Preparation method and application of high-performance hexamethylenediamine synthesis catalyst

Abstract

The invention discloses a preparation method and application of a high-performance hexamethylenediamine synthesis catalyst, and belongs to the technical field of new materials. A nickel-based hexabasic alloy is prepared from 10%-30% of Ni, 20%-30% of Fe, 0.5%-3% of Mo, 0.5%-3% of Cr, 0.5%-3% of Mn and 50%-60% of Al through a vacuum melting method, the nickel-based hexabasic alloy is physically crushed into alloy powder, then the porous nickel-based catalyst is prepared through a dealloying method, iron plays a role in reducing the cost, the selectivity is improved through the microelement molybdenum, the mechanical strength is improved through the chromium, and the catalytic activity is improved through the manganese. The catalyst has the characteristics of simple preparation process, low preparation cost and the like, has more excellent reaction activity, target selectivity and stability in the reaction of synthesizing hexamethylenediamine through hydrogenation of adiponitrile compared with an industrial catalyst, and shows good economic benefits and application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of porous materials, and particularly relates to a preparation method of a high-performance porous nickel-based catalyst and application thereof in hydrogenating adiponitrile to synthesize hexamethylenediamine. Background Art

[0002] Hexamethylenediamine is an important chemical raw material, primarily used in the production of key chemicals such as nylon 66, nylon 610, epoxy resin, and HDI (1,6-hexamethylenediisocyanate). Production methods include adiponitrile hydrogenation, the butadiene process, hexamethylenediol amination, caprolactam vapor-phase amination and hydrogenation, and adipic acid amination. Adiponitrile hydrogenation is widely used due to its low investment and simple process.

[0003] Adiponitrile hydrogenation methods are divided into high-pressure and low-pressure hydrogenation methods. High-pressure hydrogenation primarily uses iron-based catalysts, while low-pressure hydrogenation primarily uses supported nickel or Raney catalysts. The low-pressure method is safer and is adopted by most manufacturers both domestically and internationally. Compared to supported nickel catalysts, Raney catalysts are more active, with Raney nickel being the primary industrial catalyst. However, the selectivity of Raney nickel catalysts for the target product, hexamethylenediamine, needs to be further improved. Byproducts such as 1,2-cyclohexanediamine (DCH), which has a similar boiling point to hexamethylenediamine, complicate separation. Furthermore, Raney nickel catalysts are prone to breakage during use and have poor stability, resulting in limited recycling and increased costs. Furthermore, Raney nickel catalysts are subject to fluctuations in nickel prices, resulting in relatively high raw material costs. Therefore, the development of a new, low-cost, high-performance, highly selective, and highly stable catalyst for the hydrogenation of adiponitrile to hexamethylenediamine is crucial.

[0004] Patents CN115335356A and US2003 / 0144552A disclose methods for hydrogenating adiponitrile using Raney nickel as a catalyst and KOH and a basic compound as co-catalysts. While the addition of a base can improve the selectivity of hexamethylenediamine, the results remain limited, and the catalytic performance and stability remain largely unresolved. Patent CN103977819A discloses a method for modifying a Raney nickel catalyst used in the hydrogenation of adiponitrile to produce hexamethylenediamine. However, this method requires post-treatment of the Raney nickel catalyst, resulting in a cumbersome preparation process and increased costs. Furthermore, the catalyst's stability remains unknown. Summary of the Invention

[0005] The present invention aims to provide a method for preparing a high-performance hexamethylenediamine synthesis catalyst, thereby solving the problems of low selectivity and poor stability of traditional Raney nickel catalysts. At the same time, it provides a new idea for the preparation of low-cost porous nickel-based catalysts, which has important technical value and practical application prospects.

[0006] The technical solution adopted in the present invention is:

[0007] The method for preparing the high-performance porous nickel-based catalyst of the present invention comprises the following steps:

[0008] First, a nickel-based hexametallic alloy precursor is prepared by vacuum melting Ni, Fe, Cr, Mo, Mn, and Al in a ratio of Ni 10-30%, Fe 20-30%, Mo 0.5-3%, Cr 0.5-3%, Mn 0.5-3%, and Al 50-60%. The precursor is then physically crushed into alloy powder, and then an alkali dealloying method is used to prepare a porous nickel-based catalyst. After alkali dealloying, the contents of the main components Ni and Fe in the porous nickel-based catalyst obtained are: Ni 20-50%, Fe 35-65%, and the total content of Mo, Cr, Mn, and Al among other elements is 10-15%.

[0009] The catalyst is used in the hydrogenation of adiponitrile to synthesize hexamethylenediamine, and exhibits high selectivity, activity and stability.

[0010] Wherein, the particle size of the alloy powder is 200-800 mesh.

[0011] In the dealloying process, the alkali used is at least one of NaOH and KOH, the concentration of the alkali is 10-30%, the treatment temperature is 25-80° C., and the treatment time is 0.5-4 h.

[0012] The pore volume of the porous nickel-based catalyst is 0.1-0.2 cm 3 / g, with a specific surface area of ​​70-110m 2 / g.

[0013] The obtained catalyst is used in the reaction of hydrogenating adiponitrile to synthesize hexamethylenediamine. Under the condition of complete conversion of adiponitrile, the selectivity of hexamethylenediamine exceeds 99%, and the activity retention rate exceeds 80% after repeated application.

[0014] Among them, in the reaction of hydrogenating adiponitrile to synthesize hexamethylenediamine, the reaction conditions are: 33% adiponitrile, 60% ethanol, 6% water, 0.25% sodium hydroxide, 1% catalyst, reaction temperature 73°C, reaction pressure 2.2 MPa, and reaction time 1-2 hours.

[0015] In the present invention, the obtained catalyst can achieve high activity, high selectivity and high stability, thanks to the synergistic effect between the metals. Among them, Ni and Mn are the main active sites, Mo can promote the adsorption and dissociation of hydrogen and improve the selectivity of the target product hexamethylenediamine, Cr and Mn play a role in increasing the mechanical properties of the catalyst, Fe can mainly dilute the Ni content, further reducing the cost of the catalyst, and the ratio between each element plays a crucial role in the comprehensive performance of the catalyst.

[0016] The technical effects of the present invention are: compared with supported nickel catalysts and Raney nickel catalysts, it has higher activity in the hexamethylenediamine synthesis reaction, further improves the selectivity of hexamethylenediamine, and improves the stability issues of traditional Raney nickel applications. In addition, compared with supported nickel catalysts and post-modified Raney nickel catalysts, the method of the present invention is simple to process, easy to scale up industrial production, and has lower raw material and preparation costs, showing broad application potential in the field of industrial catalysis. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is described in detail below with reference to specific embodiments.

[0018] Example 1

[0019] Using various pure metals as raw materials, a hexavalent nickel-iron-chromium-molybdenum-manganese-aluminum alloy was melted in a vacuum smelting process at a temperature of 1400°C and then cast. The alloy powder was then physically crushed, using methods such as jaw crushing, disc grinding, Raymond milling, and air flow crushing, to obtain a 200-800 mesh alloy powder. Alkaline dealloying was then used to remove most of the aluminum, forming a porous nickel-based catalyst. The dealloying conditions were 30% sodium hydroxide at 60°C for 2 hours. This catalyst was then used in the hydrogenation of adiponitrile to hexamethylenediamine. The reaction conditions were: 33% adiponitrile, 60% ethanol, 6% water, 0.25% sodium hydroxide, 1% catalyst, reaction temperature 73°C, reaction pressure 2.2 MPa, and reaction time 1 hour. By adjusting the ratios of the elements in the original alloy, the physical properties and performance of the final catalyst could be manipulated, as shown in Table 1. For comparison, industrially used Raney nickel achieved complete conversion under the same reaction conditions, but the selectivity was only 41%.

[0020] Table 1 Catalyst physical properties and performance

[0021]

[0022] Example 2

[0023] Using various pure metals as raw materials, vacuum melting method is used to melt nickel-iron-chromium-molybdenum-manganese-aluminum hexametallic alloy, the composition of which is Ni 24 Fe 24 Cr1Mo 2.5 Mn1Al 47.5The nickel-based catalyst was melted at 1400°C and cast. Physical crushing, such as by jaw crushing, disc grinding, Raymond milling, or air flow crushing, yielded a 200-800 mesh alloy powder. Alkaline dealloying was then used to remove most of the aluminum, forming a porous nickel-based catalyst. The dealloying conditions were 30% sodium hydroxide at 60°C for 2 hours. This catalyst was then used in the hydrogenation of adiponitrile to hexamethylenediamine. The reaction conditions were: 33% adiponitrile, 60% ethanol, 6% water, 0.25% sodium hydroxide, 1% catalyst, 73°C, 2.2 MPa, and 1 hour. By adjusting the dealloying process, the physical properties and performance of the final catalyst can be manipulated, as shown in Table 2.

[0024] Table 2 Catalyst physical properties and performance

[0025]

[0026] Example 3

[0027] Using various pure metals as raw materials, vacuum melting method is used to melt nickel-iron-chromium-molybdenum-manganese-aluminum hexametallic alloy, the composition of which is Ni 24 Fe 24 Cr1Mo 2.5 Mn1Al 47.5 The product was smelted at 1400°C and cast. It was then physically crushed, using methods such as jaw crushing, disc grinding, Raymond milling, and air flow crushing, to produce a 200-800 mesh alloy powder. Alkaline dealloying was then used to remove most of the aluminum, forming a porous nickel-based catalyst. This catalyst was then used in the hydrogenation of adiponitrile to hexamethylenediamine. The reaction conditions were: 33% adiponitrile, 60% ethanol, 6% water, 0.25% sodium hydroxide, 1% catalyst, reaction temperature 73°C, reaction pressure 2.2 MPa, and reaction time 2 h. Table 3 compares the performance of the catalyst with that of an industrial Raney nickel catalyst. Compared to the industrial catalyst, the porous nickel-based catalyst exhibited higher reaction rates and final product selectivity.

[0028] Table 3 Comparison of catalyst performance

[0029] catalyst Adiponitrile conversion rate (%) Hexamethylenediamine selectivity (%) <![CDATA[Ni 44 Fe 44 Cr 0.4 My 0.8 Mr. 0.4 Al 10 ]]> 100 99.2 Industrial Raney Nickel 100 95.6

[0030] Example 4

[0031] Using various pure metals as raw materials, vacuum melting method is used to melt nickel-iron-chromium-molybdenum-manganese-aluminum hexametallic alloy, the composition of which is Ni 24 Fe 24 Cr1Mo 2.5 Mn1Al 47.5The catalyst was melted at 1400°C and cast into a mold. It was then physically crushed, using methods such as jaw crushing, disc grinding, Raymond milling, and air flow crushing, to obtain a 200-800 mesh alloy powder. Alkaline dealloying was then used to remove most of the aluminum, forming a porous nickel-based catalyst. This catalyst was then used in the hydrogenation of adiponitrile to hexamethylenediamine. The reaction conditions were: 33% adiponitrile, 60% ethanol, 6% water, 0.25% sodium hydroxide, 1% catalyst, 73°C, 2.2 MPa, and 2 hours. The catalyst was then tested for multiple cycles under the same conditions, with only the reaction liquid being drawn and replenished, eliminating the need for catalyst pretreatment. This is shown in Table 4. Compared to industrial catalysts, the porous nickel-based catalyst exhibited greater stability, retaining over 80% activity after five cycles.

[0032] Table 4 Cyclic stability of catalysts

[0033] Porous nickel application times Adiponitrile conversion rate (%) Hexamethylenediamine selectivity (%) Activity retention rate (%) 1 100 99.2 - 2 100 93.5 94.3 3 100 89.2 90.0 4 97.2 84.6 83.0 5 96.3 83.3 80.9 Industrial Raney Nickel Application Times Adiponitrile conversion rate (%) Hexamethylenediamine selectivity (%) Activity retention rate (%) 1 100 95.6 - 2 96.3 88.2 88.8 3 82.1 72.9 62.6

[0034] In the present invention, the composition of the nickel-iron-chromium-molybdenum-manganese-aluminum hexametallic alloy is not limited to the Ni 24 Fe 24 Cr1Mo 2.5 Mn1Al 47.5 The specific composition ratio can be selected from Ni 10-30%, Fe 20-30%, Mo 0.5-3%, Cr0.5-3%, Mn 0.5-3%, and Al 50-60%.

[0035] In the present invention, a porous nickel-based catalyst is formed by removing most of the aluminum through an alkali dealloying method. The dealloying conditions are not limited to those in the above embodiment. The alkali used can be at least one of NaOH or KOH. Specific conditions can be selected within the following ranges: alkali concentration of 10-30%, treatment temperature of 25-80°C, and treatment time of 0.5-4 hours. The porous nickel-based catalyst obtained after alkali dealloying has Ni and Fe contents of 20-50% Ni and 30-65% Fe, and the total content of other elements, Mo, Cr, Mn, and Al, is 10-15%.

[0036] Based on the above embodiments, the present invention achieves the preparation of a new porous nickel-based catalyst by optimizing the metal elements and their amounts, vacuum melting and dealloying, and optimizing process conditions, resulting in a high-performance hexamethylenediamine synthesis catalyst. Compared to industrial catalysts, this catalyst exhibits superior reactivity, target selectivity, and stability in the hydrogenation of adiponitrile to hexamethylenediamine, demonstrating outstanding technical effects, good economic benefits, and promising application prospects.

[0037] It should be further noted that the examples of the above embodiments of the present invention do not cover all combinations of process conditions specified in the technical solution of the present invention. These examples are intended only to facilitate understanding of the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any obvious adjustments and modifications made to the technical solution of the present invention that fall within the technical concept of the present invention are also intended to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance hexamethylenediamine synthesis catalyst, characterized in that The method comprises the following steps: vacuum melting Ni, Fe, Cr, Mo, Mn and Al in proportion to prepare a hexavalent nickel-based alloy; physically crushing the alloy into alloy powder; and adopting an alkali dealloying method to prepare a porous nickel-based catalyst. The hexavalent nickel-based alloy is NiFeCrMoMnAl, and its specific composition ratio is: Ni 10-30%, Fe 20-30%, Mo 0.5-3%, Cr 0.5-3%, Mn 0.5-3% and Al 50-60%.

2. The method according to claim 1, wherein: The contents of Ni and Fe in the porous nickel-based catalyst obtained after alkali dealloying are: Ni 20-50%, Fe 35-65%, and the total content of other elements Mo, Cr, Mn and Al is 10-15%.

3. The method according to claim 1, wherein: The vacuum melting temperature is 1400℃.

4. The method according to claim 1, wherein: The particle size of the alloy powder after physical crushing is 200-800 mesh.

5. The method according to claim 1, wherein: The alkali dealloying method comprises the following steps: using at least one of NaOH and KOH as the alkali, with the alkali concentration being 10-30%, the treatment temperature being 25-80° C., and the treatment time being 0.5-4 hours.

6. The method according to claim 1, wherein: The pore volume of the porous nickel-based catalyst after dealloying treatment is 0.1-0.2 cm 3 / g, with a specific surface area of ​​70-110m 2 / g.

7. Use of the porous nickel-based catalyst obtained by the method according to any one of claims 1 to 6, characterized in that When applied to the reaction of hydrogenating adiponitrile to synthesize hexamethylenediamine, under the condition of complete conversion of adiponitrile, the selectivity of hexamethylenediamine exceeds 99%, and the activity retention rate exceeds 80% after repeated application.

8. The use according to claim 7, characterized in that: In the reaction of hydrogenating adiponitrile to synthesize hexamethylenediamine, the reaction conditions are: 33% adiponitrile, 60% ethanol, 6% water, 0.25% sodium hydroxide, 1% catalyst, reaction temperature 73°C, reaction pressure 2.2 MPa, and reaction time 1-2 hours.

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