Method for preparing m-xylylenediamine, bubble generating component, bubble generator and three-phase bubbling bed reaction device

Abstract

The invention discloses a method for preparing m-xylylenediamine, a bubble generation component, a bubble generator and a three-phase bubbling bed reaction device.The problems that in the prior art, gas distribution is not uniform, the bubble generator is prone to being blocked, and the product quality is low are mainly solved, and the method comprises the steps that m-xylylenediamine is fed into a liquid-phase feeding section of the three-phase bubbling bed reaction device; hydrogen is fed through the bubble generator, so that the hydrogen is in contact with the m-xylylenediamine to generate the m-xylylenediamine. According to the invention, the conversion rate of the catalyst can be improved, the service life and regeneration period of the catalyst can be prolonged, and stable operation of the device is facilitated.

Description

Technical Field

[0001] The present invention relates to a bubble generating member, a bubble generator, a three-phase bubbling bed reaction device, its application and a method for preparing m-xylenediamine. Background Art

[0002] m-Xylenediamine (MXDA) is an important monomer for synthesizing high-end materials, and it mainly has three major applications: one is used as a curing agent for low-temperature, low-toxic (LD50 1.0 g / kg), low-viscosity epoxy resin, with a fast curing speed at room temperature, good heat resistance, water resistance and chemical resistance; the second is to synthesize polyhexamethylene adipamide m-xylenediamine (nylon MXD6), which has high high-temperature strength and elasticity, a high deformation temperature, a low thermal expansion rate, and good barrier properties; the third is to synthesize m-xylylene diisocyanate (XDI) polyurethane resin, which has a high film hardness, low toxicity and excellent yellowing resistance. In addition, it can also be used to synthesize high-end electronic curing agents such as 1,3-diaminomethylcyclohexane. The global demand for MXDA exceeds 70,000 - 80,000 tons / year, and is monopolized by Mitsubishi Gas, BASF and Showa Denko. In China, with the strong demand for MXD6, the demand for MXDA exceeds 40,000 tons / year (the actual output < 0.4 million tons / year).

[0003] At present, foreign MXDA production technologies all adopt the continuous hydrogenation method of isophthalonitrile (IPN). The main technical bottlenecks are the regulation of the selectivity and stability of the fixed-bed catalyst for the complex reaction network. At the same time, because it involves ammonia substances, higher requirements are put forward for the design of the entire reaction process route and the selection of equipment design. The continuous production and research and development of MXDA in China are still in its infancy. Only the batch kettle reaction has achieved small-scale industrial transformation, and the products can only meet low-end curing agents. In the fields of high-end electronic curing agents and high-end barrier nylons, due to the lack of high-quality MXDA synthesis technology, the production capacity and purity (> 99.5%) are far from meeting the market demand.

[0004] The reaction equations are as follows:

[0005] Main reaction:

[0006]

[0007] Main side reactions:

[0008] (1) Insufficient hydrogenation: Generation of intermediate imines (A, B, C), which are extremely active and prone to polymerization.

[0009]

[0010] (2) Excessive hydrogenation: Generation of 3-methylbenzylamine, m-xylene, etc.

[0011]

[0012] (3) Condensation and deamination: The amino group attacks the imine as a nucleophile, generating high-boiling substances such as secondary amines, tertiary amines, and crosslinked amines, which affect the reaction selectivity and yield. The high-boiling substances adsorb on the catalyst surface, further reducing the adsorption of imine and potentially leading to catalyst deactivation.

[0013] As can be seen from the above, due to the many side reactions and exothermic nature of the preparation of m-xylylenediamine by hydrogenation of isophthalonitrile, if the gas-liquid distribution in the reactor is uneven and the reaction heat cannot be withdrawn in time, it will not only lead to an increase in side reactions, but more seriously, the generated heavy components will directly adhere to the surface of the catalyst, resulting in a decrease in catalyst activity. This affects the service life of the catalyst as well as the quality and yield of the product.

[0014] CN101774928A discloses a method for preparing m-xylylenediamine. This method uses a fixed-bed hydrogenation reactor, dissolves isophthalonitrile in an organic amide solvent, and then enters a bed containing a catalyst in the form of a solution to react with hydrogen under certain reaction conditions to obtain m-xylylenediamine. This method uses a fixed-bed reactor and has high requirements for the uniformity of the gas-liquid two-phase distribution. Once the distribution is uneven, the phenomenon of uneven flow is likely to occur in the catalyst bed, resulting in too large a temperature difference in the bed, which is not conducive to reaction control. In addition, the heavy components generated by side reactions gradually accumulate, and the active sites of the catalyst are gradually covered, and the service life and performance of the catalyst will gradually decline.

[0015] CN101337894A discloses a method for continuously hydrogenating m-xylylenediamine in a stirred tank, which performs multiphase hydrogenation using isophthalonitrile as a raw material. In this method, in a hydrogenation reactor containing at least two series-connected stirred tanks, a mixture of isophthalonitrile and a solvent and hydrogen are brought into contact with a granular solid catalyst for continuous hydrogenation reaction; the reaction liquid flowing out of the last-stage stirred tank and the solid catalyst continuously enter a separator for solid-liquid separation, and the separated reaction liquid is separated to obtain the target product; the separated catalyst is recycled after regeneration and returned to the hydrogenation reaction kettle. This method uses a stirred-tank reactor, which has a complex structure, not only has high requirements for the processing and manufacturing ability of the stirrer, but also is not conducive to large-scale production. In addition, the catalyst needs to participate in the solid-liquid separation operation subsequently, which not only makes the process flow more complex, but also puts higher requirements on the strength and life of the catalyst.

[0016] CN114671769A discloses a process for the continuous production of m-xylylenediamine. In this method, isophthalonitrile, a solvent, and a reaction auxiliary are brought into contact with a granular solid catalyst under the driving force of hydrogen pressure to carry out a three-phase hydrogenation reaction. Then, it enters a solid-liquid separator, and the separated liquid is the target product after separation. The catalyst after solid-liquid separation is recycled. After its activity decreases, it is activated and then recycled. In this method, a separator is installed in the reactor, and thus it is divided into a separation zone and a stationary zone. The mixed solution after the reaction returns to the reactor to participate in the reaction after solid-liquid separation. Not only is the energy consumption large and the production efficiency low, but the solid-liquid separation process used has a high degree of catalyst wear, and the design pressures of equipment such as the reactor, separator, and solid-liquid separator all need to be kept consistent with the reactor, resulting in large equipment investment and high subsequent maintenance costs.

[0017] In order to reduce side reactions in the production process of m-xylylenediamine, reduce the generation amount of by-products, increase the product yield of m-xylylenediamine, improve production efficiency at the same time, ensure the safety of the process, and achieve the long-term stable operation of equipment and catalysts, it is necessary to strictly control the range of the reactor temperature and pressure. The key is to ensure the full and uniform contact of the gas, liquid, and solid phases. Summary of the Invention

[0018] The purpose of the present invention is to solve the problems existing in the prior art, such as the gas-phase distributor in the reaction device is prone to blockage, the gas-phase feed flow rate is prone to fluctuate, resulting in a reduction in the expected service life of the catalyst, a decline in product quality and yield, an increase in energy consumption, and poor equipment safety and process stability. Provided are a bubble generating member, a bubble generator, a three-phase bubble column reaction device and its application, and a method for preparing m-xylylenediamine, which have the advantages of high mass transfer efficiency, uniform temperature distribution, increased conversion rate of the catalyst, extended service life and regeneration cycle of the catalyst, strong adaptability to different working conditions, good safety, and stable process operation.

[0019] To achieve the above purpose, in the first aspect of the present invention, a bubble generating member is provided, and the bubble generating member includes:

[0020] A housing, a cavity is formed inside the housing, a plurality of exhaust holes communicating with the cavity are formed on the housing, and a flow stabilizer is arranged in the cavity, and the flow stabilizer can avoid fluctuations in the discharge flow rate of the gas phase.

[0021] In the second aspect of the present invention, a bubble generator is provided, and the bubble generator includes a distribution plate and a plurality of the bubble generating members of the present invention arranged on the distribution plate; preferably, a plurality of through holes are provided on the distribution plate, and each through hole corresponds to one of the bubble generating members and is communicated with the gas-phase inlet of the corresponding bubble generating member.

[0022] The third aspect of the present invention provides a three-phase bubbling bed reaction device, which sequentially includes a gas-phase feeding section, a liquid-phase feeding section, and a solid-phase section from bottom to top. Among them, a bubble generator of the present invention is provided between the gas-phase feeding section and the liquid-phase feeding section.

[0023] The present invention provides the application of the three-phase bubbling bed reaction device of the present invention in chemical absorption, oxidation reaction, and hydrogenation reaction, preferably in the preparation of m-xylylenediamine.

[0024] The fourth aspect of the present invention provides a method for preparing m-xylylenediamine. This method uses the three-phase bubbling bed reaction device of the present invention. Among them, isophthalonitrile is fed into the liquid-phase feeding section, and hydrogen is fed through the bubble generator, so that hydrogen contacts with isophthalonitrile to generate m-xylylenediamine.

[0025] The main technical problem to be solved by the present invention is the problems existing in the prior art, such as the reduction of the expected service life of the catalyst, the decline of product quality and yield, the increase of energy consumption, and the poor safety and process stability of the equipment caused by the easy fluctuation of the gas-phase feeding flow rate. On the one hand, a bubble generating member is disclosed, which has the advantages of strong adaptability to different working conditions, good safety and process operation stability; on the other hand, a three-phase bubbling bed reaction device is provided, which can increase the throughput, simplify the operation process of the reaction device, facilitate installation and maintenance, can well guarantee the product quality and yield, and realizes the long-term stable operation of the production device. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the bubble generating member for explaining the embodiments of the present invention;

[0027] Figure 2 is a schematic structural diagram of the bubble generator for explaining the embodiments of the present invention;

[0028] Figure 3 is a schematic structural diagram of the three-phase bubbling bed reaction device for explaining the embodiments of the present invention;

[0029] Figure 4 is Figure 3 the schematic structural diagram of the gas-phase feeding pipe in

[0030] Figure 5 is a schematic diagram of the reaction device in the prior art in the comparative example.

[0031] Description of the Reference Numerals

[0032] 1 Material outlet; 2 Upper head; 3 Pressure grid; 4 Upper layer of coarse porcelain balls; 5 Upper layer of fine porcelain balls; 6 Catalyst bed; 7 Lower layer of fine porcelain balls; 8 Lower layer of coarse porcelain balls; 9 Support grid; 10 Bubble generator; 11 Gas-phase feed pipe; 12 Drain port; 13 Buffer section; 14 Ultrasonic transducer; 15 Liquid-phase feed pipe; 16 Agent discharge port; 17 Limit post; 101 Upper protrusion; 102 Bubble generating member; 104 Exhaust hole; 103 Piston; 105 Lower protrusion; 106 Distribution plate. Specific embodiments

[0033] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustration and explanation of the present invention, and are not intended to limit the present invention.

[0034] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0035] In the invention, unless otherwise stated, the orientation words such as "upper, lower, top, bottom" are usually in the direction shown in the drawings or in the vertical, perpendicular or gravitational direction for describing the relative positional relationship of each component; "inside, outside" usually refers to inside and outside the cavity relative to the inner cavity or radially inside and outside relative to the center of the circle.

[0036] The main technical problems to be solved by the present invention are the problems existing in the prior art, such as the reduction of the expected service life of the catalyst, the decline of product quality and yield, the increase of energy consumption, and the poor safety and process stability of the equipment caused by the easy fluctuation of the gas-phase feed flow rate. A bubble generating member is disclosed, which has the advantages of strong adaptability to different flow rates, good safety and process operation stability.

[0037] On the one hand, the present invention provides a bubble generating member, as Figure 1 shown, the bubble generating member 102 includes:

[0038] A housing, an inner cavity is formed inside the housing, a plurality of exhaust holes 104 communicating with the cavity are formed on the housing, and a flow stabilizing member is arranged in the cavity, and the flow stabilizing member can avoid the fluctuation of the discharge flow rate of the gas phase.

[0039] In some embodiments of the present invention, the bottom opening of the shell is formed as a gas phase inlet, a plurality of exhaust holes 104 are distributed on the peripheral wall of the shell, and the flow stabilizer is configured as a piston 103 that can slide axially along the cavity; in this way, even when the feed flow rate of the gas phase suddenly increases, the piston 103 is pushed up to expose more exhaust holes 104 for exhaust.

[0040] In order to make the gas phase more evenly distributed in the space, in some embodiments of the present invention, it is preferred that a plurality of exhaust hole rings which are spaced apart in sequence along the axial direction are provided on the peripheral wall of the shell (the distance between the topmost exhaust hole ring and the top of the cavity is greater than the height of the piston 103), and each exhaust hole ring includes a plurality of exhaust holes which are arranged in a ring shape and spaced apart along the circumferential direction.

[0041] It is understandable that, in order to prevent the piston from falling out of the cavity or getting stuck at the top of the cavity, in some embodiments of the present invention, the bubble generating member 102 preferably includes a piston stopper, and the piston stopper includes an upper piston stopper and a lower piston stopper, wherein, Figure 1 As shown, in order to prevent the piston 103 from slipping out of the cavity, the piston lower limit member can be a lower protrusion 105 arranged on the bottom opening of the shell. In order to prevent the piston 103 from being stuck on the top of the cavity, the piston upper limit member can be an upper protrusion 101 arranged on the top wall of the cavity. The upper protrusion 101 and the lower protrusion 105 can be arranged in a ring shape. Furthermore, a spring can be installed between the top wall of the cavity and the piston 3, and the upper end of the spring is connected to the top wall of the cavity, and the lower end is connected to the piston 103.

[0042] The present invention further discloses a bubble generator based on the above disclosure. Figure 2 As shown, the bubble generator 10 includes a distribution plate 106 and a plurality of bubble generating components 102 of the present invention uniformly arranged on the distribution plate 106 ; preferably, a plurality of through holes are arranged on the distribution plate 106 , each through hole corresponds to a bubble generating component 102 and is connected to the gas phase inlet of the corresponding bubble generating component 102 .

[0043] In some embodiments of the present invention, the center distance between two adjacent bubble generating components 102 on the distribution plate 106 is 50-100 mm, the distance between two adjacent exhaust hole rings on each bubble generating component 102 is 5-20 mm, the diameter of the cavity of each bubble generating component 102 is 50-100 mm, and the total opening area of ​​the shell of each bubble generating component 102 is 10%-40%, preferably 15%-25% of the cross-sectional area of ​​the gas phase feed pipe. In this way, it has good safety and process operation stability advantages.

[0044] The present invention discloses a three-phase bubbling bed reaction device based on the above disclosure, such as Figure 3As shown in the figure, the cavity of the three-phase bubbling bed reactor device sequentially includes a gas-phase feeding section, a liquid-phase feeding section, and a solid-phase section from bottom to top. Among them, a bubble generator 10 of the present invention is arranged between the gas-phase feeding section and the liquid-phase feeding section. In this way, a plurality of through holes of the bubble generator are located in the gas-phase feeding section, and the exhaust holes of the bubble generator are located in the liquid-phase feeding section.

[0045] In some embodiments of the present invention, the three-phase bubbling bed reactor device includes a clogging clearing member for clearing the clogging of the bubble generator 10, which can solve the problems of uneven gas distribution, easy clogging of the bubble generator, and low product quality existing in the prior art.

[0046] To achieve a better clogging clearing effect, in some embodiments of the present invention, preferably, there are a plurality of clogging clearing members. The plurality of clogging clearing members are uniformly arranged along the circumferential direction outside the three-phase bubbling bed reactor device and are connected to the distribution plate 106 of the bubble generator 10. More preferably, the number of the plurality of clogging clearing members ≥ 4; for example, when the diameter of the reaction cavity is 500 - 1600 mm, it is preferably 4 - 6, and when the diameter of the reaction cavity is greater than 2000 mm, it is preferably 8 - 12.

[0047] In some embodiments of the present invention, the clogging clearing member includes a vibrating member with a vibrating function. More preferably, the clogging clearing member includes an ultrasonic transducer 14 connected to the distribution plate 106 of the bubble generator 10. Thus, while clearing the clogging, the clogging material can also be heated. There are no special requirements for the ultrasonic transducer in the present invention, as long as it can achieve the clogging clearing function, and the present invention will not elaborate on this.

[0048] In some embodiments of the present invention, a pre-distribution member is arranged in the gas-phase feeding section for pre-distributing the gas fed into the cavity of the three-phase bubbling bed reactor device, so as to have the advantage of more uniform gas distribution.

[0049] In some embodiments of the present invention, as Figure 4 shown, preferably, the pre-distribution member includes a gas-phase feeding pipe 11. The gas-phase feeding pipe 11 extends into the gas-phase feeding section and is bent towards the bottom of the cavity to form a bent portion, and the end of the bent portion forms a reduced-diameter section that gradually tapers downward.

[0050] In some embodiments of the present invention, more preferably, the diameter of the small end of the reduced-diameter section is 1 / 4 to 1 / 2 of the diameter of the gas-phase feed pipe, further preferably 1 / 4 to 1 / 3, and the length of the reduced-diameter section is 1 to 2 times the diameter of the gas-phase feed pipe, further preferably 1.5 to 2.5 times; more preferably, a plurality of distribution holes are uniformly formed in the peripheral wall of the reduced-diameter section, and the types of the distribution holes include but are not limited to oblong holes, rhombus-shaped holes, and circular holes, preferably oblong holes, and the sum of the areas of the plurality of distribution holes is 15% to 40% of the cross-sectional area of the gas-phase feed pipe, further preferably 15% to 25%. Using the foregoing values enables more sufficient gas-liquid mixing. In the present invention, the diameter of the gas-phase feed pipe refers to the diameter of the large end of the reduced-diameter section, and the cross-sectional area of the gas-phase feed pipe 11 refers to the cross-sectional area of the large end of the reduced-diameter section.

[0051] In some embodiments of the present invention, the gas-phase feed section has a buffer portion 13, and the pre-distribution member is installed in the buffer portion 13, such as Figure 3 shown, the buffer portion 13 is provided as a space with a diameter smaller than the diameter of the cavity body.

[0052] In some embodiments of the present invention, the three-phase bubbling bed reactor is arranged as Figure 1 shown, the diameters of the solid-phase section, the liquid-phase feed section, and a part of the gas-phase feed section are the same. Preferably, the diameter of the cavity located in the buffer portion 13 is 20% to 50% of the diameter of the cavity located in the solid-phase section, more preferably 20% to 40%; preferably, the height-diameter ratio of the cavity located in the buffer portion 13 is 0.8 to 1.5, more preferably 1 to 1.5; the height-diameter ratio of the three-phase bubbling bed reactor is 5 to 12. Using the foregoing values enables more sufficient gas-liquid mixing. In the present invention, the diameter in the height-diameter ratio of the three-phase bubbling bed reactor refers to the main diameter of the cavity, that is, the diameters of the foregoing solid-phase section and the liquid-phase feed section.

[0053] In some embodiments of the present invention, as Figure 3 shown, a material outlet 1 communicating with the cavity is provided at the top end of the upper head 2 of the three-phase bubbling bed reactor. The solid-phase section sequentially includes a pressure grid 3, an upper layer of coarse porcelain balls 4, an upper layer of fine porcelain balls 5, a catalyst bed 6, a lower layer of fine porcelain balls 7, a lower layer of coarse porcelain balls 8, and a support grid 9 from top to bottom. Among them, a catalyst discharging port 16 is provided on the cavity where the lower layer of coarse porcelain balls 8 is located. Below the support grid 9 are sequentially a liquid-phase feed section communicating with the liquid-phase feed pipe 15, a bubble generator 10 disclosed in the present invention, a gas-phase feed section, and a gas-phase gas feed pipe 11 provided in the buffer portion 13 of the gas-phase feed section. A drain port 12 is further provided at the bottom end of the buffer portion 13.

[0054] In some embodiments of the present invention, preferably, the vertical height between the bubble generator 10 and the lower layer of coarse porcelain balls 8 is 300 to 800 mm, more preferably 400 to 600 mm; thereby, more sufficient gas-liquid mixing is achieved.

[0055] It is understandable that when the reaction proceeds, the catalyst bed 6 will expand in the height direction. To ensure production safety, in some embodiments of the present invention, it is preferred that the three-phase bubbling bed reaction device is provided with a floating limit member, which can allow the catalyst bed 6 to float by 5%-10% of the height of the catalyst bed 6. As Figure 3 shown, the floating limit member includes 4-8 limit columns 17. The lower end of each limit column 17 is connected to the pressure grid, and the upper end is connected to the cavity wall of the three-phase bubbling bed reaction device.

[0056] The three-phase bubbling bed reaction device of the present invention solves the problems of poor operation flexibility (such as sudden increase in feed pressure), uneven gas phase distribution, unqualified quality and yield of reaction products, decline in the expected service life of the catalyst, and poor equipment safety and process stability of the previous reaction devices; it improves the processing capacity of the three-phase bubbling bed reaction device, simplifies the operation process of the reaction device, and is convenient for installation and maintenance. It gives full play to the characteristics of small floor area, large processing capacity, and good heat exchange effect of the bubbling bed reaction device, thus well ensuring the product quality and yield, realizing the long-term stable operation of the production device, and achieving good technical effects.

[0057] The present invention discloses the application of the three-phase bubbling bed reaction device of the present invention in chemical absorption, oxidation reaction and hydrogenation reaction, preferably in the preparation of m-xylenediamine.

[0058] On the basis of the foregoing disclosure, the present invention discloses a method for preparing m-xylenediamine. This method uses the three-phase bubbling bed reaction device of the present invention. Among them, isophthalonitrile is fed into the liquid phase feed section, and hydrogen is fed into the buffer section 13 through the gas phase feed pipe 11 and discharged through the bubble generator 10, so that hydrogen contacts with isophthalonitrile to generate m-xylenediamine.

[0059] In some embodiments of the present invention, the contact conditions include: the reaction temperature is 60-90 °C, the pressure is 6-10 MPa, and the mass space velocity of the raw material is 0-4 h -1 .

[0060] In some embodiments of the present invention, the mass ratio of hydrogen to isophthalonitrile is 5-20.

[0061] In some embodiments of the present invention, an ultrasonic transducer 14 is used to clear the blockage of the bubble generator, and the power of the ultrasonic transducer 14 Among them,

[0062] P - the power of the ultrasonic generator, kw;

[0063] f - the frequency of the ultrasonic generator, Hz;

[0064] S—the cross-sectional area of the bubble generator (i.e., the cross-sectional area of the distribution plate 106), m 2 ;

[0065] Q—the liquid-phase feed rate, kg / s;

[0066] η—the liquid-phase viscosity, kg / (m·s);

[0067] h—the overall height of the bubble generator, m.

[0068] In the present invention, there are no special requirements for other conditions in the preparation of m-xylylenediamine from hydrogen and isophthalonitrile. Conventional selections can be made in the process of preparing m-xylylenediamine from hydrogen and isophthalonitrile. For example, the catalyst can be the catalyst disclosed in the applicant's prior application CN113398933A, and the present invention will not elaborate on this.

[0069] The method of the present invention mainly solves the problems existing in the prior art, such as poor operation flexibility of the previous reaction device, uneven distribution of hydrogen, easy blockage of the bubble generator by the isophthalonitrile raw material, and low quality of the produced m-xylylenediamine product. It has the advantages of improving the conversion rate of the catalyst, prolonging the service life and regeneration cycle of the catalyst, and being beneficial to the stable operation of the device.

[0070] The advantages of the present invention will be illustrated by the following examples, but the present invention is not limited thereto.

[0071] The following examples use Figures 1 - 4 the three-phase bubble column reactor shown. The top of the upper head 2 of the three-phase bubble column reactor is provided with a material outlet 1 communicating with the cavity. The solid phase section successively includes a pressure grid 3, an upper layer of coarse porcelain balls 4, an upper layer of fine porcelain balls 5, a catalyst bed 6, a lower layer of fine porcelain balls 7, a lower layer of coarse porcelain balls 8, and a support grid 9 from top to bottom. Among them, a catalyst discharging port 16 is opened on the cavity of the lower layer of coarse porcelain balls 8. Below the support grid 9 are successively a liquid-phase feeding section communicating with the liquid-phase feeding pipe 15, a bubble generator 10, a gas-phase feeding section, and a gas-phase feeding pipe 11 arranged in the buffer section 13 of the gas-phase feeding section. A drain port 12 is also opened at the bottom of the buffer section 13; 4 limiting columns 17, with the lower end of each limiting column connected to the pressure grid and the upper end connected to the cavity wall of the three-phase bubble column reactor.

[0072] The bubble generator 10 includes a distribution plate 106 and a plurality of bubble generating members 102 provided on the distribution plate 106. The thickness of the distribution plate 106 is 10% of the height of the bubble generating member. A plurality of through holes are provided on the distribution plate 106. Each through hole corresponds to a bubble generating member 102 and is communicated with the gas phase inlet of the corresponding bubble generating member 102. The bubble generating member 102 includes: a housing, a cavity is formed inside the housing, the bottom end opening of the housing is formed as the gas phase inlet, an upper protrusion 101 is provided on the top wall of the cavity, a lower protrusion 105 is provided on the bottom end opening, a piston 103 is provided between the upper protrusion and the lower protrusion of the cavity, and a plurality of exhaust hole rings are provided on the peripheral wall of the housing at intervals along the axial direction. Each exhaust hole ring includes a plurality of exhaust holes arranged at intervals in a circumferential direction in a ring shape.

[0073] It should be noted that the catalyst used in the following examples and comparative examples is the catalyst prepared in Example 1 of CN113398933A.

[0074] Example 1

[0075] The gas phase feed pipe 11 of the three-phase bubble column reactor is horizontally extended into the buffer part 13 of the gas phase feed section and is bent towards the bottom of the cavity to form a bent part. The end of the bent part is formed as a reduced diameter section that tapers downward. A plurality of distribution holes are provided on the peripheral wall of the reduced diameter section; an ultrasonic transducer 14 connected to the bubble generator 10 is provided outside the three-phase bubble column reactor.

[0076] The main body diameter of the cavity of the three-phase bubble column reactor is 1000 mm, and the height is 5000 mm. The main body diameter of the gas phase feed pipe 11 is 200 mm. The diameter of the small end of the reduced diameter section of the gas phase feed pipe is 100 mm, the length of the reduced diameter section is 200 mm, and slotted holes are provided on the pipe wall of the reduced diameter section, and the opening area accounts for 19.25% of the cross-sectional area of the gas phase feed pipe. The diameter of the cavity of the buffer part 13 is 400 mm, the height is 600 mm, and the vertical height between the bubble generator 10 and the lower layer of coarse porcelain balls 8 is 600 mm;

[0077] 8 exhaust hole rings are provided on the housing of each bubble generating member 102 in the bubble generator 10. The distance between two adjacent exhaust hole rings on each bubble generating member 102 is 5 mm. The diameter of the cavity is 50 mm, the height is 100 mm. The total opening area of the housing of each bubble generating member 102 is 20% of the cross-sectional area of the gas phase feed pipe 11, and the center distance between two adjacent bubble generating members 102 on the distribution plate 106 is 75 mm.

[0078] Hydrogen enters the buffer section through the reduced-diameter section of the gas-phase feed pipe 11 for pre-distribution, and then passes upward through the bubble generator 10 and fully contacts with isophthalonitrile fed through the phase feed pipe 15. Bubbles are formed under the shearing action and continue to diffuse upward. After the gas-liquid mixture enters the catalyst bed, a gas-liquid-solid three-phase hydrogenation reaction occurs, and the reaction products are discharged through the top material outlet. After operating for a period of time, some fine pores in the bubble generator are blocked. The ultrasonic transducer 14 is turned on to clean the blockage of the bubble generator 10. Among them, the frequency f of the ultrasonic transducer 14 is 20,000 Hz, the liquid-phase feed rate Q is 1 kg / s, and the ultrasonic power P is 0.15 kW.

[0079] The reaction operating temperature is 75 °C, the operating pressure is 7 MPa, and the raw material mass space velocity is 2 h -1 , and the mass ratio of hydrogen to isophthalonitrile is 8.

[0080] After analysis, the results of the final product show that the conversion rate of isophthalonitrile is 99.9%, and the selectivity is 99.3%.

[0081] Example 2

[0082] Differing from Example 1: The main body diameter of the cavity of the three-phase bubble column reactor is 1000 mm, and the height is 8000 mm. The main body diameter of the gas-phase feed pipe 11 is 200 mm, the diameter of the small end of the reduced-diameter section of the gas-phase feed pipe is 50 mm, the length of the reduced-diameter section is 300 mm, and the reduced-diameter section of the pipe wall is provided with slotted holes, and the opening area accounts for 16% of the cross-sectional area of the gas-phase feed pipe. The diameter of the cavity of the buffer section 13 is 200 mm, and the height is 300 mm;

[0083] On each bubble generating member 102 of the bubble generator 10, 8 exhaust hole rings are opened on the shell. The distance between two adjacent exhaust hole rings on each bubble generating member 102 is 20 mm. The diameter of the cavity is 80 mm, and the height is 120 mm. The total opening area of the shell of each bubble generating member 102 is 16% of the cross-sectional area of the gas-phase feed pipe 11. The center distance between two adjacent bubble generating members 102 on the distribution plate 106 is 100 mm.

[0084] The frequency f of the ultrasonic transducer 14 is 20,000 Hz, the liquid-phase feed rate Q is 1 kg / s, and the ultrasonic power P is 0.15 kW. The reaction operating temperature is 75 °C, the operating pressure is 7 MPa, and the raw material mass space velocity is 2 h -1 , and the mass ratio of hydrogen to isophthalonitrile is 5.

[0085] After analysis, the results of the final product show that the conversion rate of isophthalonitrile is 99.8%, and the selectivity is 99.7%; the service life and regeneration period of the catalyst are 0.98 times that of Example 1.

[0086] Example 3

[0087] Different from Example 1: The main diameter of the cavity of the three-phase bubbling bed reactor is 1000 mm, and the height is 8000 mm. The main diameter of the gas-phase feed pipe 11 is 200 mm. The diameter of the small end of the reduced-diameter section of the gas-phase feed pipe is 100 mm, the length of the reduced-diameter section is 400 mm, and the reduced-diameter section of the pipe wall is provided with a long round hole with φ1×100 mm, and the opening area accounts for 25% of the cross-sectional area of the gas-phase feed pipe. The diameter of the cavity of the buffer part 13 is 300 mm, and the height is 300 mm;

[0088] Eight exhaust hole rings are opened on the shell of each bubble generating member 102 in the bubble generator 10. The distance between two adjacent exhaust hole rings on each bubble generating member 102 is 10 mm. The diameter of the cavity is 75 mm, and the height is 150 mm. The total opening area of the shell of each bubble generating member 102 is 25% of the cross-sectional area of the gas-phase feed pipe 11. The center distance between two adjacent bubble generating members 102 on the distribution plate 106 is 100 mm.

[0089] The frequency f of the ultrasonic transducer 14 is 40000 Hz, the liquid-phase feed rate Q is 2 kg / s, and the ultrasonic power P is 0.68 kW. The reaction operating temperature is 75 °C, the operating pressure is 7 MPa, and the raw material mass space velocity is 2 h -1 , and the mass ratio of hydrogen to isophthalonitrile is 16.

[0090] After analysis, the final product results show that the conversion rate of isophthalonitrile is 99.9%, and the selectivity is 99.9%; the service life and regeneration cycle of the catalyst are 1.03 times that of Example 1.

[0091] Example 4

[0092] Different from Example 1: The distance between two adjacent exhaust hole rings on each bubble generating member 102 is 3 mm. The total opening area of the shell of each bubble generating member 102 is 35% of the cross-sectional area of the gas-phase feed pipe 11. The center distance between two adjacent bubble generating members 102 is 150 mm.

[0093] After analysis, the final product results show that the conversion rate of isophthalonitrile is 98.2%, and the selectivity is 96.5%; the service life and regeneration cycle of the catalyst are 0.8 times that of Example 1.

[0094] Example 5

[0095] Different from Example 1: The length of the reduced-diameter section is 3 times the diameter of the gas-phase feed pipe (the main diameter of the gas-phase feed pipe 11 is 200 mm, and the length of the reduced-diameter section is 600 mm); the sum of the areas of the distribution holes opened on the peripheral wall of the reduced-diameter section is 40% of the cross-sectional area of the gas-phase feed pipe; the diameter of the cavity of the buffer part 13 is 50% of the diameter of the cavity in the solid-phase section, and the height-to-diameter ratio of the cavity in the buffer part 13 is 0.8 (the main diameter of the cavity of the three-phase bubbling bed reactor is 1000 mm, the diameter of the cavity of the buffer part 13 is 500 mm, and the height is 400 mm); the vertical height between the bubble generator 10 and the lower coarse porcelain ball layer 8 is 800 mm, and the total opening area of the shell of each bubble generating member 102 is 40% of the cross-sectional area of the gas-phase feed pipe 11;

[0096] After analysis, the results of the final product show that the conversion rate of isophthalonitrile is 95.2% and the selectivity is 96.3%; the service life and regeneration period of the catalyst are 0.75 times that of Example 1.

[0097] Example 6

[0098] Different from Example 1, the ultrasonic transducer is not provided.

[0099] After analysis, the results of the final product show that the conversion rate of isophthalonitrile is 80.5% and the selectivity is 82.3%; the service life and regeneration period of the catalyst are 0.5 times that of Example 1.

[0100] Example 7

[0101] Different from Example 1, the buffer part 13 is not provided, and the gas-phase feed pipe is set as a round pipe horizontally extending into the bottom end of the three-phase bubbling bed reactor.

[0102] After analysis, the results of the final product show that the conversion rate of isophthalonitrile is 96.3% and the selectivity is 95.6%; the service life and regeneration period of the catalyst are 0.9 times that of Example 1.

[0103] Comparative Example 1

[0104] Different from Example 1, the piston 103 is not provided in the bubble generator 10.

[0105] After analysis, the results of the final product show that the conversion rate of isophthalonitrile is 76% and the selectivity is 73%; the service life and regeneration period of the catalyst are 0.78 of that of Example 1.

[0106] Comparative Example 2

[0107] Different from Example 1, the bubble generator 10 is not provided in the three-phase bubbling bed reactor;

[0108] After analysis, the results of the final product showed that the conversion rate of isophthalonitrile was 70.2% and the selectivity was 66.5%; the service life and regeneration cycle of the catalyst were 0.5 times that of Example 1.

[0109] Comparative Example 3

[0110] The same volume as the three-phase bubble column reactor in Example 1 was used Figure 5 The device shown.

[0111] After analysis, the results of the final product showed that the conversion rate of isophthalonitrile was 90.3% and the selectivity was 90.6%;

[0112] The throughput was 80% of that in Example 1; the service life and regeneration cycle of the catalyst were 50% of that in Example 1.

[0113] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any suitable combination of each specific technical feature. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. However, these simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A bubble generating member, It is characterized in that The bubble generating member (102) comprises: A shell is provided with a cavity formed inside the shell, a plurality of exhaust holes (104) connected to the cavity are formed on the shell, and a flow stabilizing member is provided in the cavity, and the flow stabilizing member can avoid fluctuations in the discharge flow rate of the gas phase.

2. The bubble generating member according to claim 1, It is characterized in that The bottom end opening of the shell is formed as a gas phase inlet, a plurality of exhaust holes (104) are distributed on the peripheral wall of the shell, and the flow stabilizing member comprises a piston (103) capable of sliding along the axial direction of the cavity; Preferably, a plurality of exhaust hole rings are arranged on the peripheral wall of the shell and are spaced in sequence along the axial direction, and each of the exhaust hole rings includes a plurality of exhaust holes spaced in a ring shape along the circumferential direction; and / or Preferably, the bubble generating component (102) comprises a piston stopper, which can limit the piston to prevent the piston from falling out of the cavity or getting stuck at the top of the cavity.

3. A bubble generator, It is characterized in that The bubble generator (10) comprises a distribution plate (106) and a plurality of bubble generating members (102) according to claim 1 or 2 arranged on the distribution plate (106); Preferably, a plurality of through holes are provided on the distribution plate (106), each of the through holes corresponding to one of the bubble generating components (102) and being connected to the gas phase inlet of the corresponding bubble generating component (102).

4. The bubble generator according to claim 3, It is characterized in that The center distance between two adjacent bubble generating components (102) on the distribution plate (106) is 50 to 120 mm, the distance between two adjacent exhaust hole rings on each bubble generating component (102) is 5 to 20 mm, and the diameter of the cavity of each bubble generating component (102) is 50 to 100 mm.

5. A three-phase bubbling bed reaction device, It is characterized in that The three-phase bubbling bed reaction device comprises, from bottom to top, a gas phase feed section, a liquid phase feed section and a solid phase section, wherein a bubble generator (10) according to claim 3 or 4 is arranged between the gas phase feed section and the liquid phase feed section.

6. The three-phase bubbling bed reaction device according to claim 5, It is characterized in that The three-phase bubbling bed reaction device comprises a clearing component for clearing the bubble generator (10); Preferably, There are a plurality of the clearing components, the plurality of clearing components are arranged at intervals along the circumferential direction outside the three-phase bubbling bed reaction device and connected to the bubble generator (10), and more preferably the number of the plurality of clearing components is ≥4; and / or The clearing component includes a vibrating member having a vibration function, and more preferably, the clearing member includes an ultrasonic transducer (14) connected to the distribution plate (106) of the bubble generator.

7. The three-phase bubbling bed reaction device according to claim 5 or 6, It is characterized in that The gas phase feeding section is provided with a pre-distribution component for pre-distributing the gas phase fed into the cavity of the three-phase bubbling bed reaction device; Preferably, the pre-distribution member includes a gas-phase feed pipe (11), the gas-phase feed pipe (11) extends into the gas-phase feed section and bends towards the bottom of the cavity to form a bent portion, and the end of the bent portion forms a reduced-diameter section that tapers downward; More preferably, The diameter of the small end of the reduced-diameter section is 1 / 4 to 1 / 2 of the diameter of the gas-phase feed pipe, and further preferably 1 / 4 to 1 / 3; the length of the reduced-diameter section is 1 to 3 times the diameter of the gas-phase feed pipe, and further preferably 1.5 to 2.5 times; and / or A plurality of distribution holes are formed in the peripheral wall of the reduced-diameter section, and the sum of the areas of the plurality of distribution holes is 15% to 40% of the cross-sectional area of the gas-phase feed pipe, and further preferably 15% to 25%; and / or The total area of the openings on the shell of the bubble generating member (102) is 10% to 40% of the cross-sectional area of the gas-phase feed pipe (11), preferably 15% to 25%.

8. The three-phase bubbling bed reaction device according to claim 7, characterized in that, The gas-phase feed section has a buffer portion (13), and the pre-distribution member is installed in the buffer portion (13); Preferably, the diameter of the cavity of the buffer portion (13) is 20% to 50% of the diameter of the cavity of the solid-phase section, and more preferably 20% to 40%; and / or Preferably, the height-diameter ratio of the cavity of the buffer portion (13) is 0.8 to 1.5, and more preferably 1 to 1.5; and / or The height-diameter ratio of the three-phase bubbling bed reaction device is 5 to 12; and / or The solid-phase section sequentially includes a pressure grid (3), an upper layer of coarse porcelain balls (4), an upper layer of fine porcelain balls (5), a catalyst bed layer (6), a lower layer of fine porcelain balls (7), a lower layer of coarse porcelain balls (8) and a support grid (9) from top to bottom; Preferably, the vertical height of the bubble generator (10) from the lower layer of coarse porcelain ball layer (8) is 300 to 800 mm, and more preferably 400 to 600 mm; and / or Preferably, the three-phase bubbling bed reaction device is provided with a floating limiting member.

9. The application of the three-phase bubbling bed reaction device according to any one of claims 5-8 in chemical absorption, oxidation reaction and hydrogenation reaction, preferably in the application of preparing m-xylylenediamine by hydrogenating isophthalonitrile.

10. A method for preparing m-xylylenediamine, characterized in that, This method uses the three-phase bubbling bed reaction device according to any one of claims 5-8, wherein, isophthalonitrile is fed into the liquid-phase feed section, and hydrogen is fed through the bubble generator (10) so that hydrogen contacts with isophthalonitrile to generate m-xylylenediamine.

11. According to the method of claim 10, wherein, The contact conditions include: The reaction temperature is 60 to 90 °C, the pressure is 6 to 10 MPa, and the mass hourly space velocity of the raw material is 0 to 4 h -1 ; and / or The mass ratio of hydrogen to isophthalonitrile is 5 to 20; and / or Use an ultrasonic transducer (14) to clear blockages in the bubble generator (10), where the power of the ultrasonic transducer (14) Wherein, P - the power of the ultrasonic generator, kw; f - the frequency of the ultrasonic generator, Hz; s——Cross-sectional area of the bubble generator, m 2 ; Q - the liquid-phase feed rate, kg / s; η - the liquid-phase viscosity, kg / (m·s); h - the height of the bubble generator, m.

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