CN115232029B - Method for synthesizing biuret polyisocyanate, catalyst and preparation method thereof - Google Patents
Method for synthesizing biuret polyisocyanate, catalyst and preparation method thereof Download PDFInfo
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- CN115232029B CN115232029B CN202210786057.3A CN202210786057A CN115232029B CN 115232029 B CN115232029 B CN 115232029B CN 202210786057 A CN202210786057 A CN 202210786057A CN 115232029 B CN115232029 B CN 115232029B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C273/00—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
- C07C273/18—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups of substituted ureas
- C07C273/1872—Preparation of compounds comprising a -N-C(O)-N-C(O)-N- moiety
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/10—After treatment, characterised by the effect to be obtained
- B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
- B01J2229/183—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself in framework positions
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
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Abstract
The invention relates to a method for synthesizing biuret polyisocyanate, a catalyst and a preparation method thereof. Taking diisocyanate and water vapor as raw materials, and reacting in the presence of a catalyst to obtain biuret polyisocyanate, wherein the catalyst is a phosphorus modified molecular sieve, the phosphorus modified molecular sieve comprises a phosphorus-containing compound and a molecular sieve, the phosphorus-containing compound is connected with the molecular sieve through a P-O covalent bond, the molecular sieve comprises B acid and L acid, the pore size of the catalyst is 2-4nm, and the molar ratio of the B acid to the L acid of the catalyst is 1-5; the method comprises the step of adsorbing water vapor with the catalyst prior to the reaction. The synthetic method of the invention has high conversion rate of diisocyanate, no generation of insoluble polyurea, and high storage stability of the product.
Description
Technical Field
The invention relates to a method for synthesizing biuret polyisocyanate, a catalyst and a preparation method thereof.
Background
Currently biuret polyisocyanates are mostly synthesized by reacting water or water-generating reagents in situ with diisocyanate monomers. The above reaction is heterogeneous, and because water and diisocyanate monomer are difficult to be mutually dissolved, when water is added dropwise to the interface of two phases, the requirement of large excess of diisocyanate monomer cannot be satisfied. In addition, the heterogeneous reaction system can generate a large amount of insoluble white polyurea, so that the yield of the main reaction is affected, and the storage stability of the generated biuret polyisocyanate is poor. Finally, the water with low boiling point is added into the high-temperature reaction liquid in a dropwise manner, so that the water is instantaneously vaporized, the lost water vapor is liquefied at the wall of the reactor with lower temperature, and then the water vapor and the steam of the reaction liquid undergo side reaction, so that the yield of the main reaction is reduced.
Chinese patent CN101475680a discloses a method for synthesizing Hexamethylene Diisocyanate (HDI) biuret by spraying, which comprises adding hexamethylene diisocyanate into a reaction kettle, and spraying water in the form of mist droplets into the liquid surface of the reaction kettle under high pressure to react. This patent, while reducing the amount of HDI in the HDI biuret, does not address the conversion of HDI and the viscosity, chromaticity, stability, etc. of the product HDI biuret.
Chinese patent CN102382561B discloses a method of adding a crystalline hydrate to react with HDI at a reaction temperature controlled between 100 and 180 ℃, but the amount of water in the crystalline hydrate is relatively small, the amount of water is relatively large, the crystalline hydrate is not reusable, and the reaction rate is relatively slow.
Chinese patent CN103709076a discloses a method for continuously preparing biuret polyisocyanate, in which a mixed solution of diisocyanate and a catalyst, and steam are reacted in the form of aerosol, wherein the catalyst is a protonic acid such as phosphoric acid, etc., and the product prepared by the patent is transparent and not whitish, but the process inevitably generates polyurea precipitation, resulting in blockage of a reactor and water adding pipelines, and affecting continuous operation of a production device.
Disclosure of Invention
The object of the present invention is to provide a process for the synthesis of biuret polyisocyanates which allows high conversion of isocyanate monomers and which is free of insoluble polyurea formation in the reaction, and which is also low in product viscosity and colour and excellent in storage stability.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the method for synthesizing biuret polyisocyanate comprises the steps of taking diisocyanate and water vapor as raw materials, and reacting in the presence of a catalyst to obtain the biuret polyisocyanate, wherein the catalyst is a phosphorus modified molecular sieve, the phosphorus modified molecular sieve comprises a phosphorus-containing compound and a molecular sieve, the phosphorus-containing compound is connected with the molecular sieve through a P-O covalent bond, the molecular sieve comprises B acid and L acid, the pore size of the catalyst is 2-4nm, and the molar ratio of the B acid to the L acid of the catalyst is 1-5; the method comprises the step of adsorbing water vapor with the catalyst prior to the reaction.
In some embodiments, the molecular sieve is selected from the group consisting of one or more of an H beta molecular sieve, an HY molecular sieve, an HZSM-5 molecular sieve, an HZSM-11 molecular sieve, an H-type MCM-22 molecular sieve, and an H-type mordenite. Preferably, the molecular sieve is an HZSM-5 molecular sieve.
In some embodiments, the phosphorus-containing compound is selected from the group consisting of phosphoric acid, a phosphate salt, and a combination of one or more of alkyl phosphates.
Further, the phosphorus-containing compound is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, dibutyl phosphate and triethyl phosphate.
Further, the molar ratio of the phosphorus-containing compound to the molecular sieve is 1:2-1:10. Preferably, the molar ratio of the phosphorus-containing compound to the molecular sieve is 1:3-1:8.
Further, the mass ratio of the catalyst to the adsorbed water vapor is 3.5:1-10:1. Preferably, the mass ratio of the catalyst to the adsorbed water vapor is 4:1-7:1.
In some embodiments, the mass ratio of diisocyanate to catalyst adsorbed water vapor is from 35:1 to 100:1. Preferably, the mass ratio of the diisocyanate to the water vapor adsorbed by the catalyst is 40:1-80:1.
The invention adopts the specific phosphorus modified molecular sieve as the catalyst, and simultaneously absorbs the water vapor before the reaction, so that the catalyst can provide the reaction raw material water on one hand and serve as the acid catalyst on the other hand. The crystal cavity of the phosphorus modified molecular sieve catalyst has a strong polarization effect, and the catalyst has a proper specific surface area, can absorb proper amount of water vapor, and can uniformly release water in the subsequent reaction stage. The molecular sieve is modified by the phosphorus-containing compound to obtain the catalyst provided by the invention, which has proper molar ratio of B acid to L acid, so that the number of acid sites is proper, the phosphorus-containing compound can promote the reaction, and the phosphorus-containing compound is connected with the molecular sieve through a P-O bond, so that the phosphorus-containing group has a steric effect, and side reaction is reduced.
In some embodiments, the catalyst is prepared from a molecular sieve raw powder impregnated with a solution of the phosphorus-containing compound.
Further, the step of adsorbing the water vapor by the catalyst comprises the steps of purging the catalyst by adopting a mixed gas of the water vapor and inert gas, aging at normal temperature and drying.
Further, the diisocyanate is selected from one or more of hexamethylene diisocyanate, trimethyl-1, 6-hexamethylene diisocyanate, 1, 4-cyclohexane diisocyanate and xylylene diisocyanate. Preferably, the diisocyanate is selected from hexamethylene diisocyanate.
The method for synthesizing biuret polyisocyanate specifically comprises the following steps:
1) Soaking molecular sieve raw powder in the solution of the phosphorus-containing compound, drying, roasting and forming to obtain the catalyst;
2) Purging the catalyst by adopting mixed gas of water vapor and inert gas, aging at normal temperature, and drying;
3) A catalyst for adsorbing water vapor is added to the diisocyanate, and the reaction is performed under an inert gas atmosphere.
In some embodiments, the reaction is at a temperature of 60-180 ℃ for a time of 6-12 hours.
In some embodiments, the method further comprises: step 4) the resulting reaction mixture was purified in a wiped film evaporator.
The invention also provides the catalyst.
The invention also provides a preparation method of the catalyst, which comprises the steps of dipping the molecular sieve raw powder into the solution of the phosphorus-containing compound, drying, roasting and forming to obtain the catalyst.
In some embodiments, the phosphorus-containing compound solution has a mass concentration of 3% to 8%.
In some embodiments, the temperature of the impregnation is 20-100 ℃ for a period of 1-8 hours. Preferably, the temperature of the impregnation is 30-80 ℃ and the time is 3-5h.
In some embodiments, the drying is at a temperature of 30-120 ℃ for a time of 6-24 hours. Preferably, the drying temperature is 90-120 ℃ and the time is 10-18h.
In some embodiments, the firing is at a temperature of 450-850 ℃ for a period of 4-12 hours. Preferably, the roasting temperature is 500 ℃ and the time is 10 hours.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:
(1) The catalyst of the invention contains molecular sieve, which can absorb water and dewater, and no water or steam or in-situ water generating reagent is needed in the reaction process.
(2) The phosphorus modified molecular sieve catalyst prepared by the invention realizes the regulation of the surface acidity and the diffusion performance of the molecular sieve, has a proper molar ratio of B acid to L acid, can fully activate water molecules separated from the surface of the molecular sieve, promotes the efficient reaction of diisocyanate and water molecules, improves the reaction conversion rate, and effectively inhibits the formation of insoluble polyurea.
(3) The catalyst has a unique mesoporous structure, increases the reaction steric hindrance of phosphorus-containing groups in the catalyst, is unfavorable for further reaction of a catalytic product biuret polyisocyanate and raw water to generate high-polymer biuret, and further can obviously reduce the viscosity and chromaticity of the biuret polyisocyanate product and improve the storage stability of the biuret polyisocyanate product. The catalyst can be recycled for multiple times, and the catalytic activity is not obviously reduced.
Detailed Description
Preparation example 1
The preparation example provides a phosphorus modified molecular sieve catalyst:
(1) 100g of HZSM-5 molecular sieve raw powder is placed in a round bottom flask, 400g of phosphoric acid aqueous solution with mass concentration of 5% is added, stirring and soaking are carried out for 3 hours at 50 ℃, then filtration is carried out, and 300ml of deionized water is used for washing 3 times;
(2) Drying the product obtained in the step (1) in an oven at 120 ℃ for 12 hours;
(3) And (3) heating to 500 ℃ at a heating rate of 10 ℃/min, and calcining the dried product at the constant temperature of 500 ℃ for 10 hours to obtain the phosphorus modified HZSM-5 molecular sieve.
(4) And (5) extruding the strips at high pressure to form.
Preparation examples 2 to 6, comparative preparation examples 1 to 5
Preparation examples 2-6 and comparative preparation examples 1-3 also provided a modified molecular sieve catalyst, the corresponding preparation process was essentially the same as preparation example 1, except that: the molecular sieve raw powder is different in kind, modifier kind, soaking temperature, soaking time, drying temperature and drying time. The detailed process conditions are shown in Table 1, and the performance parameters of the prepared modified molecular sieve catalyst are shown in Table 1.
Table 1 catalyst preparation parameters and product performance parameters
Example 1
The present example provides a process for the preparation of biuret polyisocyanates:
(1) 30g of the catalyst in example 1 was purged with a mixture of water vapor and nitrogen (volume ratio: 4:1) for 2 hours, then aged at room temperature for 6 hours, and dried in a vacuum oven at 120℃for 12 hours to obtain a catalyst having 5g of water vapor adsorbed thereon.
(2) Under the nitrogen atmosphere, the nitrogen pressure is 1MPa, the catalyst after adsorbing the water vapor is added into HDI, the stirring is uniform, the stirring speed is 500rpm, the temperature is slowly increased to 145 ℃, and the reaction is carried out for 10 hours at 145 ℃.
(3) The reaction mixture was fed into a wiped film evaporator (vacuum: 120Pa; temperature: 145 ℃ C.) and the concentration of unreacted diisocyanate HDI in the reaction mixture was adjusted by the wiped film evaporator so that the concentration of HDI in the resultant reaction mixture was 5% by weight. The reaction mixture was again fed to a wiped film evaporator (vacuum: 120Pa, temperature: 135 ℃ C.) and separated to give the product HDI biuret.
Examples 2 to 10 and comparative examples 1 to 5
The preparation methods of examples 2 to 6 and comparative examples 1 to 5 are substantially the same as example 1, except that: the types of the catalysts are different, and the purging time in the step (1) is adjusted.
The preparation methods of examples 7-10 are substantially the same as in example 1, except that: the purge time in step (1) was adjusted so that the catalyst adsorbed water vapor in different amounts or the amount of HDI used and the reaction temperature were different, as shown in table 2.
TABLE 2 reaction conditions for examples 2-6, comparative examples 1-5
Note that: mass of catalyst adsorbed water vapor = mass of catalyst after adsorbed water vapor-mass of catalyst before adsorbed water vapor
Comparative example 6 (crystalline hydrate employed)
300g of HDI was added to the reaction vessel, the temperature was raised to 145℃and stirred, and 14g of CuSO was added 4 ·5H 2 O (Aba Ding Angu, purity 99.99%) and reacting for 10h to obtain a reaction mixture, and treating the reaction mixture according to step (3) of example (1) to obtain the product。
Examples 1-10, comparative examples 1-6 gave HDI biuret products with performance parameters as shown in Table 3, wherein the viscosity test was conducted using a rotary rheometer, the color test was conducted using a platinum cobalt color meter (EC 2000-Pt-Co) of Lovibond, the number average molecular weight was tested by GPC (gel permeation technique), the stable storage time was tested using gas chromatography, and the HDI content change of 1% or less was stable storage, and the catalyst was tested for the number of recycles by the same catalytic method as in the corresponding example.
TABLE 3 reaction results for examples 1-10, comparative examples 1-6
As can be seen from the comparison of tables 2, 3 and 4: the pore diameter of the phosphorus modified molecular sieve catalyst and the molar ratio of B acid/L acid are too large or too small, so that the release speed of water molecules is too high or too low, the release speed influences the local concentration of water molecules in a reaction system, and the conversion rate of HDI is too high or too low. When the conversion rate is too high, more high polymeric biuret is generated in the reaction, and the product viscosity is higher; when the conversion is too low, there is more HDI monomer in the reaction mixture, resulting in a significant increase in separation costs. Meanwhile, the proper mole ratio of B acid to L acid and the pore size can fully activate water molecules separated from the surface of the molecular sieve, promote the efficient reaction of diisocyanate and water molecules, effectively inhibit the formation of insoluble polyurea, and enable the prepared biuret-containing polyisocyanate to have the characteristics of good storage stability, low viscosity, low color number and low high content of polymeric biuret.
Example 7
This example provides a case of catalyst application.
The catalyst was used in the same manner as in example 1 and was recycled under the same conditions, and the results are shown in Table 5.
TABLE 5 results of catalyst set for PREPARATIVE EXAMPLE 1
The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be included in the scope of the present invention.
Claims (8)
1. A method for synthesizing biuret polyisocyanate, which takes diisocyanate and water vapor as raw materials and reacts in the presence of a catalyst, is characterized in that: the catalyst is a phosphorus modified molecular sieve, the phosphorus modified molecular sieve comprises a phosphorus-containing compound and a molecular sieve, the phosphorus-containing compound is connected with the molecular sieve through a P-O covalent bond, the molecular sieve comprises B acid and L acid, the pore size of the catalyst is 2-4nm, and the molar ratio of the B acid to the L acid of the catalyst is 1-5; the method comprises the step of adsorbing water vapor with the catalyst prior to the reaction; the molecular sieve is selected from one or a combination of a plurality of H beta molecular sieve, HY molecular sieve, HZSM-5 molecular sieve, HZSM-11 molecular sieve, H-type MCM-22 molecular sieve and H-type mordenite; the phosphorus-containing compound is selected from one or more of phosphoric acid, phosphate and alkyl phosphate; the catalyst is prepared by impregnating molecular sieve raw powder into the solution of the phosphorus-containing compound.
2. The method for synthesizing biuret polyisocyanates of claim 1, wherein: the phosphorus-containing compound is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, dibutyl phosphate and triethyl phosphate.
3. The method for synthesizing biuret polyisocyanates of claim 1, wherein: the mass ratio of the phosphorus-containing compound to the molecular sieve is 1:2-1:10; and/or the mass ratio of the catalyst to the adsorbed water vapor is 3.5:1-10:1; and/or the mass ratio of the diisocyanate to the water vapor adsorbed by the catalyst is 35:1-100:1.
4. The method for synthesizing biuret polyisocyanates of claim 1, wherein: the step of adsorbing the water vapor by the catalyst comprises the steps of purging the catalyst by adopting mixed gas of the water vapor and inert gas, aging at normal temperature and drying.
5. The method for synthesizing biuret polyisocyanates of claim 1, wherein: the diisocyanate is selected from one or more of hexamethylene diisocyanate, trimethyl-1, 6-hexamethylene diisocyanate, 1, 4-cyclohexane diisocyanate and xylylene diisocyanate.
6. The method for synthesizing biuret polyisocyanates of claim 1, wherein: the method specifically comprises the following steps:
1) Soaking molecular sieve raw powder in the solution of the phosphorus-containing compound, drying, roasting and forming to obtain the catalyst;
2) Purging the catalyst by adopting mixed gas of water vapor and inert gas, aging at normal temperature, and drying;
3) A catalyst for adsorbing water vapor is added to the diisocyanate, and the reaction is performed under an inert gas atmosphere.
7. The method for synthesizing biuret polyisocyanates of claim 6, wherein: the reaction temperature is 60-180 ℃ and the reaction time is 6-12h.
8. The method for synthesizing biuret polyisocyanates of claim 6, wherein: the method further comprises the steps of: step 4) the resulting reaction mixture was purified in a wiped film evaporator.
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| CN1243058C (en) * | 2003-12-09 | 2006-02-22 | 太原理工大学 | Polyaminoester /molecular sieve composite material and its preparation method |
| CN103724234B (en) * | 2014-01-03 | 2015-07-15 | 万华化学集团股份有限公司 | Method for preparing polyisocyanate containing biuret |
| CN106607081B (en) * | 2015-10-21 | 2019-05-21 | 中国石油化工股份有限公司 | A kind of method of organic phosphorus compound modified zsm-5 zeolite |
| CN107649173A (en) * | 2017-10-17 | 2018-02-02 | 上海应用技术大学 | A kind of molecular sieve catalysts of P Modification nanometer HZSM 5 and preparation method thereof |
| CN108439428B (en) * | 2018-03-30 | 2019-11-08 | 山东多友科技有限公司 | A kind of multi-stage porous ZSM-5 molecular sieve of P Modification and preparation method thereof |
| CN110833853B (en) * | 2018-08-17 | 2021-04-06 | 中国石油化工股份有限公司 | Modified Y-type molecular sieve and preparation method thereof |
| CN114471676B (en) * | 2020-10-28 | 2023-03-10 | 中国石油化工股份有限公司 | Cracking auxiliary agent |
| CN114073976B (en) * | 2020-08-10 | 2023-04-07 | 中国科学院大连化学物理研究所 | Modified ZSM-5 molecular sieve and preparation method and application thereof |
| CN113000026B (en) * | 2021-03-04 | 2023-04-14 | 上海绿强新材料有限公司 | Modified composite molecular sieve and preparation and application thereof |
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