A zinc-containing catalyst, a preparation method and application thereof

Abstract

The present disclosure provides a zinc-containing catalyst and a preparation method and application thereof, and belongs to the technical field of catalysts. The present disclosure catalyzes the polymerization reaction of an amino compound, an aldehyde-based compound and a zinc salt by a catalyst to obtain a zinc-containing catalyst. The specific surface area of the obtained zinc-containing catalyst is large and has a nanometer-level pore channel, and the zinc-containing catalyst is used for catalytic synthesis of polycarbonate and has high catalytic efficiency.

Description

Technical Field

[0001] This disclosure relates to the field of catalyst technology, specifically to a zinc-containing catalyst, its preparation method, and its application. Background Technology

[0002] With the rapid development of modern industry, humans emit large amounts of carbon dioxide into the atmosphere every year, causing the atmospheric carbon dioxide content to increase annually. This massive emission of carbon dioxide has led to a severe greenhouse effect, and controlling and reducing carbon dioxide emissions has become a global consensus. Carbon dioxide is also an important carbon resource in nature, and its development and comprehensive utilization have always been a key research direction in C1 chemistry. Currently, carbon dioxide is mainly used in carbonated beverages, fire extinguishing agents, refrigerants, and supercritical extraction solvents, but the demand is small, the market potential is limited, and the application scope is restricted, hindering large-scale industrial application.

[0003] With the increasing scarcity of global carbon resources, especially oil resources, and heightened concerns about the greenhouse effect caused by carbon dioxide, countries worldwide have intensified their research and development efforts in the comprehensive utilization of carbon dioxide in the chemical industry. One promising approach is to copolymerize carbon dioxide with epoxy compounds to prepare aliphatic polycarbonates. The most commonly used epoxy monomers are propylene oxide and cyclohexane oxide, and the copolymerization products are polypropylene carbonate and polycyclohexene carbonate, respectively. However, carbon dioxide is chemically inert and difficult to participate in copolymerization reactions. Therefore, how to prepare high-performance aliphatic polycarbonates under relatively mild conditions is a key challenge in this research. The main solution lies in developing and applying catalysts with high catalytic efficiency and selectivity.

[0004] Researchers have developed various catalytic systems for polycarbonate preparation, including diethylzinc, zinc carboxylate, rare earth, Schiff alkali metal complexes, and dimetallic cyanide (DMC) systems. However, most of these catalysts exhibit low catalytic activity, require long reaction times and high polymerization pressures, necessitate organic solvents, and generate cyclic small-molecule carbonate byproducts. Furthermore, they suffer from low catalytic efficiency and difficulties in separating the product from the catalyst. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a zinc-containing catalyst, its preparation method and application. The zinc-containing catalyst has a large specific surface area and nanoscale pores, and is used for the catalytic synthesis of polycarbonate with high catalytic efficiency.

[0006] To achieve the above objectives, the technical solution adopted in this disclosure is as follows: a method for preparing a zinc-containing catalyst, comprising the following steps:

[0007] An amino compound, an aldehyde compound, a zinc salt, a catalyst, and a solvent are mixed and subjected to a polymerization reaction to obtain a zinc-containing catalyst.

[0008] The structural formula of the amino compound is shown in Formula 1, and the structural formula of the aldehyde compound is shown in Formula 2.

[0009]

[0010] The zinc salt is at least one of zinc chloride, zinc acetate, diethyl zinc, zinc glutarate, zinc cobalt cyanate, and N,N'-disalicylaldehyde ethylenediamine zinc;

[0011] The catalyst is acetic acid and p-toluenesulfonic acid.

[0012] In one embodiment, the molar ratio of the amino compound, the aldehyde compound, and the zinc salt is amino compound: aldehyde compound: zinc salt = (1:1:1) - (1:4:4).

[0013] In one embodiment, the polymerization reaction is carried out at a temperature of 60–150°C; and / or the polymerization reaction is carried out for a time of 10–48 h.

[0014] In one embodiment, the molar ratio of acetic acid to p-toluenesulfonic acid is (1:1) to (1:2).

[0015] In one embodiment, the amount of the solvent tetrahydrofuran is 40-120 mL.

[0016] In one embodiment, the mass of the catalyst and the total molar ratio of the amino compound to the aldehyde compound is 0.1 g:(1-2 mmol).

[0017] In one embodiment, after the polymerization reaction is completed, the resulting product is sequentially filtered, washed, Soxhlet extracted and dried to obtain a zinc-containing catalyst.

[0018] In one embodiment, the solvent is at least one selected from chloroform, ether, benzene, methyl acetate, tetrahydrofuran, acetone, methanol, petroleum, chlorophenol, dichloroethylene, and carbon tetrachloride.

[0019] On the other hand, a zinc-containing catalyst is provided, which is prepared by the above-described method for preparing zinc-containing catalysts.

[0020] On the other hand, the application of the zinc-containing catalyst in the catalytic synthesis of polycarbonate is provided.

[0021] In one embodiment, the application includes the following steps: copolymerizing cyclohexane oxide, ethylene oxide, and carbon dioxide in the presence of a zinc-containing catalyst.

[0022] In one embodiment, the amount of the zinc-containing catalyst is 10-20 mg / mL; and / or, the molar ratio of cyclohexane oxide to ethylene oxide is 5:1 to 1:5; and / or, the carbon dioxide pressure is 1-5 MPa; and / or, the copolymerization reaction temperature is 60-120°C; and / or, the copolymerization reaction time is 5-12 h.

[0023] Compared with the prior art, the beneficial effects of this disclosure are as follows: This disclosure uses a catalyst to catalyze the polymerization reaction of amino compounds, aldehyde compounds and zinc salts to obtain a zinc-containing catalyst. The obtained zinc-containing catalyst has a large specific surface area and nanoscale pores, and is used to catalyze the synthesis of polycarbonate with high catalytic efficiency. Detailed Implementation

[0024] The advantages and features of this disclosure, as well as the methods for achieving said advantages and features, will be more readily understood by referring to the following detailed description of embodiments. However, this disclosure may be implemented in various other forms and should not be construed as limited to the embodiments set forth herein. The embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0025] The terminology used in this specification is intended to describe certain embodiments only and should in no way limit this disclosure. Unless expressly used otherwise, singular expressions include the meaning of plural expressions.

[0026] Unless otherwise defined, all terms used in this disclosure (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Any term defined in a comprehensive dictionary shall be interpreted as having the same meaning in the context of the relevant field.

[0027] The zinc-containing catalysts according to this disclosure, their preparation methods, and their applications will be described in detail below.

[0028] This disclosure provides a method for preparing a zinc-containing catalyst, comprising the following steps:

[0029] An amino compound, an aldehyde compound, a zinc salt, a catalyst, and a solvent are mixed and subjected to a polymerization reaction to obtain a zinc-containing catalyst.

[0030] The structural formula of the amino compound is shown in Formula 1, and the structural formula of the aldehyde compound is shown in Formula 2.

[0031] CAS: 106-50-3;

[0032] CAS: 2243590-42-1, purchased from Alpha Chemicals Ltd.;

[0033] The zinc salt is at least one of zinc chloride, zinc acetate, diethyl zinc, zinc glutarate, zinc cobalt cyanate, and N,N'-disalicylaldehyde ethylenediamine zinc;

[0034] The catalyst is acetic acid and p-toluenesulfonic acid.

[0035] In this disclosure, acetic acid and p-toluenesulfonic acid are used as catalysts to catalyze the polymerization reaction of amino compounds, aldehyde compounds, and zinc salts, resulting in a zinc-containing catalyst with a large specific surface area and nanopores. The zinc-containing catalyst uses benzene rings as structural units, and the amino compounds, aldehyde compounds, and zinc salts are interconnected by covalent bonds, giving the zinc-containing catalyst a rigid structure. This structure effectively supports the nanopore structure of the zinc-containing catalyst, increasing its specific surface area. This, in turn, increases the number of exposed catalytic sites and the utilization efficiency of these sites, preventing pore collapse during use and thus improving the catalytic performance of the zinc-containing catalyst.

[0036] Specifically, zinc serves as the active center of zinc-containing catalysts. To obtain zinc-containing catalysts with high catalytic performance, the content of zinc salts needs to be controlled during the preparation process. If the content of zinc salts is too high, the specific surface area of ​​the zinc-containing catalyst decreases, leading to a sharp reduction in its catalytic performance. If the content of zinc salts is too low, the thermal and chemical stability of the zinc-containing catalyst is low. Therefore, this disclosure selects the molar ratio of amino compound, aldehyde compound, and zinc salt as amino compound: aldehyde compound: zinc salt = (1:1:1)-(1:4:4). This can effectively increase the number of functional groups and nanopores in the zinc-containing catalyst, thereby improving its catalytic performance and stability. Preferably, the molar ratio of amino compound, aldehyde compound, and zinc salt is amino compound: aldehyde compound: zinc salt = (1:1:1)-(1:3:3). More preferably, the molar ratio of amino compound, aldehyde compound, and zinc salt is amino compound: aldehyde compound: zinc salt = (1:1:1)-(1:2:2). Through optimization, the zinc-containing catalyst prepared within the above-mentioned molar ratio range can effectively ensure that the catalytic performance and stability are maintained within a suitable range. Furthermore, selecting appropriate reaction temperatures and times can further enhance the catalytic performance and stability of the product.

[0037] Specifically, the polymerization temperature is 60–150°C; and / or the polymerization time is 10–48 h.

[0038] In this disclosure, the polymerization temperature can be 60℃, 70℃, 80, 90℃, 100℃, 110℃, 120℃, or 130℃; or it can be a range of any two of the above values; preferably 110-125℃, more preferably 120℃.

[0039] The polymerization reaction time can be 10h, 15h, 20h, 25h, 30h, 35h, 40h, 44h, or 48h; or it can be a range of any two of the above values; preferably 30-45h, more preferably 40h.

[0040] Both the temperature and time of the polymerization reaction affect the catalytic performance and stability of zinc-containing catalysts. Excessively high temperatures or prolonged reaction times can cause the polymerization system to boil, leading to decreased catalytic activity of acetic acid and p-toluenesulfonic acid, and loss of zinc salt activity, thus reducing the thermal stability and catalytic performance of the zinc-containing catalyst. Conversely, excessively low temperatures or short reaction times reduce the degree of polymerization of the zinc-containing catalyst, resulting in decreased mechanical strength and specific surface area, thereby reducing its catalytic performance and chemical stability. Those skilled in the art can adjust the polymerization temperature (60–150°C) and reaction time (10–48 h) to obtain zinc-containing catalysts with improved catalytic performance and stability.

[0041] Specifically, the molar ratio of acetic acid to p-toluenesulfonic acid is (1:1)-(1:2).

[0042] If the molar ratio of acetic acid to p-toluenesulfonic acid is too small or too large, the catalytic effect of acetic acid and p-toluenesulfonic acid will be reduced, thereby affecting the polymerization reaction of amino compounds, aldehyde compounds and zinc salts; and consequently leading to a decrease in the performance of zinc-containing catalysts.

[0043] Specifically, the mass of the catalyst and the total molar ratio of the amino compound to the aldehyde compound are 0.1 g:(1-2 mmol).

[0044] Specifically, in this disclosure, in order to further improve the purity of the zinc-containing catalyst, after the polymerization reaction is completed, the obtained product needs to be filtered, washed, Soxhlet extracted and dried in sequence.

[0045] This disclosure does not impose any special limitations on the specific operation method of the filtering described herein; any filtering method well known to those skilled in the art can be used.

[0046] This disclosure does not specify any particular washing solution; any washing solution well known in the art, such as deionized water, ethanol, and tetrahydrofuran, can be used.

[0047] This disclosure does not specifically limit the solvent used for Soxhlet extraction, and solvents well known in the art for Soxhlet extraction are used. This disclosure preferably uses dichloromethane, tetrahydrofuran, and petroleum ether for Soxhlet extraction. The specific steps are as follows: the washed product is sequentially subjected to Soxhlet extraction with dichloromethane, tetrahydrofuran, and petroleum ether.

[0048] This disclosure does not impose any special limitation on the Soxhlet extraction time. Those skilled in the art can choose an appropriate time according to actual needs. This disclosure selects a Soxhlet extraction time of 48-72 hours / time, preferably 60-70 hours / time, and more preferably 70 hours / time.

[0049] This disclosure does not specify a particular drying method; any filtration method well-known to those skilled in the art can be used. The preferred drying method in this disclosure is vacuum drying.

[0050] This disclosure does not specify the drying temperature and time, and those skilled in the art can select a suitable temperature and time according to actual needs. This disclosure selects a drying temperature of 50-100℃ and a drying time of 18-24h; preferably, the drying temperature is 75-95℃ and the drying time is 21-23h; more preferably, the drying temperature is 80℃ and the drying time is 22h.

[0051] Specifically, in this disclosure, the solvent is at least one selected from chloroform, ether, benzene, methyl acetate, tetrahydrofuran, acetone, methanol, petroleum, chlorophenol, dichloroethylene, and carbon tetrachloride; preferably, the solvent is tetrahydrofuran.

[0052] This disclosure also discloses a zinc-containing catalyst, which is prepared by the above-described method for preparing zinc-containing catalysts.

[0053] This disclosure also discloses the application of the zinc-containing catalyst in the catalytic synthesis of polycarbonate.

[0054] Specifically, the application includes the following steps: copolymerizing cyclohexane oxide, ethylene oxide, and carbon dioxide in the presence of a zinc-containing catalyst.

[0055] Specifically, the amount of zinc-containing catalyst used is 10-20 mg / mL; and / or, the molar ratio of cyclohexane oxide to ethylene oxide is 5:1 to 1:5; and / or, the carbon dioxide pressure is 1-5 MPa; and / or, the copolymerization reaction temperature is 60-120 °C; and / or, the copolymerization reaction time is 5-12 h.

[0056] The CAS number for cyclohexane oxide is 286-20-4.

[0057] This disclosure can be further demonstrated by the following examples, which should not be considered limiting. Unless otherwise stated, all materials used in any of the embodiments and comparative examples herein are commercially available.

[0058] Example 1

[0059] The preparation method of the zinc-containing catalyst in this embodiment includes the following steps:

[0060] 0.6 g of acetic acid and 1.72 g of p-toluenesulfonic acid were added to a round-bottom flask. After evacuating the flask, nitrogen gas was introduced, followed by the injection of 50 mL of tetrahydrofuran. Then, an aldehyde compound, an amino compound, and zinc chloride were added to the round-bottom flask, with a molar ratio of amino compound: aldehyde compound: zinc chloride of 1:1:1. The mixture was heated to 120 °C for 48 hours. After the reaction was completed, the mixture was cooled to room temperature and then filtered. The crude product obtained by filtration was washed with deionized water, and the washed product was successively subjected to Soxhlet extraction with dichloromethane, tetrahydrofuran, and petroleum ether. The Soxhlet extract was dried under vacuum at 100 °C for 20 hours to obtain a zinc-containing catalyst.

[0061] Example 2

[0062] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that zinc acetate is used instead of zinc chloride.

[0063] Example 3

[0064] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that diethylzinc is used instead of zinc chloride.

[0065] Example 4

[0066] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that zinc glutarate is used instead of zinc chloride.

[0067] Example 5

[0068] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that zinc chloride is replaced with zinc N,N'-disalicylaldehyde ethylenediaminezinc.

[0069] Example 6

[0070] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the molar ratio of amino compound, aldehyde compound and zinc chloride is amino compound: aldehyde compound: zinc chloride = 1:1:2.

[0071] Example 7

[0072] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the molar ratio of amino compound, aldehyde compound and zinc chloride is amino compound: aldehyde compound: zinc chloride = 1:2:2.

[0073] Example 8

[0074] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the molar ratio of amino compound, aldehyde compound and zinc chloride is amino compound: aldehyde compound: zinc chloride = 1:2:3.

[0075] Example 9

[0076] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the molar ratio of amino compound, aldehyde compound and zinc chloride is amino compound: aldehyde compound: zinc chloride = 1:3:3.

[0077] Example 10

[0078] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the molar ratio of amino compound, aldehyde compound and zinc chloride is amino compound: aldehyde compound: zinc chloride = 1:3:4.

[0079] Example 11

[0080] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the molar ratio of amino compound, aldehyde compound and zinc chloride is amino compound: aldehyde compound: zinc chloride = 1:4:3.

[0081] Example 12

[0082] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the molar ratio of amino compound, aldehyde compound and zinc chloride is amino compound: aldehyde compound: zinc chloride = 1:4:4.

[0083] Example 13

[0084] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the polymerization reaction temperature is 60°C.

[0085] Example 14

[0086] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the polymerization reaction temperature is 70°C.

[0087] Example 15

[0088] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the polymerization reaction temperature is 80°C.

[0089] Example 16

[0090] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the polymerization reaction temperature is 90°C.

[0091] Example 17

[0092] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the polymerization reaction temperature is 100°C.

[0093] Example 18

[0094] The only difference between the preparation method of the zinc-containing catalyst in this embodiment and that in Example 1 is that the polymerization reaction temperature is 130°C.

[0095] Example 19

[0096] The catalytic performance, thermal stability, and chemical stability of the zinc-containing catalysts obtained in each example and comparative example were tested. The test methods are as follows:

[0097] Specific surface area: Nova 600BET specific surface area and pore size analyzer.

[0098] Catalytic performance: In the presence of a zinc-containing catalyst, cyclohexane oxide, ethylene oxide and carbon dioxide are copolymerized; the parameters of the copolymerization reaction are shown in Table 1.

[0099] Thermal stability: The thermal stability of the catalyst was tested using a DZ-TGA105 high-temperature thermogravimetric analyzer. Tensile strength: Tested using a YP-LL-05 dual-column touch-sensitive tensile and compressive strength testing machine. The test results are shown in Table 1.

[0100] Table 1

[0101]

[0102] Table 1 shows the catalytic performance, thermal stability, and tensile strength of the zinc-containing catalyst disclosed in this invention.

[0103] As can be seen from the comparison of Examples 1-5, the zinc salt is zinc chloride, and the resulting zinc-containing catalyst has higher catalytic efficiency.

[0104] Comparing Examples 1 and 6-12, it can be seen that when the molar ratio of amino compound, aldehyde compound, and zinc salt is amino compound: aldehyde compound: zinc salt = (1:2:2)-(1:4:4), the obtained zinc-containing catalyst has better catalytic performance and stability; when the molar ratio of amino compound, aldehyde compound, and zinc salt is amino compound: aldehyde compound: zinc salt = (1:3:3)-(1:4:4), the obtained zinc-containing catalyst has excellent catalytic performance and stability.

[0105] Comparing Examples 1 and 13-18, it can be seen that a polymerization temperature of 110-130℃ is beneficial to improving the catalytic performance and stability of the zinc-containing catalyst; the polymerization temperature of 120℃ is the optimal temperature for the catalytic performance and stability of the zinc-containing catalyst.

[0106] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of this disclosure and not to limit the scope of protection of this disclosure. Although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this disclosure without departing from the substance and scope of the technical solutions of this disclosure.

Claims

1. A method for preparing a zinc-containing catalyst for the catalytic synthesis of polycarbonate, characterized in that, The process includes the following steps: mixing an amino compound, an aldehyde compound, a zinc salt, a catalyst, and a solvent, and carrying out a polymerization reaction to obtain a zinc-containing catalyst; The structural formula of the amino compound is shown in Formula 1, and the structural formula of the aldehyde compound is shown in Formula 2. Formula 1, Formula 2; The zinc salt is at least one of zinc chloride, zinc acetate, diethyl zinc, zinc glutarate, zinc cobalt cyanate, and N,N'-disalicylaldehyde ethylenediamine zinc; The catalyst is acetic acid and p-toluenesulfonic acid; The polymerization reaction is carried out at a temperature of 110-130°C for 10-48 hours. The molar ratio of the amino compound, aldehyde compound, and zinc salt is amino compound: aldehyde compound: zinc salt = (1:2:2) - (1:4:4). The molar ratio of acetic acid to p-toluenesulfonic acid is (1:1) to (1:2).

2. The preparation method according to claim 1, characterized in that, The mass of the catalyst and the total molar ratio of the amino compound to the aldehyde compound are 0.1 g: (2-5 mmol).

3. The preparation method according to claim 1, characterized in that, After the polymerization reaction was completed, the resulting product was sequentially filtered, washed, Soxhlet extracted and dried to obtain a zinc-containing catalyst.

4. The preparation method according to claim 1, characterized in that, The solvent is at least one of chloroform, ether, benzene, methyl acetate, tetrahydrofuran, acetone, methanol, petroleum, chlorophenol, dichloroethylene, and carbon tetrachloride.

5. A zinc-containing catalyst, characterized in that, The zinc-containing catalyst is prepared by the method described in any one of claims 1-4.

6. The application of the zinc-containing catalyst as described in claim 5 in the catalytic synthesis of polycarbonate.

7. The application as described in claim 6, characterized in that, The application includes the following steps: copolymerizing cyclohexane oxide, ethylene oxide, and carbon dioxide in the presence of a zinc-containing catalyst.

8. The application as described in claim 7, characterized in that, The amount of zinc-containing catalyst used is 10-20 mg / mL; and / or, the molar ratio of cyclohexane oxide to ethylene oxide is 5:1 to 1:5; and / or, the carbon dioxide pressure is 1-5 MPa; and / or, the copolymerization reaction temperature is 60-120℃; and / or, the copolymerization reaction time is 5-12 h.

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