Hydrogenation catalyst for preparing hexamethylenediamine, preparation method of hydrogenation catalyst and preparation method of hexamethylenediamine

Abstract

The invention discloses a hydrogenation catalyst for preparing hexamethylenediamine, a preparation method of the hydrogenation catalyst and a preparation method of the hexamethylenediamine. The method adopts a porous nickel hydrogenation catalyst with the following two necessary conditions to perform hydrogenation on adiponitrile or aminocapronitrile to prepare hexamethylenediamine: a, the D10 particle size of a nickel-aluminum alloy meets the formula ln (D10-5) > = 0.5 ln C + 3.9, and b, the initial activity index A of the hydrogenation catalyst meets the formula ln A > = 3.2-0.8 * C impurity 0.8. When the hydrogenation catalyst provided by the invention is used for preparing hexamethylenediamine, under the condition that the impurity content of the raw material is 0-0.5 wt%, the reaction high activity and poison resistance can be maintained, the unit consumption of the catalyst is obviously reduced, and the tolerance to the quality of the raw material is improved.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis and hydrogenation catalyst technology, specifically relating to a hydrogenation catalyst for preparing hexamethylenediamine and a method for preparing hexamethylenediamine. Background Technology

[0002] Hexamethylenediamine (HMD) is a versatile compound commonly used in the preparation of polyamides such as nylon 66 and hexamethylene diisocyanate.

[0003] Currently, the mainstream processes for preparing hexamethylenediamine are low-pressure hydrogenation and high-pressure hydrogenation. Low-pressure hydrogenation is the dominant process globally due to its milder process conditions and lower equipment investment. This process typically employs a gas-liquid-solid three-phase fluidized bed reactor, where the catalyst circulates within the reactor after liquid-solid separation. To maintain reaction stability, the catalyst needs to be regenerated and replaced periodically. If catalyst regeneration and replacement are not timely, catalyst loss can easily occur during the liquid-solid separation stage, leading to increased catalyst consumption.

[0004] The need for catalyst regeneration and replacement is primarily due to catalyst activity decay, which has multiple causes. One is reaction-related; with long-term operation of the reaction system, tar-like byproducts produced can clog catalyst pores, leading to activity decay – this is well-known. Another cause is impurities introduced from the raw materials, which reduce catalyst activity. Currently, the main raw material for producing hexamethylenediamine is adiponitrile, and there are three industrialized routes for adiponitrile: the butadiene method, the adipic acid method, and the acrylonitrile method. These three processes share the common impurity 2-aminocyanocyclopentene or 2-iminocyanocyclopentane (abbreviated as ACCP, ICCP, or CPI). This impurity is formed by the isomerization of adiponitrile at high temperatures and easily causes catalyst deactivation – this is also well-known, as evidenced by patents GB1367006 and WO2008 / 157218. However, research on the impact of specific impurities from different process routes on catalyst activity is limited. Examples include pyrimidine derivatives and imides in the adipic acid process, and cresol in the butadiene process. These impurities have a strong adsorption effect on nickel-based catalysts, which can lead to decreased catalyst activity, poisoning and deactivation, and increased catalyst consumption. Representative structures of these impurities are as follows:

[0005]

[0006] When it is impossible to reduce the impurity content in the raw materials of each process route, a general method needs to be developed to reduce the impact of impurities in the raw materials on catalyst activity and reduce catalyst consumption per unit. Summary of the Invention

[0007] This invention provides a hydrogenation catalyst for preparing hexamethylenediamine and its preparation method, as well as a method for preparing hexamethylenediamine. Addressing the issue that impurities in adiponitrile vary in different process routes in existing technologies, and their varying impacts on catalyst activity and consumption, this invention proposes a technical solution to resolve the influence of raw material impurities on catalyst activity and consumption.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0009] A hydrogenation catalyst for preparing hexamethylenediamine, satisfying the following two conditions:

[0010] a. The D10 grain size of nickel-aluminum alloys satisfies the empirical formula ln(D 10 -5)≥0.5ln C 杂质 +3.9, D 10 Units: um, C 杂质 The unit is wt%;

[0011] b. The initial activity index A of the hydrogenation catalyst satisfies the empirical formula ln A ≥ 3.2 - 0.8 * C 杂质 0.8 The initial activity index is measured in ml-H2 / s / g-cat.

[0012] In one embodiment, the D10 of the nickel-aluminum alloy refers to the highest particle size when the cumulative percentage of nickel-aluminum alloy particles is 10%. Common particle size testing equipment such as laser particle size analyzers and image particle size analyzers can be used for testing.

[0013] The C 杂质 This refers to the impurity content in adiponitrile or aminohexonitrile raw materials.

[0014] In one embodiment, the method for testing the initial activity index A of the hydrogenation catalyst refers to testing the instantaneous hydrogen absorption rate per unit mass of hydrogenation catalyst every 5-6 minutes within the first 20 minutes of the reaction, and taking the average value after 4 tests. For example, in a specific embodiment, the instantaneous hydrogen absorption rates A1, A2, A3, and A4 are measured using a hydrogen flow meter at the 1st, 6th, 11th, and 16th minutes of the reaction, respectively. The final activity index A = A1 + A2 + A3 + A4 / m cat / 4, where m cat. The mass of the hydrogenation catalyst is expressed in g. The units for A1 to A4 are ml-H2 / s, and the initial activity index A of the catalyst is expressed in ml-H2 / s / g-cat.

[0015] The preparation method of the hydrogenation catalyst of the present invention includes the following steps:

[0016] (1) The nickel-aluminum alloy was activated with a 20-30 wt% NaOH aqueous solution at an activation temperature of 70-80℃ for 1-2 hours. The aluminum content in the product was 10-20 wt%.

[0017] (2) Based on the mass of nickel-aluminum alloy in step (1), add 100-1000 mg / kg of formate and / or oxalate modifier based on the mass of nickel-aluminum alloy, activate at 90-100℃, activate for 1-2 h, and the resulting hydrogenation catalyst contains 5-10 wt% aluminum and is washed with water.

[0018] In step (1) of this invention, the mass ratio of NaOH aqueous solution to nickel-aluminum alloy is 4 to 8:1.

[0019] In step (2) of the present invention, the amount of the modifier added is 100 to 1000 mg / kg, for example, 100 mg / kg, 200 mg / kg, 300 mg / kg, 500 mg / kg, 1000 mg / kg or any combination thereof.

[0020] In step (2) of the present invention, the formate and / or oxalate includes one or more of ammonium formate, sodium formate, potassium formate, ammonium oxalate, sodium oxalate, and potassium oxalate.

[0021] As a preferred embodiment, in step (2) of the present invention, the pH of the water washing solution is between 7.0 and 7.5.

[0022] A method for preparing hexamethylenediamine by hydrogenation includes the following steps: adiponitrile or aminohexamethylenediamine raw material with an impurity content of 0-0.5 wt% is subjected to a hydrogenation reaction in the presence of the hydrogenation catalyst and auxiliaries described in this invention.

[0023] In one embodiment, the adiponitrile raw material includes one or more of the following: adiponitrile produced by adipic acid process, adiponitrile produced by butadiene process, adiponitrile produced by acrylonitrile process, and aminohexanonitrile produced by caprolactam process.

[0024] In one embodiment, the impurities include one or more of amides, imides, cyclopentanone and its polymers, pyrimidine derivatives, phenols, cyclopentonitrile, methylglutaronitrile, dicyandiethyl ether, and hydroxypropionitrile.

[0025] In one embodiment, the impurity content is a range of 10 mg / kg, 30 mg / kg, 50 mg / kg, 100 mg / kg, 500 mg / kg, 1000 mg / kg, 1500 mg / kg, 2000 mg / kg, 2500 mg / kg, 3000 mg / kg, 3500 mg / kg, 4000 mg / kg, 4500 mg / kg, 5000 mg / kg, or any two of these.

[0026] In one embodiment, the auxiliary agent is one or more of inorganic and organic bases, suitable examples including but not limited to one or more of NaOH, KOH, CsOH, tetramethylammonium hydroxide, and tetraethylammonium hydroxide, preferably one or more of NaOH, KOH, and tetramethylammonium hydroxide.

[0027] In one embodiment, the hydrogenation reaction is preferably carried out in the presence of a solvent, suitable examples of which include, but are not limited to, one or more of methanol, ethanol, n-propanol, isopropanol, N,N-dimethylformamide, and N,N-dimethylacetamide, preferably ethanol and / or n-propanol.

[0028] In one embodiment, the amount of the hydrogenation catalyst used in the hydrogenation reaction is 10 to 50% of the total mass of the liquid phase, including but not limited to 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, or any combination thereof.

[0029] In one embodiment, in the hydrogenation reaction, the amount of the auxiliary agent is 0.1% to 1% of the total mass of the liquid phase, including but not limited to 0.01wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, or any combination thereof, preferably 0.1% to 0.5wt%.

[0030] The total mass of the liquid phase mentioned in this invention refers to the total mass of the raw materials plus the optional solvent.

[0031] In one embodiment, the temperature of the hydrogenation reaction is 60–100°C, preferably 65–85°C, including but not limited to 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or any combination thereof.

[0032] In one embodiment, the pressure of the hydrogenation reaction is 1.5 to 5 MPa, preferably 2.0 to 3.5 MPa, including but not limited to a range of 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, or any combination thereof.

[0033] In one embodiment, the hydrogenation catalyst consumption is obtained by continuously applying it to 5 batches of batches in a batch reactor to obtain the total yield of hexamethylenediamine in 5 batches, and the total hexamethylenediamine processing capacity of the catalyst is calculated. The unit of consumption is g-cat. / kg-HMD.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) Particle size compensation and activity adjustment mechanism dynamically improves the anti-poisoning performance of hydrogenation catalyst to adapt to adiponitrile or aminohexanonitrile feedstock with different types and contents of impurities, and reduces the catalyst consumption. Compared with unadjusted commercial hydrogenation catalyst, the catalyst consumption can be reduced by about 80%, and the catalyst activity and consumption remain stable.

[0036] (2) Modifiers such as formate and oxalate are introduced during the catalyst activation stage. The formate, oxalate and other negative ions and their decomposition products can cover the strong active sites of the Raney nickel hydrogenation catalyst, reduce the adsorption of strong electronegative impurities such as aminopyrimidine and imide, maintain the long-term operation activity of the hydrogenation catalyst, and significantly reduce the single consumption of the hydrogenation catalyst. Detailed Implementation

[0037] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0038] Unless otherwise specified, the reagents, materials, instruments, and analytical methods used in the following examples are all conventional reagents, materials, instruments, and analytical methods in the art, and are all commercially available. The reagents involved can also be synthesized using conventional methods in the art. Specific conditions for experimental methods not shown in the following examples are all standard operating conditions.

[0039] The main sources of raw materials are shown in Table 1 below:

[0040] Table 1

[0041]

[0042]

[0043] In the following examples, the components of the reaction solution were analyzed by gas chromatography under the following conditions: Agilent DB-5 column, injection port temperature 280°C, FID detector temperature 300°C, column flow rate 1.5 ml / min, hydrogen flow rate 30 ml / min, air flow rate 400 ml / min, and temperature program as follows: hold at 50°C for 2 min, increase to 80°C at 5°C / min, then increase to 280°C at 15°C / min and hold for 10 min.

[0044] The present invention is further explained and illustrated below through more specific embodiments, but these do not constitute any limitation. To scale up the poisoning effect of raw material impurities on the catalyst and the catalyst consumption per unit volume on a small-scale basis, the catalyst dosage range in the following embodiments is 0.5–1 wt%.

[0045] Example 1

[0046] Preparation of hydrogenation catalysts

[0047] The hydrogenation catalyst in this embodiment is adapted to butadiene adiponitrile with a total impurity content of 0.05 wt%, including iminocyclopentadionitrile 0.005 wt%, 2-methylglutaronitrile 0.01 wt%, octadionitrile 0.03 wt%, and cresol 0.005 wt%.

[0048] 1 kg of nickel-aluminum alloy (FMR8000, D10 = 17.2 μm) was added to the activation vessel, along with 4 kg of 30 wt% NaOH aqueous solution. The catalyst was activated at 70°C for 2 hours in the first stage. After the first stage activation, the aluminum content of the catalyst was found to be 15 wt%. Then, 0.5 g of sodium formate was added to the vessel for the second stage modification activation at 90°C for 2 hours. The aluminum content of the catalyst was found to be 6 wt%. The catalyst was then washed with deionized water, and the pH of the washing solution was 7.11.

[0049] hydrogenation reaction

[0050] 300g of butadiene-based adiponitrile, 30g of hydrogenation catalyst, 200g of ethanol, and 0.5g of NaOH were added to a 1L reactor. The reactor was purged with nitrogen three times, heated to 68℃, and then hydrogen gas was introduced at a pressure of 3.5MPa. The instantaneous hydrogen absorption rate was measured at 1 min, 6 min, 11 min, and 16 min, with the hydrogen introduction rate as the zero point of timing. The initial activity index A was calculated as 24.1 ml-H2 / s / g-cat. (According to the empirical formula for the initial activity index, under the condition of 0.05wt% impurity content, the initial activity index should satisfy A≥22.8; therefore, the catalyst activity meets the requirements). The reaction continued until the hydrogen absorption rate reached 0. The mother liquor was analyzed by gas chromatography, and the hexamethylenediamine yield was calculated to be 95.5%.

[0051] After the reaction was completed, the mother liquor was filtered, and the above steps were repeated for a second batch. The yield of hexamethylenediamine was analyzed. A total of 5 batches were reused, and the amount of hexamethylenediamine processed from the 5 reused batches was calculated to obtain the catalyst consumption. The reuse results and specific data on catalyst consumption are shown in Table 1.

[0052] Example 2

[0053] Preparation of hydrogenation catalysts

[0054] The hydrogenation catalyst in this embodiment is adapted to adiponitrile produced by the adipic acid method with an impurity content of 0.3 wt%, including 0.01 wt% iminocyanocyclopentane, 0.01 wt% caprolactam, and 0.28 wt% pyrimidine derivatives.

[0055] 1 kg of nickel-aluminum alloy (Taizhou Tongling Metal, grade RTL-302, D10 = 34.3 μm) was added to the activation vessel, along with 4 kg of 20 wt% NaOH aqueous solution. The catalyst was activated at 80 °C for 1 hour in the first stage. After the first stage activation, the aluminum content of the catalyst was tested to be 20 wt%. After the first stage activation, 0.8 g of sodium oxalate was added to the vessel for the second stage modification activation at 100 °C for 2 hours. The aluminum content of the catalyst was tested to be 5 wt%. The catalyst was then washed with deionized water, and the pH of the washing solution was 7.03.

[0056] hydrogenation reaction

[0057] 300g of adipic acid-based adiponitrile, 90g of hydrogenation catalyst, 250g of ethanol, and 1.65g of NaOH were added to a 1L reactor. The reactor was purged with nitrogen three times. After heating to 85℃, hydrogen gas was introduced at a pressure of 3.1MPa. The instantaneous hydrogen absorption rate was measured at 0 min, 5 min, 10 min, and 15 min, using the hydrogen introduction as the zero point of timing. The initial activity index A was calculated as 19.8 ml-H2 / s / g-cat. (According to the empirical formula for the initial activity index, under the condition of 0.3wt% impurity content, the initial activity index should satisfy A≥18.1; therefore, the catalyst activity meets the requirements). The reaction continued until the hydrogen absorption rate reached 0. The mother liquor was analyzed by gas chromatography, and the hexamethylenediamine yield was calculated to be 98.7%.

[0058] After the reaction was completed, the mother liquor was filtered, and the above steps were repeated for a second batch. The yield of hexamethylenediamine was analyzed. A total of 5 batches were reused, and the amount of hexamethylenediamine processed from the 5 reused batches was calculated to obtain the catalyst consumption. The reuse results and specific data on catalyst consumption are shown in Table 1.

[0059] Example 3

[0060] Preparation of hydrogenation catalysts

[0061] The hydrogenation catalyst in this embodiment is adapted to adiponitrile produced by the adipic acid method with an impurity content of 0.5 wt%, including 0.02 wt% iminocyanocyclopentane, 0.01 wt% caprolactam, and 0.47 wt% pyrimidine derivatives.

[0062] 1 kg of nickel-aluminum alloy (manufactured by Taizhou Tongling Metal, grade RTL-401, D10 = 42.5 μm) was added to the activation vessel, along with 4 kg of 26 wt% NaOH aqueous solution. The catalyst was activated at 75 °C for 1.5 h in the first stage. After the first stage activation, the aluminum content of the catalyst was tested to be 15 wt%. After the first stage activation, 1 g of ammonium oxalate was added to the vessel for the second stage modification activation at 93 °C for 2 h. The aluminum content of the catalyst was tested to be 8 wt%. The catalyst was then washed with deionized water, and the pH of the washing solution was 7.07.

[0063] hydrogenation reaction

[0064] 320g of adipic acid-based adiponitrile, 160g of hydrogenation catalyst, 200g of ethanol, and 2.6g of NaOH were added to a 1L reactor. The reactor was purged with nitrogen three times. After heating to 74℃, hydrogen gas was introduced at a pressure of 2.5MPa. The instantaneous hydrogen absorption rate was measured at 0 min, 5 min, 10 min, and 5 min, using the hydrogen introduction as the zero point of timing. The initial activity index A was calculated as 16.7 ml-H2 / s / g-cat. (According to the empirical formula for the initial activity index, under the condition of 0.5wt% impurity content, the initial activity index should satisfy A≥15.5; therefore, the catalyst activity meets the requirements). The reaction continued until the hydrogen absorption rate reached 0. The mother liquor was analyzed by gas chromatography, and the hexamethylenediamine yield was calculated to be 98.1%.

[0065] After the reaction was completed, the mother liquor was filtered, and the above steps were repeated for a second batch. The yield of hexamethylenediamine was analyzed. A total of 5 batches were reused, and the amount of hexamethylenediamine processed from the 5 reused batches was calculated to obtain the catalyst consumption. The reuse results and specific data on catalyst consumption are shown in Table 1.

[0066] Example 4

[0067] Preparation of hydrogenation catalysts

[0068] The hydrogenation catalyst in this embodiment is adapted to acrylonitrile adiponitrile with an impurity content of 0.2 wt%, wherein the impurity composition is 0.06 wt% succinate, 0.1 wt% 2-cyanoethyl ether, 0.01 wt% iminocyanocyclopentane, 0.02 wt% 2-methylglutaronitrile, and 0.01 wt% hydroxypropionitrile.

[0069] 1 kg of nickel-aluminum alloy (manufactured by Jiangsu Reni Technology, D10 = 28.4 μm) was added to the activation vessel, along with 4 kg of 32 wt% NaOH aqueous solution. The catalyst was activated at 72°C for 2 hours in the first stage, resulting in an aluminum content of 13 wt%. 0.1 g of ammonium formate was then added to the vessel for a second stage of modification and activation at 97°C for 1.2 hours. The catalyst aluminum content was tested to be 6 wt%, and the catalyst was washed with deionized water. The pH of the washing solution was 7.13.

[0070] hydrogenation reaction

[0071] 350g of acrylonitrile-based adiponitrile and 88.5g of hydrogenation catalyst were added to a 1L reactor, along with 240g of ethanol and 1.3g of NaOH. The reactor was purged with nitrogen three times. After heating to 65℃, hydrogen gas was introduced at a pressure of 2.8MPa. The instantaneous hydrogen absorption rate was measured at 2 min, 7 min, 12 min, and 17 min, using the hydrogen introduction as the zero point of timing. The initial activity index A was calculated as 20.2 ml-H2 / s / g-cat. (According to the empirical formula for the initial activity index, under the condition of 0.2wt% impurity content, the activity index should satisfy A≥19.7; therefore, the catalyst activity meets the requirements). The reaction continued until the hydrogen absorption rate reached 0. The mother liquor was analyzed by gas chromatography, and the hexamethylenediamine yield was calculated to be 95.0%.

[0072] After the reaction was completed, the mother liquor was filtered, and the above steps were repeated for a second batch. The yield of hexamethylenediamine was analyzed. A total of 5 batches were reused, and the amount of hexamethylenediamine processed from the 5 reused batches was calculated to obtain the catalyst consumption. The reuse results and specific data on catalyst consumption are shown in Table 1.

[0073] Example 5

[0074] Preparation of hydrogenation catalysts

[0075] The hydrogenation catalyst in this embodiment is adapted to an aminohexanonitrile with an impurity content of 0.1 wt%, including 0.04 wt% 6-aminohexanoamide and 0.06 wt% aminohexanonitrile dimer.

[0076] 1 kg of nickel-aluminum alloy (manufacturer: Shandong Jiahong, grade JH-18, D10 = 22.3 μm) was added to the activation vessel, along with 4 kg of 30 wt% NaOH aqueous solution. The first-stage activation was carried out at 78 °C for 2 h. After the first-stage activation, the actual aluminum content of the catalyst was 10 wt%. 0.3 g of potassium oxalate was added to the vessel for the second-stage modification activation at 96 °C for 2 h. The aluminum content of the catalyst was controlled at 8 wt%. The catalyst was then washed with deionized water, and the pH of the washing solution was 7.15.

[0077] hydrogenation reaction

[0078] 350g of aminohexanonitrile, 65g of hydrogenation catalyst, 300g of ethanol, and 2.6g of NaOH were added to a 1L reactor. The reactor was purged with nitrogen three times. After heating to 79℃, hydrogen gas was introduced at a pressure of 2.7MPa. The instantaneous hydrogen absorption rate was measured at 0 min, 5 min, 10 min, and 15 min, with the hydrogen introduction rate as the zero point of timing. The initial activity index A was calculated as 23.5 ml-H2 / s / g-cat. (According to the empirical formula for the initial activity index, under the condition of 0.2wt% impurity content, the initial activity index should satisfy A≥21.6; therefore, the catalyst activity meets the requirements). The reaction continued until the hydrogen absorption rate reached 0. The mother liquor was analyzed by gas chromatography, and the yield of hexamethylenediamine was calculated to be 95.8%.

[0079] After the reaction was completed, the mother liquor was filtered, and the above steps were repeated for a second batch. The yield of hexamethylenediamine was analyzed. A total of 5 batches were reused, and the amount of hexamethylenediamine processed from the 5 reused batches was calculated to obtain the catalyst consumption. The reuse results and specific data on catalyst consumption are shown in Table 1.

[0080] Comparative Example 1

[0081] The method described in Example 3 differs from that of Example 3 in that the catalyst D10 = 8.9 μm. Specifically, 1 kg of nickel-aluminum alloy (Taizhou Tongling Metal, grade RTL-401, D10 = 8.9 μm) was added to the activation vessel, along with 4 kg of 26 wt% NaOH aqueous solution. The catalyst was activated at 75°C for 1.5 h in the first stage. After the first stage activation, the catalyst aluminum content was tested to be 15 wt%. After the first stage activation, 1 g of ammonium oxalate was added to the vessel for a second stage of modification activation at 93°C for 2 h. The catalyst aluminum content was then tested to be 8 wt%. The catalyst was washed with deionized water (pH = 7.07). This catalyst has a lower D10 requirement than the empirical formula, with an initial activity index of 22 ml-H2 / s / g-cat. Compared to Example 3, the catalyst's resistance to poisoning is reduced, and small-particle-size catalyst is gradually lost during reuse. Therefore, the reuse activity is lower than that of Example 3. The reuse yield and catalyst consumption comparison are shown in Table 2.

[0082] Comparative Example 2

[0083] Referring to the method in Example 3, the difference lies in the initial catalyst activity index of 11.8 ml-H2 / s / g-cat. The specific preparation method involves adding 1 kg of nickel-aluminum alloy (manufactured by Taizhou Tongling Metal, grade RTL-401, D10 = 42.5 μm) to the activation vessel, followed by 4 kg of 26 wt% NaOH aqueous solution. The catalyst is activated at 75°C for 1 hour in the first stage. After the first stage activation, the catalyst aluminum content is tested to be 20 wt%. After the first stage activation, 1 g of ammonium oxalate is added to the vessel for a second stage modification activation at 93°C for 1 hour. The catalyst aluminum content is then tested to be 12 wt%. The catalyst is washed with deionized water (pH = 7.07). Compared to Example 3, the initial catalyst activity is reduced. The yield and catalyst consumption are compared in Table 2.

[0084] Comparative Example 3

[0085] The method is the same as in Example 3, except that the nickel-aluminum alloy is not modified and activated with ammonium oxalate. Compared with Example 3, the catalyst's resistance to poisoning is reduced. The comparison of yield and catalyst consumption is shown in Table 2.

[0086] Table 2 Comparison of catalyst utilization rate and catalyst consumption per unit area

[0087]

[0088] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A hydrogenation catalyst for preparing hexanediamine, satisfying the following two conditions: a. The D10 particle size of the nickel-aluminum alloy satisfies the empirical formula ln(D 10 -5) ≥ 0.5 ln C 杂质 + 3.9, D 10 in units of um, C 杂质 in units of wt%; b. the initial activity index A of the hydrogenation catalyst satisfies the empirical formula ln A > 3.2 - 0.8 * C 杂质 0.8 A is in ml-H2 / s / g-cat.

2. The hydrogenation catalyst according to claim 1, characterized by D10 of the nickel-aluminum alloy refers to the highest particle size at which the cumulative percentage of nickel-aluminum alloy particles is 10%.

3. The hydrogenation catalyst according to claim 1 or 2, characterized in that, The C 杂质 , refers to the impurity content in the adiponitrile or aminocapronitrile feedstock.

4. The hydrogenation catalyst according to any one of claims 1 to 3, characterized in that, The test method for the initial activity index A of the hydrogenation catalyst is that the instantaneous hydrogen absorption rate per unit mass of the hydrogenation catalyst is tested every 5-6 min within 20 min before the reaction, and the average value of 4 tests is taken.

5. A method for preparing the hydrogenation catalyst according to any one of claims 1-4, comprising the following steps: (1) activating the nickel-aluminum alloy with 20-30 wt% NaOH aqueous solution, the activation temperature is 70-80℃, the activation time is 1-2 h, and the aluminum content in the obtained product is 10-20 wt%; (2) adding 100-1000 mg / kg of formate and / or oxalate modifier based on the mass of the nickel-aluminum alloy, the activation temperature is 90-100℃, the activation time is 1-2 h, the aluminum content in the obtained hydrogenation catalyst is 5-10 wt%, and the product is washed with water.

6. The method of claim 5, wherein, The mass ratio of NaOH aqueous solution to nickel-aluminum alloy is 4-8:1; and / or, the addition amount of the modifier is 100-1000 mg / kg, preferably, the formate and / or oxalate include one or more of ammonium formate, sodium formate, potassium formate, ammonium oxalate, sodium oxalate, and potassium oxalate.

7. A process for the preparation of hexamethylenediamine comprising the steps of: Hexanedinitrile or aminohexanitrile with an impurity content of 0-0.5 wt% is used as the raw material, and a hydrogenation reaction is carried out in the presence of the hydrogenation catalyst according to any one of claims 1-4 or the hydrogenation catalyst prepared by the method according to any one of claims 5-6 and an auxiliary agent.

8. The method of claim 7, wherein, The raw material includes one or more of adipic acid method hexanedinitrile, butadiene method hexanedinitrile, acrylonitrile method hexanedinitrile, and caprolactam method aminohexanitrile; and the impurities include one or more of amide, imide, cyclopentanone and its polymers, pyrimidine derivatives, phenols, cyclopentanitrile, methyl glutaronitrile, dicyanethanol ether, and hydroxypropionitrile.

9. The method according to claim 7 or 8, characterized in that, The auxiliary agent is one or more of inorganic bases and organic bases, and preferably one or more of NaOH, KOH, CsOH, tetramethylammonium hydroxide, and tetraethylammonium hydroxide.

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