A production process for the catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine

Abstract

The present invention relates to a production process for synthesizing hexamethylenediamine by catalytic hydrogenation of adiponitrile. The process comprises the following steps: 1) preparing a catalyst precursor; 2) calcining the catalyst precursor to obtain a catalyst; 3) catalytic hydrogenation of adiponitrile under the condition of the catalyst to synthesize crude hexamethylenediamine; 4) separating hexamethylenediamine from the discharge of a fluidized bed reactor containing crude hexamethylenediamine. The present invention uses Ni(NO3)2 and / or Mg(NO3)2 as main raw materials, doped with transition metal oxides, and then performs ultrasonic adsorption using Al2O3 as a catalyst carrier to load Ni(NO3)2 and / or Mg(NO3)2 and transition metal oxides on Al2O3, and obtains a catalyst through high-temperature calcination. The doping of transition metal oxides can improve the basicity of the catalyst, eliminating the need to add a strong basic co-catalyst in the catalytic reaction stage, reducing by-product formation. Moreover, it increases the specific surface area of the catalyst, thereby reducing the adsorption of the reaction product hexamethylenediamine on the catalyst, extending the service life of the catalyst, and saving the energy consumption for catalyst regeneration.

Description

Technical Field

[0001] The present invention relates to a production process for the catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine, belonging to the technical field of organic chemical industry. Background Art

[0002] 1,6-Hexamethylenediamine is an important intermediate in the chemical production process. Amino groups exist at both ends of its carbon chain, and it can undergo polycondensation reactions with groups such as carboxyl groups and acyl halides. The main use of hexamethylenediamine is to react with adipic acid to produce nylon 66 products, react with sebacic acid to produce nylon 610 products, make various nylon resins, nylon fibers and engineering plastic products, and can also synthesize curing agents, organic crosslinking agents, etc. of diisocyanates, epoxy resins or urea formaldehyde resins. Its downstream products are widely used in the electrical field, aerospace field and automotive field.

[0003] Currently, the synthesis processes of hexamethylenediamine mainly include adiponitrile hydrogenation method, caprolactam amination hydrogenation method, hexanediol amination method, adipaldehyde amination hydrogenation method, etc. Compared with other several process technologies, the adiponitrile hydrogenation method for producing hexamethylenediamine has mild reaction conditions, requires lower temperature and pressure, and has a higher yield, which is more in line with the requirements of industrial large-scale production.

[0004] Chinese patent document CN114249656A discloses a preparation method of hexamethylenediamine. Adiponitrile and hydrogen are subjected to a hydrogenation reaction under the conditions of 90 - 100 °C and 4 - 6 MPa, using a 3wt% - 5wt% Raney cobalt catalyst and 3wt% - 5wt% of LiOH or NaOH as a co-catalyst. This patent requires adding a strong alkaline co-catalyst in the catalytic reaction stage, which not only increases the cost and process but also easily generates by-products.

[0005] US patent document US3821305A discloses a method for continuously synthesizing hexamethylenediamine in a gas-liquid-solid three-phase fluidized bed reactor. This method uses a 12% Raney nickel catalyst with an alkali content of 0.6%, a reaction temperature of 75 °C, and a pressure of 3 MP, and the yield of hexamethylenediamine can reach 99%. Although a relatively high yield of hexamethylenediamine can be obtained, the catalyst dosage is large and the cost is high. And traditional fluidized bed reactors have disadvantages such as inconvenient replacement and regeneration of catalysts, requiring reactor shutdown and disassembly for catalyst replacement; cannot use fine particle catalyst powders; complex reactor structure and high construction cost; large wear on the reactor by the fluidized bed, etc.

[0006] Chinese patent document CN114436853A discloses a method for hydrogenating adiponitrile to hexamethylenediamine. Adiponitrile, hydrogen and ammonia are subjected to a hydrogenation reaction under the conditions of 60 - 130 °C and 1.5 - 12 MPa, using a carbon-supported Raney alloy catalyst. This method requires continuous circulation reaction and needs to add ammonia that is not required in the final product to the reaction system.

[0007] Therefore, it is a technical problem that urgently needs to be solved by those skilled in the art to invent a production process with high raw material conversion rate, mild reaction conditions, economic environmental protection and continuous production. Summary of the Invention

[0008] In view of the deficiencies of the prior art, the present invention provides a production process for catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine. This production process has mild reaction conditions and can achieve continuous production.

[0009] The technical solution of the present invention is as follows:

[0010] A production process for catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine, comprising the following steps:

[0011] 1) Add Ni(NO3)2 and / or Mg(NO3)2 to pure water to make the concentration of the Ni(NO3)2 and / or Mg(NO3)2 aqueous solution reach 50-75%; then add a transition metal oxide to obtain a mixed solution; then drop the mixed solution into an Al2O3 catalyst support, perform ultrasonic adsorption for 1-3 h, and after filtration and drying, obtain a catalyst precursor;

[0012] 2) Place the catalyst precursor in an O2 / Ar mixed gas and calcine it at 500-750 °C for 5-10 h, and after grinding, obtain a catalyst;

[0013] 3) Mix adiponitrile and an organic solution evenly to obtain an adiponitrile solution; pack the catalyst into the top of a fluidized bed reactor, then introduce the adiponitrile solution into the fluidized bed reactor, introduce hydrogen, and control the liquid-phase volume space velocity of the adiponitrile solution to be 0.5-10 h -1 , and the gas-phase volume space velocity of hydrogen to be 5-100 h -1 , and react adiponitrile and hydrogen with the catalyst at a temperature of 70-140 °C and a pressure of 2-12 MPa for 24-240 h to obtain crude hexamethylenediamine;

[0014] 4) First, perform solid-liquid separation on the discharge of the fluidized bed reactor containing crude hexamethylenediamine. The obtained solid is the catalyst that has participated in the reaction. After separation, it is calcined in an O2 / Ar mixed gas and reused; the obtained liquid is subjected to rectification separation to obtain hexamethylenediamine.

[0015] Preferably according to the present invention, in step 1), the concentration of the Ni(NO3)2 and / or Mg(NO3)2 aqueous solution is 50-60%.

[0016] Preferably according to the present invention, in step 1), the time of ultrasonic adsorption is 1 h, the drying temperature is 100-120 °C, and the drying time is 3-5 h.

[0017] Preferably according to the present invention, in step 1), the transition metal oxide is a metal oxide of Cu and / or Co, and the mass fraction of Cu and / or Co in the catalyst is 0% to 5%.

[0018] Preferably according to the present invention, in step 1), the Al2O3 catalyst support is a nanoscale Al2O3 catalyst support, and the mass ratio of the Al2O3 catalyst support to Ni(NO3)2 and / or Mg(NO3)2 is (3 - 4):5.

[0019] Preferably according to the present invention, in step 2), the calcination temperature is 600 - 700 °C, and the calcination time is 8 - 10 h.

[0020] Preferably according to the present invention, in step 2), the volume ratio of O2 to Ar in the mixed gas is 2:3, and the volume space velocity of the mixed gas is 10 - 50 h -1 。

[0021] Preferably according to the present invention, in step 3), the specific structure of the fluidized bed reactor is as follows:

[0022] The fluidized bed reactor includes a hexamethylenediamine reactor. A catalyst distributor is provided at the top of the hexamethylenediamine reactor, a catalyst particle settler is provided at the bottom, a solid-liquid separator is provided on the side, and a feeding device is provided in the center;

[0023] The catalyst distributor and the catalyst particle settler are connected by a pipeline, so that the hexamethylenediamine reactor, the catalyst distributor and the catalyst particle settler form a closed loop; a catalyst calcination furnace is also provided on this pipeline;

[0024] The hexamethylenediamine reactor is connected to the solid-liquid separator by a pipeline, and the solid-liquid separator is also connected to a reaction material discharge pipe; the solid-liquid separator is connected to the catalyst particle settler by a pipeline; the hexamethylenediamine reactor, the solid-liquid separator and the catalyst particle settler form a closed loop;

[0025] One end of the feeding device is a liquid feeding port, the other end is a gas feeding port, and a fence-shaped reaction material distributor is provided in the center.

[0026] Preferably according to the present invention, in step 3), the mass concentration of adiponitrile in the adiponitrile solution is 20 - 50 wt%, and the organic solvent is ethanol.

[0027] Preferably according to the present invention, in step 3), the reaction temperature is 100 - 120 °C, and the reaction pressure is 3 - 7 MPa.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. The present invention uses Ni(NO3)2 and / or Mg(NO3)2 as the main raw materials, dopes transition metal oxides, and then performs ultrasonic adsorption with Al2O3 as the catalyst support, loading Ni(NO3)2 and / or Mg(NO3)2 and transition metal oxides on Al2O3, and obtaining the catalyst through high-temperature calcination. The doping of transition metal oxides can improve the basicity of the catalyst, so that there is no need to add a strong basic co-catalyst in the catalytic reaction stage, which can reduce the generation of by-products. And the simultaneously doped transition metal oxides can interact with Ni nanoparticles, increase the specific surface area of the catalyst, and thus reduce the adsorption of the reaction product hexamethylenediamine on the catalyst, which can extend the service life of the catalyst and save the energy consumption for catalyst regeneration.

[0030] 2. The present invention uses a fluidized bed reactor filled with the catalyst uniformly for the reaction. Compared with a batch reactor, it can realize a continuous production process, avoid the quality difference problem of products between batches in the batch method, and has a high level of automation in the process. Compared with a fixed bed reactor, it can realize the catalyst recycling and regeneration during the production process, truly achieving continuous production; and the same weight of catalyst has a larger specific surface area, making the catalyst and reaction materials contact more fully.

[0031] 3. After the catalyst prepared by the present invention is combined with the fluidized bed reactor, the conversion rate of adiponitrile remains above 97.5% after 240 h of reaction, and the selectivity of hexamethylenediamine remains above 96% after 240 h of reaction.

[0032] 4. The reaction conditions of the present invention are relatively mild, the energy consumption in the production process is less, and the yield of the obtained product is high. It is more suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of the fluidized bed reactor of the present invention.

[0034] In the figure: 1 - hexamethylenediamine reactor, 2 - catalyst distributor, 3 - catalyst particle settler, 4 - solid-liquid separator, 5 - catalyst calcination furnace, 6 - reaction material discharge pipe, 7 - liquid feed inlet, 8 - gas feed inlet, 9 - reaction material distributor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] The raw materials, compounds, methods, and devices not described in detail in the present invention are all prior arts and will not be elaborated further.

[0037] To further understand the present invention, the following is a detailed description of a production process for catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine provided by the present invention in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0038] Example 1

[0039] A production process for catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine includes the following steps:

[0040] 1) Add 50 g of Ni(NO3)2 to 50 g of pure water to make the concentration of the Ni(NO3)2 aqueous solution reach 50%. Then, drop the Ni(NO3)2 aqueous solution into 30 g of a nanoscale Al2O3 catalyst support, perform ultrasonic adsorption for 2 h, filter, put it into a small meshing machine for meshing, and dry it in an oven at 100 °C for 3 h to obtain a catalyst precursor.

[0041] 2) Place the catalyst precursor in an O2 / Ar mixed gas and calcine it at 600 °C for 8 h. After grinding, obtain the catalyst.

[0042] 3) Mix 20 g of adiponitrile and 70 g of ethanol evenly to obtain an adiponitrile ethanol solution; load the catalyst into the top of a fluidized bed reactor, and then introduce the adiponitrile ethanol solution into the fluidized bed reactor at a flow rate of 40 mL / h, and introduce high-pressure hydrogen into the fluidized bed reactor at a flow rate of 1 L / h. Control the liquid-phase volume space velocity of the adiponitrile ethanol solution to be 2 h -1 , and the gas-phase volume space velocity of hydrogen to be 20 h -1 , and make adiponitrile and hydrogen react with the catalyst at a temperature of 120 °C and a pressure of 7 MPa for 48 h to obtain crude hexamethylenediamine.

[0043] 4) First, perform solid-liquid separation on the effluent from the fluidized bed reactor containing crude hexamethylenediamine. The obtained solid is the catalyst that has participated in the reaction. After separation, calcine it in an O2 / Ar mixed gas and reuse it; perform rectification separation on the obtained liquid to obtain hexamethylenediamine.

[0044] In step 3), the specific structure of the fluidized bed reactor is as follows:

[0045] The floating bed reactor includes a hexamethylenediamine reactor 1. A catalyst distributor 2 is provided at the top of the hexamethylenediamine reactor 1, a catalyst particle settler 3 is provided at the bottom, a solid-liquid separator 4 is provided on the side, and a feeding device is provided in the center. The catalyst distributor 2 and the catalyst particle settler 3 are connected by a pipeline, so that the hexamethylenediamine reactor 1, the catalyst distributor 2 and the catalyst particle settler 3 form a closed loop. A catalyst calcination furnace 5 is also provided on this pipeline. The hexamethylenediamine reactor 1 is connected to the solid-liquid separator 4 by a pipeline, and the solid-liquid separator 4 is also connected to a reaction material discharge pipe 6. The solid-liquid separator 4 is connected to the catalyst particle settler 3 by a pipeline. The hexamethylenediamine reactor 1, the solid-liquid separator 4 and the catalyst particle settler 3 form a closed loop. One end of the feeding device is a liquid feeding port 7, the other end is a gas feeding port 8, and a fence-shaped reaction material distributor 9 is provided in the center.

[0046] In specific use, a metering pump is used to add adiponitrile ethanol solution into the hexamethylenediamine reactor 1 through the liquid feeding port 7, add hydrogen into the hexamethylenediamine reactor 1 through the gas feeding port 8, add a catalyst into the hexamethylenediamine reactor 1 through the catalyst distributor 2, and adjust the temperature and pressure to carry out the hexamethylenediamine synthesis reaction. After the reaction is completed, a part of the catalyst naturally settles into the catalyst particle settler 3; another part is mixed into the floating bed reactor discharge containing crude hexamethylenediamine. After the floating bed reactor discharge containing crude hexamethylenediamine is treated by the solid-liquid separator 4, the separated catalyst and the catalyst collected by the catalyst particle settler 3 are transported to the catalyst calcination furnace 5 for calcination and reused; the separated liquid is discharged from the reaction material discharge pipe 6 and, after rectification and separation, hexamethylenediamine is obtained.

[0047] In this example, the conversion rate of adiponitrile hydrogenation is 99.6%, and the selectivity of hexamethylenediamine is 95.36%.

[0048] Example 2

[0049] A production process for catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine includes the following steps:

[0050] 1) Add 50 g of Ni(NO3)2 into 50 g of pure water to make the concentration of the Ni(NO3)2 aqueous solution reach 50%, then add 10.27 g of Cu(NO3)2 to obtain a mixed solution; then drop the mixed solution into 36.16 g of a nanoscale Al2O3 catalyst support, filter after ultrasonic adsorption for 2 h, put it into a small meshing machine for meshing, and dry it in an oven at 100 °C for 3 h to obtain a catalyst precursor;

[0051] 2) Place the catalyst precursor in an O2 / Ar mixed gas and calcine it at 600 °C for 8 h, and after grinding, obtain a catalyst;

[0052] 3) Mix 20 g of adiponitrile and 70 g of ethanol evenly to obtain an adiponitrile-ethanol solution; fill the catalyst into the top of the fluidized bed reactor, and then use a metering pump to introduce the adiponitrile-ethanol solution into the bottom of the fluidized bed reactor at a flow rate of 40 mL / h, and introduce high-pressure hydrogen into the fluidized bed reactor at a flow rate of 1 L / h. Control the liquid-phase volume space velocity of the adiponitrile-ethanol solution to be 2 h -1 , and the gas-phase volume space velocity of hydrogen to be 20 h -1 , and react adiponitrile and hydrogen with the catalyst at a temperature of 120 °C and a pressure of 7 MPa for 48 h to obtain crude hexamethylenediamine;

[0053] 4) First, perform solid-liquid separation on the effluent of the fluidized bed reactor containing crude hexamethylenediamine. The obtained solid is the catalyst that has participated in the reaction. After separation, it is calcined in an O2 / Ar mixed gas and reused; the obtained liquid is subjected to distillation separation to obtain hexamethylenediamine.

[0054] In this example, the hydrogenation conversion rate of adiponitrile is 99.7%, and the selectivity of hexamethylenediamine is 97.81%.

[0055] The structure of the fluidized bed reactor in this example is the same as that in Example 1.

[0056] Example 3

[0057] Synthesize hexamethylenediamine in the same manner as in Example 2, except that in step 1), add 45 g of Ni(NO3)2 to 40 g of pure water, then add 12 g of Cu(NO3)2 to obtain a mixed solution; then drop the mixed solution into 35 g of a nanoscale Al2O3 catalyst support, and the remaining reaction conditions are the same as those in Example 2.

[0058] In this example, the conversion rate of adiponitrile is 99.5%. The selectivity of hexamethylenediamine is 93.21%.

[0059] Example 4

[0060] Synthesize hexamethylenediamine in the same manner as in Example 2, except that in step 1), add 50 g of Mg(NO3)2 to 50 g of pure water, then add 12 g of Co(NO3)2 to obtain a mixed solution; then drop the mixed solution into 35 g of a nanoscale Al2O3 catalyst support, and the remaining reaction conditions are the same as those in Example 2.

[0061] In this example, the conversion rate of adiponitrile is 99.6%. The selectivity of hexamethylenediamine is 96.32%.

[0062] Example 5

[0063] The continuous reaction was carried out for 240 h according to the method described in Example 2, and the reaction materials were analyzed online by gas phase. The conversion rate of adiponitrile and the selectivity of hexamethylenediamine were calculated. The catalyst was separated from the bottom of the reactor and regenerated and backfilled every 48 h. Record the following Table 1 every 24 h.

[0064] Table 1

[0065] Reaction duration (h) Conversion rate of adiponitrile (%) Selectivity of hexamethylenediamine (%) 24 99.8 98.2 48 99.8 97.9 72 99.2 97.8 96 99.0 97.5 120 98.3 96.6 144 98.7 97.1 168 98.2 96.3 192 98.0 96.2 216 98.1 96.0 240 97.9 96.2

[0066] As can be seen from Table 1, after the catalyst prepared by the present invention is combined with the fluidized bed reactor, the conversion rate of adiponitrile remains above 97.5% after 240 h of reaction, and the selectivity of hexamethylenediamine remains above 96% after 240 h of reaction.

[0067] In summary, the production process of catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine provided by the present invention has simple process, high conversion rate, good product selectivity and mild reaction conditions. By using a fluidized bed reactor for the reaction, continuous operation can be realized and the product has good stability. After a long-time continuous reaction, the catalytic activity of the catalyst does not decrease significantly, indicating that the catalyst produced by this process has good stability.

[0068] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A production process for the catalytic hydrogenation of adiponitrile to synthesize hexamethylenediamine, characterized in that, It includes the following steps: 1) Add Ni(NO3)2 or Mg(NO3)2 to pure water to make the mass concentration of Ni(NO3)2 or Mg(NO3)2 in the aqueous solution reach 50 - 75%; then add transition metal oxide to obtain a mixed solution; then drop the mixed solution into an Al2O3 catalyst support, perform ultrasonic adsorption for 1 - 3 h, and after filtration and drying, obtain a catalyst precursor; Among them, the transition metal oxide is a metal oxide of Cu and / or Co, and the mass fraction of Cu and / or Co in the catalyst is 0% - 5%; 2) Place the catalyst precursor in an O2 / Ar mixed gas and calcine it at 500 - 750 °C for 5 - 10 h, and after grinding, obtain a catalyst; 3) Mix adiponitrile and ethanol evenly to obtain an adiponitrile solution; load the catalyst into the top of a fluidized bed reactor, and then introduce an adiponitrile solution with a mass concentration of 20-50 wt% into the fluidized bed reactor, introduce hydrogen, and control the liquid-phase volume space velocity of the adiponitrile solution to be 0.5-10 h -1 , and the gas-phase volume space velocity of hydrogen to be 5-100 h -1 , and react adiponitrile and hydrogen with the catalyst at a temperature of 70-140 °C and a pressure of 2-12 MPa for 24-240 h to obtain crude hexamethylenediamine; Among them, the specific structure of the fluidized bed reactor is as follows: The fluidized bed reactor includes a hexamethylenediamine reactor. A catalyst distributor is arranged at the top of the hexamethylenediamine reactor, a catalyst particle settler is arranged at the bottom, a solid-liquid separator is arranged on the side, and a feeding device is arranged in the center; The catalyst distributor and the catalyst particle settler are connected by a pipeline, so that the hexamethylenediamine reactor, the catalyst distributor and the catalyst particle settler form a closed loop; a catalyst calcination furnace is also arranged on this pipeline; The hexamethylenediamine reactor is connected to the solid-liquid separator by a pipeline, and the solid-liquid separator is also connected to a reaction material discharge pipe; the solid-liquid separator is connected to the catalyst particle settler by a pipeline; the hexamethylenediamine reactor, the solid-liquid separator and the catalyst particle settler form a closed loop; One end of the feeding device is a liquid feeding port, the other end is a gas feeding port, and the center is a fence-shaped reaction material distributor; 4) First perform solid-liquid separation on the discharge of the fluidized bed reactor containing crude hexamethylenediamine. The obtained solid is the catalyst that has participated in the reaction. After separation, it is calcined in an O2 / Ar mixed gas and reused; the obtained liquid is subjected to rectification separation to obtain hexamethylenediamine.

2. The production process for synthesizing hexamethylenediamine by catalytic hydrogenation of adiponitrile according to claim 1, characterized in that, In step 1), the mass concentration of Ni(NO3)2 or Mg(NO3)2 in the aqueous solution is 50 - 60%.

3. The production process for synthesizing hexamethylenediamine by catalytic hydrogenation of adiponitrile as claimed in claim 1, characterized in that, In step 1), the time of ultrasonic adsorption is 1 h, the drying temperature is 100 - 120 °C, and the drying time is 3 - 5 h.

4. The production process for synthesizing hexamethylenediamine by catalytic hydrogenation of adiponitrile as claimed in claim 1, characterized in that, In step 1), the Al2O3 catalyst support is a nano-level Al2O3 catalyst support, and the mass ratio of the Al2O3 catalyst support to Ni(NO3)2 or Mg(NO3)2 is (3 - 4):

5.

5. The production process for synthesizing hexamethylenediamine by catalytic hydrogenation of adiponitrile as described in claim 1, characterized in that, In step 2), the calcination temperature is 600 - 700 °C, and the calcination time is 8 - 10 h.

6. The production process for synthesizing hexamethylenediamine by catalytic hydrogenation of adiponitrile according to claim 1, characterized in that, In step (2), the volume ratio of O2 to Ar in the mixed gas is 2:3, and the space velocity of the mixed gas is 10 - 50 h -1 .

7. The production process for synthesizing hexamethylenediamine by catalytic hydrogenation of adiponitrile according to claim 1, characterized in that, In step 3), the reaction temperature is 100 - 120 °C, and the reaction pressure is 3 - 7 MPa.

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