Medium and low temperature cyclohexanol dehydrogenation catalyst to cyclohexanone and its preparation method

Abstract

This invention discloses a low-to-medium temperature cyclohexanol dehydrogenation catalyst for cyclohexanone and its preparation method. The catalyst uses organomontmorillonite as a support, and copper species are loaded onto the support using an impregnation method. The copper ion content is 1%–20% by mass of the catalyst, and 0.1%–2% of an additive is added. After washing, drying, and calcination, the organomontmorillonite-supported copper catalyst is obtained. The catalyst prepared by this invention has high specific surface area, high activity, and stability. Under relatively low reaction conditions and with low copper content, the catalyst still exhibits good cyclohexanol conversion and cyclohexanone selectivity. Furthermore, due to the low reaction temperature, the aggregation of the active components of the catalyst is not significant, resulting in good stability.

Description

Technical Field

[0001] This invention belongs to the field of catalysis technology, specifically relating to a medium- and low-temperature cyclohexanol dehydrogenation catalyst for the production of cyclohexanone and its preparation method. Background Technology

[0002] Cyclohexanone is an important organic chemical raw material and a key intermediate in the synthesis of caprolactam and adipic acid. Currently, it is mainly produced industrially through the oxidation and dehydrogenation of cyclohexanol. The dehydrogenation method is widely used in the industrial production of cyclohexanone due to its relatively low byproduct production, simple operation, high yield, and safe process. The key technology for cyclohexanol dehydrogenation is the development of high-performance catalysts.

[0003] Current research on catalysts for the dehydrogenation of cyclohexanol to cyclohexanone mainly focuses on transition metal catalysts, especially copper-based catalysts.

[0004] CN109331826A discloses a catalyst for the dehydrogenation of cyclohexanol to cyclohexanone, its preparation method and application. The catalyst comprises: a ZnAl2O4 support, CuO active components and ZnO active components, and a La2O3 promoter. By mass of the catalyst, the content of CuO is 10-15 wt%, the content of ZnO is 20-25 wt%, and the content of La2O3 promoter is 2-5 wt%.

[0005] CN111036230A discloses a catalyst for the dehydrogenation of cyclohexanol to cyclohexanone. The active components of the catalyst are Cu2O and ZnO, with MgO as the main support and additional support structure promoters. The mass percentage of Cu2O in the active components of the catalyst is 30%–40%, and the mass percentage of ZnO is 10%–15%. The mass percentage of MgO in the support is 40%–50%, and the mass percentage of the support structure promoter is 5%–10%.

[0006] CN114570373A discloses a copper-silicon catalyst for the dehydrogenation of cyclohexanol to prepare cyclohexanone. The catalyst comprises an active component, a composite support, and an auxiliary agent. The active component is copper oxide, with a content of 32-45% by mass percentage of the copper-silicon catalyst. The composite support is composed of silicon oxide and zirconium oxide, with a content of 45-70%. The auxiliary agent is any one of metal oxide and alkaline earth metal oxide, with a content of 1-5%.

[0007] CN112387288A discloses a medium-temperature cyclohexanol dehydrogenation catalyst, in which active components and active additives are deposited on a silica support. The active components include oxides of copper, zinc and calcium, and the active additives are oxides of manganese and / or lanthanum.

[0008] The aforementioned cyclohexanol dehydrogenation catalysts mostly use oxides or composite oxides as supports. They have a high content of active metal components, low utilization rate of active components, and low active specific surface area. At the same time, at high reaction temperatures, the active components of the catalyst are prone to agglomeration, leading to deactivation. Summary of the Invention

[0009] Purpose of the invention: The purpose of this invention is to address the shortcomings of existing technologies by providing a medium- and low-temperature cyclohexanol dehydrogenation catalyst for the production of cyclohexanone and its preparation method.

[0010] This invention uses organomontmorillonite as a support, and loads the active copper component onto the support using an impregnation method. The modified montmorillonite has increased interlayer spacing, significantly increasing the specific surface area of ​​the support, resulting in higher dispersion of the active component and a larger active specific surface area. Therefore, under relatively low reaction conditions and with low copper content, the catalyst still exhibits good cyclohexanol conversion and cyclohexanone selectivity. Furthermore, due to the low reaction temperature, the aggregation of the active component in the catalyst is not significant, resulting in good stability.

[0011] Technical solution: The objective of this invention is achieved through the following technical solution:

[0012] This invention provides a medium-low temperature cyclohexanol dehydrogenation catalyst for cyclohexanone production. The catalyst uses organomontmorillonite as a support, and copper species are loaded onto the support by an impregnation method. The copper ion content is 1% to 20% by mass percentage of the catalyst, and 0.1% to 2% of auxiliary agents are doped. After washing, drying, and calcination, the organomontmorillonite-supported copper catalyst is obtained.

[0013] Preferably, the carrier is purified sodium-based montmorillonite modified with an organic modifier. The modified montmorillonite has increased interlayer spacing, significantly increasing the specific surface area of ​​the carrier, resulting in higher dispersion of the active components and a larger active specific surface area.

[0014] Furthermore, the organic modifier is one of dodecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, or hexadecyltrimethylammonium chloride. Long-chain quaternary ammonium salts readily react with montmorillonite through ion exchange, entering the interlayer of montmorillonite and effectively increasing the interlayer spacing, thereby increasing the specific surface area of ​​the carrier.

[0015] Preferably, the auxiliary agent is one of sodium chloride, potassium chloride, or calcium chloride. The above-mentioned auxiliary agent can regulate the interaction between the active component and the carrier.

[0016] This invention also provides a method for preparing the above-mentioned low-temperature cyclohexanol dehydrogenation catalyst to cyclohexanone, comprising the following steps:

[0017] (1) Dissolve the purified sodium montmorillonite in water at 75-80℃, add an organic modifier, adjust the pH to 7-8, continue the reaction at the temperature for 2-3 hours, cool to room temperature, filter, wash, dry at 105-110℃ for 8-12 hours, grind and pulverize, and sieve to obtain the organic montmorillonite carrier.

[0018] (2) Take the organo-montmorillonite support obtained in step (1), add a mixture of copper salt solution and ethanol, stir at 50-60℃ for 5-7h; add the additive, continue to keep warm and stir for 5-7h, cool to room temperature, filter, wash, dry at 105-110℃ for 8-12h, and calcine at 200-300℃ in air atmosphere for 3-4h to obtain the organo-montmorillonite supported copper catalyst.

[0019] Preferably, in step (1), by weight, for every 50 parts of purified sodium montmorillonite, 1000 parts of deionized water and 5 to 20 parts of organic modifier are added.

[0020] Preferably, in step (2), by weight, 300 parts of copper salt solution and 100 parts of ethanol are added for every 10 parts of organomontmorillonite carrier.

[0021] This invention describes a medium-low temperature cyclohexanol dehydrogenation catalyst for cyclohexanone production, which is obtained by loading copper species and additives onto the surface of an organomontmorillonite support under mild conditions using an impregnation method, followed by washing, drying, and calcination. The catalyst exhibits high specific surface area, high activity, and stability.

[0022] Preferably, in step (2), the copper salt solution is one of copper nitrate solution, copper sulfate solution or copper chloride solution with a concentration of 0.01 to 0.3 mol / L.

[0023] Furthermore, the concentration of the copper salt solution is 0.05–0.25 mol / L.

[0024] Preferably, in step (1), the mesh size of the sieve is 200 mesh.

[0025] The present invention also provides the application of the above-mentioned catalyst in the dehydrogenation of cyclohexanol to cyclohexanone.

[0026] Beneficial effects:

[0027] The catalyst for the dehydrogenation of cyclohexanol to cyclohexanone prepared by this invention has a high specific surface area, exhibits the highest activity and cyclohexanone selectivity at a copper loading of about 10%, and also has high stability. Detailed Implementation

[0028] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0029] In this invention, preferably, the sodium-based montmorillonite is purified sodium-based montmorillonite. Purification of sodium-based montmorillonite refers to the purification of sodium-based montmorillonite by a hydrocyclone separation method. The parameters of the purified sodium-based montmorillonite include: cation exchange capacity 125-135 mmol / g, expansion capacity 90-100 mL / g, colloidal value >500 mL / (15 g), and montmorillonite content 90-95% by weight.

[0030] In a preferred embodiment and / or comparative example of the present invention, the purified sodium-based montmorillonite has the following parameters: cation exchange capacity 130 mmol / g, swelling capacity 94 mL / g, colloidal value >500 mL / (15 g), and montmorillonite content 92.5% by weight.

[0031] Additionally, it should be noted that the volume of the gel formed by mixing bentonite and water in a certain proportion and adding an appropriate amount of magnesium oxide is called the gel valence. It is expressed in milliliters as the volume of gel formed from 15 grams of sample.

[0032] In this invention, sodium-based montmorillonite was purchased from Beidou Qiming (Beijing) Energy Saving Technology Service Co., Ltd.

[0033] Example 1

[0034] Weigh 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water, stir and dissolve at 80℃, add 15 parts of tetradecyltrimethylammonium chloride, adjust the pH to 7.5 with hydrochloric acid, continue to maintain 80℃ water bath, react for 2 hours, cool to room temperature, filter, wash thoroughly with deionized water to remove chloride ions, dry in 105℃ oven for 8 hours, grind and pulverize, pass through a 200-mesh sieve to obtain organomontmorillonite carrier (hereinafter referred to as: organic soil).

[0035] Ten parts of organo-montmorillonite were weighed and added to a mixture of 300 parts of 0.06 mol / L copper nitrate solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. Then, 0.1 parts of sodium chloride were added, and the mixture was stirred in a water bath for another 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 250°C for 3 hours to obtain a copper catalyst supported on organo-montmorillonite. The active component, calculated as copper ions, accounted for approximately 5% of the catalyst by mass, and is designated as #1.

[0036] Example 2

[0037] Weigh 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water, stir and dissolve at 80℃, add 10 parts of tetradecyltrimethylammonium chloride, adjust the pH to 7.5 with hydrochloric acid, continue to maintain 80℃ water bath, react for 2 hours, cool to room temperature, filter, wash thoroughly with deionized water to remove chloride ions, dry in 105℃ oven for 8 hours, grind and pulverize, pass through a 200-mesh sieve to obtain organomontmorillonite carrier (hereinafter referred to as: organic soil).

[0038] Ten parts of organo-montmorillonite were weighed and added to a mixture of 300 parts of 0.12 mol / L copper nitrate solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. Then, 0.1 parts of potassium chloride were added, and the mixture was stirred in a water bath for another 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 250°C for 3 hours to obtain a copper catalyst supported on organo-montmorillonite. The active component, calculated as copper ions, accounted for approximately 10% of the catalyst by mass, and is designated as #2.

[0039] Example 3

[0040] Weigh 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water, stir and dissolve at 80℃, add 15 parts of tetradecyltrimethylammonium chloride, adjust the pH to 7.5 with hydrochloric acid, continue to maintain 80℃ water bath, react for 2 hours, cool to room temperature, filter, wash thoroughly with deionized water to remove chloride ions, dry in 105℃ oven for 8 hours, grind and pulverize, pass through a 200-mesh sieve to obtain organomontmorillonite carrier (hereinafter referred to as: organic soil).

[0041] Ten parts of organo-montmorillonite were weighed and added to a mixture of 300 parts of 0.18 mol / L copper sulfate solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. Then, 0.1 parts of potassium chloride were added, and the mixture was stirred in a water bath for another 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 260°C for 3 hours to obtain a copper catalyst supported on organo-montmorillonite. The active component, calculated as copper ions, accounted for approximately 15% of the catalyst by mass, and is designated as #3.

[0042] Example 4

[0043] Weigh 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water, stir and dissolve at 80℃, add 20 parts of tetradecyltrimethylammonium chloride, adjust the pH to 7.5 with hydrochloric acid, continue to maintain 80℃ water bath, react for 2 hours, cool to room temperature, filter, wash thoroughly with deionized water to remove chloride ions, dry in 105℃ oven for 8 hours, grind and pulverize, pass through a 200-mesh sieve to obtain organomontmorillonite carrier (hereinafter referred to as: organic soil).

[0044] Ten parts of organo-montmorillonite were weighed and added to a mixture of 300 parts of 0.24 mol / L copper nitrate solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. Then, 0.1 parts of potassium chloride were added, and the mixture was stirred in a water bath for another 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 240°C for 3 hours to obtain a copper catalyst supported on organo-montmorillonite. The active component, calculated as copper ions, accounted for approximately 20% of the catalyst by mass, and is designated as #4.

[0045] Example 5

[0046] Weigh 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water, stir and dissolve at 80℃, add 15 parts of tetradecyltrimethylammonium chloride, adjust the pH to 7.5 with hydrochloric acid, continue to maintain 80℃ water bath, react for 2 hours, cool to room temperature, filter, wash thoroughly with deionized water to remove chloride ions, dry in 105℃ oven for 8 hours, grind and pulverize, pass through a 200-mesh sieve to obtain organomontmorillonite carrier (hereinafter referred to as: organic soil).

[0047] Ten parts of organo-montmorillonite were weighed and added to a mixture of 300 parts of 0.12 mol / L copper chloride solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. Then, 0.1 parts of calcium chloride were added, and the mixture was stirred in a water bath for another 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 250°C for 3 hours to obtain a copper catalyst supported on organo-montmorillonite. The active component, calculated as copper ions, accounted for approximately 10% of the catalyst by mass, and is designated as #5.

[0048] Example 6

[0049] Weigh 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water, stir and dissolve at 80℃, add 20 parts of hexadecyltrimethylammonium chloride, adjust the pH to 7.5 with hydrochloric acid, continue to maintain 80℃ water bath, react for 2 hours, cool to room temperature, filter, wash thoroughly with deionized water to remove chloride ions, dry in 105℃ oven for 8 hours, grind and pulverize, pass through a 200-mesh sieve to obtain organomontmorillonite carrier (hereinafter referred to as: organic soil).

[0050] Ten parts of organo-montmorillonite were weighed and added to a mixture of 300 parts of 0.12 mol / L copper nitrate solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. Then, 0.1 parts of calcium chloride were added, and the mixture was stirred in a water bath for another 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 270°C for 3 hours to obtain a copper catalyst supported on organo-montmorillonite. The active component, calculated as copper ions, accounted for approximately 10% of the catalyst by mass, and is designated as #6.

[0051] Example 7

[0052] Weigh 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water, stir and dissolve at 80℃, add 15 parts of dodecyltrimethylammonium chloride, adjust the pH to 7.5 with hydrochloric acid, continue to maintain 80℃ water bath, react for 2 hours, cool to room temperature, filter, wash thoroughly with deionized water to remove chloride ions, dry in 105℃ oven for 8 hours, grind and pulverize, pass through a 200-mesh sieve to obtain organomontmorillonite carrier (hereinafter referred to as: organic soil).

[0053] Ten parts of organo-montmorillonite were weighed and added to a mixture of 300 parts of 0.12 mol / L copper nitrate solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. Then, 0.1 parts of potassium chloride were added, and the mixture was stirred in a water bath for another 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 260°C for 3 hours to obtain a copper catalyst supported on organo-montmorillonite. The active component, calculated as copper ions, accounted for approximately 10% of the catalyst by mass, and is designated as #7.

[0054] Comparative Example 1

[0055] Ten parts of purified sodium-based montmorillonite were weighed and added to a mixture of 300 parts of 0.12 mol / L copper nitrate solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. Then, 0.1 parts of potassium chloride were added, and the mixture was stirred in a water bath for another 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 250°C for 3 hours to obtain an organo-earth-supported copper catalyst. The active component, calculated as copper ions, accounted for approximately 10% of the catalyst by mass, and is designated as #8.

[0056] Comparative Example 2

[0057] Weigh 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water, stir and dissolve at 80℃, add 10 parts of tetradecyltrimethylammonium chloride, adjust the pH to 7.5 with hydrochloric acid, continue to maintain 80℃ water bath, react for 2 hours, cool to room temperature, filter, wash thoroughly with deionized water to remove chloride ions, dry in 105℃ oven for 8 hours, grind and pulverize, pass through a 200-mesh sieve to obtain organic soil carrier.

[0058] Ten parts of organic soil were weighed and added to a mixture of 300 parts of 0.12 mol / L copper nitrate solution and 100 parts of ethanol. The mixture was stirred in a water bath at 50°C for 6 hours. After cooling to room temperature, the mixture was filtered, washed, dried in an oven at 105°C for 8 hours, and calcined in air at 250°C for 3 hours to obtain a copper catalyst supported on organic soil. The active component, calculated as copper ions, accounted for approximately 10% of the catalyst by mass, and was designated as #9.

[0059] Catalyst characterization: The specific surface area and pore structure of the catalyst were determined using a Konta NOVA-2200e automated adsorption analyzer. The adsorbate was N2, and the adsorption temperature was 77 K. The specific surface area of ​​the sample was calculated using the BET equation, and the pore volume and pore size were calculated using the BJH method. The results are shown in Table 1.

[0060] Table 1 Catalyst Characterization

[0061]

[0062]

[0063] As shown in Table 1, the catalyst prepared by this invention has a large specific surface area and pore size. The specific surface area is related to the modifier of organomontmorillonite. The longer the chain length of the modifier and the greater the amount used, the larger the specific surface area, indicating that the intercalation modification effect is better and is conducive to the preparation of catalysts with large specific surface areas.

[0064] Application example:

[0065] Cyclohexanol dehydrogenation reaction conditions: Activity evaluation was conducted in a fixed-bed reactor with a catalyst loading of 50 mL. The catalyst was first reduced with H2 at atmospheric pressure and 260 °C for 3 h, and then subjected to a liquid hourly space velocity (LHSV) of 0.6 h⁻¹ for the feedstock cyclohexanol. -1 The activity was evaluated under reaction conditions of 220℃ and normal pressure, and the results are shown in Table 2.

[0066] Table 2. Catalyst performance evaluation results in the dehydrogenation of cyclohexanol to cyclohexanone reaction.

[0067] catalyst Cyclohexanol conversion rate / % Cyclohexanone selectivity / % Catalyst stability (hours) 1# 60.8 97.0 ≥2000 2# 67.0 99.8 ≥2000 3# 63.3 98.4 ≥2000 4# 62.2 98.1 ≥2000 5# 61.2 97.8 ≥2000 6# 64.9 99.5 ≥2000 7# 64.5 99.2 ≥2000 8# 45.6 90.1 ≥1000 9# 50.0 91.2 ≥1000

[0068] The catalyst performance evaluation results show that, at lower reaction temperatures, the catalyst exhibits good cyclohexanol conversion and cyclohexanone selectivity, with the catalyst reaching its optimal performance at a copper content of 10%. Furthermore, the catalysts in this group all demonstrate good stability, with a stability exceeding 2000 hours under the reaction conditions.

[0069] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A catalyst for the dehydrogenation of cyclohexanol to cyclohexanone at moderate to low temperatures, characterized in that, The catalyst is a copper catalyst supported on an organo-montmorillonite carrier. Copper species are loaded onto the carrier by an impregnation method. The copper ion content is 1% to 20% by mass percentage of the catalyst, and 0.1% to 2% of additives are doped. After washing, drying and calcination, the copper catalyst supported on organo-montmorillonite is obtained.

2. The catalyst according to claim 1, characterized in that, The carrier is purified sodium-based montmorillonite modified with an organic modifier.

3. The catalyst according to claim 2, characterized in that, The organic modifier is one of dodecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, or hexadecyltrimethylammonium chloride.

4. The catalyst according to claim 1, characterized in that, The auxiliary agent is one of sodium chloride, potassium chloride, or calcium chloride.

5. A method for preparing a medium-low temperature cyclohexanol dehydrogenation catalyst to cyclohexanone according to any one of claims 1 to 4, characterized in that it comprises the following steps: (1) Dissolve the purified sodium montmorillonite in water at 75-80℃, add an organic modifier, adjust the pH to 7-8, continue the reaction at the temperature for 2-3 hours, cool to room temperature, filter, wash, dry at 105-110℃ for 8-12 hours, grind and pulverize, and sieve to obtain the organic montmorillonite carrier. (2) Take the organo-montmorillonite support obtained in step (1), add a mixture of copper salt solution and ethanol, stir at 50-60℃ for 5-7h; add the additive, continue to keep warm and stir for 5-7h, cool to room temperature, filter, wash, dry at 105-110℃ for 8-12h, and calcine at 200-300℃ in air atmosphere for 3-4h to obtain the organo-montmorillonite supported copper catalyst.

6. The preparation method according to claim 5, characterized in that, In step (1), by weight, for every 50 parts of purified sodium montmorillonite, add 1000 parts of deionized water and 5 to 20 parts of organic modifier.

7. The preparation method according to claim 5, characterized in that, In step (2), by weight, 300 parts of copper salt solution and 100 parts of ethanol are added to every 10 parts of organomontmorillonite carrier.

8. The preparation method according to claim 5, characterized in that, In step (2), the copper salt solution is one of copper nitrate solution, copper sulfate solution or copper chloride solution with a concentration of 0.01 to 0.3 mol / L.

9. The preparation method according to claim 8, characterized in that, The concentration of the copper salt solution is 0.05–0.25 mol / L.

10. The use of the catalyst according to any one of claims 1 to 4 in the dehydrogenation of cyclohexanol to cyclohexanone.

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