Catalyst for preparing cyclohexanone by dehydrogenation of cyclohexanol and its preparation method

Abstract

The application belongs to the technical field of catalysts, and particularly relates to a cyclohexanol dehydrogenation cyclohexanone catalyst and a preparation method thereof. The application first uses hydrochloric acid to perform acid modification treatment on a palygorskite, then performs a hydrothermal synthesis reaction with copper chloride to obtain a palygorskite carrier material containing copper oxide quantum dots, and then performs liquid phase co-precipitation treatment on the carrier material to obtain a three-dimensional layered double hydroxide, so as to obtain the cyclohexanol dehydrogenation cyclohexanone catalyst, which not only improves the specific surface area of the catalyst, but also obtains a good cyclohexanol conversion rate and cyclohexanone selectivity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a cyclohexanol dehydrogenation cyclohexanone catalyst and a preparation method thereof. BACKGROUND

[0002] With the development of human society, the use of fossil fuels is increasing, and the environmental problems caused thereby are becoming increasingly prominent. In the face of increasingly severe environmental challenges, energy transformation is imperative. Hydrogen energy is attracting attention among many new energies due to its zero-carbon emission characteristics and high energy density advantages. The key problem in the large-scale application of hydrogen energy is the storage and transportation technology, which mainly reflects the storage density, safety and transportation efficiency. Gaseous hydrogen storage has the characteristics of fast charging and discharging speed, but due to its low density, the storage container is relatively large, and there is a risk of leakage and failure under high pressure. Liquid hydrogen storage requires extremely low temperature to maintain the liquefied state, and the energy consumed by the adiabatic system is too high. Solid-state hydrogen storage has high density, but hydrogen release usually requires high temperature conditions, and the kinetic performance is limited. Organic liquid hydrogen storage can be transported by using existing facilities, but the efficiency and selectivity of the catalyst for high-temperature dehydrogenation reaction are harsh.

[0003] Cyclohexanol, as an important chemical intermediate, its dehydrogenation reaction can generate important chemical raw material cyclohexanone and phenol, and is also a key link of organic liquid hydrogen storage technology. Cyclohexanol is a stable liquid at room temperature and normal pressure, and the theoretical hydrogen storage density is 6.7wt.%, which is higher than that of most metal hydrides and physical adsorption materials, and is a potential liquid hydrogen storage material. Cyclohexanol is stable in nature, not easy to decompose or deteriorate, non-toxic, suitable for long-term storage and long-distance transportation, and its liquid state characteristics can be seamlessly integrated into existing petroleum and chemical logistics infrastructure for transportation and storage, which significantly promotes the possibility of large-scale application. Cyclohexanol has low volatility, compared with some LOHCs (such as methyl formate) with low boiling point, which reduces the vapor loss and potential fire risk. Cyclohexanol is relatively abundant and has sustainable supply potential, and when used in large scale as a hydrogen storage carrier, its raw material supply chain foundation is relatively complete. Cyclohexanol dehydrogenation faces thermodynamic limitations and kinetic challenges, such as endothermic reaction, high C-H bond activation energy, and easy occurrence of hydrogenolysis side reactions, which leads to problems such as low-temperature activity of traditional catalysts, high-temperature carbon deposition and deactivation, and development of high-activity and high-selectivity catalysts becomes the core of the research in this field.

[0004] Chinese patent (publication number CN116920856B) discloses a cyclohexanol dehydrogenation catalyst for preparing cyclohexanone and a preparation method thereof. The invention uses purified sodium-based montmorillonite modified by a silane coupling agent as a copper-based cyclohexanol dehydrogenation catalyst for preparing cyclohexanone, which can effectively improve the specific surface area and thermal stability of the catalyst, increase the activity of the catalyst with low active component content, improve the utilization rate of the active component, and still has high activity and cyclohexanone selectivity and high thermal stability when the loading amount of the active component of the catalyst is less than 10%. However, the specific surface area of the catalyst is less studied in the technology, and the catalytic activity needs to be improved.

[0005] Therefore, how to design raw material components to prepare a cyclohexanol dehydrogenation catalyst for preparing cyclohexanone, effectively improve the specific surface area of the catalyst, and obtain good cyclohexanol conversion rate and cyclohexanone selectivity has become a direction to be studied. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a cyclohexanol dehydrogenation catalyst for preparing cyclohexanone and a preparation method thereof. The present application first uses hydrochloric acid to acid-modify attapulgite, then performs a hydrothermal synthesis reaction with copper chloride to obtain an attapulgite carrier material containing copper oxide quantum dots, and then performs liquid-phase co-precipitation treatment on the carrier material to form a three-dimensional layered double hydroxide, thereby obtaining a cyclohexanol dehydrogenation catalyst for preparing cyclohexanone, which not only improves the specific surface area of the catalyst but also obtains good cyclohexanol conversion rate and cyclohexanone selectivity.

[0007] In a first aspect of the present application, a preparation method of a cyclohexanol dehydrogenation catalyst for preparing cyclohexanone is provided, which comprises the following steps:

[0008] S1, first acid-modify attapulgite with hydrochloric acid to obtain acidified attapulgite; perform a hydrothermal synthesis reaction of the acidified attapulgite and copper chloride to obtain an attapulgite carrier material containing copper oxide quantum dots;

[0009] S2, dissolve zinc chloride and aluminum chloride in deionized water, then mix urea and sodium dodecyl sulfate, and then add the attapulgite carrier material to perform liquid-phase co-precipitation treatment to form a three-dimensional layered double hydroxide, thereby obtaining a cyclohexanol dehydrogenation catalyst for preparing cyclohexanone.

[0010] The attapulgite carrier material of the present application uses attapulgite as a base material, first acid-modifies the attapulgite with hydrochloric acid to dissolve the octahedral cations in the attapulgite, and the remaining tetrahedral silicon retains the crystal framework of the attapulgite, then adds copper chloride to perform a hydrothermal synthesis reaction, the copper ion has strong electron-donating ability, its rich orbital electrons can activate the ligand, realize the lattice reconstruction of the attapulgite, and the copper ion is adsorbed on the surface to form copper oxide quantum dots through in-situ hydrothermal reaction, thereby preparing the attapulgite carrier material.

[0011] As a preferred technical scheme of the present application, the step of acid modification treatment is: adding 2-4 parts of attapulgite into 100-120 parts of 3 mol / L hydrochloric acid solution, carrying out acid modification at 80-90 DEG C for 8-10 h, filtering, washing with deionized water, and drying to obtain acidified attapulgite.

[0012] As a preferred technical scheme of the present application, the weight fraction of the attapulgite can be 2 parts, 2.5 parts, 3 parts, 3.5 parts or 4 parts, etc.

[0013] As a preferred technical scheme of the present application, the weight fraction of the hydrochloric acid solution can be 100 parts, 105 parts, 110 parts, 115 parts or 120 parts, etc.

[0014] As a preferred technical scheme of the present application, the step of hydrothermal synthesis reaction is: dissolving 1.5-2.5 parts of copper chloride in 400-500 parts of deionized water, then adding 5-7 parts of acidified attapulgite and uniformly ultrasonic dispersing, carrying out hydrothermal reaction at 80-90 DEG C for 14-16 h, then carrying out heat preservation treatment, filtering, washing with deionized water, and constant temperature calcination.

[0015] As a preferred technical scheme of the present application, the weight fraction of the copper chloride can be 1.5 parts, 1.7 parts, 1.9 parts, 2.1 parts, 2.3 parts or 2.5 parts, etc.

[0016] As a preferred technical scheme of the present application, the weight fraction of the acidified attapulgite can be 5 parts, 5.5 parts, 6 parts, 6.5 parts or 7 parts, etc.

[0017] As a preferred technical scheme of the present application, the step of heat preservation treatment is: adding 40-50 parts of ammonia water, and then carrying out heat preservation at 70-80 DEG C for 2-4 h.

[0018] As a preferred technical scheme of the present application, the step of constant temperature calcination is: transferring into a muffle furnace for constant temperature calcination at 280-300 DEG C for 90-100 min.

[0019] In the attapulgite carrier material of the present application, the attapulgite can provide a natural high specific surface area substrate as a structure substrate, the ultra-small size of the copper oxide quantum dots greatly increases the specific surface area of the active component, and the comprehensive action improves the specific surface area of the catalyst; the active sites of the attapulgite can effectively anchor the copper oxide quantum dots through hydrogen bonds or chemical bonds, and the small size of the copper oxide quantum dots can expose more surface atoms to form active centers and enhance the activity of cyclohexanol dehydrogenation.

[0020] As a preferred technical scheme of the present application, the step of liquid phase coprecipitation treatment is: zinc chloride and aluminum chloride are added into deionized water in a weight ratio, mixed uniformly, then urea and sodium dodecyl sulfate are added and mixed uniformly, then the attapulgite carrier material containing copper oxide quantum dots is added and stirred for 30-40 min, and the reaction is carried out at 140-150 DEG C for 6-8 h, aging treatment, deionized water washing, and drying.

[0021] The present application uses zinc chloride and aluminum chloride as raw materials, and urea and sodium dodecyl sulfate as a template agent, and forms a three-dimensional layered double hydroxide on the attapulgite carrier material by liquid phase coprecipitation method, thereby preparing a cyclohexanol dehydrogenation to cyclohexanone catalyst loaded with three-dimensional layered double hydroxide and copper oxide quantum dots.

[0022] As a preferred technical scheme of the present application, the weight ratio of zinc chloride is 3-5 parts, the weight ratio of aluminum chloride is 1-3 parts, the weight ratio of deionized water is 100-120 parts, the weight ratio of urea is 3-5 parts, the weight ratio of sodium dodecyl sulfate is 0.6-0.8 parts, and the weight ratio of the attapulgite carrier material containing copper oxide quantum dots is 8-10 parts.

[0023] As a preferred technical scheme of the present application, the weight ratio of zinc chloride can be 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts, etc.

[0024] As a preferred technical scheme of the present application, the weight ratio of aluminum chloride can be 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, etc.

[0025] As a preferred technical scheme of the present application, the weight ratio of the attapulgite carrier material containing copper oxide quantum dots can be 8 parts, 8.5 parts, 9 parts, 9.5 parts or 10 parts, etc.

[0026] As a preferred technical scheme of the present application, the aging treatment condition is aging at 80-90 DEG C for 40-48 h.

[0027] The three-dimensional layered double hydroxide is composed of metal hydroxide layers and interlayer exchangeable anions, forming a nanoscale interlayer channel structure, and urea and sodium dodecyl sulfate are template agents for constructing the three-dimensional layered double hydroxide, which can form a layered porous microstructure, and the composite structure can improve the specific surface area of the catalyst; at the same time, the three-dimensional layered double hydroxide can form an electron-rich active site, which is more easily adsorbed to the hydroxyl group in the cyclohexanol molecule, thereby improving the catalytic activity.

[0028] In a second aspect, the present application provides a cyclohexanol dehydrogenation to cyclohexanone catalyst prepared by the preparation method of the first aspect.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] (1) The present application first uses hydrochloric acid to perform acid modification treatment on the attapulgite, then performs hydrothermal synthesis reaction with copper chloride to obtain the attapulgite carrier material containing copper oxide quantum dots, and then forms three-dimensional layered double hydroxide on the carrier material through liquid phase coprecipitation treatment, so that the catalyst for cyclohexanol dehydrogenation to cyclohexanone is obtained, which not only improves the specific surface area of the catalyst, but also obtains good cyclohexanol conversion rate and cyclohexanone selectivity.

[0031] (2) In the attapulgite carrier material of the present application, the attapulgite as a structural base can provide a natural high specific surface area base, and the ultra-small size of the copper oxide quantum dots greatly increases the specific surface area of the active component, and the comprehensive effect improves the specific surface area of the catalyst; the active sites of the attapulgite can effectively anchor the copper oxide quantum dots through hydrogen bonds or chemical bonds, and the small size of the copper oxide quantum dots can expose more surface atoms to form active centers, thereby enhancing the activity of cyclohexanol dehydrogenation.

[0032] (3) The three-dimensional layered double hydroxide of the present application is composed of metal hydroxide layers and interlayer exchangeable anions to form a nanoscale interlayer channel structure, and urea and sodium dodecyl sulfate are template agents for constructing the three-dimensional layered double hydroxide, which can form a layered porous microstructure, and the specific surface area of the catalyst can be improved through the composite structure; at the same time, the three-dimensional layered double hydroxide can form an electron-rich active site, which is more easily adsorbed by the hydroxyl group in the cyclohexanol molecule, thereby improving the catalytic activity. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed for the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 XRD spectra of copper oxide, attapulgite, acidified attapulgite and attapulgite carrier material in Example 1 of the present application. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the present application, the present application lists the following examples. Those skilled in the art should understand that the examples are only to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0036] Some components in the examples and comparative examples are as follows:

[0037] Attapulgite, item A921976, purchased from Shanghai Maikelin Biochemical Technology Co., Ltd.;

[0038] Copper chloride, CAS No. 10125-13-0, purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0039] Zinc chloride, CAS No. 7646-85-7, purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.;

[0040] Aluminum chloride, CAS No. 7784-13-6, purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0041] Example 1

[0042] The embodiment provides a preparation method of a cyclohexanol dehydrogenation cyclohexanone catalyst, comprising the following steps:

[0043] S1, 4 parts of attapulgite are added to 120 parts of 3mol / L hydrochloric acid solution, acid modification is carried out at 90℃ for 8h, suction filtration, deionized water washing, drying, and acidified attapulgite is obtained; 2.5 parts of copper chloride is dissolved in 500 parts of deionized water, then 7 parts of acidified attapulgite is uniformly dispersed by ultrasonic, hydrothermal reaction is carried out at 90℃ for 16h, then 50 parts of ammonia water is added and kept at 80℃ for 2h, suction filtration, deionized water washing, and the attapulgite carrier material containing copper oxide quantum dots is obtained by transferring into a muffle furnace and keeping at 300℃ for 90min.

[0044] S2, 5 parts of zinc chloride and 3 parts of aluminum chloride are added to 120 parts of deionized water and uniformly mixed, then 5 parts of urea and 0.8 parts of sodium dodecyl sulfate are uniformly mixed, 10 parts of the attapulgite carrier material containing copper oxide quantum dots is added and stirred for 40min, reaction is carried out at 150℃ for 6h, aging is carried out at 90℃ for 40h, deionized water washing, and drying, and the cyclohexanol dehydrogenation cyclohexanone catalyst is obtained.

[0045] Example 2

[0046] The embodiment provides a preparation method of a cyclohexanol dehydrogenation cyclohexanone catalyst, comprising the following steps:

[0047] S1, 4 parts of attapulgite are added to 120 parts of 3mol / L hydrochloric acid solution, acid modification is carried out at 90℃ for 8h, suction filtration, deionized water washing, drying, and acidified attapulgite is obtained; 2.5 parts of copper chloride is dissolved in 500 parts of deionized water, then 7 parts of acidified attapulgite is uniformly dispersed by ultrasonic, hydrothermal reaction is carried out at 90℃ for 16h, then 50 parts of ammonia water is added and kept at 80℃ for 2h, suction filtration, deionized water washing, and the attapulgite carrier material containing copper oxide quantum dots is obtained by transferring into a muffle furnace and keeping at 300℃ for 90min.

[0048] S2, 3 parts of zinc chloride and 1 part of aluminum chloride are added into 100 parts of deionized water to mix uniformly, then 3 parts of urea and 0.6 parts of sodium dodecyl sulfate are mixed uniformly, 8 parts of the attapulgite carrier material containing copper oxide quantum dots are added and stirred for 30 min, and the reaction is carried out at 140℃ for 8 h, and the aging is carried out at 80℃ for 48 h, and then deionized water washing and drying are carried out to obtain the catalyst for preparing cyclohexanone from cyclohexanol by dehydrogenation.

[0049] Example 3

[0050] The embodiment provides a preparation method of a catalyst for preparing cyclohexanone from cyclohexanol by dehydrogenation, comprising the following steps:

[0051] S1, 3 parts of attapulgite are added into 110 parts of 3 mol / L hydrochloric acid solution to carry out acid modification at 85℃ for 9 h, and then filtration, deionized water washing and drying are carried out to obtain acidified attapulgite; 2.2 parts of copper chloride is dissolved in 450 parts of deionized water, then 6 parts of the acidified attapulgite is uniformly dispersed by ultrasonic, and then hydrothermal reaction is carried out at 85℃ for 15 h, and then 45 parts of ammonia water is added and kept at 75℃ for 3 h, and then filtration, deionized water washing and calcination in a muffle furnace at 290℃ for 95 min are carried out to obtain the attapulgite carrier material containing copper oxide quantum dots;

[0052] S2, 3 parts of zinc chloride and 1 part of aluminum chloride are added into 100 parts of deionized water to mix uniformly, then 3 parts of urea and 0.6 parts of sodium dodecyl sulfate are mixed uniformly, 8 parts of the attapulgite carrier material containing copper oxide quantum dots are added and stirred for 30 min, and the reaction is carried out at 140℃ for 8 h, and the aging is carried out at 80℃ for 48 h, and then deionized water washing and drying are carried out to obtain the catalyst for preparing cyclohexanone from cyclohexanol by dehydrogenation.

[0053] Comparative Example 1

[0054] The difference between the comparative example and the example 1 is that the three-dimensional layered double hydroxide is not prepared, and the attapulgite carrier material containing copper oxide quantum dots is directly used as the catalyst.

[0055] Comparative Example 2

[0056] The difference between the comparative example and the example 1 is that the attapulgite is not subjected to acid modification treatment.

[0057] Comparative Example 3

[0058] The difference between the comparative example and the example 1 is that the acidified attapulgite is directly used as the carrier material to carry out the liquid phase coprecipitation treatment.

[0059] The performance of the above examples and comparative examples is tested, and the test method is as follows:

[0060] (1) Specific surface area test: test according to the requirements of GB / T 19587-2017 Gas adsorption BET method for determination of specific surface area of solid substances.

[0061] (2) Catalyst activity test: the catalysts of the examples and the comparative examples are used for the reaction of cyclohexanol dehydrogenation to cyclohexanone to compare the activity of the catalysts, the reaction is carried out in a fixed bed reactor, the catalyst is first reduced with hydrogen at 260℃ under normal pressure for 3h, and then the reaction is carried out under the reaction conditions of 0.6h -1 -1 of raw material cyclohexanol liquid, a reaction temperature of 250℃ and normal pressure.

[0062] The performance test data are shown in Table 1.

[0063]

[0064] From the above, the present application uses attapulgite as a base material, first uses hydrochloric acid to perform acid modification treatment on the attapulgite, then adds copper chloride to perform a hydrothermal synthesis reaction to form copper oxide quantum dots, and then cooperates with zinc chloride, aluminum chloride, urea and sodium dodecyl sulfate to form three-dimensional layered double hydroxide on the carrier material through a liquid phase coprecipitation method, so as to obtain a cyclohexanol dehydrogenation to cyclohexanone catalyst (Examples 1~3), which has better comprehensive performance.

[0065] Compared with Example 1, no three-dimensional layered double hydroxide is prepared, and the attapulgite carrier material containing copper oxide quantum dots is directly used as a catalyst, so that the effect of the three-dimensional layered double hydroxide is lacking, the specific surface area is smaller, and the catalytic activity is poorer (Comparative Example 1); compared with Example 1, the attapulgite is not subjected to acid modification treatment, and the subsequent preparation effect is poor, so that the specific surface area is smaller, and the catalytic activity is poorer (Comparative Example 2); compared with Example 1, the acidified attapulgite is directly used as a carrier material to perform liquid phase coprecipitation treatment, so that the effect of copper oxide quantum dots is lacking, the specific surface area is smaller, and the catalytic activity is poorer (Comparative Example 3).

Claims

1.A method for preparing a catalyst for preparing cyclohexanone by dehydrogenation of cyclohexanol, comprising the following steps: S1, first acid-modifying palygorskite with hydrochloric acid to obtain acidified palygorskite; and then hydrothermally synthesizing the acidified palygorskite and copper chloride to obtain a palygorskite carrier material containing copper oxide quantum dots; S2, dissolving zinc chloride and aluminum chloride in deionized water, then adding urea and sodium dodecyl sulfate and mixing, and then adding the palygorskite carrier material to form a three-dimensional layered double hydroxide by liquid-phase co-precipitation treatment to obtain the catalyst for preparing cyclohexanone by dehydrogenation of cyclohexanol. 2.The method according to claim 1, wherein the acid-modifying step is: adding 2-4 parts of palygorskite to 100-120 parts of a 3 mol / L hydrochloric acid solution, acid-modifying at 80-90 ℃ for 8-10 h, filtering, washing with deionized water, and drying to obtain acidified palygorskite. 3.The method according to claim 1, wherein the hydrothermal synthesis step is: dissolving 1.5-2.5 parts of copper chloride in 400-500 parts of deionized water, then adding 5-7 parts of acidified palygorskite and uniformly ultrasonic dispersing, hydrothermal reaction at 80-90 ℃ for 14-16 h, then heat preservation, filtering, washing with deionized water, and constant temperature calcination. 4.The method according to claim 3, wherein the heat preservation step is: adding 40-50 parts of ammonia water, and then heat preservation at 70-80 ℃ for 2-4 h. 5.The method according to claim 3, wherein the constant temperature calcination step is: transferring to a muffle furnace for constant temperature calcination at 280-300 ℃ for 90-100 min. 6.The method according to claim 1, wherein the liquid-phase co-precipitation treatment step is: adding zinc chloride and aluminum chloride to deionized water and mixing uniformly, then adding urea and sodium dodecyl sulfate and mixing, and then adding the palygorskite carrier material containing copper oxide quantum dots and stirring for 30-40 min, reaction at 140-150 ℃ for 6-8 h, aging treatment, washing with deionized water, and drying. 7.The method according to claim 6, wherein the zinc chloride is 3-5 parts, the aluminum chloride is 1-3 parts, the deionized water is 100-120 parts, the urea is 3-5 parts, the sodium dodecyl sulfate is 0.6-0.8 parts, and the palygorskite carrier material containing copper oxide quantum dots is 8-10 parts. 8.The method according to claim 6, wherein the aging treatment is performed at 80-90 ℃ for 40-48 h. ​ ​ ​ ​ ​ ​ ​ ​ 9. A catalyst for dehydrogenation of cyclohexanol to cyclohexanone, characterized by The process according to any one of claims 1 to 8.

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