Bismuth-based catalyst as well as preparation method and application thereof

Abstract

The invention discloses a bismuth-based catalyst and a preparation method and application thereof, the catalyst comprises a carrier and metal bismuth oxide and iron oxide loaded on the carrier, the carrier is petal-shaped mesoporous silica, and the metal oxide is confined in a pore channel of the carrier; the preparation method comprises the following steps: (1) adding ferric salt and bismuth salt into a solvent, fully dissolving, then adding petal-type mesoporous silica, fully mixing, and drying; and (2) roasting the material dried in the step (1) in inert gas, and then roasting in air to obtain the catalyst. According to the preparation method, ferric oxide is introduced on the basis of a bismuth oxide catalyst, the petal-shaped mesoporous silica serving as a carrier is introduced, bismuth oxide and ferric oxide are confined in channels of the carrier, the reaction activity of the catalyst for catalyzing isocyanate and hydroxyl is improved, and the post-curing time of glue is shortened.

Description

Technical Field

[0001] The invention relates to a catalyst, in particular to a bismuth-based catalyst and a preparation method and application thereof. Background Art

[0002] As the automotive industry continues to develop, the performance and quality of car ceilings, as an important material for interior decoration, are directly related to the comfort and safety of the vehicle. Glue for car ceilings plays a vital role in the automobile manufacturing process. It can not only firmly adhere the ceiling material to the car body, but also improve the sound insulation and heat insulation performance of the ceiling, and enhance the driving experience. At the same time, the ceiling glue can also prevent the ceiling material from falling off and deforming during use, ensuring the safety of the vehicle.

[0003] In practical applications, there are many factors that affect the performance of automobile ceiling glue. Among them, the catalyst has a great influence on the stability and adhesion of its automobile ceiling glue. At present, the catalysts used to prepare automobile ceiling glue are mostly amine catalysts and tin catalysts. Although the automobile ceiling glue prepared by amine catalysts has strong adhesion, it is easy to absorb water, and there are risks and problems in stability. The automobile ceiling glue prepared by tin catalysts has excellent stability and adhesion, but some tin catalysts have high costs that limit their application. In addition, tin catalysts have potential toxicity problems, which increase the health risks to operators and also limit their widespread use to a certain extent. Most of them now use organic bismuth catalysts, but they are particularly sensitive to moisture and become inactivated during storage, causing the bonding strength of the ceiling glue to drop sharply. In addition, for the operating process, a single bismuth catalyst cannot achieve good strength in a short time in the application of ceiling glue. Summary of the invention

[0004] Purpose of the invention: The first purpose of the present invention is to provide a bismuth-based catalyst that improves catalytic activity and shortens the post-aging time of automobile ceiling glue; the second purpose of the present invention is to provide a method for preparing the bismuth-based catalyst; the third purpose of the present invention is the use of the bismuth-based catalyst in the preparation of automobile ceiling glue.

[0005] The bismuth-based catalyst of the present invention comprises a carrier and bismuth oxide and iron oxide loaded on the carrier. The carrier is petal-shaped mesoporous silica, and the metal oxide is confined in the pores of the carrier.

[0006] Preferably, the molar ratio of iron to bismuth is 0.4 to 1.3: 1. Bismuth catalyst alone cannot achieve good strength in a short time in the application of ceiling glue. By combining iron oxide with bismuth oxide, the rapid reaction of isocyanate and hydroxyl is promoted, and the subsequent aging time is shortened.

[0007] The method for preparing the bismuth-based catalyst of the present invention comprises the following steps:

[0008] (1) adding iron salt and bismuth salt to a solvent and fully dissolving them, then adding petal-shaped mesoporous silica, mixing them fully, and drying;

[0009] (2) The material dried in step (1) is first calcined in an inert gas and then calcined in air to obtain the catalyst.

[0010] The calcination in the inert gas and the calcination temperature are both 370-450° C. The calcination is first carried out in the inert gas for 3-5 hours, and finally in the air for 3-5 hours.

[0011] During the calcination process, the metal oxides generated by the oxidative decomposition of the metal salt are confined in the pores of the carrier.

[0012] Preferably, the drying is: drying the fully mixed solution in a vacuum oven at 90-110°C.

[0013] Preferably, in step (1), the solvent is ethanol, triethanolamine or ethylenediaminetetraacetate (EDTA disodium or tetrasodium). The solvent is both a solvent and a complexing agent, which can increase the stability of metal ions to form complexes for better load confinement.

[0014] Preferably, in step (1), the iron salt is selected from one of ferric nitrate, ferric sulfate and ferric chloride; the bismuth salt is selected from one of bismuth sulfate, bismuth nitrate and bismuth arsenate.

[0015] Preferably, the method for preparing the petal-shaped mesoporous silica comprises the following steps:

[0016] (1) 27 to 32 parts of cyclohexane, 0.4 to 2 parts of n-pentanol and 0.9 to 4.6 parts of tetraethyl orthosilicate are mixed uniformly by weight to obtain liquid A; 0.1 to 2 parts of hexadecyltrimethylammonium bromide and 0.1 to 1 part of urea are uniformly dissolved in 32 to 45 parts of water to obtain liquid B;

[0017] (2) While liquid A is being stirred, liquid B is then poured into liquid A and mixed thoroughly to obtain a mixed liquid;

[0018] (3) reacting the mixed solution obtained in step (3) at 90-110° C. for 3-5 hours, and cooling after the reaction is completed;

[0019] (4) Demulsifying the cooled solution, then letting it stand, taking out the solid, drying it, and finally calcining it at 500-600° C. for 5-7 hours to obtain a white powder, which is a petal-shaped mesoporous silica carrier.

[0020] The invention discloses an application of the bismuth-based catalyst in the preparation of polyurethane materials.

[0021] Preferably, the bismuth-based catalyst is used in the automobile ceiling adhesive as follows: firstly, 23 to 38 parts (by weight) of polyether polyol and 71 to 89 parts of isocyanate are stirred at 75 to 80° C. for 1.5 to 2 hours, and then cooled to 40 to 50° C.

[0022] 0.01-0.08 parts of phosphoric acid (mass fraction 85%) were added and stirred for 10-15 minutes, and then 0.04-0.18 parts of the bismuth-based catalyst were added, and the stirring reaction was continued for 20 minutes, and the material was collected.

[0023] Preferably, the polyurethane material is automobile roof glue.

[0024] Invention mechanism: Bismuth metal is easily exposed to water when exposed to the air, and thus easily loses its activity. To solve this problem, the present invention introduces a petal-shaped mesoporous silica carrier to confine bismuth oxide and iron oxide in the pores of the carrier, greatly reducing the contact between metal oxides and water, thereby improving the activity of the catalyst. Bismuth catalysts alone cannot achieve good strength in a short period of time in the application of ceiling glue. By combining iron oxide with bismuth oxide, the rapid reaction of isocyanate and hydroxyl is promoted, shortening the subsequent aging time.

[0025] Beneficial effects: Compared with the prior art, the present invention has the following advantages: (1) by introducing iron oxide on the basis of bismuth oxide catalyst and introducing petal-shaped mesoporous silica as a carrier, bismuth oxide and iron oxide are confined in the pores of the carrier, thereby improving the reaction activity of the catalyst for isocyanate and hydroxyl, and shortening the post-ripening time of the glue; (2) the catalyst has environmental protection performance, does no harm to operators, and has a relatively low price cost; (3) the preparation method is simple and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a scanning electron microscope image of the bismuth-based catalyst prepared in Example 1;

[0027] Figure 2 This is a transmission electron microscopy image of the bismuth-based catalyst prepared in Example 1. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific embodiments.

[0029] Example 1

[0030] The bismuth-based catalyst of the present invention has a preparation method comprising the following steps:

[0031] 1. Preparation of petal-shaped catalyst

[0032] (1) Weigh 36 mL of cyclohexane, 2.1 mL of n-pentanol, and 3 mL of tetraethyl orthosilicate (TEOS) into a beaker and mix them evenly at room temperature. The mixed solution is called solution A.

[0033] (2) Weigh 1.2 g of hexadecyltrimethylammonium bromide (CTAB) and 0.7 g of urea and evenly dissolve them in 37 mL of water. The resulting mixed solution is called solution B.

[0034] (3) Place the prepared solution A on an electromagnetic stirrer and stir slowly. Then slowly pour solution B into solution A at room temperature. Increase the stirring rate and stir at room temperature for 30 minutes to ensure thorough mixing.

[0035] (4) placing the obtained solution into a high pressure reactor, heating it in an oil bath at 100° C. for 4 h, and then cooling it to room temperature;

[0036] (5) 10 mL of anhydrous ethanol was added to the cooled solution to break the emulsion, and the solution was allowed to stand for 30 h. The upper liquid was then removed and the remaining liquid was centrifuged. The solid after centrifugation was evaporated in an oven at 80 ° C overnight. Finally, the dried sample was calcined in air at 550 ° C in a muffle furnace for 6 h to obtain a white powder, which is a petal-shaped mesoporous silica carrier.

[0037] 2. Preparation of Bismuth-based Catalysts

[0038] (1) Weigh 0.4 mol of ferric nitrate and 1 mol of bismuth nitrate into a beaker, then add 5 mL of ethylene glycol as a complexing agent and stir to fully dissolve them, then weigh 0.5 g of a white powder petal-shaped mesoporous silica carrier and stir it at room temperature overnight to obtain a fully mixed solution;

[0039] (2) placing the prepared solution into a vacuum oven, drying it at 100° C. for 24 h, taking it out and placing it into a tubular furnace for calcination, first calcining it at 400° C. in nitrogen for 4 h, and finally calcining it in air for 4 h, to obtain the bismuth-based catalyst.

[0040] Example 2

[0041] On the basis of Example 1, the molar amount of ferric nitrate was changed to 0.8 mol, and the other conditions remained unchanged.

[0042] Example 3

[0043] On the basis of Example 1, the molar amount of ferric nitrate was changed to 1.1 mol, and the other conditions remained unchanged.

[0044] Example 4

[0045] On the basis of Example 1, the molar amount of ferric nitrate was changed to 1.3 mol, and the other conditions remained unchanged.

[0046] Comparative Example 1

[0047] On the basis of Example 1, the petal-shaped mesoporous silica was replaced with ordinary mesoporous silica spheres, and the other conditions remained unchanged.

[0048] Comparative Example 2

[0049] On the basis of Example 1, the molar amount of ferric nitrate was changed to 0.15 mol, and the other conditions remained unchanged.

[0050] Comparative Example 3

[0051] On the basis of Example 1, the molar amount of ferric nitrate was changed to 2 mol, and the other conditions remained unchanged.

[0052] Structural characterization

[0053] The bismuth-based catalyst prepared in Example 1 was characterized by scanning electron microscopy and transmission electron microscopy. Figure 1 and Figure 2 shown.

[0054] Depend on Figure 1 It can be seen that the catalyst prepared in Example 1 presents a petal shape. Figure 2 It can be seen that the metal particles are evenly dispersed in the pores of the carrier and are well confined in the pores of the carrier.

[0055] Performance Testing

[0056] The catalysts prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were used in the preparation of automobile ceiling adhesives: 31.2 g of polyether polyol (functionality 2 to 3, molecular weight 1000 to 5000) and 85 g of isocyanate were stirred at 80° C. for 2 h, cooled to 50° C., 0.04 g of 85% phosphoric acid was added, stirred for 10 min, and then 0.1 g of

[0057] catalyst, continue stirring the reaction for 20 min, and collect the material.

[0058] The open time test of the ceiling glue was conducted: 30g of the ceiling glue was poured into a disposable cup, exposed to an environment of 23±2℃ and 45±5% humidity, and its skinning time was observed. The test results are detailed in Table 1.

[0059] Initial strength test of the ceiling glue: evenly apply the ceiling glue on both sides of the PU board, laminate glass fiber and non-woven fabric, press for 60 seconds at 135-140℃, and use a hardness tester to test the strength at the moment of demolding. The test results are detailed in Table 1.

[0060] Table 1 Test results of ceiling adhesive performance

[0061]

[0062]

[0063] Initial strength: JB / T 6148—2017

[0064] From the data in Table 1, it can be seen that the automobile roof glue prepared by the catalysts prepared in Examples 1 to 4 has a strong initial strength and a long open time, which greatly improves the glue application time and the post-aging speed when preparing the automobile roof in actual operation. As the molar ratio of iron oxide to bismuth oxide increases, the initial strength gradually increases, but the open time decreases slightly.

[0065] In Comparative Example 1, iron and bismuth metals are loaded on ordinary silica balls, and the post-aging time is long, resulting in a decrease in initial strength. This is because the metals loaded on ordinary silica balls are easily exposed to the air, causing some of the metals to lose activity and reducing the active centers participating in the reaction.

[0066] In Comparative Example 2, the molar amount of metallic iron is reduced, resulting in failure to achieve good synergistic effect, thereby affecting the post-ripening speed and reducing the initial strength.

[0067] In comparative example 3, the molar amount of metallic iron increases, which improves the catalytic rate at room temperature, so that the glue exposed on the production roller promotes the reaction of isocyanate with water in the air, greatly shortening the open time and affecting the workers' operating time.

Claims

1. A bismuth-based catalyst, characterized in that The invention comprises a carrier and metal bismuth oxide and iron oxide loaded on the carrier. The carrier is petal-shaped mesoporous silica, and the metal oxide is confined in the pores of the carrier.

2. The bismuth-based catalyst according to claim 1, characterized in that The molar ratio of iron to bismuth is 0.4-1.3:

1.

3. A method for preparing the bismuth-based catalyst according to any one of claims 1 or 2, characterized in that: The following steps are involved: (1) adding iron salt and bismuth salt to a solvent, fully dissolving them, then adding petal-shaped mesoporous silica, mixing them thoroughly, and drying; (2) The material dried in step (1) is first calcined in an inert gas and then calcined in air to obtain the catalyst.

4. The method for preparing a bismuth-based catalyst according to claim 3, characterized in that: The calcination temperature in the inert gas and in the air is both 370-450°C.

5. The method for preparing a bismuth-based catalyst according to claim 3, characterized in that: The drying step is: drying the fully mixed solution in a vacuum box at 90-110°C.

6. The method for preparing a bismuth-based catalyst according to claim 3, characterized in that: In step (1), the solvent is ethanol, triethanolamine or ethylenediaminetetraacetate (disodium or tetrasodium EDTA).

7. The method for preparing a bismuth-based catalyst according to claim 3, characterized in that: In step (1), the iron salt is selected from one of ferric nitrate, ferric sulfate and ferric chloride; the bismuth salt is selected from one of bismuth sulfate, bismuth nitrate and bismuth arsenate.

8. The method for preparing a bismuth-based catalyst according to claim 3, characterized in that: The preparation method of the petal-shaped mesoporous silica comprises the following steps: (1) 27 to 32 parts of cyclohexane, 0.4 to 2 parts of n-pentanol and 0.9 to 4.6 parts of tetraethyl orthosilicate are mixed uniformly by weight to obtain liquid A; 0.1 to 2 parts of hexadecyltrimethylammonium bromide and 0.1 to 1 part of urea are uniformly dissolved in 32 to 45 parts of water to obtain liquid B; (2) While liquid A is being stirred, liquid B is then poured into liquid A and mixed thoroughly to obtain a mixed liquid; (3) reacting the mixed solution obtained in step (2) at 90-110° C. for 3-5 hours, and cooling after the reaction is completed; (4) Demulsifying the cooled solution, then letting it stand, taking out the solid, drying it, and finally calcining it at 500-600° C. for 5-7 hours to obtain a white powder, which is a petal-shaped mesoporous silica carrier.

9. Use of the bismuth-based catalyst according to any one of claims 1 or 2 in the preparation of polyurethane materials.

10. The use according to claim 9, characterized in that: The polyurethane material is automobile roof glue.

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