A nanomaterial, a preparation method and application thereof

Abstract

The present disclosure relates to a kind of nanomaterial and its preparation method and application, the method includes: (1) the graphite shaped body is placed in the electrolyte containing longest chain carbon atom number 1-8 organic base electrolysis obtains the first mixture containing carbon dot and organic base;(2) silicon source is mixed with the first mixture, obtains the second mixture;(3) the second mixture is carried out hydrothermal reaction in heat-resistant closed container;(4) after the reaction product obtained by hydrothermal is cooled, solid-liquid separation is carried out, obtains solid phase product and liquid phase product, the solid phase product is carried out first heat treatment, obtains nanomaterial;(5) the liquid phase product is contacted with porous material, the pore size of the porous material is greater than 0.7nm;(6) the porous material after contact is carried out second heat treatment.The present disclosure nanomaterial is used for oxime rearrangement reaction, and higher oxime conversion rate and amide selectivity are obtained at relatively lower temperature, and the wastewater generated by nanomaterial preparation reaches the standard that can be directly discharged.

Description

Technical Field

[0001] This disclosure relates to a nanomaterial, its preparation method, and its application. Background Technology

[0002] Research on green catalytic oxidation materials began in the early 1980s. These materials not only possess catalytic oxidation properties but also exhibit shape selectivity and superior stability. However, the wastewater from the production of high-silicon green catalytic materials contains organic template agents and has a high COD content, typically ranging from 500 to 50,000 mg / L, making it difficult to treat biochemically and unsuitable for direct discharge into conventional biological wastewater treatment units. This limits the production of high-silicon green catalytic materials, necessitating a new technology for their direct discharge. Carbon nanomaterials are similar to ordinary nanomaterials but possess unique properties such as quantum size effects, small size effects, and macroscopic quantum tunneling effects in optics, electricity, and magnetism. The academic community now refers to carbon nanoparticles smaller than 10 nm as carbon quantum dots (CDs), which are novel small-sized carbon nanomaterials. Due to their excellent fluorescence properties, CDs are increasingly being studied, and they can also be applied to energy issues, environmental protection, photovoltaic devices, and other related fields. Applying CDs to the preparation of green catalytic oxidation materials to improve their production is currently one of the key research areas for CD applications. Summary of the Invention

[0003] The purpose of this disclosure is to provide a nanomaterial, its preparation method, and its application. The nanomaterial prepared by this method not only has good catalytic performance, but also achieves high oxime conversion and amide selectivity at relatively low temperatures in the reaction for oxime rearrangement to prepare amides. Furthermore, the wastewater generated by this nanomaterial preparation method can directly meet the discharge standards.

[0004] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing nanomaterials, the method comprising:

[0005] (1) Electrolyze the graphite molded body in an electrolyte containing 1-8 carbon atoms of the longest chain to obtain a first mixture containing carbon dots and organic base;

[0006] (2) The silicon source is mixed with the first mixture to obtain a second mixture;

[0007] (3) The second mixture is subjected to a hydrothermal reaction in a heat-resistant sealed container;

[0008] (4) After cooling the reaction product obtained after hydrothermal treatment, solid-liquid separation is performed to obtain solid product and liquid product. The solid product is subjected to a first heat treatment to obtain nanomaterials.

[0009] (5) The liquid phase product is brought into contact with a porous material, wherein the pore size of the porous material is greater than 0.7 nm;

[0010] (6) The porous material after contact is subjected to a second heat treatment.

[0011] Optionally, in step (1), the electrolysis voltage is 15-45V and the time is 1-10 days;

[0012] Optionally, in the first mixture, the content of the carbon dots is 5-1000 mg / L, and the concentration of the organic base is 50-2000 mmol / L;

[0013] Optionally, the size of the carbon dots is 3-6 nm.

[0014] Optionally, in step (2), the weight ratio of the first mixture to the amount of the silicon source is 100:(1-80).

[0015] Optionally, in step (3), the conditions for the hydrothermal reaction include: a temperature of 100-200℃ and a time of 6-144h.

[0016] Optionally, in step (4), the first heat treatment of the solid product includes: sequentially subjecting the solid product to a first calcination and a second calcination;

[0017] Optionally, the conditions for the first calcination include: 200-500℃, time of 2-24h, and an inert atmosphere;

[0018] Optionally, the conditions for the second calcination include: 400-800℃, time of 1-12h, and air atmosphere.

[0019] Optionally, in step (5), the weight ratio of the liquid phase product to the porous material is 1000:(1-500);

[0020] Optionally, the contact conditions include: a time of 5-720 min and a temperature of 20-100℃;

[0021] Optionally, the porous material is selected from one or more of MOR molecular sieves, Y molecular sieves, β molecular sieves, mesoporous molecular sieves, carbon nanotubes, and activated carbon.

[0022] Optionally, in step (6), the conditions for the second heat treatment include: a time of 1-8 hours, a temperature of 500-800°C, and an air atmosphere.

[0023] Optionally, the organic base with the longest chain having 1-8 carbon atoms is selected from one or more of urea, quaternary ammonium bases with the longest chain having 1-8 carbon atoms, aliphatic amines with 1-6 carbon atoms, and alkanolamines with 1-6 carbon atoms.

[0024] Optionally, the quaternary ammonium base compound with the longest chain having 1-8 carbon atoms is tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, or a combination of two or three of them;

[0025] Optionally, the aliphatic amine compound having 1-6 carbon atoms is ethylamine, ethylenediamine, n-butylamine, butanediamine or hexanediamine, or a combination of two or three of them;

[0026] Optionally, the alkanolamine compound having 1-6 carbon atoms is monoethanolamine, diethanolamine, or triethanolamine, or a combination of two or three of them;

[0027] The silicon source is an organic silicon source and / or an inorganic silicon source;

[0028] Optionally, the organosilicon source is selected from tetramethyl silicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, or dimethoxydiethoxysilane, or a combination of two or three of them.

[0029] Optionally, the inorganic silicon source is silica sol and / or silica gel.

[0030] The second aspect of this disclosure provides nanomaterials prepared using the method described in the first aspect of this disclosure.

[0031] This disclosure provides a third aspect regarding the application of the nanomaterials described in the second aspect of this disclosure in the preparation of amides from oxime rearrangements.

[0032] The method disclosed herein is simple and suitable for industrial production. The nanomaterials prepared by this method have uniformly distributed active centers and superior catalytic activity. When used in the oxime rearrangement to prepare amides, it can achieve high raw material conversion rate and target product selectivity at relatively low temperatures. Furthermore, the wastewater generated during the preparation of nanomaterials can be directly discharged, and the porous materials can be reused.

[0033] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0034] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of this disclosure.

[0035] The first aspect of this disclosure provides a method for preparing nanomaterials, the method comprising:

[0036] (1) Electrolyze the graphite molded body in an electrolyte containing 1-8 carbon atoms of the longest chain to obtain a first mixture containing carbon dots and organic base;

[0037] (2) The silicon source is mixed with the first mixture to obtain a second mixture;

[0038] (3) The second mixture is subjected to a hydrothermal reaction in a heat-resistant sealed container;

[0039] (4) After cooling the reaction product obtained by hydrothermal treatment, solid-liquid separation is performed to obtain solid product and liquid product. The solid product is subjected to a first heat treatment to obtain nanomaterials.

[0040] (5) The liquid phase product is brought into contact with a porous material, wherein the pore size of the porous material is greater than 0.7 nm;

[0041] (6) The porous material after contact is subjected to a second heat treatment.

[0042] The wastewater from the preparation of nanomaterials using the method disclosed herein can directly meet discharge standards. The nanomaterials prepared by this method have a more uniform distribution of active centers, better accessibility of active centers, and better reproducibility, making them suitable for industrial production.

[0043] In this disclosure, the second mixture contains only a silicon source, an organic base, carbon dots, and an electrolyte, and does not contain any other substances.

[0044] In this disclosure, step (1) is specifically performed as follows: a graphite molded body and a conductive material, respectively connected to the positive and negative terminals of a DC power supply, are placed in an electrolyte containing an organic base with 1-8 carbon atoms in its longest chain. Electrolysis is carried out at 15-45V for 1-10 days to obtain a first mixture containing carbon dots and an organic base. The carbon dots have a size of 3-6 nm. The "size of the carbon dot" refers to the maximum distance between any two points on the carbon dot particle. Generally, carbon dots are approximately spherical, so the size of the carbon dot is generally equal to the diameter of its approximately spherical particle. Since the sizes of different carbon dots may vary slightly, the size of the carbon dot generally refers to its average size. When the size of the carbon dots meets the above range, they have better interaction with the organic base, resulting in a uniform distribution of active centers in the obtained nanomaterial, exhibiting superior catalytic activity. When used in the oxime rearrangement to prepare amides, it can achieve higher raw material conversion rates and target product selectivity at relatively low temperatures.

[0045] In this disclosure, the electrolyte is well known to those skilled in the art, such as an aqueous solution. There is no specific limitation on the amount of electrolyte used, and it can be selected according to actual needs, such as the size of the graphite molded body and the electrolysis conditions.

[0046] In this disclosure, in step (1), the graphite molded body can be a graphite rod or a graphite plate. The diameter of the graphite rod can be 2-20 mm, and the length can be 2-100 cm, where the length refers to the axial length of the graphite rod. The length of the graphite plate can be 5-100 cm, the width can be 1-100 cm, and the thickness can be 0.01-10 mm. There are no specific restrictions on the type and shape of the conductive material; it can be any conductive material, such as iron, copper, graphite, etc., preferably graphite. The shape can be rod-shaped, plate-shaped, etc., preferably rod-shaped. During electrolysis, a certain distance needs to be maintained between the graphite molded body and the conductive material, for example, 3-10 cm.

[0047] In this disclosure, "longest chain" refers to the chain with the most carbon atoms, for example, the longest chain of tetrabutylammonium hydroxide has 8 carbon atoms. Organic bases with the longest chain having 1-8 carbon atoms are well known to those skilled in the art, and may be selected from, for example, urea, quaternary ammonium bases with the longest chain having 1-8 carbon atoms, aliphatic amines with 1-6 carbon atoms, and one or more alkanolamines with 1-6 carbon atoms.

[0048] According to one embodiment of this disclosure, the general molecular formula of a quaternary ammonium base compound with the longest chain having 1-8 carbon atoms can be (R 1 )4NOH, where R 1 It may be selected from at least one straight-chain alkyl group of C1-C4 and branched alkyl group of C3-C4. Preferably, the quaternary ammonium base compound with the longest chain having 1-8 carbon atoms may be tetraethylammonium hydroxide, tetrapropylammonium hydroxide or tetrabutylammonium hydroxide, or a combination of two or three of them.

[0049] According to one embodiment of this disclosure, the general molecular formula of aliphatic amine compounds having 1-6 carbon atoms can be R. 2 (NH2) n , where R 2 It can be a C1-C6 alkyl or alkylene group, where n is any integer from 1 to 3. Preferably, the aliphatic amine compound having 1-6 carbon atoms can be ethylamine, ethylenediamine, n-butylamine, butanediamine, or hexamethylenediamine, or a combination of two or three of them.

[0050] According to one embodiment of this disclosure, the general molecular formula of an alcoholamine compound having 1-6 carbon atoms can be (HOR) 3 ) m NH (3-m), where R 3 It can be a C1-C4 alkyl group, where m is an integer of 1, 2, or 3. Preferably, the alkanolamine compound having 1-6 carbon atoms can be monoethanolamine, diethanolamine, or triethanolamine, or a combination of two or three of them.

[0051] According to one embodiment of this disclosure, the silicon source can be an organosilicon source and / or an inorganic silicon source; preferably, the organosilicon source is selected from tetramethyl silicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate or dimethoxydiethoxysilane, or a combination of two or three of them; preferably, the inorganic silicon source is silica sol and / or silica gel.

[0052] According to one embodiment of this disclosure, the porous material can be a molecular sieve with a porous structure that has adsorption properties and / or porous carbon, preferably selected from one or more of MOR molecular sieves, Y molecular sieves, β molecular sieves, mesoporous molecular sieves, carbon nanotubes and activated carbon, wherein the Y molecular sieve can be, for example, NaY molecular sieve, and the mesoporous molecular sieve can be, for example, mesoporous MCM-41 molecular sieve.

[0053] According to one embodiment of this disclosure, in step (1), the concentrations of carbon dots and organic bases in the first mixture can vary within a wide range. For example, the concentration of carbon dots in the first mixture is 5-1000 mg / L, preferably 10-500 mg / L; the concentration of organic bases is 50-2000 mmol / L, preferably 100-1000 mmol / L. The content of carbon dots in the first mixture can be measured by methods such as evaporation and weighing.

[0054] According to one embodiment of this disclosure, in step (2), the weight ratio of the first mixture to the silicon source can vary within a wide range. The weight ratio of the first mixture to the silicon source can be 100:(1-80), preferably 100:(5-60), and more preferably 100:(10-40). Nanomaterials prepared within the above-mentioned ratio range have a better distribution of active centers, which is beneficial for further improving their catalytic performance.

[0055] According to one embodiment of the present disclosure, in step (2), there is no specific limitation on the mixing temperature and time. In one specific embodiment, the mixing temperature can be 10-60°C and the mixing time can be 1-10h. The mixing time refers to the time for mixing the slurry after the silicon source and the first mixture are doped to form a slurry.

[0056] According to one embodiment of this disclosure, in step (3), the heat-resistant sealed container is well known to those skilled in the art, for example, a polytetrafluoroethylene reactor. There are no particular limitations on the pressure of the hydrothermal reaction process; it can be the system's own pressure or under additional applied pressure. Preferably, the hydrothermal reaction process is carried out under its own pressure (typically in a sealed container). In a preferred embodiment, the second mixture is subjected to a hydrothermal reaction at 100-200°C for 6-144 hours; more preferably, the second mixture is subjected to a hydrothermal reaction at 120-180°C for 12-96 hours.

[0057] According to one embodiment of this disclosure, the product obtained from the hydrothermal reaction is filtered, washed, dried, and calcined to collect a solid product. The washing solution can be deionized water, ethanol, etc.; the drying can be carried out in a constant temperature drying oven, with drying conditions including a temperature of 100-200°C and a time of 1-48 hours.

[0058] According to one embodiment of this disclosure, step (4), the first heat treatment of the solid product includes: sequentially subjecting the solid product to a first calcination and a second calcination; the first calcination temperature can be 200-500℃, the time is 2-24h, and an inert atmosphere is used; preferably, the temperature is 250-450℃, and the time is 4-12h; the second calcination temperature is 400-800℃, the time is 1-12h, and an air atmosphere is used; preferably, the temperature is 450-750℃, and the time is 2-6h; the inert atmosphere is well known to those skilled in the art, for example, it can be an oxygen-free atmosphere, and the gas in the inert atmosphere can be one or more of helium, argon, nitrogen, and carbon dioxide. Calcination can be carried out in a muffle furnace or a tube furnace; other specific calcination methods will not be described here.

[0059] According to one embodiment of this disclosure, in step (5), the weight ratio of the liquid product to the porous material is 1000:(1-500); preferably 1000:(10-100). The amount of porous material processed is 2-1000 kg of liquid product relative to 1 kg of porous material.

[0060] According to one embodiment of this disclosure, in step (5), the contact conditions include: a time of 5-720 min and a temperature of 20-100℃; preferably, the COD content of the liquid product obtained after contacting the liquid product and the porous material is less than 50 ppm; in the method of this disclosure, by contacting the liquid product with the porous material to remove pollutants such as organic ammonia nitrogen in the liquid product, the wastewater in the preparation of nanomaterials is cleanly discharged, which is beneficial to the clean industrial application of the method of this invention.

[0061] According to one embodiment of this disclosure, in step (6), the second heat treatment is calcination, with conditions including: time of 1-8 hours, temperature of 500-800°C, and an air atmosphere. Calcination can be carried out in a calcination furnace. The calcined porous material can be returned to step (5) for repeated recycling.

[0062] According to one embodiment of the present disclosure, in step (6), before the second heat treatment, the porous material is dried, for example by introducing the contacted porous material into flash drying.

[0063] The second aspect of this disclosure provides nanomaterials prepared using the method described in the first aspect of this disclosure.

[0064] In the methods disclosed herein, the pore size of porous materials and nanomaterials refers to the size of the pores on the outer surface of the material, i.e., the pore size of the pores exposed on the outer surface of the material. It is generally measured by the maximum distance between any two points of the pore, which is known to those skilled in the art. It can be obtained through existing data, calculated by XRD method or obtained by high-resolution electron microscopy characterization and statistical analysis. The pore size of porous materials and nanomaterials prepared by the present invention can be obtained.

[0065] According to one embodiment of this disclosure, the pore size of the nanomaterial can be 0.3-5.0 nm, preferably 0.5-1.0 nm.

[0066] This disclosure provides a third aspect regarding the application of the nanomaterials described in the second aspect of this disclosure in the preparation of amides from oxime rearrangements.

[0067] In a preferred embodiment, the present invention provides the application of nanoporous materials in the preparation of caprolactam from cyclohexanone oxime rearrangement, which can achieve better raw material conversion and product selectivity at relatively low reaction temperatures (e.g., 300-330°C).

[0068] According to one embodiment of this disclosure, the reaction of cyclohexanone oxime rearrangement to prepare caprolactam is carried out in a fixed-bed reactor in the presence of a solvent at a pressure of atmospheric pressure to 1 MPa and a temperature of 280-380°C. The solvent may be one or more of methanol, acetone, ethanol, and cyclohexane, and the weight ratio of cyclohexanone oxime to solvent is 1:(2-200); the weight hourly space velocity of cyclohexanone oxime is 1-500 h⁻¹. -1 Alternatively, the weight ratio of cyclohexanone oxime to catalyst can be 100:(1-10000), the feed rate of cyclohexanone oxime can be 1-10000 g / h, and the reaction time can be 2-48 h.

[0069] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0070] All reagents used in this invention are commercially available analytical grade reagents.

[0071] COD was tested according to the national standard GB11914-89, Method for Determination of Chemical Oxygen Demand.

[0072] The aperture size was measured using XRD, and the X-ray diffraction (XRD) was performed on the sample phase analysis using a Rigaku D / MaxA-ⅢA X-ray diffractometer. Test conditions: Cu target, Kα radiation, Ni filter, tube voltage 30kV, tube current 20mA, step scan, scan range 5°-80°.

[0073] The method for testing the carbon point content in the first mixture was the dry weighing method using a RE-2L rotary evaporator.

[0074] Method for testing the size of carbon dots: TEM, under a magnification of 100,000 to 1,000,000 times, randomly measure the size of 100 carbon dots and obtain the average size of the carbon dots.

[0075] Example 1

[0076] (1) Add 1000 mL of tetrapropylammonium hydroxide aqueous solution to a beaker, place two identical graphite rods (8 mm in diameter and 50 cm in length) in it, keeping the distance between the graphite rods at 8 cm, connect the graphite rods to the positive and negative terminals of a DC power supply respectively, and electrolyze at 30 V for 5 days to obtain a first mixture containing organic base and carbon dots; the concentration of carbon dots in the first mixture is 120 mg / L, and the concentration of tetrapropylammonium hydroxide is 650 mmol / L;

[0077] (2) Add tetraethyl orthosilicate to 100 mL of the first mixture and mix at 50 °C for 6 h to obtain the second mixture, wherein the weight ratio of the first mixture to tetraethyl orthosilicate is 100:35.

[0078] (3) The second mixture was transferred to a stainless steel reactor with a polytetrafluoroethylene liner and subjected to a hydrothermal reaction at 170°C for 72 h to obtain the hydrothermal reaction product. The hydrothermal reaction product was cooled and removed and filtered. The solid product was washed with water and dried at 110°C for 3 h. Then, it was first calcined at 350°C for 12 h in a nitrogen atmosphere and then calcined at 600°C for 3 h in an air atmosphere to obtain nanomaterial A.

[0079] (4) Collect the liquid phase product after solid-liquid separation and contact it with β molecular sieve (pore size of 0.7nm) at room temperature (20℃, the same below) for 6 hours. The mass ratio of liquid phase product to β molecular sieve is 15:1. The COD of the clear liquid after contact is less than 50ppm and can be directly discharged.

[0080] (5) After contacting the β molecular sieve, dry it at 110°C for 3 hours and then calcine it at 600°C for 3 hours in air atmosphere to obtain the calcined β molecular sieve for later use.

[0081] Example 2

[0082] (1) Add 1000 mL of triethanolamine aqueous solution to a beaker, place the anode graphite rod (8 mm in diameter and 50 cm in length) and the cathode graphite rod (8 mm in diameter and 50 cm in length) in it, keep the distance between the anode graphite rod and the cathode rod at 10 cm, connect the anode graphite rod to the positive terminal of the DC power supply and connect the cathode rod to the negative terminal of the DC power supply, electrolyze at 45 V for 4 days to obtain a first mixture containing organic base and carbon dots; the concentration of carbon dots in the first mixture is 100 mg / L and the concentration of triethanolamine is 800 mmol / L;

[0083] (2) Add tetraethyl orthosilicate to 200 mL of the first mixture and mix at 40 °C for 8 h to obtain the second mixture, wherein the weight ratio of the first mixture to tetraethyl orthosilicate is 100:15.

[0084] (3) The second mixture was transferred to a stainless steel reactor with a polytetrafluoroethylene liner and subjected to a hydrothermal reaction at 140°C for 2 days to obtain the hydrothermal reaction product. The hydrothermal reaction product was cooled and removed and filtered. The solid product was washed with water and dried at 120°C for 2 hours. Then, it was calcined at 280°C for 10 hours in a carbon dioxide atmosphere. Finally, it was calcined at 700°C for 1 hour in an air atmosphere to obtain nanomaterial B.

[0085] (4) Collect the liquid phase product after solid-liquid separation and contact it with NaY molecular sieve (pore size of 0.74nm) at room temperature for 3h. The mass ratio of liquid phase product to NaY molecular sieve is 25:1. The COD of the clear liquid after contact is less than 50ppm and can be directly discharged.

[0086] (5) After contacting the NaY molecular sieve, dry it at 150°C for 6 hours and then calcine it at 600°C for 4 hours in air atmosphere to obtain the calcined NaY molecular sieve for later use.

[0087] Example 3

[0088] (1) Add 1000 mL of ethylenediamine aqueous solution to a beaker, place the anode graphite rod (8 mm in diameter and 50 cm in length) and the cathode graphite rod (8 mm in diameter and 50 cm in length) in it, keep the distance between the anode graphite rod and the cathode rod at 5 cm, connect the anode graphite rod to the positive terminal of the DC power supply and connect the cathode rod to the negative terminal of the DC power supply, electrolyze at 20 V for 2 days to obtain a first mixture containing organic base and carbon dots; the concentration of carbon dots in the first mixture is 10 mg / L and the concentration of ethylenediamine is 300 mmol / L;

[0089] (2) Add tetraethyl orthosilicate to 100 mL of the first mixture and mix at 60 °C for 4 h to obtain the second mixture, wherein the weight ratio of the first mixture to tetraethyl orthosilicate is 100:25.

[0090] (3) The second mixture was transferred to a stainless steel reactor with a polytetrafluoroethylene liner and subjected to a hydrothermal reaction at 140°C for 3 days to obtain the hydrothermal reaction product. The hydrothermal reaction product was cooled and removed, filtered, and the solid product was washed with water and dried at 110°C for 2 hours. It was then calcined for 10 hours at 280°C in an argon atmosphere and then calcined for 1 hour at 700°C in an air atmosphere to obtain nanomaterial C.

[0091] (4) Collect the liquid phase product after solid-liquid separation, and contact it with the β molecular sieve (pore size of 0.7 nm) after calcination in Example 1 at room temperature for 3 hours. The mass ratio of the liquid phase product to the β molecular sieve is 100:1. The COD of the clear liquid after contact is less than 50 ppm, and it can be directly discharged.

[0092] (5) After contacting the β molecular sieve, dry it at 120°C for 6 hours and then calcine it at 500°C for 2 hours in air atmosphere to obtain the calcined β molecular sieve for later use.

[0093] Example 4

[0094] (1) Add 5000 mL of tetraethylammonium hydroxide aqueous solution to a beaker, place the anode graphite rod (8 mm in diameter and 50 cm in length) and the cathode graphite rod (8 mm in diameter and 50 cm in length) in it, keep the distance between the anode graphite rod and the cathode rod at 5 cm, connect the anode graphite rod to the positive terminal of the DC power supply and connect the cathode rod to the negative terminal of the DC power supply, electrolyze at 15 V for 4 days to obtain a first mixture containing organic base and carbon dots; the concentration of carbon dots in the first mixture is 65 mg / L and the concentration of tetraethylammonium hydroxide is 1500 mmol / L;

[0095] (2) Add tetraethyl orthosilicate to 40 mL of the first mixture and mix at 30 °C for 12 h to obtain the second mixture, wherein the weight ratio of the first mixture to tetraethyl orthosilicate is 100:40.

[0096] (3) The second mixture was transferred to a stainless steel reactor with a polytetrafluoroethylene liner and subjected to a hydrothermal reaction at 140°C for 4 days to obtain the hydrothermal reaction product. The hydrothermal reaction product was cooled and removed and filtered. The solid product was washed with water and dried at 110°C for 2 hours. It was then calcined for 10 hours at 280°C in a carbon dioxide atmosphere. Finally, it was calcined for 1 hour at 700°C in an air atmosphere to obtain nanomaterial D.

[0097] (4) Collect the liquid phase product after solid-liquid separation and contact it with mesoporous MCM-41 molecular sieve (pore size of 3nm) at room temperature for 12h. The mass ratio of liquid phase product to mesoporous molecular sieve is 500:1. The COD of the clear liquid after contact is less than 50ppm and can be directly discharged.

[0098] (5) After contact, the mesoporous MCM-41 molecular sieve is dried at 110℃ for 2 hours and then calcined at 400℃ for 1 hour in air atmosphere to obtain the calcined mesoporous MCM-41 molecular sieve for use.

[0099] Example 5

[0100] Nanomaterial E was prepared using the same method as in Example 1, except that in step (2), an appropriate amount of tetraethyl orthosilicate was mixed and added to 100 mL of the first mixture. The weight ratio of the first mixture to tetraethyl orthosilicate was 100:2, resulting in the second mixture. The COD of the clear liquid after contact in step (4) was less than 50 ppm, and it could be directly discharged.

[0101] Example 6

[0102] Nanomaterial F was prepared using the same method as in Example 1, except that in step (3), calcination was performed only once. Specifically, in step (3), the second mixture was transferred to a stainless steel reactor and subjected to a hydrothermal reaction at 170°C for 72 hours to obtain the hydrothermal reaction product. After cooling and removing the hydrothermal reaction product, it was filtered. The solid product was washed with water and dried at 110°C for 3 hours. Then, it was directly calcined in air at 700°C for 1 hour to obtain nanomaterial F. The COD of the clear liquid after contact in step (4) was less than 50 ppm, and it could be directly discharged.

[0103] Comparative Example 1

[0104] Nanomaterial a was prepared using the same method as in Example 1, except that:

[0105] In step (1), tetrapropylammonium hydroxide is not added; the concentration of carbon points in the first mixture is 0.2 mg / L;

[0106] In step (2), 25g of tetraethyl orthosilicate is mixed with 100mL of the first mixture and 10g of tetrapropylammonium hydroxide to obtain the second mixture.

[0107] Comparative Example 2

[0108] Nanomaterial b was prepared using the same method as in Example 1, except that in step (1), an equal mass of sodium hydroxide was used to replace tetrapropylammonium hydroxide to obtain a first mixture containing an inorganic base and carbon dots.

[0109] Comparative Example 3

[0110] Nanomaterial c was prepared using the same method as in Example 1, except that in step (4), an equal mass of SPO4-34 (pore size of 0.4 nm) was used to replace the β molecular sieve. The COD of the clear liquid after contact reached 460 ppm, and it could not be discharged directly.

[0111] Comparative Example 4

[0112] (1) Add tetrapropylammonium hydroxide and distilled water to a 1000mL beaker to form a 500mL aqueous solution of organic base as the electrolyte. Place the anode graphite rod (8mm in diameter and 30cm in length) and the cathode graphite rod (8mm in diameter and 30cm in length) in the solution, keeping the distance between the anode graphite rod and the cathode rod at 10cm. Connect the anode graphite rod to the positive terminal of the DC power supply and the cathode rod to the negative terminal of the DC power supply. Apply a voltage of 65V and electrolyze for 3 days to obtain a carbon point solution. The concentration of the carbon point solution is 160mg / L, and the content of tetrapropylammonium hydroxide in the aqueous solution of organic base is 150mmol / L.

[0113] (2) First, mix 25g of tetraethyl orthosilicate and 5g of glycerol evenly, then add 60mL of the carbon dot solution obtained in step (1) and mix evenly. Stir at 75°C for 3 hours to obtain a mixture; wherein, the weight ratio of silicon source (tetraethyl orthosilicate), glycerol and carbon dot solution is 100:20:240.

[0114] (3) The mixture was placed in a stainless steel reactor with a polytetrafluoroethylene liner and kept at a constant temperature of 170°C for 3 days. The solid of the hydrothermal reaction was obtained by filtration. The solid was washed with deionized water, dried at 110°C for 1 hour, and calcined in air at 550°C for 3 hours to obtain nanoporous material d.

[0115] Test Example 1

[0116] This test case illustrates the effectiveness of the nanomaterials prepared in the examples and comparative examples for catalyzing the cyclohexanone oxime rearrangement reaction at a reaction temperature of 310°C.

[0117] Two ounces of the nanomaterials synthesized in the above examples and comparative examples were sequentially placed into the isothermal section of a fixed-bed reactor as catalysts. Under normal pressure, cyclohexanone oxime was introduced into the reactor at a weight ratio of 1:25 to methanol (solvent), with a feed rate of 100 g / h and a reaction temperature of 310 °C. The reaction was carried out at this temperature for 6 hours. The oxidation products were analyzed by gas chromatography (GC: Agilent, 7890A) and gas chromatography-mass spectrometry (GC-MS: Thermo Fisher Trace ISQ). The results are shown in Table 1.

[0118] The following formulas are used to calculate the feed conversion rate and target product selectivity:

[0119] Cyclohexanone oxime conversion rate = (amount of cyclohexanone oxime added before reaction - amount of cyclohexanone oxime remaining after reaction) / amount of cyclohexanone oxime added before reaction × 100%;

[0120] Caprolactam selectivity = Amount of caprolactam generated after the reaction / (Amount of cyclohexanone oxime added before the reaction - Amount of cyclohexanone oxime remaining after the reaction) × 100%.

[0121] Test Example 2

[0122] This test example illustrates the effectiveness of the nanomaterials prepared in the examples and comparative examples in catalyzing the cyclohexanone oxime rearrangement reaction at a reaction temperature of 350°C. Other reaction conditions and result analysis are the same as in Test Example 1, and the results are shown in Table 1.

[0123] Table 1

[0124]

[0125] As shown in Table 1, the nanomaterials prepared by the method disclosed in this paper have superior catalytic activity. The reaction for preparing amides from oxime rearrangements can achieve high oxime conversion and amide selectivity at relatively low temperatures.

[0126] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0127] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0128] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. The application of nanomaterials in the preparation of amides from oxime rearrangements, characterized in that, The method for preparing the nanomaterial includes: (1) Electrolyze the graphite molded body in an electrolyte containing 1-8 carbon atoms of the longest chain to obtain a first mixture containing carbon dots and organic base; the size of the carbon dots is 3-6 nm; (2) The silicon source is mixed with the first mixture to obtain a second mixture; (3) The second mixture is subjected to a hydrothermal reaction in a heat-resistant sealed container; (4) After cooling the reaction product obtained by hydrothermal treatment, solid-liquid separation is performed to obtain solid product and liquid product. The solid product is subjected to a first heat treatment to obtain nanomaterials. (5) The liquid phase product is brought into contact with a porous material, wherein the pore size of the porous material is greater than 0.7 nm; (6) Perform a second heat treatment on the porous material after contact; In step (3), the conditions for the hydrothermal reaction include: a temperature of 100-200℃ and a time of 6-144h; In step (4), the first heat treatment of the solid product includes: sequentially subjecting the solid product to a first calcination and a second calcination; The conditions for the first calcination include: 200-500℃, time of 2-24h, and an inert atmosphere; The conditions for the second roasting include: 400-800℃, time of 1-12h, and air atmosphere.

2. The application according to claim 1, wherein, In step (1), the electrolysis voltage is 15-45V and the time is 1-10 days.

3. The application according to claim 1, wherein, In the first mixture, the carbon point content is 5-1000 mg / L, and the concentration of the organic base is 50-2000 mmol / L.

4. The application according to claim 1, wherein, In step (2), the weight ratio of the first mixture to the amount of silicon source is 100:(1-80).

5. The application according to claim 1, wherein, In step (5), the weight ratio of the liquid phase product to the porous material is 1000:(1-500).

6. The application according to claim 1, wherein, The contact conditions include: a time of 5-720 min and a temperature of 20-100℃.

7. The application according to claim 1, wherein, The porous material is selected from one or more of MOR molecular sieves, Y molecular sieves, β molecular sieves, mesoporous molecular sieves, carbon nanotubes, and activated carbon.

8. The application according to claim 1, wherein, In step (6), the conditions for the second heat treatment include: a time of 1-8 hours, a temperature of 500-800°C, and an air atmosphere.

9. The application according to claim 1, wherein, The organic base with the longest chain having 1-8 carbon atoms is selected from one or more of urea, quaternary ammonium bases with the longest chain having 1-8 carbon atoms, aliphatic amines with 1-6 carbon atoms, and alcohol amines with 1-6 carbon atoms. The silicon source is an organosilicon source and / or an inorganic silicon source.

10. The application according to claim 9, wherein, The quaternary ammonium base compound with the longest chain having 1-8 carbon atoms is tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, or a combination of two or three of them.

11. The application according to claim 9, wherein, The aliphatic amine compounds having 1-6 carbon atoms are ethylamine, ethylenediamine, n-butylamine, butylenediamine, or hexamethylenediamine, or a combination of two or three of them.

12. The application according to claim 9, wherein, The alkanolamines having 1-6 carbon atoms are monoethanolamine, diethanolamine, or triethanolamine, or a combination of two or three of them.

13. The application according to claim 9, wherein, The organosilicon source is selected from tetramethyl silicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, or dimethoxydiethoxysilane, or a combination of two or three of them.

14. The application according to claim 9, wherein, The inorganic silicon source is silica sol and / or silica gel.

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