Method for synthesizing mixed phenylenediamine through hydrogenation of mixed dinitrobenzene
By combining a jet-type supergravity multiphase reaction device with a palladium-carbon catalyst, the problems of high cost, low efficiency, and low safety in existing phenylenediamine synthesis methods have been solved, achieving efficient and safe phenylenediamine production.
Patent Information
- Application Number
- CN202511724694.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-24
- Publication Date
- 2026-02-10
AI Technical Summary
Existing methods for synthesizing phenylenediamine are costly, inefficient, and unsafe. Mass transfer rate limits the reaction rate, leading to increased production costs and reduced safety.
The hydrogenation of mixed dinitrobenzene to mixed phenylenediamine was carried out using a jet-type hypergravity multiphase reaction device. The device utilizes components such as a ring reactor, jet ejector, hypergravity drum, and heat exchanger to achieve enhanced mass and heat transfer in the gas-liquid-solid three-phase system. Palladium on carbon catalyst was used for the reaction.
It improves the hydrogenation reaction rate, reduces catalyst usage and production costs, increases production efficiency, and achieves green and efficient synthesis of phenylenediamine, while also ensuring high equipment safety.
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Figure CN121494727A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fine chemical technology, and in particular to a method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene. Background Technology
[0002] Phenylenediamine is an important fine chemical raw material and key intermediate. As one of the simplest aromatic diamines, it has a wide range of applications. m-Phenylenediamine is widely used in the dye industry for the synthesis of intermediates for azo dyes, reactive dyes, and sulfur dyes. It is also used to prepare hair dyes, color developers, petroleum additives, and cement accelerators. Simultaneously, m-Phenylenediamine has broad applications in materials synthesis, being used to produce various high-performance materials such as specialty fibers (aramid 1313), aromatic polyamides, and polyurethanes to meet the needs of specialized fields such as aerospace. o-Phenylenediamine is mainly used in the production of vat dyes, fur dyes, surfactants, photosensitive materials, antioxidants, antifreeze agents, pharmaceuticals, and pesticides. p-Phenylenediamine is mainly used as an intermediate for azo disperse dyes, acid dyes, direct dyes, and sulfur dyes, and is also widely used in the production of aromatic polyamides and polyurethanes.
[0003] There are many methods for producing phenylenediamine, among which the main methods for synthesizing m-phenylenediamine include chemical reduction, electrolytic reduction, and catalytic hydrogenation. Chemical reduction typically uses reducing agents such as iron powder, generating large amounts of aromatic amine-containing wastewater and solid waste during the reaction, causing severe pollution. Due to environmental restrictions and outdated technology, chemical reduction is gradually being phased out. Electrolytic reduction is costly and involves complex equipment, making large-scale production difficult. o-Phenylenediamine is prepared by reducing o-nitroaniline with sodium sulfide, resulting in large wastewater discharge, high costs, and severe environmental pollution. Therefore, more and more companies are seeking green, environmentally friendly, and clean production methods to produce phenylenediamine.
[0004] Currently, catalytic hydrogenation is the most common process for synthesizing phenylenediamine both domestically and internationally. The mainstream method involves the direct addition of hydrogen to dinitrobenzene using alcohols as solvents under the action of a catalyst. In the industrial production of phenylenediamine, stirred tank reactors (STRs) are widely used. However, STRs suffer from several drawbacks due to their structure, including limited mass transfer. The mass transfer rate restricts the macroscopic reaction rate, and a slower mass transfer rate prolongs the reaction time. To meet the reaction requirements, a larger number of STRs with greater volume are typically needed, which not only increases production costs but also reduces the inherent safety of the reaction.
[0005] Therefore, how to disclose a novel method for synthesizing phenylenediamine, improve reaction rate and production efficiency, reduce the size of industrial equipment, reduce costs and waste emissions, and provide a safe method for synthesizing phenylenediamine is a problem that urgently needs to be solved in this field. Summary of the Invention
[0006] In view of this, the present invention provides a method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene, so as to solve the problems of high cost, low efficiency and low safety of existing phenylenediamine synthesis methods.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzenes includes the following steps: Mixed dinitrobenzene, a polar solvent, and a catalyst are added to a jet-type hypergravity multiphase reaction apparatus. Under a hydrogen atmosphere, the mixed dinitrobenzene and the polar solvent are circulated in the jet-type hypergravity multiphase reaction apparatus to carry out the reaction and obtain mixed phenylenediamine. The jet-type hypergravity multiphase reaction device includes an annular reactor, a jet ejector, a hypergravity drum, a heat exchanger, a circulating pump, a gas circulation pipeline, and an ejector intake port.
[0008] Preferably, the mass ratio of the mixed dinitrobenzene to the polar solvent is 0.2~2:1; The mass ratio of the catalyst to the mixed dinitrobenzene is 0.02~0.1:1.
[0009] Preferably, the mixed dinitrobenzene includes one or more of o-dinitrobenzene, m-dinitrobenzene, and p-dinitrobenzene; The polar solvent includes one or more of methanol, ethanol, N,N-dimethylformamide and water; The catalyst includes a palladium-on-carbon catalyst, and the particle size of the catalyst is 10-40 mesh.
[0010] Preferably, the mass ratio of o-dinitrobenzene, m-dinitrobenzene and p-dinitrobenzene in the mixed dinitrobenzene is 1~12:86~98.9:0.1~2.
[0011] Preferably, the reaction temperature is 80~160℃, the reaction pressure is 0.5~4MPa, and the reaction time is 0.5~1.5h.
[0012] Preferably, the catalyst is packed in a centrifugal drum; The rotational speed of the supergravity drum is 100~500 rpm.
[0013] Preferably, the circulating flow relies on a circulating pump with a flow rate of 1.5~2.5 m³ / s. 3 / h.
[0014] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: 1. This invention greatly improves the mass transfer efficiency of the gas-liquid-solid three phases during hydrogenation. The external heat exchanger eliminates the limitation of the heat exchange surface on the size of the reaction equipment, fundamentally solving the problem of heat transfer due to the high exothermic intensity caused by the increased hydrogenation reaction rate, thus achieving efficient mass and heat transfer. 2. Automatic loading and unloading of catalyst particles reduces catalyst abrasion on the equipment during production and reduces the labor intensity of catalyst transportation; 3. The method of this invention is simple to operate and stable; it has high hydrogenation efficiency, with a total space-time yield of up to 0.65 t / (m³). 3 •h); catalyst usage reduced by more than 20%; 4. The mixed dinitrobenzene synthesis method disclosed in this invention has the characteristics of stable operation, high hydrogenation efficiency, fast mass and heat transfer, convenient catalyst application, and intrinsic safety. It is a green and efficient synthesis method. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0016] Figure 1 This is a schematic diagram of the jet-type hypergravity multiphase reaction device of the present invention; wherein, 1. annular reactor, 2. jet ejector, 3. hypergravity drum, 4. heat exchanger, 5. circulating pump, 6. gas circulation pipeline, and 7. ejector intake port. Detailed Implementation
[0017] This invention provides a method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzenes, comprising the following steps: Mixed dinitrobenzene, a polar solvent, and a catalyst are added to a jet-type hypergravity multiphase reactor. Under a hydrogen atmosphere, the mixed dinitrobenzene and the polar solvent are circulated within the jet-type hypergravity multiphase reactor to react and obtain mixed phenylenediamine.
[0018] In this invention, a schematic diagram of the jet-type hypergravity multiphase reaction device is shown below. Figure 1 As shown, it includes an annular reactor 1, a jet ejector 2, a supergravity drum 3, a heat exchanger 4, a circulating pump 5, a gas circulation pipeline 6, and an ejector intake port 7.
[0019] In this invention, the liquid phase (mixed dinitrobenzene and polar solvent) is circulated from the bottom of the annular reactor 1 through the circulation pump 5, heat exchanger 4, and ejector 2; the gas phase is circulated from the top space of the annular reactor 1 through the gas circulation pipeline 6 and the ejector intake port 7; the mass transfer between the gas and liquid phases is enhanced by the ejector 2; the catalyst particles are loaded in the supergravity drum 3; the liquid phase completes the enhancement of the mass transfer between the liquid and solid phases when it flows through the drum; the external heat exchanger 4 enhances the heat transfer of the reaction process.
[0020] In this invention, the ejector uses high-speed fluid ejected through the nozzle to form a low-pressure zone that draws in the gas phase and liquid phase for mixing, based on the Venturi effect; the liquid phase circulation is powered by a circulation pump, and the gas phase is circulated by the ejector.
[0021] In this invention, the mass ratio of the mixed dinitrobenzene to the polar solvent is 0.2 to 2:1, preferably 0.5 to 1.5:1, and more preferably 1:1.
[0022] In this invention, the mass ratio of the catalyst to the mixed dinitrobenzene is 0.02~0.1:1, preferably 0.04~0.08:1, and more preferably 0.05~0.06:1.
[0023] In this invention, the mixed dinitrobenzene includes one or more of o-dinitrobenzene, m-dinitrobenzene, and p-dinitrobenzene.
[0024] In this invention, the polar solvent includes one or more of methanol, ethanol, N,N-dimethylformamide and water.
[0025] In this invention, the catalyst includes a palladium-on-carbon catalyst, and the particle size of the catalyst is 10-40 mesh, specifically 12 mesh, 15 mesh, 18 mesh, 20 mesh, 22 mesh, 25 mesh, 28 mesh, 30 mesh, 32 mesh, 35 mesh, or 38 mesh.
[0026] In this invention, the mass ratio of o-dinitrobenzene, m-dinitrobenzene and p-dinitrobenzene in the mixed dinitrobenzene is 1~12:86~98.9:0.1~2, preferably 1~10:88~98:0.1~1.5, more preferably 2~8:90~96:0.5~1.2, even more preferably 4~6:92~95:0.8~1, and even more preferably 5:94:1.
[0027] In this invention, the reaction temperature is 80~160℃, specifically 85℃, 90℃, 95℃, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃; the reaction pressure is 0.5~4MPa, specifically 0.8MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, or 3.5MPa; and the reaction time is 0.5~1.5h, specifically 0.6h, 0.8h, 1h, 1.2h, or 1.4h.
[0028] In this invention, the catalyst is packed in a supergravity drum.
[0029] In this invention, the rotation speed of the supergravity drum is 100~500 rpm, specifically 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, or 450 rpm.
[0030] In this invention, the circulating flow relies on a circulating pump with a flow rate of 1.5~2.5 m³ / h. 3 / h, specifically 1.6m 3 / h, 1.8m 3 / h、2m 3 / h, 2.2m 3 / h, 2.4m 3 / h.
[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] Example 1
[0033] 20L jet-type hypergravity multiphase reaction device (schematic diagram shown) Figure 1 Add 2.6 kg of mixed dinitrobenzene (o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene mass ratio of 10:88:2), 10.4 kg of methanol, and 65.0 g of Pd / C catalyst (Shaanxi Ruike New Material Co., Ltd., model: D05-XTG2Q0.7-LH, 0.5% palladium spherical carbon) with a particle size of 30 mesh (catalyst loaded in a high-gravity rotating drum). Then, purge with nitrogen three times, followed by purging with hydrogen three times. Next, increase the hydrogen pressure in the system to 2.5 MPa, start the circulation pump, and set the pump flow rate to 2 m³ / h. 3The system operates at 300 rpm using a high-gravity drum, raising the temperature to 120°C and controlling the system pressure at 2.5 MPa. A hydrogenation reduction reaction is then carried out (liquid phase circulation occurs from the bottom of the annular reactor via a circulating pump, heat exchanger, and ejector; gas phase circulation occurs from the top space of the annular reactor via a gas circulation pipeline and ejector intake; gas-liquid mass transfer is enhanced by the ejector). After the reaction is complete, a mixed phenylenediamine methanol solution is obtained. Gas chromatography analysis shows a 100% conversion rate of mixed dinitrobenzene, a reaction time of 60 min, and a space-time efficiency of 0.65 t / (m²). 3 ·h).
[0034] Example 2
[0035] The only difference between this embodiment and Example 1 is that the hydrogen pressure was controlled at 2 MPa, and a mixed phenylenediamine methanol solution was obtained after the reaction was complete. Gas chromatography analysis showed that the conversion rate of the mixed dinitrobenzene was 100%, the reaction time was 65 min, and the space-time efficiency was 0.60 t / (m²). 3 ·h).
[0036] Example 3
[0037] The only difference between this embodiment and Example 1 is that the amount of mixed dinitrobenzene added is adjusted to 3.25 kg, the amount of methanol added is 9.75 kg, and the amount of Pd / C catalyst added is 81.3 g. After the reaction is complete, a mixed phenylenediamine methanol solution is obtained. Gas chromatography analysis showed that the conversion rate of mixed dinitrobenzene was 100%, the reaction time was 65 min, and the space-time efficiency was 0.60 t / (m²). 3 ·h).
[0038] Example 4
[0039] The only difference between this embodiment and Example 1 is that the amount of mixed dinitrobenzene added is adjusted to 3.9 kg, the amount of methanol added is 9.1 kg, and the amount of Pd / C catalyst added is 97.5 g. After the reaction is complete, a mixed phenylenediamine methanol solution is obtained. Gas chromatography analysis showed that the conversion rate of mixed dinitrobenzene was 100%, the reaction time was 70 min, and the space-time efficiency was 0.56 t / (m²). 3 ·h).
[0040] Example 5
[0041] The only difference between this embodiment and Example 4 is that the amount of Pd / C catalyst added was adjusted to 195.0 g, and a mixed phenylenediamine methanol solution was obtained after the reaction was complete. Gas chromatography analysis showed that the conversion rate of the mixed dinitrobenzene was 100%, the reaction time was 60 min, and the space-time efficiency was 0.65 t / (m²). 3 ·h).
[0042] Example 6
[0043] The used catalyst was reused. First, the circulation pump was shut down, but the centrifugal drum was kept running. Then, the discharge port was opened to release the mixed phenylenediamine methanol solution. At this point, the catalyst particles were still attached to the centrifugal drum. The next batch of material was added as in Example 1, with an additional 6.5g of catalyst added. The hydrogenation operation was the same as in Example 1. The catalyst was reused 5 times, achieving 100% conversion. The reaction time was 60-65 minutes, and the space-time efficiency was 0.60-0.65 t / (m²). 3 (h). Compared with autoclave hydrogenation, the catalyst is reused 3 times, after which the conversion rate decreases significantly and the amount of by-products increases. The method described reduces the catalyst usage by 23% compared to autoclave hydrogenation.
[0044] Example 7
[0045] The only difference between this embodiment and Example 1 is that the reaction pressure was adjusted to 1 MPa, and a mixed phenylenediamine methanol solution was obtained after the reaction was complete. Gas chromatography analysis showed that the conversion rate of the mixed dinitrobenzene was 100%, the reaction time was 75 min, and the space-time production efficiency was 0.52 t / (m²). 3 ·h).
[0046] Example 8
[0047] The only difference between this embodiment and Example 1 is that the reaction pressure was controlled at 3.5 MPa, and a mixed phenylenediamine methanol solution was obtained after the reaction was complete. Gas chromatography analysis showed that the conversion rate of the mixed dinitrobenzene was 100%, the reaction time was 70 min, and the space-time production efficiency was 0.56 t / (m²). 3 ·h).
[0048] Example 9
[0049] The only difference between this embodiment and Example 1 is that the reaction temperature was controlled at 85°C, and a mixed phenylenediamine methanol solution was obtained after the reaction was complete. Gas chromatography analysis showed that the conversion rate of the mixed dinitrobenzene was 100%, the reaction time was 80 min, and the space-time production efficiency was 0.49 t / (m²). 3 ·h).
[0050] Example 10
[0051] The only difference between this embodiment and Example 1 is that the reaction temperature was controlled at 150°C, and a mixed phenylenediamine methanol solution was obtained after the reaction was complete. Gas chromatography analysis showed that the conversion rate of the mixed dinitrobenzene was 100%, the reaction time was 60 min, and the space-time production efficiency was 0.65 t / (m²). 3 ·h).
[0052] Comparative Example 1
[0053] 2.6 kg of mixed dinitrobenzene (o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene in a mass ratio of 10:88:2), 10.4 kg of methanol, and 65.0 g of Pd / C catalyst (same as in Example 1) were added to a 20 L high-pressure reactor. The reactor was then purged three times with nitrogen and three times with hydrogen. The temperature was raised and controlled at 120 °C, and the reaction pressure was controlled at 2.5 MPa. After the reaction was complete, a mixed phenylenediamine methanol solution was obtained. Gas chromatography analysis showed that the conversion rate of mixed dinitrobenzene was 99.98%, the reaction time was 90 min, and the space-time efficiency was 0.43 t / (m²). 3 ·h).
[0054] Compared with Comparative Example 1, Embodiment 1 of the present invention has a shorter reaction time and higher space-time efficiency.
[0055] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0056] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene, characterized in that, Includes the following steps: Mixed dinitrobenzene, a polar solvent, and a catalyst are added to a jet-type hypergravity multiphase reaction apparatus. Under a hydrogen atmosphere, the mixed dinitrobenzene and the polar solvent are circulated in the jet-type hypergravity multiphase reaction apparatus to carry out the reaction and obtain mixed phenylenediamine. The jet-type hypergravity multiphase reaction device includes an annular reactor, a jet ejector, a hypergravity drum, a heat exchanger, a circulating pump, a gas circulation pipeline, and an ejector intake port.
2. The method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene according to claim 1, characterized in that, The mass ratio of the mixed dinitrobenzene to the polar solvent is 0.2~2:1; The mass ratio of the catalyst to the mixed dinitrobenzene is 0.02~0.1:
1.
3. The method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene according to claim 1 or 2, characterized in that, The mixed dinitrobenzene includes one or more of ortho-dinitrobenzene, meta-dinitrobenzene and para-dinitrobenzene; The polar solvent includes one or more of methanol, ethanol, N,N-dimethylformamide and water; The catalyst includes a palladium-on-carbon catalyst, and the particle size of the catalyst is 10-40 mesh.
4. The method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene according to claim 3, characterized in that, The mass ratio of o-dinitrobenzene, m-dinitrobenzene, and p-dinitrobenzene in the mixed dinitrobenzene is 1~12:86~98.9:0.1~2.
5. The method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene according to claim 4, characterized in that, The reaction temperature is 80~160℃, the reaction pressure is 0.5~4MPa, and the reaction time is 0.5~1.5h.
6. The method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene according to claim 4 or 5, characterized in that, The catalyst was packed into a centrifugal rotating drum; The rotational speed of the supergravity drum is 100~500 rpm.
7. The method for synthesizing mixed phenylenediamine by hydrogenation of mixed dinitrobenzene according to claim 6, characterized in that, The circulating flow relies on a circulating pump with a flow rate of 1.5~2.5m³. 3 / h.