Preparation method and application of hydrogenation catalyst

Abstract

The invention provides a hydrogenation catalyst. The catalyst comprises a carrier alumina and an active component ruthenium attached to the carrier. The particle size D10 of the carrier is less than 10 microns, the particle size D50 is 30-60 microns, and the particle size D90 is 120-150 microns. After the catalyst is screened according to D50, the fine-particle-size catalyst is used for preparing low-trans HMDA through an MDA hydrogenation reaction, the coarse-particle-size catalyst is used for preparing high-trans HMDA through an MDA hydrogenation reaction, the MDA conversion rate is 100%, the HMDA yield reaches 95% or above, no heavy-component tar exists, and no obvious inactivation exists after the catalyst is used for 60 batches.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst materials, and in particular to a noble metal catalyst for preparing 4,4'-diaminodiphenylmethane (4,4'-MDA) by hydrogenating 4,4'-diaminodicyclohexylmethane (4,4'-HMDA), and a preparation method thereof. Background Art

[0002] 4,4'-MDA is subjected to high pressure catalytic hydrogenation to obtain 4,4'-diaminodicyclohexylmethane, which is a mixture of three isomers: cis-cis, cis-trans and trans-trans. Different isomer ratios determine the application value. When the content of trans-trans isomer is less than 24%, that is, PACM20, it is one of the raw materials for preparing 4,4'-dicyclohexylmethane diisocyanate (4,4'-HMDI). This isocyanate has unique yellowing resistance and weather resistance and is an important intermediate in the polyurethane and polyamide industries. In addition, PACM20 is also used as an amine epoxy curing agent. With economic development, its demand in the domestic and foreign markets has increased year by year.

[0003] Patent US6075167 discloses a ruthenium-catalyzed reduction process of aromatic diamine compounds using metal nitrite as a modifier, which increases the reaction rate and reduces the high-boiling point tar byproduct. The large amount of metal nitrite added is not conducive to the recovery of precious metals and causes waste.

[0004] Patent CN114082428A discloses a supported Ru-Re bimetallic catalyst with highly uniformly dispersed active components prepared by a special "double solvent" impregnation method. When the catalyst is used for catalytic hydrogenation of aromatic diamine compounds, a certain amount of organic compounds such as acetonitrile, propionitrile, butyronitrile, etc. are added to the reaction system, which can significantly shorten the tailing time of the hydrogenation reaction, improve the reaction efficiency, and help inhibit catalyst deactivation.

[0005] Patent CN114870884A discloses a catalyst which uses boron nitride obtained through a specific preparation process as a carrier and metallic ruthenium as an active component to achieve high-activity and high-selectivity one-step hydrogenation conversion of aromatic amines into alicyclic amines under mild conditions, thereby solving the problems of low catalyst stability and a large number of deamination and demethylamine by-products. The activity of the catalyst is only used for 200 hours, and a specific carrier is required for the preparation of the catalyst.

[0006] Patent CN104788323A discloses a method for synthesizing 1,4-cyclohexyldimethylamine by hydrogenation of p-phenylenediamine using a catalyst supported by activated carbon. The reaction requires the additional addition of alkali metal additives, such as LiOH, NaOH, etc. Although the selectivity of this catalyst is good, it is inevitable to add alkaline additives to suppress the occurrence of side reactions, which will also cause the catalyst stability to decrease.

[0007] CN111804324A discloses a method in which the addition of lithium amide can reduce the ratio of trans-isomers in the product and improve the product selectivity. By reacting with water to generate LiOH and NH3, the catalyst is subjected to secondary modification to improve the product selectivity. However, the secondary modification further destroys the support structure, resulting in a reduction in the catalyst life.

[0008] CN108440311A discloses a method for preparing diaminodicyclohexylmethane by hydrogenation reaction by introducing hydrogen containing carbon monoxide. The method can effectively reduce the by-product of tetracyclic and higher secondary amines generated during the hydrogenation reaction of diaminodiphenylmethane, and effectively reduce the ratio of trans-trans isomers in the product, thereby increasing the yield of alicyclic amine products, prolonging the activity of catalysts, and improving production efficiency and benefits.

[0009] CN106631826A discloses a method of reducing the generation of high-boiling tar during MDA hydrogenation by adding phenolic compounds, thereby improving production efficiency. However, phenolization will generate alcohol during the hydrogenation process, making separation difficult and further increasing production costs.

[0010] US20020183556A1 discloses a method for preparing a catalyst containing ruthenium on a high-purity alumina carrier. The hydrogenation reaction pressure is 10-20 MPa, and the mass fraction of PACM in the final mixture is 81-89%. The high hydrogenation reaction pressure increases the cost.

[0011] Patent US 9873658B2 discloses a method for hydrogenating MDA, using Ru / ZrO2 catalyst prepared by impregnation method to catalyze the MDA hydrogenation reaction. At 140°C, the MDA conversion rate and HMDA selectivity are 100% and 93%, respectively, but the trans-trans isomer content in the product reaches 49%. This technology is difficult to achieve both high selectivity and low trans-trans isomer content, and the catalyst has poor operating stability.

[0012] In summary, the existing technology has the following defects: when used for hydrogenation of aromatic amines, especially MDA, the catalyst has poor stability, low selectivity, many by-products, and high-boiling point tar. In order to increase the selectivity, the carrier is modified by adding additives to reduce the by-products, but the modification of the carrier will destroy the carrier structure and reduce the life of the catalyst. Alternatively, other additives such as phenols or metal salts are introduced to reduce the generation of tar and increase the selectivity, but this will also increase the difficulty of separation. Summary of the invention

[0013] The present invention aims at the deficiencies of the prior art and provides a method for preparing and using a catalyst to solve the problems of poor stability, short life and high by-products of the hydrogenation catalyst currently used in preparing alicyclic amines by hydrogenation of MDA.

[0014] In order to achieve the purpose of the present invention, the following technical solutions are adopted:

[0015] In a first aspect of the present invention, there is provided a hydrogenation catalyst, the catalyst comprising a carrier and an active component attached to the carrier;

[0016] The active component is ruthenium;

[0017] The loading amount of the active component based on the mass of the carrier is 0.1-10wt%, preferably 1-5%;

[0018] The carrier is alumina;

[0019] The aluminum oxide is one or more of γ-Al2O3, θ-Al2O3, α-Al2O3, δ-Al2O3, and β-Al2O3;

[0020] The particle size of the carrier is 0.2-200 μm. Preferably, the particle size D10 of the carrier is less than 10 μm, D50 is 30-60 μm, and D90 is 120-150 μm.

[0021] The second aspect of the present invention provides a method for preparing the hydrogenation catalyst, comprising the following steps:

[0022] (1) putting alumina into a muffle furnace and calcining at 200-500° C. for 2-6 hours to obtain a carrier for standby use; the particle size of the carrier is 0.2-200 μm, preferably, the particle size D10 of the carrier is less than 10 μm, D50 is 30-60 μm, and D90 is 120-150 μm;

[0023] (2) dissolving 2-amino-3-p-hydroxyphenylpropionic acid in water, adding the calcined carrier, stirring at 50-60° C. for 3-6 hours, and drying at 120-160° C. for 5-10 hours;

[0024] (3) dissolving the ruthenium salt in water, adding the carrier of step (2) above, and stirring at 20-80° C. for 1-4 h;

[0025] (4) After step (3), remove water and dry at 120-160° C. for 5-10 h;

[0026] (5) After drying in step (4), the catalyst is placed in a tubular reactor and reduced and activated at 180-300° C. using hydrogen as a reducing gas. After 2-6 hours, the reduced and activated catalyst is cooled and taken out for screening.

[0027] In the present invention, the mass of the 2-amino-3-p-hydroxyphenylpropionic acid in step (2) is 0.1-5% of the mass of the carrier after calcination, preferably 1-4%.

[0028] In the present invention, the ruthenium salt in step (3) includes one or more of ruthenium acetate, ruthenium nitrate or ruthenium chloride or their respective hydrates.

[0029] In the present invention, the screening method in step (5) is screening according to the catalyst particle size D50, the fine particle size catalyst is used for MDA hydrogenation reaction to prepare low trans-trans (13-16%) isomers, and the coarse particle size catalyst is used for MDA hydrogenation reaction to obtain high trans-trans (30-45%) isomers, the MDA conversion rate can reach 100%, the yield exceeds 95%, there is no heavy component tar, and the catalyst is used for 60 batches without deactivation.

[0030] The invention also relates to the application of the catalyst.

[0031] A method for preparing 4,4'-diaminodiphenylmethane (4,4'-MDA) by hydrogenating 4,4'-diaminodicyclohexylmethane (4,4'-HMDA) adopts the above catalyst, wherein when preparing low trans-trans (13-16%) isomers, a fine particle size catalyst is used, and when preparing high trans-trans (30-45%) isomers, a coarse particle size catalyst is used.

[0032] The 4,4'-MDA of the present invention is used in the form of a 4,4'-MDA solution;

[0033] The concentration of the 4,4'-MDA solution is 20-60 wt%, based on the mass of the solvent and the raw material;

[0034] The solvent is selected from one or more of ethanol, n-butanol, 2-butanol, dihydrofuran, tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and dioxane.

[0035] The reaction temperature of the present invention is 80-150°C, the reaction pressure is 3-5MPa, and the reaction time is 0.5-3h;

[0036] The amount of catalyst used is 0.1-10% of the mass of 4,4'-MDA, preferably 1-5%.

[0037] The beneficial effects of the present invention are:

[0038] In the present invention, the carrier is modified by 2-amino-3-p-hydroxyphenylpropionic acid, the steric hindrance of the phenolic hydroxyl group is small, and it is relatively easier to enter the pores of the carrier with a small particle size for modification, so that the acidity of the small particle size carrier is weaker, the anti-antibody obtained by the fine particle size catalyst after screening is lower, and the corresponding large particle size carrier is not restricted by steric hindrance. The carboxylic acid part connected to the benzene ring can modify the pores of the large particle size carrier at the same time, so the acidity of the coarse particle size carrier after screening is stronger, and the fatty amine connected to the benzene ring accelerates the desorption of the product alicyclic amine, effectively inhibiting the generation of heavy component tar.

[0039] Fine particle size catalysts are used for 4,4'-MDA hydrogenation reaction to obtain low-trans (13-16%) isomers, and coarse particle size catalysts are used for 4,4'-MDA hydrogenation reaction to obtain high-trans (30-45%) isomers. The MDA conversion rate reaches 100%, the yield exceeds 95%, there is no heavy component tar, and the catalyst has no obvious deactivation after 60 batches of application. DETAILED DESCRIPTION

[0040] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0041] MDA comes from Wanhua Chemical, with a purity of ≥99.5%. The raw materials and reagents in the following examples and comparative examples were purchased from commercial sources unless otherwise specified.

[0042] Example 1

[0043] Catalyst preparation process:

[0044] (1) Weigh 300 g of γ-Al2O3, place it in a muffle furnace, and calcine it at 300°C for 4 h. The particle size of the carrier is D10 is 9.8 μm, D50 is 40.7 μm, and D90 is 135.4 μm;

[0045] (2) Weigh 5 g of 2-amino-3-p-hydroxyphenylpropionic acid, dissolve it in 500 g of water, add 100 g of the calcined carrier, stir at 50° C. for 4 h, and dry at 120° C. for 5 h.

[0046] (3) Weigh 5.18 g of RuCl3·3H2O and dissolve it in water, add 50 g of the carrier in step (2) above, and stir at 30°C for 4 h;

[0047] (4) After step (3), remove water and dry at 120° C. for 5 h;

[0048] (5) After calcination in step (4), the catalyst is placed in a tubular reactor and reduced and activated at 300°C using hydrogen as a reducing gas. After 4 hours, the reduced and activated catalyst is cooled and taken out.

[0049] After screening according to D50, MDA hydrogenation reaction was carried out.

[0050] MDA hydrogenation reaction process:

[0051] Add 2.0g of catalyst to a 1L reactor, dissolve 4,4'-MDA in dioxane, prepare 400g of solution with a concentration of 40wt% (based on the mass of the solvent and raw materials), replace it three times with 1MPa(G) of N2, and then replace it three times with 1MPa(G) of H2. Then add H2 to 1MPa. Raise the reaction temperature to 140℃, maintain the pressure at 5MPa (if the pressure is insufficient when it rises to the reduction temperature, add hydrogen to reach the target pressure), cool down and filter after 2h, take samples for analysis (others are partial hydrogenation products and light components); the catalyst is applied. The reaction results are shown in the following table:

[0052]

[0053] Example 2

[0054] In the catalyst preparation process of Example 1, the 2-amino-3-p-hydroxyphenylpropionic acid was changed to 3 g, the RuCl3·3H2O was changed to 1.30 g, and the rest remained unchanged.

[0055] MDA hydrogenation reaction process:

[0056] The amount of catalyst added in the MDA hydrogenation reaction process in Example 1 was changed to 4 g, and the temperature was lowered and filtered after 1.5 hours, and samples were taken for analysis (the rest were part of the hydrogenation products and light components), and the rest remained unchanged. The reaction results are shown in the following table:

[0057]

[0058] Example 3

[0059] The amount of 2-amino-3-p-hydroxyphenylpropionic acid in the catalyst preparation process in Example 1 was changed to 1 g, and the rest remained unchanged.

[0060] MDA hydrogenation reaction process:

[0061] Add 1.5g of catalyst to a 1L reactor, dissolve MDA in tetrahydrofuran, prepare 300g of solution with a concentration of 50wt% (based on the mass of the solvent and raw materials), replace it three times with 1MPa(G) of N2, and then replace it three times with 1MPa(G) of H2. Then add H2 to 1MPa. Raise the reaction temperature to 120℃, maintain the pressure at 5MPa (if the pressure is insufficient when it reaches the reduction temperature, add hydrogen to reach the target pressure), cool down and filter after 3h, take samples for analysis (others are partial hydrogenation products and light components); the catalyst is applied. The reaction results are shown in the following table:

[0062]

[0063] Comparative Example 1

[0064] The catalyst preparation process is the same as in Example 1, but the catalyst is not screened during the MDA hydrogenation reaction. The rest remains unchanged. The reaction results are shown in the following table:

[0065]

[0066]

[0067] Comparative Example 2

[0068] During the catalyst preparation process, 2-amino-3-p-hydroxyphenylpropionic acid was replaced with p-hydroxyphenylpropionic acid, and the other conditions remained unchanged. The reaction results are shown in the following table:

[0069]

[0070] Comparative Example 3

[0071] During the catalyst preparation process, 2-amino-3-p-hydroxyphenylpropionic acid was replaced with phenol, and the other conditions remained unchanged. The reaction results are shown in the following table:

[0072]

[0073] Comparative Example 4

[0074] During the catalyst preparation process, 2-amino-3-p-hydroxyphenylpropionic acid was replaced with 2-amino-3-phenylpropionic acid, and the other conditions remained unchanged. The reaction results are shown in the following table:

[0075]

[0076]

[0077] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A hydrogenation catalyst, comprising a carrier and an active component attached to the carrier; The active component is ruthenium; The loading amount of the active component based on the mass of the carrier is 0.1-10wt%, preferably 1-5%; The carrier is alumina; preferably, it is selected from γ-Al2O3, θ-Al2O3, α-Al2O3, δ-Al2O3, β-Al2O3; Preferably, the particle size of the carrier is 0.2-200 μm, preferably, the particle size D10 of the carrier is less than 10 μm, D50 is 30-60 μm, and D90 is 120-150 μm.

2. The method for preparing the hydrogenation catalyst according to claim 1, comprising the steps of: (1) taking alumina and placing it in a muffle furnace, calcining it to obtain a carrier for standby use; the particle size of the carrier is 0.2-200 μm, preferably, the particle size D10 of the carrier is less than 10 μm, D50 is 30-60 μm, and D90 is 120-150 μm; (2) dissolving 2-amino-3-p-hydroxyphenylpropionic acid in water, adding the calcined carrier, stirring, and drying; (3) dissolving the ruthenium salt in water, adding the carrier from step (2) above, and stirring; (4) after step (3), remove water and dry; (5) After drying in step (4), the catalyst is placed in a tubular reactor to reduce and activate the catalyst, and the reduced and activated catalyst is taken out after cooling and sieving.

3. The preparation method according to claim 2, wherein In step (1), calcination is performed at 200-500° C. for 2-6 hours.

4. The preparation method according to claim 2, wherein In step (2), the mass of 2-amino-3-p-hydroxyphenylpropionic acid is 0.1 to 5% of the mass of the carrier after calcination, preferably 1 to 4%; Preferably, stirring is performed at 50-60° C. for 3-6 h, and drying is performed at 120-160° C. for 5-10 h.

5. The preparation method according to claim 2, wherein: In step (3), the ruthenium salt includes one or more of ruthenium acetate, ruthenium nitrate or ruthenium chloride or their respective hydrates; Preferably, stirring is carried out at 20-80°C for 1-4h.

6. The preparation method according to claim 2, wherein: In step (4), drying is performed at 120-160° C. for 5-10 hours.

7. The preparation method according to claim 2, wherein: In step (5), hydrogen is used as a reducing gas to reduce and activate the catalyst at 180-300° C. for 2-6 hours; the screening is performed according to the catalyst particle size D50.

8. A method for preparing 4,4'-diaminodiphenylmethane by hydrogenating 4,4'-diaminodiphenylmethane, using the catalyst according to any one of claims 1 to 7, and screening according to the catalyst particle size D50; wherein: When the low-trans isomer is prepared, a catalyst with a fine particle size is used, and when the high-trans isomer is prepared, a catalyst with a coarse particle size is used.

9. The preparation method according to claim 8, wherein: The 4,4'-MDA is used in the form of a 4,4'-MDA solution; the solution concentration is 20-60wt%; preferably, the solvent is selected from one or more of ethanol, n-butanol, 2-butanol, dihydrofuran, tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and dioxane.

10. The preparation method according to claim 8, wherein: The reaction temperature is 80-150°C, the reaction pressure is 3-5MPa, and the reaction time is 0.5-3h; The amount of catalyst used is 0.1-10% of the mass of 4,4'-MDA, preferably 1-5%.

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