Catalyst and application thereof in preparation of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol

Abstract

The invention provides a catalyst and application thereof in preparation of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, and belongs to the technical field of catalysts, the catalyst takes porous calcium titanate microspheres as a carrier, and takes nickel and molybdenum as active components. When the catalyst is applied to preparation of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, the TMCB conversion rate and the main reaction selectivity (CBDO selectivity) can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and particularly relates to a catalyst and application thereof in the preparation of 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Background Art

[0002] 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (CBDO) is an aliphatic diol and an important raw material for the synthesis of high-performance polyesters. Copolyesters are considered an ideal alternative to PC, and the preparation process of 2,2,4,4-tetramethyl-1,3-cyclobutanediol is particularly valuable for the synthesis of high-performance polyesters.

[0003] Existing technology primarily produces 2,2,4,4-tetramethyl-1,3-cyclobutanediol through the hydrogenation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB). The catalyst for 2,2,4,4-tetramethyl-1,3-cyclobutanedione hydrogenation is primarily a metal-supported catalyst, such as a supported nickel-based catalyst. Due to the low cost of nickel, it is loaded onto alumina or silica gel supports via an impregnation method, a mature process. The reaction rate is rapid under high temperature (180-220°C) and high pressure (4.0-6.0 MPa) conditions.

[0004] However, alumina-supported nickel-based catalysts have the following disadvantages: 1. When alumina is used as a support, the acidic sites on the alumina surface trigger condensation side reactions or excessive hydrogenation, reducing the selectivity of the target product; 2. During the hydrogenation reaction, after TMCB (2,2,4,4-tetramethyl-1,3-cyclobutanedione) is adsorbed on the nickel active sites, the hydrogen dissociation rate is insufficient (such as low hydrogen partial pressure or too high temperature), and some intermediates that are not hydrogenated in time (such as enol intermediates) polymerize to form large molecular coke, covering the active sites. Carbon deposits cover the nickel surface, hindering the adsorption of reactants and hydrogen dissociation, resulting in a decrease in conversion rate. Summary of the Invention

[0005] To solve the problems existing in the background technology, the present invention provides a catalyst and its application in the preparation of 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A catalyst using porous calcium titanate microspheres as a carrier and nickel and molybdenum as active components; the preparation method of the catalyst is as follows:

[0008] S1. Ammonium molybdate is prepared into a solution with a concentration of 5-10 wt% with deionized water to obtain a molybdenum precursor solution; nickel nitrate is prepared into a solution with a concentration of 10-15 wt% with deionized water to obtain a nickel precursor solution;

[0009] S2, immersing the porous calcium titanate microspheres in the molybdenum precursor solution at a liquid-solid ratio of (3-5):1, ultrasonically immersing for 2-4 hours, filtering, drying and calcining for the first time, immersing the porous calcium titanate microspheres in the nickel precursor solution at a liquid-solid ratio of (3-5):1, standing for 4-6 hours, filtering, drying and calcining for the second time, and obtaining a catalytic precursor;

[0010] S3. Placing the catalytic precursor in a tubular furnace and calcining it for the third time to obtain a catalyst.

[0011] Furthermore, in S2, the specific operations of the first drying and calcination are: drying in an oven at 80-100°C for 6-8 hours, and calcining at 400-500°C in an air atmosphere for 2-4 hours.

[0012] Furthermore, in S2, the specific operations of the second drying and calcination are: drying in an oven at 100-120°C for 4-6 hours, and calcining at 450-550°C for 3-5 hours under a nitrogen atmosphere.

[0013] Furthermore, in S3, the specific operation of the third calcination is as follows: introducing H2 / N2 mixed gas into the tubular furnace, with the H2 volume fraction being 5-10%, raising the temperature to 400-500°C at 2-5°C / min, and maintaining the temperature for 2-4h.

[0014] Furthermore, the preparation method of the porous calcium titanate microspheres is as follows:

[0015] A1, pre-treating the template D311 resin to obtain pre-treated D311 resin;

[0016] A2. Dissolve tetrabutyl titanate and calcium nitrate in anhydrous ethanol at a calcium-to-titanium molar ratio of 1:1, add citric acid as a complexing agent, stir, and adjust the pH to 3-5 with aqueous ammonia to obtain a calcium titanate precursor sol;

[0017] A3, placing the pretreated D311 resin obtained in A1 into the calcium titanate precursor sol obtained in A2, impregnating for 2-3 hours, drying, and then placing in a muffle furnace at 800-900°C, calcining for 2 hours in an air atmosphere, and naturally cooling to room temperature in the furnace to obtain a composite material;

[0018] A4. Immerse the composite material obtained in A3 in a nitric acid solution, wash, and dry to obtain porous calcium titanate microspheres.

[0019] Furthermore, in A1, the specific operation of pretreatment is: soaking the template D311 resin in a 0.1M hydrochloric acid solution, and then soaking it in ethanol, each soaking time is 1 hour, and then rinsing it with deionized water until it is neutral and drying it to obtain the pretreated D311 resin.

[0020] Furthermore, in A2, the molar amount of the citric acid is 1.1-1.4 times the total molar amount of titanium and calcium; and the concentration of the ammonia water is 5-10 wt%.

[0021] Furthermore, in A3, the drying temperature is 50-80° C. and the drying time is 12 h.

[0022] Furthermore, in A4, the concentration of the nitric acid solution is 2-3 mol / L, the soaking time is 30-50 min; distilled water is used for washing until neutral; and drying is carried out at 100-105° C. for 50-60 min.

[0023] An application of the catalyst in the preparation of 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

[0024] This application has the following beneficial effects:

[0025] 1. The catalyst of the present invention uses porous calcium titanate microspheres as carriers and nickel and molybdenum as active components. After the porous calcium titanate microspheres are loaded with molybdenum, a Mo-O-Ti composite structure is formed, covering the Ti 4+ Acidic sites reduce the surface acidity strength, inhibit the CO bond rupture path, reduce the carbon deposition rate, and effectively avoid hindering the adsorption of reactants; the electron transfer from Mo to Ni weakens the d-band center of Ni, reduces the strong adsorption of intermediates, promotes the release of active hydrogen, and the Ni-Mo interface promotes the heterolytic dissociation of hydrogen, so that its hydrogen dissociation rate is higher than that of the pure Ni system, thereby synergistically improving the TMCB conversion rate.

[0026] 2. The introduction of Mo expands the hydrogen migration channel, shortens the transmission distance of active hydrogen from Ni to the adsorbed ketone site, and improves the reaction rate. Mo acts as a hydrogen overflow promoter, lowering the hydrogen dissociation energy barrier and enabling hydrogen atoms to efficiently migrate to adjacent nickel active sites. This hydrogen overflow network breaks through the hydrogenation rate bottleneck of traditional single metals, while suppressing the β-H elimination side reaction pathway, thereby synergistically improving the main reaction selectivity (CBDO selectivity). DETAILED DESCRIPTION

[0027] The present application is further described in detail below with reference to the embodiments.

[0028] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0029] Example 1: (1) Preparation of porous calcium titanate microspheres, the preparation method is as follows:

[0030] A1. Soak the template D311 resin in a 0.1M hydrochloric acid solution and then in ethanol for 1 hour each. Rinse with deionized water until neutral and dry to obtain a pretreated D311 resin.

[0031] A2. Tetrabutyl titanate and calcium nitrate are dissolved in anhydrous ethanol at a calcium-to-titanium molar ratio of 1:1, citric acid is added as a complexing agent, the molar amount of citric acid being 1.2 times the total molar amount of titanium and calcium, and stirred to form a sol. The pH is adjusted to about 4 with ammonia water, and the concentration of ammonia water is 8wt%, to obtain a calcium titanate precursor sol.

[0032] A3: The pretreated D311 resin obtained in A1 was placed in the calcium titanate precursor sol obtained in A2. After impregnation for 2.5 hours, the sol was dried in a drying oven at 70°C for 12 hours. The sol was then calcined in a muffle furnace at 850°C in air for 2 hours. The temperature was then decreased from 850°C to 600°C at a rate of 3°C / min, and then naturally cooled to room temperature in the furnace to obtain a composite material.

[0033] A4. Immerse the composite material obtained in A3 in a nitric acid solution with a concentration of 2.5 mol / L for 40 minutes, using ultrasound (40 kHz, 30 minutes). Wash with distilled water until neutral, and then dry at 100°C for 60 minutes to obtain porous calcium titanate microspheres with a pore size of 10-30 nm.

[0034] (2) Prepare the catalyst, and its preparation method is as follows:

[0035] S1. Prepare a molybdenum precursor solution and a nickel precursor solution.

[0036] Ammonium molybdate (NH4)6Mo7O 24 Dissolve 4H2O in deionized water to a concentration of 8wt% and stir until completely dissolved to obtain a molybdenum precursor solution. Dissolve nickel nitrate (Ni(NO3)2·6H2O) in deionized water and add a small amount of citric acid as a complexing agent to improve dispersibility. The mass of citric acid is 2% of the nickel nitrate to prepare a solution with a concentration of 12wt%, which is the nickel precursor solution.

[0037] S2. Impregnation in steps, specifically, impregnating the molybdenum precursor solution first, and then impregnating the nickel precursor solution after drying.

[0038] Porous calcium titanate microspheres were immersed in a molybdenum precursor solution at a liquid-to-solid ratio of 4:1. Ultrasonic-assisted impregnation was performed for three hours to ensure sufficient adsorption of the molybdenum precursor into the micropores. After filtration, the microspheres were oven-dried at 90°C for seven hours to remove moisture and physically adsorbed impurities. The microspheres were then calcined at 450°C in air for three hours to decompose the molybdenum precursor into MoO3, which then bonded to the support surface.

[0039] The molybdenum-loaded support was immersed in a nickel precursor solution at a liquid-to-solid ratio of 4:1 and allowed to stand at room temperature for 5 hours. After filtration, the solution was oven-dried at 110°C for 5 hours. The solution was then calcined at 500°C for 4 hours under a nitrogen atmosphere to decompose the nickel nitrate into NiO and prevent high-temperature oxidation.

[0040] S3. Place the calcined catalyst in a tubular furnace, introduce a H2 / N2 mixed gas (H2 volume fraction 8%), raise the temperature to 450°C at 3°C / min, and maintain for 3 hours to reduce NiO and MoO3 to metallic Ni and Mo, respectively, to obtain the catalyst.

[0041] Example 2: The difference between this example and Example 1 is that the catalyst is prepared by the following method:

[0042] S1. Prepare a molybdenum precursor solution and a nickel precursor solution.

[0043] Ammonium molybdate (NH4)6Mo7O 24 Dissolve 4H2O in deionized water to a 5wt% concentration and stir until completely dissolved to obtain a molybdenum precursor solution. Dissolve nickel nitrate (Ni(NO3)2·6H2O) in deionized water and add a small amount of citric acid as a complexing agent to improve dispersibility. The mass of citric acid is 2% of the nickel nitrate. Prepare a 10wt% solution to obtain a nickel precursor solution.

[0044] S2. Impregnation in steps, specifically, impregnating the molybdenum precursor solution first, and then impregnating the nickel precursor solution after drying.

[0045] Porous calcium titanate microspheres were immersed in a molybdenum precursor solution at a liquid-to-solid ratio of 5:1. Ultrasonic-assisted impregnation was performed for four hours to ensure sufficient adsorption of the molybdenum precursor into the micropores. After filtration, the microspheres were oven-dried at 100°C for six hours to remove moisture and physically adsorbed impurities. The microspheres were then calcined at 500°C in air for two hours to decompose the molybdenum precursor into MoO3, which then bonded to the support surface.

[0046] The molybdenum-loaded support was immersed in a nickel precursor solution at a liquid-to-solid ratio of 5:1 and allowed to stand at room temperature for 6 hours. After filtration, the solution was oven-dried at 120°C for 4 hours. The solution was then calcined at 550°C for 3 hours under a nitrogen atmosphere to decompose the nickel nitrate into NiO and prevent high-temperature oxidation.

[0047] S3. Place the calcined catalyst in a tubular furnace, introduce a H2 / N2 mixed gas (H2 volume fraction 10%), raise the temperature to 500°C at 5°C / min, and maintain for 2 hours to reduce NiO and MoO3 to metallic Ni and Mo, respectively, to obtain the catalyst.

[0048] Example 3: The difference between this example and Example 1 is that the catalyst is prepared by the following method:

[0049] S1. Prepare a molybdenum precursor solution and a nickel precursor solution.

[0050] Ammonium molybdate (NH4)6Mo7O 24Dissolve 4H2O in deionized water to a 10wt% concentration and stir until completely dissolved to obtain a molybdenum precursor solution. Dissolve nickel nitrate (Ni(NO3)2·6H2O) in deionized water and add a small amount of citric acid as a complexing agent to improve dispersibility. The mass of citric acid is 2% of the nickel nitrate. Prepare a 15wt% solution to obtain a nickel precursor solution.

[0051] S2. Impregnation in steps, specifically, impregnating the molybdenum precursor solution first, and then impregnating the nickel precursor solution after drying.

[0052] Porous calcium titanate microspheres were immersed in a molybdenum precursor solution at a liquid-to-solid ratio of 3:1. Ultrasonic-assisted impregnation was performed for two hours to ensure sufficient adsorption of the molybdenum precursor into the micropores. After filtration, the microspheres were oven-dried at 80°C for eight hours to remove moisture and physically adsorbed impurities. The microspheres were then calcined at 400°C in air for four hours to decompose the molybdenum precursor into MoO3, which then bonded to the support surface.

[0053] The molybdenum-loaded support was immersed in a nickel precursor solution at a liquid-to-solid ratio of 3:1 and allowed to stand at room temperature for 4 hours. After filtration, the solution was oven-dried at 100°C for 6 hours. The solution was then calcined at 450°C for 5 hours under a nitrogen atmosphere to decompose the nickel nitrate into NiO and prevent high-temperature oxidation.

[0054] S3. Place the calcined catalyst in a tubular furnace, introduce a H2 / N2 mixed gas (H2 volume fraction 5%), raise the temperature to 400°C at 2°C / min, and maintain for 4 hours to reduce NiO and MoO3 to metallic Ni and Mo, respectively, to obtain the catalyst.

[0055] Comparative Example 1: This comparative example differs from Example 1 only in that the porous calcium titanate microspheres in the catalyst are replaced with alumina, and molybdenum is deleted. That is, the catalyst uses alumina as a carrier and nickel as an active component.

[0056] Comparative Example 2: This comparative example differs from Example 1 only in that molybdenum is deleted from the catalyst. That is, the catalyst uses porous calcium titanate microspheres as a carrier and nickel as an active component.

[0057] Comparative Example 3: This comparative example differs from Example 1 only in that the porous calcium titanate microspheres in the catalyst are replaced with alumina. That is, the catalyst uses alumina as a carrier and nickel and molybdenum as active components.

[0058] Test Example: The catalysts prepared in Examples 1-3 and Comparative Examples 1-3 were used to hydrogenate 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB) to produce 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO). The TMCB conversion and CBDO selectivity after ten hydrogenation cycles were calculated. The test results are shown in Table 1.

[0059] Table 1. Test example data

[0060] TMCB conversion rate (%) CBDO selectivity (%) Example 1 99.12 96.45 Example 2 99.53 97.03 Example 3 99.07 96.49 Comparative Example 1 94.74 91.39 Comparative Example 2 92.23 90.07 Comparative Example 3 97.31 93.14

[0061] Analysis of results: By analyzing Examples 1 to 3 and combining them with the data in Table 1, it can be seen that the catalysts prepared in the present invention (Examples 1 to 3) are used to prepare 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) by hydrogenation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB). The TMCB conversion rate is as high as over 99.07%, and the CBDO selectivity is as high as over 96.45%.

[0062] By analyzing Example 1 and Comparative Examples 1 to 3 and combining them with the data in Table 1, specifically comparing Comparative Example 1 with Comparative Example 2, it can be seen that compared to Comparative Example 1, in which the catalyst uses alumina as a support and nickel as an active component, Comparative Example 2 replaces the support alumina with porous calcium titanate microspheres. The results show that the conversion of TMCB and the selectivity of CBDO in the preparation of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) by hydrogenation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB) decreased instead of increased. This indicates that when the active component of the catalyst is nickel, changing the support from alumina to porous calcium titanate microspheres will result in a decrease in the conversion of TMCB and the selectivity of CBDO in the catalyst application.

[0063] This is because the ketone adsorption strength in the nickel-porous calcium titanate microsphere system is higher than that in nickel-alumina, but the selective hydrogenation efficiency is hindered by side reactions; the surface of porous calcium titanate microspheres contains strong Lewis acid sites of Ti4+, and when nickel is loaded alone, the CO bond cleavage activity of 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB) is significantly enhanced, resulting in the formation of unsaturated intermediates such as olefins and inducing condensation carbon deposition, which hinders the adsorption of reactants and hydrogen dissociation, resulting in a decrease in conversion rate; at the same time, excessively adsorbed ketone groups (C=O) induce dehydrogenation side reactions, resulting in a decrease in the selectivity of the main reaction (CBDO selectivity).

[0064] By comparing Comparative Example 1 and Comparative Example 3, it can be seen that compared with the catalyst in Comparative Example 1, which uses alumina as a carrier and nickel as an active component, the active component of the catalyst in Comparative Example 3 increases molybdenum on the basis of nickel. As a result, the TMCB conversion rate and CBDO selectivity in the preparation of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) by hydrogenation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB) are improved.

[0065] By comparison with Example 1, it can be seen that when the active components are nickel and molybdenum, changing the catalyst support from alumina to porous calcium titanate microspheres can further improve the TMCB conversion rate and CBDO selectivity in the catalyst application. This shows that in the presence of the active component nickel, the porous calcium titanate microspheres support and the active component molybdenum can produce a synergistic effect, synergistically improving the TMCB conversion rate and CBDO selectivity of the prepared catalyst in the preparation of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) by hydrogenation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB).

[0066] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0067] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A catalyst, characterized in that The porous calcium titanate microspheres are used as carriers, and nickel and molybdenum are used as active components. The preparation method of the catalyst is as follows: S1. Ammonium molybdate is prepared into a solution with a concentration of 5-10 wt% with deionized water to obtain a molybdenum precursor solution; nickel nitrate is prepared into a solution with a concentration of 10-15 wt% with deionized water to obtain a nickel precursor solution; S2, immersing the porous calcium titanate microspheres in the molybdenum precursor solution at a liquid-solid ratio of (3-5):1, ultrasonically immersing for 2-4 hours, filtering, drying and calcining for the first time, immersing the porous calcium titanate microspheres in the nickel precursor solution at a liquid-solid ratio of (3-5):1, standing for 4-6 hours, filtering, drying and calcining for the second time, and obtaining a catalytic precursor; S3. Placing the catalytic precursor in a tubular furnace and calcining it for the third time to obtain a catalyst.

2. The catalyst according to claim 1, characterized in that In S2, the specific operations of the first drying and calcination are: drying in an oven at 80-100°C for 6-8 hours, and calcining at 400-500°C in an air atmosphere for 2-4 hours.

3. The catalyst according to claim 1, characterized in that In S2, the specific operations of the second drying and calcination are: drying in an oven at 100-120°C for 4-6 hours, and calcining at 450-550°C for 3-5 hours under a nitrogen atmosphere.

4. The catalyst according to claim 1, characterized in that In S3, the specific operation of the third calcination is as follows: introducing H2 / N2 mixed gas into the tubular furnace, with the H2 volume fraction of 5-10%, heating to 400-500°C at 2-5°C / min, and maintaining for 2-4h.

5. The catalyst according to claim 1, characterized in that The preparation method of the porous calcium titanate microspheres is as follows: A1, pre-treating the template D311 resin to obtain pre-treated D311 resin; A2. Dissolve tetrabutyl titanate and calcium nitrate in anhydrous ethanol at a calcium-to-titanium molar ratio of 1:1, add citric acid as a complexing agent, stir, and adjust the pH to 3-5 with aqueous ammonia to obtain a calcium titanate precursor sol; A3, placing the pretreated D311 resin obtained in A1 into the calcium titanate precursor sol obtained in A2, impregnating for 2-3 hours, drying, and then placing in a muffle furnace at 800-900°C, calcining for 2 hours in an air atmosphere, and cooling to room temperature to obtain a composite material; A4. Immerse the composite material obtained in A3 in a nitric acid solution, wash, and dry to obtain porous calcium titanate microspheres.

6. The catalyst according to claim 5, characterized in that In A1, the specific operation of pretreatment is: soaking the template D311 resin in a 0.1M hydrochloric acid solution and then in ethanol, each soaking time is 1 hour, and then rinsed with deionized water until neutral and dried to obtain the pretreated D311 resin.

7. The catalyst according to claim 5, characterized in that In A2, the molar amount of the citric acid is 1.1-1.4 times the total molar amount of titanium and calcium; and the concentration of the ammonia water is 5-10 wt%.

8. The catalyst according to claim 5, characterized in that In A3, the drying temperature is 50-80°C and the drying time is 12h.

9. The catalyst according to claim 1, characterized in that In A4, the concentration of the nitric acid solution is 2-3 mol / L, and the soaking time is 30-50 min; the product is washed with distilled water until neutral; and dried at 100-105° C. for 50-60 min.

10. Use of the catalyst according to any one of claims 1 to 9 in the preparation of 2,2,4,4-tetramethyl-1,3-cyclobutanediol.