Preparation method of copper-palladium bimetallic catalyst and application thereof

Abstract

The application discloses a preparation method of a copper-palladium bimetallic catalyst and application of the catalyst, and the catalyst is prepared by a hydrothermal method and takes silica as a carrier and a copper-palladium composite metal oxide as an active component. The copper-palladium composite metal oxide is loaded on the surface of the silica in the form of nanometer small balls, and through the synergistic effect of the copper-palladium oxide, high conversion rate and high selectivity of bimorpholine diethyl ether synthesis are realized. The method has simple steps, is environment-friendly, and has a wide market application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a copper-palladium bimetallic catalyst and application thereof, and belongs to the technical field of special chemical synthesis. BACKGROUND

[0002] Dimorpholinodiethylether (DMDEE) is a strong polyurethane foaming catalyst, and the steric hindrance effect of the amino group can make the prepolymer containing isocyanate components have good stability, and the DMDEE has a wide application in the polyurethane industry. With the continuous expansion of the demand for DMDEE, it is urgent to find a green and efficient synthesis process.

[0003] At present, the main production method of DMDEE is to use an intermittent reaction for synthesis, for example, dimorpholinodiethylether is synthesized by using dichloroethane and morpholine as raw materials, and the method is not only complicated in steps, but also toxic and harmful. Synthesizing dimorpholinodiethylether by using morpholine and diethylene glycol under the action of a catalyst is a potential alternative method, and currently, there are few reports on such technology, and the representative is a multi-component metal catalyst disclosed in patent CN105289709A, which realizes high conversion rate and selectivity of DMDEE, but the catalyst has harsh conditions for synthesizing DMDEE, and the maximum reaction pressure can reach 150 atm. For example, patent CN109503516A reports a copper-palladium catalyst, adopts a noble metal palladium as a cocatalyst, and is synthesized by long-time super-high-temperature calcination, and has high catalytic efficiency and few by-products, but the catalyst is high in cost and short in service life, and is not suitable for industrial large-scale application. Therefore, it is urgent to develop a catalyst with high conversion rate, high selectivity and long service life. SUMMARY

[0004] The purpose of the application is to respond to the current market blank of dimorpholinodiethylether catalyst, and provide a preparation method of a copper-palladium bimetallic catalyst and application thereof.

[0005] The purpose of the application can be realized by the following technical scheme.

[0006] A preparation method of a copper-palladium bimetallic catalyst, characterized in that the catalyst takes fumed silica as a carrier, copper-palladium composite metal oxide as an active component, and ascorbic acid as a structure directing agent, and is prepared by using a hydrothermal synthesis method; and the mass percentage of cuprous oxide is 9-16% and the mass percentage of palladium oxide is 0.3-1.2% based on the mass of the carrier.

[0007] A copper-palladium bimetallic catalyst is prepared by the following method.

[0008] (1) fumed silica is fully mixed with a binder, a copper-palladium precursor mixture solution is configured, the two are uniformly mixed, and then are kneaded, extruded and formed, and dried.

[0009] (2) calcining the shaped mixture at 500-600 DEG C for 2-4 hours.

[0010] (3) adjusting the pH value of the ammonia water to 12-14, dissolving ascorbic acid in the ammonia water as a structure directing agent, and then immersing the calcined product in the ammonia water mixed solution to perform a hydrothermal reaction;

[0011] (4) collecting the product after the hydrothermal reaction, washing and drying to obtain a finished catalyst.

[0012] Specifically, the fumed silica in step (1) is hydrophilic fumed silica with a particle size of 1000-8000 mesh, preferably 6000-8000 mesh.

[0013] Specifically, the binder in step (1) is Tianqin powder, polyethylene oxide (PEO) or sodium carboxymethyl cellulose (CMC), and the mass percentage of the binder is 3-5% based on the mass of the carrier.

[0014] Specifically, the copper-palladium precursor in step (1) is a chloride salt of copper and palladium.

[0015] Specifically, the extrusion molding shape in step (1) is columnar, trilobal or quadrilobal, with a diameter of 2-6 mm, preferably 2-4 mm.

[0016] Specifically, the calcination temperature in step (2) is 500-600 DEG C, the calcination time is 2-4 hours, and the calcination environment is air atmosphere.

[0017] Specifically, the pH value of the ammonia water in step (3) is adjusted to 12-14, and ascorbic acid is dissolved in the ammonia water to form a mixed solution with an ascorbic acid concentration of 100-200 mmol / L.

[0018] Specifically, in the hydrothermal reaction in step (3), the mass ratio of the calcined product to the ammonia water mixed solution is 1:6-10, the hydrothermal reaction temperature is 130-150 DEG C, and the hydrothermal reaction time is 8-12 hours.

[0019] Advantages:

[0020] The application discloses a preparation method of a copper-palladium bimetallic catalyst, which fills the gap of the market catalytic synthesis of DMDEE technology. The catalyst has stable performance, long service life and broad market application prospect, and has the following specific advantages:

[0021] (1) Copper-palladium composite metal oxide as active component is loaded on fumed silica carrier in the form of nanometer small spheres. The unique process sequence ensures the uniformity of active component dispersion, and the selection of fumed silica as carrier makes the internal part of the catalyst rich in mesopores and macropores after extrusion molding, which significantly improves the specific surface area of the catalyst. In addition, the combination of Cu-Pd-Si-O makes the surface of the catalyst present Lewis acidity, which promotes the dehydration reaction of morpholine and diethylene glycol.

[0022] (2) Copper-palladium composite metal oxide is synthesized by hydrothermal method, in which the metal oxide of copper is Cu2O. Ascorbic acid is used as a structure directing agent to make Cu2O grow with high-activity (111) crystal surface, and the catalytic activity is excellent. At the same time, the hydrothermal synthesis method makes the copper-palladium metal oxide tightly combined on the carrier, avoiding the shedding of the active component and effectively improving the catalyst life.

[0023] (3) The introduction of palladium salt greatly reduces the reaction activation energy, and the synergistic effect of Cu2O and PdO realizes the efficient conversion of morpholine and diethylene glycol to bis-morpholine diethyl ether under relatively mild conditions. BRIEF DESCRIPTION OF DRAWINGS

[0024] ATTACHMENT Figure 1 Schematic diagram of evaluation device. DETAILED DESCRIPTION

[0025] The preparation method of the copper-palladium bimetallic catalyst and its application will be further illustrated by the following examples. The examples are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0026] In the following examples, the experimental methods are conventional methods in the field unless otherwise specified, and the experimental devices and experimental materials can be commercially available unless otherwise specified.

[0027] Performance evaluation method: the performance of the catalyst is evaluated by a fixed bed microreactor, the inner diameter of the reaction tube is 10 mm, and the length is 550 mm. The broken sieve selects the catalyst of 20-40 mesh, which is loaded in the middle part of the reaction tube with a loading height of 25 cm, and quartz sand is loaded below for support. The catalyst is activated by H2 reduction at 400℃ for 10h (H2 flow rate 100ml / min, pressure 3MPa), and then the performance evaluation is started. Morpholine and diethylene glycol are pre-mixed, the mass ratio of morpholine to diethylene glycol is 62:38, and the mixed solution is preheated to 190℃ and then enters the reactor at 0.15ml / min. During the reaction, H2 is kept flowing (100ml / min) and the pressure is kept stable (3MPa). The reactor temperature is 200℃, 210℃, 220℃, 230℃, 240℃ and 250℃, and each temperature point is kept constant for 2h to take samples and perform gas chromatography evaluation.

[0028]

[0029]

[0030]

[0031]

[0032] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 mass percentage of Cu2O 9％ 13％ 16％ 13％ 16％ PdO mass percent content 0.3％ 0.6％ 1.2％ 1％ 1.2％

[0033] Example 1

[0034] Synthesis of sample: 3.2170 g of CuCl2-2H2O and 0.1304 g of PdCl2 were weighed and dissolved in 10 ml of deionized water to form a mixed solution A. 30 g of 1000 mesh hydrophilic fumed silica (Guangzhou Yinnuo Chemical Technology Co., Ltd., Germany Wacker DeGussa R974 type) and 0.9 g of sodium carboxymethyl cellulose (CMC) were weighed and mixed uniformly. Mixed solution A was poured into the mixed powder and kneaded repeatedly, with moderate water added during the kneading until a dough was formed, and then extruded into 4 mm cylindrical intermediates. After complete drying at 80°C, the intermediates were transferred to a muffle furnace and calcined at 500°C for 2 h. 180 g of ammonia water with a pH value of 12 was adjusted and weighed, and 3.168 g of ascorbic acid was dissolved in the ammonia water (the concentration of ascorbic acid was 100 mmol / L) to form a mixed solution B. The calcined cylindrical intermediates were immersed in the mixed solution B, with a solid to liquid mass ratio of 1:6, followed by hydrothermal reaction at 130°C for 10 h, and then washed and dried to obtain the product.

[0035] Gas chromatography detection results:

[0036]

[0037] Example 2

[0038] Synthesis of sample: 5.7191 g CuCl2 2H2O and 0.5215 g PdCl2 were weighed and dissolved in 10 ml deionized water to form a mixed solution A. 30 g of 8000 mesh hydrophilic fumed silica (Guangzhou Yikai Chemical Technology Co., Ltd., Cabot TS720 type, USA) and 1.2 g of Tianjing powder were weighed and mixed uniformly. The mixed solution A was poured into the mixed powder and kneaded repeatedly, with moderate water added to knead into a lump, and then extruded into a 3 mm clover intermediate. After complete drying at 80°C, it was transferred to a muffle furnace and calcined at 600°C for 3 h. 240 g of ammonia water with a pH value of 13 was adjusted and weighed, 6.336 g of ascorbic acid was dissolved in the ammonia water (the concentration of ascorbic acid was 150 mmol / L) to form a mixed solution B. The calcined clover intermediate was immersed in the mixed solution B, with a solid to liquid mass ratio of 1:8, followed by hydrothermal reaction at 140°C for 8 h, and then washed and dried to obtain the product.

[0039] Gas chromatography detection results:

[0040]

[0041] Example 3

[0042] Synthesis of sample: 5.7191 g CuCl2 2H2O and 0.5215 g PdCl2 were weighed and dissolved in 10 ml deionized water to form a mixed solution A. 30 g of 8000 mesh hydrophilic fumed silica (Guangzhou Yikai Chemical Technology Co., Ltd., Cabot TS720 type, USA) and 1.2 g of Tianjing powder were weighed and mixed uniformly. The mixed solution A was poured into the mixed powder and kneaded repeatedly, with moderate water added to knead into a lump, and then extruded into a 3 mm clover intermediate. After complete drying at 80°C, it was transferred to a muffle furnace and calcined at 600°C for 3 h. 240 g of ammonia water with a pH value of 13 was adjusted and weighed, 6.336 g of ascorbic acid was dissolved in the ammonia water (the concentration of ascorbic acid was 150 mmol / L) to form a mixed solution B. The calcined clover intermediate was immersed in the mixed solution B, with a solid to liquid mass ratio of 1:8, followed by hydrothermal reaction at 140°C for 8 h, and then washed and dried to obtain the product.

[0043] Gas chromatography detection results:

[0044]

[0045] Example 4

[0046] Synthesis of sample: 4.6468 g of CuCl2and 0.4346 g of PdCl2were weighed and dissolved in 10 ml of deionized water to form a mixed solution A. 30 g of 3000 mesh hydrophilic fumed silica (Guangzhou Yinnuo Chemical Technology Co., Ltd., Japan, QS102 type) and 0.9 g of Tianjing powder were weighed and mixed uniformly. The mixed solution A was poured into the mixed powder and kneaded repeatedly, and water was added moderately during the kneading until the kneaded mass was formed, and then extruded into 2 mm clover intermediates. After complete drying at 80°C, it was transferred to a muffle furnace and calcined at 550°C for 2 h. 300 g of ammonia water with a pH value of 14 was adjusted and weighed, and 12.560 g of ascorbic acid was dissolved in the ammonia water (the concentration of ascorbic acid was 200 mmol / L) to form a mixed solution B. The calcined clover intermediates were immersed in the mixed solution B, and the mass ratio of solid to liquid was 1:10, followed by hydrothermal reaction at 150°C for 12 h, and then washed and dried to obtain the product.

[0047] Gas chromatography detection results:

[0048]

[0049] Comparative example 1

[0050] Synthesis of sample: 5.7191 g of CuCl2·2H2O and 0.5215 g of PdCl2were weighed and dissolved in 10 ml of deionized water to form a mixed solution A. 30 g of 8000 mesh hydrophilic fumed silica (Guangzhou Yinnuo Chemical Technology Co., Ltd., USA, Cabot TS720 type) and 1.2 g of Tianjing powder were weighed and mixed uniformly. The mixed solution A was poured into the mixed powder and kneaded repeatedly, and water was added moderately during the kneading until the kneaded mass was formed, and then extruded into 3 mm clover intermediates. After complete drying at 80°C, it was transferred to a muffle furnace and calcined at 600°C for 3 h. 150 ml of 0.5M NaOH solution was prepared, and the calcined clover intermediates were immersed in the NaOH solution and stood for 1 h. Then it was washed repeatedly to neutral, dried and calcined at 400°C for 2 h to obtain the product.

[0051] Gas chromatography detection results:

[0052]

Claims

1. A process for the preparation of a bimetallic catalyst of copper and palladium for the catalytic synthesis of bismorpholine diethyl ether, characterized by: The catalyst is prepared by hydrothermal synthesis method, taking fumed silica as carrier, copper-palladium composite metal oxide as active component and ascorbic acid as structure directing agent; the mass percentage of cuprous oxide is 9-16% and the mass percentage of palladium oxide is 0.3-1.2% based on the mass of the carrier; The catalyst is prepared by the following method: (1) fumed silica is mixed with a binder, and a copper-palladium precursor mixture solution is prepared, then the two are mixed uniformly and extruded into a shape and dried; (2) the shaped mixture is calcined at 500-600℃ for 2-4h; (3) the pH value of ammonia water is adjusted to 12-14, ascorbic acid is dissolved in ammonia water as a structure directing agent, and then the calcined product is immersed in the ammonia water mixture solution for hydrothermal reaction; the mass ratio of the calcined product to the ammonia water mixture solution in the hydrothermal reaction is 1:6-10; (4) the product after hydrothermal reaction is collected, washed and dried to obtain the finished catalyst.

2. The method of claim 1, wherein: The fumed silica in step (1) is hydrophilic fumed silica with a particle size of 1000-8000 mesh.

3. The method of claim 1, wherein: The binder in step (1) is Tianqian powder, polyethylene oxide (PEO) or sodium carboxymethyl cellulose (CMC), and the mass percentage of the binder is 3-5% based on the mass of the carrier.

4. The method of claim 1, wherein: The copper-palladium precursor in step (1) is a chloride salt of copper and palladium.

5. The method of claim 1, wherein: The extrusion molding shape in step (1) is columnar, trilobal or quadrilobal.

6. The method of claim 1, wherein: The calcination temperature in step (2) is 500-600℃, the calcination time is 2-4h, and the calcination environment is air atmosphere.

7. The method of claim 1, wherein: In step (3), ascorbic acid is dissolved in ammonia water to form a mixed solution with an ascorbic acid concentration of 100-200 mmol / L.

8. The method of claim 1, wherein: The temperature of the hydrothermal reaction is 130-150℃, and the time of the hydrothermal reaction is 8-12h.

9. The application of the copper-palladium bimetallic catalyst of claim 1 in catalyzing the synthesis of bis-morpholine diethyl ether.

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