A co-based catalyst for hydrogenation of nitrile and a preparation method and application thereof

Abstract

The application discloses a nitrile hydrogenation Co-based catalyst and a preparation method and application thereof. The preparation method comprises the following steps: dissolving soluble salts of Al and Mg, a template agent and a dispersing agent in water, and adding ammonia water after stirring; performing hydrothermal reaction on the solution, and obtaining a mesoporous Al2O3-Mg carrier after filtration, washing and drying; performing ball milling and calcination on the mesoporous Al2O3-Mg carrier and nitrate salts of Co, Mo and a metal additive M, and obtaining a catalyst precursor; kneading the catalyst precursor with pseudo-boehmite, a nitric acid solution and a extrusion aid, and then performing extrusion molding, drying and calcination to obtain a Co-Mo-M / Al2O3-Mg catalyst. The mesoporous carrier containing the template agent is used in combination with the ball milling mode, the active components are fully dispersed, the hydrogenation activity of the catalyst is effectively improved, the side reaction is effectively inhibited under the action of carrier alkali modification and the metal additive, the product selectivity is improved, and the addition of alkaline substances in the reaction system is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a Co-based catalyst for nitrile hydrogenation and a preparation method and application thereof. BACKGROUND

[0002] Primary and secondary amine compounds are important precursors and intermediates in the chemical, pharmaceutical, agrochemical, polymer, dye and material industries, especially as epoxy resin curing agents, with a market size of 41 billion US dollars in 2021. Primary and secondary amine compounds are mainly produced by nitrile hydrogenation process. The current industrial nitrile hydrogenation catalysts are mainly Raney nickel and copper chromite, which require harsh reaction conditions and are toxic. At the same time, the nitrile hydrogenation process is mostly limited to tank reactors, with small production scale and low degree of continuity.

[0003] Co-based catalysts are widely used. Literature ACS Catal., 2017, 7, 275-84. reports a highly efficient metal-organic framework (MOF) derived bifunctional N-doped Co / C catalyst system for the selective transfer hydrogenation of nitriles to primary amines under base-free conditions. In the presence of isopropanol as a proton donor solvent, the optimized catalyst system can convert different nitriles into primary amines with high selectivity (>95%). Literature J. Am. Chem. Soc. 138 (2016) 8809-14. describes a Co-based supported catalyst prepared by pyrolysis, with α-Al2O3 as the support. This system can effectively reduce aliphatic nitriles and dinitriles to primary amines. In the presence of isopropanol and ammonia at 5 bar, 85℃, heptane nitrile is hydrogenated to heptane amine with a yield of 98%. Literature Green Chem. 2019, 21, 2448-61. proposes a graphene-coated Co3O4-Co / C (Co: 4.5wt%) catalyst, which has good primary amine yield (75-95%) in the presence of NH3 at 120℃ and 25 bar. However, the coating method sacrifices some intrinsic activity of the catalyst and reduces the TOF value. Patent CN111196763B reports a catalyst with active component M-Re (M is Ni, Co or Cu) applied to 3-aminopropyl cyanide hydrogenation, which has high activity, but Ru is introduced when the additive is doped, which increases the cost. Patent CN112934225B reports a Ni-Co catalyst prepared by coprecipitation, which is used for the production of m-xylylenediamine by fixed-bed continuous hydrogenation, with a product selectivity of more than 98%. However, 86wt% liquid ammonia is used as the reaction solvent, and the reaction pressure is relatively high, exceeding 8MPa, and the reaction conditions are relatively harsh.

[0004] From the above disclosed documents and patents, it can be seen that the Co-based catalyst has good catalytic activity in the selective hydrogenation reaction of nitriles, but the catalyst preparation process is complex. At the same time, in the process of selective hydrogenation of nitrile compounds, in order to reduce the occurrence of side reactions, inorganic alkali additives need to be added to the reaction system, which brings inconvenience to the subsequent product refining and produces difficult-to-handle solid waste. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a Co-based catalyst for nitrile hydrogenation and a preparation method and application thereof. The catalyst does not need to add inorganic alkaline additives in the process of nitrile hydrogenation reaction, the subsequent product purification process is simple, and no solid waste is produced. And the preparation method is simple, which can be applied to fixed bed reactor to realize the continuous nitrile hydrogenation.

[0006] In the first aspect, the present application provides a preparation method of a Co-based catalyst for nitrile hydrogenation, which is realized by using the following technical scheme.

[0007] The preparation method of the Co-based catalyst for nitrile hydrogenation comprises the following steps:

[0008] S1. Dissolve the soluble salts of Al and Mg, a template agent and a dispersing agent in water, and then add ammonia water after stirring;

[0009] S2. The obtained solution is subjected to hydrothermal reaction, and after filtration, washing and drying, a mesoporous Al2O3-Mg carrier containing a template agent is obtained;

[0010] S3. After ball milling and calcination of the mesoporous Al2O3-Mg carrier and nitrate salts of Co, Mo and M, a catalyst precursor is obtained; wherein M is a metal additive;

[0011] S4. The catalyst precursor is kneaded with pseudoboehmite, concentrated nitric acid and a extrusion aid, then extruded into a shape, and then dried and calcined to obtain a Co-Mo-M / Al2O3-Mg catalyst.

[0012] By using the above technical scheme, the present application prepares a mesoporous Al2O3-Mg carrier modified by Mg by a hydrothermal method, and then loads active components by a ball milling method to obtain a Co-Mo-M / Al2O3-Mg catalyst. Among them, the high specific surface area of the mesoporous carrier is beneficial to the dispersion of the metal active site, the addition of the alkali metal Mg helps to change the acid-base property of the carrier and reduce the adsorption capacity of amine substances on the catalyst surface, thereby preparing a nitrile hydrogenation catalyst for primary amine or secondary amine with high dispersion and good reaction selectivity.

[0013] Furthermore, the content range of the metal elements is as follows: the content of Co is 20-50 wt%; the content of Mo is 5-10 wt%; the metal additives are selected from one or more of Ca, K, Na, Ce, Li, and Mn, with a content of 0-5 wt%; Al2O3-Mg is a Mg-doped mesoporous alumina carrier with a content of 45-75 wt%, of which the Mg content is 1-5 wt%.

[0014] Furthermore, in step S1, the soluble salts of Al and Mg are selected from one or more of nitrates, sulfates, and chlorides.

[0015] Furthermore, in step S1, the dispersant is selected from one or more of PEG-600, PEG-800, PEG-1000, and PEG-10000, with an amount of 5-25 wt%; the template agent is selected from F127 (Pluronic F127), with an amount of 5-20 wt%.

[0016] Furthermore, in step S1, the stirring time is 4-8 hours; ammonia water is added until the pH is 7-10.

[0017] Furthermore, in step S2, the hydrothermal reaction temperature is 80-120℃, the time is 12-24h, and the drying temperature is 80-120℃.

[0018] Furthermore, in step S3, the ball milling time is 6-12 hours, the ball-to-material ratio is (8-12):1, the rotation speed is 200-400 r / min, the calcination temperature is 400-600℃, and the calcination time is 4-8 hours.

[0019] Furthermore, in step S4, the amount of boehmite used is 5-20 wt%; the amount of concentrated nitric acid used is 1-3 wt%; and the extrusion aid is hydroxypropyl methylcellulose, with an amount of 1-3 wt%.

[0020] Furthermore, in step S4, the calcination temperature is 350-400℃ and the time is 4-8h.

[0021] Secondly, the present invention provides a Co-based catalyst for nitrile hydrogenation, which is achieved by the following technical solution.

[0022] A Co-based catalyst for nitrile hydrogenation prepared by the above preparation method.

[0023] Thirdly, the present invention provides an application of a Co-based catalyst for nitrile hydrogenation, which is achieved by the following technical solution.

[0024] Application of the above-mentioned Co-based catalyst for nitrile hydrogenation in the reaction of nitrile hydrogenation to primary amine.

[0025] Furthermore, the hydrogenation of nitrile to produce primary amines includes the hydrogenation of benzonitrile, 3-cyclohexylaminopropionitrile, or isophthalonitrile.

[0026] Specifically, the evaluation conditions for the hydrogenation reaction of benzonitrile, 3-cyclohexylaminopropionitrile, or isophthalonitrile to produce primary amines are as follows:

[0027] (1) Reaction temperature: 70-120℃;

[0028] (2) Reaction pressure: 1-8 MPa;

[0029] (3) Hydrogen / Nitrile = 10-50 / 1 (m / m);

[0030] (4) Volume hourly space velocity (VHSV) of the reaction solution: 0.5-1.5 h⁻¹ -1 ;

[0031] (5) Reactant concentration: 5-40 wt%.

[0032] Furthermore, the hydrogenation of nitrile to produce primary amines is carried out under one or more of the following conditions: fixed bed, fluidized bed, and moving bed.

[0033] Furthermore, the nitrile hydrogenation Co-based catalyst is reduced at 300-600℃ for 4-8 hours before use, with a heating rate of 1-5℃ / min.

[0034] This application has the following beneficial effects.

[0035] (1) This invention utilizes the strong interaction between the unremoved template agent and the metal precursor, combined with the large specific surface area of ​​the mesoporous structure, to promote the uniform dispersion of active Co sites and enhance the reactivity of nitrile hydrogenation to produce primary or secondary amines.

[0036] (2) By doping the carrier with alkali metal Mg to adjust the acidity and alkalinity of the carrier, and combining this with metal doping, the adsorption of alkaline amines on the catalyst surface can be effectively reduced, the desorption of products can be accelerated, the occurrence of side reactions can be reduced, and the selectivity can be improved. Moreover, the present invention can avoid the addition of alkaline inhibitors and reduce the amount of waste gas and solid waste generated.

[0037] (3) The synthesis steps of this invention are simple and easy to operate. The ball milling is carried out directly without removing the template agent, which can reduce the calcination process and reduce energy consumption. In addition, the use of ball milling can reduce the amount of water used in catalyst synthesis and reduce wastewater.

[0038] In summary, the Co-based catalyst for nitrile hydrogenation provided by this invention exhibits high reactivity and product selectivity, as well as good catalyst lifetime, and has promising prospects for industrial application. Detailed Implementation

[0039] The present patent application will be further described below with reference to the embodiments.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used in the following preparation examples and examples are commercially available unless otherwise specified.

[0041] The Raney Ni catalyst used in the comparative example of this application is a Ni-Al alloy, CAS number 12003-78-0;

[0042] The copper chromite catalyst used in the comparative example of this application has the CAS number 12018-10-9.

[0043] Example 1

[0044] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-600 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 80℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co and Mo nitrates (60g total salts added, Co:Mo = 8:1, M:M), with a ball-to-material ratio of 8:1 and a rotation speed of 200 r / min. After ball milling, the mixture was calcined in a muffle furnace at 400℃ for 4 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo / Al₂O₃-Mg catalyst. The obtained catalyst was reduced at 300℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C₁. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0045] Example 2

[0046] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-800 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 80℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co and Mo nitrates (60g total salts added, Co:Mo = 8:1, M:M), with a ball-to-material ratio of 8:1 and a rotation speed of 200 r / min. After ball milling, the mixture was calcined in a muffle furnace at 400℃ for 4 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo / Al2O3-Mg catalyst. The obtained catalyst was reduced at 300℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C2. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0047] Example 3

[0048] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-1000 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 80℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co and Mo nitrates (60g total salts added, Co:Mo = 8:1, M:M), with a ball-to-material ratio of 8:1 and a rotation speed of 200 r / min. After ball milling, the mixture was calcined in a muffle furnace at 400℃ for 4 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo / Al2O3-Mg catalyst. The obtained catalyst was reduced at 300℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C3. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0049] Example 4

[0050] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-10000 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 80℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co and Mo nitrates (60g total salts added, Co:Mo = 8:1, M:M), with a ball-to-material ratio of 8:1 and a rotation speed of 200 r / min. After ball milling, the mixture was calcined in a muffle furnace at 400℃ for 4 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo / Al2O3-Mg catalyst. The obtained catalyst was reduced at 300℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C4. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0051] Example 5

[0052] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-1000 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 120℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co, Mo, and Ca nitrates (60g total salts added, Co:Mo:Ca = 8:2:1, M:M), with a ball-to-material ratio of 12:1 and a rotation speed of 400 r / min. After ball milling, the mixture was calcined in a muffle furnace at 600℃ for 8 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo-Ca / Al2O3-Mg catalyst. The obtained catalyst was reduced at 600℃ for 8 hours under hydrogen conditions to obtain the Co-based catalyst C5. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0053] Example 6

[0054] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-1000 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 100℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co, Mo, and K nitrates (60g total salts added, Co:Mo:K = 8:2:1, M:M), with a ball-to-material ratio of 8:1 and a rotation speed of 300 r / min. After ball milling, the mixture was calcined in a muffle furnace at 500℃ for 6 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo-K / Al2O3-Mg catalyst. The obtained catalyst was reduced at 400℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C6. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0055] Example 7

[0056] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-1000 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 100℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co, Mo, and Na nitrates (60g total salts added, Co:Mo:Na = 8:2:1, M:M), with a ball-to-material ratio of 8:1 and a rotation speed of 300 r / min. After ball milling, the mixture was calcined in a muffle furnace at 500℃ for 6 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo-Na / Al2O3-Mg catalyst. The obtained catalyst was reduced at 400℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C7. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0057] Example 8

[0058] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-1000 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 100℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co, Mo, and Ce nitrates (60g total salts added, Co:Mo:Ce = 8:2:1, M:M), with a ball-to-material ratio of 8:1 and a rotation speed of 300 r / min. After ball milling, the mixture was calcined in a muffle furnace at 500℃ for 6 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo-Ce / Al2O3-Mg catalyst. The obtained catalyst was reduced at 400℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C8. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0059] Example 9

[0060] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-1000 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and reacted hydrothermally at 100℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co, Mo, and Li nitrates (60g total salts added, Co:Mo:Li = 8:2:1, M:M), with a ball-to-material ratio of 8:1 and a rotation speed of 300 r / min. After ball milling, the mixture was calcined in a muffle furnace at 500℃ for 6 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo-Li / Al2O3-Mg catalyst. The obtained catalyst was reduced at 400℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C9. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0061] Example 10

[0062] 120g of Al and Mg nitrates (Al:Mg = 10:1, M:M), template agent F127 (10wt% of total weight), and 12g of dispersant PEG-1000 were dissolved in water and stirred vigorously for 4 hours. Ammonia was then added to adjust the pH to 7. The solution was transferred to a hydrothermal reactor and hydrothermally reacted at 100℃ for 24 hours. After filtration, washing, and drying, the Al₂O₃-Mg support containing the template agent was ball-milled with Co, Mo, and Mn nitrates (60g total salts added, Co:Mo:Mn = 8:2:1, M:M) at a ball-to-material ratio of 8:1 at a rotation speed of 300 r / min. After ball milling, the mixture was calcined in a muffle furnace at 500℃ for 6 hours to obtain the catalyst precursor. The catalyst precursor was kneaded with 10g of boehmite, 6.2g of concentrated nitric acid, and 3g of hydroxypropyl methylcellulose, then extruded, dried, and calcined at 400℃ to obtain a Co-Mo-Mn / Al2O3-Mg catalyst. The obtained catalyst was reduced at 400℃ for 4 hours under hydrogen conditions to obtain the Co-based catalyst C10. After activation, the catalyst was evaluated for the hydrogenation of nitriles to primary amines.

[0063] Comparative Example 1

[0064] The reaction of hydrogenating nitrile to primary amine was evaluated using a commercial fixed-bed Raney Ni catalyst (C11).

[0065] Comparative Example 2

[0066] The reaction of hydrogenating nitriles to primary amines using a commercial copper chromite catalyst (C12) was evaluated.

[0067] Application Example 1

[0068] 30 ml of catalyst (C1-C12) with a size of 20-40 mesh was loaded into a fixed-bed reactor. H2 was introduced, and the temperature was raised to 400 °C to reduce the catalyst. The pressure was 3 MPa and the space velocity was 8000 mL / h. -l g -1 The reaction time was 6 hours. The feed was switched to a 20 wt% benzonitrile-methanol solution, with a nitrile / H2 ratio of 1 / 17 (m / m), and the liquid hourly space velocity (LHSV) was 1.0 h⁻¹. -l The reaction products were analyzed online using gas chromatography and quantitatively analyzed using an FID detector. The experimental results are shown in Table 1.

[0069] Table 1. Evaluation of the catalytic performance of benzonitrile hydrogenation reaction

[0070]

[0071] The above experimental results show that the catalyst C5 modified with PEG-1000 and Ca doping has good reaction performance in this reaction, with a benzonitrile conversion rate of 99.99%, a benzylamine selectivity of more than 95%, and a dibenzylamine content of 4.39%.

[0072] Application Example 2

[0073] 30 ml of catalyst (C1-C12) with a size of 20-40 mesh was loaded into a fixed-bed reactor. H2 was introduced, and the temperature was raised to 400 °C to reduce the catalyst. The pressure was 3 MPa and the space velocity was 8000 mL / h. -l g -1 The reaction time was 6 hours. After activation, the temperature was lowered to 80°C, and the feed was switched to a 20 wt% 3-cyclohexylaminopropionitrile-ethanol solution, with a nitrile / H2 ratio of 1 / 17 (m / m) and a liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -l The reaction products were analyzed online using gas chromatography and quantitatively analyzed using an FID detector. The experimental results are shown in Table 2.

[0074] Table 23 - Performance Evaluation of Hydrogenation Catalysis of Cyclohexylaminopropionitrile

[0075]

[0076] The above experimental results show that the catalysts in Examples 1-10 of this invention have high activity and product selectivity of about 96%. In industrial production, the catalysts can be selected based on the overall catalyst preparation cost.

[0077] Application Example 3

[0078] 30 ml of catalyst (C1-C12) with a size of 20-40 mesh was loaded into a fixed-bed reactor. H2 was introduced, and the temperature was raised to 400 °C to reduce the catalyst. The pressure was 3 MPa and the space velocity was 8000 mL / h. -l g -1 The reaction time was 6 hours. After activation, the temperature was lowered to 80°C, and the feed was switched to a 10 wt% isophthalonitrile methanol-toluene solution, with a nitrile / H2 ratio of 1 / 17 (m / m). The volume hourly space velocity (VHSV) of the reaction solution was 1.0 h⁻¹. -l The reaction products were analyzed online using gas chromatography and quantitatively analyzed using an FID detector. The experimental results are shown in Table 3.

[0079] Table 3. Evaluation of the catalytic performance of isophthalonitrile hydrogenation reaction

[0080]

[0081]

[0082] The above experimental results show that the K-modified catalyst has a high conversion rate (99.8%) and product selectivity (97%).

[0083] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing a Co-based catalyst for nitrile hydrogenation, characterized in that: Includes the following steps: S1. Dissolve the soluble salts of Al and Mg, the template agent, and the dispersant in water, stir, and then add ammonia water; S2. The obtained solution was subjected to a hydrothermal reaction, and after filtration, washing, and drying, a mesoporous Al2O3-Mg support containing a template agent was obtained. S3. Mesoporous Al2O3-Mg support is ball-milled and calcined with nitrates of Co, Mo, and M to obtain a catalyst precursor; wherein M is a metal promoter. S4. The catalyst precursor is kneaded with boehmite, concentrated nitric acid and extrusion aid, then extruded and dried to obtain the Co-Mo-M / Al2O3-Mg catalyst.

2. The method for preparing a Co-based catalyst for nitrile hydrogenation according to claim 1, characterized in that: The content range of metal elements is as follows: Co content is 20-50 wt%; Mo content is 5-10 wt%; the metal additives are selected from one or more of Ca, K, Na, Ce, Li and Mn, with a content of 0-5 wt%; Al2O3-Mg is a Mg-doped mesoporous alumina carrier with a content of 45-75 wt%, of which the Mg content is 1-5 wt%.

3. The method for preparing a Co-based catalyst for nitrile hydrogenation according to claim 1, characterized in that: In step S1, the soluble salts of Al and Mg are selected from one or more of nitrates, sulfates, and chlorides.

4. The method for preparing a Co-based catalyst for nitrile hydrogenation according to claim 1, characterized in that: In step S1, the dispersant is selected from one or more of PEG-600, PEG-800, PEG-1000, and PEG-10000, with an amount of 5-25 wt%; the template agent is selected from F127, with an amount of 5-20 wt%; and ammonia is added to bring the pH to 7-10.

5. The method for preparing a Co-based catalyst for nitrile hydrogenation according to claim 1, characterized in that: In step S2, the hydrothermal reaction temperature is 80-120℃, the time is 12-24h, and the drying temperature is 80-120℃.

6. The method for preparing a Co-based catalyst for nitrile hydrogenation according to claim 1, characterized in that: In step S3, the ball milling time is 6-12 hours, the ball-to-material ratio is (8-12):1, the rotation speed is 200-400 r / min, the calcination temperature is 400-600℃, and the calcination time is 4-8 hours.

7. The method for preparing a Co-based catalyst for nitrile hydrogenation according to claim 1, characterized in that: In step S4, the amount of pseudoboehmite is 5-20 wt%; the amount of concentrated nitric acid is 1-3 wt%; the extrusion aid is hydroxypropyl methylcellulose, with an amount of 1-3 wt%; the calcination temperature is 350-400℃, and the time is 4-8 h.

8. A nitrile hydrogenation Co-based catalyst prepared by any one of the preparation methods of claims 1-7.

9. The application of the Co-based catalyst for nitrile hydrogenation according to claim 8 in the reaction of nitrile hydrogenation to primary amine.

10. The application according to claim 9, characterized in that: Before use, the Co-based catalyst for nitrile hydrogenation is reduced at 300-600℃ for 4-8 hours with a heating rate of 1-5℃ / min.

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