A process for the preparation of diamines and polyamines of the diphenylmethane series

Abstract

The application provides a preparation method of diphenylmethane series diamines and polyamines. In the preparation method of the diphenylmethane series diamines and polyamines, a solid acid catalyst with an acid amount greater than 1.3 mmol / g is used as a catalyst for an aminal transposition rearrangement reaction, the selectivity of the solid acid catalyst in the aminal transposition rearrangement reaction can be significantly improved, the content of tricyclic untransposed substances in the diphenylmethane series diamines and polyamines is reduced, and then high-quality diphenylmethane diisocyanate is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic chemical industry, and relates to a preparation method of diamines and polyamines in the diphenylmethane series. BACKGROUND

[0002] Currently, the industrial production of diphenylmethane diisocyanate (MDI) includes three steps. The first step is a salt formation reaction, in which aniline reacts with hydrochloric acid to produce aniline hydrochloride. The second step is a condensation and shift reaction, in which aniline hydrochloride reacts with formaldehyde to produce diamines and polyamines (DAM) in the diphenylmethane series. The third step is a reaction to produce diphenylmethane diisocyanate. Among them, the diamines and polyamines in the diphenylmethane series in the second step product include 4,4'-diaminodiphenylmethane (MDA), which is the main component for preparing diphenylmethane diisocyanate. In the condensation and shift reaction of the second step, hydrochloric acid is usually selected as the catalyst. The amount of hydrochloric acid determines the change in the composition of the reaction product. The addition of a large amount of hydrochloric acid enables aniline and formaldehyde to react in a homogeneous phase, thereby ensuring the reaction quality. However, a large amount of hydrochloric acid present after the shift reaction needs to be neutralized by adding caustic soda, which will cause a large consumption of caustic soda. From an economic point of view, on the one hand, reducing the amount of hydrochloric acid can reduce the amount of caustic soda and lower the production cost. On the other hand, the shift reactor uses special materials with high cost. Adding a large amount of equipment or significantly increasing the reaction temperature will inevitably increase the production cost.

[0003] It has been reported in the prior art that solid acid catalysts are used to replace hydrochloric acid for catalysis. Patent CN114829000A discloses a method for heterogeneous synthesis of methylenedianiline, which involves a catalytic material that can achieve a high 4,4'-MDA isomer molar ratio. However, the use of solid acid catalysts often cannot completely shift the aminal, and the product contains a large amount of impurities such as tricyclic unshifted substances and bicyclic unshifted substances. These impurities enter the photochemical system and generate a series of by-products, resulting in low quality of diphenylmethane diisocyanate, which in turn affects the quality of downstream products such as polyurethane. The prior art can effectively reduce the content of bicyclic unshifted substances in the shift reaction product, but due to the complexity of the tricyclic shift process, the generation amount of tricyclic unshifted substances is difficult to control, and the content of tricyclic unshifted substances cannot be effectively reduced at present.

[0004] Therefore, it is of great significance to develop a preparation method of diamines and polyamines in the diphenylmethane series with low cost, which can improve the selectivity of the shift reaction and reduce the content of by-product tricyclic unshifted substances. SUMMARY

[0005] In view of the defects in the prior art, the application provides a preparation method of diphenylmethane series diamines and polyamines, which uses a solid acid catalyst with an acid amount of more than 1.3 mmol / g as a catalyst for an aminal transposition rearrangement reaction, can significantly improve the selectivity of the solid acid catalyst in the aminal transposition rearrangement reaction, reduce the content of tricyclic untransposed substances in the diphenylmethane series diamines and polyamines, and further facilitate obtaining high-quality diphenylmethane diisocyanate.

[0006] The application provides a preparation method of diphenylmethane series diamines and polyamines, which comprises the following steps:

[0007] 1) performing a dehydration condensation reaction on formaldehyde and aniline to obtain a first product system comprising an aminal;

[0008] 2) performing a purification treatment on the first product system comprising the aminal to obtain the aminal;

[0009] 3) performing a transposition rearrangement reaction on the aminal under the action of a solid acid catalyst to obtain a second product system comprising diphenylmethane series diamines and polyamines;

[0010] The acid amount of the solid acid catalyst is more than 1.3 mmol / g;

[0011] 4) performing a refining treatment on the second product system comprising the diphenylmethane series diamines and polyamines to obtain the diphenylmethane series diamines and polyamines.

[0012] In a preferred embodiment, the solid acid catalyst comprises one or more of a cation exchange resin, a molecular sieve and a super acid.

[0013] In a preferred embodiment, the acid amount of the solid acid catalyst is more than 1.4 mmol / g.

[0014] In a preferred embodiment, the catalyst has at least one desorption peak with a temperature of more than 450 DEG C, preferably more than 480 DEG C, in an NH3-TPD test.

[0015] In a preferred embodiment, the catalyst comprises at least one strong acid center.

[0016] In step 1), the dehydration condensation reaction has a temperature of 40-100 DEG C and a time of 0.2-2 h.

[0017] And / or, the molar ratio of the aniline to the formaldehyde is (0.2-0.6):1.

[0018] In a preferred embodiment, in step 3), the temperature of the transposition rearrangement reaction is 80-120℃, and the time is 1-5h.

[0019] In a preferred embodiment, in step 2), the purification treatment comprises: performing oil-water two-phase separation treatment on the first product system comprising the aminal, and collecting the organic phase; performing dehydration treatment on the organic phase, so that the water content in the organic phase is <50ppm.

[0020] In a preferred embodiment, in step 4), the refining treatment comprises sequentially performing evaporation treatment and stripping treatment on the second product system comprising the dimethylmethane series diamine and polyamine;

[0021] The pressure of the evaporation treatment is 3-15kPa, and the temperature is 180-240℃; the pressure of the stripping treatment is 5-20kPa, and the temperature is 150-210℃.

[0022] In a preferred embodiment, the content of the tricyclic untransposed substance in the diphenylmethane series polyamine is <50ppm.

[0023] The implementation of the present application has at least the following beneficial effects:

[0024] 1) The present application uses a solid acid catalyst with an acid content of >1.3mmol / g to perform transposition rearrangement reaction on the aminal, which can significantly improve the selectivity of the aminal to the diphenylmethane series diamine and polyamine, and reduce the content of untransposed substances, especially the tricyclic untransposed substance, thereby facilitating the obtaining of high-quality diphenylmethane diisocyanate.

[0025] 2) The present application uses a solid acid catalyst instead of traditional hydrochloric acid as the catalyst for the transposition rearrangement reaction of the aminal, thereby avoiding the need to add caustic soda when neutralizing the hydrochloric acid, avoiding the consumption of caustic soda, and reducing the production cost. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0027] The present application provides a preparation method of diphenylmethane series diamine and polyamine, comprising the following steps:

[0028] 1) performing dehydration condensation reaction on formaldehyde and aniline to obtain a first product system comprising an aminal;

[0029] 2) The first product system, including acetalamine, is purified to obtain acetalamine;

[0030] 3) Under the action of a solid acid catalyst, acetal amines undergo a transposition rearrangement reaction to obtain a second product system including diamines and polyamines of the diphenylmethane series;

[0031] Among them, the acid content of the solid acid catalyst is >1.3 mmol / g;

[0032] 4) The second product system, which includes diphenylmethane series diamines and polyamines, is purified to obtain diphenylmethane series diamines and polyamines.

[0033] In step 1), the dehydration condensation reaction of formaldehyde and aniline can be represented by the following reaction equation:

[0034]

[0035] Formaldehyde is used as the methylene donor, and the reaction can be carried out using a 30% to 50% aqueous formaldehyde solution, more preferably a 35% to 40% aqueous formaldehyde solution. After completing the reaction in step 1), the first product system will contain water and some byproducts in addition to the acetal amine.

[0036] The presence of moisture significantly affects the performance and lifespan of solid acid catalysts. Specifically, water molecules can cause expansion and contraction of the catalyst's pore structure and may react with acidic sites to form hydroxides. Pore structure and acidic sites are key factors influencing catalyst activity. Therefore, before using solid acid catalysts to catalyze transposition rearrangement reactions, the first product system, including acetal amines, needs to be purified to remove moisture and avoid its negative impact on the catalytic activity of the solid acid catalyst.

[0037] In step 2), the acetal rearrangement reaction under the action of a solid acid catalyst can be represented by the following reaction formula:

[0038]

[0039] Ideally, the rearrangement reaction yields bicyclic and tricyclic transposition compounds as shown in the above reaction formulas. Among them, the following isomers also belong to bicyclic transposition compounds:

[0040]

[0041] The following isomers also belong to ternary transposition substances:

[0042]

[0043] Among them, the translocated substance refers to the rearrangement of the amine after the amine is directly connected to the benzene ring in the form of a primary amine, and the untranslocated substance refers to the amino group still connected between the two benzene rings in the form of a secondary amine. For example, the bicyclic untranslocated substance includes , and the like, and the tricyclic untranslocated substance includes , When the selectivity of the rearrangement reaction is poor, there are more untranslocated substances in the product, and after entering the photochemical system, the secondary amine cannot react with phosgene to generate isocyanate, resulting in more impurities in the product, affecting the product quality.

[0044] And in the present application, by using a solid acid catalyst with an acid amount of >1.3 mmol / g to catalyze the translocation rearrangement reaction of the aminal, the selectivity of the rearrangement reaction can be significantly improved, and the content of untranslocated substances in the product can be reduced, especially the content of tricyclic untranslocated substances can be reduced to below 50 ppm. In addition, compared with traditional hydrochloric acid, the solid acid catalyst can reduce the amount of caustic soda required for subsequent neutralization of hydrochloric acid, thereby reducing production costs. After the translocation rearrangement reaction, the solid acid can be recovered and reused by simple solid-liquid separation method.

[0045] In step 4), the second product system including diamines and polyamines of the diphenylmethane series is subjected to a refining treatment mainly to remove water and light component impurities such as aniline, so as to obtain a process for obtaining a high-purity diamine and polyamine product of the diphenylmethane series. The conventional refining treatment means in the art can be used.

[0046] The type of solid acid catalyst is not specifically limited in the present application, as long as the acid amount meets the limitation, including but not limited to one or more of cation exchange resin, molecular sieve, super acid. Among them, the cation exchange resin can be a sulfonic acid-based cation exchange resin, the molecular sieve can be 4A molecular sieve, Y-type molecular sieve, modified Y-type molecular sieve, etc., and the super acid can be a heteropoly acid.

[0047] The acid amount of the solid acid refers to the number or concentration of acid sites in the solid acid material, which directly affects the selectivity and activity of the catalyst. Generally speaking, the greater the acid amount, the greater the density of acid centers, and the more the number of catalytic active sites, which is beneficial to improve the reaction rate of the catalytic reaction. Further, when the acid amount of the solid acid catalyst is >1.4 mmol / g, the selectivity of the translocation rearrangement reaction is higher, and the catalytic activity of the catalyst is better.

[0048] In the present application, the test method of the acid amount of the solid acid catalyst can use the conventional test methods in the art, such as ammonia temperature programmed desorption (NH3-TPD), titration, solid nuclear magnetic resonance, and pyridine infrared spectroscopy, etc.

[0049] In a specific embodiment, the catalyst has at least one desorption peak in the NH3-TPD test with a temperature > 450℃, preferably > 480℃.

[0050] The principle of the NH3-TPD test is to adsorb ammonia on the surface of the solid acid, and then desorb the ammonia by programmed temperature, and record the amount of ammonia during the adsorption process. In addition, the desorption peak temperature of the NH3-TPD test is an important indicator for evaluating the acidity of the catalyst. Specifically, the higher the NH3 desorption peak temperature, the stronger the acid center on the surface of the catalyst, indicating that the catalyst has increased acidity. This increase may be due to the presence of acid centers of different strengths on the surface of the catalyst, and the binding energy of acid centers of different strengths with NH3 is different. The desorption temperature range of chemisorbed NH3 can characterize the surface acid strength of the carrier. By analyzing the desorption peak temperature in the NH3-TPD spectrum, the acid strength of the catalyst can be qualitatively or quantitatively evaluated. Generally, weak acid centers are usually desorbed at < 200℃, medium-strong acid centers are desorbed at 200-400℃, and strong acid centers are desorbed at > 400℃. The type of acid center of the catalyst can be determined according to the above range.

[0051] The inventors have found that when the catalyst has at least one desorption peak in the NH3-TPD test with a temperature > 450℃, preferably > 480℃, the catalyst has better catalytic activity and selectivity.

[0052] In a specific embodiment, the catalyst comprises at least one strong acid center. The strong acid center is related to the acid center of the catalyst, specifically referring to an active center that can provide protons or accept electrons in the catalyst. The strong acid center of the solid acid is often the catalytically active center, which directly determines the catalytic efficiency and selectivity of the solid acid.

[0053] In addition, the catalyst can also comprise one or more weak acid centers. The present application does not make specific limitations on this, and the number of weak acid centers in the catalyst can be determined according to the number of < 200℃ peaks in the NH3-TPD test.

[0054] In a specific embodiment, in step 1), the temperature of the dehydration condensation reaction is 40-100℃, preferably 70-80℃, and the time is 0.2-2h, preferably 0.2-2h.

[0055] The temperature and time of the dehydration condensation directly affect the generation of the product, and controlling the temperature and time within the above range is beneficial to having a better dehydration condensation rate and yield.

[0056] In a specific embodiment, the molar ratio of formaldehyde to aniline is 0.2-0.6, preferably 0.3-0.55, and more preferably 0.4-0.5. On the one hand, within the above molar ratio range, formaldehyde can completely consume aniline, which can reduce production cost; on the other hand, by controlling the molar ratio within the above range, the reaction rate is moderate, which can effectively avoid the increase of side reactions caused by too fast reaction.

[0057] In a specific embodiment, in step 3), the temperature of the transposition rearrangement reaction is 80-120℃, preferably 100-120℃, and more preferably 120℃, and the time is 1-5h, preferably 2-4h, and more preferably 3h.

[0058] Within a certain range, the increase of temperature can increase the reaction rate, but too high temperature can reduce the selectivity of the reaction and produce more by-products. Based on the above consideration, the temperature of the transposition rearrangement reaction is limited within the above range. Among them, when the temperature is 120℃, the transposition rearrangement reaction has better reaction rate and selectivity.

[0059] Within a certain range, the extension of the reaction time can improve the conversion rate of the reactants, but too long time may cause unnecessary side reactions and reduce the yield of diphenylmethane series diamines and polyamines in the second product system. Based on the above consideration, the time of the transposition rearrangement reaction is limited within the above range. Among them, when the reaction time is 3h, it has better product yield.

[0060] In a specific embodiment, in step 2), the purification treatment comprises: performing oil-water two-phase separation treatment on the first product system comprising the aminal, and collecting the organic phase; and performing dehydration treatment on the organic phase to make the water content in the organic phase <50ppm.

[0061] The purification process comprises two steps, the first step is to remove the aqueous phase in the oil-water two-phase, and the second step is to remove the residual water in the organic phase.

[0062] The device for oil-water two-phase separation treatment is not limited in the present application, as long as it can perform oil-water two-phase separation, which can be an oil-water separator.

[0063] The present application can also use the conventional organic phase dehydration method in the art to perform water removal operation, for example, it can be one or more of molecular sieve dehydration, high polymer resin dehydration, and rectification, preferably molecular sieve dehydration. Molecular sieve is a silico-aluminate with porous structure, which has many uniform-sized pores and cavities inside, and can selectively adsorb molecules of specific size. The diameter of water molecules is small, which can be effectively adsorbed by molecular sieve, while other larger molecules cannot enter the pores of molecular sieve, thereby realizing the dehydration process.

[0064] Further, the molecular sieve can be one or both of 4A molecular sieve and 5A molecular sieve. The 5A molecular sieve is a calcium-potassium type silico-aluminate with a pore size of about 5A, and the 4A molecular sieve is an alkali metal silico-aluminate with a pore size of 4A. Both of the above two types of molecular sieves can well remove water molecules in the organic phase.

[0065] In a specific embodiment, in step 4), the refining treatment comprises sequentially performing evaporation treatment and stripping treatment on the second product system comprising the diamines and polyamines of the dimethylmethane series;

[0066] The evaporation treatment is performed at a pressure of 3-15 kPa and a temperature of 180-240°C, and the stripping treatment is performed at a pressure of 5-20 kPa and a temperature of 150-210°C.

[0067] Further, the evaporation treatment is preferably performed at a pressure of 5-9 kPa and a temperature of 205-215°C.

[0068] The pressure and temperature of the evaporation treatment and the pressure and temperature of the stripping treatment are limited in the above ranges, which can effectively remove light component substances such as aniline and water remaining in the second product system.

[0069] In a specific embodiment, the content of the tricyclic untransposed substance in the polyamines of the diphenylmethane series is <50 ppm. In the present application, the solid acid is used as the catalyst, which can improve the selectivity of the reaction and control the content of the tricyclic untransposed substance in the polyamines of the diphenylmethane series within the above level, so as to improve the quality of the product.

[0070] Hereinafter, the preparation method of the diamines and polyamines of the diphenylmethane series provided by the present application will be further described in combination with specific examples.

[0071] In the following examples, the experimental methods used can be conventional methods in the art unless otherwise specified.

[0072] In the following examples, all raw materials can be obtained by commercial purchase or conventional methods unless otherwise specified.

[0073] The sources of the main raw materials are as follows:

[0074] Aniline: produced by the aniline device in Ningbo Wanhua Industrial Park, industrial grade;

[0075] Formaldehyde: produced by the formaldehyde device in Ningbo Wanhua Industrial Park, industrial grade;

[0076] Hydrochloric acid: by-produced by the MDI device in Ningbo Wanhua Industrial Park, industrial grade.

[0077] The detection methods are as follows:

[0078] Method for determining each component in diamine and polyamine of diphenylmethane series (DAM): liquid chromatography, wherein the analysis instrument is Agilent 1200;

[0079] Method for testing solid acid amount: NH3-TPD method.

[0080] Example 1

[0081] The present embodiment provides a preparation method of diamine and polyamine of diphenylmethane series, comprising the following steps:

[0082] 1. Preparation of fatty sulfonic acid strong acid type cation exchange resin catalyst YL-1

[0083] 1) The polystyrene resin (PS-acyl-EDA) was added to a three-necked flask, and DMF was added for swelling for 12 hours, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), K2CO3 and tetrabutylammonium bromide (TBAB) were sequentially added, and the mixture was stirred to obtain a reaction mixture; wherein the molar ratio of AMPS, K2CO3, PS-acyl-EDA and TBAB was 5:1:1:1;

[0084] 2) The reaction mixture was refluxed at 120℃ in an oil bath for 20h, and after the reaction was completed, the reaction product was transferred to a sand core funnel, washed with 5% dilute hydrochloric acid solution for 20 times, then washed with distilled water until neutral, and finally washed with methanol and dried, and vacuum dried to constant weight to obtain the fatty sulfonic acid strong acid type cation exchange resin (YL-1).

[0085] According to NH3-TPD detection, the desorption peak temperature and acid amount of YL-1 are shown in Table 1 below.

[0086] 2. Preparation of diamine and polyamine of diphenylmethane series (DAM)

[0087] 1) Aniline material and formaldehyde material with a mass concentration of 37% were mixed and introduced into a reactor according to a molar ratio of 0.4:1 to perform a dehydration condensation reaction, the reaction temperature was 55℃, and the residence time was 60min, and an aldimine-containing stream was obtained after the reaction.

[0088] 2) The aldimine-containing stream obtained in step 1) was added to a first oil-water separator, and after standing until obvious water-oil separation occurred, the water layer and the oil layer were separated, and the lower oil layer obtained was the aldimine stream after the first dehydration, and after the first dehydration process, the aldimine stream was further subjected to water removal by passing through 5A molecular sieves at 60℃, and after the second dehydration, the water content in the aldimine stream was less than 30ppm;

[0089] 3) The dehydrated aminal stream obtained in step 2) is placed in a fixed bed reactor, the reactor is heated to 120°C, and a metathesis rearrangement reaction is carried out in the presence of YL-1, the reaction time is 90 min, and a stream containing diphenylmethane diamine and polyamines (DAM) is obtained;

[0090] 4) The stream containing diphenylmethane diamine and polyamines obtained in step 3) is placed in a stirred tank containing water, and a washing process is carried out under stirring to fully mix with water, and the washed stream is separated into layers in a second oil-water separator, and the separated oil phase is a crude DAM stream, which is evaporated at 10 kPa and 210°C, and stripped at 205 kPa and 190°C to remove light components such as aniline and water, and finally a refined DAM stream is obtained.

[0091] The contents of 4,4'-MDA, di-cyclic metathesis substances, tri-cyclic metathesis substances, and tri-cyclic non-metathesis substances in the refined DAM stream are shown in Table 1 below.

[0092] Example 2

[0093] This example provides a method for preparing diphenylmethane series diamines and polyamines, which is basically the same as Example 1, except that:

[0094] The catalyst used in the metathesis rearrangement reaction in step 3) is a cationic resin catalyst YL-2, which is obtained by modifying YL-1, and the modification method is as follows:

[0095] YL-1 is eluted with methanol until the water content of the effluent is less than 5%, and then the cationic resin catalyst after drying is immersed in a heteropoly acid impregnation solution for 12 hours, and then dried at 60°C to obtain the cationic resin catalyst YL-2.

[0096] The heteropoly acid impregnation solution is a 0.5wt% phosphotungstic acid aqueous solution.

[0097] The desorption peak temperature and acid amount of YL-2 are detected by NH3-TPD, and the contents of 4,4'-MDA, di-cyclic metathesis substances, tri-cyclic metathesis substances, and tri-cyclic non-metathesis substances in the refined DAM stream are detected by liquid chromatography, as shown in Table 1 below.

[0098] Example 3

[0099] This example provides a method for preparing diphenylmethane series diamines and polyamines, which is basically the same as Example 1, except that:

[0100] The catalyst used in the metathesis rearrangement reaction in step 3) is a Y-type molecular sieve.

[0101] The desorption peak maximum temperature and acid amount of the Y-type molecular sieve were detected by NH3-TPD, and the contents of 4,4'-MDA, bicyclic translocation substance, tricyclic translocation substance and tricyclic non-translocation substance in the refined DAM stream were detected by liquid chromatography, as shown in Table 1 below.

[0102] Example 4

[0103] The present example provides a preparation method of diphenylmethane series diamines and polyamines, which is basically the same as that of Example 1, except that:

[0104] The catalyst used in the translocation rearrangement reaction in step 3) is a modified Y-type molecular sieve, and the preparation method of the modified Y-type molecular sieve is as follows:

[0105] The carrier Y-type molecular sieve is immersed in a phosphotungstic acid solution with a concentration of 10 g / L, and the solid-liquid mass ratio is 1:5 to obtain a mixed solution; the mixed solution is sent into a rotating fluidized bed, the rotating speed is set to 3000 rpm, and the carrier material is treated at 150°C for 2h; after the treatment, the carrier material is taken out, and the excess solution is removed by centrifugation; finally, the above carrier is calcined at 200°C for 0.5h to obtain the modified Y-type molecular sieve.

[0106] The desorption peak maximum temperature and acid amount of the modified Y-type molecular sieve were detected by NH3-TPD, and the contents of 4,4'-MDA, bicyclic translocation substance, tricyclic translocation substance and tricyclic non-translocation substance in the refined DAM stream were detected by liquid chromatography, as shown in Table 1 below.

[0107] Example 5

[0108] The present example provides a preparation method of diphenylmethane series diamines and polyamines, which is basically the same as that of Example 1, except that:

[0109] The catalyst used in the translocation rearrangement reaction in step 3) is phosphotungstic acid.

[0110] The desorption peak maximum temperature and acid amount of the phosphotungstic acid were detected by NH3-TPD, and the contents of 4,4'-MDA, bicyclic translocation substance, tricyclic translocation substance and tricyclic non-translocation substance in the refined DAM stream were detected by liquid chromatography, as shown in Table 1 below.

[0111] Example 6

[0112] The present example provides a preparation method of diphenylmethane series diamines and polyamines, which is basically the same as that of Example 1, except that:

[0113] The catalyst used in the translocation rearrangement reaction in step 3) is HND-580 solid superacid.

[0114] The desorption peak temperature and acid amount of HND-580 were detected by NH3-TPD, and the contents of 4,4'-MDA, di-cyclic translocation substance, tri-cyclic translocation substance and tri-cyclic non-translocation substance in the refined DAM stream were detected by liquid chromatography, as shown in Table 1 below.

[0115] Comparative Example 1

[0116] The present comparative example provides a preparation method of diamines and polyamines in the diphenylmethane series, which is basically the same as that of Example 1, except that:

[0117] The catalyst used in the translocation rearrangement reaction in step 3) is 13X molecular sieve.

[0118] The desorption peak temperature and acid amount of 13X molecular sieve were detected by NH3-TPD, and the contents of 4,4'-MDA, di-cyclic translocation substance, tri-cyclic translocation substance and tri-cyclic non-translocation substance in the refined DAM stream were detected by liquid chromatography, as shown in Table 1 below.

[0119] Comparative Example 2

[0120] The present comparative example provides a preparation method of diamines and polyamines in the diphenylmethane series, which is basically the same as that of Example 1, except that:

[0121] The catalyst used in the translocation rearrangement reaction in step 3) is D152 weak acid cation exchange resin.

[0122] The desorption peak temperature and acid amount of D152 weak acid cation exchange resin were detected by NH3-TPD, and the contents of 4,4'-MDA, di-cyclic translocation substance, tri-cyclic translocation substance and tri-cyclic non-translocation substance in the refined DAM stream were detected by liquid chromatography, as shown in Table 1 below.

[0123] Comparative Example 3

[0124] The present comparative example provides a preparation method of diamines and polyamines in the diphenylmethane series, which is basically the same as that of Example 1, except that:

[0125] The catalyst used in the translocation rearrangement reaction in step 3) is 4A molecular sieve.

[0126] The desorption peak temperature and acid amount of 4A molecular sieve were detected by NH3-TPD, and the contents of 4,4'-MDA, di-cyclic translocation substance, tri-cyclic translocation substance and tri-cyclic non-translocation substance in the refined DAM stream were detected by liquid chromatography, as shown in Table 1 below.

[0127] Table 1

[0128]

[0129] The following conclusions can be drawn from Table 1:

[0130] As can be seen from Comparative Examples 1-6 and Comparative Examples 1-3, with the increase of the acid amount of the catalyst, the content of the tricyclic untransposed substance is significantly reduced, and the yield of 4,4'-MDA is also increased, wherein, compared with Comparative Examples 1-3, the acid amount of the catalyst in Examples 1-6 is greater than 1.3 mmol·g -1 , the content of the tricyclic untransposed substance is significantly reduced, and especially when the acid amount is greater than 1.4 mmol·g -1 (Examples 2 and 4), the content of the tricyclic untransposed substance is further reduced, and is not higher than 20 ppm, and the yield of 4,4'-MDA is not lower than 75%.

[0131] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of diamines and polyamines of the diphenylmethane series, characterized in that, The preparation method comprises the following steps: 1) subjecting formaldehyde and aniline to a dehydration condensation reaction to obtain a first product system comprising an acetal amine; 2) subjecting the first product system comprising the acetal amine to a purification treatment to obtain the acetal amine; 3) subjecting the acetal amine to a transposition rearrangement reaction under the action of a solid acid catalyst to obtain a second product system comprising diamines and polyamines of a diphenylmethane series; The solid acid catalyst has an acid amount of >1.4 mmol / g, and at least one desorption peak of the catalyst in an NH3-TPD test has a temperature of >450℃; 4) subjecting the second product system comprising diamines and polyamines of the diphenylmethane series to a refining treatment to obtain diamines and polyamines of the diphenylmethane series, wherein the content of tricyclic untransposed substances in the polyamines of the diphenylmethane series is <50 ppm.

2. The production method according to claim 1, characterized by, The solid acid catalyst comprises one or more of a cation exchange resin, a molecular sieve and a super acid.

3. The preparation method according to claim 2, characterized in that, The catalyst comprises at least one strong acid center.

4. The production method according to any one of claims 1 to 3, characterized by, In step 1), the dehydration condensation reaction has a temperature of 40-100℃ and a time of 0.2-2 h. And / or, the molar ratio of the aniline to the formaldehyde is (0.2-0.6):

1.

5. The method of any one of claims 1-3, wherein, In step 3), the transposition rearrangement reaction has a temperature of 80-120℃ and a time of 1-5 h.

6. The method of any one of claims 1-3, wherein, In step 2), the purification treatment comprises subjecting the first product system comprising the acetal amine to an oil-water two-phase separation treatment to collect an organic phase, and subjecting the organic phase to a dehydration treatment to make the water content in the organic phase <50 ppm.

7. The method of any one of claims 1-3, wherein, In step 4), the refining treatment comprises subjecting the second product system comprising diamines and polyamines of the dimethylmethane series to an evaporation treatment and a stripping treatment in sequence. The evaporation treatment has a pressure of 3-15 kPa and a temperature of 180-240℃, and the stripping treatment has a pressure of 5-20 kPa and a temperature of 150-210℃.

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