A catalyst for preparing acetaldehyde and ethyl acetate by ethanol dehydrogenation, a preparation method and application thereof

Abstract

The application discloses a preparation method of a catalyst for preparing acetaldehyde and ethyl acetate in ethanol dehydrogenation, characterized in that the catalyst is prepared by loading Cu and Ag on a carrier of attapulgite; the preparation method is as follows: the attapulgite is subjected to acid treatment, then is subjected to ion exchange with a copper salt solution to load Cu, and then is subjected to an impregnation method to load Ag, and then is dried and calcined. Meanwhile, the application also discloses application of the catalyst in preparation of acetaldehyde and ethyl acetate in ethanol dehydrogenation. The catalyst provided by the application has good catalytic activity and stability, and can realize continuous dehydrogenation of ethanol to prepare acetaldehyde and ethyl acetate in a fixed bed continuous reactor, so that the process is simple, energy consumption is low, and the catalyst has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of acetaldehyde preparation technology, specifically relating to a catalyst for the dehydrogenation of ethanol to prepare acetaldehyde and co-production of ethyl acetate, its preparation method and application. Background Technology

[0002] With the development and maturation of coal-to-ethanol technology, a large number of coal-to-ethanol plants have begun production, inevitably bringing a sufficient supply of low-cost ethanol feedstock. Converting ethanol into high-value-added chemical products is an effective means to improve ethanol utilization and corporate profits. Acetaldehyde, as an important downstream bulk product of ethanol, has a global market demand exceeding 2 million tons. It can be used not only to prepare traditional products such as pentaerythritol and alkyd resins, but also in pharmaceutical and pesticide fine chemical products such as crotonaldehyde, B vitamins, and sorbitol. Ethyl acetate is one of the most widely used fatty acid esters, a fast-drying solvent with excellent dissolving power, making it an excellent industrial solvent. It can be used in nitrocellulose, ethylcellulose, chlorinated rubber and ethylene resins, cellulose acetate esters, cellulose butyl acetate and synthetic rubber, and also in liquid nitrocellulose inks for copiers. It can be used as a solvent for adhesives, a thinner for paints; in the textile industry, it can be used as a cleaning agent; in the food industry, it can be used as a flavor extractant for special modified alcohols; and it is also used in pharmaceutical processes and as an extractant for organic acids. In the fragrance industry, it is an important fragrance additive and can be used as a component of flavoring agents.

[0003] Currently, the main process for producing acetaldehyde from ethanol is the ethanol oxidation method. This method generates a large amount of toxic aldehyde-containing wastewater, posing a significant environmental burden. Existing research reports on the direct dehydrogenation method suffers from poor stability due to the tendency of Cu catalysts to aggregate at high temperatures, leading to deactivation. Meanwhile, the industrial production of ethyl acetate in China primarily employs the esterification method, often using corrosive sulfuric acid as a catalyst. Because the esterification reaction is reversible, the conversion rate is only about 67%. To increase the conversion rate, excess ethanol is generally used, and water generated during the reaction is continuously separated. Considering the current requirements for green, environmentally friendly, low-energy-consumption, and low-production-cost chemical production, developing a highly efficient catalyst for the co-production of ethyl acetate from ethanol dehydrogenation to acetaldehyde is not only significant for the development of fine chemicals but also plays a crucial role in the healthy development of the coal-to-ethanol industry. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a catalyst for the dehydrogenation of ethanol to produce acetaldehyde and ethyl acetate, and its preparation method. Attapulgite is used as a support, and metals Cu and Ag are loaded onto the support via ion exchange and impregnation. Furthermore, the invention provides the application of the catalyst in the dehydrogenation of ethanol to produce acetaldehyde and ethyl acetate, wherein the ratio of acetaldehyde to ethyl acetate is adjusted by regulating the Cu / Ag ratio.

[0005] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite, with Cu and Ag loaded on the support; the preparation method is as follows: attapulgite is acid-treated, then Cu is loaded by ion exchange with a copper salt solution, Ag is loaded by impregnation, and then dried and calcined.

[0006] Preferably, the preparation method is as follows:

[0007] (1) Add attapulgite to nitric acid solution, stir for 3-6 hours, filter and wash with water until neutral;

[0008] (2) The solid obtained in step (1) is subjected to ion exchange with copper nitrate solution or copper acetate solution, stirred for 5-10 hours, filtered and washed with water until colorless, and dried.

[0009] (3) The solid obtained in step (2) is impregnated with an equal volume of aqueous solution of soluble silver salt for 3-6 hours, dried, and calcined to obtain the catalyst.

[0010] Preferably, the mass concentration of the nitric acid solution is 5-10%, and the ratio of attapulgite to nitric acid solution is (10-20) g: 100 mL.

[0011] Preferably, the concentration of the copper nitrate solution or copper acetate solution is 0.02-0.2 mol / L, and the mass ratio of the attapulgite to the copper nitrate solution or copper acetate solution is 1:(10-20).

[0012] Preferably, the soluble silver salt is silver nitrate or silver acetate, and the molar ratio of Cu to Ag is (4.5-20):1.

[0013] Preferably, the drying conditions in step (2) are drying at 80-120℃ for 5-10 hours, the drying conditions in step (3) are drying at 80-120℃ for 3-5 hours, and the calcination conditions are calcination at 300-600℃ in air for 3-6 hours.

[0014] A catalyst for the dehydrogenation of ethanol to produce acetaldehyde and ethyl acetate is prepared by the above-described method.

[0015] Application of the catalyst in the dehydrogenation of ethanol to produce acetaldehyde and ethyl acetate.

[0016] Preferably, the application is as follows: the catalyst is loaded into a fixed-bed reactor, heated to 230-300°C, ethanol is introduced, and the reaction is carried out continuously under normal pressure.

[0017] Preferably, the mass hourly space velocity (MSV) of the ethanol is 0.5-5 h⁻¹. -1 .

[0018] Advantages of this invention:

[0019] (1) The catalyst provided by this invention has high stability. Due to the isomorphous substitution phenomenon in attapulgite (also known as palygorskite, abbreviated as Pal), the octahedral cations in Pal can be dissolved by acid treatment, and the remaining tetrahedral silicon retains the crystal framework of Pal, while the transition metal Cu... 2+ Ion exchange can restore the Pal structure through lattice reconstruction, forming a dioctahedral or di / trioctahedral transitional structure, resulting in Pal structures with different physicochemical properties. Due to Cu... 2+ The presence of Cu in the Pal crystal and its combination with the framework O results in a higher Cu content in the catalyst. 2+ Furthermore, it is highly dispersed and exhibits better stability compared to Cu catalysts prepared by conventional impregnation and adsorption methods;

[0020] (2) Active metal Ag can work synergistically with Cu to improve ethanol conversion rate, achieve deep dehydrogenation of ethanol and generate ethyl acetate; at the same time, by adjusting the CuAg metal ratio, selective control of acetaldehyde and ethyl acetate can be achieved, resulting in high catalytic activity.

[0021] (3) The catalyst provided by the present invention can realize the continuous dehydrogenation of ethanol to produce two high value-added products, acetaldehyde and ethyl acetate, in a fixed-bed continuous reactor. The process is simple, energy consumption is low, and it has broad application prospects. Implementation

[0022] Example 1

[0023] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0024] (1) Add 10g of attapulgite to 100mL of 8.0 wt% nitric acid solution, stir for 5h, filter and wash with water until neutral;

[0025] (2) The solid obtained in step (1) was added to 100 mL of 0.02 mol / L copper nitrate solution for ion exchange, stirred for 10 h, filtered and washed with water until colorless, and dried at 100 °C for 10 h.

[0026] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 0.2 mmol silver nitrate for 6 h, dried at 100°C for 3 h, and calcined in air at 400°C for 5 h to obtain the catalyst, which is denoted as catalyst CAT-1.

[0027] Example 2

[0028] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0029] (1) Add 10g of attapulgite to 100mL of 8.0 wt% nitric acid solution, stir for 5h, filter and wash with water until neutral;

[0030] (2) The solid obtained in step (1) was added to 100 mL of 0.08 mol / L copper nitrate solution for ion exchange, stirred for 10 h, filtered and washed with water until colorless, and dried at 100 °C for 10 h.

[0031] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 0.8 mmol silver nitrate for 6 h, dried at 100°C for 3 h, and calcined in air at 400°C for 5 h to obtain the catalyst, which is denoted as catalyst CAT-2.

[0032] Example 3

[0033] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0034] (1) Add 10g of attapulgite to 100mL of 8.0 wt% nitric acid solution, stir for 5h, filter and wash with water until neutral;

[0035] (2) The solid obtained in step (1) was added to 100 mL of 0.12 mol / L copper nitrate solution for ion exchange, stirred for 10 h, filtered and washed with water until colorless, and dried at 100 °C for 10 h.

[0036] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 1.2 mmol silver nitrate for 6 h, dried at 100°C for 3 h, and calcined in air at 400°C for 5 h to obtain the catalyst, which is denoted as catalyst CAT-3.

[0037] Example 4

[0038] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0039] (1) Add 10g of attapulgite to 100mL of 8.0 wt% nitric acid solution, stir for 5h, filter and wash with water until neutral;

[0040] (2) The solid obtained in step (1) was added to 100 mL of 0.16 mol / L copper nitrate solution for ion exchange, stirred for 10 h, filtered and washed with water until colorless, and dried at 100 °C for 10 h.

[0041] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 1.6 mmol silver nitrate for 6 h, dried at 100°C for 3 h, and calcined in air at 400°C for 5 h to obtain the catalyst, which is denoted as catalyst CAT-4.

[0042] Example 5

[0043] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0044] (1) Add 10g of attapulgite to 100mL of 8.0 wt% nitric acid solution, stir for 5h, filter and wash with water until neutral;

[0045] (2) The solid obtained in step (1) was added to 100 mL of 0.2 mol / L copper nitrate solution for ion exchange, stirred for 10 h, filtered and washed with water until colorless, and dried at 100 °C for 10 h.

[0046] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 2.0 mmol silver nitrate for 6 h, dried at 100°C for 3 h, and calcined in air at 400°C for 5 h to obtain the catalyst, which is denoted as catalyst CAT-5.

[0047] Example 6

[0048] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0049] (1) Add 10g of attapulgite to 100mL of 8.0 wt% nitric acid solution, stir for 3h, filter and wash with water until neutral;

[0050] (2) The solid obtained in step (1) was added to 100 mL of 0.12 mol / L copper nitrate solution for ion exchange, stirred for 5 h, filtered and washed with water until colorless, and dried at 100 °C for 5 h.

[0051] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 0.6 mmol silver nitrate for 3 h, dried at 80 °C for 5 h, and calcined in air at 300 °C for 6 h to obtain the catalyst, which is denoted as catalyst CAT-6.

[0052] Example 7

[0053] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0054] (1) Add 10g of attapulgite to 100mL of 8.0 wt% nitric acid solution, stir for 3h, filter and wash with water until neutral;

[0055] (2) The solid obtained in step (1) was added to 100 mL of 0.12 mol / L copper nitrate solution for ion exchange, stirred for 5 h, filtered and washed with water until colorless, and dried at 100 °C for 5 h.

[0056] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 2.4 mmol silver nitrate for 3 h, dried at 80 °C for 5 h, and calcined in air at 300 °C for 6 h to obtain the catalyst, which is denoted as catalyst CAT-7.

[0057] Example 8

[0058] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0059] (1) Add 10g of attapulgite to 100mL of 8.0 wt% nitric acid solution, stir for 3h, filter and wash with water until neutral;

[0060] (2) The solid obtained in step (1) was added to 100 mL of 0.12 mol / L copper nitrate solution for ion exchange, stirred for 5 h, filtered and washed with water until colorless, and dried at 100 °C for 5 h.

[0061] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 1.2 mmol silver nitrate for 3 h, dried at 80 °C for 5 h, and calcined in air at 300 °C for 6 h to obtain the catalyst, which is denoted as catalyst CAT-8.

[0062] Example 9

[0063] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0064] (1) Add 10g of attapulgite to 50mL of 8.0 wt% nitric acid solution, stir for 6h, filter and wash with water until neutral;

[0065] (2) The solid obtained in step (1) was added to 150 mL of 0.12 mol / L copper nitrate solution for ion exchange, stirred for 8 h, filtered and washed with water until colorless, and dried at 120 °C for 8 h.

[0066] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 4.0 mmol silver nitrate for 5 h, dried at 120°C for 5 h, and calcined in air at 600°C for 3 h to obtain the catalyst, which is denoted as catalyst CAT-9.

[0067] Example 10

[0068] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0069] (1) Add 10g of attapulgite to 50mL of 8.0 wt% nitric acid solution, stir for 6h, filter and wash with water until neutral;

[0070] (2) The solid obtained in step (1) was added to 200 mL of 0.12 mol / L copper nitrate solution for ion exchange, stirred for 8 h, filtered and washed with water until colorless, and dried at 120 °C for 8 h.

[0071] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 2.0 mmol silver nitrate for 5 h, dried at 120°C for 5 h, and calcined in air at 600°C for 3 h to obtain the catalyst, which is denoted as catalyst CAT-10.

[0072] Comparative Example 1

[0073] Cu was loaded onto the attapulgite support using a loading method rather than an ion exchange method. Other details are the same as in Example 1, as follows:

[0074] A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate, wherein the catalyst is supported on attapulgite with Cu and Ag loaded on the support; the preparation method is as follows:

[0075] (1) Add 10g of attapulgite to 100mL of 0.02mol / L copper nitrate solution and stir for 10h;

[0076] (2) The product of step (1) was evaporated at 70°C to remove water, and the resulting solid was dried at 100°C for 10 hours.

[0077] (3) The solid obtained in step (2) is impregnated with an equal volume of silver nitrate aqueous solution containing 0.2 mmol silver nitrate for 6 h, dried at 100°C for 3 h, and calcined in air at 400°C for 5 h to obtain the catalyst, which is denoted as catalyst CAT-D1.

[0078] I. Catalytic performance testing

[0079] 1 g of each of the catalysts prepared above was packed into a fixed-bed reactor with a reaction tube diameter of 10 mm. The temperature was raised to the reaction temperature, and ethanol was injected at a certain flow rate through a high-pressure constant flow pump. The reaction solution was tested by gas chromatography. The results were obtained after 24 hours of stable operation, as shown in Table 1.

[0080] Table 1. Catalytic performance test results

[0081]

[0082] II. Stability Testing

[0083] The catalysts CAT-1 and CAT-D1 were reacted under the reaction conditions of the CAT-1 catalyst described above, and the catalytic efficiency at different reaction times was measured to detect the stability of the catalysts, as detailed in Table 2.

[0084] Table 2 Catalytic results at different times

[0085] .

Claims

1. A method for preparing a catalyst for the dehydrogenation of ethanol to acetaldehyde co-producing ethyl acetate, characterized by: The catalyst is attapulgite as a carrier, Cu and Ag loaded on the carrier; the preparation method is as follows: the attapulgite is subjected to acid treatment, then Cu is loaded by ion exchange with a copper salt solution, Ag is loaded by impregnation, and then drying and calcination are performed; the molar ratio of Cu to Ag is (4.5-20):

1.

2. The method for preparing the catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate according to claim 1, characterized in that: The preparation method is specifically as follows: (1) the attapulgite is added into a nitric acid solution, stirred for 3-6 h, and then filtered and washed with water until neutral; (2) the solid obtained in step (1) is subjected to ion exchange with a copper nitrate solution or a copper acetate solution, stirred for 5-10 h, filtered and washed with water until colorless, and then dried; (3) the solid obtained in step (2) is subjected to equal-volume impregnation with an aqueous solution of a soluble silver salt for 3-6 h, dried, and then calcined to obtain the catalyst.

3. The method for preparing the catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate according to claim 2, characterized in that: The mass concentration of the nitric acid solution is 5-10%, and the ratio of the attapulgite to the nitric acid solution is (10-20) g:100 mL.

4. The method for preparing the catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate according to claim 3, characterized in that: The concentration of the copper nitrate solution or the copper acetate solution is 0.02-0.2 mol / L, and the mass ratio of the attapulgite to the copper nitrate solution or the copper acetate solution is 1:(10-20).

5. The method for preparing the catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate according to claim 4, characterized in that: The soluble silver salt is silver nitrate or silver acetate.

6. The method for preparing the catalyst for the dehydrogenation of ethanol to acetaldehyde and the co-production of ethyl acetate according to claim 5, characterized in that: In step (2), the drying condition is drying at 80-120 ℃ for 5-10 h, and in step (3), the drying condition is drying at 80-120 ℃ for 3-5 h, and the calcination condition is calcination at 300-600 ℃ in an air atmosphere for 3-6 h.

7. A catalyst for the production of acetaldehyde and ethyl acetate as by-products by ethanol dehydrogenation, characterized by comprising a metal oxide containing at least one element selected from the group consisting of Groups 1 to 17 of the periodic table. The catalyst is prepared by the preparation method of any one of claims 1-6.

8. The use of the catalyst of claim 7 in the preparation of acetaldehyde and co-production of ethyl acetate by dehydrogenation of ethanol.

9. Use of the catalyst according to claim 8 for the preparation of acetaldehyde and co-production of ethyl acetate by dehydrogenation of ethanol, characterized by: The use is specifically as follows: the catalyst is loaded into a fixed bed reactor, heated to 230-300 ℃, and then ethanol is introduced, and continuous reaction is performed at normal pressure.

10. Use of the catalyst according to claim 9 for the preparation of acetaldehyde and co-production of ethyl acetate by dehydrogenation of ethanol, characterized by: said ethanol has a mass space velocity of 0.5-5 h -1 .

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