Process for producing m-xylylenediamine

Abstract

The invention relates to the technical field of preparation of m-xylylenediamine, in particular to a process for producing m-xylylenediamine. Comprising the following steps: adding solid isophthalonitrile into a material dissolving unit, then introducing a solvent, stirring, and after the isophthalonitrile is completely dissolved, heating to obtain an isophthalonitrile solution; the method comprises the following steps: introducing an isophthalonitrile solution into a reaction unit, and carrying out hydrogenation reaction on the isophthalonitrile solution and hydrogen in a bed layer of a catalyst to obtain a crude product m-xylylenediamine; introducing the crude product m-xylylenediamine into a material receiving unit, separating gas from liquid, and rectifying and purifying the liquid to obtain m-xylylenediamine; the conversion rate of isophthalonitrile reaches 100%, the selectivity of m-xylylenediamine is 98% or above, and the catalyst is simple in preparation method and stable in performance.

Description

Technical Field

[0001] The present invention relates to the technical field of m-xylylenediamine preparation, and in particular to a process for producing m-xylylenediamine. Background Art

[0002] Due to its unique molecular structure, m-xylylenediamine (MXDA) exhibits active chemical properties. It readily reacts with carbon dioxide in air to form amine salts, resulting in a yellowing effect. The compound contains two active primary amine groups, which impart excellent reactivity, making it an important raw material for epoxy resin curing agents and nylon modified polymerization monomers, with key applications in coatings, electronic packaging, and composite materials. Global MXDA market demand continues to grow, and high-end products require strict control of 3-cyanobenzylamine impurities (mass fraction must be below 0.2%).

[0003] Chinese invention patent CN114671769A uses a nickel-aluminum catalyst to achieve a 100% conversion rate at 2-6 MPa and 79-90°C, while BASF's patent WO2005026098 uses a doped nickel-cobalt catalyst to achieve a 90% yield at a high pressure of 15-20 MPa. These differences in process parameters highlight the importance of catalyst system development. Summary of the Invention

[0004] The present invention provides a process for producing meta-xylylenediamine (MXDA), comprising the following steps:

[0005] Solid isophthalonitrile (IPN) is put into the dissolving unit, and then the solvent is introduced and the temperature is raised and stirred until the isophthalonitrile is completely dissolved, and the temperature is raised to obtain an isophthalonitrile solution;

[0006] The isophthalonitrile solution is introduced into the reaction unit and hydrogenated with hydrogen in the catalyst bed to obtain crude meta-xylylenediamine;

[0007] The crude meta-xylylenediamine is passed into a receiving unit to separate gas and liquid, and the liquid is purified by distillation to obtain meta-xylylenediamine;

[0008] The catalyst includes a main catalyst and a co-catalyst. The metal in the main catalyst includes Ni, Co and Al, and the metal in the co-catalyst includes at least one of Cr, Pt and Ru.

[0009] The total content of Ni and Co metals in the main catalyst is 60-85 wt%.

[0010] Optionally, the total content of Ni and Co metals in the main catalyst is 65-80 wt%.

[0011] The catalyst preparation method comprises the following steps: melting the metals in the main catalyst and the co-catalyst at high temperature, rapidly cooling the metal ingots, crushing the metal ingots into particles, washing them with alkali and distilled water until they are neutral, and drying them to form porous particles; and calcining and activating the porous particles.

[0012] Optionally, the porous particles have a particle size of 1-10 mm.

[0013] Optionally, the calcination temperature is 400-700°C.

[0014] Optionally, the calcination temperature is 400-600°C.

[0015] The present invention has discovered that the catalyst comprises a main catalyst and a co-catalyst. The main catalyst comprises metals including Ni, Co, and Al, and the co-catalyst comprises metals including at least one of Cr, Pt, and Ru. This not only improves the conversion rate of IPN but also enhances the selectivity of MXDA. The main catalyst and co-catalyst may form a multi-metal alloy or surface composite structure. The Ni-Pt alloy enhances the reducibility and dispersion of Ni through electronic effects, while the interaction between Cr and Al and the IPN may stabilize acidic sites, jointly optimizing the adsorption and desorption of reaction intermediates. The addition of Pt and Ru also inhibits high-temperature sintering of Ni particles. At the same time, carbon deposits are reduced by enhancing surface oxygen species, thereby maintaining the high activity and long life of the catalyst.

[0016] The solvent includes at least one of methanol and liquid ammonia.

[0017] The weight ratio of the solid isophthalonitrile to the solvent is 1:(3-9).

[0018] Optionally, the weight ratio of the solid isophthalonitrile to the solvent is 1:(4-6).

[0019] The reaction unit comprises a first-stage trickle bed reactor and a second-stage trickle bed reactor connected in series.

[0020] The hydrogenation reaction comprises: introducing an isophthalonitrile solution into a first-stage trickle bed reactor, reacting with hydrogen through a catalyst bed to obtain a reaction product, which then enters a second-stage trickle bed reactor, reacts with hydrogen through a catalyst bed to obtain crude meta-xylylenediamine.

[0021] The speed at which the isophthalonitrile solution is introduced into the reaction unit is 100-1000 g / h.

[0022] Optionally, the isophthalonitrile solution is introduced into the reaction unit at a rate of 400-1000 g / h.

[0023] The temperature of the reaction unit is 70-90° C., and the pressure is 4-7 MPa.

[0024] Optionally, the temperature of the reaction unit is 75-85° C. and the pressure is 5-6 MPa.

[0025] Beneficial effects

[0026] 1. The catalyst includes a main catalyst and a co-catalyst. The metals in the main catalyst include Ni, Co and Al, and the metals in the co-catalyst include at least one of Cr, Pt and Ru. This not only improves the conversion rate of IPN, but also improves the selectivity of MXDA.

[0027] 2. The total content of Ni and Co metals in the catalyst is 60-85 wt%, which can improve the stability of the catalyst and meet the needs of continuous production of MXDA.

[0028] 3. The reaction unit of the present invention comprises a first-stage trickle bed reactor and a second-stage trickle bed reactor connected in series, which can reduce the content of the by-product intermediate 3-cyanobenzylamine, and the selectivity of MXDA can reach 98%.

[0029] 4. The weight ratio of the solid isophthalonitrile to the solvent is 1:(3-9), and the speed of the isophthalonitrile solution passing into the reaction unit is 100-1000 g / h, and the conversion rate of IPN can reach 100%.

[0030] 5. The process of the m-phenylenediamine of the present invention is simple and can ensure stable continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a diagram of the apparatus for producing meta-xylenediamine in Example 1.

[0032] Among them, 1. dissolving unit; 2. first feed port; 3. second feed port; 4. third feed port; 5. first-stage trickle bed reactor; 6. first buffer tank; 7. second buffer tank; 8. first-stage trickle bed reactor; 9. fourth feed port; 10. gas-liquid separation tank; 11. coarse material collection tank; 12. gas outlet. DETAILED DESCRIPTION

[0033] Example 1

[0034] A process for producing m-xylylenediamine, such as Figure 1 As shown, the following steps are:

[0035] Solid isophthalonitrile is fed into the dissolving unit 1 from the first feed port 2, and then a mixed solvent of methanol and liquid ammonia (weight ratio 0.5:1) is introduced from the second feed port 3 and stirred. After the isophthalonitrile is completely dissolved, the temperature is raised to 80°C to obtain an isophthalonitrile solution;

[0036] hydrogen is introduced into the first-stage trickle bed reactor 5 from the third feed port 4, and then the isophthalonitrile solution is introduced into the first-stage trickle bed reactor 5, and reacts with the hydrogen through the catalyst bed to obtain a reaction product, which passes through the first buffer tank 6 and the second buffer tank 7 and then enters the second-stage trickle bed reactor 8, and hydrogen is introduced into the second-stage trickle bed reactor 8 from the fourth feed port 9, and reacts with the hydrogen through the catalyst bed to obtain crude meta-xylylenediamine;

[0037] The crude meta-xylylenediamine is passed into the gas-liquid separation tank 10 to separate the gas and liquid. The gas is collected through the gas outlet 12 and the liquid enters the crude material collection tank 11. It is then purified by distillation to obtain meta-xylylenediamine.

[0038] The catalyst comprises a main catalyst and a co-catalyst. The metals in the main catalyst are Ni, Co and Al, and the metals in the co-catalyst are Cr, Pt and Ru.

[0039] The raw materials for preparing the catalyst include: by weight percentage, Ni accounts for 19%, Co accounts for 19%, Al accounts for 50%, Cr accounts for 8%, Pt accounts for 1%, and Ru accounts for 3%.

[0040] The preparation method of the catalyst comprises the following steps: melting the metal in the catalyst at high temperature, rapidly cooling the metal ingot, crushing the metal ingot into 3mm particles, washing the metal ingot with alkali to remove part of Al, washing the metal ingot with distilled water until the metal ingot is neutral, and drying the metal ingot to form porous particles; and calcining the porous particles at 500°C for activation.

[0041] The prepared catalyst contains 75 wt% of Ni and Co metals in total, 24 wt% of Cr, Pt and Ru in total, and the remainder is Al.

[0042] The first buffer tank 6 and the second buffer tank 7 contain a mixed solvent of methanol and liquid ammonia.

[0043] The weight ratio of the solid isophthalonitrile to the solvent is 10:90; the speed of the isophthalonitrile solution passing into the reaction unit is 1000g / h

[0044] The temperature of the reaction unit is 80° C. and the pressure is 6 MPa.

[0045] Example 2

[0046] The specific implementation method is the same as that of Example 1; except that the weight ratio of the solid isophthalonitrile to the solvent in Example 2 is 15:85; and the speed at which the isophthalonitrile solution is introduced into the reaction unit is 667 g / h.

[0047] Example 3

[0048] The specific implementation is the same as that of Example 1; except that the weight ratio of the solid isophthalonitrile to the solvent in Example 3 is 20:80; and the speed at which the isophthalonitrile solution is introduced into the reaction unit is 500 g / h.

[0049] Example 4

[0050] The specific implementation is the same as that of Example 1; except that the weight ratio of the solid isophthalonitrile to the solvent in Example 3 is 25:75; and the speed at which the isophthalonitrile solution is introduced into the reaction unit is 400 g / h.

[0051] Comparative Example 1

[0052] The specific embodiment is the same as Example 2, except that the raw materials for preparing the catalyst in Comparative Example 1 include, by weight percentage, 40% Ni, 50% Al, 6% Cr, 1% Pt, and 3% Ru. The prepared catalyst has a Ni content of 75% by weight, a total of Cr, Pt, and Ru of 24% by weight, and the balance being Al.

[0053] Comparative Example 2

[0054] The specific embodiment is the same as Example 2, except that the raw materials for preparing the catalyst in Comparative Example 2 include, by weight, 40% Co, 50% Al, 6% Cr, 1% Pt, and 3% Ru. The prepared catalyst has a Co content of 75% by weight, a total of Cr, Pt, and Ru of 24% by weight, and the balance being Al.

[0055] Performance testing methods

[0056] The IPN concentration of the first-stage trickle bed reactor discharge, the MXDA concentration of the first-stage trickle bed reactor discharge, the IPN concentration of the second-stage trickle bed reactor discharge, the MXDA concentration of the second-stage trickle bed reactor discharge, the overall IPN conversion rate and the MXDA selectivity in the detection examples and comparative examples are listed in Table 1.

[0057] Performance test data

[0058] Table 1

[0059]

[0060] As can be seen from Table 1, in the hydrogenation reaction of isophthalonitrile using a nickel-cobalt alloy catalyst, isophthalonitrile undergoes hydrogenation reaction in the first-stage trickle bed reactor to produce meta-xylylenediamine, with only a small amount remaining. No isophthalonitrile is present in the material exiting the second-stage reactor, indicating that after passing through the two-stage reactor, the isophthalonitrile has been completely reacted, with a conversion rate of 100%, and the selectivity of the product meta-xylylenediamine is also above 98%.

[0061] When the IPN feed rate is the same at 100 g / h, there are some differences in the catalytic hydrogenation reaction capacity after the two-stage reactor. The higher the IPN concentration, the weaker the hydrogenation reaction capacity. Therefore, in the process of producing meta-xylylenediamine by hydrogenation of isophthalonitrile, it is also very important to control the IPN feed concentration.

[0062] Comparing the nickel skeleton catalyst (Comparative Example 1) and the cobalt skeleton catalyst (Comparative Example 2), the nickel skeleton catalyst has higher activity, but poor selectivity for the target product MXDA. Although the cobalt skeleton catalyst has poor activity, it has high selectivity for MXDA. In the embodiment, nickel and cobalt are mixed to prepare a nickel-cobalt alloy catalyst, which not only improves the conversion rate of IPN, but also improves the selectivity of MXDA, and is suitable for the catalytic hydrogenation of isophthalonitrile to prepare meta-xylylenediamine.

Claims

1. A process for producing meta-xylylenediamine, characterized in that: The following steps are involved: Solid isophthalonitrile is put into the dissolving unit, and then the solvent is introduced and stirred until the isophthalonitrile is completely dissolved, and the temperature is raised to obtain an isophthalonitrile solution; The isophthalonitrile solution is introduced into the reaction unit and hydrogenated with hydrogen in the catalyst bed to obtain crude meta-xylylenediamine; The crude meta-xylylenediamine is passed into a receiving unit to separate gas and liquid, and the liquid is purified by distillation to obtain meta-xylylenediamine; The catalyst includes a main catalyst and a co-catalyst. The metal in the main catalyst includes Ni, Co and Al, and the metal in the co-catalyst includes at least one of Cr, Pt and Ru. The preparation process of the catalyst includes calcination.

2. The process for producing meta-xylylenediamine according to claim 1, wherein The total content of Ni and Co in the main catalyst is 60-85 wt%.

3. The process for producing meta-xylylenediamine according to claim 2, wherein: The solvents include methanol and liquid ammonia.

4. The process for producing meta-xylylenediamine according to claim 2, wherein: The weight ratio of the solid isophthalonitrile to the solvent is 1:(3-9).

5. The process for producing meta-xylylenediamine according to claim 1, wherein: The reaction unit comprises a first-stage trickle bed reactor and a second-stage trickle bed reactor connected in series.

6. The process for producing meta-xylylenediamine according to claim 5, wherein: The hydrogenation reaction comprises: introducing an isophthalonitrile solution into a first-stage trickle bed reactor, reacting with hydrogen through a catalyst bed to obtain a reaction product, which then enters a second-stage trickle bed reactor, reacts with hydrogen through a catalyst bed to obtain crude meta-xylylenediamine.

7. The process for producing meta-xylylenediamine according to claim 1, wherein: The speed at which the isophthalonitrile solution is introduced into the reaction unit is 100-1000 g / h.

8. The process for producing meta-xylylenediamine according to claim 7, wherein: The speed at which the isophthalonitrile solution is introduced into the reaction unit is 400-1000 g / h.

9. The process for producing meta-xylylenediamine according to claim 8, characterized in that: The temperature of the reaction unit is 70-90° C., and the pressure is 4-7 MPa.

10. The process for producing meta-xylylenediamine according to claim 9, characterized in that: The temperature of the reaction unit is 75-85° C., and the pressure is 5-6 MPa.

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