Continuous production process and device of xylylenediamine compound

Abstract

A continuous production process of a xylylenediamine compound comprises the following steps: a, mixing an aromatic dinitrile raw material, an organic composite solvent, a catalyst and an auxiliary agent according to a preset proportion to form a reaction raw material, and conveying the reaction raw material to the lower part of a hydrogenation reactor; b, hydrogen is input from the bottom of the hydrogenation reactor in a jet mode, the reaction raw materials and the hydrogen are subjected to a contact reaction, and the hydrogen is further used for providing driving force needed by reaction material airlift; and c, conveying the reaction material to the upper part of the hydrogenation reactor, and carrying out cyclone separation operation and the like. A device for realizing the continuous production process comprises a hydrogenation reactor, a raw material supply unit, a hydrogen circulation supply unit, a product filtering unit, a product buffer tank and the like. The invention relates to the field of organic and fine chemical synthesis, realizes continuous, stable, automatic and simple production of xylylenediamine compounds, and has the technical advantages of simplifying the production process, optimizing the reaction conditions, improving the safety and economy, saving energy, reducing consumption and the like.

Description

Technical Field

[0001] This application relates to the field of organic and fine chemical synthesis, and in particular to a continuous production process and apparatus for phenylenediamine compounds. Background Technology

[0002] Phenylenediamine can be classified into 1,3-phenylenediamine (m-phenylenediamine) and 1,4-phenylenediamine (p-phenylenediamine) according to the position of the substituents. These two isomers are important chemical raw materials due to their excellent physicochemical properties. They are commonly used as low-toxicity, room-temperature curing agents for epoxy resins, and also as raw materials in the production of photosensitive plastics, rubber additives, polyurethane resins, and coatings, as well as intermediates in organic synthesis.

[0003] Currently, the industrial preparation of phenylenediamine compounds mainly follows three routes: Multiphase hydrogenation in batch autoclaves or series stirred tanks – using Raney nickel or supported nickel / cobalt catalysts under high temperature and pressure conditions; frequent stop-start cycles during operation or hydrogenation reaction; high energy consumption and catalyst wear during stirring; and the imine-polymer side reaction easily leading to rapid activity decay. Continuous hydrogenation in fixed beds or bubbling / trickling beds – relying on high pressure or high hydrogen space velocity to compensate for mass transfer resistance; requiring complex internal components such as fine distributors and bubble generators; high equipment investment and maintenance costs; and the gas-liquid distribution imbalance still easily leads to bed overheating and catalyst coking. A series process of "ammonia oxidation-liquid ammonia dissolution-fixed bed hydrogenation" – suppressing side reactions with liquid ammonia or high-concentration amine solvents; however, the entire process involves multiple stages of operation, including vacuum distillation, cryogenic dissolution, and high-pressure hydrogenation, increasing both energy consumption and safety risks.

[0004] For example, Chinese patent CN101337894B discloses a method for the continuous hydrogenation of m-phenylenediamine in a stirred tank reactor, using isophthalonitrile as a raw material for multiphase hydrogenation. This method involves a hydrogenation reactor containing at least two stirred tanks connected in series, where a mixture of isophthalonitrile and solvent, along with hydrogen gas, is contacted with a particulate solid catalyst for a continuous hydrogenation reaction. The reaction liquid flowing out of the final stirred tank and the solid catalyst continuously enter a separator for solid-liquid separation. The separated reaction liquid yields the target product after further separation. The separated catalyst is regenerated and recycled back to the hydrogenation reactor. This method uses a stirred tank reactor, which has a complex structure, requiring high manufacturing capabilities for the agitator and is not conducive to large-scale production. Furthermore, the subsequent solid-liquid separation of the catalyst further complicates the process and places higher demands on the catalyst's strength and lifespan.

[0005] For example, Chinese patent application CN114671769A discloses a continuous process for producing m-phenylenediamine. This method involves contacting isophthalonitrile, solvent, and reaction aids with a particulate solid catalyst under hydrogen pressure to perform a three-phase hydrogenation reaction. The mixture then enters a solid-liquid separator, where the separated liquid is the target product. The catalyst after solid-liquid separation is recycled; its activity decreases, it is reactivated, and then recycled again. This method incorporates a separator within the reactor, dividing it into a separation zone and a quiescent zone. The resulting mixed solution is returned to the reactor for further reaction after solid-liquid separation. This process not only consumes a large amount of energy and has low production efficiency, but the solid-liquid separation process also causes significant catalyst wear. Furthermore, the design pressure of the reactor, separator, and solid-liquid separator must be kept consistent with the reactor, resulting in high equipment investment and subsequent maintenance costs.

[0006] For example, Chinese patent application CN120132629A discloses a method for preparing m-phenylenediamine, a bubble generating component, a bubble generator, and a three-phase bubbling bed reactor. It mainly addresses the problems of uneven gas distribution, easy clogging of the bubble generator, and low product quality in existing technologies. The method involves feeding isophthalonitrile into the liquid feed section of the three-phase bubbling bed reactor and feeding hydrogen through the bubble generator, allowing the hydrogen to contact the isophthalonitrile to generate m-phenylenediamine. It is worth noting that this method improves the mass transfer efficiency and operability of the bubbling bed through complex bubble micronization and online unclogging measures. However, it comes at the cost of high pressure, high hydrogen consumption, and multi-stage fine components, resulting in significant equipment investment, energy consumption, and maintenance burdens. Furthermore, the fixed-bed configuration limits its application to long-cycle, low-pressure scale-up conditions.

[0007] For example, Chinese patent CN101768083B discloses a method for preparing phenylenediamine, which involves hydrogenating dicyanobenzene obtained from the ammonia oxidation of xylene to produce phenylenediamine in high yield while extending catalyst life. This method employs a series of processes: "ammonia oxidation-liquid ammonia dissolution-fixed-bed liquid-phase hydrogenation." First, m / p-xylene is ammonia-oxidized in the gas phase under the action of a vanadium / chromium catalyst to generate dinitrile, which is then absorbed by an organic solvent. After vacuum distillation to remove low-boiling impurities, molten dinitrile is obtained, which is then dissolved in liquid ammonia or a liquid ammonia-aromatic mixed solvent and filtered to remove high-boiling impurities such as polytriazine. Subsequently, liquid-phase hydrogenation is carried out in a high-pressure fixed bed filled with catalyst, preferably at 3-20 MPa and 40-120°C. The product is then distilled twice to obtain phenylenediamine. The limitations of this method are: reliance on a high-concentration liquid ammonia system; equipment requiring high-pressure / low-temperature corrosion resistance; poor safety and high energy consumption; long process with multiple stages; complex investment and operation; low product selectivity and limited product yield due to high-pressure and high-temperature process conditions.

[0008] For example, Chinese patent application CN116199584A discloses a method for preparing m-phenylenediamine by low-pressure hydrogenation, using a composite nickel catalyst in a solvent to prepare m-phenylenediamine from isophthalonitrile by hydrogenation. This method has good reactivity, high selectivity and yield, effectively reduces the occurrence of side reactions, has mild process conditions, low catalyst consumption, good product quality, and reduced production costs. Although the pressure is reduced, this method is still a batch high solvent ratio operation, requiring mechanical stirring and repeated pressure increases and decreases. It is limited by the intermittent hydrogenation method, resulting in high energy consumption and long downtime for reactor changes. The composite nickel preparation and activation steps are complex, and the catalyst is easily worn and deactivated in intermittent cycles, requiring frequent replenishment. To suppress side reactions, additional base / amine deamination inhibitors need to be added, increasing the system composition and post-processing load. The high volume of solvent leads to high energy consumption for distillation recovery. The product purity is limited by residual 3-cyanobenzylamine, affecting product quality.

[0009] Overall, the above processes generally suffer from problems such as high reaction temperature and pressure, short catalyst lifetime, difficulty in solid-liquid separation or catalyst recycling, heavy solvent consumption and post-processing burden, and product purity limited by 3-cyanobenzylamine residue. These issues make it difficult to meet the demands for low energy consumption, long production cycles, automation, and large-scale safe production. Therefore, there is an urgent need to develop a safe and reliable continuous production process and apparatus for phenylenediamine compounds. Summary of the Invention

[0010] In view of this, this application provides a continuous production process and apparatus for phenylenediamine compounds, in order to at least partially solve the above-mentioned technical problems.

[0011] On the one hand, this application provides a continuous production process for phenylenediamine compounds, comprising the following steps:

[0012] Step a: Aromatic dinitrile raw material, organic composite solvent, transition metal catalyst and alkaline auxiliaries are mixed in a preset ratio to form reaction raw material, and then transported to the lower part of the hydrogenation reactor;

[0013] Step b, hydrogen gas is jetted into the bottom of the hydrogenation reactor, and the reactants react with the hydrogen gas to generate a reaction material containing phenylenediamine products. The hydrogen gas is also used to provide the driving force required for the gas lift of the reaction material.

[0014] Step c: The reactants are transported to the top of the hydrogenation reactor for cyclone separation to obtain a gas phase I and a liquid phase I. The gas phase I is compressed and enters the hydrogen circulation pipeline. The liquid phase I is subjected to solid-liquid separation to obtain a clear liquid containing phenylenediamine products and a turbid liquid containing catalyst. The clear liquid is transported to a product buffer tank, and the turbid liquid is discharged periodically.

[0015] The aforementioned continuous production process may also have the following characteristics:

[0016] Step c further includes a pre-compression gas-liquid separation operation and a post-compression gas-liquid separation operation. The first gas phase is separated into a second gas phase and a second liquid phase by the pre-compression gas-liquid separation operation. The second gas phase is then separated into a third gas phase and a third liquid phase by the post-compression gas-liquid separation operation after compression. The third gas phase and the newly supplied hydrogen are transported to the bottom of the hydrogenation reactor, and the second liquid phase and the third liquid phase are transported to the product buffer tank.

[0017] The aforementioned continuous production process may also have the following characteristics:

[0018] In step a, the aromatic dinitrile raw material is selected from isophthalonitrile, terephthalonitrile, or a mixture thereof, and the target product obtained corresponds to m-phenylenediamine, terephthalamide, or a mixture thereof; the organic composite solvent is a mixed solvent composed of aromatic hydrocarbon solvent and low-carbon alcohol solvent; the transition metal catalyst is selected from any one of the following: framework nickel, framework cobalt, framework iron, supported nickel, supported nickel-copper, or supported nickel-molybdenum metal catalyst; the alkaline promoter is sodium hydroxide and / or potassium hydroxide;

[0019] The mass ratio of the aromatic dinitrile raw material to the organic composite solvent is set to 1:(2-4);

[0020] The mass ratio of the aromatic hydrocarbon solvent to the low-carbon alcohol solvent is set to (1-6):1;

[0021] The mass concentration of the transition metal catalyst in the hydrogenation reactor is set to 1% to 20%.

[0022] The mass ratio of the alkaline auxiliary agent to the aromatic dinitrile raw material is set to 0.2-3%.

[0023] The aforementioned continuous production process may also have the following characteristics:

[0024] The organic composite solvent is a mixed solvent composed of an aromatic hydrocarbon solvent containing 6-9 carbon atoms and a low-carbon alcohol solvent containing 1-4 carbon atoms;

[0025] The transition metal catalyst is a framework nickel, the average particle size of the framework nickel is set to 50-300 mesh, and the mass concentration of the framework nickel is set to 5%-10%.

[0026] The aforementioned continuous production process may also have the following characteristics:

[0027] In step b, the reaction temperature is set to 60–80°C, the pressure is set to 1.0–3.0 MPa, the apparent gas velocity of the hydrogen inlet is set to 0.03–0.5 m / s, the hydrogenation reactor is a multi-stage airlift circulating reactor, and the space time of the hydrogenation reactor is set to 1–2 h.

[0028] Furthermore, this application also provides an apparatus for realizing the aforementioned continuous production process, including a hydrogenation reactor, a raw material supply unit, a hydrogen circulation supply unit, a product filtration unit, and a product buffer tank.

[0029] The hydrogenation reactor is configured as a multi-stage airlift circulating reactor, which includes a lower reaction unit and an upper separation unit. The reaction unit is used to realize the contact reaction of the aromatic dinitrile feedstock, the transition metal catalyst, the basic additive and the hydrogen. The separation unit is used to realize the cyclone separation operation of the reactants. The bottom of the reaction unit is also provided with a jet hole for the hydrogen jet input.

[0030] The output port of the raw material supply unit is configured to connect to the reaction unit at the bottom of the hydrogenation reactor. The hydrogen supply port of the hydrogen circulation supply unit is configured to connect to the hydrogen jet hole at the bottom of the reaction unit. The input end of the product filtration unit is configured to connect to the separation unit. The product filtration unit has a built-in catalyst filtration element. The clear liquid output port of the product filtration unit is configured to connect to the product buffer tank.

[0031] The above-mentioned device may also have the following characteristics:

[0032] The hydrogen circulation supply unit includes a pre-compression buffer tank, a compressor, and a post-compression buffer tank connected in sequence by pipelines.

[0033] The inlet of the pre-compression buffer tank is configured to receive the I-phase gas output from the separation unit, and the gas phase outlet of the post-compression buffer tank is configured to connect to the bottom of the reaction unit. A new hydrogen inlet is also provided between the gas phase outlet and the reaction unit. The liquid phase outlets of both the pre-compression buffer tank and the post-compression buffer tank are configured to connect to the product buffer tank.

[0034] The above-mentioned device may also have the following characteristics:

[0035] The hydrogenation reactor has a built-in first inner sleeve and a guide tube that cooperate with each other; the lower part of the reaction unit is also provided with a raw material inlet and a catalyst feeding port for the unit before start-up.

[0036] The separation unit of the hydrogenation reactor has a second inner sleeve and a hydrocyclone that work together.

[0037] The above-mentioned device may also have the following characteristics:

[0038] The cross-sectional area of ​​the reaction unit is set to be smaller than that of the separation unit.

[0039] The above-mentioned device may also have the following characteristics:

[0040] The raw material supply unit includes a raw material buffer tank, which has a built-in stirring assembly. The top of the raw material buffer tank is provided with a feed inlet, and the bottom of the raw material buffer tank is provided with a discharge outlet.

[0041] The product filtration unit includes a vertical filter tank, with a reaction product inlet located in the lower middle part of the vertical filter tank, a clear liquid outlet located at the top of the vertical filter tank, and a turbid liquid outlet located at the bottom of the vertical filter tank.

[0042] Therefore, compared with existing related technologies, this application's continuous production technology for phenylenediamine compounds includes at least the following innovative aspects:

[0043] 1. Synergistic innovation of bottom quantitative feeding and jet hydrogen: Aromatic dinitrile raw materials, organic composite solvents, transition metal catalysts and alkaline additives are continuously added from the bottom of the reactor, which can quickly form a homogeneous slurry in the inlet area, solving the problems of local enrichment and dead zones that are easy to occur in traditional top-down feeding reactors; At the same time, hydrogen is introduced from the bottom in the form of a jet, which has the dual function of supplying hydrogen and driving gas rise, and can construct a stable rising-return circulation, which can significantly improve the gas-liquid-solid three-phase mass transfer coefficient.

[0044] 2. Innovative gas lift circulation without mechanical stirring: Relying on hydrogen jets to provide continuous and uniform power, there is no need for external mechanical stirring devices; the continuous gas lift mode eliminates the repeated heating-pressurization and gas replacement process in the batch reactor, reduces the number of times the reactor inner wall is pressurized, reduces the equipment fatigue decay rate, and extends the equipment service life.

[0045] 3. Innovative upper cyclone separation / gas-liquid two-stage closed-loop recovery: The separation unit has a built-in inner sleeve-cyclone separator, which significantly improves the gas-liquid separation efficiency. It can immediately remove unconsumed hydrogen and achieve closed-loop circulation through the compressor circuit, which greatly reduces hydrogen loss compared with intermittent depressurization. After the separated liquid phase I is treated in an online solid-liquid stage, the clear liquid of phenylenediamine products is transported to the product buffer tank, while the turbid catalyst liquid is automatically discharged and periodically recovered.

[0046] This application employs a continuous production technology for phenylenediamine compounds, achieving continuous, stable, automated, and simplified production of these compounds. Specific advantages are as follows:

[0047] 1. Simplified production process: Reduces frequent feeding, gas replacement, pressurization and depressurization, and heating and cooling processes; eliminates the need for complex internal components such as bubble generators, reducing equipment investment and maintenance costs.

[0048] 2. Optimize reaction conditions: lower reaction temperature and pressure, longer catalyst life, easier solid-liquid separation, and lighter solvent consumption and post-processing burden.

[0049] 3. Improve safety and economy: Significantly reduce labor costs, slow down equipment fatigue damage to extend service life, and reduce reaction risks.

[0050] 4. Achieve energy saving and consumption reduction: The reaction utilizes hydrogen gas to disturb the gas source, saving stirring energy consumption; the continuous process eliminates the pressure relief step after the batch reaction ends, avoiding a large loss of hydrogen gas.

[0051] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the solutions described in the description and the accompanying drawings. Attached Figure Description

[0052] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0053] Figure 1 A continuous production apparatus for phenylenediamine compounds is provided in the embodiments of this application;

[0054] Illustration:

[0055] R - Hydrogenation reactor, V1 - Feed buffer tank, V2 - Vertical filter tank, V3 - Pre-compression buffer tank, V4 - Post-compression buffer tank, V5 - Product buffer tank, C - Compressor, P1 - Feed pump, X - Catalyst filter element;

[0056] 1-Aromatic dinitrile feedstock, 2-Mixed solvent, 3-Catalyst and auxiliaries, 4-Reaction feedstock, 5-Reactor outlet, 6-Compressor inlet, 7-Compressor outlet, 8-New hydrogen, 9-Reactor inlet, 10-Reactor outlet, 11-Turbid liquid, 12-Clear liquid, 13-Liquid phase in pre-compression buffer tank, 14-Liquid phase in post-compression buffer tank, 15-Start-up catalyst. Detailed Implementation

[0057] This application describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0058] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive scheme as defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other inventive schemes to form another unique inventive scheme as defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes may be made within the scope of the appended claims.

[0059] Furthermore, in describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described in this application, to the extent that the method or process does not depend on the specific order of steps described herein. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to performing the steps in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0060] An exemplary embodiment provides a continuous production process for phenylenediamine compounds, comprising the following steps:

[0061] Step a: Aromatic dinitrile raw material, organic composite solvent, transition metal catalyst and alkaline auxiliaries are mixed in a preset ratio to form reaction raw material, and then transported to the lower part of the hydrogenation reactor;

[0062] Step b: Hydrogen gas is jetted into the bottom of the hydrogenation reactor. The reactants react with the hydrogen gas to generate reactants containing phenylenediamine products. The hydrogen gas is also used to provide the driving force required for the gas lift of the reactants.

[0063] Step c: The reactants are transported to the top of the hydrogenation reactor for cyclone separation to obtain phase I (gas phase) and phase I (liquid phase). Phase I (gas phase) is compressed and enters the hydrogen circulation pipeline. Phase I (liquid phase) is subjected to solid-liquid separation to obtain a clear liquid containing phenylenediamine products and a turbid liquid containing the catalyst. The clear liquid is transported to the product buffer tank, and the turbid liquid is discharged periodically.

[0064] Compared with existing related technologies, the continuous production process of phenylenediamine compounds provided in the above embodiments utilizes bottom quantitative feeding and jet hydrogen synergy to continuously add raw materials, solvents, catalysts, and additives from the bottom of the reactor to form a homogeneous slurry. Simultaneously, the hydrogen jet serves both as a hydrogen supply and a driving force for gas lift, effectively enhancing three-phase mass transfer. The hydrogen jet enables gas lift circulation without mechanical stirring, reducing the number of pressure cycles on the equipment and extending its lifespan. The use of top cyclone separation and a two-stage closed-loop gas-liquid recovery system improves separation efficiency and reduces hydrogen loss. This process enables continuous, stable, automated, and simplified production, not only simplifying the process and optimizing reaction conditions but also improving safety and economy. Furthermore, it achieves energy conservation and consumption reduction by saving stirring energy and avoiding hydrogen loss.

[0065] In an exemplary embodiment of a continuous production process for phenylenediamine compounds, step c further includes a pre-compression gas-liquid separation operation and a post-compression gas-liquid separation operation. The gas phase I undergoes a pre-compression gas-liquid separation operation to obtain a gas phase II and a liquid phase II. The gas phase II undergoes a compression operation followed by a post-compression gas-liquid separation operation to obtain a gas phase III and a liquid phase III. The gas phase III and newly supplied hydrogen are transported to the bottom of the hydrogenation reactor, while the liquid phase II and liquid phase III are transported to a product buffer tank to achieve purification and transportation of products containing phenylenediamines, thereby further improving the overall yield.

[0066] In practical operation, after the I gas phase leaves the separation zone, a pre-compression buffer tank, a compressor, and a post-compression buffer tank are sequentially installed, forming a two-stage gas-liquid separation-pressurization design. The pre-compression buffer tank preferably adopts a vertical cylindrical structure, equipped with a cyclone demister and a high-efficiency wire mesh demister at the top, and an automatic level valve at the bottom; the top outlet of the tank connects to the compressor, and then enters the post-compression buffer tank. The post-compression buffer tank preferably features a baffle plate and ceramic packing combination deliquescence assembly, and is equipped with a safety valve, a condensate drain valve, and an online hydrogen content analyzer to support real-time hydrogen monitoring. The III gas phase exiting from the top of this tank mixes with fresh hydrogen before being fed into the mass flow meter and returns to the bottom of the reactor through a jet nozzle; the II and III liquid phases converge into the product buffer tank via a return pipe, which can be equipped with a back pressure valve and a dual filter to ensure continuous liquid discharge without entrainment of air bubbles. Both buffer tanks are equipped with triple interlocks for temperature, pressure, and level. The DCS distributed control system implements closed-loop regulation of compressor start / stop and jet hydrogen flow rate to maintain stable operation.

[0067] A continuous production process for phenylenediamine compounds in an exemplary embodiment.

[0068] In step a, the aromatic dinitrile raw material is selected from isophthalonitrile, terephthalonitrile or a mixture thereof, and the target product obtained is m-phenylenediamine, terephthalamide or a mixture thereof; the organic composite solvent is a mixed solvent composed of aromatic hydrocarbon solvent and low carbon alcohol solvent; the mass ratio of aromatic dinitrile raw material to organic composite solvent is set to 1:(2-4); the mass ratio of aromatic hydrocarbon solvent to low carbon alcohol solvent is set to (1-6):1.

[0069] In practice, isophthalonitrile, terephthalonitrile, or mixtures thereof can be selected as aromatic dinitrile raw materials according to the requirements of the target product to adapt to different product requirements. The organic composite solvent in the above embodiments can be a binary or ternary mixed system such as toluene-methanol, p-xylene-ethanol, 1,2,4-trimethylbenzene-methanol, ethylbenzene-methanol, or toluene-ethanol-propanol. The aromatic hydrocarbon phase can be a single C6–C9 aromatic hydrocarbon, or two or more aromatic hydrocarbons can be combined in a mass ratio (20:80 to 80:20). The low-carbon alcohol phase can be a C1–C4 monool or a blend thereof in any proportion. The mass ratio of aromatic hydrocarbon to low-carbon alcohol can be selected as 1:1, 2:1, 4:1, or 6:1 to adapt to different raw material concentrations and mass transfer requirements. When it is necessary to reduce the viscosity of the system or increase the solubility of nitriles, the aromatic hydrocarbon:low-carbon alcohol ratio can be appropriately adjusted to 1:2. The total mass ratio of aromatic dinitrile raw material to organic composite solvent can be switched between 1:2, 1:3, 1:3.5 and 1:4. Combined with the reaction pressure of 1.0–3.0 MPa and the operation range of 60–80℃, the nitrile can be completely dissolved and the liquid phase can be maintained as a single phase.

[0070] Compared with existing related technologies, the multiple adjustable organic composite solvent formulations provided in the above embodiments significantly improve mass transfer efficiency while ensuring high solubility of aromatic dinitrile, reducing system viscosity and suppressing imine polymerization side reactions; multiple mass ratio settings enable the device to maintain single-liquid phase operation under different loads, avoiding crystallization blockage, thereby achieving high nitrile conversion rate and amine selectivity under continuous operation, and significantly reducing overall energy consumption and catalyst consumption compared with traditional single solvent or autoclave processes.

[0071] In an exemplary embodiment of a continuous production process for phenylenediamine compounds, in step a, the transition metal catalyst is selected from any one of the following: skeletal nickel, skeletal cobalt, skeletal iron, supported nickel, supported nickel-copper, or supported nickel-molybdenum metal catalysts; the alkaline promoter is sodium hydroxide and / or potassium hydroxide; the mass concentration of the transition metal catalyst in the hydrogenation reactor is set to 1% to 20%; and the mass ratio of the alkaline promoter to the aromatic dinitrile feedstock is set to 0.2% to 3%.

[0072] In specific operations, the transition metal catalyst in the above embodiments can be a framework-type nickel or framework-type cobalt, with an average particle size controlled between 40 and 320 mesh to increase the external surface area; or a nickel, nickel-copper, or nickel-molybdenum catalyst supported on aluminum hydroxide, silica, or titanium oxide can be used, and a small amount of molybdenum or copper additives can be added to improve the sulfur and chlorine resistance; or a framework-type iron modified system with phosphate or borate surface modulation can be used to reduce the hydrogenation side reaction rate. In addition, the mass concentration of the catalyst in the hydrogenation reactor can be set in stages within the range of 1%-20%, for example, 10% can be added during the start-up phase, and then maintained at 5%-8% after stable operation. The alkaline additive can be sodium hydroxide, potassium hydroxide, or a combination of both. The mass ratio of the additive to the aromatic dinitrile feedstock can be selected as 0.2%-1.0% (suitable for low by-product conditions), 1.0%-2.0% (suitable for high load conditions), or 2.0%-3.0% (suitable for rapid start-up conditions). The pH value of the system can be maintained within the target range by staged addition.

[0073] Compared with existing related technologies, the multi-component tunable combination of transition metal catalyst and alkaline promoter provided in the above embodiments has the advantages of wide catalytic activity window, strong resistance to impurity impact, and online regeneration. The catalyst concentration and promoter ratio that can be adjusted as needed significantly reduce the content of high-boiling condensates by-products, effectively extending the catalyst service life. At the same time, it achieves higher conversion rate of aromatic dionitriles and higher selectivity of target amines under conditions of 1.0-3.0 MPa and 60-80℃, and the overall production cost is significantly lower than that of traditional single nickel-based systems.

[0074] In an exemplary embodiment, a continuous production process for phenylenediamine compounds is described, wherein the organic composite solvent is a mixture of an aromatic hydrocarbon solvent containing 6-9 carbon atoms and a low-carbon alcohol solvent containing 1-4 carbon atoms.

[0075] In specific operation, the organic composite solvent in the above embodiments can be any combination of the following: the aromatic hydrocarbon phase can be switched between aromatic hydrocarbons containing 6-9 carbon atoms, such as toluene, ethylbenzene, xylene with different isomers, 1,2,4-trimethylbenzene, isopropylbenzene, propenzene, methylnaphthalene, and any two or more of them, preferably one or more of toluene, xylene, and trimethylbenzene; the low-carbon alcohol phase can be selected from straight-chain or branched alcohols containing 1-4 carbon atoms, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, or tert-butanol, preferably methanol or ethanol. The mass ratio of aromatic hydrocarbon solvent to low-carbon alcohol solvent is preferably (1-4):1, so as to more effectively meet the requirements of different raw material concentrations and mass transfer.

[0076] Compared with existing related technologies, the solvent system provided in the above embodiments expands the range of aromatic hydrocarbons and low-carbon alcohols and their ratios, resulting in lower overall power consumption under the same conversion rate conditions. Furthermore, the process has greater adaptability to different equipment scales and raw material purity, significantly improving the energy efficiency and economy of continuous hydrogenation processes.

[0077] In an exemplary embodiment, a continuous production process for phenylenediamine compounds is described, wherein the transition metal catalyst is a framework nickel, the average particle size of the framework nickel is set to 50-300 mesh, and the mass concentration of the framework nickel is set to 1%-20%.

[0078] In specific operations, the transition metal catalyst in the above embodiments can be a framework nickel powder activated by alkaline solution, i.e., Raney nickel powder, whose particle size can be divided into three levels: 50-80 mesh, 80-150 mesh, and 150-300 mesh, preferably 60-200 mesh, to match different cyclic shear intensities; when it is necessary to improve the activity in the low-temperature section, a certain amount of Cu, Mo, or Co can be co-deposited on the surface of the framework nickel to form a nickel-copper, nickel-molybdenum, or nickel-cobalt auxiliary layer; the mass concentration of the catalyst in the reactor can be adjusted according to the space velocity and gas-liquid shear conditions, preferably 5-10%, and the average activity can be maintained at more than 90% of the initial value by intermittently adding fresh catalyst or online sedimentation to recover the catalyst turbidity.

[0079] Compared with existing related technologies, the optimized particle size and concentration scheme of the framework nickel catalyst provided in the above embodiments has comprehensive advantages such as high catalytic activity, good fluidization stability, low metal loss rate, and high selectivity for the target phenylenediamine, which can significantly improve the economy of continuous hydrogenation process and the operation cycle of the equipment.

[0080] In an exemplary embodiment of a continuous production process for phenylenediamine compounds, in step b, the reaction temperature is set to 60–80°C, the pressure is set to 1.0–3.0 MPa, the apparent gas velocity of hydrogen inlet is set to 0.03–0.5 m / s, preferably 0.05–0.3 m / s, the hydrogenation reactor is set to a multi-stage airlift circulating reactor, and the space time of the hydrogenation reactor is set to 1–2 h.

[0081] In specific operation, the process parameters in the above embodiments can be set in a refined manner by intervals: the reaction temperature of 60-80℃ can be further subdivided into a start-up zone of 60-65℃, a steady-state zone of 66-75℃, and a high-load zone of 76-80℃; the reaction pressure of 1.0-3.0MPa can be set to three levels—1.2-1.6MPa, 1.6-2.2MPa, and 2.2-3.0MPa—through the inlet back pressure valve to match different space velocities and hydrogen supply; the apparent hydrogen velocity of 0.03-0.10m / s can be adjusted to 0.03-0.05m / s, 0.05-0.08m / s, etc., by combining the distributor orifice diameter and the gas supply flow rate. The apparent hydrogen velocity is measured within the ranges of 0.08-0.10 m / s, 0.10-0.20 m / s, 0.20-0.30 m / s, and 0.30-0.50 m / s, and is precisely controlled in conjunction with the gas-liquid ratio. Specifically, the apparent hydrogen velocity refers to the calculated flow velocity of hydrogen as it flows through pipes, reactors, and other equipment, assuming the entire cross-sectional area is filled with gas. This apparent velocity is a macroscopic flow rate index calculated based on the total cross-sectional area of ​​the equipment, used to describe the overall flow intensity of hydrogen within the equipment. It does not represent the actual flow velocity, but it effectively reflects the flow state and process conditions, and is an important parameter in engineering design and experimental research. Furthermore, the multi-stage airlift circulating reactor can adopt a 2-10 stage internal sleeve structure, and each stage can be equipped with an external circulating cooling jacket or internal cooling coil to limit the bed temperature difference to ±2℃. Different space-time conditions of 1.0, 1.5, and 2.0 h can be achieved by adjusting the feed flow rate.

[0082] Compared with existing related technologies, the temperature and pressure division and multi-stage gas velocity coordinated control strategy provided in the above embodiments has comprehensive advantages such as uniform heat and mass transfer, high hydrogen utilization rate, high selectivity of standard phenylenediamine and low unit energy consumption, which significantly improves the industrial economy and operational safety of continuous hydrogenation process.

[0083] Reference Figure 1 As shown, an exemplary embodiment provides an apparatus for implementing the aforementioned continuous production process, including a hydrogenation reactor R, a raw material supply unit, a hydrogen circulation supply unit, a product filtration unit, and a product buffer tank V5.

[0084] The hydrogenation reactor R is configured as a multi-stage airlift circulating reactor. The hydrogenation reactor R includes a lower reaction unit and an upper separation unit. The reaction unit is used to realize the contact reaction of aromatic dinitrile feedstock 1, catalyst and auxiliary agent 3 (i.e. transition metal catalyst and basic auxiliary agent) and hydrogen. The separation unit is used to realize the cyclone separation operation of the reactants. The bottom of the reaction unit is also provided with a jet hole for hydrogen jet input.

[0085] The output port of the raw material supply unit is set to connect to the reaction unit at the bottom of the hydrogenation reactor R. The hydrogen supply port of the hydrogen circulation supply unit is set to connect to the hydrogen jet hole at the bottom of the reaction unit. The input end of the product filtration unit is set to connect to the separation unit. The product filtration unit has a built-in catalyst filter element X. The clear liquid output port of the product filtration unit is set to connect to the product buffer tank V5.

[0086] In practical operation, the multi-stage airlift circulating reactor in the above embodiments can adopt a sleeve structure of "central rising channel - annular descending channel", and an overflow cap or spiral guide vane is set at the outlet of the rising channel to enhance three-phase turbulence; the cyclone separation unit can be arranged with a conical inner cylinder or a spiral vane is added at the outlet to generate a centrifugal field to achieve rapid gas-liquid separation. Several Venturi or short-throat nozzles can be selected for the hydrogen jet orifice, evenly distributed at the bottom of the reactor to introduce circulating hydrogen and provide power for liquid circulation. The product filtration unit preferably uses a sintered metal filter element or a scraped plate filter structure, which ensures efficient catalyst retention and facilitates in-situ backflushing or low-speed scraping regeneration. Each unit and pipeline is assembled using pressure-resistant sealed connectors for easy modular maintenance.

[0087] Compared with existing related technologies, the overall solution of "multi-stage circulation + cyclone separation + online regenerable filtration" provided in the above embodiments can maintain a good gas-liquid-solid dispersion state and catalyst retention efficiency under low pressure difference, reduce frequent shutdown cleaning and component wear, and achieve long-term and stable operation of continuous hydrogenation unit, thereby significantly improving production economy and intrinsic safety level.

[0088] In one exemplary embodiment of the continuous production apparatus, the hydrogen circulation supply unit includes a pre-compression buffer tank V3, a compressor C, and a post-compression buffer tank V4 connected in sequence via pipelines. The inlet of the pre-compression buffer tank V3 is configured to input the I-phase gas output from the separation unit, and the gas phase outlet of the post-compression buffer tank V4 is configured to connect to the bottom of the reaction unit. A new hydrogen inlet, i.e., a supply interface for new hydrogen 8, is also provided between the gas phase outlet and the reaction unit. The liquid phase outlets of both the pre-compression buffer tank V3 and the post-compression buffer tank V4 are configured to connect to the product buffer tank V5.

[0089] In specific operation, the gas phase I (i.e., reactor outlet 5) undergoes pre-compression gas-liquid separation to obtain gas phase II (i.e., compressor inlet 6) and liquid phase II (i.e., pre-compression buffer tank liquid phase 13). After compression, gas phase II (i.e., compressor inlet 6) undergoes post-compression gas-liquid separation to obtain gas phase III (i.e., compressor outlet 7) and liquid phase III (i.e., post-compression buffer tank liquid phase 14). Gas phase III (i.e., compressor outlet 7) and newly supplied hydrogen (i.e., new hydrogen 8) are transported to the bottom of the reactor. Liquid phase II (i.e., pre-compression buffer tank liquid phase 13) and liquid phase III (i.e., post-compression buffer tank liquid phase 14) are transported to the product buffer tank V5.

[0090] The aforementioned pre-compression buffer tank V3 and post-compression buffer tank V4 can be any type of vertical cyclone buffer tank, horizontal corrugated plate buffer tank, hollow fiber demister buffer tank, multi-tube condenser-gravity settling integrated cryogenic buffer tank, high-efficiency cyclone separator, or horizontal buffer tank with built-in wire mesh demister. The aforementioned compressor C can be any type of diaphragm compressor, oil-lubricated screw compressor, or centrifugal multi-stage compressor. Furthermore, an automatic drain valve can be installed at the bottom of the pre-compression buffer tank V3, and a pressure-level dual interlock can be connected to the top. An anti-pulse pressure regulator and a temperature-pressure dual detection point are configured between the compressor C outlet and the post-compression buffer tank V4. The gas phase port of the post-compression buffer tank V4 and the new hydrogen 8 inlet are connected to the bottom jet nozzle of the reaction unit through a three-way mass flow control valve to prevent hydrogen venting.

[0091] Compared with existing related technologies, the continuous production device for phenylenediamine compounds provided in the above embodiments has multiple types of buffer-boost modules to ensure droplet stripping and pressure stability under different production capacity ranges, significantly reducing the risk of wear on the compressor caused by liquid slugging and oil mist; the gas phase and fresh hydrogen are mixed at a constant pressure-constant flow ratio, the purity of circulating hydrogen and the hydrogen supply pressure remain stable, reducing venting losses and improving the reliability of continuous operation of the device.

[0092] In an exemplary embodiment of the continuous production apparatus, the reaction unit of the hydrogenation reactor R has a first inner sleeve and a guide tube that cooperate with each other; the lower part of the reaction unit is also provided with a raw material inlet and a catalyst feeding port for the start-up of the apparatus; the separation unit of the hydrogenation reactor R has a second inner sleeve and a hydrocyclone that cooperate with each other.

[0093] Compared with existing related technologies, the continuous production apparatus for phenylenediamine compounds provided in the above embodiments achieves adjustable matching between gas lift drive and liquid reflux through the first inner sleeve-guide tube combination; the second inner sleeve-cyclone combination achieves high gas-liquid separation efficiency and stable circulating hydrogen flow, further improving the applicability and scale-up feasibility of the apparatus; the raw material inlet can be equipped with a tangential cutting-in type or annular gap distributed nozzle structure, and the start-up catalyst feeding port can be equipped with an embedded gate valve or a removable blind plate to facilitate the convenient addition of the start-up catalyst 15 before start-up, which facilitates rapid feeding under high pressure conditions, thereby ensuring the overall process operation stability.

[0094] It should be noted that the specific structural configurations of the aforementioned inner sleeve, guide tube, and hydrocyclone are all conventional components in this field. Their material selection, dimensional parameters, and connection methods can all be adjusted according to actual operating conditions and with reference to conventional design standards for hydrogenation reactors in the prior art. The specific structural configurations are not intended to limit the scope of protection of this application. The innovation of this application lies not in the structural improvements of these individual components, but in the overall layout design, such as the cooperation between the inner sleeve and the guide tube, and the cooperation between the second inner sleeve and the hydrocyclone, which further enables highly efficient synergy between the reaction and separation processes.

[0095] In one exemplary embodiment of the continuous production apparatus, the cross-sectional area of ​​the reaction unit is set to be smaller than that of the separation unit.

[0096] In specific operation, the device can adopt three parallel cross-sectional area configuration schemes: Scheme 1 adopts a tower-type straight section with a rapidly expanding upper section, where the diameter D1 of the reaction unit is 50%–60% of the diameter D2 of the separation unit, and a diffusion cone of a certain length is set between the two sections; Scheme 2 adopts an integral conical gradually expanding structure, where the bottom diameter D1 of the reaction section and the top diameter D2 of the separation section transition linearly at a ratio of 1:1.8, with a diffusion angle of 6°–8°; Scheme 3 adopts a stepped module, where the diameter of the reaction section is fixed at 70% of D2, and the upper part expands successively through three steps, with an expansion ratio of 1.15–1.30 for each stage, and circumferential equalizing holes and baffles are added between stages. The three schemes are respectively matched to the operating requirements of medium and low gas velocities, high conversion and high gas content, and wide load scaling.

[0097] Compared with existing related technologies, the continuous production apparatus for phenylenediamine compounds provided in the above embodiments has a reaction section cross-sectional area smaller than the separation section cross-sectional area. This allows for high upward gas velocity and enhanced mass transfer while achieving a lower surface load in the upper part, significantly reducing droplet entrainment by bubbles. The multi-stage expansion or gradual expansion structure provides flow field buffering, avoids shear backflow impact, improves gas-liquid separation efficiency, and expands the operable load range, thereby achieving stable continuous operation and efficient product separation at different production capacity levels.

[0098] In an exemplary embodiment of the continuous production apparatus, the raw material supply unit includes a raw material buffer tank V1, which has a built-in stirring assembly. The raw material buffer tank V1 has a feed inlet at its top and a discharge outlet at its bottom. The product filtration unit includes a vertical filter tank V2, which has a reaction product feed inlet at its lower middle part, a clear liquid output port at its top for outputting a clear liquid 12 containing phenylenediamine products, and a turbid liquid output port at its bottom for outputting a turbid liquid 11 containing a catalyst.

[0099] In specific operation, the raw material buffer tank V1 in the above embodiments can adopt a double-layer or triple-layer cylindrical structure. The outer layer is equipped with a circulating heat transfer oil or cooling water jacket to maintain the stability of the raw material viscosity. The stirring assembly can be an upper and lower propeller blade, an anchor agitator, or a magnetically coupled leak-free drive structure, and can be combined with radial baffles to eliminate vortices. In addition, the feed inlet can be equipped with atomizing nozzles and a metering valve in parallel to facilitate the separate addition of solid and liquid raw materials. The bottom discharge port can be equipped with a V-shaped conical bottom and a pneumatic bottom valve to reduce residue. The vertical filter tank V2 used for product filtration can be designed in sections. The internal structure can be replaced with sintered metal filter plates, wedge wire mesh filter elements, or metal fiber felt tubes depending on the working conditions. The middle and lower feed inlet can be equipped with various types of catalyst filter elements X, such as tangential guide plates or hydrocyclones, for pre-separation of coarse particles. The top clear liquid output port can be connected to an online flow meter and a pressure compensation valve, and the bottom turbid liquid output port can be connected to a screw conveyor slag discharge valve or a quick-connect valve to meet the continuous discharge requirements of different catalyst loads.

[0100] Compared with existing related technologies, the combination of the multifunctional raw material buffer tank and the vertical filter tank with replaceable filter element provided in the above embodiments has the advantages of high raw material homogeneity, stable filtration pressure drop, high catalyst closed-loop circulation efficiency, and short online maintenance time, thereby significantly improving the long-term operational reliability and product purity of the continuous production unit.

[0101] To further verify the technical effects of the above embodiments provided in this application, three sets of embodiments were subsequently selected for comparative testing. The experimental data table is shown below.

[0102]

[0103]

[0104] Example 1:

[0105] Before start-up, catalyst 15, made of Raney nickel powder with a particle size of 150 mesh, is added to the hydrogenation reactor R through the catalyst feed port to ensure a catalyst concentration of 10% within the reactor during normal operation. The raw material isophthalonitrile and mixed solvent 2 (toluene to methanol mass ratio of 2:1) are fed into the raw material buffer tank V1 from outside the boundary at a rate of 200 kg / h at a mass ratio of 1:4. The catalyst and auxiliary agent sodium hydroxide are added to the raw material buffer tank V1 at 1% of their mass relative to isophthalonitrile. After mixing in the raw material buffer tank V1, the reaction raw material 4 is pumped to the hydrogenation reactor R via the raw material inlet through the raw material feed pump P1. The hydrogenation reactor R has a space time of 1.5 h. Reactor gas 9 enters the hydrogenation reactor R from the circulating hydrogen inlet at the bottom of the reactor, with an apparent gas velocity of 0.08 m / s. The reaction temperature is controlled. At a temperature of 75℃ and a reaction pressure of 1.9MPa, the raw materials, hydrogen, and catalyst are fully contacted under the action of the internal reaction components, and a reaction occurs to produce the product m-phenylenediamine. The reactor effluent 10 leaves the hydrogenation reactor R from the reactant outlet and enters the vertical filter tank V2. The reactor effluent 5 leaves the hydrogenation reactor R from the circulating hydrogen outlet. Gas-liquid separation is achieved in the pre-compression buffer tank V3. The compressor inlet 6 enters the circulating gas compressor C. After being pressurized, the compressor effluent 7 passes through the post-compression buffer tank V4 for gas-liquid separation. The gas phase and the new hydrogen 8 are then combined and enter the hydrogenation reactor R through the circulating hydrogen inlet. Reactor effluent 10 leaves the hydrogenation reactor R from the reactant outlet and enters the vertical filter tank V2 through the reactant inlet. Under the action of the catalyst filter element X, the catalyst remains on the turbid liquid side of the filter. The clear liquid 12 enters the clear liquid side from the catalyst filter element X and exits the vertical filter tank V2 from the upper part of the clear liquid side into the product buffer tank V5. The turbid liquid 11 with a higher catalyst concentration is periodically discharged from the catalyst outlet of the catalyst filter element X for recycling. During long-term stable operation, the conversion rate of the raw material m-phenylenediamine is 100%, and the yield is 99.8%.

[0106] Example 2:

[0107] Before start-up, catalyst 15, made of Raney nickel powder with a particle size of 200 mesh, is fed into the hydrogenation reactor R through the catalyst 15 feed port, ensuring a catalyst concentration of 20% within the reactor during normal operation. The raw material isophthalonitrile and mixed solvent 2 (toluene to methanol mass ratio of 2:1) are fed into the raw material buffer tank V1 from outside the boundary at a mass ratio of 1:3 at a rate of 250 kg / h. The catalyst and auxiliary agent sodium hydroxide are added to the raw material buffer tank V1 at 0.8% of the mass of isophthalonitrile. After mixing in the raw material buffer tank V1, the reaction raw material 4 is pumped to the hydrogenation reactor R through the raw material inlet via the raw material feed pump P1. The hydrogenation reactor R has a space time of 1.2 h. Reactor gas 9 enters the hydrogenation reactor R from the circulating hydrogen inlet at the bottom of the reactor R, with an apparent gas velocity of 0.08 m / s, controlling the reaction... At a temperature of 75℃ and a reaction pressure of 2.0MPa, the raw materials, hydrogen, and catalyst are fully contacted under the action of the internal reaction components, and a reaction occurs to produce the product m-phenylenediamine. The reactor effluent 10 leaves the hydrogenation reactor R from the reactant outlet and enters the vertical filter tank V2. The reactor effluent 5 leaves the hydrogenation reactor R from the circulating hydrogen outlet. Gas-liquid separation is achieved in the pre-compression buffer tank V3. The compressor inlet 6 enters the circulating gas compressor C. After being pressurized, the compressor effluent 7 passes through the post-compression buffer tank V4 for gas-liquid separation. The gas phase and the new hydrogen 8 are then combined and enter the hydrogenation reactor R through the circulating hydrogen inlet. Reactor effluent 10 leaves the hydrogenation reactor R from the reactant outlet and enters the vertical filter tank V2 through the reactant inlet. Under the action of the catalyst filter element X, the catalyst remains on the turbid liquid side of the filter. The clear liquid 12 enters the clear liquid side from the filter element and exits the vertical filter tank V2 from the upper part of the clear liquid side into the product buffer tank V5. The turbid liquid 11 with a higher catalyst concentration is periodically discharged from the catalyst outlet of the catalyst filter element X for recycling. During long-term stable operation, the conversion rate of the raw material m-phenylenediamine is 100%, and the yield is 99.9%.

[0108] Example 3:

[0109] Before start-up, catalyst 15, made of Raney nickel powder with a particle size of 200 mesh, is added to the hydrogenation reactor R through the start-up catalyst inlet, ensuring a catalyst concentration of 20% within the reactor during normal operation. The raw material terephthalonitrile and mixed solvent 2 (toluene to methanol mass ratio of 2:1) are fed into the raw material buffer tank V1 from outside the boundary at a mass ratio of 1:3 at 200 kg / h. The catalyst and auxiliary agent sodium hydroxide are added to the raw material buffer tank V1 at 0.8% of the mass of isophthalonitrile. After mixing in the raw material buffer tank V1, the reaction raw material 4 is transported to the hydrogenation reactor R via the raw material inlet through the raw material feed pump P1. The hydrogenation reactor R has a space time of 1.5 h. Reactor gas 9 enters the hydrogenation reactor R from the circulating hydrogen inlet at the bottom of the reactor R, with an apparent gas velocity of 0.08 m / s, controlling the reaction... At a temperature of 75℃ and a reaction pressure of 2.0MPa, the raw materials, hydrogen, and catalyst are fully contacted under the action of the internal reaction components, and a reaction occurs to produce the product p-phenylenediamine. The reactor effluent 10 leaves the hydrogenation reactor R from the reactant outlet and enters the vertical filter tank V2. The reactor effluent 5 leaves the hydrogenation reactor R from the circulating hydrogen outlet. Gas-liquid separation is achieved in the pre-compression buffer tank V3. The compressor inlet 6 enters the circulating gas compressor C. After being pressurized, the compressor effluent 7 passes through the post-compression buffer tank V4 for gas-liquid separation. The gas phase and the new hydrogen 8 are then combined and enter the hydrogenation reactor R through the circulating hydrogen inlet. Reactor effluent 10 leaves the hydrogenation reactor R from the reactant outlet and enters the vertical filter tank V2 through the reactant inlet. Under the action of the catalyst filter element X, the catalyst remains on the turbid liquid side of the filter. The clear liquid 12 enters the clear liquid side from the filter element and exits the vertical filter tank V2 from the upper part of the clear liquid side into the product buffer tank V5. The turbid liquid 11 with a higher catalyst concentration is periodically discharged from the catalyst outlet of the catalyst filter element X for recycling. During long-term stable operation, the conversion rate of the raw material p-phenylenediamine is 100%, and the yield is 99.5%.

[0110] Experimental results show that the continuous process provided in the above embodiments of this application can achieve 100% conversion of aromatic dinitrile under mild conditions of only 75℃ and ≤2MPa, with the yield of the target product m / p-phenylenediamine remaining at 99.5%-99.9% (Examples 1-3). Compared with the traditional high-pressure hydrogenation method of 6-10MPa and 90-120℃ in a batch process, the innovative process proposed in this application reduces the reaction pressure by more than 70% and the reaction temperature by 20-40℃. At the same time, relying on the efficient mass transfer of the multi-stage airlift circulating reactor and the online catalyst circulation-filtration design, it can obtain near-quantitative conversion and yield, fully demonstrating the significant comprehensive advantages of the above-mentioned production equipment and preparation process proposed in this application in terms of energy consumption, safety and yield.

Claims

1. A continuous production process for phenylenediamine compounds, characterized in that, Includes the following steps: Step a: Aromatic dinitrile raw material, organic composite solvent, transition metal catalyst and alkaline auxiliaries are mixed in a preset ratio to form reaction raw material, and then transported to the lower part of the hydrogenation reactor; Step b, hydrogen gas is jetted into the bottom of the hydrogenation reactor, and the reactants react with the hydrogen gas to generate a reaction material containing phenylenediamine products. The hydrogen gas is also used to provide the driving force required for the gas lift of the reaction material. Step c: The reactants are transported to the top of the hydrogenation reactor for cyclone separation to obtain a gas phase I and a liquid phase I. The gas phase I is compressed and enters the hydrogen circulation pipeline. The liquid phase I is subjected to solid-liquid separation to obtain a clear liquid containing phenylenediamine products and a turbid liquid containing catalyst. The clear liquid is transported to a product buffer tank, and the turbid liquid is discharged periodically.

2. The continuous production process according to claim 1, characterized in that, Step c further includes a pre-compression gas-liquid separation operation and a post-compression gas-liquid separation operation. The first gas phase is separated into a second gas phase and a second liquid phase by the pre-compression gas-liquid separation operation. The second gas phase is then separated into a third gas phase and a third liquid phase by the post-compression gas-liquid separation operation after compression. The third gas phase and the newly supplied hydrogen are transported to the bottom of the hydrogenation reactor, and the second liquid phase and the third liquid phase are transported to the product buffer tank.

3. The continuous production process according to claim 1 or 2, characterized in that, In step a, the aromatic dinitrile raw material is selected from isophthalonitrile, terephthalonitrile, or a mixture thereof, and the target product obtained corresponds to m-phenylenediamine, terephthalamide, or a mixture thereof; the organic composite solvent is a mixed solvent composed of aromatic hydrocarbon solvent and low-carbon alcohol solvent; the transition metal catalyst is selected from any one of the following: framework nickel, framework cobalt, framework iron, supported nickel, supported nickel-copper, or supported nickel-molybdenum metal catalyst; the alkaline promoter is sodium hydroxide and / or potassium hydroxide; The mass ratio of the aromatic dinitrile raw material to the organic composite solvent is set to 1:(2-4); The mass ratio of the aromatic hydrocarbon solvent to the low-carbon alcohol solvent is set to (1-6):1; The mass concentration of the transition metal catalyst in the hydrogenation reactor is set to 1% to 20%. The mass ratio of the alkaline auxiliary agent to the aromatic dinitrile raw material is set to 0.2-3%.

4. The continuous production process according to claim 3, characterized in that, The organic composite solvent is a mixed solvent composed of an aromatic hydrocarbon solvent containing 6-9 carbon atoms and a low-carbon alcohol solvent containing 1-4 carbon atoms; The transition metal catalyst is a framework nickel, the average particle size of the framework nickel is set to 50-300 mesh, and the mass concentration of the framework nickel is set to 5%-10%.

5. The continuous production process according to claim 1 or 2, characterized in that, In step b, the reaction temperature is set to 60–80°C, the pressure is set to 1.0–3.0 MPa, the apparent gas velocity of the hydrogen inlet is set to 0.03–0.5 m / s, the hydrogenation reactor is a multi-stage airlift circulating reactor, and the space time of the hydrogenation reactor is set to 1–2 h.

6. An apparatus for implementing the continuous production process according to claim 1 or 2, characterized in that, It includes a hydrogenation reactor, a raw material supply unit, a hydrogen circulation supply unit, a product filtration unit, and a product buffer tank; The hydrogenation reactor is configured as a multi-stage airlift circulating reactor, which includes a lower reaction unit and an upper separation unit. The reaction unit is used to realize the contact reaction of the aromatic dinitrile feedstock, the transition metal catalyst, the basic additive and the hydrogen. The separation unit is used to realize the cyclone separation operation of the reactants. The bottom of the reaction unit is also provided with a jet hole for the hydrogen jet input. The output port of the raw material supply unit is configured to connect to the reaction unit at the bottom of the hydrogenation reactor. The hydrogen supply port of the hydrogen circulation supply unit is configured to connect to the hydrogen jet hole at the bottom of the reaction unit. The input end of the product filtration unit is configured to connect to the separation unit. The product filtration unit has a built-in catalyst filtration element. The clear liquid output port of the product filtration unit is configured to connect to the product buffer tank.

7. The apparatus according to claim 6, characterized in that, The hydrogen circulation supply unit includes a pre-compression buffer tank, a compressor, and a post-compression buffer tank connected in sequence by pipelines. The inlet of the pre-compression buffer tank is configured to receive the I-phase gas output from the separation unit, and the gas phase outlet of the post-compression buffer tank is configured to connect to the bottom of the reaction unit. A new hydrogen inlet is also provided between the gas phase outlet and the reaction unit. The liquid phase outlets of both the pre-compression buffer tank and the post-compression buffer tank are configured to connect to the product buffer tank.

8. The apparatus according to claim 6, characterized in that, The hydrogenation reactor has a built-in first inner sleeve and a guide tube that cooperate with each other. The lower part of the reaction unit is also provided with a raw material inlet and a catalyst feeding port for the unit before start-up. The separation unit of the hydrogenation reactor has a second inner sleeve and a hydrocyclone that work together.

9. The apparatus according to claim 6, characterized in that, The cross-sectional area of ​​the reaction unit is set to be smaller than that of the separation unit.

10. The apparatus according to claim 6, characterized in that, The raw material supply unit includes a raw material buffer tank, which has a built-in stirring assembly. The top of the raw material buffer tank is provided with a feed inlet, and the bottom of the raw material buffer tank is provided with a discharge outlet. The product filtration unit includes a vertical filter tank, with a reaction product inlet located in the lower middle part of the vertical filter tank, a clear liquid outlet located at the top of the vertical filter tank, and a turbid liquid outlet located at the bottom of the vertical filter tank.

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