Preparation method of anti-aging agent 6PPD
By using filler separation technology and evaporating gas phase preheating raw materials in the production of anti-aging agent 6PPD, the problems of poor separation effect, high energy consumption and low purity in the prior art are solved, and a more efficient and lower energy consumption production process is achieved.
Patent Information
- Application Number
- CN202311432347.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-31
- Publication Date
- 2025-05-02
AI Technical Summary
In the prior art, the production method of anti-aging agent 6PPD has problems such as poor gravity settlement separation effect, high production energy consumption and low product purity.
The condensed hydrogenation reaction liquid is processed using filler separation technology to significantly improve the separation effect of hydrogen, and the evaporated gas phase preheated raw materials to reduce energy consumption and improve reaction fluidity, thereby improving product purity.
The production process is significantly simplified through filler separation, reduced energy consumption, and improved the purity of the anti-aging agent 6PPD, solving the problems of poor separation effect, high energy consumption and low purity in the prior art.
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Figure CN119912342A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of fine chemicals, and in particular to a method for preparing an antioxidant 6PPD. Background Art
[0002] Antioxidant 6PPD is suitable for natural rubber and synthetic rubber. Its application scope includes pneumatic tire parts, solid tires, conveyor belts, hoses, tapes, cables, automobile buffer brackets, rubber joints and general rubber industrial products.
[0003] The current production method of antioxidant 6PPD is as follows Figure 1 As shown: methyl isobutyl ketone, p-aminodiphenylamine and hydrogen undergo condensation hydrogenation reaction under the action of a catalyst to obtain a condensation hydrogenation reaction liquid. The condensation hydrogenation reaction liquid undergoes a primary separation in a primary gravity settling separator to obtain a primary separation gas phase and a primary separation liquid phase.
[0004] The primary separation gas phase enters the secondary gravity sedimentation separator for secondary separation to obtain a secondary separation gas phase and a secondary separation liquid phase. The secondary separation gas phase is circulating hydrogen, which is compressed by a compressor and returned to the condensation hydrogenation reaction. The secondary separation liquid phase is separated to obtain an organic phase and an aqueous phase. Among them, the organic phase is the recovered methyl isobutyl ketone, which is returned to the condensation hydrogenation reaction again. The aqueous phase is treated with azeotropic distillation to meet the emission standards and then discharged.
[0005] The primary separated liquid phase is successively treated by falling film evaporation and rotary film evaporation to obtain the antioxidant 6PPD. The steam separated in the falling film evaporation and rotary film evaporation process is condensed and then returned to the condensation hydrogenation reaction.
[0006] The production method of the above-mentioned antioxidant 6PPD mainly has the following defects: 1. The separation principle of the gravity sedimentation separator is to utilize the weight difference between liquid and gas. The separation effect of this separation method is poor, and the first-stage separation gas phase contains hydrogen and a large amount of unreacted methyl isobutyl ketone. The hydrogen containing more methyl isobutyl ketone cannot enter the hydrogen compressor for compression. This is because the hydrogen contains liquid methyl isobutyl ketone, which will increase the load of the compressor, and in severe cases, it may cause the liquid to enter the compressor cylinder and damage the suction valve plate. The density of liquid methyl isobutyl ketone is hundreds of times that of gaseous hydrogen, so the momentum of liquid during flow is much larger than that of gas, and the impact generated is also much larger, which can cause the damage of the compression force-bearing parts in a very short time, so the first-stage separation gas phase needs to further separate methyl isobutyl ketone before returning to the condensation hydrogenation reaction. 2. The heat in the steam separated from the primary separation liquid phase during the falling film evaporation and rotary film evaporation process was not effectively utilized, resulting in an energy consumption of about 420-440 kgce / t per ton of antioxidant 6PPD; 3. The raw materials for the condensation hydrogenation reaction have high viscosity and poor fluidity, and local overheating is prone to occur during the reaction process, resulting in low selectivity of the catalyst and more side reactions. The purity of the antioxidant 6PPD needs to be further improved.
[0007] Therefore, there is an urgent need to provide a method for preparing an antioxidant 6PPD with a simple production process, low production energy consumption and high product purity. Summary of the invention
[0008] The purpose of the present invention is to overcome the problems of poor separation effect of hydrogen in condensation hydrogenation reaction liquid, high production energy consumption and low product purity in the prior art, and to provide a method for preparing an antioxidant 6PPD.
[0009] In order to achieve the above object, the present invention provides a method for preparing an antioxidant 6PPD, wherein the method comprises the following steps:
[0010] (1) preheating a raw material containing methyl isobutyl ketone, p-aminodiphenylamine and hydrogen and contacting the raw material with a catalyst to carry out a condensation hydrogenation reaction to obtain a condensation hydrogenation reaction liquid;
[0011] (2) performing packing separation on the condensation hydrogenation reaction liquid to obtain circulating hydrogen and liquid phase materials; wherein the circulating hydrogen is returned to step (1) for recycling;
[0012] (3) subjecting the liquid phase material to falling film evaporation to obtain an evaporated gas phase I and a crude antioxidant 6PPD product;
[0013] (4) subjecting the crude antioxidant 6PPD to rotary film evaporation to obtain an evaporated gas phase II and the antioxidant 6PPD;
[0014] (5) Returning the evaporated gas phase I and / or evaporated gas phase II to step (1) for preheating the raw material.
[0015] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:
[0016] 1) The preparation method of the antioxidant 6PPD provided in the present invention utilizes a filler to separate the condensation hydrogenation reaction liquid, which can significantly improve the separation effect of hydrogen, and can directly return the recycled hydrogen to step (1) for recycling, which can greatly simplify the production process;
[0017] 2) The preparation method of the antioxidant 6PPD provided in the present invention utilizes the evaporation gas phase I from the falling film evaporation and / or the evaporation gas phase II from the rotary film evaporation to preheat the raw materials containing methyl isobutyl ketone, p-aminodiphenylamine and hydrogen. On the one hand, the heat of the materials can be comprehensively utilized to significantly reduce the energy consumption of the preparation method of the antioxidant 6PPD. On the other hand, the viscosity of the condensation hydrogenation reaction raw materials can be reduced, the fluidity of the condensation hydrogenation reaction raw materials can be increased, and the phenomenon of local overheating during the reaction can be avoided, which is helpful to improve the selectivity of the catalyst, reduce the occurrence of side reactions, and improve the purity of the antioxidant 6PPD. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is a production process flow chart of antioxidant 6PPD in the prior art;
[0019] Figure 2 The present invention provides a production process flow chart of the antioxidant 6PPD. DETAILED DESCRIPTION
[0020] The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
[0021] The present invention provides a method for preparing an antioxidant 6PPD, wherein the method comprises the following steps:
[0022] (1) preheating a raw material containing methyl isobutyl ketone, p-aminodiphenylamine and hydrogen and contacting the raw material with a catalyst to carry out a condensation hydrogenation reaction to obtain a condensation hydrogenation reaction liquid;
[0023] (2) performing packing separation on the condensation hydrogenation reaction liquid to obtain circulating hydrogen and liquid phase materials; wherein the circulating hydrogen is returned to step (1) for recycling;
[0024] (3) subjecting the liquid phase material to falling film evaporation to obtain an evaporated gas phase I and a crude antioxidant 6PPD product;
[0025] (4) subjecting the crude antioxidant 6PPD to rotary film evaporation to obtain an evaporated gas phase II and the antioxidant 6PPD;
[0026] (5) Returning the evaporated gas phase I and / or evaporated gas phase II to step (1) for preheating the raw material.
[0027] In step (1):
[0028] In one embodiment of the present invention, the temperature of the raw material after preheating is 68-98°C, preferably 80-95°C.
[0029] In one embodiment of the present invention, the molar ratio of methyl isobutyl ketone to p-aminodiphenylamine is 1:2-8, preferably 1:4-5.
[0030] In one embodiment of the present invention, the catalyst is a copper-based catalyst or a noble metal catalyst known in the art.
[0031] In one embodiment of the present invention, the operating conditions of the condensation hydrogenation reaction include: the catalyst mass space velocity is 0.2-0.6h -1 , preferably 0.4-0.5h -1 ; The reaction hydrogen-oil volume ratio is 100-200, preferably 160-185; the hydrogen partial pressure is 1-4.5MPa, preferably 2.5-3.5MPa; the reaction temperature is 100-200°C, preferably 120-160°C; the reaction time is 1.5-5h, preferably 2.5-3.5h.
[0032] Wherein, the reaction hydrogen-to-oil ratio refers to the volume ratio of hydrogen to (the sum of methyl isobutyl ketone and p-aminodiphenylamine). Unless otherwise specified, the pressures mentioned in the present invention are all gauge pressures. In the present invention, methyl isobutyl ketone, p-aminodiphenylamine and hydrogen undergo condensation hydrogenation reaction, p-aminodiphenylamine can be basically completely reacted, and the main components of the condensation hydrogenation reaction liquid are antioxidant 6PPD (N-(1,3-dimethylbutyl)-N'-phenyl p-phenylenediamine), unreacted methyl isobutyl ketone and hydrogen, and generated water.
[0033] In step (2):
[0034] In one embodiment of the present invention, the filler separation is performed in a filler separator, wherein the filler in the filler separator is a polyhedral hollow sphere filler.
[0035] The polyhedral hollow ball filler is a sphere composed of two hemispheres, each hemisphere is composed of several half-fan-shaped blades, and the upper and lower blades are staggered and arranged radially along the central axis. Among them, there can be 6-12 half-fan-shaped blades on each hemisphere, preferably 6 half-fan-shaped blades. The advantage of this filler is that it is easy to completely accumulate in the filler layer, but it will not cause bridging and pore effects, and the specific surface area of this filler is large, which can fully solve the gas-liquid exchange, thereby significantly improving the gas-liquid separation efficiency.
[0036] In one embodiment of the present invention, the polyhedral hollow sphere filler is made of stainless steel, has a diameter of 25-100 mm, and a specific surface area of 100-500 m 2 / m 3 , the stacking number is 7000-25000n / m, and the stacking density is 550-980kg / m 3 .
[0037] In one embodiment of the present invention, the operating conditions for the packing separation include: the packing space velocity is 0.5-1.5h -1 , preferably 1-1.2h -1 ; The separation temperature is 100-200°C, preferably 120-160°C; the separation pressure is 1-4MPa, preferably 2-3MPa.
[0038] In one embodiment of the present invention, the content of hydrogen in the circulating hydrogen is ≥ 99v%, preferably 99.8-99.95v%.
[0039] Among them, in the present invention, the filler separation can significantly improve the separation effect of hydrogen in the condensation hydrogenation reaction liquid, so that the volume content of hydrogen in the separated circulating hydrogen is as high as 99%, and the volume content of methyl isobutyl ketone is less than 0.1%. Therefore, there is no need to separate methyl isobutyl ketone from the circulating hydrogen, and the circulating hydrogen can be directly compressed and returned to step (1) for recycling, which can simplify the process and shorten the production process of the antioxidant 6PPD.
[0040] In step (3):
[0041] In one embodiment of the present invention, the operating conditions of the falling film evaporation include: evaporation temperature of 120-200°C, preferably 130-180°C; absolute pressure of 1-20 kPa, preferably 3-10 kPa. In the present invention, the feed flow rate of the liquid phase material can be 2.0-3.0 kg / h, preferably 2.1-2.5 kg / h.
[0042] In step (4):
[0043] In one embodiment of the present invention, the operating conditions of the rotary film evaporation include: evaporation temperature of 140-210°C, preferably 150-190°C; absolute pressure of 1-15 kPa, preferably 2-8 kPa. In the present invention, the feed flow rate of the antioxidant 6PPD crude product can be 1.2-2.0 kg / h, preferably 1.4-1.8 kg / h.
[0044] In step (5):
[0045] In one embodiment of the present invention, in order to accurately control the feed ratio of the raw materials, the preheating is indirect heat exchange; wherein the evaporated gas phase I and / or evaporated gas phase II is returned to step (1) to perform indirect heat exchange with the raw materials to obtain a mixed liquid containing methyl isobutyl ketone and waste water.
[0046] Among them, in the present invention, the evaporation gas phase I from falling film evaporation and the evaporation gas phase II from rotary film evaporation are high-temperature steam. The energy consumption of the preparation method of the antioxidant 6PPD can be significantly reduced by preheating the raw materials using the heat in the evaporation gas phase I and / or the evaporation gas phase II.
[0047] In one embodiment of the present invention, the mixed liquid containing methyl isobutyl ketone and waste water is subjected to liquid separation treatment to obtain recovered methyl isobutyl ketone and waste water; wherein the recovered methyl isobutyl ketone is returned to step (1) for recycling.
[0048] In the present invention, the evaporated gas phase I and the evaporated gas phase II each independently include unreacted methyl isobutyl ketone and water generated during the reaction. Since methyl isobutyl ketone is slightly soluble in water, the property of methyl isobutyl ketone being slightly soluble in water can be utilized to obtain recovered methyl isobutyl ketone and waste water through liquid separation. The waste water also contains a small amount of methyl isobutyl ketone, and the waste water can be subjected to azeotropic distillation treatment to further separate a small amount of methyl isobutyl ketone in the waste water to obtain purified water that meets the discharge standards.
[0049] The present invention will be described in detail by way of examples below. The catalyst is a NZF type antioxidant catalyst with a specification of Ф5×(4.5-5.5) mm, purchased from Nanjing Zunlong New Materials Technology Co., Ltd.
[0050] Example 1
[0051] (1) Methyl isobutyl ketone, p-aminodiphenylamine and hydrogen are mixed in a mixer to obtain a raw material containing methyl isobutyl ketone, p-aminodiphenylamine and hydrogen; the mixed raw material is preheated to 92° C. in a heat exchanger and then introduced into a reactor to contact with a catalyst for condensation hydrogenation reaction to obtain a condensation hydrogenation reaction liquid; wherein the molar ratio of methyl isobutyl ketone to p-aminodiphenylamine is 1:4, and the mass space velocity of the catalyst is 0.45 h -1, the reaction hydrogen-to-oil volume ratio is 175, the hydrogen partial pressure is 2.8MPa, the reaction temperature is 150°C, and the reaction time is 3.0h;
[0052] (2) introducing the condensation hydrogenation reaction liquid into a packing separator for packing separation to obtain circulating hydrogen and liquid phase materials, and returning the obtained circulating hydrogen to the reactor for recycling; wherein the packing in the packing separator is a stainless steel polyhedral hollow sphere packing (particle size 38 mm, specific surface area 250 m 2 / m 3 , the stacking number is 22500n / m, and the stacking density is 745kg / m 3 ), the mass space velocity of the packing is 1.0h -1 , the separation temperature is 150℃, and the separation pressure is 2.8MPa;
[0053] (3) introducing the above liquid phase material into a falling film evaporator, the mass flow rate of the liquid phase material is 2.3 kg / h, and performing falling film evaporation at an evaporation temperature of 160° C. and an absolute pressure of 8 kPa to obtain an evaporated gas phase I and a crude antioxidant 6PPD;
[0054] (4) introducing the crude antioxidant 6PPD into a rotary film evaporator at a mass flow rate of 1.6 kg / h, and performing rotary film evaporation at an evaporation temperature of 180° C. and an absolute pressure of 5 kPa to obtain an evaporated gas phase II and the antioxidant 6PPD;
[0055] (5) introducing the evaporated gas phase I and the evaporated gas phase II into a heat exchanger to exchange heat with the raw material to obtain a mixed solution containing methyl isobutyl ketone and wastewater; allowing the obtained mixed solution containing methyl isobutyl ketone and wastewater to stand at 25° C. for 1 hour and then separating the liquids to obtain recovered methyl isobutyl ketone and wastewater; wherein the recovered methyl isobutyl ketone is returned to the reactor for recycling, and the wastewater is subjected to azeotropic distillation treatment to further separate a small amount of methyl isobutyl ketone in the wastewater and then discharge it.
[0056] The residual amount of RT base in the condensation hydrogenation reaction liquid is 0.01wt%, the organic impurity content generated by the reaction is 0.12wt%, the hydrogen content in the circulating hydrogen is 99.95v%, and the methyl isobutyl ketone is 0.05v%. The purity of the antioxidant 6PPD is 98.7%, and the product energy consumption is 350kgce / t.
[0057] Example 2
[0058] Compared with Example 1, the difference is that the raw material is preheated to 85°C in the heat exchanger, and the mass space velocity of the filler is 1.1h -1 The separation temperature is 130℃ and the separation pressure is 2.4MPa. The particle size of the stainless steel multi-faceted hollow ball filler in the filler separator is 50mm and the specific surface area is 200m2 / m 3 The stacking number is 11250n / m, and the stacking density is 680kg / m 3 .
[0059] Among them, the residual amount of RT base in the condensation hydrogenation reaction liquid is 0.02wt%, the content of organic impurities generated by the reaction is 0.14wt%; the content of hydrogen in the circulating hydrogen is 99.92v%, methyl isobutyl ketone is 0.08v%, the purity of the antioxidant 6PPD is 98.5%, and the product energy consumption is 346kgce / t.
[0060] Example 3
[0061] Compared with Example 1, the difference is that the preheating is preheated to 78°C in the heat exchanger, and the mass space velocity of the filler is 1.3h -1 The separation temperature is 180℃ and the separation pressure is 1.5MPa. The particle size of the stainless steel multi-faceted hollow ball filler in the packing separator is 100mm and the specific surface area is 105m 2 / m 3 , the stacking number is 7000n / m, and the stacking density is 580kg / m 3 .
[0062] Among them, the residual amount of RT base in the condensation hydrogenation reaction liquid is 0.05wt%, the content of organic impurities generated by the reaction is 0.17wt%; the content of hydrogen in the circulating hydrogen is 99.90v%, methyl isobutyl ketone is 0.10v%, the purity of the antioxidant 6PPD is 98.2%, and the product energy consumption is 340kgce / t.
[0063] Comparative Example 1
[0064] (1) Methyl isobutyl ketone, p-aminodiphenylamine and hydrogen are mixed in a mixer and introduced into a reactor to contact with a catalyst for condensation hydrogenation reaction to obtain a condensation hydrogenation reaction liquid; wherein the molar ratio of methyl isobutyl ketone to p-aminodiphenylamine is 1:4, and the mass space velocity of the catalyst is 0.45 h -1 , the reaction hydrogen-to-oil volume ratio is 175, the hydrogen partial pressure is 2.8MPa, the reaction temperature is 150°C, and the reaction time is 3.0h;
[0065] (2) introducing the condensation hydrogenation reaction liquid into a primary gravity sedimentation separator, and performing primary separation at 150° C. and 2.8 MPa to obtain a primary separation gas phase and a primary separation liquid phase;
[0066] (3) introducing the primary separated gas phase into a secondary gravity sedimentation separator, and performing secondary separation at 25° C. and 2.6 MPa to obtain a secondary separated gas phase and a secondary separated liquid phase; wherein the secondary separated gas phase is circulating hydrogen, which is compressed by a compressor and returned to the reactor for recycling;
[0067] (4) The secondary separated liquid phase is allowed to stand at 25° C. for 1 hour and then separated to obtain an organic phase and an aqueous phase; the organic phase is the recovered methyl isobutyl ketone, which is returned to the reactor for recycling; the aqueous phase is subjected to azeotropic distillation to further separate a small amount of methyl isobutyl ketone in the aqueous phase and then discharged;
[0068] (5) introducing the primary separated liquid phase into a falling film evaporator, and performing falling film evaporation at an evaporation temperature of 160° C. and an absolute pressure of 8 kPa to obtain an evaporated gas phase I and a crude antioxidant 6PPD;
[0069] (6) introducing the above-mentioned crude antioxidant 6PPD into a rotary film evaporator, and performing rotary film evaporation at an evaporation temperature of 180° C. and an absolute pressure of 5 kPa to obtain an evaporated gas phase II and antioxidant 6PPD;
[0070] (7) The evaporated gas phase I and the evaporated gas phase II are cooled to 35° C. by a condenser and then returned to the reactor for recycling.
[0071] Among them, the residual amount of RT base in the condensation hydrogenation reaction liquid is 0.12wt%, and the content of organic impurities generated by the reaction is 0.45wt%; the primary separation gas phase contains 65v% hydrogen, 30v% methyl isobutyl ketone, 2.5v% water and 2.5v% other impurities; the content of hydrogen in the circulating hydrogen is 99.7v%, and 0.3v% methyl isobutyl ketone; the purity of the antioxidant 6PPD is 97.8%, and the product energy consumption is 432kgce / t.
[0072] By comparing Example 1 and Comparative Example 1, it can be seen that in the present invention, by preheating the raw materials and using fillers for separation, not only can the separation effect of hydrogen be significantly improved, the circulating hydrogen can be directly returned to step (1) for recycling, greatly simplifying the production process, but also the conversion rate of aminodiphenylamine can be increased, the occurrence of side reactions can be reduced, and the purity of the antioxidant 6PPD can be improved.
[0073] Comparative Example 2
[0074] (1) Methyl isobutyl ketone, p-aminodiphenylamine and hydrogen are mixed in a mixer, preheated to 92° C. by external steam, and then introduced into a reactor to contact with a catalyst for condensation hydrogenation reaction to obtain a condensation hydrogenation reaction liquid; wherein the molar ratio of methyl isobutyl ketone to p-aminodiphenylamine is 1:4, and the mass space velocity of the catalyst is 0.45 h -1 , the reaction hydrogen-to-oil volume ratio is 175, the hydrogen partial pressure is 2.8MPa, the reaction temperature is 150°C, and the reaction time is 3.0h;
[0075] (2) introducing the condensation hydrogenation reaction liquid into a primary gravity sedimentation separator, and performing primary separation at 150° C. and 2.8 MPa to obtain a primary separation gas phase and a primary separation liquid phase;
[0076] (3) introducing the primary separated gas phase into a secondary gravity sedimentation separator, and performing secondary separation at 25° C. and 2.6 MPa to obtain a secondary separated gas phase and a secondary separated liquid phase; wherein the secondary separated gas phase is circulating hydrogen, which is compressed by a compressor and returned to the reactor for recycling;
[0077] (4) The secondary separated liquid phase is allowed to stand at 25° C. for 1.0 h and then separated to obtain an organic phase and an aqueous phase; the organic phase is the recovered methyl isobutyl ketone, which is returned to the reactor for recycling; the aqueous phase is subjected to azeotropic distillation to further separate a small amount of methyl isobutyl ketone in the aqueous phase and then discharged;
[0078] (5) introducing the primary separated liquid phase into a falling film evaporator, and performing falling film evaporation at an evaporation temperature of 160° C. and an absolute pressure of 8 kPa to obtain an evaporated gas phase I and a crude antioxidant 6PPD;
[0079] (6) introducing the above-mentioned crude antioxidant 6PPD into a rotary film evaporator, and performing rotary film evaporation at an evaporation temperature of 180° C. and an absolute pressure of 5 kPa to obtain an evaporated gas phase II and antioxidant 6PPD;
[0080] (7) The evaporated gas phase I and the evaporated gas phase II are cooled to 35° C. by a condenser and then returned to the reactor for recycling.
[0081] Among them, the residual amount of RT base in the condensation hydrogenation reaction liquid is 0.015wt%, and the content of organic impurities generated by the reaction is 0.13wt%; the primary separation gas phase contains 63v% hydrogen, 32v% methyl isobutyl ketone, 2.6v% water and 2.4% other impurities; the content of hydrogen in the circulating hydrogen is 99.6v%, and 0.4v% methyl isobutyl ketone; the purity of the antioxidant 6PPD is 98.5%, and the product energy consumption is 508kgce / t.
[0082] Among them, by comparing Example 1 and Comparative Example 2, it can be seen that compared with gravity separation, the use of filler separation can improve the separation effect of hydrogen in the condensation hydrogenation reaction liquid, shorten the preparation process of the antioxidant 6PPD, and reduce the energy consumption of the product.
[0083] Comparative Example 3
[0084] (1) Methyl isobutyl ketone, p-aminodiphenylamine and hydrogen are mixed in a mixer and introduced into a reactor to contact with a catalyst for condensation hydrogenation reaction to obtain a condensation hydrogenation reaction liquid; wherein the molar ratio of methyl isobutyl ketone to p-aminodiphenylamine is 1:4, and the mass space velocity of the catalyst is 0.45 h-1 , the reaction hydrogen-to-oil volume ratio is 175, the hydrogen partial pressure is 2.8MPa, the reaction temperature is 150°C, and the reaction time is 3.0h;
[0085] (2) introducing the condensation hydrogenation reaction liquid into a packing separator for packing separation to obtain circulating hydrogen and liquid phase materials, and returning the obtained circulating hydrogen to the reactor for recycling; wherein the packing in the packing separator is a stainless steel polyhedral hollow sphere packing (particle size 38 mm, specific surface area 250 m 2 / m 3 , the stacking number is 22500n / m, and the stacking density is 745kg / m 3 ), the mass space velocity of the packing is 1.0h -1 , the separation temperature is 150℃, and the separation pressure is 2.8MPa;
[0086] (3) introducing the above liquid phase material into a falling film evaporator, and performing falling film evaporation at an evaporation temperature of 160° C. and an absolute pressure of 8 kPa to obtain an evaporated gas phase I and a crude antioxidant 6PPD;
[0087] (4) introducing the above-mentioned crude antioxidant 6PPD into a rotary film evaporator, and performing rotary film evaporation at an evaporation temperature of 180° C. and an absolute pressure of 5 kPa to obtain an evaporated gas phase II and antioxidant 6PPD;
[0088] (5) The evaporated gas phase I and the evaporated gas phase II are cooled to 35° C. by a condenser and then returned to the reactor for recycling.
[0089] The residual amount of RT base in the condensation hydrogenation reaction liquid is 0.11wt%, the organic impurity content generated by the reaction is 0.43wt%, the hydrogen content in the circulating hydrogen is 99.91v%, and the methyl isobutyl ketone is 0.09v%. The purity of the antioxidant 6PPD is 98.1%, and the product energy consumption is 435kgce / t.
[0090] Among them, by comparing Example 1 and Comparative Example 3, it can be known that preheating the raw materials can, on the one hand, improve the conversion rate of the reaction and reduce the occurrence of side reactions, and on the other hand, can further reduce the reaction energy consumption.
[0091] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.
Claims
1. A method for preparing an antioxidant 6PPD, characterized in that the method comprises the following steps: (1) preheating a raw material containing methyl isobutyl ketone, p-aminodiphenylamine and hydrogen and contacting the raw material with a catalyst to carry out a condensation hydrogenation reaction to obtain a condensation hydrogenation reaction liquid; (2) performing packing separation on the condensation hydrogenation reaction liquid to obtain circulating hydrogen and liquid phase materials; wherein the circulating hydrogen is returned to step (1) for recycling; (3) subjecting the liquid phase material to falling film evaporation to obtain an evaporated gas phase I and a crude antioxidant 6PPD product; (4) subjecting the crude antioxidant 6PPD to rotary film evaporation to obtain an evaporated gas phase II and the antioxidant 6PPD; (5) Returning the evaporated gas phase I and / or evaporated gas phase II to step (1) for preheating the raw material.
2. The preparation method according to claim 1, wherein The temperature of the raw materials after preheating is 68-98°C, preferably 80-95°C.
3. The preparation method according to claim 1 or 2, wherein The molar ratio of methyl isobutyl ketone to p-aminodiphenylamine is 1:2-8, preferably 1:4-5; Preferably, the operating conditions of the condensation hydrogenation reaction include: the catalyst mass space velocity is 0.2-0.6h -1 , preferably 0.4-0.5h -1 ; The reaction hydrogen-oil volume ratio is 100-200, preferably 160-185; the hydrogen partial pressure is 1-4.5MPa, preferably 2.5-3.5MPa; the reaction temperature is 100-200°C, preferably 120-160°C; the reaction time is 1.5-5h, preferably 2.5-3.5h.
4. The preparation method according to any one of claims 1 to 3, wherein The filler separation is carried out in a filler separator, and the filler in the filler separator is a multi-faceted hollow ball filler.
5. The preparation method according to claim 4, wherein: The polyhedral hollow ball filler is made of stainless steel, with a diameter of 25-100 mm and a specific surface area of 100-500 m 2 / m 3 , the stacking number is 7000-25000n / m, and the stacking density is 550-980kg / m 3 .
6. The preparation method according to any one of claims 1 to 5, wherein: The operating conditions for the packing separation include: the packing space velocity is 0.5-1.5h -1 , preferably 1-1.2h -1 ; The separation temperature is 100-200°C, preferably 120-160°C; the separation pressure is 1-4MPa, preferably 2-3MPa.
7. The preparation method according to any one of claims 1 to 6, wherein: The operating conditions of the falling film evaporation include: an evaporation temperature of 120-200° C., preferably 130-180° C.; and an absolute pressure of 1-20 kPa, preferably 3-10 kPa.
8. The preparation method according to any one of claims 1 to 7, wherein: The operating conditions of the rotary film evaporation include an evaporation temperature of 140-210° C., preferably 150-190° C.; and an absolute pressure of 1-15 kPa, preferably 2-8 kPa.
9. The preparation method according to any one of claims 1 to 8, wherein: The preheating is an indirect heat exchange, wherein the evaporated gas phase I and / or evaporated gas phase II is returned to step (1) to perform indirect heat exchange with the raw material to obtain a mixed liquid containing methyl isobutyl ketone and waste water.
10. The preparation method according to claim 9, wherein: The mixed liquid is separated to obtain recovered methyl isobutyl ketone and waste water; wherein the recovered methyl isobutyl ketone is returned to step (1) for recycling.