A Cu-based organic hybrid material, a preparation method thereof and application thereof in catalytic preparation of acetaldehyde

Abstract

The application discloses a Cu-based organic hybrid material and a preparation method thereof. The Cu-based organic hybrid material is prepared from the following raw materials: a soluble copper salt precursor, a polybasic acid or a polyaldehyde, a polyamine and an alcohol solution; wherein the ratio of copper ions in the soluble copper salt precursor to the alcohol solution is 0.02-0.4 mol:1L, and the ratio of the total moles of the polybasic acid or the polyaldehyde and the polyamine to the alcohol solution is 1-1.25 mol:1L. Meanwhile, the application also discloses application of the Cu-based organic hybrid material in catalyzing ethanol dehydrogenation to prepare acetaldehyde. The Cu-based organic hybrid material has the advantages of high reaction activity and good stability in the ethanol catalytic dehydrogenation reaction, and has no obvious deactivation phenomenon after being used for a long time of 200 hours.

Description

Technical Field

[0001] This invention belongs to the field of acetaldehyde preparation technology, specifically relating to a Cu-based organic hybrid material, its preparation method, and its application in the catalytic preparation of acetaldehyde. Background Technology

[0002] Acetaldehyde, as a direct derivative of ethanol, has a very broad market for chemical applications, with an existing demand of approximately 300,000 to 400,000 tons as an upstream raw material. This includes approximately 200,000 tons from the pentaerythritol industry, 100,000 tons from pyridine and its derivatives, 80,000 tons from the nicotinic acid industry, 150,000 tons from crotonaldehyde and vanillin production, and approximately 80,000 tons from 1,3-butanediol and other bactericides and preservatives. Furthermore, it is expected to serve as a monomer for biodegradable materials such as lactic acid and methyl hydroxybutyrate. Therefore, acetaldehyde is a chemical product with significant potential.

[0003] Currently, there are two routes for producing acetaldehyde from ethanol. One is the ethanol oxidation method, in which ethanol vapor is mixed with air on a silver wire mesh or expanded silver catalyst, and an oxidation reaction occurs under high temperature and pressure. The single-pass conversion rate of ethanol reaches 30%-50%, with a selectivity of 85%-95%. However, producing 1 ton of acetaldehyde generates 5-10 tons of highly toxic aldehyde-containing wastewater. Due to high safety and environmental costs, small-scale ethanol oxidation plants in China are currently mostly shut down. The second process is the ethanol oxygen-free catalytic dehydrogenation method. This route has attracted much research attention due to its advantages such as simple production process, low equipment investment, and intrinsic safety. Existing literature and patents have reported on this process. Among them, catalysts without Cu, such as ZnAl2O4, ZnO / SiO2, Co / SBA-15, and H1-xTi2(PO4)3-x(SO4)x, have high activity but poor selectivity for acetaldehyde. NiAu alloy / SiO2 catalyst has good activity and selectivity, but it is expensive, has a short lifespan, and uses helium as a dilution gas, which causes problems for subsequent hydrogen utilization and is not suitable for industrial application. For Cu-containing catalysts, high conversion rate and long catalyst lifetime present a seesaw-like contradiction. High temperature is beneficial for improving ethanol conversion rate, but Cu is more sensitive to temperature than other metals, gradually undergoing thermal migration and aggregation, leading to sintering deactivation. For example, the catalysts disclosed in CN105148911A and CN103127945A, while showing satisfactory reactivity and selectivity for acetaldehyde, have received virtually no reports on lifetime or have very short lifetimes (within 200 hours). Chinese patent CN106673977A discloses a catalyst for the direct dehydrogenation of ethanol to acetaldehyde. This catalyst uses Cu as the active component and a carbon-coated oxide composite as a support. The active component Cu is loaded onto the support via impregnation. Due to the improved catalyst framework structure of the composite support, the ethanol conversion rate is 75% and the acetaldehyde selectivity is approximately 92% at 260°C. However, there are no experimental reports on the long-term stability of the catalyst. Therefore, developing highly active and long-life catalytic dehydrogenation catalysts is of significant practical importance for the ethanol-to-acetaldehyde process. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a Cu-based organic hybrid material, its preparation method, and its application in the catalytic preparation of acetaldehyde. The Cu-based organic hybrid material exhibits advantages such as high reactivity and good stability in the ethanol dehydrogenation reaction.

[0005] A Cu-based organic hybrid material is prepared from the following raw materials: a soluble copper salt precursor, a polybasic acid or polybasic aldehyde, a polybasic amine, and an alcohol solution; wherein the ratio of copper ions in the soluble copper salt precursor to the alcohol solution is 0.02-0.4 mol:1 L, and the ratio of the total moles of the polybasic acid or polybasic aldehyde and the polybasic amine to the alcohol solution is 1-1.25 mol:1 L.

[0006] Preferably, the molar ratio of the polyacid or polyaldehyde to the polyamine is 1-1.5:1.

[0007] Preferably, the polybasic acid is terephthalic acid, isophthalic acid, or pyromellitic acid.

[0008] Preferably, the polyaldehyde is terephthalaldehyde or 2,5-furandialdehyde.

[0009] Preferably, the polyamine is p-phenylenediamine or melamine.

[0010] Preferably, the soluble copper salt precursor is copper nitrate, copper acetate, or copper chloride; and the alcohol solution is methanol or ethanol.

[0011] The Cu-based organic hybrid material is prepared using a sol-gel one-pot method, and the specific preparation method is as follows:

[0012] (1) Dissolve the soluble copper salt precursor, polybasic acid or polybasic aldehyde or polybasic amine in an alcohol solution, stir, and obtain a mixed solution;

[0013] (2) Seal the mixed solution and perform hydrothermal treatment at 100-150℃ for 10-24 hours. After cooling, filter and wash the solution and dry it under an inert atmosphere.

[0014] Preferably, the drying conditions are drying at 100-300℃ for 5-12 hours.

[0015] Preferably, the washing is performed using an alcohol solution, and the volume of the alcohol solution used for washing is 2-3 times that of the alcohol solution in the raw material.

[0016] The application of the Cu-based organic hybrid material in the catalytic preparation of acetaldehyde, specifically the application of ethanol dehydrogenation to prepare acetaldehyde.

[0017] Preferably, the application specifically involves: loading the Cu-based organic hybrid material into a fixed-bed reactor, introducing ethanol, and reacting at 200-300°C, wherein the ethanol space velocity is 0.1-5 h⁻¹. -1 More preferably, the reaction is carried out at 210-280°C, and the space velocity of the ethanol is 0.5-3 h⁻¹. -1 .

[0018] More preferably, the reaction is carried out at 230°C, 250°C or 270°C.

[0019] More preferably, the space velocity of the ethanol is 1 h⁻¹. -1 1.5h -1 2h -1 Or 2.5h -1 .

[0020] This invention utilizes a sol-gel one-pot method, employing inorganic salts of Cu, polybasic acids / aldehydes, and polyamine compounds for hydrothermal treatment to ultimately obtain the material. The specific reaction processes are illustrated below, using the reactions of terephthalic acid with p-phenylenediamine and terephthalaldehyde with p-phenylenediamine as examples:

[0021] ,

[0022]

[0023] , where n is a natural number excluding 0;

[0024] Other polybasic acids react with polybasic amines and polybasic aldehydes react with polybasic amines in a similar way to form highly cross-linked organic compounds. The Cu ions added to these compounds form coordination relationships with the carboxyl and amino groups in the organic compounds and are highly uniformly dispersed within them. After heat treatment, Cu-based organic hybrid materials are finally formed.

[0025] Advantages of this invention:

[0026] (1) The Cu-based organic hybrid material finally prepared by the present invention is composed of highly cross-linked network organic matter and Cu ions encapsulated therein. The material has the characteristics of abundant pores, small particle size, uniform particle size, large specific surface area, and highly dispersed Cu species.

[0027] (2) The Cu-based organic hybrid material has the advantages of high reactivity and good stability in the catalytic dehydrogenation reaction of ethanol, and there is no obvious deactivation phenomenon after 200 hours of long-term use. Detailed Implementation

[0028] Example 1

[0029] A Cu-based organic hybrid material is prepared from the following raw materials: 0.4 mmol copper nitrate, 10 mmol terephthalic acid, 10 mmol melamine and 20 mL ethanol;

[0030] The Cu-based organic hybrid material was prepared by the following method:

[0031] (1) Copper nitrate, terephthalic acid, and melamine are dissolved in ethanol and stirred to obtain a mixed solution;

[0032] (2) The mixed solution is placed in a hydrothermal reactor and sealed. It is hydrothermally treated at 100°C for 10 hours. After cooling, the obtained slurry is filtered, washed with 40 mL of ethanol, and dried at 100°C for 5 hours in a N2 atmosphere to obtain the Cu organic hybrid material, denoted as Cat-1.

[0033] Example 2

[0034] Take 2.0 mmol of copper nitrate, and follow the same procedure as in Example 1. The resulting Cu organic hybrid material is denoted as Cat-2.

[0035] Example 3

[0036] Take 4.0 mmol of copper nitrate, and follow the same procedure as in Example 1. The resulting Cu organic hybrid material is denoted as Cat-3.

[0037] Example 4

[0038] Take 6.0 mmol of copper nitrate, and follow the same procedure as in Example 1. The resulting Cu organic hybrid material is denoted as Cat-4.

[0039] Example 5

[0040] Take 8.0 mmol of copper nitrate, and follow the same procedure as in Example 1. The resulting Cu organic hybrid material is denoted as Cat-5.

[0041] Example 6

[0042] A Cu-based organic hybrid material is prepared from the following raw materials: 4.0 mmol copper acetate, 12 mmol isophthalic acid, 10 mmol p-phenylenediamine and 20 mL methanol;

[0043] The Cu-based organic hybrid material was prepared by the following method:

[0044] (1) Copper acetate, isophthalic acid, and p-phenylenediamine are dissolved in methanol and stirred to obtain a mixed solution;

[0045] (2) The mixed solution is placed in a hydrothermal reactor and sealed. It is hydrothermally treated at 130°C for 24 hours. After cooling, the obtained slurry is filtered, washed with 60 mL of methanol, and dried at 200°C for 12 hours in a N2 atmosphere to obtain the Cu organic hybrid material, denoted as Cat-6.

[0046] Example 7

[0047] A Cu-based organic hybrid material is prepared from the following raw materials: 4.0 mmol copper chloride, 12 mmol trimesic acid, 10 mmol melamine and 20 mL ethanol;

[0048] The Cu-based organic hybrid material was prepared by the following method:

[0049] (1) Copper chloride, pyromellitic acid and melamine are dissolved in ethanol and stirred to obtain a mixed solution;

[0050] (2) The mixed solution is placed in a hydrothermal reactor and sealed. It is hydrothermally treated at 150°C for 18 hours. After cooling, the obtained slurry is filtered, washed with 60 mL of ethanol, and dried at 300°C for 6 hours in a N2 atmosphere to obtain the Cu organic hybrid material, denoted as Cat-7.

[0051] Example 8

[0052] A Cu-based organic hybrid material is prepared from the following raw materials: 5.0 mmol copper nitrate, 15 mmol terephthalic acid, 10 mmol melamine and 20 mL methanol;

[0053] The Cu-based organic hybrid material was prepared by the following method:

[0054] (1) Copper nitrate, terephthalic acid, and melamine are dissolved in methanol and stirred to obtain a mixed solution;

[0055] (2) The mixed solution is placed in a hydrothermal reactor and sealed. It is hydrothermally treated at 100°C for 10 hours. After cooling, the obtained slurry is filtered, washed with 40 mL of methanol, and dried at 200°C for 5 hours in a N2 atmosphere to obtain the Cu organic hybrid material, denoted as Cat-8.

[0056] Example 9

[0057] A Cu-based organic hybrid material is prepared from the following raw materials: 5.0 mmol copper nitrate, 13 mmol terephthalaldehyde, 10 mmol p-phenylenediamine and 20 mL ethanol;

[0058] The Cu-based organic hybrid material was prepared by the following method:

[0059] (1) Copper nitrate, terephthalaldehyde, and p-phenylenediamine are dissolved in ethanol and stirred to obtain a mixed solution;

[0060] (2) The mixed solution is placed in a hydrothermal reactor and sealed. It is hydrothermally treated at 100°C for 10 hours. After cooling, the obtained slurry is filtered, washed with 40 mL of ethanol, and dried at 100°C for 5 hours in a N2 atmosphere to obtain the Cu organic hybrid material, denoted as Cat-9.

[0061] Example 10

[0062] A Cu-based organic hybrid material is prepared from the following raw materials: 5.0 mmol copper nitrate, 13 mmol 2,5-furandicarboxaldehyde, 10 mmol p-phenylenediamine and 20 mL ethanol;

[0063] The Cu-based organic hybrid material was prepared by the following method:

[0064] (1) Copper nitrate, 2,5-furandicarboxaldehyde, and p-phenylenediamine are dissolved in ethanol and stirred to obtain a mixed solution;

[0065] (2) The mixed solution is placed in a hydrothermal reactor and sealed. It is hydrothermally treated at 100°C for 10 hours. After cooling, the obtained slurry is filtered, washed with 40 mL of ethanol, and dried at 100°C for 5 hours in a N2 atmosphere to obtain the Cu organic hybrid material, denoted as Cat-10.

[0066] Catalytic performance testing

[0067] 1. The Cu-based organic hybrid material is used in the reaction for the dehydrogenation of ethanol to prepare acetaldehyde, specifically as follows: the Cu-based organic hybrid material is packed into a fixed-bed reactor, ethanol is introduced, and the reaction is carried out at 250°C, with an ethanol space velocity of 1.5 h⁻¹. -1 The conversion rate of ethanol and the selectivity of acetaldehyde were measured after 60 h of reaction, and the results are shown in Table 1.

[0068] Table 1. Reaction results of Cu-based organic hybrid materials in Examples 1-10

[0069] Application examples Cu-based organic hybrid materials Ethanol conversion rate Acetaldehyde selectivity Application Example 1 Cat-1 21.9% 92.5% Application Example 2 Cat-2 24.5% 91.5% Application Example 3 Cat-3 28.6% 92.4% Application Example 4 Cat-4 30.3% 93.1% Application Example 5 Cat-5 34.1% 90.3% Application Example 6 Cat-6 23.9% 93.5% Application Example 7 Cat-7 32.5% 91.5% Application Example 8 Cat-8 31.6% 92.4% Application Example 9 Cat-9 25.3% 95.1% Application Example 10 Cat-10 34.6% 92.8%

[0070] As shown in Table 1, the catalyst provided by this invention has high reactivity and high selectivity for acetaldehyde in the catalytic dehydrogenation of ethanol to acetaldehyde.

[0071] 2. The Cu-based organic hybrid material provided in Example 4 was packed into a fixed-bed reactor, and ethanol was introduced. The reaction to prepare acetaldehyde by ethanol dehydrogenation was carried out at different reaction temperatures and ethanol mass hourly space velocities. The performance of the reaction was tested after 200 h, and the results are shown in Table 2.

[0072] Table 2. Reaction results of Cu-based organic hybrid materials under different reaction conditions in Example 4.

[0073] .

Claims

1. Use of a Cu-based organic hybrid material in the catalytic dehydrogenation of ethanol to acetaldehyde, characterized in that: The Cu-based organic hybrid material is prepared from the following raw materials: a soluble copper salt precursor, a polybasic acid or a polyaldehyde, a polyamine and an alcohol solution; wherein the ratio of copper ions in the soluble copper salt precursor to the alcohol solution is 0.02-0.4 mol:1L, and the ratio of the total moles of the polybasic acid or the polyaldehyde and the polyamine to the alcohol solution is 1-1.25 mol:1L; The polybasic acid is terephthalic acid, isophthalic acid or trimesic acid; the polyaldehyde is terephthaldehyde or 2,5-furandicarboxaldehyde; and the polyamine is p-phenylenediamine or melamine. The Cu-based organic hybrid material is prepared by a sol-gel one-pot method, and the specific preparation method is as follows: (1) the soluble copper salt precursor, the polybasic acid or the polyaldehyde, and the polyamine are dissolved in the alcohol solution, and stirred to obtain a mixed solution; (2) the mixed solution is sealed and hydrothermally treated at 100-150℃ for 10-24h, and then filtered, washed and dried in an inert atmosphere. 2.The application of Cu-based organic hybrid material in catalyzing the preparation of acetaldehyde by dehydrogenation of ethanol according to claim 1, characterized in that: The molar ratio of the polybasic acid or the polyaldehyde to the polyamine is 1-1.5:

1.

3. The use of the Cu-based organic hybrid material according to claim 2 in the catalytic dehydrogenation of ethanol to acetaldehyde, characterized in that: The soluble copper salt precursor is copper nitrate, copper acetate or copper chloride; and the alcohol solution is methanol or ethanol.

4. The use of the Cu-based organic hybrid material according to any one of claims 1-3 for the catalytic dehydrogenation of ethanol to acetaldehyde, characterized in that: The drying condition is baking and drying at 100-300℃ for 5-12h.

5. The use of the Cu-based organic hybrid material according to claim 1 in the catalytic dehydrogenation of ethanol to acetaldehyde, characterized in that: The Cu-based organic hybrid material is loaded into a fixed bed reactor, ethanol is passed in, and the reaction is carried out at 200-300°C, the space velocity of the ethanol being 0.1-5 h -1 .

6. The use of the Cu-based organic hybrid material according to claim 5 for the catalytic dehydrogenation of ethanol to acetaldehyde, characterized in that: The reaction is carried out at 210-280°C at an ethanol space velocity of 0.5-3 h -1 .

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