Process for the preparation of a catalyst, catalyst and process for the synthesis of nitrogen-containing heterocyclic compounds by dehydrogenation of diphenylamine

Abstract

The present application relates to the technical field of catalyst preparation, and discloses a catalyst preparation method, a catalyst and a method for synthesizing nitrogen-containing heterocyclic compounds by diphenylamine dehydrogenation, the preparation method comprising: (1) contacting a first modification liquid comprising a silicon source and a first solvent with an alumina carrier to perform first modification treatment, and then performing first calcination to obtain a first precursor; (2) contacting a second modification liquid comprising an organic amine and a second solvent with the first precursor to perform second modification treatment, and then performing second calcination to obtain a second precursor; (3) loading an active metal component and an optional auxiliary component on the second precursor, and then performing third calcination; wherein the active metal component is Pt, and the auxiliary component is selected from at least one of Fe, Mo and P. The catalyst prepared by the preparation method is used in the reaction of synthesizing nitrogen-containing heterocyclic compounds by diphenylamine dehydrogenation, and has high reactivity and selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to a method for preparing a catalyst and a method for synthesizing nitrogen-containing heterocyclic compounds by dehydrogenation of a catalyst and diphenylamine. Background Technology

[0002] Carbazole, also known as iminodiphenylene or 9-azafluorene, is a nitrogen-containing heterocyclic compound and one of the most economically valuable components of coal tar. Carbazole is an important raw material for the synthesis of dyes and pigments, and can be used as a stabilizer for insecticides and a plant growth regulator, or in the synthesis of insecticides. In addition, carbazole is a high-performance polymer material and rubber modifier, and can be used to synthesize special materials to meet specific needs, such as high-tech materials that conduct electricity and light, and high-frequency electrical insulation materials with heat resistance. Recent research shows that carbazole compounds have inhibitory effects and can be used to synthesize antitumor, antifungal, antihypertensive, cardiotonic, and novel chemotherapy antiemetic drugs.

[0003] Extensive research has been conducted on the synthesis process of carbazole in the prior art. However, current synthesis processes all require the introduction of large amounts of organic solvents, leading to high costs for subsequent product separation and purification. CN115215784A discloses a process for synthesizing carbazole using N-phenylaniline as a raw material, synthesizing high-purity carbazole under the combined action of a metal catalyst and an oxidant. However, the precious metal solution used in this process is difficult to recover, and the use of organic solvents increases the difficulty of subsequent separation, raising production costs. CN115215785A discloses a carbazole synthesis process using diphenylamine as a reaction substrate, adding oxygen, palladium acetate, glacial acetic acid, butyric acid, and ethanol at a reaction temperature of 90℃ and a reaction pressure of 0.7MPa, reacting for 2 hours, and obtaining carbazole compounds after sublimation purification. This process also suffers from the problems of difficult recovery of the precious metal palladium catalyst solution and the need for large amounts of organic solvents. CN104043467A discloses a catalyst and preparation method for carbazole. The catalyst is composed of inorganic salts of alkali metals, phosphorus pentoxide, and oxides of transition metals such as V, Fe, and Ni. In this reaction process, high-temperature steam flowing from a fixed bed is passed through cooling water to dissolve the reactants. The feed conversion rate reaches over 91% and the selectivity over 92% in small-scale trials. However, the process requires a relatively high reaction temperature, which shortens the catalyst's lifespan. The use of steam increases energy consumption, thereby raising separation costs.

[0004] Therefore, the extensive use of organic solvents in the synthesis process of existing technologies leads to relatively high costs and serious pollution in the subsequent product separation and purification. Furthermore, the preparation of catalysts in existing technologies suffers from high noble metal loading, low dispersion, and low utilization, resulting in relatively high catalyst costs and relatively low activity. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low metal utilization and insufficient catalyst activity in the prior art, and to provide a method for preparing a catalyst and a method for synthesizing nitrogen-containing heterocyclic compounds by dehydrogenation of the catalyst and diphenylamine. The catalyst prepared by this method has the characteristics of high utilization of active components, high catalytic activity and good stability.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0007] (1) The first modified liquid is brought into contact with the alumina carrier for the first modification treatment, and then the first calcination is performed to obtain the first precursor.

[0008] The first modified liquid comprises a silicon source and a first solvent; the mass ratio of the silicon source to the alumina support, calculated as SiO2, is (0.01-0.5):1;

[0009] (2) The second modified liquid is brought into contact with the first precursor to perform a second modification treatment, and then a second calcination is performed to obtain the second precursor;

[0010] The second modified liquid includes an organic amine and a second solvent, and the mass ratio of the second modified liquid to the alumina carrier, based on the mass of the organic amine, is (0.5-2):1.

[0011] (3) Load the active metal component and optional auxiliary component onto the second precursor, and then perform a third calcination;

[0012] The active metal component is Pt, and the auxiliary component is selected from at least one of Fe, Mo and P.

[0013] A second aspect of the present invention provides a catalyst prepared by the above-described preparation method;

[0014] The catalyst includes a support and an active component and an optional auxiliary component supported on the support; the active metal component is Pt, and the auxiliary component is selected from at least one of Fe, Mo and P.

[0015] A third aspect of the present invention provides a method for synthesizing a nitrogen-containing heterocyclic compound by dehydrogenation of diphenylamine, the method comprising: contacting diphenylamine with a dehydrogenation catalyst under dehydrogenation reaction conditions;

[0016] The dehydrogenation catalyst is the catalyst described in the second aspect.

[0017] The inventors of this invention discovered that a high acidity level on the surface of the alumina support easily leads to catalyst coking or the formation of large molecules. These carbon deposits eventually clog the pores of the catalyst, causing catalyst deactivation and affecting its single-pass lifespan. Simultaneously, a high acidity level on the alumina support surface easily induces the cracking reaction of diphenylamine, reducing the catalyst's selectivity.

[0018] The catalyst preparation method provided by this invention modifies the alumina support, causing silicon molecules to interact with acidic sites on the alumina support surface, resulting in partial dehydroxylation and dealuminization of the alumina support to replenish silicon. This regulates the number and intensity distribution of acidic sites on the alumina support surface. By treating the catalyst support with silicon and pretreating it with organic amine solution, the dispersion of noble metals can be significantly improved, the utilization rate of noble metals can be increased, the carbon deposition rate of the catalyst can be reduced, the isomerization reaction on the catalyst surface can be inhibited, and the activity and selectivity of the catalyst can be improved.

[0019] The catalyst prepared by the method provided in this invention exhibits high reactivity and high selectivity in the dehydrogenation synthesis of nitrogen-containing heterocyclic compounds from diphenylamine under mild reaction conditions. This method is characterized by mild conditions, simple operation, and suitability for industrial-scale production. Detailed Implementation

[0020] 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.

[0021] The first aspect of this invention provides a method for preparing a catalyst, comprising the following steps:

[0022] (1) The first modified liquid is brought into contact with the alumina carrier for the first modification treatment, and then the first calcination is performed to obtain the first precursor.

[0023] The first modified liquid comprises a silicon source and a first solvent; the mass ratio of the silicon source to the alumina support, calculated as SiO2, is (0.01-0.5):1;

[0024] (2) The second modified liquid is brought into contact with the first precursor to perform a second modification treatment, and then a second calcination is performed to obtain the second precursor;

[0025] The second modified liquid includes an organic amine and a second solvent, and the mass ratio of the second modified liquid to the alumina carrier, based on the mass of the organic amine, is (0.5-2):1.

[0026] (3) Load the active metal component and optional auxiliary component onto the second precursor, and then perform a third calcination;

[0027] The active metal component is Pt, and the auxiliary component is selected from at least one of Fe, Mo and P.

[0028] According to the present invention, by subjecting the alumina support to a first modification treatment (silicon treatment) and a second modification treatment (organic amine solution pretreatment), on the one hand, the dispersion of the active metal component and the auxiliary component can be significantly improved, the utilization rate of precious metals can be increased, and the preparation cost of the catalyst can be reduced. On the other hand, the high acidity on the surface of the alumina support easily causes diphenylamine to undergo a cracking reaction, which is detrimental to the selectivity of the catalyst. The preparation method provided by the present invention modifies the alumina support so that silicon molecules interact with the acidic sites on the surface of the alumina support, resulting in partial dehydroxylation and dealuminization of the alumina support to replenish silicon, thereby adjusting the number and intensity distribution of acidic sites on the surface of the alumina support. At the same time, it is beneficial to the desorption of carbazole compounds on the catalyst surface, thereby reducing the carbon deposition rate of the catalyst, inhibiting the isomerization reaction on the catalyst surface, and improving the activity and selectivity of the catalyst.

[0029] The present invention does not particularly limit the alumina support, which can be commercially available or prepared using any method known in the art. Preferably, the specific surface area of ​​the alumina support is 180-230 m². 2 / g, with a pore size of 15-20nm. Using the above-mentioned preferred alumina support can further improve the activity of the prepared catalyst.

[0030] According to the present invention, there is no particular limitation on the contact method between the first modification treatment and the second modification treatment, and conventional methods in the art can be used. For example, the first modification treatment can be carried out by impregnating an alumina carrier with a first modified liquid.

[0031] The present invention does not particularly limit the conditions of the first modification treatment, as long as the first modification liquid is in full contact with the alumina carrier. Preferably, the temperature of the first modification treatment is 30-100℃, more preferably 30-70℃, and the time is 1-8h, more preferably 2-6h.

[0032] Preferably, the first modification treatment is carried out under stirring conditions. The present invention does not have a particular limitation on the stirring speed, but it is based on ensuring that the first modified liquid and the alumina carrier are in full contact. Those skilled in the art can select according to actual needs.

[0033] According to the present invention, step (1) further includes: performing solid-liquid separation and drying on the product obtained from the first modification treatment to remove residual liquid on the surface of the solid product. The present invention does not particularly limit the method of solid-liquid separation; conventional methods in the art can be used, such as filtration or centrifugation. Preferably, the drying can be carried out in an oven at a temperature of 70-150°C for 1-24 hours.

[0034] According to some preferred embodiments of the present invention, the conditions for the first calcination include: a temperature of 250-750°C, preferably 450-650°C, and a time of 0.5-10 h, preferably 3-6 h.

[0035] According to the present invention, the mass ratio of the silicon source to the alumina support, calculated as SiO2, is (0.01-0.5):1, preferably (0.01-0.2):1, more preferably 0.03-0.05:1, and for example, it can be a specific mass ratio or any range between the two, such as 0.03:1, 0.035:1, 0.04:1, 0.045:1, 0.05:1. Controlling the amount of silicon source in the first modification solution within the above range is beneficial for adjusting the number and intensity distribution of acidic sites on the surface of the alumina support, further improving the activity and stability of the catalyst.

[0036] According to some preferred embodiments of the present invention, the volume ratio of silicon source to first solvent is 1:(10-200), preferably 1:(15-120).

[0037] The present invention has a wide range of choices for the silicon source. Preferably, the silicon source is an organosilicon, such as an organosilicon and / or a silicate ester, more preferably at least one of tetraethyl silicate, methyltriethoxysilane, trimethylchlorosilane, propyltriethoxysilane, tetrachlorosilane and aminosilane, and more preferably tetraethyl silicate.

[0038] The present invention does not have a particular limitation on the type of the first solvent, as long as it can dissolve the silicon source. Those skilled in the art can select it according to actual needs. Preferably, the first solvent is an alcohol solvent, preferably a C1-C6 fatty alcohol, such as at least one of methanol, ethanol, propanol, butanol, glycerol and isopropanol, preferably ethanol.

[0039] According to the present invention, preferably, the second modification treatment includes impregnating the first precursor with a second modifying liquid.

[0040] The present invention does not particularly limit the conditions for the second modification treatment, as long as the second modification liquid is in full contact with the first precursor. Preferably, the temperature of the second modification treatment is 30-100℃, more preferably 30-70℃, and the time is 1-8h, more preferably 2-6h.

[0041] According to the present invention, the volume ratio of the organic amine and the second solvent is 1:(1-10), preferably 1:(2-8).

[0042] According to some preferred embodiments of the present invention, the mass ratio of the second modified liquid to the alumina carrier, based on the mass of organic amine, is (0.5-2):1, preferably (0.8-1.2):1, and can be, for example, specific mass ratios such as 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, or any range between the two.

[0043] According to the present invention, preferably, the conditions for the second calcination include: a temperature of 250-750°C, more preferably 450-650°C, and a time of 0.5-10h, more preferably 3-6h.

[0044] In this invention, the range of organic amines is relatively wide. Preferably, the organic amine is a monohydric or polyhydric amine, and more preferably, it is at least one of n-propanolamine, ethanolamine, triethanolamine, diethanolamine, isopropanolamine, isobutanolamine, and n-butanolamine.

[0045] The present invention does not have any particular limitation on the type of the second solvent, but it is based on the ability to fully dissolve the organic amine. The selection range of the second solvent can be the same as that of the first solvent.

[0046] According to the present invention, step (2) further includes: performing solid-liquid separation and drying on the product obtained from the second modification treatment to remove residual liquid on the surface of the solid product. The present invention does not particularly limit the method and conditions of the solid-liquid separation and drying, and they can be the same as those described above, and will not be repeated here.

[0047] According to the present invention, in step (3), the active metal component and optional auxiliary component can be loaded onto the second precursor in any conventional manner in the art. Those skilled in the art can make the selection according to actual needs. Preferably, the mass ratio of the active metal component and the auxiliary component is 1:(0.1-10) in terms of elements, preferably 1:(1.5-6), for example, it can be a specific mass ratio or a range between the two such as 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:5, 1:6, etc.

[0048] According to the present invention, preferably, the method of loading the active metal component and optional auxiliary component onto the second precursor in step (3) includes: impregnating the second precursor with an impregnation solution containing the active metal component precursor and optional auxiliary component precursor, and then drying it.

[0049] Impregnation is a widely used catalyst preparation method in industry due to its simplicity and relatively low cost. However, the concentration of the impregnation solution must be properly controlled when preparing noble metal catalysts using this method. If the solution concentration is too high, the active components are not easily adsorbed into the catalyst pores, resulting in uneven distribution of the active components on the support. Therefore, in conventional impregnation loading processes, the impregnation solution concentration is limited, making it difficult to simultaneously achieve the desired metal loading and dispersion. The inventors of this invention discovered that pretreating a porous alumina support after silicon treatment with an organic amine solution can effectively improve the dispersion of the noble metal Pt, increase its utilization rate, and thus improve the catalyst's lifespan and reactivity.

[0050] In this invention, the concentration of the impregnation solution can be selected within a wide range to meet different metal loading requirements. Preferably, the concentration of the impregnation solution is 0.01-0.2 mol / L, more preferably 0.02-0.1 mol / L. In this invention, the concentration of the impregnation solution refers to the total concentration of the active metal component and the auxiliary component in the impregnation solution.

[0051] According to the present invention, preferably, the drying temperature is 100-120°C and the time is 2-6 hours.

[0052] This invention does not particularly limit the specific types of the active metal component precursor and the auxiliary component precursor, and can use conventional choices in the art. For example, the precursor of the active metal Pt can be any one of platinum nitrate, oxalate, acetate, or chloride. The precursor of the auxiliary component can be selected from any organic or inorganic salt containing the auxiliary component. For example, the precursor of Fe can be any one of Fe carbonate, nitrate, oxalate, acetate, or chloride; the precursor of Mo can be, for example, ammonium molybdate; and the precursor of P can be, for example, phosphate, such as sodium hypophosphite.

[0053] According to the present invention, preferably, the conditions for the third calcination include: a temperature of 250-750°C, more preferably 450-650°C, and a time of 0.5-10h, more preferably 3-6h.

[0054] According to the present invention, the preparation method further includes: reducing the product obtained from the third calcination under hydrogen conditions. It is understood that the reduction treatment can be carried out during catalyst preparation or before the catalyst is applied in the corresponding reaction; those skilled in the art can choose according to actual needs.

[0055] Preferably, the conditions for the reduction treatment include: a temperature of 200-600℃, more preferably 300-500℃; a hydrogen pressure of 0-0.1MPa, more preferably 0.01-0.05MPa; and a time of 1-10h, more preferably 3-6h.

[0056] A second aspect of the present invention provides a catalyst prepared by the above-described preparation method; the catalyst includes a support and an active component and an optional auxiliary component supported on the support; the active metal component is Pt, and the auxiliary component is selected from at least one of Fe, Mo and P.

[0057] By modifying the alumina support, partial dehydroxylation and dealuminization of the alumina support are achieved, thereby adjusting the number and intensity distribution of acidic sites on the alumina support surface.

[0058] In this invention, the total acidity of the catalyst is obtained by NH3-TPD analysis.

[0059] According to the present invention, preferably, based on the total amount of the catalyst, the content of the active metal component is 0.1-5 wt%, more preferably 0.1-2 wt%, and even more preferably 0.2-1 wt%, and the content of the auxiliary component is 0.1-10 wt%, more preferably 0.1-3 wt%, and even more preferably 1-2 wt%.

[0060] In this invention, the elemental composition of the catalyst is determined by ICP analysis.

[0061] A third aspect of the present invention provides a method for synthesizing a nitrogen-containing heterocyclic compound by dehydrogenation of diphenylamine, the method comprising: contacting diphenylamine with a dehydrogenation catalyst under dehydrogenation reaction conditions, wherein the dehydrogenation catalyst is the catalyst described in the second aspect.

[0062] According to some preferred embodiments of the present invention, the conditions for the dehydrogenation reaction include: a temperature of 250-400°C, preferably 255-355°C; a pressure of 0-0.1 MPa, preferably 0-0.01 MPa; and a liquid hourly space velocity of 0.1-0.5 g·gcat. -1 ·h -1 The preferred concentration is 0.2-0.4 g·gcat. -1 ·h -1 In this invention, unless otherwise specified, all pressures referred to are gauge pressures.

[0063] According to the present invention, preferably, the contact is carried out in the presence of a carrier gas, which can be any conventional inert gas in the art, such as nitrogen. Preferably, the molar ratio of nitrogen to diphenylamine is (1-50):1, and more preferably (10-30):1.

[0064] Preferably, no organic solvent is required during the contact process.

[0065] In this invention, if no reduction is performed during catalyst preparation, the method preferably further includes a step of reducing the catalyst under hydrogen conditions. The specific operating conditions have been described in detail above and will not be repeated here.

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

[0067] Unless otherwise specified, the raw materials used in the following examples are all commercially available.

[0068] The alumina carrier used in the following examples was purchased from Shandong Branch of Aluminum Corporation of China, with a specific surface area of ​​197 m². 2 / g, pore size 16nm. The ferric nitrate used is ferric nitrate nonahydrate, commercially available. The Pt content in chloroplatinic acid is 38wt%.

[0069] Example 1

[0070] (1) Mix 1.5 mL of tetraethyl silicate and 48.5 mL of ethanol in a round-bottom flask to obtain the first modified solution. Add 10 g of alumina support (the mass ratio of the silicon source to the alumina support, calculated as SiO2, is about 0.04:1). Turn on the magnetic stirrer and stir the material in the round-bottom flask at 30°C for 4 h. Filter the product and dry it in an oven at 120°C for 2 h. Then, place the dried support in a muffle furnace and calcine it at 550°C for 4 h to obtain the first precursor.

[0071] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h (the mass ratio of ethanolamine to alumina support was approximately 1:1). After that, it was filtered and dried in an oven. Then the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0072] (3) Weigh 0.104 g of chloroplatinic acid, 1.085 g of ferric nitrate and 9.92 g of deionized water, prepare them into a nitrate mixture, and then place the second precursor in it and impregnate it at 30 °C for 2 h. After impregnation, place the catalyst precursor in an oven at 120 °C and dry it for 2 h. Then place it in a muffle furnace and calcine it at 550 °C for 4 h to obtain catalyst CAT-1. NH3-TPD analysis of catalyst CAT-1 showed that the total acid content was 0.254 mmol / g.

[0073] ICP analysis revealed that the catalyst contained 0.38 wt% Pt and 1.52 wt% Fe.

[0074] Example 2

[0075] (1) 1.2 mL of tetraethyl silicate and 48.8 mL of ethanol were mixed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added (the mass ratio of the silicon source to the alumina support, calculated as SiO2, was approximately 0.03:1). Magnetic stirring was turned on, and the material in the round-bottom flask was stirred at 30 °C for 4 h. The product was filtered and dried in an oven at 120 °C for 2 h. Then, the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0076] (2) The first precursor was placed in a round-bottom flask containing 11 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h (the mass ratio of ethanolamine to alumina support was approximately 1.1:1). After that, it was filtered and dried in an oven. Then the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0077] (3) Weigh 0.208g chloroplatinic acid, 1.085g ferric nitrate and 9.92g deionized water and prepare them into a nitrate mixture. Then, place the second precursor in it and impregnate it at 30°C for 2h. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2h. Then, place it in a muffle furnace and calcine it at 550°C for 4h to obtain catalyst CAT-2.

[0078] ICP analysis revealed that the catalyst contained 0.79 wt% Pt and 1.51 wt% Fe.

[0079] Example 3

[0080] (1) 1.8 mL of tetraethyl silicate and 48.2 mL of ethanol were mixed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added (the mass ratio of the silicon source to the alumina support, calculated as SiO2, was approximately 0.05:1). Magnetic stirring was turned on, and the material in the round-bottom flask was stirred at 30 °C for 4 h. The product was filtered and dried in an oven at 120 °C for 2 h. Then, the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0081] (2) The first precursor was placed in a round-bottom flask containing 8 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h (the mass ratio of ethanolamine to alumina support was approximately 0.8:1). After that, it was filtered and dried in an oven. The dried support was then calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0082] (3) Weigh 0.156g chloroplatinic acid, 1.085g ferric nitrate and 9.92g deionized water and prepare them into a nitrate mixture. Then, place the second precursor in it and impregnate it at 30°C for 2h. Then, place the impregnated catalyst precursor in an oven at 120°C and dry it for 2h. Then, place it in a muffle furnace and calcine it at 550°C for 4h to obtain catalyst CAT-3.

[0083] ICP analysis revealed that the catalyst contained 0.6 wt% Pt and 1.5 wt% Fe.

[0084] Example 4

[0085] (1) 1.5 mL of tetraethyl silicate and 48.5 mL of ethanol were placed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added, and magnetic stirring was turned on. The material in the round-bottom flask was stirred at 30 °C for 4 h. The product was then filtered and dried in an oven at 120 °C for 2 h. The dried support was then calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0086] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h. After that, it was filtered and dried in an oven. Then the dried carrier was calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0087] (3) Weigh 0.26g chloroplatinic acid, 1.085g ferric nitrate and 9.92g deionized water and prepare them into a nitrate mixture. Then, place the second precursor in it and impregnate it at 30°C for 2h. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2h. Then, place it in a muffle furnace and calcine it at 550°C for 4h to obtain catalyst CAT-4.

[0088] ICP analysis revealed that the catalyst contained 0.99 wt% Pt and 1.5 wt% Fe.

[0089] Example 5

[0090] (1) Mix 0.5 mL of tetraethyl silicate and 49.5 mL of ethanol in a round-bottom flask to obtain the first modified solution. Add 10 g of alumina support (the mass ratio of the silicon source to the alumina support, calculated as SiO2, is approximately 0.01:1). Turn on the magnetic stirrer and stir the material in the round-bottom flask at 30 °C for 4 h. Filter the product and dry it in an oven at 120 °C for 2 h. Then, calcine the dried support in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0091] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h (the mass ratio of ethanolamine to alumina support was approximately 1:1). After that, it was filtered and dried in an oven. The dried support was then calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0092] (3) Weigh 0.104g chloroplatinic acid, 1.085g ferric nitrate and 9.92g deionized water, prepare them into a nitrate mixture, and then place the second precursor in it and impregnate it at 30℃ for 2h. After impregnation, place the catalyst precursor in an oven at 120℃ and dry it for 2h. Then, calcine it in a muffle furnace at 550℃ for 4h to obtain catalyst CAT-5. NH3-TPD analysis of catalyst CAT-5 showed that the total acid content was 0.272mmol / g.

[0093] ICP analysis revealed that the catalyst contained 0.39 wt% Pt and 1.51 wt% Fe.

[0094] Example 6

[0095] (1) Mix 1 mL of tetraethyl silicate and 49 mL of ethanol in a round-bottom flask to obtain the first modified solution. Then add 10 g of alumina support (the mass ratio of the silicon source to the alumina support, calculated as SiO2, is about 0.03:1). Turn on the magnetic stirrer and stir the material in the round-bottom flask at 30°C for 4 h. After filtration, dry it in an oven at 120°C for 2 h. Then calcine it in a muffle furnace at 550°C for 4 h to obtain the first precursor.

[0096] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h (the mass ratio of ethanolamine to alumina support was approximately 1:1). After that, it was filtered and dried in an oven. The dried support was then calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0097] (3) Weigh 0.104 g of chloroplatinic acid, 1.085 g of ferric nitrate and 9.92 g of deionized water and prepare them into a nitrate mixture. Then, place the second precursor in it and impregnate it at 30 °C for 2 h. After impregnation, place the catalyst precursor in an oven at 120 °C and dry it for 2 h. Then, calcine it in a muffle furnace at 550 °C for 4 h to obtain catalyst CAT-6. NH3-TPD analysis of catalyst CAT-6 showed that the total acid content was 0.261 mmol / g.

[0098] ICP analysis revealed that the catalyst contained 0.4 wt% Pt and 1.49 wt% Fe.

[0099] Example 7

[0100] (1) 2 mL of tetraethyl silicate and 48 mL of ethanol were mixed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added (the mass ratio of the silicon source to the alumina support, calculated as SiO2, was approximately 0.05:1). Magnetic stirring was turned on, and the material in the round-bottom flask was stirred at 30 °C for 4 h. The product was filtered and dried in an oven at 120 °C for 2 h. Then, the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0101] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h (the mass ratio of ethanolamine to alumina support was approximately 1:1). After that, it was filtered and dried in an oven. Then the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0102] (3) Weigh 0.104 g of chloroplatinic acid, 1.085 g of ferric nitrate and 9.92 g of deionized water, and prepare a nitrate mixture. Then, place the second precursor in the mixture and impregnate it at 30 °C for 2 h. After impregnation, dry the catalyst precursor in an oven at 120 °C for 2 h, and then calcine it in a muffle furnace at 550 °C for 4 h to obtain catalyst CAT-7. NH3-TPD analysis of catalyst CAT-7 showed a total acid content of 0.246 mmol / g.

[0103] ICP analysis revealed that the catalyst contained 0.39 wt% Pt and 1.5 wt% Fe.

[0104] Example 8

[0105] (1) 2.5 mL of tetraethyl silicate and 47.5 mL of ethanol were mixed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added (the mass ratio of the silicon source to the alumina support, calculated as SiO2, was approximately 0.07:1). Magnetic stirring was turned on, and the material in the round-bottom flask was stirred at 30 °C for 4 h. The product was filtered and dried in an oven at 120 °C for 2 h. Then, the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0106] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h (the mass ratio of ethanolamine to alumina support was approximately 1:1). After that, it was filtered and dried in an oven. The dried support was then calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0107] (3) Weigh 0.104 g of chloroplatinic acid, 1.085 g of ferric nitrate and 9.92 g of deionized water, prepare them into a nitrate mixture, and then place the second precursor in it and impregnate it at 30 °C for 2 h. After impregnation, place the catalyst precursor in an oven at 120 °C and dry it for 2 h. Then calcine it in a muffle furnace at 550 °C for 4 h to obtain catalyst CAT-8. NH3-TPD analysis of catalyst CAT-8 showed that the total acid content was 0.232 mmol / g.

[0108] ICP analysis revealed that the catalyst contained 0.42 wt% Pt and 1.48 wt% Fe.

[0109] Example 9

[0110] (1) 1.5 mL of tetraethyl silicate and 48.5 mL of ethanol were mixed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added (the mass ratio of the silicon source to the alumina support, calculated as SiO2, was approximately 0.04:1). Magnetic stirring was turned on, and the material in the round-bottom flask was stirred at 30 °C for 4 h. The product was filtered and dried in an oven at 120 °C for 2 h. Then, the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0111] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h (the mass ratio of ethanolamine to alumina support was approximately 1:1). After that, it was filtered and dried in an oven. Then the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0112] (3) Weigh 0.052g chloroplatinic acid, 1.085g ferric nitrate and 9.92g deionized water and prepare them into a nitrate mixture. Then, place the second precursor in it and impregnate it at 30°C for 2h. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2h. Then, calcine it in a muffle furnace at 550°C for 4h to obtain catalyst CAT-9.

[0113] ICP analysis revealed that the catalyst contained 0.21 wt% Pt and 1.49 wt% Fe.

[0114] Example 10

[0115] (1) 1.5 mL of tetraethyl silicate and 48.5 mL of ethanol were mixed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added, and magnetic stirring was turned on. The material in the round-bottom flask was stirred at 30 °C for 4 h. The product was filtered and dried in an oven at 120 °C for 2 h. Then the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0116] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h. After that, it was filtered and dried in an oven. Then the dried carrier was calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0117] (3) Weigh 0.26g chloroplatinic acid, 0.723g ferric nitrate and 9.92g deionized water and prepare them into a nitrate mixture. Then, place the second precursor in it and impregnate it at 30°C for 2h. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2h. Then, calcine it in a muffle furnace at 550°C for 4h to obtain catalyst CAT-10.

[0118] ICP analysis revealed that the catalyst contained 1.01 wt% Pt and 0.99 wt% Fe.

[0119] Example 11

[0120] (1) 1.5 mL of tetraethyl silicate and 48.5 mL of ethanol were mixed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added, and magnetic stirring was turned on. The material in the round-bottom flask was stirred at 30 °C for 4 h. The product was then filtered and dried in an oven at 120 °C for 2 h. The dried support was then calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0121] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h. After that, it was filtered and dried in an oven. Then the dried carrier was calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0122] (3) Weigh 0.26g chloroplatinic acid, 1.446g ferric nitrate and 9.92g deionized water and prepare them into a nitrate mixture. Then, place the second precursor in it and impregnate it at 30°C for 2h. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2h. Then, place it in a muffle furnace and calcine it at 550°C for 4h to obtain catalyst CAT-11.

[0123] ICP analysis revealed that the catalyst contained 1.01 wt% Pt and 2 wt% Fe.

[0124] Example 12

[0125] (1) 1.5 mL of tetraethyl silicate and 48.5 mL of ethanol were mixed in a round-bottom flask to obtain the first modified solution. 10 g of alumina support was added, and magnetic stirring was turned on. The material in the round-bottom flask was stirred at 30 °C for 4 h. The product was filtered and dried in an oven at 120 °C for 2 h. Then the dried support was calcined in a muffle furnace at 550 °C for 4 h to obtain the first precursor.

[0126] (2) The first precursor was placed in a round-bottom flask containing 10 mL of ethanolamine and 40 mL of ethanol and stirred at 30 °C for 2 h. After that, it was filtered and dried in an oven. Then the dried carrier was calcined in a muffle furnace at 550 °C for 4 h to obtain the second precursor.

[0127] (3) Weigh 0.26g chloroplatinic acid, 1.808g ferric nitrate and 9.92g deionized water and prepare them into a nitrate mixture. Then, place the second precursor in it and impregnate it at 30°C for 2h. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2h. Then, place it in a muffle furnace and calcine it at 550°C for 4h to obtain catalyst CAT-12.

[0128] ICP analysis revealed that the catalyst contained 1.01 wt% Pt and 2.49 wt% Fe.

[0129] Example 13

[0130] The second precursor was obtained by performing steps (1) and (2) according to the method of Example 1.

[0131] (3) Prepare a mixture of 0.26g chloroplatinic acid, 0.285g ammonium molybdate and 9.92g deionized water. Then, place the second precursor in the mixture and impregnate it at 30°C for 2 hours. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2 hours. Then, place it in a muffle furnace and calcine it at 550°C for 4 hours to obtain catalyst CAT-13.

[0132] ICP analysis revealed that the catalyst contained 0.99 wt% Pt and 1.48 wt% Mo.

[0133] Example 14

[0134] The second precursor was obtained by performing steps (1) and (2) according to the method of Example 1.

[0135] (3) Weigh 0.26g chloroplatinic acid, 0.56g sodium hypophosphite and 9.92g deionized water and prepare them into a mixture. Then, place the second precursor in it and impregnate it at 30°C for 2h. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2h. Then, place it in a muffle furnace and calcine it at 550°C for 4h to obtain catalyst CAT-14.

[0136] ICP analysis revealed that the catalyst contained 1.01 wt% Pt and 1.98 wt% P.

[0137] Example 15

[0138] The method is the same as in Example 1, except that the roasting temperature in step (1) is 550°C, the roasting temperature in step (2) is 550°C, and the roasting temperature in step (3) is 650°C.

[0139] The obtained catalyst was designated CAT-15. ICP analysis showed that the catalyst contained 0.40 wt% Pt and 1.49 wt% Fe.

[0140] Comparative Example 1

[0141] Weigh 10g of alumina support and place it in a round-bottom flask. Then weigh 0.26g of chloroplatinic acid, 1.808g of ferric nitrate, and 9.92g of deionized water to prepare a nitrate mixture. The alumina support is then immersed in this mixture and impregnated at 30°C for 2 hours. The impregnated catalyst precursor is then dried in an oven at 120°C for 2 hours, followed by calcination in a muffle furnace at 550°C for 4 hours to obtain catalyst DCAT-1.

[0142] ICP analysis revealed that the catalyst contained 0.99 wt% Pt and 2.49 wt% Fe.

[0143] Comparative Example 2

[0144] The method of Example 12 is followed, except that step (2) is omitted, and the first precursor is directly impregnated in a nitrate mixture. The impregnated catalyst precursor is dried in an oven at 120°C for 2 hours, and then calcined in a muffle furnace at 550°C for 4 hours to obtain catalyst DCAT-2.

[0145] ICP analysis revealed that the catalyst contained 1.02 wt% Pt and 2.51 wt% Fe.

[0146] Comparative Example 3

[0147] (1) Place 10g of alumina support in a round-bottom flask containing 10mL of ethanolamine and 40mL of ethanol and stir at 30℃ for 4h. After that, filter it and dry it in an oven at 120℃ for 2h. Then, place the dried support in a muffle furnace and calcine at 550℃ for 4h.

[0148] (3) Weigh 0.26g chloroplatinic acid, 1.808g ferric nitrate and 9.92g deionized water, prepare them into a nitrate mixture, and then place the product of step (1) into it and impregnate it at 30°C for 2h. After impregnation, place the catalyst precursor in an oven at 120°C and dry it for 2h. Then place it in a muffle furnace and calcine it at 550°C for 4h to obtain catalyst DCAT-3.

[0149] ICP analysis revealed that the catalyst contained 1.01 wt% Pt and 2.5 wt% Fe.

[0150] Comparative Example 4

[0151] Weigh 0.52g of chloroplatinic acid and 9.92g of deionized water to prepare a platinum source mixture. Then, place 10g of alumina support in the mixture and impregnate it at 30℃ for 2h. After impregnation, place the catalyst precursor in an oven at 120℃ and dry it for 2h. Then, place it in a muffle furnace and calcine it at 550℃ for 4h to obtain catalyst DCAT-4.

[0152] ICP analysis showed that the Pt content in the catalyst was 2.01 wt%.

[0153] Comparative Example 5

[0154] Weigh 2.170g of ferric nitrate and 9.92g of deionized water to prepare a nitrate mixture. Then, place 10g of alumina support in the mixture and impregnate it at 30℃ for 2h. After impregnation, place the catalyst precursor in an oven at 120℃ and dry it for 2h. Then, place it in a muffle furnace and calcine it at 550℃ for 4h to obtain catalyst DCAT-5.

[0155] ICP analysis showed that the Fe content in the catalyst was 2.99 wt%.

[0156] Application examples

[0157] The catalysts prepared in the above examples and comparative examples were crushed and sieved to obtain 2g of 20-40 mesh catalyst, which was then loaded into a fixed-bed reactor. Each catalyst was subjected to reduction treatment in the reactor at atmospheric pressure and a pure hydrogen atmosphere at 350°C for 4 hours. After that, the temperature was lowered to the reaction conditions to test the dehydrogenation performance of diphenylamine.

[0158] Under reaction conditions of 295℃ and 0.1 MPa, nitrogen was used as the carrier gas, the molar ratio of nitrogen to diphenylamine was 10:1, the reaction time was 4 h, and the liquid hourly space velocity was 0.36 g·gcat. -1 ·h -1 After the reaction stabilized, the reaction products were condensed and analyzed by offline chromatography. The analytical results are shown in Table 1, where DPA is diphenylamine and CB is carbazole.

[0159] Table 1

[0160] CAT-1 97.78 99.01 CAT-2 97.12 99.35 CAT-3 96.35 98.21 CAT-4 96.10 98.20 CAT-5 92.56 90.56 CAT-6 93.45 93.54 CAT-7 93.71 92.85 CAT-8 90.63 91.98 CAT-9 87.32 82.01 CAT-10 90.12 97.89 CAT-11 95.89 97.23 CAT-12 95.99 97.86 CAT-13 94.35 96.74 CAT-14 93.25 94.32 CAT-15 86.21 82.11 DCAT-1 80.32 75.23 DCAT-2 85.03 81.85 DCAT-3 83.23 90.56 DCAT-4 69.23 45.23 DCAT-5 25.22 38.29

[0161] As can be seen from the results in Table 1, the catalyst prepared by the method provided by the present invention has high catalytic activity with low noble metal loading. When applied to the dehydrogenation reaction of diphenylamine, it has high feed conversion rate and target product selectivity, indicating that the utilization rate of noble metal in the catalyst is significantly improved.

[0162] 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 method for preparing a catalyst, characterized in that, Includes the following steps: (1) The first modified liquid is brought into contact with the alumina carrier for the first modification treatment, and then the first calcination is performed to obtain the first precursor; The first modified liquid comprises a silicon source and a first solvent; the mass ratio of the silicon source to the alumina support, calculated as SiO2, is (0.01-0.07):1; (2) The second modified liquid is brought into contact with the first precursor to perform a second modification treatment, and then a second calcination is performed to obtain the second precursor; The second modified liquid includes an organic amine and a second solvent, and the mass ratio of the second modified liquid to the alumina carrier, based on the mass of the organic amine, is (0.5-2):

1. (3) The active metal component and optional auxiliary component are loaded onto the second precursor, and then a third calcination is performed; The active metal component is Pt, and the auxiliary component is selected from at least one of Fe, Mo and P.

2. The preparation method according to claim 1, wherein, The mass ratio of the silicon source to the alumina support, calculated as SiO2, is (0.03-0.05):

1.

3. The preparation method according to claim 1 or 2, wherein, The temperature of the first modification treatment is 30-100℃, and the time is 1-8h.

4. The preparation method according to claim 3, wherein, The temperature of the first modification treatment is 30-70℃, and the time is 2-6h.

5. The preparation method according to claim 1 or 2, wherein, The conditions for the first roasting include: a temperature of 250-750℃ and a time of 0.5-10h.

6. The preparation method according to claim 5, wherein, The conditions for the first roasting include: a temperature of 450-650℃ and a time of 3-6 hours.

7. The preparation method according to claim 1 or 2, wherein, The volume ratio of silicon source to first solvent is 1:(10-200).

8. The preparation method according to claim 7, wherein, The volume ratio of silicon source to first solvent is 1:(15-120).

9. The preparation method according to claim 1 or 2, wherein, The silicon source is selected from at least one of tetraethyl silicate, methyltriethoxysilane, trimethylchlorosilane, propyltriethoxysilane, tetrachlorosilane, and aminosilane.

10. The preparation method according to claim 1 or 2, wherein, The first solvent is selected from C1-C6 fatty alcohols.

11. The preparation method according to claim 10, wherein, The first solvent is selected from at least one of methanol, ethanol, propanol, butanol, glycerol and isopropanol.

12. The preparation method according to claim 1 or 2, wherein, The mass ratio of the second modified liquid to the alumina carrier, based on the mass of organic amine, is (0.8-1.2):

1.

13. The preparation method according to claim 1 or 2, wherein, The volume ratio of organic amine to the second solvent is 1:(1-10).

14. The preparation method according to claim 1 or 2, wherein, The second modification treatment is carried out at a temperature of 30-100℃ for 1-8 hours.

15. The preparation method according to claim 14, wherein, The second modification treatment is carried out at a temperature of 30-70℃ for 2-6 hours.

16. The preparation method according to claim 1 or 2, wherein, The conditions for the second calcination include: a temperature of 250-750℃ and a time of 0.5-10h.

17. The preparation method according to claim 16, wherein, The conditions for the second roasting include: a temperature of 450-650℃ and a time of 3-6 hours.

18. The preparation method according to claim 1 or 2, wherein, The organic amine is selected from at least one of n-propanolamine, ethanolamine, triethanolamine, diethanolamine, isopropanolamine, isobutanolamine, and n-butanolamine.

19. The preparation method according to claim 1 or 2, wherein, The second solvent is selected from C1-C6 fatty alcohols.

20. The preparation method according to claim 1 or 2, wherein, The mass ratio of the active metal component to the auxiliary component is 1:(0.1-10) based on elemental composition.

21. The preparation method according to claim 20, wherein, The mass ratio of the active metal component to the auxiliary component is 1:(1.5-6) ​​based on elemental composition.

22. The preparation method according to claim 1 or 2, wherein, The method of loading the active metal component and optional auxiliary component onto the second precursor in step (3) includes: impregnating the second precursor with an impregnation solution containing the active metal component precursor and optional auxiliary component precursor.

23. The preparation method according to claim 22, wherein, The concentration of the impregnation solution is 0.01-0.2 mol / L.

24. The preparation method according to claim 23, wherein, The concentration of the impregnation solution is 0.02-0.1 mol / L.

25. The preparation method according to claim 1 or 2, wherein, The conditions for the third roasting include: a temperature of 250-750℃ and a time of 0.5-10h.

26. The preparation method according to claim 25, wherein, The conditions for the third roasting include: a temperature of 450-650℃ and a time of 3-6 hours.

27. The preparation method according to claim 1 or 2, wherein, The preparation method further includes: reducing the product obtained by the third calcination under hydrogen conditions.

28. The preparation method according to claim 27, wherein, The conditions for the reduction treatment include: a temperature of 200-600℃, a hydrogen pressure of 0-0.1MPa, and a time of 1-10h.

29. The catalyst prepared by any one of claims 1-28.

30. The catalyst according to claim 29, wherein, Based on the total amount of the catalyst, the content of the active metal component is 0.1-5 wt% and the content of the auxiliary component is 0.1-10 wt% (elemental basis).

31. A method for synthesizing nitrogen-containing heterocyclic compounds by dehydrogenation of diphenylamine, characterized in that, The method includes: contacting diphenylamine with a dehydrogenation catalyst under dehydrogenation reaction conditions; The dehydrogenation catalyst is the catalyst described in claim 29 or 30.

32. The method according to claim 31, wherein, The conditions for the dehydrogenation reaction include: a temperature of 250-400℃, a pressure of 0-0.1 MPa, and a liquid hourly space velocity of 0.1-0.5 g·gcat. -1 ·h -1 .

33. The method according to claim 31 or 32, wherein, The contact is carried out in the presence of a carrier gas, namely nitrogen, with a molar ratio of nitrogen to diphenylamine of (1-50):

1.

34. The method according to claim 31 or 32, wherein, No organic solvents need to be introduced during the contact process.