Preparation method of diamine and polyamine of diphenylmethane series

Abstract

The invention provides a preparation method of diphenylmethane series diamine and polyamine. In the preparation method of diphenylmethane series diamine and polyamine, the solid acid catalyst with the acid content of more than 1.3 mmol / g is used as the catalyst for the aminal translocation rearrangement reaction, so that the selectivity of the solid acid catalyst in the aminal translocation rearrangement reaction can be obviously improved; the content of tricyclic non-transposition substances in diamine and polyamine products of diphenylmethane series is reduced, so that high-quality diphenylmethane diisocyanate can be obtained.

Description

Technical Field

[0001] The invention belongs to the field of organic chemical industry and relates to a method for preparing diphenylmethane series diamines and polyamines. Background Art

[0002] At present, the industrial production of diphenylmethane diisocyanate (MDI) includes three steps. The first step is the salt-forming reaction, in which aniline reacts with hydrochloric acid to produce aniline hydrochloride; the second step is the condensation transposition reaction, in which aniline hydrochloride reacts with formaldehyde to produce diphenylmethane series diamines and polyamines (DAM); the third step is the reaction to produce diphenylmethane diisocyanate. Among them, the diphenylmethane series diamines and polyamines of the second step product include 4,4'-diaminodiphenylmethane (MDA), the main component for preparing diphenylmethane diisocyanate. In the second step of condensation and transposition reaction, hydrochloric acid is usually selected as a 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, ensuring the quality of the reaction. However, the large amount of hydrochloric acid left after the transposition 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 used and reduce production costs. On the other hand, the transposition reactor uses expensive special materials, and adding a large number of equipment or significantly increasing the reaction temperature will inevitably increase production costs.

[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 methylene dianiline, 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 transpose the aminal, and the product contains a large amount of impurities such as tricyclic untransposed substances and dicyclic untransposed substances. These impurities enter the photochemical system and will 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 existing technology can effectively reduce the content of dicyclic untransposed substances in the transposition reaction product, but because the tricyclic transposition process is relatively complicated, the generation of tricyclic untransposed substances is difficult to control, and it is still impossible to effectively reduce the content of tricyclic untransposed substances.

[0004] Therefore, it is of great significance to develop a method for preparing diphenylmethane series diamines and polyamines with low cost, which can improve the selectivity of the metathesis reaction and reduce the content of the by-product tricyclic un-metamorphosed substances. Summary of the invention

[0005] In view of the defects existing in the prior art, the present invention provides a method for preparing diphenylmethane series diamines and polyamines, using a solid acid catalyst with an acid amount greater than 1.3 mmol / g as a catalyst for the aminal transposition rearrangement reaction, which 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 diamine and polyamine products, and thus facilitate the acquisition of high-quality diphenylmethane diisocyanate.

[0006] The present invention provides a method for preparing diamines and polyamines of a diphenylmethane series, the preparation method comprising the following steps:

[0007] 1) subjecting formaldehyde and aniline to a dehydration condensation reaction to obtain a first product system including aminal;

[0008] 2) purifying the first product system including aminal to obtain the aminal;

[0009] 3) Under the action of a solid acid catalyst, the aminal is subjected to a transposition rearrangement reaction to obtain a second product system including diamines and polyamines of a diphenylmethane series;

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

[0011] 4) Purifying the second product system including diphenylmethane series diamines and polyamines to obtain the diphenylmethane series diamines and polyamines.

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

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

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

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

[0016] In a preferred embodiment, in step 1), the temperature of the dehydration condensation reaction is 40-100° C., and the time is 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° C., and the time is 1-5 h.

[0019] In a preferred embodiment, in step 2), the purification treatment comprises: performing oil-water two-phase separation treatment on the first product system including aminal, and collecting the organic phase; and performing dehydration treatment on the organic phase to make the water content in the organic phase less than 50 ppm.

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

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

[0022] In a preferred embodiment, the content of tricyclic non-translocated substances in the diphenylmethane series polyamines is less than 50 ppm.

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

[0024] 1) The present invention uses a solid acid catalyst with an acid content greater than 1.3 mmol / g to carry out a transposition rearrangement reaction on aminal, which can significantly improve the selectivity of converting aminal into diamines and polyamines of the diphenylmethane series, reduce the content of untransposed substances, especially tricyclic untransposed substances, and thus facilitate the acquisition of high-quality diphenylmethane diisocyanate.

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

[0026] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The present invention provides a method for preparing diamines and polyamines of a diphenylmethane series, comprising the following steps:

[0028] 1) subjecting formaldehyde and aniline to a dehydration condensation reaction to obtain a first product system including aminal;

[0029] 2) purifying the first product system including aminal to obtain aminal;

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

[0031] Wherein, the acid amount of the solid acid catalyst is greater than 1.3 mmol / g;

[0032] 4) The second product system including diphenylmethane series diamines and polyamines is subjected to purification treatment 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 formula:

[0034]

[0035] Wherein, formaldehyde is a methylene donor, which can be selected from a 30% to 50% formaldehyde aqueous solution for reaction, and more preferably a 35% to 40% formaldehyde aqueous solution for reaction. After completing the reaction of step 1), the first product system includes water and some by-products in addition to aminal.

[0036] The presence of water can significantly affect the performance and life of solid acid catalysts. Specifically, water molecules may cause the expansion and contraction of the pore structure of solid acid catalysts, and may also react with acid sites to form hydroxides. The pore structure and acid sites are key factors affecting the activity of catalysts. Therefore, before using solid acid catalysts to catalyze the transposition rearrangement reaction, the first product system including aminal needs to be purified to remove the water therein and avoid the influence of water on the catalytic activity of the solid acid catalyst.

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

[0038]

[0039] Among them, the ideal rearrangement reaction obtains a dicyclic translocation substance and a tricyclic translocation substance as shown in the above reaction formula, among which the following isomers also belong to the dicyclic translocation substance:

[0040]

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

[0042]

[0043] Among them, the transposition substance refers to the amino group directly connected to the benzene ring after the aminal rearrangement, existing in the form of primary amine, and the non-transposition substance refers to the amino group still connected between the two benzene rings, existing in the form of secondary amine. For example, the bicyclic non-transposition substance includes , etc., tricyclic untranslocated substances include , When the selectivity of the rearrangement reaction is poor, there will be more untranslocated substances in the product. After entering the photochemical system, the secondary amine cannot react with phosgene to form isocyanate, resulting in more impurities in the product, affecting the product quality.

[0044] The present application uses a solid acid catalyst with an acid content of >1.3mmol / g to catalyze the transposition rearrangement reaction of acetalamine, which can significantly improve the selectivity of the rearrangement reaction and reduce the content of untransposed substances in the product, especially the content of tricyclic untransposed substances can be reduced to below 50ppm. 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 and reduce production costs. After the transposition rearrangement reaction, the solid acid can be recovered and reused by a simple solid-liquid separation method.

[0045] In step 4), the second product system including diphenylmethane series diamines and polyamines is subjected to a refining treatment, mainly to remove light impurities such as water and aniline, so as to obtain diphenylmethane series diamines and polyamines products with higher purity, and conventional refining treatment methods in the art can be used.

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

[0047] The acidity of a solid acid refers to the number or concentration of acid sites in a solid acid material, which directly affects the selectivity and activity of the catalyst. Generally speaking, the greater the acidity, the greater the density of the acid center, the greater the number of catalytically active sites, and the more favorable it is for increasing the rate of the catalytic reaction. Furthermore, when the acidity of a solid acid catalyst is greater than 1.4 mmol / g, the selectivity of the transposition rearrangement reaction is higher and the catalytic activity of the catalyst is better.

[0048] In the present invention, the method for testing the acid content of the solid acid catalyst can adopt conventional testing methods in the art, such as ammonia temperature-programmed desorption (NH3-TPD), titration, solid nuclear magnetic resonance, and pyridine infrared spectroscopy.

[0049] In a specific embodiment, the catalyst has at least one desorption peak with a temperature greater than 450°C, preferably greater than 480°C in an NH3-TPD test.

[0050] The principle of NH3-TPD test is to adsorb ammonia on the surface of solid acid, then desorb ammonia by program temperature increase, and record the amount of ammonia during adsorption. In addition, the desorption peak temperature of NH3-TPD test is an important indicator for evaluating the acidity of catalyst. Specifically, the high or low temperature of NH3 desorption peak directly reflects the strength of acid center on the catalyst surface. When the temperature of NH3 desorption peak increases, it indicates that the binding energy between acid center and NH3 on the catalyst surface is enhanced, that is, the acidity of catalyst increases. This increase may be due to the presence of acid centers of different strengths on the catalyst surface, and the binding energy between acid centers of different strengths and NH3 is different. The desorption temperature range of chemically adsorbed 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 speaking, weak acid centers usually desorb at less than 200℃, medium and strong acid centers desorb at 200~400℃, and strong acid centers desorb at more than 400℃. The acid center type of the catalyst can be judged according to the above range.

[0051] The inventors have found that when the temperature of at least one desorption peak of the catalyst in the NH3-TPD test is greater than 450°C, preferably greater than 480°C, the catalyst has better catalytic activity and selectivity.

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

[0053] In addition, the catalyst may also include one or more weak acid centers. The present invention does not specifically limit this, and the number of weak acid centers in the catalyst can be determined based on the number of peaks <200° C. in the NH3-TPD test.

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

[0055] Among them, the temperature and time of dehydration condensation will directly affect the formation of the product acetal amine. Controlling the temperature and time within the above range is conducive to having a better dehydration condensation rate and yield.

[0056] In a specific embodiment, the molar ratio of formaldehyde to aniline is 0.2 to 0.6, preferably 0.3 to 0.55, and more preferably 0.4 to 0.5. On the one hand, within the above molar ratio range, formaldehyde can completely consume aniline, which can reduce production costs; 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 a reaction.

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

[0058] Within a certain range, the temperature rise will increase the reaction rate, but too high a temperature will reduce the selectivity of the reaction and produce more by-products. Based on the above considerations, the temperature of the transposition rearrangement reaction is limited to the above range. Among them, when the temperature is 120°C, the transposition rearrangement reaction has a better reaction rate and selectivity.

[0059] Within a certain range, the reaction time can increase the conversion rate of the reactants, but if the reaction time is too long, unnecessary side reactions may occur, reducing the yield of diphenylmethane series diamines and polyamines in the second product system. Based on the above considerations, the time of the transposition rearrangement reaction is limited to the above range. Among them, when the reaction time is 3h, a better product yield is achieved.

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

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

[0062] The present invention does not limit the device for oil-water two-phase separation, as long as it can perform oil-water two-phase separation, and specifically it can be an oil-water separator.

[0063] The present invention can also use conventional organic phase dehydration methods in the art to perform water removal operations, such as molecular sieve dehydration, polymer resin dehydration, and distillation, and molecular sieve dehydration is preferred. Molecular sieve is a kind of aluminosilicate with a porous structure, which has many pores and holes of uniform size inside, and can selectively adsorb molecules of a specific size. Water molecules have a small diameter and can be effectively adsorbed by molecular sieves, while other larger molecules cannot enter the pores of molecular sieves, thereby achieving the dehydration process.

[0064] Furthermore, the molecular sieve may be one or both of 4A molecular sieve and 5A molecular sieve. 5A molecular sieve is a calcium potassium type aluminosilicate with a pore size of about 5Å, and 4A molecular sieve is an alkali metal aluminosilicate with a pore size of 4Å. The use of the above two molecular sieves with pore sizes can effectively remove water molecules in the organic phase.

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

[0066] The pressure of evaporation treatment is 3~15kPa and the temperature is 180~240℃; the pressure of stripping treatment is 5~20kPa and the temperature is 150~210℃.

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

[0068] Among them, limiting the pressure and temperature of the evaporation treatment and the pressure and temperature of the stripping treatment within the above range can effectively remove light components such as aniline and water remaining in the second product system.

[0069] In a specific embodiment, the content of the three-ring untranslocated substances in the diphenylmethane series polyamines is less than 50 ppm. In the present invention, the solid acid is used as a catalyst to improve the selectivity of the reaction and control the three-ring untranslocated substances in the diphenylmethane series polyamines within the above level to improve the quality of the product.

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

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

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

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

[0074] Aniline: Produced by Ningbo Aniline Plant in Ningbo Wanhua Industrial Park, industrial grade;

[0075] Formaldehyde: Produced by Ningbo Formaldehyde Plant in Ningbo Wanhua Industrial Park, industrial grade;

[0076] Hydrochloric acid: by-product of Ningbo MDI unit in Ningbo Wanhua Industrial Park, industrial grade.

[0077] The detection method is as follows:

[0078] Determination method of each component in diphenylmethane series diamines and polyamines (DAM): liquid chromatography, where the analytical instrument is Agilent 1200;

[0079] Solid acid acid content test method: NH3-TPD method.

[0080] Example 1

[0081] This embodiment provides a method for preparing diamines and polyamines of a diphenylmethane series, comprising the following steps:

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

[0083] 1) Add polystyrene resin (PS-acyl-EDA) into a three-necked flask, add DMF to swell for 12 hours, add 2-acrylamide-2-methylpropanesulfonic acid (AMPS), K2CO3 and tetrabutylammonium bromide (TBAB) in sequence, stir and mix to obtain a reaction mixture; wherein the molar ratio of AMPS, K2CO3, PS-acyl-EDA and TBAB is 5:1:1:1;

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

[0085] The maximum desorption peak temperature and acid content of YL-1 detected by NH3-TPD are shown in Table 1 below.

[0086] 2. Preparation of diamines and polyamines (DAM) of the diphenylmethane series

[0087] 1) Aniline material and formaldehyde material with a mass concentration of 37% are introduced into a reactor at a molar ratio of 0.4:1 and mixed for dehydration condensation reaction. The reaction temperature is 55° C. and the residence time is 60 min. After the reaction, a material stream containing aminal is obtained.

[0088] 2) adding the aminal stream obtained in the above step 1) to the first oil-water separator, standing until obvious water-oil separation occurs, separating the water layer and the oil layer, and obtaining the lower oil layer, which is the aminal stream after the first dehydration. After the first dehydration process is completed, the aminal stream is further dehydrated by passing through a 5A molecular sieve at 60° C., and the moisture content in the aminal stream after the second dehydration is less than 30 ppm;

[0089] 3) placing the aminal stream after secondary dehydration obtained in step 2) above in a fixed bed reactor, heating the reactor to 120° C., and performing a transposition rearrangement reaction in the presence of YL-1 for 90 min to obtain a stream containing diphenylmethanediamine and polyamine (DAM);

[0090] 4) The material stream containing diphenylmethanediamine and polyamines obtained in the above step 3) is placed in a stirring tank filled with water, and is fully mixed with water under stirring to perform a washing process. The washed material stream enters a second oil-water separator for stratification, and the separated oil phase is a crude DAM material stream. The crude DAM material stream 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 material stream is obtained.

[0091] The contents of 4,4'-MDA, dicyclic metastasis substances, tricyclic metastasis substances, and tricyclic non-transposition substances in the refined DAM stream are shown in Table 1 below after liquid chromatography detection.

[0092] Example 2

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

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

[0095] YL-1 was washed with methanol until the water content of the effluent was less than 5%, and then dried in a drying oven at 60°C for 3 hours. The dried cationic resin catalyst was immersed in the heteropolyacid impregnation solution and left to stand for 12 hours. The catalyst was taken out and dried at 60°C to obtain the cationic resin catalyst YL-2.

[0096] The heteropolyacid impregnation solution is an aqueous solution with a phosphotungstic acid concentration of 0.5 wt %.

[0097] The maximum desorption peak temperature and acid content of YL-2 detected by NH3-TPD are shown in Table 1 below; the contents of 4,4'-MDA, dicyclic metathesis material, tricyclic metathesis material, and tricyclic non-transposition material in the refined DAM stream detected by liquid chromatography are shown in Table 1 below.

[0098] Example 3

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

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

[0101] The maximum desorption peak temperature and acid content of the Y-type molecular sieve are shown in Table 1 after NH3-TPD detection; the contents of 4,4'-MDA, dicyclic metathesis material, tricyclic metathesis material, and tricyclic non-transposition material in the refined DAM stream are shown in Table 1 after liquid chromatography detection.

[0102] Example 4

[0103] This embodiment provides a method for preparing diphenylmethane series diamines and polyamines, which is basically the same as that of embodiment 1, except that:

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

[0105] Using Y-type molecular sieve as a carrier, the carrier is immersed in a phosphotungstic acid solution with a concentration of 10g / L and a solid-liquid mass ratio of 1:5 to obtain a mixed solution; the mixed solution is sent to a rotating fluidized bed, the speed is set to 3000rpm, and it 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-mentioned carrier is calcined at 200°C for 0.5h to obtain a modified Y-type molecular sieve.

[0106] The maximum desorption peak temperature and acid content of the modified Y-type molecular sieve are shown in Table 1 after NH3-TPD detection; the contents of 4,4'-MDA, dicyclic metathesis material, tricyclic metathesis material, and tricyclic non-transposition material in the refined DAM stream are shown in Table 1 after liquid chromatography detection.

[0107] Example 5

[0108] This embodiment provides a method for preparing diphenylmethane series diamines and polyamines, which is basically the same as that of embodiment 1, except that:

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

[0110] After NH3-TPD detection, the maximum desorption peak temperature and acid amount of phosphotungstic acid are shown in Table 1 below; after liquid chromatography detection, the contents of 4,4'-MDA, dicyclic metathesis material, tricyclic metathesis material, and tricyclic non-transposition material in the refined DAM stream are shown in Table 1 below.

[0111] Example 6

[0112] This embodiment provides a method for preparing diphenylmethane series diamines and polyamines, which is basically the same as that of embodiment 1, except that:

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

[0114] The maximum desorption peak temperature and acid content of HND-580 detected by NH3-TPD are shown in Table 1 below; the contents of 4,4'-MDA, dicyclic metathesis material, tricyclic metathesis material, and tricyclic non-transposition material in the refined DAM stream detected by liquid chromatography are shown in Table 1 below.

[0115] Comparative Example 1

[0116] This comparative example provides a method for preparing diphenylmethane series diamines and polyamines, which is basically the same as Example 1, except that:

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

[0118] The maximum desorption peak temperature and acid content of 13X molecular sieves detected by NH3-TPD are shown in Table 1 below; the contents of 4,4'-MDA, dicyclic metathesis material, tricyclic metathesis material, and tricyclic non-transposition material in the refined DAM stream detected by liquid chromatography are shown in Table 1 below.

[0119] Comparative Example 2

[0120] This comparative example provides a method for preparing diphenylmethane series diamines and polyamines, which is basically the same as Example 1, except that:

[0121] The catalyst used in the transposition rearrangement reaction in step 3) is D152 weakly acidic cation exchange resin.

[0122] After NH3-TPD detection, the maximum desorption peak temperature and acid content of D152 weakly acidic cation exchange resin are shown in Table 1 below; after liquid chromatography detection, the contents of 4,4'-MDA, dicyclic metathesis material, tricyclic metathesis material, and tricyclic non-transposition material in the refined DAM stream are shown in Table 1 below.

[0123] Comparative Example 3

[0124] This comparative example provides a method for preparing diphenylmethane series diamines and polyamines, which is basically the same as Example 1, except that:

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

[0126] The maximum desorption peak temperature and acid content of 4A molecular sieve detected by NH3-TPD are shown in Table 1 below; the contents of 4,4'-MDA, dicyclic metathesis material, tricyclic metathesis material, and tricyclic non-transposition material in the refined DAM stream detected by liquid chromatography are shown in Table 1 below.

[0127] Table 1

[0128]

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

[0130] By comparing Examples 1 to 6 and Comparative Examples 1 to 3, it can be seen that as the amount of catalyst acid increases, the content of tricyclic untranslocated substances is significantly reduced, and the yield of 4,4'-MDA also increases accordingly. Compared with Comparative Examples 1 to 3, the amount of acid in the catalyst of Examples 1 to 6 is greater than 1.3 mmol·g -1 The content of the tricyclic untranslocated substances decreased significantly, especially when the acid content was greater than 1.4 mmol·g -1 (Examples 2 and 4), the content of the tricyclic untranslocated substance further decreased to no more than 20 ppm, and the yield of 4,4'-MDA was no less than 75%.

[0131] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing diamines and polyamines of a 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 including aminal; 2) purifying the first product system including aminal to obtain the aminal; 3) Under the action of a solid acid catalyst, the aminal is subjected to a transposition rearrangement reaction to obtain a second product system including diamines and polyamines of a diphenylmethane series; The acid amount of the solid acid catalyst is greater than 1.3 mmol / g; 4) Purifying the second product system including diphenylmethane series diamines and polyamines to obtain the diphenylmethane series diamines and polyamines.

2. The preparation method according to claim 1, characterized in that: The solid acid catalyst includes one or more of a cation exchange resin, a molecular sieve, and a superacid.

3. The preparation method according to claim 1 or 2, characterized in that: The acid amount of the solid acid catalyst is greater than 1.4 mmol / g.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The catalyst has at least one desorption peak with a temperature greater than 450° C., preferably greater than 480° C. in an NH 3 -TPD test.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The catalyst includes at least one strongly acidic center.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In step 1), the temperature of the dehydration condensation reaction is 40-100°C and the time is 0.2-2h; And / or, the molar ratio of the aniline to the formaldehyde is (0.2-0.6):

1.

7. The preparation method according to any one of claims 1 to 6, characterized in that: In step 3), the temperature of the transposition rearrangement reaction is 80-120° C. and the time is 1-5 h.

8. The preparation method according to any one of claims 1 to 7, characterized in that: In step 2), the purification treatment includes: performing oil-water two-phase separation treatment on the first product system including aminal, and collecting the organic phase; and performing dehydration treatment on the organic phase to make the water content in the organic phase less than 50 ppm.

9. The preparation method according to any one of claims 1 to 8, characterized in that: In step 4), the refining treatment includes sequentially performing evaporation treatment and stripping treatment on the second product system including diamines and polyamines of the dimethylmethane series; The pressure of the evaporation treatment is 3-15 kPa, and the temperature is 180-240°C; the pressure of the stripping treatment is 5-20 kPa, and the temperature is 150-210°C.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The content of tricyclic untransposed substances in diphenylmethane series polyamines is less than 50ppm.

Images