A process for separation and purification of o-phenylenediamine

Abstract

The invention discloses a kind of o-phenylenediamine separation and purification process, belongs to the technical field of o-phenylenediamine separation and purification, comprises the following steps: add water, skeleton nickel catalyst, o-nitroaniline into reactor, stir and heat up, pass hydrogen into reactor to react, react after 6h, when the pressure in the reactor does not drop, stand still for 30-45min, obtain material mixture, be transported to crystallizer for crystallization, and be transported to product tank after crystallization melts;Non-crystallized solution is carried out secondary crystallization by crystallizer, and crystallization product two is melted and enters product tank;Non-crystallized solution two enters precipitation tower one, precipitation tower two in turn, removes hydrogen and water in solution twice, and finally removes liquid B and continues to return to crystallizer. The product o-phenylenediamine obtained by the process of the present invention completely removes solvent water, and can directly enter the next process process, and the process flow is simple, and skeleton nickel catalyst can be repeatedly applied.

Description

Technical Field

[0001] The invention belongs to the technical field of separation and purification of o-phenylenediamine, and in particular relates to a process for separation and purification of o-phenylenediamine. Background Art

[0002] O-phenylenediamine is an aromatic amine with the molecular formula C6H4(NH2)2. It is an important fine chemical intermediate with the following main uses: as a pesticide intermediate, a dye intermediate; an intermediate for synthesizing various heterocyclic rings and for making antioxidants; and as an intermediate for medicines and rubber developers.

[0003] At present, there are three main methods for the synthesis of o-phenylenediamine: iron powder reduction, sodium sulfide reduction, and catalytic hydrogenation. Although the production process of the first two reduction methods is mature, they produce a large amount of toxic wastewater and waste residue, which is difficult to post-process and causes serious pollution. The catalytic hydrogenation method is a green process with the advantages of good product quality, low cost, less three wastes, and easy processing. However, a relatively large problem is the residence time. If the residence time is too long, side reactions will occur to generate tar, and if the residence time is too short, the reaction will be incomplete. The adjustment of production load will cause large fluctuations in the residence time. For this reason, it is necessary to adjust the amount of solvent (water) used, and rely on the amount of solvent to control the residence time; however, if the amount of solvent added is too large, the desolventization is not thorough enough and cannot enter the next process. Summary of the invention

[0004] The object of the present invention is to provide a separation and purification process of o-phenylenediamine to solve the problem that o-phenylenediamine synthesized by catalytic hydrogenation cannot be completely desolvated.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A process for separating and purifying o-phenylenediamine comprises the following steps:

[0007] Step 1, add water, skeleton nickel catalyst, and o-nitroaniline into a reactor, stir and heat, introduce hydrogen into the reactor to react, react for 6 hours, wait for the pressure in the reactor to not drop, stand for 30-45 minutes, wait for the skeleton nickel catalyst to settle to the bottom of the reactor, and obtain a material mixture;

[0008] The catalytic hydrogenation reaction of o-nitroaniline produces o-phenylenediamine, and the reaction formula is as follows:

[0009]

[0010] Step 2, transporting the material mixture to a crystallizer through a raw material pump for crystallization to obtain a crystallized product 1 (o-phenylenediamine crystals) and an uncrystallized solution 1;

[0011] Step 3, after melting the crystallized product 1, transport it to the product tank; transport the uncrystallized solution 1 to the solvent receiving tank 1, and then return it to the crystallizer through the concentrated feed pump for secondary crystallization to obtain the crystallized product 2 (o-phenylenediamine crystals) and the uncrystallized solution 2;

[0012] Step 4, melt the crystallized product 2 and enter the product tank; the uncrystallized solution 2 enters the desolventizing tower 1, firstly, the hydrogen in the uncrystallized solution 2 is extracted by a vacuum pump, and then the water in the uncrystallized solution 2 is removed to obtain the desolventized solution A, and the water enters the solvent receiving tank 2;

[0013] Step 5, the desolvent A enters the second desolventizing tower, and the residual hydrogen in the desolvent A is first extracted by a vacuum pump, and then the water in the desolvent A is removed for a second time to obtain the desolvent B, and the desolvent B returns to the crystallizer, and the water enters the solvent receiving tank 2, completing a separation and purification process of o-phenylenediamine.

[0014] As a further solution of the present invention, the volume of water added in step 1 is 40-60% of the volume of the reactor.

[0015] As a further embodiment of the present invention, the usage ratio of water, skeleton nickel catalyst and o-nitroaniline in step 1 is 160-550 mL: 1.5-5 g: 75-250 g.

[0016] As a further embodiment of the present invention, the reaction temperature in step 1 is 90-120° C., and the reaction pressure is 1.3-2.0 MPa.

[0017] Beneficial effects of the present invention:

[0018] The method comprises the following steps: firstly allowing a mixed liquid of materials obtained by reaction to enter a crystallizer for crystallization to obtain a product o-phenylenediamine, and then returning an uncrystallized solution 1 to the crystallizer for secondary crystallization, and then passing an uncrystallized solution 2 through a first desolventizing tower and a second desolventizing tower in sequence to remove hydrogen and water in the solution, and finally removing the solution B and returning it to the crystallizer. The o-phenylenediamine product obtained by the o-phenylenediamine separation and purification process of the invention completely removes solvent water and can directly enter the next process for treatment, the process flow is simple, and the skeleton nickel catalyst can be repeatedly used. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 The present invention is a schematic diagram of a process for separating and purifying o-phenylenediamine according to Example 1.

[0021] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0022] 1. Reactor; 2. Raw material pump; 3. Crystallizer; 4. Product tank; 5. Solvent receiving tank 1; 6. Concentration feed pump; 7. Desolventizing tower 1; 8. Vacuum pump; 9. Solvent receiving tank 2; 10. Desolventizing tower 2. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] See also Figure 1 As shown, a process for separating and purifying o-phenylenediamine comprises the following steps:

[0026] Step 1: first add 160 mL of water (the volume of water added is 40% of the volume of the reactor 1) to the reactor 1, then add 1.5 g of skeleton nickel catalyst and 75 g of o-nitroaniline, stir and heat to 90 ° C, introduce hydrogen into the reactor 1 until the reaction pressure reaches 1.3 MPa for reaction, react for 6 hours, wait for the pressure in the reactor 1 to not drop, stand for 30 min, wait for the skeleton nickel catalyst to settle to the bottom of the reactor, and obtain a material mixture;

[0027] Step 2: transporting the material mixture to the crystallizer 3 through the raw material pump 2 for crystallization to obtain a crystallized product 1 (o-phenylenediamine crystals) and an uncrystallized solution 1;

[0028] Step 3, after melting the crystallized product 1, transport it to the product tank 4; transport the uncrystallized solution 1 to the solvent receiving tank 1 5, and then return it to the crystallizer 3 through the concentration feed pump 6 for secondary crystallization to obtain the crystallized product 2 (o-phenylenediamine crystals) and the uncrystallized solution 2;

[0029] Step 4, melt the crystallized product 2 and enter the product tank 4; the uncrystallized solution 2 enters the desolventizing tower 1 7, firstly, the hydrogen in the uncrystallized solution 2 is extracted by the vacuum pump 8, and then the water in the uncrystallized solution 2 is removed to obtain the desolventized solution A, and the water enters the solvent receiving tank 2 9;

[0030] Step 5, the desolvent A enters the second desolventizing tower 10, and the residual hydrogen in the desolvent A is first extracted by the vacuum pump 8, and then the water in the desolvent A is removed for a second time to obtain the desolvent B, and the desolvent B returns to the crystallizer 3, and the water enters the solvent receiving tank 2 9, completing a separation and purification process of o-phenylenediamine.

[0031] Example 2

[0032] A process for separating and purifying o-phenylenediamine comprises the following steps:

[0033] Step 1, first add 550mL of water into the reactor 1 (the volume of water added is 60% of the volume of the reactor 1), then add 5g of skeleton nickel catalyst and 250g of o-nitroaniline, stir and heat to 120°C, introduce hydrogen into the reactor 1 until the reaction pressure reaches 2.0MPa for reaction, react for 6h, wait for the pressure in the reactor 1 to not drop, stand for 45min, wait for the skeleton nickel catalyst to settle to the bottom of the reactor, and obtain a material mixture;

[0034] Step 2: transporting the material mixture to the crystallizer 3 through the raw material pump 2 for crystallization to obtain a crystallized product 1 (o-phenylenediamine crystals) and an uncrystallized solution 1;

[0035] Step 3, after melting the crystallized product 1, transport it to the product tank 4; transport the uncrystallized solution 1 to the solvent receiving tank 1 5, and then return it to the crystallizer 3 through the concentration feed pump 6 for secondary crystallization to obtain the crystallized product 2 (o-phenylenediamine crystals) and the uncrystallized solution 2;

[0036] Step 4, melt the crystallized product 2 and enter the product tank 4; the uncrystallized solution 2 enters the desolventizing tower 1 7, firstly, the hydrogen in the uncrystallized solution 2 is extracted by the vacuum pump 8, and then the water in the uncrystallized solution 2 is removed to obtain the desolventized solution A, and the water enters the solvent receiving tank 2 9;

[0037] Step 5, the desolvent A enters the second desolventizing tower 10, and the residual hydrogen in the desolvent A is first extracted by the vacuum pump 8, and then the water in the desolvent A is removed for a second time to obtain the desolvent B, and the desolvent B returns to the crystallizer 3, and the water enters the solvent receiving tank 2 9, completing a separation and purification process of o-phenylenediamine.

[0038] Example 3

[0039] A process for separating and purifying o-phenylenediamine comprises the following steps:

[0040] Step 1, first add 355mL of water into the reactor 1 (the volume of water added is 50% of the volume of the reactor 1), then add 3.5g of skeleton nickel catalyst and 325g of o-nitroaniline, stir and heat to 105°C, introduce hydrogen into the reactor 1 until the reaction pressure reaches 1.7MPa for reaction, react for 6h, wait until the pressure in the reactor 1 does not drop, stand for 37min, wait for the skeleton nickel catalyst to settle to the bottom of the reactor, and obtain a material mixture;

[0041] Step 2: transporting the material mixture to the crystallizer 3 through the raw material pump 2 for crystallization to obtain a crystallized product 1 (o-phenylenediamine crystals) and an uncrystallized solution 1;

[0042] Step 3, after melting the crystallized product 1, transport it to the product tank 4; transport the uncrystallized solution 1 to the solvent receiving tank 1 5, and then return it to the crystallizer 3 through the concentration feed pump 6 for secondary crystallization to obtain the crystallized product 2 (o-phenylenediamine crystals) and the uncrystallized solution 2;

[0043] Step 4, melt the crystallized product 2 and enter the product tank 4; the uncrystallized solution 2 enters the desolventizing tower 1 7, firstly, the hydrogen in the uncrystallized solution 2 is extracted by the vacuum pump 8, and then the water in the uncrystallized solution 2 is removed to obtain the desolventized solution A, and the water enters the solvent receiving tank 2 9;

[0044] Step 5, the desolvent A enters the second desolventizing tower 10, and the residual hydrogen in the desolvent A is first extracted by the vacuum pump 8, and then the water in the desolvent A is removed for a second time to obtain the desolvent B, and the desolvent B returns to the crystallizer 3, and the water enters the solvent receiving tank 2 9, completing a separation and purification process of o-phenylenediamine.

[0045] Comparative Example 1

[0046] A process for separating and purifying o-phenylenediamine comprises the following steps:

[0047] Step 1: first add 160 mL of water (the volume of water added is 40% of the volume of the reactor 1) to the reactor 1, then add 1.5 g of skeleton nickel catalyst and 75 g of o-nitroaniline, stir and heat to 90 ° C, introduce hydrogen into the reactor 1 until the reaction pressure reaches 1.3 MPa for reaction, react for 6 hours, wait for the pressure in the reactor 1 to not drop, stand for 30 min, wait for the skeleton nickel catalyst to settle to the bottom of the reactor, and obtain a material mixture;

[0048] Step 2: transporting the material mixture to the crystallizer 3 through the raw material pump 2 for crystallization to obtain a crystallized product 1 (o-phenylenediamine crystals) and an uncrystallized solution 1;

[0049] Step 3, after melting the crystallized product 1, transport it to the product tank 4; transport the uncrystallized solution 1 to the solvent receiving tank 1 5, and then return it to the crystallizer 3 through the concentration feed pump 6 for secondary crystallization to obtain the crystallized product 2 (o-phenylenediamine crystals) and the uncrystallized solution 2;

[0050] Step 4: melt the crystallized product 2 and enter the product tank 4; the uncrystallized solution 2 enters the desolventizing tower 1 7, firstly, the hydrogen in the uncrystallized solution 2 is extracted by the vacuum pump 8, and then the water in the uncrystallized solution 2 is removed to obtain the desolventized solution A, and the desolventized solution A returns to the crystallizer 3, and the water enters the solvent receiving tank 2 9, thereby completing a process for separating and purifying o-phenylenediamine.

[0051] Comparative Example 2

[0052] A process for separating and purifying o-phenylenediamine comprises the following steps:

[0053] Step 1, first add 355mL of water into the reactor 1 (the volume of water added is 50% of the volume of the reactor 1), then add 3.5g of skeleton nickel catalyst and 325g of o-nitroaniline, stir and heat to 105°C, introduce hydrogen into the reactor 1 until the reaction pressure reaches 1.7MPa for reaction, react for 6h, wait until the pressure in the reactor 1 does not drop, stand for 37min, wait for the skeleton nickel catalyst to settle to the bottom of the reactor, and obtain a material mixture;

[0054] Step 2: transporting the material mixture to the crystallizer 3 through the raw material pump 2 for crystallization to obtain a crystallized product 1 (o-phenylenediamine crystals) and an uncrystallized solution 1;

[0055] Step 3, after melting the crystallized product 1, transport it to the product tank 4; transport the uncrystallized solution 1 to the solvent receiving tank 1 5, and then return it to the crystallizer 3 through the concentration feed pump 6 for secondary crystallization to obtain the crystallized product 2 (o-phenylenediamine crystals) and the uncrystallized solution 2;

[0056] Step 4: melt the crystallized product 2 and put it into the product tank 4, thus completing a separation and purification process of o-phenylenediamine.

[0057] Comparative Example 3

[0058] A process for separating and purifying o-phenylenediamine comprises the following steps:

[0059] Step 1: first add 160 mL of water (the volume of water added is 40% of the volume of the reactor 1) to the reactor 1, then add 1.5 g of skeleton nickel catalyst and 75 g of o-nitroaniline, stir and heat to 90 ° C, introduce hydrogen into the reactor 1 until the reaction pressure reaches 1.3 MPa for reaction, react for 6 hours, wait for the pressure in the reactor 1 to not drop, stand for 30 min, wait for the skeleton nickel catalyst to settle to the bottom of the reactor, and obtain a material mixture;

[0060] Step 2: transporting the material mixture to the crystallizer 3 through the raw material pump 2 for crystallization to obtain a crystallized product 1 (o-phenylenediamine crystals) and an uncrystallized solution 1;

[0061] Step 3, melt the crystallized material 1 and enter the product tank 4; the uncrystallized solution 1 enters the desolventizing tower 1 7, firstly, the hydrogen in the uncrystallized solution 2 is extracted by the vacuum pump 8, and then the water in the uncrystallized solution 2 is removed to obtain the desolventized solution A, and the water enters the solvent receiving tank 2 9;

[0062] Step 4, the desolvent A enters the second desolventizing tower 10, and the residual hydrogen in the desolvent A is first extracted by the vacuum pump 8, and then the water in the desolvent A is removed for a second time to obtain the desolvent B, and the desolvent B returns to the crystallizer 3, and the water enters the solvent receiving tank 2 9, completing a separation and purification process of o-phenylenediamine.

[0063] The performance of o-phenylenediamine obtained by separation and purification of Example 1-3 and Comparative Example 1-3 was tested:

[0064] (1) Determination of moisture content:

[0065] The steps are as follows: Step ① Pipette 25 mL of anhydrous methanol reagent into the reactor, cover the bottle with a stopper, turn on the power supply, start the electromagnetic stirrer, and use Karl Fischer reagent to titrate the trace water in the solution until the current reading produces a large deflection and remains unchanged for 1 minute as the endpoint.

[0066] Step ② Add 10 μL of water to the reactor, cover the bottle with a stopper, and drip Karl Fischer reagent until the current reading remains at the endpoint value of the blank test, and remain unchanged for 1 min as the endpoint, and record the reagent volume V.

[0067] Step ③ Use a pipette to add 5 ml of glacial acetic acid to the reactor, cover the bottle stopper, drip Karl Fischer reagent until the current reading stays at the value of the end point in the blank test, and keep it unchanged for 1min as the end point, add 0.2g of the product to be tested o-phenylenediamine (accurate to 0.0002 grams) to the reactor, cover the bottle stopper, drip Karl Fischer reagent until the current reading stays at the value of the end point in the blank test, and keep it unchanged for 1min as the end point, record the reagent dosage V1; and calculate the water content according to the following formula and record it:

[0068] Water content (%) = (V1-V) / 0.2g×100%;

[0069] (2) Yield determination:

[0070] The mass of the obtained product o-phenylenediamine was weighed respectively and the yield was calculated according to the following formula:

[0071] Yield (%) = (actual) amount of o-phenylenediamine produced / theoretical amount of o-phenylenediamine produced × 100%.

[0072] The results are shown in Table 1.

[0073] Table 1

[0074] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Moisture content / % 100 100 100 100 100 100 Yield / % 95.5 96.1 95.8 88.3 47.6 94.3

[0075] It can be seen from Table 1 that the o-phenylenediamine product separated and purified in Examples 1-3 completely removes solvent water, and the o-phenylenediamine separation and purification process in Examples 1-3 has a higher product yield than the o-phenylenediamine separation and purification process in Comparative Examples 1-3, and the yield is stable.

[0076] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0077] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for separation and purification of o-phenylenediamine, characterized in that: The steps include: Step 1, add water, skeleton nickel catalyst, and o-nitroaniline into a reaction kettle (1), stir and heat, introduce hydrogen into the reaction kettle (1) to react, react for 6 hours, and when the pressure in the reaction kettle (1) does not drop, let it stand for 30-45 minutes to obtain a material mixed liquid; Step 2: transporting the material mixture to a crystallizer (3) through a raw material pump (2) for crystallization to obtain a crystallized product 1 and an uncrystallized solution 1; Step 3, after melting the crystallized product 1, transport it to the product tank (4); transport the uncrystallized solution 1 to the solvent receiving tank 1 (5), and then return it to the crystallizer (3) through the concentration feed pump (6) for secondary crystallization, thereby obtaining the crystallized product 2 and the uncrystallized solution 2; Step 4: melt the crystallized product 2 and enter the product tank (4); the uncrystallized solution 2 enters the desolventizing tower 1 (7), firstly, the hydrogen in the uncrystallized solution 2 is extracted by a vacuum pump (8), and then the water in the uncrystallized solution 2 is removed to obtain a desolventized solution A, and the water enters the solvent receiving tank 2 (9); Step 5, the desolvent A enters the second desolventizing tower (10), firstly, the residual hydrogen in the desolvent A is extracted by the vacuum pump (8), and then the water in the desolvent A is removed for a second time to obtain the desolvent B, and the desolvent B returns to the crystallizer (3), and the water enters the second solvent receiving tank (9), thereby completing a process for separating and purifying o-phenylenediamine.

2. A process for separation and purification of o-phenylenediamine according to claim 1, characterized in that: The volume of water added in step 1 is 40-60% of the volume of the reaction kettle (1).

3. A process for separation and purification of o-phenylenediamine according to claim 1, characterized in that: The usage ratio of water, skeleton nickel catalyst and o-nitroaniline in step 1 is 160-550 mL: 1.5-5 g: 75-250 g.

4. A process for separation and purification of o-phenylenediamine according to claim 1, characterized in that: The reaction temperature is 90-120° C., and the reaction pressure is 1.3-2.0 MPa.

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