trioctyl phosphate prepared in step 103 to a second distillation tower at a flow rate of 199.5 kg / h, and performing a primary distillation under the first condition, to obtain a tower top distillate C and a tower bottom distillate D after the primary distillation;

[0042] The first condition is: the temperature of the heat transfer oil at the bottom of the second distillation tower and in the tube sheet is 115°C, and the temperature at the top of the second distillation tower is 55°C;

[0043] The pressure in the tower is kept at 300Pa, and the bottom distillate D is transferred to the third distillation tower, and secondary distillation is performed under the second condition. After the distillate flow rate is constant, a full reflux operation is performed. After the temperature and pressure at the bottom of the distillation tower and the top of the distillation tower remain constant, an appropriate reflux ratio is adjusted to control the heating temperature of the heat transfer oil at the bottom of the third distillation tower and the tube sheet in the tower to be 165°C and the top temperature to be 155°C. The bottom distillate F is transferred to the second distillation tower for further distillation. When the acid value of the top distillate E is detected to reach a preset standard interval value, the top distillate E of the third distillation tower is discharged, and the top distillate E is the finished product of trioctyl phosphate after cooling, and its flow rate is 198.8kg / h;

[0044] The obtained trioctyl phosphate finished product has a purity of 99.90%, a water content of 0.0082%, an acid value of 0.0078 mgKOH / g, a color of 2APHA, and a yield of about 94.66%.

[0045] During the esterification reaction in step 101, the amount of isooctyl alcohol is the high-purity recovered isooctyl alcohol from which hydrogen chloride and water are removed during the esterification reaction and the supplemented isooctyl alcohol raw material.

[0046] During the esterification reaction in step 101, the utilization rate of isooctyl alcohol is 99.3%.

[0047] In step 104, the bottom distillate D obtained by distillation in the second distillation tower is purified and then refluxed to step 101 as a raw material for esterification reaction.

[0048] The product obtained by neutralizing and extracting the bottom distillate F obtained by distillation in the third distillation tower in step 104 can be used as a penetrant.

[0049] Example 2

[0050] A process for preparing tri-isooctyl phosphate comprises the following steps:

[0051] Step 101. Esterification: Under vacuum -0.05 MPa, isooctyl alcohol and phosphorus oxychloride are simultaneously and continuously fed into a micro-tubular esterification reactor at a mass flow rate (kg / h) of a molar ratio of 1:4.5. The reactor is connected to a cooling jacket, and a circulating chilled brine is provided in the cooling jacket to maintain the reaction temperature at 15° C. After reacting for 1.5 hours, an esterified liquid is obtained;

[0052] Step 102. Deacidification and dealcoholization: maintaining the vacuum pressure at 7800Pa, the esterified liquid obtained in step 101 is continuously and quantitatively added to the first distillation tower with a bottom temperature of 100°C, and when liquid is distilled out from the top of the first distillation tower, a full reflux operation is performed until the bottom temperature, top temperature and pressure of the first distillation tower remain constant, the reflux ratio of the first distillation tower is adjusted to 4:1, and the top temperature of the first distillation tower is controlled to be 117°C. The distillate A from the top of the first distillation tower is collected and then washed with alkali and a drying adsorption column to remove HCl gas and H2O contained in the isooctyl alcohol, and after obtaining high-purity recovered isooctyl alcohol, the high-purity recovered isooctyl alcohol is returned to the esterification process as a raw material, and the bottom of the first distillation tower is the bottom liquid X;

[0053] The liquid level of the receiving kettle of the first distillation tower is controlled, and the bottom liquid X is continuously fed into the dealcohol distillation tower with a heating temperature of 120° C. at a constant flow rate of 300 kg / h. When liquid is distilled out from the top of the dealcohol distillation tower, a full reflux operation is performed until the bottom temperature, top temperature and pressure of the dealcohol distillation tower remain constant, and the reflux ratio is adjusted to 5:1, and the top temperature of the dealcohol distillation tower is controlled to be 70° C. The distillate Y of the dealcohol distillation tower is returned to the esterification process in step 101 as a raw material, and the bottom liquid B is in the bottom of the dealcohol distillation tower. The liquid level of the receiving kettle of the dealcohol distillation tower is controlled, and the bottom liquid B is continuously fed into the next process at a constant flow rate of 335 kg / h;

[0054] Step 103. pH value adjustment: the bottom liquid B is transferred to a pH adjustment column filled with an alkaline substance layer, and neutralized for 1.2 hours at 3000 Pa and a temperature of 42° C. in the column. The pH value of the neutralized sample is measured to be 7, thereby obtaining a crude product of triisooctyl phosphate;

[0055] Step 104. Distillation: maintaining the pressure in the tower at 850 Pa, transferring the crude trioctyl phosphate prepared in step 103 to a second distillation tower at a flow rate of 334 kg / h, and performing a primary distillation under the first condition, to obtain a tower top distillate C and a tower bottom distillate D after the primary distillation;

[0056] The first condition is: the temperature of the heat transfer oil at the bottom of the second distillation tower and in the tube sheet of the tower is 135°C, and the temperature at the top of the second distillation tower is 85°C;

[0057] The pressure in the tower is kept at 285Pa, and the bottom distillate D is transferred to the third distillation tower, and secondary distillation is performed under the second condition. After the distillate flow rate is constant, a full reflux operation is performed. After the temperature and pressure at the bottom of the distillation tower and the top of the distillation tower remain constant, the reflux ratio is adjusted to 5:1, and the heating temperature of the heat transfer oil at the bottom of the third distillation tower and the tube sheet in the tower is controlled to be 185°C and the top temperature is 188°C. The bottom distillate F is transferred to the second distillation tower for further distillation. When the acid value of the top distillate E is detected to reach the preset standard interval value, the top distillate E of the third distillation tower is discharged, and the top distillate E is the finished product of trioctyl phosphate after cooling, and its flow rate is 304kg / h;

[0058] The obtained trioctyl phosphate finished product has a purity of 99.92%, a water content of 0.0065%, an acid value of 0.0083 mgKOH / g, a color of 2APHA, and a yield of about 90.91%.

[0059] During the esterification reaction in step 101, the amount of isooctyl alcohol is the high-purity recovered isooctyl alcohol from which hydrogen chloride and water are removed during the esterification reaction and the supplemented isooctyl alcohol raw material.

[0060] During the esterification reaction in step 101, the utilization rate of isooctyl alcohol is 99.5%.

[0061] In step 104, the bottom distillate D obtained by distillation in the second distillation tower is purified and then refluxed to step 101 as a raw material for esterification reaction.

[0062] The product obtained by neutralizing and extracting the bottom distillate F obtained by distillation in the third distillation tower in step 104 can be used as a penetrant.

[0063] Example 3

[0064] A process for preparing tri-isooctyl phosphate comprises the following steps:

[0065] Step 101. Esterification: Under normal pressure, isooctyl alcohol and phosphorus oxychloride are continuously and constantly fed into a micro-tubular esterification reactor at a mass flow rate (kg / h) of a molar ratio of 1:5.5. The reactor is connected to a cooling jacket, and a circulating chilled brine is provided in the cooling jacket to maintain the reaction temperature at 52° C. After reacting for 2 hours, an esterified liquid is obtained;

[0066] Step 102. Deacidification and dealcoholization: maintaining the vacuum pressure at 7000 Pa, the esterified liquid obtained in step 101 is continuously and quantitatively added to the first distillation tower with a bottom temperature of 140° C., and when liquid is distilled out from the top of the first distillation tower, a full reflux operation is performed until the bottom temperature, top temperature and pressure of the first distillation tower remain constant, the reflux ratio of the first distillation tower is adjusted to 3:1, and the top temperature of the first distillation tower is controlled to be 125° C. The distillate A from the top of the first distillation tower is collected and then washed with alkali and a drying adsorption column to remove HCl gas and H2O contained in the isooctyl alcohol, and after obtaining high-purity recovered isooctyl alcohol, the high-purity recovered isooctyl alcohol is returned to the esterification process as a raw material, and the bottom of the first distillation tower is the bottom liquid X;

[0067] The liquid level of the receiving kettle of the first distillation tower is controlled, and the bottom liquid X is continuously fed into the dealcohol distillation tower with a heating temperature of 180° C. at a constant flow rate of 125 kg / h. When liquid is distilled out from the top of the dealcohol distillation tower, a full reflux operation is performed until the bottom temperature, top temperature and pressure of the dealcohol distillation tower remain constant, and the reflux ratio is adjusted to 4:1, and the top temperature of the dealcohol distillation tower is controlled to be 135° C. The distillate Y of the dealcohol distillation tower is returned to the esterification process in step 101 as a raw material, and the bottom liquid B is in the bottom of the dealcohol distillation tower. The liquid level of the receiving kettle of the dealcohol distillation tower is controlled, and the bottom liquid B is continuously fed into the next process at a constant flow rate of 119 kg / h;

[0068] Step 103. pH value adjustment: the bottom liquid B is transferred to a pH adjustment column filled with an alkaline substance layer, and neutralized for 2 hours at 5500 Pa and a temperature in the column of 45° C. The pH value of the neutralized sample is measured to be 7, thereby obtaining a crude product of triisooctyl phosphate;

[0069] Step 104. Distillation: maintaining the pressure in the tower at 780 Pa, transferring the crude trioctyl phosphate prepared in step 103 to a second distillation tower at a flow rate of 180 kg / h, and performing a primary distillation under the first condition, to obtain a tower top distillate C and a tower bottom distillate D after the primary distillation;

[0070] The first condition is: the temperature of the heat transfer oil at the bottom of the second distillation tower and in the tube sheet is 185°C, and the temperature at the top of the second distillation tower is 145°C;

[0071] The pressure in the tower is kept at 270Pa, and the bottom distillate D is transferred to the third distillation tower, and secondary distillation is performed under the second condition. After the distillate flow rate is constant, a full reflux operation is performed. After the temperature and pressure at the top of the distillation tower are constant, the reflux ratio is adjusted to 5:1, and the heating temperature of the heat transfer oil at the bottom of the third distillation tower and the tube sheet in the tower is controlled to be 195°C, and the top temperature is 190°C. The bottom distillate F is transferred to the second distillation tower for further distillation. When the acid value of the top distillate E is detected to reach the preset standard interval value, the top distillate E of the third distillation tower is discharged, and the top distillate E is the finished product of trioctyl phosphate after cooling, and its flow rate is 107kg / h;

[0072] The obtained trioctyl phosphate finished product has a purity of 99.90%, a water content of 0.0067%, an acid value of 0.0058 mgKOH / g, a color of 2APHA, and a yield of about 90.77%.

[0073] During the esterification reaction in step 101, the amount of isooctyl alcohol is the high-purity recovered isooctyl alcohol from which hydrogen chloride and water are removed during the esterification reaction and the supplemented isooctyl alcohol raw material.

[0074] During the esterification reaction in step 101, the utilization rate of isooctyl alcohol is 99.7%.

[0075] In step 104, the bottom distillate D obtained by distillation in the second distillation tower is purified and then refluxed to step 101 as a raw material for esterification reaction.

[0076] The product obtained by neutralizing and extracting the bottom distillate F obtained by distillation in the third distillation tower in step 104 can be used as a penetrant.

[0077] It can be seen from the tri-isooctyl phosphate prepared in batches in Examples 1-3 that the present application provides a method for preparing tri-isooctyl phosphate, which includes four steps: esterification, deacidification and dealcoholization, pH adjustment, and refining. In the esterification process, a microtubular high specific surface area reactor is selected to greatly improve the heat and mass transfer efficiency, reduce the reaction time and distillation time, and quickly distill the HCl generated by the reaction out of the reaction system to avoid HCl dissolving in isooctyl alcohol and reduce the occurrence of side reactions. The product yield is significantly improved during the esterification process, and the raw material utilization rate is improved. The purity of the obtained tri-isooctyl phosphate finished product is greater than 99%, the water content is less than 0.001%, and the raw material utilization rate is greater than 99%. The finished product yield is greater than 90%, which significantly reduces the side reactions occurring in the production process, reduces the high-concentration salt-containing wastewater generated in the pH adjustment process, and complies with the national environmental protection policy. In the refining process, a falling film distillation tower is selected, and the first condition and the second condition are set for distillation, which can effectively improve the distillation efficiency and the utilization rate of raw materials. The fractions produced by the distillation can be refluxed to ensure that the final product has a high yield, realize large-scale continuous production, reduce production costs, improve the overall profit margin, and reduce production energy consumption. It complies with the green chemistry concept and national environmental protection emission standards, and has the advantages of high economic benefits, energy saving and environmental protection, simple actual operation, and easy promotion and implementation.

[0078] The above are only embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for preparing tri-isooctyl phosphate, characterized in that: The following steps are involved: Esterification: isooctyl alcohol and phosphorus oxychloride are simultaneously introduced into the reactor at a molar ratio of 1:3.2-6.5, and esterified for 1.5h-2h at 0℃-65℃, normal pressure or (-0.05)MPa-(-0.098)MPa to obtain an esterified liquid; Deacidification and dealcoholization: the esterification liquid is quantitatively and continuously fed into a preheated first distillation tower, and distilled for 2h-3h under the conditions of a distillation tower bottom temperature of 60°C-180°C, a distillation tower top temperature of 55°C-150°C, and a tower pressure of ≤8000Pa, to obtain a tower top distillate A and a tower bottom liquid B; Adjusting the pH value: transferring the tower bottom liquid B to a pH adjustment column filled with an alkaline substance layer, and neutralizing it for 0.5h-1.5h under the conditions of temperature <50°C and pressure of 2000Pa-5000Pa to obtain a crude trioctyl phosphate; Refining: transferring the crude trioctyl phosphate to a second distillation tower, performing a primary distillation under the first condition, and obtaining a tower top distillate C and a tower bottom distillate D after the primary distillation; The bottom distillate D is transferred to a third distillation tower, and a secondary distillation is performed under the second condition, and a tower top distillate E and a tower bottom distillate F are obtained after the secondary distillation, and the tower bottom distillate F is refluxed into the second distillation tower. During the secondary distillation, the acid value of the tower top distillate E is detected every 15 minutes. When the acid value of the tower top distillate E reaches a preset standard interval value, the tower top distillate E is discharged to obtain a finished product of trioctyl phosphate; In the refining, the second distillation tower and the third distillation tower are both falling film distillation towers.

2. A process for preparing tri-isooctyl phosphate according to claim 1, characterized in that: In the refining, the first condition is: the temperature of the heat transfer oil at the bottom of the second distillation tower and in the tube sheet of the tower is 110°C-195°C, the temperature at the top of the second distillation tower is 25°C-155°C, and the pressure in the second distillation tower is ≤1000Pa; The second condition is: the temperature of the heat transfer oil at the bottom of the third distillation tower and in the tube sheet is 150°C-245°C, the temperature at the top of the third distillation tower is 95°C-195°C, and the pressure in the third distillation tower is ≤300Pa.

3. A process for preparing tri-isooctyl phosphate according to claim 1, characterized in that: In the esterification, the reactor is a micro-tubular esterification reactor, a tubular esterification reactor or a combination of the above two esterification reactors, and the surface area of ​​the fluid in the reactor is 104m 2 / m 3 -106 m 2 / m 3 , the thermal conductivity of the reactor is ≥25kW / (m 2 ·K).

4. A process for preparing tri-isooctyl phosphate according to claim 3, characterized in that: In the esterification, the inner diameter of the pipe in the reactor is 3 mm-150 mm.

5. A process for preparing tri-isooctyl phosphate according to claim 1, characterized in that: In the deacidification and dealcoholization, the top distillate A is isooctyl alcohol containing hydrogen chloride. In the deacidification and dealcoholization, the top distillate A is refluxed to the first distillation tower for cyclic deacidification, and high-purity recovered isooctyl alcohol is obtained after deacidification. In the deacidification and dealcoholization, the high-purity recovered isooctyl alcohol is refluxed to the reactor in the esterification to participate in the esterification reaction.

6. A process for preparing tri-isooctyl phosphate according to claim 5, characterized in that: The purity of the high-purity recovered isooctyl alcohol is ≥99%.

7. A process for preparing tri-isooctyl phosphate according to claim 1, characterized in that: In the pH adjustment, the alkaline substance layer is any one of sodium hydroxide, sodium carbonate, calcium oxide, alkali metal oxides, and alkaline earth metal oxides, or a mixture of more than one of them.

8. A process for preparing tri-isooctyl phosphate according to claim 1, characterized in that: In the esterification, the reactor is connected to a cooling jacket, and a circulating chilled brine is provided in the cooling jacket. The chilled brine is used to replace the reaction heat to maintain the esterification reaction temperature at 0°C-65°C.

9. A process for preparing tri-isooctyl phosphate according to claim 1, characterized in that: In the refining, the purity of the finished trioctyl phosphate is ≥99.9%, the water content of the finished trioctyl phosphate is ≤0.02%, the acid value of the finished trioctyl phosphate is ≤0.01 mgKOH / g, the color of the finished trioctyl phosphate is ≤2APHA, and the yield of the finished trioctyl phosphate is 90%-96% calculated based on the theoretical yield.