阅读说明：本技术 一种改性金属负载催化剂、二氨基二环己基甲烷产品及其制备方法和应用 (Modified metal supported catalyst, diaminodicyclohexylmethane product, and preparation method and application thereof ) 是由 李鑫 孙家家 张聪颖 智丁未 刘志鹏 张兵 初长坤 于 2020-07-09 设计创作，主要内容包括：本发明涉及一种改性金属负载催化剂、二氨基二环己基甲烷产品及其制备方法和应用,所述改性金属负载催化剂通过使用氨基锂对金属负载催化剂进行改性而成。将本发明的改性金属负载催化剂用于催化二氨基二苯基甲烷加氢方法,可以有效的提高产物中脂环胺产品的含量,避免仲胺副产以及PACM-OH的大量增加,并有效降低产品中反反异构体的比例,极大降低了每批次产物中仲胺副产的含量至2％以下,并解决了催化剂套用次数增加导致催化剂与产品液过滤分离时间显著增加的问题,催化剂套用40批次后,过滤时间维持在40分钟以内,极大提高了产品收率和生产效率。(The invention relates to a modified metal supported catalyst, a diaminodicyclohexylmethane product, a preparation method and application thereof. The modified metal-supported catalyst is used for catalyzing the hydrogenation method of diaminodiphenylmethane, the content of alicyclic amine products in the products can be effectively improved, the secondary amine by-products and PACM-OH are prevented from being greatly increased, the proportion of trans-isomer in the products is effectively reduced, the content of the secondary amine by-products in each batch of products is greatly reduced to below 2%, the problem that the filtration and separation time of the catalyst and product liquid is remarkably increased due to the increase of the application times of the catalyst is solved, the filtration time is maintained within 40 minutes after the catalyst is applied to 40 batches, and the product yield and the production efficiency are greatly improved.)

1. A modified metal-supported catalyst, characterized in that the modified metal-supported catalyst is obtained by modifying a metal-supported catalyst with lithium amide.

2. The modified metal supported catalyst of claim 1, wherein the metal supported catalyst comprises a combination of a metal and a support;

preferably, the metal comprises any one or a combination of at least two of the group VIIIB metals;

preferably, the metal comprises any one or a combination of at least two of Pt, Rh, Ru, Ir or Pd, preferably Rh;

preferably, the carrier comprises any one or a combination of at least two of rare earth, diatomite, alumina, activated carbon, lithium aluminate, spinel, silica or silica-alumina oxide, preferably alumina;

preferably, the metal-supported catalyst comprises Rh/Al₂O₃；

Preferably, the metal is present in an amount of 3 to 6 wt%, preferably 4 to 5 wt%, based on the weight of the metal supported catalyst.

3. The modified metal supported catalyst according to claim 1 or 2, characterized in that the modification is performed with lithium amide in an amount of 1-10 wt. -%, preferably 5-8 wt. -%, based on the weight of the metal supported catalyst.

4. A diaminodicyclohexylmethane product obtained by the hydrogenation reaction of a diaminodiphenylmethane feedstock using a modified metal catalyst according to any one of claims 1 to 3;

preferably, the diaminodicyclohexylmethane product has a secondary amine by-product content of 2% or less.

5. A process for the preparation of a diaminodicyclohexylmethane product according to claim 4, characterized in that it comprises: and (2) charging lithium amide, a metal supported catalyst and a diaminodiphenylmethane raw material into a reactor, and carrying out hydrogenation reaction to obtain the diaminodicyclohexylmethane product.

6. The process according to claim 5, wherein the diaminodiphenylmethane feedstock comprises the following components, based on the total weight of the diaminodiphenylmethane feedstock: 80-100 wt% of 4,4' -diaminodiphenylmethane, 0-18 wt% of 2,4' -diaminodiphenylmethane, 0-1 wt% of N-methyl-4, 4' -diaminodiphenylmethane and 0-1 wt% of impurities;

preferably, the diaminodiphenylmethane feedstock comprises, based on the total weight of the diaminodiphenylmethane feedstock: 84.5-99.5 wt% of 4,4' -diaminodiphenylmethane, 0-15 wt% of 2,4' -diaminodiphenylmethane, 0-0.4 wt% of N-methyl-4, 4' -diaminodiphenylmethane and 0-0.1 wt% of impurities;

preferably, the impurities comprise monoaminodiphenylmethane.

7. The method according to claim 5 or 6, wherein the lithium amide is added in an amount of 1 to 10 wt%, preferably 5 to 8 wt%, based on the weight of the metal-supported catalyst;

preferably, the amount of the metal supported catalyst added is 0.5 to 5 wt%, preferably 1 to 3 wt%, and more preferably 1.5 to 2 wt% of the total weight of the diaminodiphenylmethane feedstock.

8. The production method according to any one of claims 5 to 7, wherein the hydrogenation reaction is carried out in the presence of a solvent or in the absence of a solvent;

preferably, the hydrogenation reaction is carried out in the presence of a solvent, the concentration of the solvent being from 30 to 60 wt%, preferably from 40 to 50 wt%, based on the total weight of the diaminodiphenylmethane feedstock and solvent;

preferably, the solvent comprises any one or a combination of at least two of cyclohexane, dioxane, tetrahydrofuran, cyclohexylamine, dicyclohexylamine, methanol, ethanol, isopropanol, n-butanol, 2-butanol or methylcyclohexane.

9. The preparation method according to any one of claims 5 to 8, wherein the temperature of the hydrogenation reaction is 100-250 ℃, preferably 150-200 ℃, and more preferably 170-190 ℃;

preferably, the absolute pressure of the hydrogenation reaction is 3-15MPa, preferably 5-10MPa, and more preferably 6-8 MPa;

preferably, the reactor comprises a batch autoclave reactor with a catalyst filtration unit;

preferably, the catalyst filtering device is an internal filter or an external filter, and preferably an autoclave internal filter.

10. Use of a diaminodicyclohexylmethane product according to claim 4, characterised in that it is used for the synthesis of isocyanates or as an epoxy hardener.

Technical Field

The invention relates to the technical field of benzene ring hydrogenation, in particular to a modified metal supported catalyst, a diaminodicyclohexylmethane product, and a preparation method and application thereof.

Background

Diaminodicyclohexylmethane (PACM for short) has three stereoisomers with different thermodynamic properties of trans-trans, cis-trans and cis-cis. Wherein PACM20 refers to PACM products having a trans-isomer content of about 20 weight percent, and is used primarily in the fields of isocyanate synthesis and epoxy curing agents. Due to the stability and steric hindrance effect of the aromatic ring, the hydrogenation difficulty of diaminodiphenylmethane (abbreviated as MDA) is high. Most patents use supported noble metal catalysts to perform batch catalytic reactions at high temperature and high pressure in stirred tank reactors or fixed bed reactors to obtain satisfactory yields and anti-reaction ratios.

According to literature research, the MDA hydrogenation reaction mainly adopts a noble metal-loaded catalyst in a fixed bed or an autoclave type reactor to obtain higher product yield and lower trans-isomer ratio. Because the cost of the noble metal catalyst is high, the catalyst needs to be continuously recycled and reused so as to reduce the production cost. However, as the number of times of catalyst application increases, the channels and active sites on the surface of the catalyst are covered by more high-boiling-point tar, so that the activity and selectivity of the catalyst are gradually weakened, and further more secondary amine tar is generated and the reverse isomer is continuously increased. Meanwhile, the catalyst is wrapped by viscous tar, so that the filtering time of the catalyst from the reactor is prolonged by times, even the catalyst is taken out in advance and retired, and the production efficiency and the operation cost are greatly reduced. For an industrial device, the tar content of high-boiling-point secondary amine generated in the reaction process is reduced, so that the yield of a main product can be improved, and higher profit is obtained; on the other hand, the activity and the selectivity of the catalyst can be maintained, the content of the low trans-isomer can be controlled, and the production cost can be reduced.

US4754070 discloses a novel process by which a trans-trans isomer ratio of 17-24% can be obtained. In the method, 0.1-15 wt% of alkali modified catalyst is added before catalytic reaction to modify the supported rhodium-ruthenium double-component catalyst. US6075167 provides a ruthenium-catalyzed aromatic diamine compound reduction process with metal nitrite as promoter, which improves the reaction rate and reduces the generation of high-boiling point by-product tar. US3697449 modifies the supported ruthenium catalyst with 1-35% aqueous solution of alkali metal alkoxide or hydroxide, and then performs a hydrogenation reduction reaction of MDA.

US3856862 adopts immobilized Rh/Al₂O₃Is used as a catalyst and maintains the partial pressure of ammonia to be 10 percent to 42 percent based on the total reaction pressure, and semi-continuous hydrogenation reaction of 4,4' -MDA is carried out. US5981801 uses Ru as catalyst and active carbon, calcium carbonate or alumina as carrier, and before catalytic reaction, the catalyst is pretreated with air or oxygen at 50-200 deg.C, and then the catalytic reaction of aromatic diamine is carried out.

In order to inhibit the increase of the content of secondary amine as a byproduct, the prior art mainly adopts two measures for modifying the noble metal-supported catalyst: firstly, modifying a catalyst by adopting an aqueous solution of alkali metal alkoxide, nitrite or hydroxide; firstly, the ammonia partial pressure of a reaction system is improved, and ammonia is utilized to inhibit the occurrence of the deamination reaction. The prior art has the following defects:

1) when the modification is carried out using an alkali metal salt, it is inevitably necessary to add a small amount of water, dissolve and dilute the alkali metal salt in order to secure a better modification effect. And in the presence of a catalytic system, MDA and water can perform substitution reaction, and hydroxyl in the water can substitute amino in diaminodicyclohexylmethane to form PACM-OH. The boiling point of the product is close to PACM-OH, and the product is difficult to purify in a rectification mode, so that the production cost is greatly improved.

2) When ammonia is used for modification, the secondary reaction equilibrium for generating secondary amine is shifted to the left by increasing the partial pressure of ammonia, so that the formation of high-boiling-point secondary amine is inhibited. The introduction of large amounts of ammonia in industrial plants can lead to corrosion of the equipment and potential safety hazards. Meanwhile, ammonia gas needs to be recovered and analyzed in the post-treatment process, so that the process and equipment investment are increased.

Therefore, there is a need in the art to develop a method for hydrogenating diaminodiphenylmethane with low secondary amine content and low trans-isomer, while overcoming the above-mentioned disadvantages of the existing modification methods.

Disclosure of Invention

One of the purposes of the invention is to provide a modified metal-supported catalyst, which can catalyze diaminodiphenylmethane to carry out hydrogenation reaction to prepare diaminodicyclohexylmethane, and can effectively reduce formation of four or more secondary amine by-products and PACM-OH generated in the hydrogenation reaction process of diaminodiphenylmethane, thereby improving the content of alicyclic amine products in the products, effectively reducing the proportion of trans-trans isomers in the products, prolonging the activity of the catalyst, and improving the production efficiency and benefit.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a modified metal-supported catalyst, which is obtained by modifying a metal-supported catalyst by using lithium amide.

Compared with alkali metal nitrate or hydroxide, the lithium amide has better oil solubility, can realize good modification effect without adding extra water, improves the content of alicyclic amine products in the products, avoids the increase of secondary amine by-products and PACM-OH in a large amount, and effectively reduces the proportion of trans-trans isomers in the products. On the other hand, at the high temperature of the catalytic system, the lithium amide can adsorb residual moisture in the raw material and the solvent system, and simultaneously, the lithium amide and the water undergo a chemical reaction to generate lithium hydroxide and ammonia gas, so that the catalyst is continuously modified while the moisture of the system is further reduced, and the reaction performance of the catalyst is greatly improved.

In addition, the catalyst is applied to hydrogenation reaction, has low requirements on equipment, reduces the production cost and does not bring about potential safety hazard.

Preferably, the metal supported catalyst comprises a combination of a metal and a support.

Preferably, the metal comprises any one or a combination of at least two of the group VIIIB metals.

Preferably, the metal comprises any one or a combination of at least two of Pt, Rh, Ru, Ir or Pd, preferably Rh.

Preferably, the support comprises any one or a combination of at least two of rare earth, diatomaceous earth, alumina, activated carbon, lithium aluminate, spinel, silica or silica alumina, preferably alumina.

In the invention, the alumina is preferably used as a carrier of the catalyst, and is an amphoteric oxide, and simultaneously has weak acid and weak base properties, so that the alumina can react with lithium amide to reduce the specific surface area of the alumina properly, thereby improving the selectivity of the catalyst while properly reducing the activity of the catalyst and further reducing the content of secondary amine by-product. On the other hand, lithium amide reacts with moisture in a reaction system at the reaction temperature, so that the water content of the reaction system is reduced, the PACM-OH content is reduced, and meanwhile, lithium hydroxide and ammonia gas generated by the hydrolysis of the lithium amide also have a catalyst modification effect, so that the content of alicyclic amine products in the products is further improved, and the reduction of the content of trans-isomer in the products is facilitated.

Preferably, the metal-supported catalyst comprises Rh/Al₂O₃。“Rh/Al₂O₃"means that the metal Rh is loaded with Al₂O₃A catalyst.

Preferably, the metal is present in an amount of 3 to 6 wt%, such as 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, etc., preferably 4 to 5 wt%, based on the weight of the metal supported catalyst.

Preferably, the modification is performed using lithium amide in an amount of 1 to 10 wt% (e.g., 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, etc.), preferably 5 to 8 wt%, based on the weight of the metal supported catalyst.

In the present invention, the amount of lithium amide is further preferably selected within a preferred range, and the catalyst exhibits optimum activity, and the effect of reducing the content of by-products and the proportion of anti-trans isomers is most excellent, and the effect is deteriorated when the content is too high or too low.

The second purpose of the invention is to provide a diaminodicyclohexylmethane product, which is obtained by catalyzing diaminodiphenylmethane raw materials to carry out hydrogenation reaction by using the modified metal catalyst of the first purpose.

Preferably, the diaminodicyclohexylmethane product has a secondary amine by-product content of 2% or less, e.g., 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, etc.

The contents referred to in the invention are mass contents, and the base number is the total mass of the diaminodicyclohexyl methane product.

The invention also aims to provide a preparation method of the diaminodicyclohexyl methane product, which comprises the following steps: and (2) charging lithium amide, a metal supported catalyst and a diaminodiphenylmethane raw material into a reactor, and carrying out hydrogenation reaction to obtain the diaminodicyclohexylmethane product.

The invention provides a method for obtaining high content of alicyclic amine, low content of secondary amine and low proportion of trans-isomer, which greatly reduces the content of secondary amine by-products in each batch of products to be below 2%, solves the problem that the filtration and separation time of catalyst and product liquid is obviously increased due to the increase of the application times of the catalyst, maintains the filtration time within 40 minutes after the catalyst is applied for 40 batches, and greatly improves the product yield and the production efficiency.

Preferably, the diaminodiphenylmethane feedstock comprises, based on the total weight of the diaminodiphenylmethane feedstock: 80-100 wt% (e.g., 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, etc.) of 4,4 '-diaminodiphenylmethane, 0-18 wt% (e.g., 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, etc.) of 2,4' -diaminodiphenylmethane, 0-1 wt% (e.g., 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, etc.) of N-methyl-4, 4' -diaminodiphenylmethane and 0-1 wt% (e.g., 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, etc.) of impurities. The impurities refer to substances other than 4,4' -diaminodiphenylmethane, 2,4' -diaminodiphenylmethane and N-methyl-4, 4' -diaminodiphenylmethane.

Preferably, the diaminodiphenylmethane feedstock comprises, based on the total weight of the diaminodiphenylmethane feedstock: 84.5-99.5 wt% of 4,4' -diaminodiphenylmethane, 0-15 wt% of 2,4' -diaminodiphenylmethane, 0-0.4 wt% of N-methyl-4, 4' -diaminodiphenylmethane and 0-0.1 wt% of impurities.

Preferably, the impurities comprise monoaminodiphenylmethane.

Preferably, the lithium amide is added in an amount of 1 to 10 wt% (e.g., 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, etc.), preferably 5 to 8 wt%, based on the weight of the metal-supported catalyst.

Preferably, the metal supported catalyst is added in an amount of 0.5 to 5 wt%, such as 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, etc., based on the total weight of the diaminodiphenylmethane feedstock, preferably 1 to 3 wt%, and more preferably 1.5 to 2 wt%.

Preferably, the hydrogenation reaction is carried out with a solvent or without a solvent.

Preferably, the hydrogenation reaction is carried out in the presence of a solvent at a concentration of 30 to 60 wt.%, such as 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, etc., preferably 40 to 50 wt.%, based on the total weight of the diaminodiphenylmethane feedstock and solvent.

Preferably, the solvent comprises any one or a combination of at least two of cyclohexane, dioxane, tetrahydrofuran, cyclohexylamine, dicyclohexylamine, methanol, ethanol, isopropanol, n-butanol, 2-butanol or methylcyclohexane.

Preferably, the hydrogenation reaction temperature is 100-.

Preferably, the absolute pressure of the hydrogenation reaction is 3 to 15MPa, for example, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, etc., preferably 5 to 10MPa, and more preferably 6 to 8 MPa.

Preferably, the reactor comprises a batch autoclave reactor with a catalyst filtration unit,

preferably, the catalyst filtering device is an internal filter or an external filter, and preferably an autoclave internal filter.

The fourth purpose of the invention is to provide an application of the diaminodicyclohexylmethane product in the second purpose, wherein the diaminodicyclohexylmethane product is applied to the synthesis of isocyanate or used as an epoxy curing agent.

Compared with the prior art, the invention has the following beneficial effects:

(1) the modified metal catalyst provided by the invention can effectively improve the content of alicyclic amine products in the products, avoid the increase of secondary amine by-products and PACM-OH in a large amount, effectively reduce the proportion of trans-isomer in the products, and simultaneously, the lithium amide can adsorb residual moisture in raw materials and a solvent system and simultaneously chemically react with water to generate lithium hydroxide and ammonia gas, so that the catalyst is continuously modified while the moisture of the system is further reduced, and the reaction performance of the catalyst is greatly improved. In addition, the requirement on equipment is not high, and potential safety hazards are avoided.

(2) The hydrogenation method provided by the invention can obtain high content of alicyclic amine, low content of secondary amine and low proportion of trans-isomer, greatly reduces the content of secondary amine by-products in each batch of products, can be reduced to below 2%, solves the problem that the filtration and separation time of the catalyst and the product liquid is obviously increased due to the increase of the catalyst application times, and greatly improves the product yield and the production efficiency because the filtration time is maintained within 40 minutes after the catalyst is applied to 40 batches.

(3) The hydrogenation method provided by the invention can specifically obtain the following effects: the conversion rate of the diaminodiphenylmethane raw material is 98-100%, and in the final product, H₁₂The content of MDA is more than or equal to 97 percent, the content of secondary amine is less than or equal to 2 percent, the content of PACM-OH is less than or equal to 0.3 percent, the content of other anti-isomer is less than or equal to 1 percent, and simultaneously, the content of anti-isomer is controlled within 17.5 percent, compared with the modification without lithium amide, H₁₂The MDA content can be improved by about 8 percent.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The starting materials used in the following examples or comparative examples, unless otherwise specified, are commercially available technical grade conventional materials, and the main materials and test equipment information are as follows:

4wt％Rh/Al₂O₃purchased from Zhuangxinwan corporation, 4 wt% refers to the metal content, the same principle as follows.

4 wt% Rh/silica was purchased from Zhuangxinwan corporation.

5wt％Rh/Al₂O₃Purchased from Zhuangxinwan corporation.

3wt％Rh/Al₂O₃Purchased from Zhuangxinwan corporation.

6wt％Rh/Al₂O₃Purchased from Zhuangxinwan corporation.

Lithium amide was purchased from the alatin reagent with a purity of 95%.

Tetrahydrofuran was purchased from Kemi Europe and was analytically pure.

MDA-100 is from Wanhua WANAMINE MDA-100. Wherein the content of 4,4'-MDA is 99.5 wt%, the content of N-methyl-4, 4' -MDA is 0.35 wt%, and the content of monoaminodiphenylmethane is 0.15 wt%.

MDA-85 is from Wanhua WANAMINE MDA-85. Wherein the content of 2,4' -MDA is 15 wt%, the content of 4,4' -MDA is 84.5 wt%, the content of N-methyl-4, 4' -MDA is 0.35 wt%, and the content of monoaminodiphenylmethane is 0.15 wt%.

The gas chromatography is 7890 series of Agilent, DB-5 capillary chromatographic column, FID detector temperature is 300 deg.C, initial column temperature is 160 deg.C, 10 deg.C/min is increased to 300 deg.C, and the time is 20 min.