A process for producing polyphenylene ether using a tubular reactor

Abstract

The present invention discloses a process for producing polyphenylene ether using a tubular reactor, belonging to the technical fields of polymer production and reactor design. The tubular reactor mainly comprises a liquid-phase mixer, a reactor main body and a gas-liquid separator connected in series in sequence. The outlet of the liquid-phase mixer is connected to the bottom side wall of the reactor main body. A gas inlet is connected to the bottom of the reactor main body, and a gas distributor is arranged between the gas inlet and the reactor main body. Internal components are arranged in the reactor main body. The top outlet of the reactor main body is connected to the gas-liquid separator. The tubular reactor is used for the oxidative coupling of 2,6-dimethylphenol to produce polyphenylene ether, and the obtained reaction mixture is separated to obtain a polyphenylene ether product. The present invention overcomes the problems of large internal backmixing degree, wide molecular weight distribution of the product and difficulty in realizing molecular weight regulation in an intermittent stirred tank reactor. The present invention also realizes continuous production operations of the reaction, catalyst, solvent and product separation processes, which is beneficial to industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer production and reactor design, and particularly relates to a process for producing polyphenylene ether using a tubular reactor. Background Art

[0002] Polyphenylene ether (PPO) is an engineering plastic with excellent comprehensive properties. It not only has good mechanical properties but also has outstanding properties such as low dielectric constant, low dielectric loss, low moisture absorption, high glass transition temperature, and resistance to acid and alkali corrosion. Therefore, it has broad application prospects in fields such as automotive parts, electronic devices, office equipment, coatings and additives, and photovoltaic junction boxes. In the prior art, the processes for producing polyphenylene ether all use homogeneous batch reactors. The inside of this type of reactor is in a completely mixed flow state, with a large amount of heat generated during the reaction process. The mass transfer and heat transfer effects are not ideal, and backmixing is serious, making it difficult to scale up and operate in industrial production. At the same time, since the catalyst and the product need to be separated quickly after the reaction, otherwise the polyphenylene ether produced by polymerization will further crosslink to form a three-dimensional network structure, affecting the product quality. Moreover, the batch reactor is not conducive to the continuous operation of the system after the reaction, resulting in great difficulty in the industrial application of this process. Summary of the Invention

[0003] Aiming at the technical problems existing in the background art, the purpose of the present invention is to provide a process for producing polyphenylene ether using a tubular reactor. The reactor of the present invention has a simple structure, is easy to operate, and has a large operating flexibility. It can flexibly adjust the operating conditions according to requirements to produce polyphenylene ether products with different molecular weight grades.

[0004] The purpose of the present invention is achieved in the following way:

[0005] The present invention provides a process for producing polyphenylene ether using a tubular reactor. The tubular reactor mainly includes a liquid-phase mixer 5, a reactor main body 1, and a gas-liquid separator 8 connected in series through pipelines in sequence. The inlets of the liquid-phase mixer 5 are respectively connected to a reaction liquid inlet 4 and a catalyst inlet 11; the reactor main body 1 is vertical, the outlet of the liquid-phase mixer 5 is connected to the bottom side wall of the reactor main body 1 through a pipeline, a gas inlet 6 is connected to the bottom of the reactor main body 1, a gas distributor 7 is arranged on the cross-section between the gas inlet 6 and the reactor main body 1, internal components 2 are arranged inside the reactor main body 1, a heat exchange jacket 3 is arranged outside the shell of the reactor main body 1 or / and heat exchange tubes are arranged inside the reactor main body 1 to control the temperature inside the reactor. The top outlet of the reactor main body 1 is connected to the gas-liquid separator 8 through a pipeline. A gas outlet 9 is arranged at the top end of the gas-liquid separator 8, and a liquid outlet 10 is arranged at the bottom end.

[0006] It mainly includes the following steps:

[0007] (1) The organic solvent dissolved with phenol monomers is introduced into the liquid-phase mixer 5 through the reaction liquid inlet 4, and is fully mixed with the organic solvent containing the catalyst introduced through the catalyst inlet 11 in the liquid-phase mixer 5 to obtain a mixed solution of the reaction raw material and the catalyst;

[0008] (2) The mixed solution of the reaction raw material and the catalyst enters the reactor main body 1 from the bottom of the reactor main body 1, and fully contacts and reacts with the oxygen-containing mixed gas in the form of bubbles dispersed by the gas distributor 7 and introduced through the gas inlet 6, and moves upward along the axis of the reactor main body 1; the heat exchange jacket 3 or / and the heat exchange tube maintain the reaction temperature in the reactor main body 1, and the internal components 2 in the reactor main body 1 increase the turbulence degree of the liquid phase and control the bubble size, increasing the mixing effect between the gas-liquid two phases;

[0009] (3) The mixture after the reaction enters the gas-liquid separator 8 from the top of the reactor main body 1. After gas-liquid separation, the gas is discharged from the gas outlet 9 at the top of the gas-liquid separator 8, and the mixed liquid flows out from the liquid-phase outlet 10 at the bottom of the gas-liquid separator 8 and is separated and purified to obtain polyphenylene ether.

[0010] Based on the above technical solution, further, the molecular weight of the polyphenylene ether product is controlled by adjusting the amount of the mixed gas introduced at the bottom of the reactor or the oxygen concentration and the residence time of the material in the reactor.

[0011] Based on the above technical solution, further, the structure of the phenol monomer described in step (1) is shown in formula (Ⅰ),

[0012]

[0013] In formula (Ⅰ), R 1 and R 2 are each independently hydrogen, C 1-4 alkyl, haloalkyl, aminoalkyl or alkoxy, and R 3 is hydrogen or halogen.

[0014] Based on the above technical solution, further, the organic solvent described in step (1) is one or a mixture of two or more of toluene, xylene, benzene, nitrobenzene, dichloromethane, chloroform, pyridine.

[0015] Based on the above technical solution, further, the concentration of the phenol monomer in the organic solvent dissolved with the phenol monomer in step (1) is 10 - 300 g / L.

[0016] Based on the above technical solution, further, the catalyst described in step (1) is a complex of cuprous chloride and organic amine, and the concentration of the catalyst in the organic solvent containing the catalyst is 0.1 - 20 g / L.

[0017] Based on the above technical solution, further, the feed flow ratio of the organic solvent dissolved with phenol monomers to the organic solvent containing the catalyst in step (1) is 1:5 to 5:1.

[0018] Based on the above technical solution, further, in step (1), the reaction temperature in the reactor main body 1 is 20 - 150 °C, the reaction pressure is 0.01 - 10 MPa, and the liquid phase residence time is 0.1 - 24 hours.

[0019] Based on the above technical solution, further, in step (2), the oxygen-containing mixed gas is an oxygen / nitrogen mixed gas, the oxygen concentration is 5% - 100%, and the introduced mixed gas is introduced from the bottom of the reactor main body 1, or is introduced at different heights of the reactor main body 1 in a certain proportion.

[0020] Based on the above technical solution, further, in step (2), the flow rate of the oxygen-containing mixed gas is 0.2 - 5000 L / min.

[0021] Based on the above technical solution, further, the specific process of the separation and purification in step (3) is: adding the reaction mixture into a large amount of methanol solvent, filtering, washing, and vacuum drying to obtain a solid product, that is, the polyphenylene ether product.

[0022] Based on the above technical solution, further, the height of the reactor main body 1 is 0.5 - 50 m, and the inner diameter is 10 - 6000 mm.

[0023] Based on the above technical solution, further, the internal component 2 is one or a combination of two or more of a perforated plate, a Raschig ring, a Pall ring, and a θ ring.

[0024] Based on the above technical solution, further, the reactor main body 1 is a single reaction unit or is composed of 2 - 100 reaction units connected in series. The inner diameter and length of each reaction unit are adjusted accordingly according to the reaction process, and each reaction unit is arranged coaxially or side by side.

[0025] The beneficial effects of the present invention compared with the prior art are as follows:

[0026] The present invention uses a tubular reactor for the multiphase polymerization to produce polyphenylene ether, which can overcome the problems of serious backmixing in the stirred tank reactor, wide molecular weight distribution of the polyphenylene ether product, and difficulty in molecular weight regulation. At the same time, using a tubular reactor can also realize the continuous production operation of the reaction and the separation processes of the catalyst, solvent, and product, which is beneficial to engineering scale-up and industrial production operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments will be briefly introduced below.

[0028] Figure 1 It is the tubular reactor in Example 1; In the figure: 1 - reactor main body; 2 - internal component; 3 - heat exchange jacket; 4 - reaction liquid inlet; 5 - liquid mixer; 6 - gas inlet; 7 - gas distributor; 8 - gas-liquid separator; 9 - gas outlet; 10 - liquid outlet; 11 - catalyst inlet. Specific implementation manners

[0029] The present invention will be described in detail below in conjunction with embodiments, but the implementation manners of the present invention are not limited thereto. Obviously, the embodiments described below are only partial embodiments of the present invention. For those skilled in the art, without creative efforts, obtaining other similar embodiments all fall within the protection scope of the present invention.

[0030] Example 1

[0031] This example provides a process for preparing polyphenylene ether using a tubular reactor. The total length of the tubular reactor used in this process is 2 m, and the inner diameter of the reactor is 50 mm. The tubular reactor mainly includes a liquid mixer 5, a reactor main body 1, and a gas-liquid separator 8 connected in series in sequence through pipelines. The inlets of the liquid mixer 5 are respectively communicated with the reaction liquid inlet 4 and the catalyst inlet 11; the reactor main body 1 is vertical. The outlet of the liquid mixer 5 is connected to the bottom side wall of the reactor main body 1 through a pipeline. A gas inlet 6 is connected to the bottom of the reactor main body 1. A gas distributor 7 is arranged on the cross-section between the gas inlet 6 and the reactor main body 1. An internal component 2 is arranged in the reactor main body 1. The internal component is a stainless steel Pall ring. A heat exchange jacket 3 is arranged on the outer side of the shell of the reactor main body 1 to control the temperature in the reactor. The top outlet of the reactor main body 1 is connected to the gas-liquid separator 8 through a pipeline. A gas outlet 9 is arranged at the top end of the gas-liquid separator 8, and a liquid outlet 10 is arranged at the bottom end.

[0032] Using the above reactor, the preparation process mainly includes the following steps:

[0033] Dissolve 840 g of 2,6-dimethylphenol in 3.75 kg of toluene solvent. After complete dissolution, introduce it into the liquid-phase mixer 5 at a flow rate of 17.3 mL / min. At the same time, introduce a mixed solution of cuprous chloride and organic amine complex catalyst and toluene solvent into the liquid-phase mixer 5 at a flow rate of 35.0 mL / min, where the feed rate of the raw materials is 4.7 g / min. Control the reaction temperature at 30 °C. Pass a mixture of oxygen / nitrogen at the bottom of the reactor, with an oxygen concentration of 75% and an oxygen flow rate of 1.2 L / min. The residence time is about 0.5 hours. After passing through the gas-liquid separator at the reactor outlet for gas-liquid separation, the gas phase is discharged into the atmosphere through the gas outlet 9 after condensation and absorption, and the liquid phase is collected through the liquid outlet 10 to obtain the reactants. Drop the reactants into a large amount of methanol, and after filtration, washing, and vacuum drying to constant weight, a solid product is obtained, that is, a polyphenylene ether product with a yield of 78.57%, a number-average molecular weight of 13000, a weight-average molecular weight of 27000, and a molecular weight distribution of 2.1.

[0034] Example 2 - 5

[0035] According to the scheme of Example 1, adjust the feed composition of the gas, and adjust the intake amounts of oxygen and nitrogen. Do not adjust other conditions. The specific adjustments are shown in Table 1 below.

[0036] Table 1 Intake amounts of oxygen and nitrogen and product parameters for Examples 2 - 5

[0037]

[0038]

[0039] Examples 6 - 8

[0040] According to the scheme of Example 1, use pure oxygen as the reaction gas. The specific adjustments are shown in Table 2 below.

[0041] Table 2 Intake amount of oxygen and product parameters for Examples 6 - 8

[0042] Example 6 7 8 Oxygen flow rate (ml / min) 900 1200 1500 Number-average molecular weight 14000 16000 19000 Weight-average molecular weight 27000 29000 36000 Molecular weight distribution 1.9 1.8 1.9 Yield (%) 78.79 80.45 82.58

[0043] Examples 9 - 12

[0044] Replace the reactor with an 8 m tubular reactor, keep the inner diameter of the reactor unchanged, use pure oxygen as the oxidant, keep the feed ratio of each reaction substance unchanged, adjust the feed rate to adjust the residence time, and control the reaction temperature at 30 °C. The specific adjustments are shown in Table 3 below.

[0045] Table 3 Intake amount of oxygen, residence time, and product parameters for Examples 9 - 12

[0046] Example 9 10 11 12 Residence time (h) 0.5 0.5 1 2 Oxygen flow rate (ml / min) 2800 3200 3600 4000 Number-average molecular weight 38000 45000 53000 63000 Weight-average molecular weight 129000 144000 179000 145000 Molecular weight distribution 1.8 1.8 2.0 2.3 Yield (%) 85.69 89.56 91.35 91.54

[0047] Examples 13 - 15

[0048] Replace the reactor with a tubular reactor of 8 m, keeping the inner diameter of the reactor unchanged. Use pure oxygen as the oxidant, with a total oxygen flow rate of 3600 ml / min, a residence time of 1 h, and adjust the reaction temperature to be controlled within 25 - 50 °C. The specific adjustments are shown in Table 4 below.

[0049] Table 4 Reaction temperatures and product parameters of Examples 13 - 15

[0050] Example 13 14 15 Reaction temperature (°C) 25 40 50 Number-average molecular weight 35000 58000 60000 Weight-average molecular weight 63000 197000 228000 Molecular weight distribution 1.8 3.4 3.8 Yield (%) 85.57 89.87 91.54

[0051] Examples 16 - 18

[0052] Replace the reactor with a tubular reactor of 4 m, keeping the inner diameter of the reactor unchanged. Use pure oxygen as the oxidant, with a total oxygen flow rate of 3000 ml / min, a residence time of 0.5 h, and adjust the reaction temperature to be controlled at 30 °C. Adjust the air intake position, and supply a certain amount of oxygen at the positions of 0, 1, 2, and 3 m of the reactor respectively, with a total oxygen flow rate of 3000 ml / min. The specific adjustments are shown in Table 5 below.

[0053] Table 5 Air intake amounts at different positions and product parameters of Examples 16 - 18

[0054] Example 16 17 18 Intake air volume at 0 m position (ml / min) 3000 1500 1000 Intake air volume at 1 m position (ml / min) 0 0 1000 Intake air volume at 2 m position (ml / min) 0 1500 500 Intake air volume at 3 m position (ml / min) 0 0 500 Number-average molecular weight 40000 39000 39000 Weight-average molecular weight 100000 94000 82000 Molecular weight distribution 2.5 2.4 2.1 Yield (%) 88.95 88.65 88.73

[0055] Examples 19 - 23

[0056] Replace the reactor with a tubular reactor of 16 m, keeping the inner diameter of the reactor unchanged. Use pure oxygen as the oxidant, with a total oxygen flow rate of 4000 ml / min, control the reaction temperature at 30 °C, keep the feeding ratio of each reaction substance unchanged, and adjust the feeding amount to adjust the residence time. The specific adjustments are shown in Table 6 below.

[0057] Table 6 Different residence times and product parameters of Examples 19 - 23

[0058]

[0059]

[0060] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for producing polyphenylene ether using a tubular reactor, characterized in that, the tubular reactor mainly comprises a liquid-phase mixer, a reactor main body and a gas-liquid separator connected in series in sequence through pipelines. The inlet of the liquid-phase mixer is respectively communicated with a reaction liquid inlet and a catalyst inlet; the reactor main body is in a vertical shape. The outlet of the liquid-phase mixer is connected with the bottom side wall of the reactor main body through a pipeline. A gas inlet is connected to the bottom of the reactor main body. A gas distributor is arranged on the cross-section between the gas inlet and the reactor main body. Inner components are arranged in the reactor main body. A heat exchange jacket is arranged on the outer side of the shell of the reactor main or / and heat exchange tubes are arranged in the reactor main body. The top outlet of the reactor main body is connected with the gas-liquid separator through a pipeline. A gas outlet is arranged at the top end of the gas-liquid separator, and a liquid outlet is arranged at the bottom end; the process comprises the following steps: (1) An organic solvent dissolved with a phenol monomer is introduced into the liquid-phase mixer through the reaction liquid inlet, and is fully mixed with the organic solvent containing a catalyst introduced through the catalyst inlet in the liquid-phase mixer to obtain a mixed solution of a reaction raw material and a catalyst; (2) The mixed solution of the reaction raw material and the catalyst enters the reactor main body from the bottom of the reactor main body, and fully contacts and reacts with an oxygen-containing mixed gas in the form of bubbles dispersed by the gas distributor and introduced through the gas inlet, and moves upward along the axis of the reactor main body; the heat exchange jacket or / and the heat exchange tubes maintain the reaction temperature in the reactor main body. The inner components in the reactor main body increase the turbulence degree of the liquid phase and control the bubble size, and increase the mixing effect between the gas-liquid two phases; (3) The reacted mixture enters the gas-liquid separator from the top of the reactor main body. After gas-liquid separation, the gas is discharged from the gas outlet at the top of the gas-liquid separator, and the mixed liquid flows out from the liquid-phase outlet at the bottom of the gas-liquid separator and is separated and purified to obtain polyphenylene ether; in step (1), the concentration of the phenol monomer in the organic solvent dissolved with the phenol monomer is 10 - 300 g / L; the catalyst is a complex of cuprous chloride and an organic amine, and the concentration of the catalyst in the organic solvent containing the catalyst is 0.1 - 20 g / L; the feed volume flow ratio of the organic solvent dissolved with the phenol monomer to the organic solvent containing the catalyst is 1:5 to 5:1; in step (1), the reaction temperature in the reactor main body is 20 - 150 °C, the reaction pressure is 0.01 - 10 MPa, and the liquid-phase residence time is 0.1 - 24 hours; the inner components are one or a combination of two or more of a perforated plate, a Raschig ring, a Pall ring, and a θ ring.

2. The process according to claim 1, characterized in that, the molecular weight of the polyphenylene ether product is controlled by adjusting the amount of the mixed gas introduced into the bottom of the reactor, the oxygen concentration, and the residence time of the material in the reactor.

3. The process according to claim 1, characterized in that, the structure of the phenol monomer in step (1) is as shown in formula (Ⅰ), R in formula (I) 1 and R 2 are each independently hydrogen, C 1-4 alkyl, haloalkyl, aminoalkyl or alkoxy, and R 3 is hydrogen or halogen.

4. The process according to claim 1, characterized in that, the organic solvent in step (1) is one or a mixture of two or more of toluene, xylene, benzene, nitrobenzene, dichloromethane, chloroform, and pyridine.

5. According to the process described in claim 1, characterized in that, in step (2), the oxygen-containing mixed gas is an oxygen / nitrogen mixed gas, the oxygen concentration is 5%-100%, and the introduced mixed gas is introduced from the bottom of the reactor main body, or is introduced at different heights of the reactor main body in a certain proportion; the flow rate of the oxygen-containing mixed gas is 0.2-5000 L / min.

6. According to the process described in claim 1, characterized in that, the height of the reactor main body is 0.5-50 m, and the inner diameter is 10-6000 mm.

7. According to the process described in claim 1, characterized in that, the reactor main body is a single reaction unit or is composed of 2-100 reaction units connected in series, and the inner diameter and length of each reaction unit are adjusted accordingly according to the reaction process, and each reaction unit is arranged coaxially or side by side.

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