Method for synthesizing aniline

Abstract

The present application provides a new method for synthesizing aniline, which uses alcohol compounds as raw materials and liquid ammonia as a nitrogen source. Cyclohexanol and its various derivatives are efficiently converted into aniline and corresponding aromatic amines over a Pt-based catalyst without an external hydrogen source. Compared with traditional methods for synthesizing aniline, cyclohexanol as a raw material has the advantages of being inexpensive, readily available, and can be obtained from renewable biomass energy, avoiding the limitation of traditional methods that rely on increasingly depleted fossil resources such as benzene, toluene, and xylene as raw materials. Secondly, the entire reaction pathway produces water as the main by-product and does not require the participation of auxiliary agents, avoiding the production of environmentally harmful substances and having the advantage of being more environmentally friendly. At the same time, the reaction itself is carried out without an external hydrogen source, and the reuse of hydrogen in cyclohexanol enables this synthesis method to have higher atomic utilization and atom economy. The resulting product, aniline, as the most important class of amine compounds, has extremely high added value.

Description

Technical Field

[0001] The present application relates to the field of industrial synthesis technology, and in particular to a method for synthesizing aniline. Background Art

[0002] As one of the most important amine compounds, aniline is widely used in the production of medicines, dyes, agricultural chemicals and various polymers, and has extremely high added value.

[0003] Traditional aniline synthesis methods primarily use aromatic hydrocarbons as raw materials, undergoing halogenation and nitration to produce halogenated aromatics and nitro compounds, followed by further coupling or hydrogenation. With the increasing depletion of fossil fuels, the application of aromatic hydrocarbons such as benzene and toluene has been significantly limited. Halogenation and nitration processes often produce toxic and hazardous substances. Furthermore, the large amount of additives used in the coupling reaction significantly limits its practical application. Furthermore, in the phenol-based aniline synthesis method, the consumption of an external hydrogen source and alkali metal additives significantly increases production costs.

[0004] Therefore, a green, environmentally friendly, low-cost, sustainable and efficient aniline synthesis method is urgently needed. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a method for synthesizing aniline.

[0006] Based on the above-mentioned purpose, the present application provides a method for synthesizing aniline, comprising: reacting a cyclohexanol compound and liquid ammonia in an organic reaction medium at 160-250°C under the action of a Pt-based catalyst to obtain aniline; wherein the Pt-based catalyst comprises a carrier and Pt supported on the carrier, and the carrier is selected from at least one of metal oxides, SiO2 and activated carbon; and the particle size of the Pt is 1-20 nm.

[0007] As can be seen from the above, a novel and efficient aniline synthesis method provided by the application, under the premise of taking alcohol compounds as substrate, taking liquid ammonia as nitrogen source, realizing efficient conversion of alcohol to aniline in organic phase on Pt-based catalyst under the condition of no external hydrogen source, the aniline product obtained with higher yield is widely used in the production of medicine, dye, agricultural chemicals and various polymers, and has very high added value. Compared to traditional synthesis methods, this method is raw material with cyclohexanol and its derivatives, has the advantage of being cheap and easy to obtain, and biomass energy can be used as the source of cyclohexanol and its derivatives, making the source of raw materials more extensive and more sustainable. Recycling of hydrogen in cyclohexanol makes the reaction itself can be carried out under hydrogen-free conditions, thereby making it have higher atom utilization and atom economy. Meanwhile, compared to phenol amination synthesis of aniline, this synthesis method is catalytically active component with a simple, efficient and stable platinum-based catalyst, does not need alkali metal auxiliary agents, avoids the large-scale use of precious metal palladium and alkali metal auxiliary agents, thereby greatly saving production costs, making it have certain application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in this application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are merely embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0009] Figure 1 Schematic diagram of the aniline synthesis method according to an embodiment of the present application;

[0010] Figure 2 is an XRD spectrum of an exemplary Pt-based catalyst according to an embodiment of the present application;

[0011] Figure 3 This is a STEM image of an exemplary Pt-based catalyst according to an embodiment of the present application. DETAILED DESCRIPTION

[0012] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0013] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meanings understood by persons having ordinary skills in the field to which this application belongs. The words "include" or "comprise" and the like used in the embodiments of this application mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, but do not exclude other elements or objects.

[0014] Aniline, one of the most important amine compounds, is widely used in the production of pharmaceuticals, dyes, agricultural chemicals, and various polymers, possessing high added value. Traditional aniline synthesis methods primarily utilize aromatic hydrocarbons as raw materials, undergoing halogenation and nitration to produce halogenated aromatic hydrocarbons and nitro compounds, which are then further synthesized by coupling or hydrogenation. The increasing depletion of fossil fuels has significantly limited the application of aromatic hydrocarbons such as benzene and toluene. Halogenation and nitration processes are often accompanied by the production of toxic and hazardous substances. Furthermore, the use of large amounts of additives in coupling reactions significantly restricts their practical application.

[0015] As a preferred method for synthesizing aniline, phenol amination has promising applications. Compared to fossil fuel-based raw materials such as benzene and toluene, phenol is cheaper, more readily available, and more widely available. It can also be obtained from renewable biomass energy, making it more sustainable. Furthermore, the amination of phenol to aniline primarily produces water as a byproduct, making it more environmentally friendly. However, the types of catalysts for the amination of phenol to aniline are very limited, primarily to precious metal palladium-based catalysts, and the amount of palladium required is very large, significantly increasing production costs. Furthermore, the large consumption of external hydrogen sources, the use of alkali metal additives, and the poor selectivity for aniline remain the main challenges facing phenol amination at this stage. Therefore, there is an urgent need to develop efficient, inexpensive catalytic systems and environmentally friendly synthesis methods to achieve the efficient preparation of aromatic amines such as aniline.

[0016] To solve the above problems, the present invention provides a novel and efficient method for synthesizing aniline. Figure 1 As shown, aniline is obtained through a series of reactions in an organic phase over a Pt-based catalyst using cyclohexanols, a relatively inexpensive and readily available raw material, as raw materials and liquid ammonia as a nitrogen source, without the need for an external hydrogen source. The molar ratio of cyclohexanols to Pt is only 1:(0.002-0.01). Optimization of the support and preparation method enhances the activity of the catalyst in cyclohexanol dehydrogenation, thereby accelerating substrate conversion. Furthermore, through support screening, research, and optimization, the effect of benzene on the aniline product is explored, minimizing the side reaction from cyclohexanol to benzene. Ultimately, the efficient conversion of cyclohexanol to aniline is achieved with a high yield of aniline. This efficient conversion of cyclohexanols to aniline can, to a certain extent, address the high cost and environmental hazards of current aniline preparation methods.

[0017] The method for synthesizing aniline according to an embodiment of the present application may include reacting a cyclohexanol compound and liquid ammonia in an organic reaction medium at 160-250°C in the presence of a Pt-based catalyst to produce aniline. The Pt-based catalyst includes a support and Pt supported on the support, wherein the support is selected from at least one of a metal oxide, SiO2, and activated carbon. The Pt particles may have a size of 1-20 nm.

[0018] Figure 2-Figure 3 : shows the relevant parameter information of the exemplary Pt-based catalyst of the embodiment of the present application. Figure 2 1 is an XRD spectrum of an exemplary Pt-based catalyst according to an embodiment of the present application. Figure 3 : is an STEM image of an exemplary Pt-based catalyst according to an embodiment of the present application. Figure 3 The catalysts for parts a, b and c are Pt / CeO2; the catalysts for parts d, e and f are Pt / γ-Al2O3; and the catalysts for parts g, h and i are Pt / C.

[0019] Depend on Figure 2 It can be seen that the Pt-based catalyst used in the examples of this application, the phase structure information of the platinum-based catalyst obtained by XRD spectrum shows that the diffraction peaks are all attributed to the diffraction peaks of the corresponding carrier, and no obvious platinum diffraction peaks are seen, indicating that the Pt-based catalyst used in the examples of this application has a low platinum loading and high dispersion. Figure 3 It can be seen that the presence characteristics of Pt in the platinum-based catalyst obtained through the image show that Pt exists in the form of particles with a particle size between 1-20nm and is evenly dispersed.

[0020] The principle of the method for synthesizing aniline provided in the embodiments of the present application is that cyclohexanol compounds are dehydrogenated to obtain cyclohexanone compounds, the cyclohexanone compounds are subjected to amination and addition of hydrogen removed by cyclohexanol to obtain cyclohexylamine, and the cyclohexylamine is further dehydrogenated to obtain aniline. Among them, the Pt-based catalyst has extremely strong selectivity for the dehydrogenation sites of cyclohexanol compounds. For the process of dehydrogenating cyclohexanol compounds to obtain cyclohexanone compounds, the activity of cyclohexanol dehydrogenation can be improved by the active component Pt at the metal-support interface in the Pt-based catalyst, and the selectivity of cyclohexanol dehydrogenation can be improved by the support, thereby suppressing the side reaction of dehydrating cyclohexanol compounds to obtain benzene to a certain extent, thereby improving the conversion rate of obtaining cyclohexanone compounds, and then being able to obtain aniline with a higher yield, achieving efficient conversion of cyclohexanone to aniline.

[0021] The aniline synthesis method of the embodiment of the present application mainly uses cyclohexanol compounds as raw materials and liquid ammonia as nitrogen source. Under the condition of no external hydrogen source, cyclohexanol and its various derivatives are efficiently converted into aniline and corresponding aromatic amines on a Pt-based catalyst. Compared with the traditional method of synthesizing aniline, cyclohexanol as raw material has the advantages of being cheap and easy to obtain, and can be obtained from renewable biomass energy, avoiding the limitation of traditional methods using increasingly depleted fossil resources such as benzene, toluene, and xylene as raw material sources; secondly, the entire reaction path uses water as the main by-product and does not require the participation of auxiliary agents, avoiding the production of environmentally harmful substances and having the advantage of being more green and environmentally friendly; at the same time, the reaction itself is carried out under the condition of no external hydrogen source, and the reuse of hydrogen in cyclohexanol makes the synthesis method have higher atomic utilization and atomic economy. The resulting product aniline, as the most important class of amine compounds, is widely used in the production of medicines, dyes, agricultural chemicals and various polymers, and has extremely high added value.

[0022] The cyclohexanol compounds mainly refer to fatty alcohols with cyclohexanol as the basic unit, including cyclohexanol, methylcyclohexanol, ethylcyclohexanol, propylcyclohexanol, chlorocyclohexanol, bromocyclohexanol, tert-butylcyclohexanol, etc., without specific limitation.

[0023] In some possible embodiments, the cyclohexanol compound is mainly a fatty alcohol with cyclohexanol as the basic structural unit. The alcohol fat with cyclohexanol as the basic structural unit mainly refers to that the hydroxyl group is directly connected to the saturated six-membered carbon ring. For other fatty alcohols with substituents with cyclohexanol as the basic unit, the type and position of the substituent are not clearly defined. For example, the type of substituent can include methyl, ethyl, propyl, tert-butyl, chloro, bromo, etc., which are specifically not limited. For example, the position of the substituent can include ortho, meta, para, etc., which are specifically not limited. Preferably, the cyclohexanol compound can include at least one of cyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, 2-ethylcyclohexanol, 4-ethylcyclohexanol, 2-propylcyclohexanol, 2-chlorocyclohexanol, 2-bromocyclohexanol and 4-tert-butylcyclohexanol.

[0024] The Pt-based catalyst can be a supported platinum-based catalyst, specifically a metal oxide-supported platinum-based catalyst, an activated carbon-supported platinum-based catalyst, a silicon oxide (SiO2)-supported platinum-based catalyst, a nickel aluminum spinel-supported platinum-based catalyst, and a hydroxyapatite-supported platinum-based catalyst, etc., without specific limitation. It can be understood that the Pt-based catalyst can include a carrier and Pt supported on the carrier. Wherein, the carrier can be selected from at least one of metal oxide, hydroxyapatite, SiO2 and activated carbon.

[0025] In some embodiments, the metal oxide may be selected from at least one of Group IIIA metal oxides, Group IIA metal oxides, Group IVB metal oxides, and lanthanide metal oxides, for example, at least one of spinel NiAl2O4, Al2O3, ZrO2, and CeO2.

[0026] The organic reaction medium may include toluene, m-xylene, p-xylene, mesitylene, ethylene glycol dimethyl ether and cyclopentyl methyl ether, etc., without specific limitation. In some embodiments, the organic reaction medium includes at least one of toluene and p-xylene.

[0027] In some possible embodiments, the pressure of the liquid ammonia after gasification may be 0.1-1 MPa, preferably 0.4-0.6 MPa, and is not specifically limited thereto, for example, it may be 0.4 MPa, 0.5 MPa or 0.6 MPa.

[0028] In some possible embodiments, the molar ratio of the reaction substrate cyclohexanol compound to the platinum in the Pt-based catalyst used is 1:(0.002-0.01), preferably 1:(0.004-0.008), and is not specifically limited, for example, it can be 1:0.004, 1:0.006, or 1:0.008.

[0029] In some possible embodiments, the mass ratio of the reaction substrate cyclohexanol compound to the reaction phase organic reaction medium can be 1:(1-50), preferably 1:(1-40), and is not specifically limited, for example, it can be 1:10, 1:25, or 1:30.

[0030] In some possible embodiments, the reaction temperature is 160-250°C, preferably 180-200°C.

[0031] The reaction temperature described in this application refers to the temperature required for the conversion of cyclohexanol compounds to aniline, which can be 160-250°C, preferably 180-200°C, for example, 180°C, 190°C, or 200°C, without specific limitation. The platinum-based catalyst described in this application has high activity in converting cyclohexanol to aniline. Compared to other methods, the reaction temperature can be lower than 200°C, allowing efficient conversion of cyclohexanol to aniline under relatively mild conditions, saving energy consumption.

[0032] In some possible embodiments, the reaction time is 1-24 h, preferably 10-16 h.

[0033] The reaction time described in this application refers to the time required for the conversion of cyclohexanol compounds into aniline, which can be 1-24 hours, preferably 10-16 hours, and is not specifically limited, for example, it can be 10 hours, 12 hours, or 15 hours.

[0034] In some possible embodiments, batch and flow reaction processes can be used to synthesize aniline. The reactor used in the batch reaction process is a batch reactor, and the flow reaction process is a fixed bed.

[0035] The process provided in the present application for preparing aniline in a batch reactor using cyclohexanol compounds as reaction substrates can include: preparing a prescribed amount of cyclohexanol compounds, a platinum-based catalyst, and an organic reaction medium, adding the cyclohexanol compounds, the platinum-based catalyst, and the reaction phase to a batch reactor, and reacting for 10-16 hours under conditions of an ammonia partial pressure of 0.4-0.6 MPa and a reaction temperature of 180-200°C.

[0036] The present application also provides a method for determining the conversion rate and yield of aniline synthesis. The determination method can be as follows: the reaction product is subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A), using an HP-5 chromatographic column, and the temperature program conditions of the chromatographic column are: 50°C for 10 minutes, and 10°C / min for 10 minutes. -1 The temperature was raised to 250 °C and maintained at 250 °C for 5 min.

[0037] Pt-based catalysts can be prepared using methods such as isovolumetric impregnation, excess impregnation, and precipitation deposition. Metal oxide supports can be prepared using high-temperature thermal decomposition, precipitation, hydrothermal, and solvothermal methods. The support is selected from cerium oxide, which is prepared by thermally decomposing cerium nitrate hexahydrate at a temperature of 400°C to 600°C.

[0038] In some embodiments, the Pt-based catalyst can be prepared by isovolumetric impregnation, that is, a platinum precursor is impregnated onto a corresponding support, dried, calcined, and then reduced at high temperature to obtain the corresponding platinum-based catalyst. Specifically, the preparation method of the Pt-based catalyst includes:

[0039] Providing the carrier; the water absorption rate of the carrier is 50% to 765%;

[0040] Providing a precursor solution; the concentration of the precursor solution is 0.022 g / ml to 0.050 g / ml, and the volume is 298 μL to 682 μL;

[0041] pouring the support into the precursor solution, drying and calcining;

[0042] The calcined product is reduced in a reducing gas.

[0043] The precursor of platinum in the Pt-based catalyst may include an aqueous solution of platinum or an alcoholic solution of platinum. The aqueous solution of platinum may include at least one of an aqueous solution of platinum nitrate and an aqueous solution of chloroplatinic acid. The alcoholic solution of platinum includes at least one of a methanol solution of platinum nitrate, a methanol solution of chloroplatinic acid, and a n-butanol solution of platinum nitrate. In some embodiments, the precursor of platinum may include at least one of an aqueous solution of platinum nitrate, a methanol solution of platinum nitrate, an aqueous solution of chloroplatinic acid, a methanol solution of chloroplatinic acid, and a n-butanol solution of platinum nitrate. The metal oxide type support may be prepared by a high-temperature thermal decomposition method.

[0044] The concentration of the precursor solution can be adjusted based on the saturated water absorption of different carriers. The corresponding platinum precursor solution can be prepared into a solution of corresponding concentration. The Pt loading in the Pt-based catalyst is 1.5 wt %. Based on this loading, the corresponding volume of precursor solution with the corresponding concentration can be prepared.

[0045] After the support is poured into the precursor solution, it can be stirred continuously and then ultrasonicated for 10-20 minutes to ensure uniform dispersion of the Pt in the support. Drying can be done by drying in an oven at 100°C overnight. Calcination can be done by grinding the dried product and then calcining it at high temperature in a muffle furnace.

[0046] The calcination temperature can be 300°C-550°C, preferably 400°C-500°C. More preferably, it is 450°C-500°C, for example, 450°C, 480°C, or 500°C, with no specific limitation, and preferably at least one of 450°C and 500°C. The calcination time is 3-12 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, or 10 hours, with no specific limitation, and preferably 5 hours-10 hours, for example, at least one of 5 hours, 8 hours, or 10 hours. More preferably, it is 5 hours-8 hours.

[0047] The volume fraction of hydrogen in the reducing gas may be 5%-30%, preferably 10%-20%.

[0048] In the present application, reducing gas refers to the gas used to reduce the platinum-based catalyst. The reducing gas can be a mixed gas of hydrogen and argon. The volume fraction of hydrogen refers to the volume percentage of hydrogen in the mixed gas. The volume percentage can be 5-30%, preferably 10-20%. For example, it can be 10%, 15%, 20%, etc., and there is no specific limitation.

[0049] In some embodiments, the flow rate of the reducing gas may be 10-150 ml / min. -1 , preferably 20-80 ml / min -1 ; For example, it can be 20ml / min -1 、30ml / min -1、40ml / min -1 、60ml / min -1 、80ml / min -1 More preferably, the flow rate of the reducing gas is 30 ml / min to 80 ml / min.

[0050] Preferably, the reduction temperature may be 200-500°C, preferably 300-400°C, more preferably 350-400°C.

[0051] In the present application, the reduction temperature refers to the temperature when the platinum-based catalyst is reduced by a reducing gas. The temperature can be 200-400°C, preferably 300°C to 400°C, and more preferably 350-400°C. For example, it can be 350°C, 370°C, 390°C or 400°C, etc., and is not specifically limited.

[0052] Preferably, the reduction time may be 1-5 hours, preferably 3-4 hours.

[0053] In the present application, the reduction time refers to the time for reducing the platinum-based catalyst, which may be 1-5 hours, preferably 3-4 hours, for example, 3 hours, 3.5 hours, 4 hours, etc., and is not specifically limited.

[0054] The examples of the present application improve the activity of the Pt-based catalyst in the dehydrogenation of cyclohexanol by optimizing the above-mentioned carrier and preparation method, thereby accelerating the conversion of the substrate cyclohexanol compounds; at the same time, through the screening of the carrier, the side reaction of cyclohexanol to benzene is minimized as much as possible, and ultimately, the efficient conversion of cyclohexanol to aniline is achieved with a higher yield of aniline.

[0055] The novel aniline synthesis method provided in the embodiments of the present application can achieve efficient conversion of cyclohexanol to aniline over a Pt-based catalyst in the absence of hydrogen. The aniline product obtained in high yield is widely used in the production of dyes, agricultural chemicals, pharmaceuticals, and various polymers. Using cheap and readily available cyclohexanol as a substrate greatly reduces the cost of aniline synthesis. Reusing hydrogen from the alcohol substrate allows the reaction to proceed in the absence of hydrogen, significantly improving the atomic utilization and atom economy of the reaction. Furthermore, the absence of added additives and the fact that the reaction itself produces water as a major byproduct make it more environmentally friendly. Furthermore, this synthesis method is universally applicable to various substituted cyclohexanols, such as methylcyclohexanol, ethylcyclohexanol, propylcyclohexanol, and chlorocyclohexanol.

[0056] The technical solution of this application is further explained below with reference to specific implementation methods.

[0057] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0058] Unless otherwise specified, the test materials used in the following examples were purchased from conventional biochemical reagent stores.

[0059] Example 1 Screening of platinum precursors for Pt-based catalysts

[0060] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0061] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0062] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0063] The measurement results are shown in Table 1.

[0064] Example 2 Screening of carriers for platinum precursors of Pt-based catalysts

[0065] The difference between Example 2 and Example 1 is that the platinum precursor is a methanol solution of platinum nitrate, the concentration of platinum in the methanol solution of platinum nitrate is 0.030 g / ml, and the amount of the solution used is 501 μl.

[0066] Example 3 Screening of platinum precursors for Pt-based catalysts

[0067] The difference between Example 3 and Example 1 is that the platinum precursor is a platinum nitrate n-butanol solution. The concentration of platinum in the platinum nitrate n-butanol solution is 0.032 g / ml, and the amount of solution used is 469 μl.

[0068] Example 4 Screening of platinum precursors for Pt-based catalysts

[0069] The difference between Example 4 and Example 1 is that the platinum precursor is a chloroplatinic acid aqueous solution. The concentration of platinum in the chloroplatinic acid aqueous solution is 0.031 g / ml, and the amount of solution used is 484 μl.

[0070] Example 5 Screening of platinum precursors for Pt-based catalysts

[0071] The difference between Example 5 and Example 1 is that the platinum precursor is a methanol solution of chloroplatinic acid, the concentration of platinum in the methanol solution of chloroplatinic acid is 0.030 g / ml, and the amount of the solution used is 501 μl.

[0072] Table 1 Conversion rate of reaction substrate and molar yield of product in Examples 1-5

[0073]

[0074] Result analysis: As shown in Table 1, the catalysts prepared with different platinum precursors all have catalytic activity in the reaction of cyclohexanol to aniline. Among them, the catalytic activity is good when platinum nitrate is used as the precursor, and the catalytic activity is the best when the aqueous solution of platinum nitrate is used as the precursor.

[0075] Example 6 Screening of Metal Oxide Supports for Pt-Based Catalysts

[0076] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0077] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0078] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0079] The measurement results are shown in Table 2.

[0080] Example 7 Screening of Metal Oxide Supports for Pt-Based Catalysts

[0081] The only difference between Example 7 and Example 6 is that the carrier in Example 7 is aluminum oxide. The concentration of platinum in the platinum nitrate aqueous solution is 0.024 g / ml, and the amount of solution used is 634 μl.

[0082] Example 8 Screening of carriers for Pt-based catalysts

[0083] The only difference between Example 8 and Example 6 is that the carrier in Example 8 is activated carbon. The concentration of platinum in the platinum nitrate aqueous solution is 0.050 g / ml, and the amount of solution used is 298 μl.

[0084] Example 9 Screening of carriers for Pt-based catalysts

[0085] The only difference between Example 9 and Example 6 is that the carrier in Example 7 is nickel aluminum spinel. The concentration of platinum in the platinum nitrate aqueous solution is 0.022 g / ml, and the amount of solution used is 682 μl.

[0086] Example 10 Screening of carriers for Pt-based catalysts

[0087] The only difference between Example 10 and Example 6 is that the carrier in Example 7 is silicon oxide. The concentration of platinum in the platinum nitrate aqueous solution is 0.037 g / ml, and the amount of solution used is 406 μl.

[0088] Table 2 Conversion rate of reaction substrate and molar yield of product in Examples 6-10

[0089]

[0090] Results Analysis: The results in Table 2 demonstrate that the platinum-based catalysts prepared using the selected metal oxides as supports are capable of producing aniline in the cyclohexanol-to-aniline reaction. Alumina and cerium oxide, in particular, facilitate uniform distribution of platinum and exhibit excellent stability, enabling a more stable interaction between platinum and the metal in the support. This effectively inhibits the dehydration of cyclohexanol, thereby suppressing the side reaction of cyclohexanol to benzene, and promotes the dehydrogenation of cyclohexanol, thereby accelerating the conversion of cyclohexanol to cyclohexanone, ultimately resulting in a relatively good aniline yield.

[0091] Example 11 Screening of Calcination Temperature and Calcination Time for Preparation of Pt-Based Catalysts

[0092] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes, dry in an oven at 100°C overnight, grind and crush, and calcine at high temperature in a muffle furnace, specifically calcine at 200°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0093] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0094] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0095] The measurement results are shown in Table 3.

[0096] Example 12 Screening of Calcination Temperature and Calcination Time for Preparation of Pt-Based Catalysts

[0097] The only difference between Example 12 and Example 11 is that the calcination temperature in Example 12 is 300°C.

[0098] Example 13 Screening of Calcination Temperature and Calcination Time for Preparation of Pt-Based Catalysts

[0099] The only difference between Example 13 and Example 11 is that the calcination temperature in Example 13 is 300°C.

[0100] Example 14 Screening of Calcination Temperature and Calcination Time for Preparation of Pt-Based Catalysts

[0101] The only difference between Example 14 and Example 11 is that the calcination temperature in Example 14 is 300°C.

[0102] Example 15 Screening of Calcination Temperature and Calcination Time for Preparation of Pt-Based Catalysts

[0103] The only difference between Example 15 and Example 11 is that the calcination temperature in Example 15 is 300°C.

[0104] Example 16 Screening of Calcination Temperature and Calcination Time for Preparation of Pt-Based Catalysts

[0105] The only difference between Example 16 and Example 11 is that the roasting temperature in Example 16 is 300° C. and the roasting time is 8 hours.

[0106] Example 17 Screening of Calcination Temperature and Calcination Time for Preparation of Pt-Based Catalysts

[0107] The only difference between Example 17 and Example 11 is that the roasting temperature in Example 17 is 300° C. and the roasting time is 10 h.

[0108] Table 3 Conversion rate of reaction substrate and molar yield of product in Examples 11-17

[0109]

[0110]

[0111] The results in Table 3 demonstrate that the calcination temperature during catalyst preparation significantly affects catalyst performance. Both excessively low and high calcination temperatures are detrimental to substrate conversion and product formation. A calcination temperature of 400°C to 500°C favors the production of platinum particles with a particle size distribution within the 1-20 nm range, resulting in excellent catalyst activity and, in turn, improved molar yields of cyclohexanols and aniline.

[0112] Example 18 Screening of the Volume Fraction of Hydrogen in the Reducing Gas, the Reducing Gas Flow Rate, and the Reduction Time for the Preparation of Pt-Based Catalysts

[0113] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes, dry in an oven at 100°C overnight, grind and crush, and calcine at high temperature in a muffle furnace, specifically calcine at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 5%, and the reducing gas flow rate is 30ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0114] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0115] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0116] The measurement results are shown in Table 4.

[0117] Example 19 Screening of the Volume Fraction of Hydrogen in the Reducing Gas, the Reducing Gas Flow Rate, and the Reduction Time for the Preparation of Pt-Based Catalysts

[0118] The only difference between Example 19 and Example 18 is that the volume fraction of hydrogen in the reducing gas in Example 19 is 10%.

[0119] Example 20 Screening of the Volume Fraction of Hydrogen in the Reducing Gas, the Reducing Gas Flow Rate, and the Reduction Time during the Preparation of Pt-Based Catalysts

[0120] The only difference between Example 20 and Example 18 is that the volume fraction of hydrogen in the reducing gas in Example 20 is 15%.

[0121] Example 21 Screening of the Volume Fraction of Hydrogen in the Reducing Gas, the Reducing Gas Flow Rate, and the Reduction Time for the Preparation of Pt-Based Catalysts

[0122] The only difference between Example 21 and Example 18 is that the volume fraction of hydrogen in the reducing gas in Example 21 is 10%, and the gas flow rate is 60 ml / min. -1 .

[0123] Example 22 Screening of the Volume Fraction of Hydrogen in the Reducing Gas, the Reducing Gas Flow Rate, and the Reduction Time for the Preparation of Pt-Based Catalysts

[0124] The only difference between Example 22 and Example 18 is that the volume fraction of hydrogen in the reducing gas in Example 22 is 10%, and the gas flow rate is 80 ml / min. -1 .

[0125] Example 23 Screening of the Volume Fraction of Hydrogen in the Reducing Gas, the Reducing Gas Flow Rate, and the Reduction Time for the Preparation of Pt-Based Catalysts

[0126] The only difference between Example 23 and Example 18 is that the volume fraction of hydrogen in the reducing gas in Example 23 is 10%, and the gas flow rate is 60 ml / min. -1 , the restoration time is 2 hours.

[0127] Example 24 Screening of the Volume Fraction of Hydrogen in the Reducing Gas, the Reducing Gas Flow Rate, and the Reduction Time for the Preparation of Pt-Based Catalysts

[0128] The only difference between Example 24 and Example 18 is that the volume fraction of hydrogen in the reducing gas in Example 24 is 10%, and the gas flow rate is 60 ml / min. -1 , the restoration time is 6 hours.

[0129] Table 4 Conversion rate of reaction substrate and molar yield of product in Examples 18-24

[0130]

[0131] The results in Table 4 demonstrate that the reduction conditions during catalyst preparation significantly influence its performance. The hydrogen volume fraction in the reducing gas and the reduction duration, in particular, significantly influence product formation. A catalyst with a hydrogen volume fraction of 10% to 15%, a reducing gas flow rate of 30 to 80 ml / min, and a reduction duration of 2 to 4 hours exhibits excellent performance, producing a relatively high yield of aniline.

[0132] Example 25 Screening of reduction temperature during preparation of Pt-based catalysts

[0133] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 200 °C.

[0134] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0135] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0136] The measurement results are shown in Table 5.

[0137] Example 26 Screening of reduction temperature during preparation of Pt-based catalysts

[0138] The only difference between Example 26 and Example 25 is that the reduction temperature of Example 26 is 300°C.

[0139] Example 27 Screening of reduction temperature during preparation of Pt-based catalysts

[0140] The only difference between Example 27 and Example 25 is that the reduction temperature of Example 26 is 400°C.

[0141] Example 28 Screening of reduction temperature during preparation of Pt-based catalysts

[0142] The only difference between Example 28 and Example 25 is that the reduction temperature of Example 26 is 500°C.

[0143] Table 5 Conversion rate of reaction substrate and molar yield of product in Examples 25-28

[0144]

[0145] The results in Table 5 demonstrate that the reduction temperature significantly affects the formation of aniline; both excessively low and high reduction temperatures are detrimental to aniline production. A reduction temperature of 300-400°C balances the metallicity and oxidation state of the active component, palladium, in the catalyst, resulting in excellent catalytic dehydrogenation activity. This effectively inhibits the dehydration of cyclohexanol, which in turn inhibits the side reaction from cyclohexanol to benzene, promotes the dehydrogenation of cyclohexanol, and thus the conversion of cyclohexanol to cyclohexanone, ultimately resulting in a relatively good aniline yield.

[0146] Example 29 Screening of Preparation Methods for Pt-Based Catalyst Supports

[0147] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0148] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0149] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0150] The measurement results are shown in Table 6.

[0151] Example 30 Screening of Preparation Methods for Pt-Based Catalyst Supports

[0152] The only difference between Example 30 and Example 29 is that in Example 30, cubic cerium oxide is prepared by a hydrothermal method. The specific preparation method of the hydrothermal method can be as follows: 19 grams of flaky sodium hydroxide is dissolved in 70 ml of ultrapure water for later use, 1.732 g of cerium nitrate hexahydrate is dissolved in 10 ml of ultrapure water, and the cerium nitrate solution is added dropwise to the sodium hydroxide solution with continuous stirring. After the addition is complete, stirring is continued at room temperature for 30 minutes, and then the liquid is poured into the lining of the crystallization reactor, sealed, and hydrothermaled at 180°C for 24 hours. After the hydrothermal reaction is completed, the obtained solid is separated by suction, washed with ultrapure water to a pH of 7, and the filter cake is dried in a 100°C oven for 12 hours, followed by calcination in a muffle furnace at 500°C for 3 hours to obtain rod-shaped cerium oxide.

[0153] Example 31 Screening of Preparation Methods for Pt-Based Catalyst Supports

[0154] The only difference between Example 31 and Example 30 is that in Example 31, when cerium oxide with a rod-like morphology is prepared by a hydrothermal method, the hydrothermal reaction conditions are hydrothermal treatment at 180° C. for 24 hours.

[0155] Example 32 Screening of Preparation Methods for Pt-Based Catalyst Supports

[0156] The only difference between Example 32 and Example 29 is that in Example 32, octahedral cerium oxide is prepared by a hydrothermal method. The specific preparation method of the hydrothermal method can be: 0.008 grams of sodium phosphate dodecahydrate is dissolved in 70 ml of ultrapure water for standby use, and 0.858 g of cerium nitrate hexahydrate is dissolved in 10 ml of ultrapure water. The aqueous solution of cerium nitrate is added dropwise to the sodium phosphate solution, and the process is continuously stirred. After the addition is completed, stirring is continued at room temperature for 30 minutes, and then the liquid is poured into the lining of the crystallization reactor, sealed, and hydroheated at 170°C for 24 hours. After the hydrothermal reaction is completed, the obtained solid is separated by suction filtration, washed with ultrapure water to pH = 7, and the filter cake is dried in a 100°C oven for 12 hours, and then calcined in a muffle furnace at 500°C for 3 hours to obtain octahedral cerium oxide.

[0157] Example 33 Screening of Preparation Methods for Pt-Based Catalyst Supports

[0158] The only difference between Example 33 and Example 29 is that in Example 33, polyhedral cerium oxide is prepared by a hydrothermal method. 2.25 g of sodium hydroxide is dissolved in 9.5 ml of ultrapure water for later use, 1.24 g of cerium nitrate hexahydrate is dissolved in 21.9 g of water, and added dropwise to the sodium hydroxide solution with continuous stirring. After the addition is complete, stirring is continued for 30 min, and then the liquid is poured into the lining of the crystallization reactor, sealed, and hydroheated at 90 ° C for 24 h. After the hydrothermal reaction is completed, the obtained solid is separated by suction filtration, washed with ultrapure water to pH = 7, and the filter cake is dried in a 100 ° C oven for 12 h, and then calcined in a muffle furnace at 400 ° C for 3 h to obtain polyhedral cerium oxide.

[0159] Table 6 Conversion rate of reaction substrate and molar yield of product in Examples 29-33

[0160]

[0161] Among them, C represents cerium oxide obtained by high-temperature thermal decomposition of cerium nitrate hexahydrate, and the calcination condition is 500°C for 5 hours; HC represents cubic cerium oxide prepared by a hydrothermal method; HR represents rod-shaped cerium oxide prepared by a hydrothermal method; HO represents octahedral cerium oxide prepared by a hydrothermal method; HP represents polyhedral cerium oxide prepared by a hydrothermal method.

[0162] From the results in Table 6, it can be seen that the cerium oxide-supported platinum-based catalysts prepared by different methods all have catalytic activity in the reaction of cyclohexanol to aniline, but the cerium oxide prepared by high-temperature thermal decomposition has the best effect.

[0163] Example 34 Screening of Calcination Temperatures for Cerium Oxide Supports of Pt-Based Catalysts

[0164] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 400°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0165] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0166] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0167] The measurement results are shown in Table 7.

[0168] Example 35 Screening of Calcination Temperatures for Cerium Oxide Supports of Pt-Based Catalysts

[0169] The only difference between Example 35 and Example 34 is that in Example 35, the thermal decomposition temperature when thermally decomposing cerium nitrate hexahydrate to obtain cerium oxide is 500°C.

[0170] Example 36 Screening of Calcination Temperatures for Cerium Oxide Supports of Pt-Based Catalysts

[0171] The only difference between Example 36 and Example 34 is that in Example 36, the thermal decomposition temperature when thermally decomposing cerium nitrate hexahydrate to obtain cerium oxide is 600°C.

[0172] Example 37 Screening of Calcination Temperatures for Cerium Oxide Supports of Pt-Based Catalysts

[0173] The only difference between Example 37 and Example 34 is that in Example 37, the thermal decomposition temperature when thermally decomposing cerium nitrate hexahydrate to obtain cerium oxide is 700°C.

[0174] Example 38 Screening of Calcination Temperatures for Cerium Oxide Supports of Pt-Based Catalysts

[0175] The only difference between Example 38 and Example 34 is that in Example 38, the thermal decomposition temperature when thermally decomposing cerium nitrate hexahydrate to obtain cerium oxide is 800°C.

[0176] Table 7 Conversion rate of reaction substrate and molar yield of product in Examples 34-38

[0177]

[0178] Among them, C-400, C-500, C-600, C-700, and C-800 represent the process of preparing cerium oxide by high-temperature thermal decomposition, with the calcination temperatures being 400°C, 500°C, 600°C, 700°C, and 800°C, respectively, and the calcination time being 5 hours.

[0179] The results in Table 7 demonstrate that during the high-temperature calcination process to prepare the ceria support, the calcination temperature significantly affects the support's performance, and a suitable calcination temperature is more conducive to the efficient production of aniline. Specifically, at calcination temperatures of 450°C to 500°C, the cyclohexanol conversion rate was 100%, and the molar yield of aniline was greater than 60%.

[0180] Example 39 Screening of Preparation Methods for Pt-Based Catalysts

[0181] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0182] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0183] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0184] The measurement results are shown in Table 8.

[0185] Example 40 Screening of Preparation Methods for Pt-Based Catalysts

[0186] The difference between Example 40 and Example 38 is that Example 40 adopts the excess impregnation method to prepare the Pt-based catalyst.

[0187] The preparation process of the Pt-based catalyst prepared by the excess impregnation method is as follows: the concentration of platinum in the platinum nitrate aqueous solution is 0.007g / ml, 2149 microliters of platinum nitrate aqueous solution is taken, 1g of cerium oxide is added, and stirred at room temperature overnight. Then, it is filtered and washed with deionized water. The resulting solid is dried in an oven at 100°C overnight, calcined in a muffle furnace at 500°C for 3h, and then reduced in a H2 / Ar mixed gas with a volume fraction of reducing gas of 10% and a gas flow rate of 60ml / min. -1 , the reduction temperature is 400℃ and the reduction time is 4h.

[0188] Example 41 Screening of Preparation Methods for Pt-Based Catalysts

[0189] The difference between Example 41 and Example 38 is that Example 41 adopts a deposition precipitation method to prepare the Pt-based catalyst.

[0190] The preparation process of the Pt-based catalyst by the deposition precipitation method is as follows: the concentration of platinum in the platinum nitrate aqueous solution is 0.006 g / ml, 2511 microliters of the platinum nitrate aqueous solution is taken, 1 g of cerium oxide is added, and stirred at room temperature for 2 hours, followed by dropwise addition of 0.2 mol / L sodium hydroxide solution to pH = 10. After the addition is completed, stirring is continued at room temperature overnight. The obtained solid is filtered, washed with deionized water, dried in an oven at 100°C overnight, calcined in a muffle furnace at 500°C for 3 hours, and then reduced in a H2 / Ar mixed gas with a volume fraction of 10% and a gas flow rate of 60 ml / min. -1 , the reduction temperature is 400℃ and the reduction time is 4h.

[0191] Table 8 Conversion rate of reaction substrate and molar yield of product in Examples 39-41

[0192]

[0193] Among them, 1 represents the platinum-based catalyst prepared by the equal volume impregnation method; 2 represents the platinum-based catalyst prepared by the excess impregnation method; and 3 represents the platinum-based catalyst prepared by the deposition precipitation method.

[0194] The results in Table 8 show that the platinum-based catalysts prepared by different preparation methods all have catalytic activity in the reaction of cyclohexanol to aniline. In comparison, the platinum-based catalyst prepared by the equal volume impregnation method has the best activity, with a cyclohexanol conversion rate of up to 100% and a molar yield of aniline higher than 70%.

[0195] Example 42: Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a batch reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0196] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0197] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0198] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0199] The measurement results are shown in Table 9.

[0200] Example 43: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0201] The main difference between Example 43 and Example 42 is that the organic reaction medium in Example 43 is p-xylene.

[0202] Example 44: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0203] The main difference between Example 44 and Example 42 is that the organic reaction medium in Example 44 is mesitylene.

[0204] Example 45: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0205] The main difference between Example 45 and Example 42 is that the organic reaction medium in Example 45 is ethylene glycol dimethyl ether.

[0206] Example 46: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0207] The main difference between Example 46 and Example 42 is that the organic reaction medium in Example 46 is cyclopentyl methyl ether.

[0208] Example 47: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0209] The main difference between Example 47 and Example 42 is that the reaction temperature in Example 47 is 160°C.

[0210] Example 48: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0211] The main difference between Example 48 and Example 42 is that the reaction temperature in Example 48 is 200°C.

[0212] Example 49: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0213] The main difference between Example 49 and Example 42 is that the reaction time in Example 49 is 8 hours.

[0214] Example 50 Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0215] The main difference between Example 50 and Example 42 is that the reaction time in Example 50 is 12 hours.

[0216] Example 51: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0217] The main difference between Example 51 and Example 42 is that the liquid ammonia pressure in Example 51 is 0.2 MPa.

[0218] Example 52: Pt-based catalyst catalyzes the conversion of cyclohexanol to aniline under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0219] The main difference between Example 52 and Example 42 is that the liquid ammonia pressure in Example 52 is 0.6 MPa.

[0220] Table 9 Conversion rate of reaction substrate and molar yield of product in Examples 42-52

[0221]

[0222] The results in Table 9 demonstrate that the novel aniline synthesis method provided herein is applicable to a variety of reaction media, and the corresponding target product can be obtained in various reaction media. By regulating factors such as the type of reaction medium, reaction temperature, reaction time, and reaction temperature, efficient conversion of cyclohexanol to aniline can be achieved over a suitable Pt-based catalyst, yielding the aniline product in relatively favorable yields. Specifically, when the reaction temperature is 180-200°C, the reaction time is 10-12 hours, and the pressure after liquid ammonia vaporization is 0.4-0.6 MPa, the cyclohexanol conversion rate reaches 100%, and the molar yield of aniline exceeds 50% in various reaction media.

[0223] Example 53: Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0224] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0225] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0226] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0227] The measurement results are shown in Table 10.

[0228] Example 54: Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0229] The only difference between Example 54 and Example 53 is that the reaction substrate in Example 54 is 2-methylcyclohexanol.

[0230] Example 55: Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0231] The only difference between Example 55 and Example 53 is that the reaction substrate in Example 55 is 2-methylcyclohexanol.

[0232] Example 56: Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0233] The only difference between Example 56 and Example 53 is that the reaction substrate in Example 56 is 2-methylcyclohexanol.

[0234] Example 57: Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0235] The only difference between Example 57 and Example 53 is that the reaction substrate in Example 57 is 2-methylcyclohexanol.

[0236] Example 58 Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0237] The only difference between Example 58 and Example 53 is that the reaction substrate in Example 58 is 2-methylcyclohexanol.

[0238] Example 59 Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0239] The only difference between Example 59 and Example 53 is that the reaction substrate in Example 59 is 2-methylcyclohexanol.

[0240] Example 60 Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0241] The only difference between Example 60 and Example 53 is that the reaction substrate in Example 60 is 2-methylcyclohexanol.

[0242] Example 61 Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0243] The only difference between Example 61 and Example 53 is that the reaction substrate in Example 61 is 2-methylcyclohexanol.

[0244] Example 62 Catalysis of different reaction substrates to aniline by Pt-based catalysts

[0245] The only difference between Example 62 and Example 53 is that the reaction substrate in Example 62 is 2-methylcyclohexanol.

[0246] Example 63: Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0247] The only difference between Example 63 and Example 53 is that the reaction substrate in Example 63 is 2-methylcyclohexanol.

[0248] Example 64: Catalytic activity of Pt-based catalysts on the conversion of different reaction substrates to aniline

[0249] The only difference between Example 64 and Example 53 is that the reaction substrate in Example 64 is 2-methylcyclohexanol.

[0250] Table 10 Conversion rate of reaction substrate and molar yield of product in Examples 53-64

[0251]

[0252] The results in Table 10 indicate that the novel aniline synthesis method provided by the present disclosure is applicable to the conversion of various cyclohexanol compounds with cyclohexanol as a structural unit into corresponding aromatic amines, and has relatively broad substrate applicability.

[0253] Example 65: Recycling of Platinum-Based Catalysts to Prepare Aniline from Cyclohexanol

[0254] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0255] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0256] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0257] The measurement results are shown in Table 11.

[0258] Example 66: Recycling of Platinum-Based Catalysts to Prepare Aniline from Cyclohexanol

[0259] The only difference between Example 66 and Example 65 is that the catalyst used in Example 65 was recycled in Example 66. Specifically, after the previous batch of experiments (i.e., Example 65) was completed, the organic reaction medium and catalyst were centrifuged and separated. The catalyst was then washed three times with toluene by repeated centrifugation before being re-applied to the next batch of reactions (i.e., Example 66). The substrate conversion and corresponding product yield of each example were measured.

[0260] Example 67: Recycling of Platinum-Based Catalysts to Prepare Aniline from Cyclohexanol

[0261] The only difference between Example 67 and Example 66 is that the catalyst used in Example 66 was recycled in Example 67. Specifically, after the previous batch of experiments (i.e., Example 66) was completed, the organic reaction medium and catalyst were centrifuged and separated. The catalyst was then washed three times with toluene by repeated centrifugation before being re-run in the next batch of reactions (i.e., Example 67). The substrate conversion and corresponding product yield of each example were measured.

[0262] Example 68: Recycling of Platinum-Based Catalysts to Prepare Aniline from Cyclohexanol

[0263] The only difference between Example 68 and Example 67 is that the catalyst used in Example 67 was recycled in Example 68. Specifically, after the previous batch of experiments (i.e., Example 67) was completed, the organic reaction medium and catalyst were centrifuged and then washed three times with toluene by repeated centrifugation. The catalyst was then re-applied to the next batch of reactions (i.e., Example 68) to determine the substrate conversion and corresponding product yield in each example.

[0264] Example 69: Recycling of Platinum-Based Catalysts to Prepare Aniline from Cyclohexanol

[0265] The only difference between Example 69 and Example 68 is that the catalyst used in Example 68 was recycled in Example 69. Specifically, after the previous batch of experiments (i.e., Example 68) was completed, the organic reaction medium and catalyst were centrifuged and separated. The catalyst was then washed three times with toluene by repeated centrifugation before being re-applied to the next batch of reactions (i.e., Example 69). The substrate conversion and corresponding product yield of each example were measured.

[0266] Example 70: Recycling of Platinum-Based Catalysts to Prepare Aniline from Cyclohexanol

[0267] The only difference between Example 70 and Example 69 is that the catalyst used in Example 69 was recycled in Example 70. Specifically, after the previous batch of experiments (i.e., Example 69) was completed, the organic reaction medium and the catalyst were centrifuged and separated. The catalyst was then repeatedly centrifuged and washed three times with toluene, dried in a 100°C oven, and then calcined in a muffle furnace at 500°C for 3 hours. The resulting solid was reduced in a 10% H2 / Ar mixture at a temperature of 400°C for 2 hours. The reaction was then repeated for a sixth time, and the next batch of reactions (i.e., Example 70) was repeated to determine the substrate conversion and corresponding product yield in each example.

[0268] Table 11 Conversion rate of reaction substrate and molar yield of product in Examples 65-70

[0269]

[0270]

[0271] Among them, 6* represents that after the fifth cycle, the catalyst was washed three times with toluene and then dried in a 100°C oven, and then calcined at 500°C in a muffle furnace for 3 hours. The resulting solid was reduced at high temperature in a 10% H2 / Ar mixture at a reduction temperature of 400°C for 2 hours, and then the sixth cycle was applied.

[0272] The results in Table 11 demonstrate that the catalyst exhibits a certain degree of cyclic stability and maintains a certain ability to produce aniline after five cycles. After slight deactivation, the catalyst can be regenerated by calcination-reduction to restore its original activity. Therefore, the catalysts of the present invention exhibit good cyclic stability and can be reused multiple times, thereby further reducing the cost of preparing aniline from cyclohexanol.

[0273] Example 71 Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0274] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0275] When a platinum-based catalyst is used to catalyze the preparation of aniline from cyclohexanol: the reaction is carried out in a fixed bed, the reaction raw material is a toluene solution of cyclohexanol, wherein the cyclohexanol concentration is 0.2 mmol / ml, the flow rate is 0.05 ml / min, 0.5 g of catalyst is loaded into the reaction tube, the NH3 flow rate is 100 ml / min, the pressure of the liquid ammonia after vaporization is 0.4 MPa, the reaction temperature is 160°C, and the reaction time is 10 h.

[0276] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0277] The measurement results are shown in Table 12.

[0278] Example 72 Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0279] The only difference between Example 72 and Example 71 is that the reaction temperature in Example 72 is 180°C.

[0280] Example 73: Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0281] The only difference between Example 73 and Example 71 is that the reaction temperature in Example 73 is 200°C.

[0282] Example 74: Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0283] The only difference between Example 74 and Example 71 is that the reaction temperature in Example 74 is 220°C.

[0284] Example 75: Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times.

[0285] The only difference between Example 75 and Example 71 is that the reaction temperature in Example 75 is 180°C and the liquid ammonia pressure is 0.2 MPa.

[0286] Example 76: Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0287] The only difference between Example 76 and Example 71 is that the reaction temperature in Example 76 is 180°C and the liquid ammonia pressure is 0.6 MPa.

[0288] Example 77: Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0289] The only difference between Example 77 and Example 71 is that the reaction temperature in Example 77 is 180° C. and the cyclohexanol flow rate is 0.1 ml / min.

[0290] Example 78 Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0291] The only difference between Example 78 and Example 71 is that the reaction temperature in Example 78 is 180° C. and the cyclohexanol flow rate is 0.2 ml / min.

[0292] Example 79: Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor under various organic reaction media, liquid ammonia pressures, reaction temperatures, and reaction times

[0293] The only difference between Example 79 and Example 71 is that the reaction temperature in Example 79 is 180° C. and the cyclohexanol flow rate is 0.4 ml / min.

[0294] Table 12 Conversion rate of reaction substrate and molar yield of product in Examples 71-79

[0295]

[0296]

[0297] The results in Table 12 show that the aniline synthesis method can also be applied to a fixed-bed reactor. In a fixed-bed reactor, the reaction temperature, the flow rate of the reactants, and the ammonia pressure all have an impact on substrate conversion and product formation. When the reaction temperature is 180-200°C, the flow rate of the cyclohexane is 0.05-0.1 ml / min, and the NH3 pressure is 0.2-0.4 MPa, the aniline product can be obtained in a relatively high yield in the fixed-bed reactor. The yield is significantly higher than that in a tank reactor. This shows that the synthesis method has certain industrial application prospects.

[0298] Example 80 Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor at various reaction times

[0299] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 484 microliters of a platinum nitrate aqueous solution with a concentration of 0.031g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes and dry in an oven at 100°C overnight. After grinding and crushing, calcinate at high temperature in a muffle furnace, specifically calcinate at 500°C for 5h. The volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0300] When using a platinum-based catalyst to catalyze the preparation of aniline from cyclohexanol: the reaction is carried out in a fixed bed, the reaction raw material is a toluene solution of cyclohexanol, wherein the cyclohexanol concentration is 0.2 mmol / ml, the flow rate is 0.05 ml / min, 0.5 g of catalyst is loaded into the reaction tube, the NH3 flow rate is 100 ml / min, the pressure of the liquid ammonia after vaporization is 0.4 MPa, the reaction temperature is 160°C, and the reaction time is 5 hours.

[0301] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0302] The measurement results are shown in Table 13.

[0303] Example 81 Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0304] The only difference between Example 81 and Example 80 is that in Example 81, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 10 hours.

[0305] Example 82: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0306] The only difference between Example 82 and Example 80 is that in Example 82, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 15 hours.

[0307] Example 83: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0308] The only difference between Example 83 and Example 80 is that in Example 83, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 20 hours.

[0309] Example 84: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0310] The only difference between Example 84 and Example 80 is that in Example 84, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 25 hours.

[0311] Example 85: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0312] The only difference between Example 85 and Example 80 is that in Example 85, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 30 hours.

[0313] Example 86: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0314] The only difference between Example 86 and Example 80 is that in Example 86, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 35 hours.

[0315] Example 87: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0316] The only difference between Example 87 and Example 80 is that in Example 87, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 40 hours.

[0317] Example 88: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0318] The only difference between Example 88 and Example 80 is that in Example 88, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 45 hours.

[0319] Example 89: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0320] The only difference between Example 89 and Example 80 is that in Example 89, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 50 hours.

[0321] Example 90 Catalytic conversion of cyclohexanol to aniline over a Pt-based catalyst in a fixed bed reactor at various reaction times

[0322] The only difference between Example 90 and Example 80 is that in Example 90, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 60 hours.

[0323] Example 91: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0324] The only difference between Example 91 and Example 80 is that in Example 91, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 70 hours.

[0325] Example 92: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0326] The only difference between Example 92 and Example 80 is that in Example 92, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 80 hours.

[0327] Example 93: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0328] The only difference between Example 93 and Example 80 is that in Example 93, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 90 hours.

[0329] Example 94: Catalytic conversion of cyclohexanol to aniline using a Pt-based catalyst in a fixed bed reactor at various reaction times

[0330] The only difference between Example 94 and Example 80 is that in Example 94, the reaction time for preparing aniline from cyclohexanol using a platinum-based catalyst is 100 hours.

[0331] Table 13 Conversion rate of reaction substrate and molar yield of product in Examples 80-94

[0332]

[0333] The results in Table 13 show that in the aniline synthesis method, the selected Pt-based catalyst exhibits good stability. No obvious deactivation is observed after reaction for more than 30 h up to 100 h, and the aniline yield can still be maintained above 81%, further indicating that the aniline synthesis method catalyzed by this catalyst has good application prospects.

[0334] Comparative Example 1

[0335] The active ingredient in the catalyst in Comparative Example 1 is Fe, and an aqueous solution of iron nitrate is used as a precursor.

[0336] The platinum-based catalyst was prepared by the equal volume impregnation method. The platinum loading in the platinum-based catalyst was 1.5wt%. Cerium oxide obtained by thermal decomposition of cerium nitrate hexahydrate at 500°C was used as a carrier. The preparation process of the platinum-based catalyst is as follows: take 500 microliters of an aqueous solution of iron nitrate (also known as an aqueous solution of Fe(NO3)2) with an iron concentration of 0.030g / ml, add 1g of cerium oxide, and stir continuously. Then, ultrasonicate for 10-20 minutes, dry in an oven at 100°C overnight, grind and crush, and calcine at high temperature in a muffle furnace, specifically calcine at 500°C for 5h, the volume fraction of hydrogen in the reducing gas is 10%, and the reducing gas flow rate is 60ml / min. -1 The reduction time is 4 h and the reduction temperature is 400 °C.

[0337] When cyclohexanol is catalyzed by a platinum-based catalyst to prepare aniline: the reaction substrate is 0.10g of cyclohexanol, the catalyst is 0.05g of a platinum-based catalyst, 5ml of toluene is the reaction medium, the pressure after liquid ammonia vaporization is 0.4MPa, the reaction temperature is 180°C, the reaction time is 10h, a batch reactor is used, and the reaction product is aniline.

[0338] The conversion rate of the reaction substrate and the yield of the reaction product were determined. The determination method was as follows: the reaction product was subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) using an HP-5 chromatographic column. The column temperature program conditions were: 50°C for 10 mins, and 10°C / min for 10 min. -1 The temperature was raised to 250° C. at a rate of 100° C. and maintained at 250° C. for 5 minutes. The reaction substrate conversion rate and the product molar yield were calculated based on the measured molar amount of the reaction substrate and the molar yield of aniline, and the molar amount of the reaction substrate input and the theoretical molar yield of aniline, respectively.

[0339] The measurement results are shown in Table 14.

[0340] Comparative Example 2

[0341] Comparative Example 2 differs from Comparative Example 1 only in that the active ingredient in the catalyst in Comparative Example 2 is Co, and a cobalt nitrate aqueous solution (i.e., Co(NO3)2 aqueous solution) is used as the precursor. The cobalt concentration in the cobalt nitrate aqueous solution is 0.0.032 g / ml, and the solution volume is 469 μL.

[0342] Comparative Example 3

[0343] Comparative Example 3 differs from Comparative Example 1 only in that the active ingredient in the catalyst in Comparative Example 3 is Co, and a nickel nitrate aqueous solution (i.e., a Ni(NO3)2 aqueous solution) is used as the precursor. The nickel concentration in the nickel nitrate aqueous solution is 0.0.028 g / ml, and the solution volume is 536 μl.

[0344] Comparative Example 4

[0345] Comparative Example 4 differs from Comparative Example 1 only in that the active ingredient in the catalyst in Comparative Example 4 is Pd, and a Pd nitrate aqueous solution (i.e., a Pd(NO3)2 aqueous solution) is used as the precursor. The Pd concentration in the Pd nitrate aqueous solution is 0.029 g / ml, and the solution volume is 517 μL.

[0346] Comparative Example 5

[0347] Comparative Example 5 differs from Comparative Example 1 only in that the active ingredient in the catalyst in Comparative Example 5 is Ru, and a Ru chlorate aqueous solution (i.e., RuCl3 aqueous solution) is used as the precursor. The cobalt concentration in the Ru nitrate aqueous solution is 0.031 g / ml, and the solution volume is 484 μL.

[0348] Table 14 Conversion rate of reaction substrate and molar yield of product in comparative examples 1-5

[0349]

[0350] The results show that the ability of catalysts based on other transition metal elements to convert the substrate cyclohexanol is significantly lower than that of platinum-based catalysts, that is, Pt-based catalysts have higher dehydrogenation activity under the same conditions; at the same time, compared with Pt-based catalysts, the performance of other transition metal element catalysts in generating aniline is poor.

[0351] This disclosure provides a novel method for synthesizing aniline. Compared to conventional methods, this method utilizes cyclohexanol as a raw material, which is both inexpensive and readily available. Cyclohexanol can also be obtained from renewable biomass, avoiding the limitations of conventional methods that rely on increasingly depleted fossil fuels such as benzene, toluene, and xylene as raw materials. Furthermore, the entire reaction pathway produces water as a major byproduct and requires no additives, thus avoiding the production of environmentally harmful substances and providing a green and environmentally friendly approach. Furthermore, the reaction itself proceeds without an external hydrogen source, and the reuse of hydrogen in the cyclohexanol enables this synthesis method to achieve higher atomic utilization and atom economy. The resulting product, aniline, is one of the most important amine compounds and is widely used in the production of pharmaceuticals, dyes, agricultural chemicals, and various polymers, possessing extremely high added value. In addition, this synthesis method can be applied to both autoclave reactors and fixed-bed reactors. Aniline can be obtained in relatively considerable yields in different reactors. Especially in the fixed-bed reactor, the selected catalyst shows good stability, and aniline can be obtained stably at a high yield even during long-term operation. The above shows that the new synthesis method of aniline catalyzed by this catalyst has certain advantages and good industrial application prospects.

[0352] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Within the scope of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of simplicity.

[0353] While the disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art in light of the foregoing description.

[0354] The embodiments of the present disclosure are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A method for synthesizing aniline, characterized in that, include: A cyclohexanol compound and liquid ammonia react in an organic reaction medium at 160-250° C. under the action of a Pt-based catalyst to obtain aniline; the cyclohexanol compound is cyclohexanol; The Pt-based catalyst includes a carrier and Pt loaded on the carrier; the particle size of Pt is 1-20 nm; the carrier is selected from cerium oxide, and the cerium oxide is prepared by thermally decomposing cerium nitrate hexahydrate; the thermal decomposition temperature is 400°C to 600°C.

2. The method for synthesizing aniline according to claim 1, wherein The Pt precursor supported on the carrier is selected from at least one of an aqueous solution of platinum nitrate, a methanol solution of platinum nitrate, an aqueous solution of chloroplatinic acid, a n-butanol solution of platinum nitrate, and a methanol solution of chloroplatinic acid.

3. The method for synthesizing aniline according to claim 1, characterized in that The organic reaction medium is selected from at least one of toluene, m-xylene, p-xylene, mesitylene, ethylene glycol dimethyl ether and cyclopentyl methyl ether.

4. The method for synthesizing aniline according to claim 1, wherein The molar ratio of the cyclohexanol compound to Pt is 1:(0.002-0.01); And / or, the mass ratio of the cyclohexanol compound to the organic reaction medium is 1:(1-50); and / or, the pressure of the liquid ammonia after gasification is 0.1-1 MPa; and / or, the reaction temperature is 180-200° C.; And / or, the reaction time is 1-24h; And / or the reaction medium is selected from toluene or p-xylene.

5. The method for synthesizing aniline according to claim 1, characterized in that: The preparation method of the Pt-based catalyst comprises: Providing the carrier; the water absorption rate of the carrier is 50% to 765%; Providing a precursor solution; the concentration of the precursor solution is 0.022 g / ml to 0.050 g / ml, and the volume is 298 μL to 682 μL; pouring the support into the precursor solution, drying and calcining; The calcined product is reduced in a reducing gas.

6. The method for synthesizing aniline according to claim 5, characterized in that: The calcination temperature is 400° C. to 500° C.; and the calcination time is 5 hours to 8 hours.

7. The method for synthesizing aniline according to claim 5, characterized in that: The reducing gas is a mixed gas of hydrogen and argon, wherein the volume fraction of hydrogen is 10%-20%, the flow rate of the reducing gas is 30ml / min-80ml / min, and the reduction time is 3-4h.

8. The method for synthesizing aniline according to claim 5, characterized in that: The reduction temperature is 300℃~400℃.

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