Continuous preparation process of triisobutyl phosphate

Abstract

The invention provides a continuous preparation process of triisobutyl phosphate, which comprises four steps of esterification, deacidification and dealcoholization, refining and isobutanol recovery, in the esterification process, the specific surface area of fluid in a reactor is increased, the reaction rate is increased, the conversion rate of raw materials is ensured, the use of an acidic catalyst in the esterification process is avoided, and the yield of the product is improved. The production of by-products such as HCl in the esterification process is reduced, the alkali washing column is used for replacing the water washing process, the water washing process and the alkali neutralization process can be integrated into one process, the production of phosphorus-containing and acid-containing wastewater is reduced, the wastewater treatment cost is greatly reduced, excessive isobutanol is recycled in the dealcoholization process, and the production cost is reduced. Raw material waste caused in the washing process is avoided, the utilization rate of the raw materials is increased, production energy consumption is reduced, the green chemistry concept and the national environment-friendly emission standard are met, and the method has the advantages of being high in economic benefit, energy-saving, environment-friendly, simple in actual operation and convenient to popularize and implement.

Description

Technical Field

[0001] The present application belongs to the technical field of chemical raw material production, and specifically relates to a continuous preparation process of triisobutyl phosphate. Background Art

[0002] In the prior art, triisobutyl phosphate has a variety of uses in industry, including as a textile auxiliary, penetrant, dye auxiliary, as well as in defoamers and penetrants. It is widely used in printing and dyeing, inks, construction, oil field auxiliary and other fields.

[0003] In the prior art, the production method of triisobutyl phosphate includes the steps of esterification, dealcoholization, acid removal, neutralization, water washing and distillation. As shown in the patent application document with patent number CN101704839B, in the prior art, the production method of triisobutyl phosphate generally adopts a catalytic esterification method, that is, under the action of a catalyst, isobutyl alcohol and phosphorus oxychloride undergo an esterification reaction to increase the reaction rate of the esterification reaction, reduce the reaction temperature, and improve the product quality. After the esterification is completed, the product is obtained by deacidification, dealcoholization, neutralization, water washing and distillation. However, in the actual implementation process, the addition of a catalyst in the esterification process may cause The esterification process has many fatal defects. On the one hand, the commonly used esterification catalysts are usually acidic catalysts, which produce hydrogen chloride gas during the esterification process. The subsequent alkali neutralization and water washing process will produce a large amount of high-concentration hydrochloric acid and phosphorus-containing wastewater, which greatly increases the cost of wastewater treatment. On the other hand, while catalyzing the main reaction, the catalyst also catalyzes and accelerates the side reaction, resulting in a decrease in product volume and a decrease in raw material utilization rate. During the esterification process, a part of the isobutanol is not reacted and dissolved in the water, which seriously wastes raw materials, increases recovery costs, reduces raw material utilization, and increases production energy consumption, which violates the concept of green chemistry. Therefore, improvements are urgently needed. Summary of the invention

[0004] The present application aims to solve the technical problems that in the prior art, during the industrial preparation process of triisobutyl phosphate, a catalyst needs to be added during the esterification process to increase the reaction rate and product yield, but the commonly used catalyst is usually an acidic catalyst. During the esterification process, a large amount of HCl will be produced, and the industrial wastewater needs to be washed with water and treated with alkali neutralization before it can be discharged, which does not comply with the national environmental protection policy. In addition, during the washing process, part of the excess isobutanol will be dissolved in the water, resulting in serious waste of raw materials, low conversion rate, and significantly increased production costs. A continuous preparation process for triisobutyl phosphate is proposed.

[0005] The present application adopts the following scheme, a continuous preparation process of triisobutyl phosphate, comprising the following steps:

[0006] Step 101. Esterification:

[0007] Isobutanol and phosphorus oxychloride are simultaneously introduced into the reactor at a flow ratio of 2:7-10, and esterification is performed for 3h-5h at 5-55°C to obtain an esterified liquid;

[0008] Step 102. Deacidification and dealcoholization:

[0009] The esterified liquid prepared in step 101 is cooled and allowed to stand for 1 h to 2 h, and then quantitatively and continuously transported to a preheated dealcoholization tower, and distilled for 2 h to 3 h under the conditions of a tower bottom temperature of 60° C. to 140° C., a tower top temperature of 5° C. to 30° C., and a tower internal pressure of (-0.01) MPa to (-0.098) MPa, to distill out a recoverable composition and crude triisobutyl phosphate from the tower top and the tower bottom, respectively;

[0010] Step 103. Refining:

[0011] The crude triisobutyl phosphate prepared in step 102 is transferred to a primary distillation tower, which is a kettle-type distillation tower. During the primary distillation process of the primary distillation tower, the primary tower top distillate is condensed and collected and stored, and the primary tower bottom distillate is directly transported to a secondary distillation tower;

[0012] The secondary distillation tower is a kettle-type distillation tower. During the distillation process of the secondary distillation tower, the front fraction at the top of the secondary tower is collected, stored and refluxed to the primary distillation tower. When the acid value of the distillate at the top of the secondary tower reaches the standard value of the preset interval, the distillate at the top of the secondary tower is condensed and collected and stored, which is the refined triisobutyl phosphate. The reaction is completed and the acid value of the product is ≤0.01 mgKOH / g.

[0013] Step 104. Isobutanol recovery

[0014] The recyclable composition obtained in step 102 and the collected liquid at the top of the primary distillation tower obtained in step 103 are sequentially deacidified and dried through an alkali washing column and a drying column. Under the conditions of a column pressure of (-0.096) MPa-(-0.098) MPa and an elution temperature of 25°C-60°C, the pH value is adjusted to 6-8 to obtain recovered isobutanol, which is refluxed into the reactor in step 101 to continue the cyclic reaction.

[0015] In one embodiment, in step 101, the reactor is a microchannel reactor, a tubular reactor, or a composite esterification reactor, and the specific surface area of ​​the fluid in the reactor is 104m 2 / m 3 -106m 2 / m 3 .

[0016] In one embodiment, in step 101, the thermal conductivity of the reactor is ≥ 25 kW / (m 2 ·K).

[0017] In actual implementation, by selecting a microchannel esterification reactor and increasing the specific surface area of ​​the fluid in the reactor, the heat exchange efficiency between the reactants and the wall in the microchannel can be improved. In addition, the heat transfer coefficient of the microreactor is very large, and the optimal heat transfer coefficient can reach 25kW / (m 2 ·K), the heat released during the reaction can be absorbed in time, the reaction temperature fluctuates little and is stable, and hot spots are avoided;

[0018] Furthermore, the characteristic size of microchannel reactors is much smaller than that of conventional reactors, which increases the physical quantities such as temperature and pressure in the microreactor, increases the driving force of material and energy transmission, and increases the driving force of mass transfer. The smaller scale of the microreactor reduces the diffusion distance and convection cycle of the fluid, reduces the mixing time of the liquid, and thus greatly enhances the mass transfer capacity of the microreactor.

[0019] In one embodiment, in step 101, 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 5°C-55°C.

[0020] In the actual implementation process, a cooling jacket is provided on the reactor, a circulating refrigerated brine is arranged in the cooling jacket, a temperature sensor is provided in the reactor, and the flow rate of the circulating refrigerated brine is controlled by a PLC program. When the temperature measured by the temperature sensor in the reactor exceeds the preset standard interval value, the PLC program can adjust the flow rate of the circulating refrigerated brine, thereby realizing the effective replacement and precise regulation of the large amount of heat energy generated during the esterification reaction, so as to ensure that the temperature in the reactor is in a dynamic equilibrium state, ensure the reaction rate and the raw material conversion rate, and greatly optimize the conditions of the esterification reaction to meet the requirements of high efficiency, safety and environmental protection in chemical production.

[0021] In one embodiment, in step 101, the conversion rate of isobutanol during the esterification reaction is ≥ 83.3% based on the theoretical yield.

[0022] In one embodiment, the purity of the recovered isobutanol prepared in step 104 is ≥ 99%.

[0023] In one embodiment, in step 104, the filler in the alkali washing column is any one of alkalis such as sodium hydroxide, sodium carbonate, calcium oxide, and alkali metal oxides, or a mixture of more than one; the filler in the drying column is any one of molecular sieves, activated carbon, silica gel, flake caustic soda, calcium oxide, sodium sulfate, and calcium chloride, or a mixture of more than one.

[0024] In one embodiment, in step 103, during the initial distillation process of the primary distillation tower, the bottom temperature is 110°C-140°C, the top temperature is 5°C-30°C, and the initial distillation pressure is (-0.01MPa)-(-0.099MPa); during the secondary distillation process of the distillation tower, the bottom temperature is 150°C-160°C, the top temperature is 95°C-125°C, and the secondary distillation pressure is (-0.01MPa)-(-0.099MPa).

[0025] In one embodiment, in step 103, the purity of the refined triisobutyl phosphate is ≥99.9%, the water content is ≤0.2%, the color is ≤5APHA, and the yield of the refined triisobutyl phosphate is 90%-96% calculated based on the theoretical yield.

[0026] In the actual implementation process, crude triisobutyl phosphate does not need to be neutralized and dried, but is directly distilled and refined, which avoids the loss of raw materials during the neutralization and drying process, reduces the occurrence of side reactions, and significantly improves the conversion rate of raw materials in the production process of triisobutyl phosphate, the yield of the esterification reaction, and the purity of the product.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] The present application provides a continuous preparation process of triisobutyl phosphate, which includes four steps of esterification, deacidification and dealcoholization, refining and isobutyl alcohol recovery. In the esterification process, the specific surface area of ​​the fluid in the reactor is increased to improve the reaction rate, ensure the conversion rate of the raw materials, avoid the use of acidic catalysts in the esterification process, reduce the by-product of chloroisobutyl alcohol produced by HCl and isobutyl alcohol in the esterification process, and reduce the by-products such as phosphoric acid diester and polyester generated by H2O generated by the esterification process; crude tributyl phosphate is directly distilled and purified (or distilled and purified after passing through an alkali washing column) to obtain a qualified product; the water washing and alkali neutralization process can be replaced by an alkali washing column. The two processes are integrated into one process, the generation of phosphorus-containing and acid-containing wastewater is reduced, and the wastewater treatment cost is greatly reduced; and in the process of dealcoholization, the excess isobutyl alcohol is recycled and utilized; high-purity recycled isobutyl alcohol is obtained by alkali washing column treatment, the contents of HCl and H2O in the recycled isobutyl alcohol are reduced, the side reaction is reduced, and the amount of by-products is reduced; the improved process technology of the present invention avoids the waste of raw materials caused by the water washing process, improves the utilization rate of raw materials, reduces production energy consumption, conforms to the green chemistry concept and the national environmental protection emission standards, has the advantages of high economic benefit, energy saving and environmental protection, simple actual operation, and easy promotion and implementation. DETAILED DESCRIPTION

[0029] The present technical solution is further illustrated in combination with Examples 1-3 and Comparative Example 1.

[0030] The reactor used in Examples 1-3 and Comparative Example 1 is a microchannel reactor, and the average specific surface area of ​​the fluid in the reactor is 105.4 m 2 / m 3 .

[0031] In Examples 1-3 and Comparative Example 1, the input amount of isobutanol with a purity of ≥99.9% is 1 t, and the rest is originally input according to the preset value.

[0032] In Example 1-3, the filler in the alkali washing column is a composition in which hydroxide, sodium carbonate and calcium oxide are mixed in a mass ratio of 1:1:1; the filler in the drying column is a composition in which activated carbon, silica gel, calcium oxide, sodium sulfate and calcium chloride are mixed in a mass ratio of 1:1:1:1:1.

[0033] Example 1

[0034] A continuous preparation process of triisobutyl phosphate comprises the following steps:

[0035] Step 101. Esterification:

[0036] Under normal pressure, isobutanol and phosphorus oxychloride are continuously and constantly fed into the reactor at a mass flow rate (kg / hr) ratio of 2:9.5. The reactor is provided with a cooling jacket, and the cooling jacket is filled with circulating frozen brine. The frozen brine can control the average reaction temperature in the reactor at 10.7°C. After esterification for 3.5 hours, the esterified liquid is obtained.

[0037] Step 102. Deacidification and dealcoholization:

[0038] The esterified liquid prepared in step 101 is cooled and allowed to stand for 1 hour, and then quantitatively and continuously transported to a preheated dealcoholization tower, and distilled for 2.5 hours under the conditions of a tower bottom temperature of 85° C., a tower top temperature of 9° C., a tower internal pressure of -0.08 MPa, and a reflux ratio of 350 kg / h, and a recoverable composition and crude triisobutyl phosphate are distilled out from the top and bottom of the dealcoholization tower, respectively;

[0039] Step 103. Refining:

[0040] The crude triisobutyl phosphate prepared in step 102 is quantitatively input into the primary distillation tower at a flow rate of 380 kg / hr. The primary distillation tower is a kettle-type distillation tower. During the initial distillation process of the primary distillation tower, the pressure in the primary distillation tower is -0.08 MPa, the bottom temperature is 125°C, the top temperature is 8°C, and the reflux ratio is 370 kg / h. When there is distillate at the top of the primary distillation tower, a full reflux operation is performed. After the top temperature and pressure of the bottom of the primary distillation tower remain constant, the primary top distillate is condensed, collected, stored, and analyzed for components and their corresponding contents. According to the components and contents of the primary top distillate, when the isobutanol content is higher than the preset interval value, it is refluxed to the deacidification and dealcoholization tower kettle in step 102. When the isobutanol content is lower than the preset interval value, it is transported to the next step, and then the primary bottom distillate is directly transported to the secondary distillation tower;

[0041] The secondary distillation tower is a kettle-type distillation tower. During the secondary distillation process of the secondary distillation tower, the pressure in the distillation tower is -0.08MPa, the bottom temperature is 155°C, the top temperature is 110°C, and the reflux ratio is 360kg / h. When the top and bottom temperatures and pressures of the distillation tower are constant, a full reflux operation is performed, and the front fraction of the secondary tower top is collected and stored and refluxed to the primary distillation tower; when the acid value of the secondary tower top distillate reaches the preset range standard value, the secondary tower top distillate is condensed and collected and stored, which is refined triisobutyl phosphate, and the secondary tower bottom distillate is used to prepare phosphate ester penetrants;

[0042] Step 104. Isobutanol recovery

[0043] The recyclable composition obtained in step 102 and the collected liquid at the top of the primary distillation tower obtained in step 103 are circulated in sequence through an alkali washing column and a drying column at an average flow rate of 500 kg / h for deacidification and drying. During the deacidification and drying process, the pressure in the column is -0.096 MPa and the elution temperature is 25°C. After the pH value is adjusted to 7 and the mixture is allowed to stand for 14 hours, isobutanol is recovered. The recovered isobutanol is refluxed into the reactor in step 101 and the cyclic reaction is continued until the reaction is completed. It is measured that the purity of the recovered isobutanol is 99.01%.

[0044] In summary, the flow rate of the secondary tower top distillate (i.e., refined triisobutyl phosphate) is 325 kg / h, the acid value of the secondary tower top distillate is 0.0078 mgKOH / g, the secondary tower top distillate is refined triisobutyl phosphate with a purity of 99.90%, the water content of the secondary tower top distillate is 0.0082%, the color is 2APHA, and based on the theoretical difference rate, the esterification reaction yield is 94%, the conversion rate of 1 t of isobutyl alcohol with a purity ≥99.9% is 86.8%, and the esterification reaction time is 4.7 h.

[0045] Example 2

[0046] A continuous preparation process of triisobutyl phosphate comprises the following steps:

[0047] Step 101. Esterification:

[0048] Under vacuum -0.05MPa, isobutanol and phosphorus oxychloride are continuously and constantly fed into the reactor at a mass flow rate (kg / hr) ratio of 2:7.7. The reactor is provided with a cooling jacket, and the cooling jacket is filled with circulating frozen brine. The frozen brine can control the average reaction temperature in the reactor at 25.8°C. After esterification for 4.2h, the esterified liquid is obtained.

[0049] Step 102. Deacidification and dealcoholization:

[0050] The esterified liquid prepared in step 101 was cooled and allowed to stand for 1.5 hours, and then quantitatively and continuously transported to a preheated dealcoholization tower, and distilled for 2.7 hours under the conditions of a tower bottom temperature of 78° C., a tower top temperature of 8° C., a tower pressure of -0.075 MPa, and a reflux ratio of 337 kg / h, and a recoverable composition and crude triisobutyl phosphate were distilled out from the top and bottom of the dealcoholization tower, respectively;

[0051] Step 103. Refining:

[0052] The crude triisobutyl phosphate prepared in step 102 is quantitatively input into the primary distillation tower at a flow rate of 350 kg / hr. The primary distillation tower is a kettle-type distillation tower. During the initial distillation process of the primary distillation tower, the pressure in the primary distillation tower is -0.085 MPa, the bottom temperature is 120°C, the top temperature is 9°C, and the reflux ratio is 375 kg / h. When there is distillate at the top of the primary distillation tower, the primary top distillate is condensed and collected and stored, and a total reflux operation is performed. After the top temperature and pressure of the primary distillation tower bottom remain constant, the primary top distillate is condensed and collected and stored, and the components and their corresponding contents are analyzed. According to the components and contents of the primary top distillate, when the isobutanol content is higher than the preset interval value, it is refluxed to the deacidification and dealcoholization tower kettle in step 102. When the isobutanol content is lower than the preset interval value, it is transported to the next step, and then the primary bottom distillate is directly transported to the secondary distillation tower;

[0053] The secondary distillation tower is a kettle-type distillation tower. During the secondary distillation process of the secondary distillation tower, the front fraction at the top of the secondary tower is collected, stored and refluxed to the primary distillation tower. The pressure in the distillation tower is -0.08MPa, the bottom temperature is 158°C, the top temperature is 115°C, and the reflux ratio is 365kg / h. When the top and bottom temperatures and pressures of the distillation tower are constant, a full reflux operation is performed. When the acid value of the distillate at the top of the secondary tower reaches the standard value of the preset interval, the distillate at the top of the secondary tower is condensed and collected and stored, which is refined triisobutyl phosphate.

[0054] Step 104. Isobutanol recovery

[0055] The dealcoholized esterified liquid prepared in step 102 is circulated at an average flow rate of 350 kg / h and sequentially passed through an alkali washing column and a drying column for deacidification and drying. During the deacidification and drying process, the pressure in the column is -0.097 MPa and the elution temperature is 32°C. After the pH value is adjusted to 7 and the liquid is allowed to stand for 12 hours, isobutanol is recovered and refluxed into the reactor in step 101. The cyclic reaction is continued until the reaction is completed. It is measured that the purity of the recovered isobutanol is 99.00%.

[0056] In summary, the flow rate of the secondary tower top distillate (i.e., refined triisobutyl phosphate) is 312 kg / h, the acid value of the secondary tower top distillate is 0.0083 mgKOH / g, the secondary tower top distillate is refined triisobutyl phosphate with a purity of 99.92%, the water content of the secondary tower top distillate is 0.0065%, the color is 2APHA, and based on the theoretical difference rate, the esterification reaction yield is 90%, the conversion rate of 1 t of isobutyl alcohol with a purity ≥99.9% is 84.3%, and the esterification reaction time is 4.2 h.

[0057] Example 3

[0058] A continuous preparation process of triisobutyl phosphate comprises the following steps:

[0059] Step 101. Esterification:

[0060] Under vacuum -0.05MPa, isobutanol and phosphorus oxychloride are continuously and constantly fed into the reactor at a mass flow rate (kg / hr) ratio of 2:8.3. The reactor is provided with a cooling jacket, and the cooling jacket is filled with circulating frozen brine. The frozen brine can control the average reaction temperature in the reactor at 41.5°C. After esterification for 4.7h, the esterified liquid is obtained.

[0061] Step 102. Deacidification and dealcoholization:

[0062] The esterified liquid prepared in step 101 is cooled and allowed to stand for 2 hours, and then quantitatively and continuously transported to a preheated dealcoholization tower, and distilled for 3 hours under the conditions of a tower bottom temperature of 98° C., a tower top temperature of 12° C., a tower pressure of -0.077 MPa, and a reflux ratio of 340 kg / h, and a recoverable composition and crude triisobutyl phosphate are distilled out from the top and bottom of the dealcoholization tower, respectively;

[0063] Step 103. Refining:

[0064] The crude triisobutyl phosphate prepared in step 102 is quantitatively input into the primary distillation tower at a flow rate of 340 kg / hr. The primary distillation tower is a kettle-type distillation tower. During the initial distillation process of the primary distillation tower, the pressure in the primary distillation tower is -0.089 MPa, the bottom temperature is 135° C., the top temperature is 11° C., and the reflux ratio is 382 kg / h. When there is distillate at the top of the primary distillation tower, a full reflux operation is performed. After the top temperature and pressure of the bottom of the primary distillation tower remain constant, the primary top distillate is condensed, collected, stored, and analyzed for components and their corresponding contents. According to the components and contents of the primary top distillate, when the isobutanol content is higher than the preset interval value, it is refluxed to the deacidification and dealcoholization tower kettle in step 102. When the isobutanol content is lower than the preset interval value, it is transported to the next step, and then the primary bottom distillate is directly transported to the secondary distillation tower;

[0065] The secondary distillation tower is a kettle-type distillation tower. During the secondary distillation process of the secondary distillation tower, the pressure in the secondary distillation tower is -0.089MPa, the bottom temperature is 160°C, the top temperature is 125°C, and the reflux ratio is 377kg / h. When the top and bottom temperature and pressure of the distillation tower are constant, a full reflux operation is performed, and the front fraction of the secondary tower top is collected and stored and refluxed to the primary distillation tower; when the acid value of the secondary tower top distillate reaches the preset range standard value, the secondary tower top distillate is condensed and collected and stored, which is refined triisobutyl phosphate;

[0066] Step 104. Isobutanol recovery

[0067] The recyclable composition obtained in step 102 and the collected liquid at the top of the primary distillation tower obtained in step 103 are circulated in sequence through an alkali washing column and a drying column at an average flow rate of 340 kg / h for deacidification and drying. During the deacidification and drying process, the pressure in the column is -0.098 MPa and the elution temperature is 33° C. After the pH value is adjusted to 7 and the mixture is allowed to stand for 12 hours, isobutanol is recovered. The recovered isobutanol is refluxed into the reactor in step 101 and the cyclic reaction is continued until the reaction is completed. It is measured that the purity of the recovered isobutanol is 99.03%.

[0068] In summary, the flow rate of the secondary tower top distillate is 312kg / h, the acid value of the secondary tower top distillate is 0.0058mgKOH / g, the secondary tower top distillate is refined triisobutyl phosphate with a purity of 99.91%, the water content of the secondary tower top distillate is 0.0067%, the color is 2APHA, and based on the theoretical difference rate, the esterification reaction yield is 90.7%, the conversion rate of 1t of isobutanol with a purity ≥99.9% is 85.1%, and the esterification reaction time is 4.7h.

[0069] Comparative Example 1

[0070] Comparative Example 1 is a method for preparing triisobutyl phosphate commonly used in the prior art. The reaction rate is increased by a catalyst, and no micro-tubular esterification reactor is required. Conventional reactors and distillation equipment can be used for production. The process includes the following steps:

[0071] Iron tetraoxide (catalyst), isobutanol and phosphorus oxychloride were added into the reaction kettle in the mass ratio of 1:132:30, stirred and cooled to 25°C, and the reaction time was 252min under the condition of vacuum degree of -0.06MPa. After the reaction was completed, the material was transferred to the dealcoholization kettle, stirred, heated for dealcoholization, and the vacuum degree of the system was maintained at -0.07MPa. The dealcoholization time was 125min. When the dealcoholization temperature rose to 85°C, the heating was stopped, and when the temperature rose to 107°C, the vacuum was released, and the material was transferred to the neutralization kettle, stirred and cooled, and the mass The product was neutralized with 20% soda ash solution until the pH value was 7. After the neutralization was completed, 50°C hot water was added, stirred for 5 minutes, and allowed to stand for 40 minutes. The water layer was separated and the material was put into a distillation kettle for heating and distillation. The vacuum of the distillation system was maintained at 0.092MPa. The fraction above 160°C was triisobutyl phosphate, with a yield of 88.6%, a product purity of 99.6%, a water content of 0.028%, an acid value of 0.0096mg / KOH, a color of 8APHA, an isobutyl alcohol utilization rate of 81%, and an esterification reaction time of 5.5h.

[0072] It can be seen from Examples 1-3 and Comparative Example 1 that the esterification reaction time in Examples 1-3 is within 5 hours. Compared with the production process commonly used in the prior art in Comparative Example 1, the microchannel reactor is used to increase the specific surface area of ​​the fluid in the reactor, increase the reaction rate, and ensure the conversion rate of the raw materials. The utilization rate of isobutanol is higher than 83%, the yield is higher than 90%, and the product purity is higher than 99.9%. No acidic catalyst is required to be added during the esterification process, which can effectively reduce a series of side reactions generated by HCl during the esterification process. The alkali washing column is used instead of the water washing process, and the two processes of water washing and alkali neutralization can be integrated into one process, which reduces the generation of phosphorus-containing and acid-containing wastewater. The wastewater treatment cost is greatly reduced; and the excess isobutanol is recycled in the dealcoholization process; high-purity recycled isobutanol is obtained by alkali washing column treatment, the HCl and H2O contents in the recycled isobutanol are reduced, the side reactions are reduced, and the amount of by-products is reduced; the improved process technology of the present invention avoids the waste of raw materials caused by the water washing process, improves the utilization rate of raw materials, reduces production energy consumption, conforms to the green chemistry concept and national environmental protection emission standards, and compared with the conventional acid catalyst esterification method in the prior art, has the advantages of high economic benefit, energy saving and environmental protection, the reaction rate is equivalent to the catalyst esterification method, the actual operation is simple, and it is easy to promote and implement.

[0073] 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 continuous preparation process for triisobutyl phosphate, characterized in that: The following steps are involved: Step 101. Esterification: Isobutanol and phosphorus oxychloride are simultaneously introduced into the reactor at a flow ratio of 2:7-10, and esterification is performed for 3h-5h at 5-55°C to obtain an esterified liquid; Step 102. Deacidification and dealcoholization: The esterified liquid prepared in step 101 is cooled and allowed to stand for 1 h to 2 h, and then quantitatively and continuously transported to a preheated dealcoholization tower, and distilled for 2 h to 3 h under the conditions of a tower bottom temperature of 60° C. to 140° C., a tower top temperature of 5° C. to 30° C., and a tower internal pressure of (-0.01) MPa to (-0.098) MPa, to distill out a recoverable composition and crude triisobutyl phosphate from the tower top and the tower bottom, respectively; Step 103. Refining: The crude triisobutyl phosphate prepared in step 102 is transferred to a primary distillation tower, which is a kettle-type distillation tower. During the primary distillation process of the primary distillation tower, the primary tower top distillate is condensed and collected and stored, and the primary tower bottom distillate is directly transported to a secondary distillation tower; The secondary distillation tower is a kettle-type distillation tower. During the secondary distillation process of the secondary distillation tower, the front fraction at the top of the secondary tower is collected, stored and refluxed to the primary distillation tower; When the acid value of the secondary tower top distillate reaches the preset range standard value, the secondary tower top distillate is condensed and collected and stored, which is refined triisobutyl phosphate, and the acid value of the obtained product is ≤0.01mgKOH / g; Step 104. Isobutanol recovery: The recyclable composition obtained in step 102 and the collected liquid at the top of the primary distillation tower obtained in step 103 are sequentially deacidified and dried by passing through an alkali washing column and a drying column. Under the conditions of a column pressure of (-0.096) MPa-(-0.098) MPa and an elution temperature of 25°C-60°C, the pH value is adjusted to 6-8 to obtain recovered isobutanol, which is refluxed into the reactor in step 101 to continue the cyclic reaction until the reaction is completed.

2. A continuous preparation process for triisobutyl phosphate according to claim 1, characterized in that: In step 101, the reactor is a microchannel reactor, a tubular reactor, or a composite esterification reactor, and the specific surface area of ​​the fluid in the reactor is 104m 2 / m 3 -106m 2 / m 3 .

3. A continuous preparation process for triisobutyl phosphate according to claim 2, characterized in that: In step 101, the thermal conductivity of the reactor is ≥25kW / (m 2 ·K).

4. A continuous preparation process for triisobutyl phosphate according to claim 1, characterized in that: In step 101, 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 5°C-55°C.

5. A continuous preparation process for triisobutyl phosphate according to claim 1, characterized in that: In step 101, based on the theoretical yield, the conversion rate of isobutanol during the esterification reaction is ≥ 83.3%.

6. A continuous preparation process for triisobutyl phosphate according to claim 1, characterized in that: The purity of the recovered isobutanol prepared in step 104 is ≥ 99%.

7. A continuous preparation process for triisobutyl phosphate according to claim 1, characterized in that: In step 104, the filler in the alkali washing column is any one of alkalis such as sodium hydroxide, sodium carbonate, calcium oxide, and alkali metal oxides, or a mixture of more than one of them; the filler in the drying column is any one of molecular sieves, activated carbon, silica gel, caustic soda flakes, calcium oxide, sodium sulfate, and calcium chloride, or a mixture of more than one of them.

8. A continuous preparation process for triisobutyl phosphate according to claim 1, characterized in that: In step 103, during the primary distillation process of the primary distillation tower, the bottom temperature is 110°C-140°C, the top temperature is 5°C-30°C, and the primary distillation pressure is (-0.01Mpa)-(-0.099Mpa); during the secondary distillation process of the distillation tower, the bottom temperature is 150°C-160°C, the top temperature is 95°C-125°C, and the secondary distillation pressure is (-0.01Mpa)-(-0.099Mpa).

9. A continuous preparation process for triisobutyl phosphate according to claim 1, characterized in that: In step 103, the purity of the refined triisobutyl phosphate is ≥99.9%, the water content is ≤0.2%, and the color is ≤5APHA. Calculated based on the theoretical yield, the yield of the refined triisobutyl phosphate is 90%-96%.