Dehydrogenation catalysts, their preparation methods and applications, and methods for preparing cyclohexanone.

Abstract

This invention relates to the field of catalyst technology, specifically to a dehydrogenation catalyst, its preparation method and application, and a method for preparing cyclohexanone. The catalyst comprises a core and a shell covering the core; the core is a first dehydrogenation active component oxide, and the shell is SiO2 doped with a second dehydrogenation active component oxide; the SiO2 has a chain-like silicon-oxygen tetrahedral structure. The dehydrogenation catalyst provided by this invention, on the one hand, improves catalyst performance through the dispersion of the active component, and on the other hand, the chain-like Si-O tetrahedra form a unique porous structure with a large specific surface area. The dehydrogenation catalyst of this invention, when used for dehydrogenation, such as the dehydrogenation of alcohols to ketones, has the advantages of high alcohol conversion and high ketone selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a dehydrogenation catalyst, its preparation method and application, and a method for preparing cyclohexanone. Background Technology

[0002] Cyclohexanone is an important organic chemical raw material with a wide range of applications. It can generally be divided into two main categories based on its application: amide-based and non-amide-based. Amide-based cyclohexanone is mainly used in the production of caprolactam and adipic acid, accounting for approximately 70% of the total domestic demand for cyclohexanone. Non-amide-based cyclohexanone is mainly used as an organic solvent. Due to its strong dissolving power, low toxicity, and low price, it is widely used in various coatings, paints, inks, resin solvents and diluents, as well as solvents for coating photosensitive and magnetic recording materials. There are three main industrial production methods for cyclohexanone: the phenol method, the cyclohexane method, and the cyclohexene method. All of these methods involve the key step of dehydrogenating cyclohexanol to produce cyclohexanone.

[0003] The application of catalysts for the dehydrogenation of cyclohexanol to cyclohexanone has shifted from the earliest Zn / Ca and Cu / Mg systems to the now commonly used Cu, Zn / Al, and Cu / Si systems, reflecting a transition from high-temperature to low-temperature applications.

[0004] CN104437488A discloses a method for preparing a catalyst for the gas-phase dehydrogenation of cyclohexanol to cyclohexanone. The method employs a stepwise precipitation process, first precipitating silica sol, and then further precipitating copper nitrate to obtain a Cu / Si cyclohexanol dehydrogenation catalyst.

[0005] CN102408305A relates to a method for catalytic conversion between ketones and alcohols, which uses one or more of nickel, ketones and cobalt as active components and silane groups grafted after silylation treatment as carriers to achieve the interconversion of alcohols and ketones.

[0006] CN1356170A relates to a catalyst for the dehydrogenation of cyclohexanol to cyclohexanone, which mainly includes copper oxide, zinc oxide, aluminum oxide, and rare metal compounds and alkali metal compounds as promoters.

[0007] CN103285902A provides a catalyst for the dehydrogenation of cyclohexanol to cyclohexanone, its preparation method and application. The catalyst includes a support and a dehydrogenation active component supported on the support. The support is a donut-shaped SBA-15, which has higher activity and selectivity compared with dehydrogenation catalysts using alumina or the like as supports.

[0008] CN103285847A discloses a catalyst for the dehydrogenation of cyclohexanol to cyclohexanone, its preparation method, and its application. The active component of the dehydrogenation catalyst contains Zn, Ca, and Ba elements. The dehydrogenation catalyst is prepared by co-precipitation of a salt solution of the active component and a precipitant in the presence of an organic compound containing a hydroxyl functional group.

[0009] Applications have revealed that conventional Cu / Zn / Al cyclohexanol dehydrogenation catalysts exhibit relatively poor selectivity in the dehydrogenation reaction of high-purity cyclohexanol feedstocks, while Cu / Si-based cyclohexanol dehydrogenation catalysts show slightly insufficient conversion rates under high space velocities of cyclohexanol feedstocks. Therefore, improving catalyst loading and cyclohexanol conversion while maintaining cyclohexanone selectivity is currently a key research focus for cyclohexanol dehydrogenation catalysts. Summary of the Invention

[0010] The purpose of this invention is to overcome the problems of low activity and poor selectivity of high-load dehydrogenation catalysts in the prior art, and to provide a dehydrogenation catalyst, its preparation method and application, and a method for preparing cyclohexanone. The active components of this dehydrogenation catalyst are highly dispersed, and it has the advantages of high alcohol conversion and high ketone selectivity when used for alcohol dehydrogenation to ketone.

[0011] To achieve the above objectives, a first aspect of the present invention provides a dehydrogenation catalyst comprising a core and a shell covering the core; the core is a first dehydrogenation active component oxide, and the shell is SiO2 doped with a second dehydrogenation active component oxide; the SiO2 has a chain-like silicon-oxygen tetrahedral structure.

[0012] A second aspect of the present invention provides a method for preparing the dehydrogenation catalyst of the present invention, the method comprising:

[0013] (1) Mix the solution containing the first dehydrogenation active component source with an alkaline solution and react to obtain a suspension containing the first dehydrogenation active component seed crystals;

[0014] (2) Add SiO2 source to alkaline solution for etching to obtain silicate solution;

[0015] (3) Mix the silicate solution in step (2) with the solution containing the second dehydrogenation active component source, and then add it in parallel with the alkaline solution to the suspension containing the first dehydrogenation active component seed crystal in step (1), control the pH to 7-9, and carry out aging.

[0016] (4) The suspension obtained by aging is separated to obtain a precipitate, which is then washed, dried and calcined to obtain a dehydrogenation catalyst.

[0017] A third aspect of the present invention provides the application of the dehydrogenation catalyst described herein in the dehydrogenation of alcohols to ketones.

[0018] A fourth aspect of the present invention provides a method for preparing cyclohexanone, wherein the method comprises:

[0019] (I) The dehydrogenation catalyst is reduced in a reducing gas atmosphere;

[0020] (II) In the presence of the catalyst obtained in step (I), cyclohexanol is vaporized using nitrogen as a carrier gas, and cyclohexanol is dehydrogenated to produce cyclohexanone.

[0021] Through the above technical solution, the dehydrogenation catalyst provided by the present invention improves the performance of the catalyst by dispersing the active components. On the other hand, the chain-like Si-O tetrahedra form a unique pore structure with a large specific surface area. In the chain-like Si-O tetrahedra, the second dehydrogenation active component metal (e.g., Cu, Zn) can coordinate with the oxygen in the chain-like silicon-oxygen tetrahedra, further improving the stability of the catalyst.

[0022] The dehydrogenation catalyst of this invention has the advantages of high alcohol conversion and high ketone selectivity when used for dehydrogenation, such as alcohol dehydrogenation to ketone. In particular, when used for cyclohexanol dehydrogenation to cyclohexanone, the core-shell structure of the catalyst of this invention disperses the active components and improves the conversion rate of cyclohexanol. On the other hand, the chain-like Si-O tetrahedra form a unique pore structure, which is beneficial to improving the selectivity of cyclohexanone. Moreover, the siloxy groups are hydrophilic and oleophobic, which can quickly adsorb cyclohexanol for reaction and quickly desorb the reacted cyclohexanone from the catalyst surface. This makes the catalyst maintain excellent performance under high load and has excellent stability. Attached Figure Description

[0023] Figure 1 This is a high-resolution HRTEM image of the catalyst prepared in Example 1;

[0024] Figure 2 This is a HAADF and mapping elemental distribution diagram of the catalyst prepared in Example 1; wherein, Figure 2 d is the HAADF diagram of the catalyst. Figure 2 a is the copper element mapping diagram. Figure 2 b is the silicon element mapping diagram. Figure 2 c is the zinc element mapping diagram;

[0025] Figure 3 This is a schematic diagram of the structure of the catalyst shell chain-like silicon-oxygen tetrahedron prepared in Example 1. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] In this invention, the content of each component is calculated based on the amount of raw materials used.

[0028] In this invention, unless otherwise specified, "solution" refers to an aqueous solution.

[0029] The first aspect of this invention provides a dehydrogenation catalyst comprising a core and a shell covering the core; the core is a first dehydrogenation active component oxide, and the shell is SiO2 doped with a second dehydrogenation active component oxide; the SiO2 has a chain-like silicon-oxygen tetrahedral structure. The dehydrogenation catalyst provided by this invention, on the one hand, improves catalyst performance through the dispersion of the active component; on the other hand, the chain-like Si-O tetrahedra form a unique porous structure with a large specific surface area. Furthermore, in the shell, the second dehydrogenation active component metal (e.g., Cu, Zn) can coordinate with oxygen in the chain-like silicon-oxygen tetrahedra, further improving the catalyst's stability.

[0030] According to a preferred embodiment of the present invention, the total content of the first dehydrogenation active component oxide and the second dehydrogenation active component oxide in the dehydrogenation catalyst is 60wt%-80wt% by mass, and the SiO2 content is 20wt%-40wt%.

[0031] According to a preferred embodiment of the present invention, the content of the first dehydrogenation active component oxide is 15-45% by weight, preferably 15-20% by weight, based on the total weight of the active component oxides, and the content of the second dehydrogenation active component oxide is 15-60% by weight, preferably 45-60% by weight.

[0032] According to a preferred embodiment of the present invention, the catalyst has a specific surface area of ​​235-450 m². 2 / g.

[0033] According to a preferred embodiment of the present invention, the catalyst has a pore size of 25-48 nm.

[0034] According to a preferred embodiment of the present invention, the first dehydrogenation active component and the second dehydrogenation active component are each selected from copper and / or zinc.

[0035] According to a preferred embodiment of the present invention, the first dehydrogenation active component is copper, and the second dehydrogenation active component is zinc.

[0036] A second aspect of the present invention provides a method for preparing the dehydrogenation catalyst of the present invention, the method comprising:

[0037] (1) Mix the solution containing the first dehydrogenation active component source with an alkaline solution and react to obtain a suspension containing the first dehydrogenation active component seed crystals;

[0038] (2) Add SiO2 source to alkaline solution for etching to obtain silicate solution;

[0039] (3) Mix the silicate solution in step (2) with the solution containing the second dehydrogenation active component source, and then add it in parallel with the alkaline solution to the suspension containing the first dehydrogenation active component seed crystal in step (1), control the pH to 7-9, and carry out aging.

[0040] (4) The suspension obtained by aging is separated to obtain a precipitate, which is then washed, dried and calcined to obtain a dehydrogenation catalyst.

[0041] Using the preparation method of the present invention, the active component hydroxide is used as the matrix seed crystal. The SiO2 structure is etched with an alkaline solution to obtain a silicate solution. A mixed salt solution containing the active component source is added to the etched silicate solution. Then, the mixed salt solution and the alkaline solution are added to the matrix seed crystal to form a core with an active component oxide and a surface covered with a Si-O tetrahedral chain structure shell coordinated with active component ions. The dehydrogenation catalyst of the present invention is obtained by calcination.

[0042] In this invention, the reaction temperature in step (1) can be selected from a wide range. According to a preferred embodiment of this invention, the reaction temperature is 50-70℃.

[0043] In this invention, there are no special requirements for the mixing method in step (1). Conventional stirring and mixing can achieve the purpose of this invention. Preferably, the solution containing the first dehydrogenation active component source and the alkaline solution are added to the reaction in parallel.

[0044] In this invention, in step (1), there is no particular limitation on the concentration of active component ions in the solution containing the first dehydrogenation active component source. According to a preferred embodiment of this invention, the concentration of the first dehydrogenation active component ions in the solution containing the first dehydrogenation active component source is 0.5-2.5 mol / L.

[0045] In this invention, in step (1), there is no particular limitation on the concentration of hydroxide ions in the alkaline solution. According to a preferred embodiment of this invention, the concentration of hydroxide ions in the alkaline solution is 1.5-2.5 mol / L.

[0046] According to a preferred embodiment of the present invention, the molar ratio of the first dehydrogenation active component ion to hydroxide ion is 1:2-3.

[0047] According to a preferred embodiment of the present invention, in step (2), the SiO2 source is SiO2, the molar ratio of SiO2 to hydroxide ions in the alkaline solution is 1-2.5:1, and the concentration of hydroxide ions in the alkaline solution is 1.25-2.5 mol / L.

[0048] According to a preferred embodiment of the present invention, in step (2), etching is performed for 10-60 minutes.

[0049] In this invention, there is no particular limitation on the co-current mixing method in step (3). Conventional mixing methods in the art can achieve the purpose of this invention, such as stirring, ultrasonication, and oscillation. Preferably, co-current mixing is carried out under the action of ultrasonic waves. Preferably, the frequency of ultrasonic waves is 40-80KHz. This is beneficial to promote the formation of chain-like Si-O tetrahedra with ion coordination of active components and surface active components, and to enhance the dispersion of active components.

[0050] In this invention, in step (3), there is no particular limitation on the concentration of the second dehydrogenation active component ion in the solution containing the second dehydrogenation active component source. According to a preferred embodiment of this invention, the concentration of the second dehydrogenation active component ion in the solution containing the second dehydrogenation active component source is 0.5-2.5 mol / L.

[0051] According to a preferred embodiment of the present invention, in step (3), the concentration of hydroxide ions in the alkaline solution is 1.25-2.5 mol / L.

[0052] According to a preferred embodiment of the present invention, in step (3), the mass ratio of silicate solution to second dehydrogenation active component source solution is 0.2-2:1.

[0053] In this invention, there is no particular limitation on the aging conditions. Conventional aging conditions in the art can achieve the purpose of this invention. Preferably, in step (3), the aging conditions include: a temperature of 60-80℃. The aging time can be reasonably adjusted according to the requirements. Preferably, the aging time is 20-60 min.

[0054] In this invention, there is no particular limitation on the roasting conditions in step (4). Conventional roasting conditions in the art can achieve the purpose of this invention. Preferably, the roasting conditions include: a roasting temperature of 140-350℃, and a roasting time that is reasonably adjusted according to the roasting temperature. Preferably, the roasting time is 12-24h.

[0055] According to a preferred embodiment of the present invention, a gradient heating calcination is adopted, first raising the temperature from room temperature to 140-160°C and holding for 2-4 hours, then raising the temperature to 220-300°C and holding for 8-16 hours, and finally raising the temperature to 320-350°C and holding for 2-4 hours; this is beneficial to promoting the formation of active components and chain-like Si-O tetrahedra, and enhancing the dispersion of active components.

[0056] In this invention, there are no particular limitations on the first and second dehydrogenation active component sources. Conventional dehydrogenation active component sources in the art can achieve the purpose of this invention. Preferably, the first and second dehydrogenation active component sources are each selected from at least one soluble metal salt of the active component. Preferably, the first and second dehydrogenation active component sources are each selected from at least one nitrate, hydrochloride, and sulfate of the dehydrogenation active component, such as at least one of copper nitrate, copper chloride, zinc nitrate, and zinc chloride.

[0057] In this invention, there is no particular limitation on the SiO2 source. Conventional SiO2 sources in the art can achieve the purpose of this invention. Preferably, the SiO2 source is selected from at least one of silica, tetraethyl orthosilicate, silica sol and silica.

[0058] According to a preferred embodiment of the present invention, the alkali is selected from potassium hydroxide and / or sodium hydroxide.

[0059] A third aspect of the present invention provides the application of the dehydrogenation catalyst described herein in the dehydrogenation of alcohols to ketones. Preferably, the alcohol is selected from at least one of cyclohexanol, cyclopentanol, and isononol.

[0060] A fourth aspect of the present invention provides a method for preparing cyclohexanone, wherein the method comprises:

[0061] (I) The dehydrogenation catalyst is reduced in a reducing gas atmosphere;

[0062] (II) In the presence of the catalyst obtained in step (I), using nitrogen as a carrier gas, cyclohexanol is vaporized and dehydrogenated to produce cyclohexanone; the dehydrogenation catalyst includes the dehydrogenation catalyst described in this invention. The dehydrogenation catalyst described in this invention has the advantages of high cyclohexanol conversion and high cyclohexanone selectivity when used for the dehydrogenation of cyclohexanol to cyclohexanone.

[0063] In this invention, the reduction conditions in step (I) are not particularly limited and can be conventional reduction conditions in the art. Preferably, the reduction conditions include: a temperature of 120-230°C and a time of 12-24h; preferably, the temperature is increased gradually, from room temperature to 120-140°C and held for 2-4h, then increased to 160-180°C and held for 8-16h, then increased to 200-230°C and held for 2-4h.

[0064] In this invention, there is no particular limitation on the reducing gas. Conventional reducing gases in the art can achieve the purpose of this invention. Preferably, the reducing gas is selected from at least one of hydrogen, a mixture of hydrogen and an inert gas, such as a mixture of hydrogen and nitrogen.

[0065] In this invention, there are no particular limitations on the dehydrogenation conditions. Conventional dehydrogenation conditions in the art can achieve the purpose of this invention. Preferably, in step (II), the dehydrogenation conditions include: a temperature of 200-250°C, a pressure of 0.1-0.3 MPa, and a cyclohexanol liquid hourly space velocity of 1.0-1.5 h⁻¹. -1 The N2 flow rate is 400-600 ml / min.

[0066] The present invention will be described in detail below through embodiments.

[0067] In the following examples, the specific surface area and pore size of the catalyst were tested using a BET adsorption-desorption apparatus.

[0068] Example 1

[0069] (1) Weigh 233.8g of Cu(NO3)2 and 466.7g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution; take 0.5L of Cu-Zn mixed solution, weigh 75g of sodium hydroxide to prepare 1L of alkaline solution, and add the two in parallel to a stirred reactor containing 1L of deionized water at 55℃ to obtain a suspension containing Cu(OH)2 and Zn(OH)2 seeds;

[0070] (2) Weigh 260g of silicic acid and add it to 1L of alkaline solution prepared with 100g of NaOH. After etching for 20min, a silicate solution is obtained.

[0071] (3) Add the remaining 1.5 L Cu-Zn mixed solution to the silicate solution in step (2), mix evenly, and then add it in parallel with 3 L of alkaline solution prepared with 225 g sodium hydroxide under the action of ultrasound to the seed suspension in step (1), adjust the final pH to 7, and age at 65°C for 30 min to obtain the suspension.

[0072] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 140°C and held for 4 hours. The temperature is then raised to 250°C and held for 12 hours. The temperature is then raised to 320°C and held for 4 hours. The dehydrogenation catalyst C1 is obtained by calcination, wherein SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0073] Figure 1 This is a high-resolution HRTEM image of the catalyst prepared in Example 1. Figure 3This is a schematic diagram of the chain-like Si-O tetrahedral structure of the catalyst shell, in which Cu and Zn in the shell are coordinated with oxygen in the chain-like silicon-oxygen tetrahedra.

[0074] Figure 2 This is a HAADF and mapping elemental distribution diagram of the catalyst prepared in Example 1; wherein, Figure 2 d is the HAADF diagram of the catalyst. Figure 2 a is the copper element mapping diagram. Figure 2 b is the silicon element mapping diagram. Figure 2 c is the zinc element mapping diagram, indicating that the elements in the catalyst are evenly distributed.

[0075] Example 2

[0076] (1) Weigh 350g of Cu(NO3)2 and 466.7g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution; take 0.5L of Cu-Zn mixed solution, weigh 87g of sodium hydroxide to prepare 1L of alkaline solution, and add the two in parallel to a stirred reactor containing 1L of deionized water at 50℃ to obtain a suspension containing Cu(OH)2 and Zn(OH)2 seed crystals;

[0077] (2) Weigh 520g of tetraethyl orthosilicate and add it to 1L of alkaline solution prepared with 75g of NaOH. After etching for 30min, a silicate solution is obtained.

[0078] (3) Add the remaining 1.5 L Cu-Zn mixed solution to the silicate solution in step (2), mix evenly, and then add it in parallel with 3 L of alkaline solution prepared with 261 g sodium hydroxide under the action of ultrasound to the seed suspension in step (1). Adjust the final pH to 8. After the reaction is completed, age at 60 °C for 40 min to obtain the suspension.

[0079] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 160°C and held for 2 hours. The temperature is then raised to 300°C and held for 16 hours. The temperature is then raised to 350°C and held for 2 hours. The dehydrogenation catalyst C2 is obtained by calcination, wherein SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0080] Example 3

[0081] (1) Weigh 233.8g of Cu(NO3)2 and 700g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution. Take 0.5L of Cu-Zn mixed solution, weigh 100g of sodium hydroxide to prepare 1L of alkaline solution, and add the two in parallel to a stirred reactor containing 1L of deionized water at 60℃ to obtain a suspension containing Cu(OH)2 and Zn(OH)2 seed crystals.

[0082] (2) Weigh 110g of silica and add it to 1L of alkaline solution prepared with 50g of NaOH. After etching for 40min, a silicate solution is obtained.

[0083] (3) Add the remaining 1.5L Cu-Zn mixed solution to the silicate solution in step (2), mix evenly, and then add it in parallel with 3L alkaline solution prepared with 300g sodium hydroxide under the action of ultrasound to the seed suspension in step (1), adjust the final pH to 9, and age at 70℃ for 20min to obtain the suspension.

[0084] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 150°C and held for 3 hours. The temperature is then raised to 260°C and held for 10 hours. The temperature is then raised to 330°C and held for 3 hours. The dehydrogenation catalyst C3 is obtained by calcination. In the catalyst shell, SiO2 is a chain-like silicon-oxygen tetrahedron.

[0085] Example 4

[0086] (1) Weigh 292g of Cu(NO3)2 and 525g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution, take 0.5L of Cu-Zn mixed solution, weigh 87.5g of sodium hydroxide to prepare 1L of alkaline solution, and add the two in parallel to a stirred reactor containing 1L of deionized water at 70℃ to obtain a suspension containing Cu(OH)2 and Zn(OH)2 seed crystals;

[0087] (2) Weigh 195g of silicic acid and add it to 1L of alkaline solution prepared with 80g of NaOH. After etching for 20min, a silicate solution is obtained.

[0088] (3) Add the remaining 1.5 L Cu-Zn mixed solution to the silicate solution in step (2), mix evenly, and then add it in parallel with 3 L of alkaline solution prepared with 262.5 g sodium hydroxide under the action of ultrasound to the seed suspension in step (1), adjust the final pH to 7, and age at 80℃ for 20 min to obtain the suspension.

[0089] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 140°C and held for 4 hours. The temperature is then raised to 240°C and held for 16 hours. The temperature is then raised to 340°C and held for 2 hours. The calcination yields the dehydrogenation catalyst C4, wherein SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0090] Example 5

[0091] (1) Weigh 292g of Cu(NO3)2 and 583g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution, take 0.5L of Cu-Zn mixed solution, weigh 93g of sodium hydroxide to prepare 1L of alkaline solution, and add the two in parallel to a stirred reactor containing 1L of deionized water at 65℃ to obtain a suspension containing Cu(OH)2 and Zn(OH)2 seed crystals;

[0092] (2) Weigh 433g of tetraethyl orthosilicate and add it to 1L of alkaline solution prepared with 80g of NaOH. After etching for 30min, a silicate solution is obtained.

[0093] (3) Add the remaining 1.5 L Cu-Zn mixed solution to the silicate solution in step (2), mix evenly, and then add it in parallel with 3 L of alkaline solution prepared with 279 g sodium hydroxide to the seed suspension in step (1) under the action of ultrasound. Adjust the final pH to 8. After the reaction is completed, age at 75 °C for 20 min to obtain the suspension.

[0094] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 150°C and held for 4 hours. The temperature is then raised to 280°C and held for 16 hours. The temperature is then raised to 340°C and held for 4 hours. The calcination yields dehydrogenation catalyst C5, wherein SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0095] Example 6

[0096] (1) Weigh 292g of Cu(NO3)2 and 641g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution, take 0.5L of Cu-Zn mixed solution, weigh 100g of sodium hydroxide to prepare 1L of alkaline solution, and add the two in parallel to a stirred reactor containing 1L of deionized water at 65℃ to obtain a suspension containing Cu(OH)2 and Zn(OH)2 seed crystals;

[0097] (2) Weigh 110g of silica and add it to 1L of alkaline solution prepared with 50g of NaOH. After etching for 20min, a silicate solution is obtained.

[0098] (3) Add the remaining 1.5 L Cu-Zn mixed solution to the silicate solution in step (2), mix evenly, and then add it in parallel with 3 L of alkaline solution prepared with 300 g sodium hydroxide to the seed suspension in step (1) under the action of ultrasound. Adjust the final pH to 7. After the reaction is completed, age at 75 °C for 20 min to obtain the suspension.

[0099] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 160°C and held for 2 hours. The temperature is then raised to 220°C and held for 16 hours. The temperature is then raised to 320°C and held for 2 hours. The dehydrogenation catalyst C6 is obtained by calcination, wherein SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0100] Example 7

[0101] (1) Weigh 233.8g of Cu(NO3)2 and 583g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution, take 0.5L of Cu-Zn mixed solution, weigh 87.5g of sodium hydroxide to prepare 1L of alkaline solution, and add the two in parallel to a stirred reactor containing 1L of deionized water at 65℃ to obtain a suspension containing Cu(OH)2 and Zn(OH)2 seed crystals;

[0102] (2) Weigh 195g of orthosilicic acid and add it to 1L of alkaline solution prepared with 80g of NaOH. After etching for 30min, a silicate solution is obtained.

[0103] (3) Add the remaining 1.5 L Cu-Zn mixed solution to the silicate solution in step (2), mix evenly, and then add it in parallel with 3 L of alkaline solution prepared with 262.5 g sodium hydroxide to the seed suspension in step (1) under the action of ultrasound. Adjust the final pH to 7. After the reaction is completed, age at 75°C for 20 min to obtain the suspension.

[0104] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 160°C and held for 2 hours. The temperature is then raised to 220°C and held for 16 hours. The temperature is then raised to 320°C and held for 2 hours. The dehydrogenation catalyst C7 is obtained by calcination, wherein SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0105] Example 8

[0106] The method of Example 1 is different in that, in step (1), 2695.5g of Cu(NO3)2 is weighed and dissolved in 2L of deionized water to prepare Cu ion solution. The other conditions are the same as in Example 1 to obtain dehydrogenation catalyst C8, wherein SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0107] Example 9

[0108] (1) Weigh 233.8g of Cu(NO3)2 and dissolve it in 1L of deionized water to prepare a copper ion solution. Weigh 75g of sodium hydroxide to prepare 1L of alkaline solution. Add the two solutions in parallel at 55℃ to a stirred reactor containing 1L of deionized water to obtain a suspension containing Cu(OH)2 seeds.

[0109] (2) Weigh 260g of silicic acid and add it to 1L of alkaline solution prepared with 100g of NaOH. After etching for 20min, a silicate solution is obtained.

[0110] (3) Weigh 2466.7g of Zn(NO3)2 and dissolve it in 1L of deionized water to prepare a zinc ion solution. Add it to the silicate solution in step (2). After mixing evenly, add it to the suspension containing seed crystals in step (1) in parallel with 3L of alkaline solution prepared with 225g of sodium hydroxide under the action of ultrasound. Adjust the final pH to 7 and age it at 65℃ for 30min to obtain the suspension.

[0111] Under the same conditions as in Example 1, a dehydrogenation catalyst C9 was obtained, wherein the SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0112] Example 10

[0113] (1) Weigh 466.7g of Zn(NO3)2 and dissolve it in 1L of deionized water to prepare a zinc ion solution. Weigh 75g of sodium hydroxide and prepare 1L of alkaline solution. Add the two solutions in parallel at 55℃ to a stirred reactor containing 1L of deionized water to obtain a suspension containing Zn(OH)2 seeds.

[0114] (2) Weigh 260g of silicic acid and add it to 1L of alkaline solution prepared with 100g of NaOH. After etching for 20min, a silicate solution is obtained.

[0115] (3 Weigh out 233.8g of Cu(NO3)2, dissolve it in 1L of deionized water to prepare a copper ion solution, add it to the silicate solution in step (2), mix it evenly, and then add it in parallel with 3L of alkaline solution prepared with 225g of sodium hydroxide under the action of ultrasound to the suspension containing seed crystals in step (1), adjust the final pH to 7, and age it at 65℃ for 30min to obtain the suspension.

[0116] Under the same conditions as in Example 1, a dehydrogenation catalyst C10 was obtained, wherein the SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0117] Example 11

[0118] (1) Weigh 233.8g of Cu(NO3)2 and 466.7g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution. Take 1.5L of Cu-Zn mixed solution, weigh 225g of sodium hydroxide to prepare 1L of alkaline solution, and add the two in parallel to a stirred reactor containing 1L of deionized water at 55℃ to obtain a suspension containing Cu(OH)2 and Zn(OH)2 seed crystals.

[0119] (2) Weigh 260g of silicic acid and add it to 1L of alkaline solution prepared with 100g of NaOH. After etching for 20min, a silicate solution is obtained.

[0120] (3) Add the remaining 0.5 L Cu-Zn mixed solution to the silicate solution in step (2), mix evenly, and then add it in parallel with 3 L of alkaline solution prepared with 75 g sodium hydroxide under the action of ultrasound to the seed suspension in step (1), adjust the final pH to 7, and age at 65 °C for 30 min to obtain the suspension.

[0121] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 140°C and held for 4 hours. The temperature is then raised to 250°C and held for 12 hours. The temperature is then raised to 320°C and held for 4 hours. The calcination yields the dehydrogenation catalyst C11, wherein SiO2 in the catalyst shell is a chain-like silicon-oxygen tetrahedron.

[0122] Examples 12-22

[0123] The catalyst was applied to the dehydrogenation of cyclohexanol to cyclohexanone.

[0124] (1) Take 50 ml of C1-C11 catalyst and fill it into a fixed bed reactor in layers. Perform segmented reduction activation on the catalyst. Raise the temperature from room temperature to 120℃ and hold for 4 h. Continue to raise the temperature to 180℃ and pass 5% H2 for 8 h. Raise the temperature to 210℃ and gradually increase the H2 concentration to all hydrogen. Hold for 4 h to complete the activation.

[0125] (2) Reaction temperature 210℃, reaction pressure atmospheric pressure, cyclohexanol liquid hourly space velocity 1.0 h⁻¹ -1 The cyclohexanol reaction was carried out at a flow rate of 400 ml / min using N2.

[0126] Comparative Example 1

[0127] A commercially available Cu-Si cyclohexanol dehydrogenation catalyst was used, and the Cu-Si catalyst was prepared by milling. The catalyst was evaluated according to the evaluation method of Example 12, and the reaction results are as follows:

[0128] In the initial stage of the reaction, the conversion rate of cyclohexanol was 58%, and the selectivity of cyclohexanone was 99.1%.

[0129] After 500 hours of reaction, the conversion rate of cyclohexanol was 54%, and the selectivity of cyclohexanone was 98.8%.

[0130] Comparative Example 2

[0131] (1) Weigh 233.8g of Cu(NO3)2 and 466.7g of Zn(NO3)2, dissolve them in 2L of deionized water to prepare a Cu-Zn mixed solution. Take 0.5L of Cu-Zn mixed solution, weigh 75g of sodium hydroxide to prepare 1L of alkaline solution, and add the two solutions in parallel to a stirred reactor containing 1L of deionized water at 55℃ to obtain a seed solution of Cu(OH)2 and Zn(OH)2.

[0132] (2) Weigh 260g of silicic acid and add it to 1L of water to obtain a turbid liquid;

[0133] (3) Add the remaining 1.5 L Cu-Zn mixed solution to the turbid liquid in step (2), mix evenly, and then add it in parallel with 3 L of alkaline solution prepared with 225 g sodium hydroxide under the action of ultrasound to the seed solution of Cu(OH)2 and Zn(OH)2. Adjust the final pH to 7, and age at 65℃ for 30 min to obtain a suspension.

[0134] (4) The suspension in step (3) is filtered, washed, dried, and then calcined in stages. The temperature is raised from room temperature to 140°C and held for 4 hours. The temperature is then raised to 250°C and held for 12 hours. The temperature is then raised to 320°C and held for 4 hours. The dehydrogenation catalyst is obtained by calcination. In the catalyst shell, SiO2 is a three-dimensional network silicon-oxygen tetrahedron.

[0135] The catalyst was evaluated according to the evaluation method of Example 12, and the reaction results are as follows:

[0136] In the initial stage of the reaction, the conversion rate of cyclohexanol was 59%, and the selectivity of cyclohexanone was 99.84%.

[0137] After 500 hours of reaction, the conversion rate of cyclohexanol was 56%, and the selectivity of cyclohexanone was 99.81%.

[0138] Table 1

[0139]

[0140]

[0141] As can be seen from the data in Table 1, when the catalyst designed by the technical solution of this invention is applied to the reaction of cyclohexanol oxidation to cyclohexanone, the conversion rate of cyclohexanol reaches more than 63%, and the selectivity of cyclohexanol reaches more than 99.8%, demonstrating excellent catalyst performance.

[0142] Example 23

[0143] The C1 catalyst was loaded into a fixed-bed reactor in accordance with the method of Example 12. The reaction temperature and liquid hourly space velocity were changed, and a 500-hour life test was conducted. The results are shown in Table 2.

[0144] Table 2

[0145]

[0146] As can be seen from Table 2, at a reaction temperature of 200℃-250℃, the liquid hourly space velocity is 1.0-1.5 h⁻¹. -1 At nitrogen flow rates of 400-600 ml / min, the catalyst exhibits excellent catalytic performance. The catalyst also demonstrates excellent stability and is suitable for high-load cyclohexanol industrial reaction conditions, which is conducive to industrial application.

[0147] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A dehydrogenation catalyst, characterized in that, The catalyst comprises a core and a shell covering the core; the core is a first dehydrogenation active component oxide, and the shell is SiO2 doped with a second dehydrogenation active component oxide; the SiO2 has a chain-like silicon-oxygen tetrahedral structure. The first dehydrogenation active component and the second dehydrogenation active component are each selected from copper and / or zinc; Based on the total weight of the active component oxides, the content of the first dehydrogenation active component oxide is 15-45% by weight, and the content of the second dehydrogenation active component oxide is 15-60% by weight. The catalyst has a specific surface area of ​​235-450 m². 2 / g, with a pore size of 25-48nm.

2. The dehydrogenation catalyst according to claim 1, wherein, By mass ratio, the total content of the first dehydrogenation active component oxide and the second dehydrogenation active component oxide in the dehydrogenation catalyst is 60wt%-80wt%, and the SiO2 content is 20wt%-40wt%. and / or The content of the first dehydrogenation active component oxide is 15-20% by weight; the content of the second dehydrogenation active component oxide is 45-60% by weight.

3. The dehydrogenation catalyst according to claim 1 or 2, wherein, The first dehydrogenation active component is copper, and the second dehydrogenation active component is zinc.

4. The method for preparing the dehydrogenation catalyst according to any one of claims 1-3, characterized in that, The method includes: (1) Mix the solution containing the first dehydrogenation active component source with an alkaline solution and react to obtain a suspension containing the first dehydrogenation active component seed crystals; (2) Add SiO2 source to alkaline solution for etching to obtain silicate solution; (3) Mix the silicate solution in step (2) with the solution containing the second dehydrogenation active component source, and then add it in parallel with the alkaline solution to the suspension containing the first dehydrogenation active component seed crystal in step (1), control the pH to 7-9, and carry out aging; (4) The suspension obtained by aging is separated to obtain a precipitate, which is then washed, dried and calcined to obtain a dehydrogenation catalyst.

5. The preparation method according to claim 4, wherein, In step (1), the reaction temperature is 50-70℃; and / or In step (1), the concentration of the first dehydrogenation active component ion in the solution containing the first dehydrogenation active component source is 0.5-2.5 mol / L; the concentration of hydroxide ions in the alkaline solution is 1.5-2.5 mol / L; the molar ratio of the first dehydrogenation active component ion to hydroxide ions is 1:2-3; and / or In step (2), the SiO2 source is calculated as SiO2, the molar ratio of SiO2 to hydroxide ions in the alkaline solution is 1-2.5:1, and the hydroxide ion concentration in the alkaline solution is 1.25-2.5 mol / L; and / or In step (2), etching takes 10-60 minutes.

6. The preparation method according to claim 4 or 5, wherein, In step (3), the mixture is flowed in parallel under the action of ultrasound; and / or In step (3), the concentration of active component ions in the solution containing the second dehydrogenation active component source is 0.5-2.5 mol / L; and / or In step (3), the hydroxide ion concentration in the alkaline solution is 1.25-2.5 mol / L; and / or In step (3), the mass ratio of the silicate solution to the second dehydrogenation active component source solution is 0.2-2:1; and / or In step (3), the aging conditions include: a temperature of 60-80℃ and a time of 20-60 min; and / or In step (4), the roasting conditions include: roasting temperature of 140-350℃ and roasting time of 12-24h.

7. The preparation method according to claim 6, wherein, The frequency of ultrasound is 40-80KHz.

8. The preparation method according to claim 4 or 5, wherein, The first and second dehydrogenation active component sources are each independently selected from at least one soluble metal salt of the dehydrogenation active component; and / or The SiO2 source is selected from at least one of silicic acid, tetraethyl orthosilicate, silica sol, and silica fume; and / or The alkali is selected from potassium hydroxide and / or sodium hydroxide.

9. The preparation method according to claim 8, wherein, The first dehydrogenation active component source and the second dehydrogenation active component source are each selected from at least one of nitrate, hydrochloride and sulfate.

10. The use of the dehydrogenation catalyst according to any one of claims 1-3 in the dehydrogenation of alcohols to ketones.

11. A method for preparing cyclohexanone, wherein, The method includes: (I) The dehydrogenation catalyst is reduced in a reducing gas atmosphere; (II) In the presence of the catalyst obtained in step (I), cyclohexanol is vaporized using N2 as a carrier gas to dehydrogenate cyclohexanol to produce cyclohexanone; The dehydrogenation catalyst includes the dehydrogenation catalyst according to any one of claims 1-3.

12. The preparation method according to claim 11, wherein, In step (I), the reduction conditions include: a temperature of 120-230℃ and a time of 12-24h; and / or In step (II), the dehydrogenation conditions include: a temperature of 200-250℃, a pressure of 0.1-0.3 MPa, and a cyclohexanol space velocity of 1.0-1.5 h⁻¹. -1 The N2 flow rate is 400-600 ml / min.

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