CN111606798A

CN111606798A - Process for the catalytic oxidation of cyclic ketones

Info

Publication number: CN111606798A
Application number: CN201910142915.9A
Authority: CN
Inventors: 史春风; 康振辉; 刘阳; 黄慧; 王肖; 蔺晓玲; 赵娟
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Petrochemical Research Institute Co ltd; Sinopec Research Institute (Tianjin) Technology Development Co.,Ltd.; China Petroleum and Chemical Corp
Priority date: 2019-02-26
Filing date: 2019-02-26
Publication date: 2020-09-01
Anticipated expiration: 2039-02-26
Also published as: CN111606798B

Abstract

The present disclosure relates to a process for the catalytic oxidation of a cyclic ketone, the process comprising: the cyclic ketone and the peroxide are contacted to react in the presence of a catalyst, wherein the catalyst is a catalytic composite material containing carbon points and titanium oxide. The method adopts the catalytic composite material containing carbon dots and titanium oxide as the catalyst to catalyze the oxidation reaction of the cyclic ketone, can realize the oxidation of the cyclic ketone under mild conditions, has higher raw material conversion rate and higher selectivity of a target product, namely dicarboxylic acid, and can obviously improve the effective utilization rate of peroxide and reduce the production cost.

Description

Process for the catalytic oxidation of cyclic ketones

Technical Field

The present disclosure relates to a process for the catalytic oxidation of cyclic ketones.

Background

Carbon-based materials include carbon nanotubes, activated carbon, graphite, graphene, fullerenes, carbon nanofibers, nanodiamonds, and the like. Scientific research on nanocarbon catalysis began in the last 90 s of the century. Researches show that the surface chemical properties of the nano-carbon material (mainly carbon nano-tubes and graphene) can be flexibly regulated, and saturated and unsaturated functional groups containing heteroatoms such as oxygen, nitrogen and the like can be modified on the surface of the nano-carbon material, so that the nano-carbon material has certain acid-base properties and redox capability, and can be directly used as a catalyst material. Research and development of new catalytic materials related to fullerene (carbon nano tube) and broadening of the application of the new catalytic materials in the fields of petrochemical industry, fine chemical industry and the like have profound theoretical significance and huge potential application prospects.

Dicarboxylic acids are an important class of organic chemical products, for example, adipic acid is an important organic compound, is a colorless and transparent solid at normal temperature, and is dissolved in water, ethanol, acetone, diethyl ether and chloroform. Adipic acid is generally produced by the oxidation of cyclohexanone, and generally includes the nitric acid oxidation, the peroxide oxidation, the ozone oxidation, the anodic oxidation and the nitrogen dioxide oxidation, depending on the oxidizing agent and the oxidation method used. The peroxide oxidation method has the advantages of mild reaction conditions, simple equipment and process route, no need of alkali for neutralization of the product, and no pollution to the environment. However, in the peroxide oxidation method, the oxidizing agent is expensive and used in a large amount, which increases the production cost of adipic acid and limits the application range of the peroxide oxidation method. Therefore, when the cyclohexanone is oxidized by the peroxide oxidation method, it is an important subject to improve the effective utilization rate of the oxidizing agent and to reduce the production cost of adipic acid.

Disclosure of Invention

The purpose of the disclosure is to provide a catalytic oxidation method of cyclic ketone, which can not only obtain higher raw material conversion rate and selectivity of target product dicarboxylic acid, but also obtain higher effective utilization rate of peroxide.

In order to achieve the above object, the present disclosure provides a method for catalytic oxidation of cyclic ketones, the method comprising: the cyclic ketone and the peroxide are contacted to react in the presence of a catalyst, wherein the catalyst is a catalytic composite material containing carbon dots and titanium oxide, and the content of the carbon dots is 2-40 wt% and the content of the titanium oxide is 60-98 wt% based on the total weight of the catalytic composite material.

Optionally, based on the total weight of the catalytic composite material, the content of the carbon dots is 5-20 wt%, and the content of the titanium oxide is 80-95 wt%.

Optionally, the carbon dots are graphene quantum dots, carbon nanodots, or polymer dots.

Optionally, the particle size of the catalytic composite material is 10-5000 nm, and preferably 10-1000 nm.

Optionally, the step of preparing the catalytic composite comprises:

(1) mixing a first solution containing a titanium source and a first solvent with a second solution containing an acid and a second solvent under stirring to obtain a mixed solution;

(2) and (2) mixing the mixed solution obtained in the step (1) with a third solution containing carbon points, carrying out hydrothermal reaction for 0.5-48 h at 100-400 ℃, collecting a solid product, and then drying and roasting.

Optionally, in step (1), the molar ratio of the titanium source, the first solvent, the second solvent, and the acid is 1: (0.1-100): (0.1-50): (0.1 to 10); and/or the presence of a gas in the gas,

the titanium source is tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, tetramethyl titanate, titanyl sulfate or titanyl chloride, or a combination of two or three of the above; and/or the presence of a gas in the gas,

the acid is acetic acid, propionic acid, hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, or a combination of two or three of the above; and/or the presence of a gas in the gas,

the first solvent is ethanol, n-propanol, isopropanol, n-butanol, tert-butanol or cyclohexanol, or a combination of two or three of the above; and/or the presence of a gas in the gas,

the second solvent is water, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol or cyclohexanol, or a combination of two or three of them.

Optionally, the step of preparing the catalytic composite further comprises: in the step (1), adding the first solution into the second solution at a speed of 0.1-50 mL/min; and/or the presence of a gas in the gas,

the stirring conditions include: the stirring speed is 100-2000 rpm, preferably 200-1000 rpm, and the time is 0.1-12 h, preferably 0.5-6 h.

Optionally, in the step (2), the weight ratio of the third solution to the mixed solution is (0.01-10): 1, preferably (0.1 to 0.8): 1; and/or the presence of a gas in the gas,

the drying conditions include: the temperature is 100-200 ℃, and the time is 1-12 h; and/or the presence of a gas in the gas,

the roasting conditions comprise: the temperature is 250-800 ℃, and the time is 0.5-6 h.

Optionally, the reaction is carried out in a slurry bed reactor, and the amount of the catalyst is 10-100 mg, preferably 20-60 mg, based on 10mL of the cyclic ketone; or,

the reaction is carried out in a fixed bed reactor, and the weight hourly space velocity of the cyclic ketone is 0.01-500 h^-1Preferably 0.05 to 2 hours^-1(ii) a Or,

the reaction is carried out in a microchannel reactor, and the dosage of the catalyst is 0.2-50 mg, preferably 0.5-20 mg, based on 10mL of the cyclic ketone; the residence time of the reaction materials is 0.1-15 min, preferably 0.5-10 min.

Optionally, the method further comprises: the reaction is carried out in the presence of a third solvent; the third solvent is water, C1-C6 alcohol or C2-C6 nitrile, or a combination of two or three thereof; and/or the presence of a gas in the gas,

the weight ratio of the cyclic ketone to the third solvent is 1: (0.1 to 20).

Optionally, the peroxide is hydrogen peroxide, cumene peroxide, cyclohexyl hydroperoxide, or tert-butyl hydroperoxide, or a combination of two or three thereof; and/or the presence of a gas in the gas,

the molar ratio of the cyclic ketone to the peroxide is 1: (1 to 10), preferably 1: (2-5).

Optionally, the cyclic ketone is cyclohexanone, cyclopentanone, methylcyclopentanone, or methylcyclohexanone.

Optionally, the reaction conditions are: the temperature is 0-100 ℃, and preferably 20-80 ℃; the pressure is 0 to 3MPa, preferably 0.1 to 2.5 MPa.

According to the technical scheme, the catalytic composite material containing carbon dots and titanium oxide is used as the catalyst to catalyze the oxidation reaction of the cyclic ketone, the oxidation of the cyclic ketone can be realized under mild conditions, the conversion rate of raw materials and the selectivity of a target product, namely dicarboxylic acid are high, the effective utilization rate of peroxide can be obviously improved, and the production cost is reduced.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Detailed Description

The following describes in detail specific embodiments of the present disclosure. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

The present disclosure provides a process for the catalytic oxidation of a cyclic ketone, the process comprising: the cyclic ketone and the oxidant are contacted to react in the presence of a catalyst, wherein the catalyst is a catalytic composite material containing carbon points and titanium oxide.

According to the present disclosure, the content of the carbon dots is 2 to 40 wt% and the content of the titanium oxide is 60 to 98 wt%, based on the total weight of the catalytic composite material. The catalytic composite material can realize the oxidation of cyclic ketone under a mild condition, has high raw material conversion rate and high target product selectivity, and can obviously improve the effective utilization rate of peroxide. In order to better achieve the object of the present disclosure, it is preferable that the content of the carbon dots is 5 to 20 wt% and the content of the titanium oxide is 80 to 95 wt% based on the total weight of the catalytic composite.

According to the present disclosure, the Carbon Dots (CDs) refer to carbon particles having fluorescent properties with a size of less than 20 nm. The chemical structure of the carbon dots may be sp²And sp³The hybrid carbon structure of (3) has a single-layer or multi-layer graphite structure, and may be polymer-based aggregated particles. The carbon dots mainly comprise graphene quantum dots, carbon nanodots and polymer dots. The graphene quantum dots refer to a carbon core structure with a single layer or less than 5 layers of graphene and chemical groups bonded at edges. The size of the graphene quantum dots has a typical anisotropy, the transverse dimension is larger than the height of the longitudinal direction, and the graphene quantum dots have a typical carbon lattice structure. Graphene quantum dots are a class of materials that physicists use to study the photoelectric band gap of graphene, and typically require electron beam etching of large sheets of graphene. The carbon nanodots are generally spherical structures, and may be classified into lattice-distinct carbon nanodots and lattice-free carbon nanodots. Due to the diversity of the carbon nano-dot structure, the carbon nano-dot luminescent centers prepared in different modes and the luminescent mechanism have great difference. Specifically, it can be classified into carbon quantum dots having distinct lattices and carbon nanodots having/not having lattices. The carbon quantum dots with obvious crystal lattices have obvious quantum size dependence, and the optimal fluorescence emission peak is red-shifted along with the size increase. The lattice-free carbon nano-dots have no quantum size effect, the luminescent centers of the lattice-free carbon nano-dots are not completely controlled by the carbon cores, and the surface groups have non-negligible influence on luminescence. The polymer dots are typically cross-linked flexible aggregates formed from non-conjugated polymers by dehydration or partial carbonization, with no carbon lattice structure present. Polymer dots are a class of materials from which carbon dots extend. The polymer dots comprise fluorescent polymer dots formed by moderately crosslinking or carbonizing non-conjugated macromolecules and fluorescent polymer dots formed by assembling carbon cores and polymers.

Methods for preparing the carbon dots are well known to those skilled in the art in light of this disclosure. The raw material source of the carbon dots may generally include both inorganic carbon sources and organic carbon sources. The specific preparation method can comprise methods such as an arc discharge method, a laser ablation/passivation method, an electrochemical method, a pyrolysis method, a field-assisted method and the like. The carbon dots can be prepared in one step by a high temperature pyrolysis method, usually using citrate as a carbon source or using citric acid and glutathione together as a carbon source.

According to the present disclosure, the carbon dots are preferably graphene quantum dots, carbon nanodots or polymer dots, and the carbon dots are commercially available or can be prepared by methods known in the art. The particle size of the carbon dots is generally 3-20 nm.

According to the present disclosure, the titanium oxide (TiO)₂) The particle size of (A) may be 10 to 5000 nm.

According to the present disclosure, the particle size of the catalytic composite material may be 10 to 5000nm, preferably 10 to 1000 nm. In the present disclosure, the particle size refers to the maximum three-dimensional length of the particle, i.e., the maximum distance between two points on the particle.

In accordance with the present disclosure, the objects of the present disclosure are achieved with a catalytic composite having the above-described features. In a preferred embodiment, the step of preparing the catalytic composite may comprise:

According to the present disclosure, in step (1), the molar ratio of the titanium source, the first solvent, the second solvent, and the acid may be 1: (0.1-100): (0.1-50): (0.1 to 10), preferably 1: (1-50): (1-25): (0.2-5). The titanium source is a compound containing titanium, and may be, for example, tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, tetramethyl titanate, titanyl sulfate or titanyl chloride, or a combination of two or three of them. The acid may be a common organic or inorganic acid, and may be, for example, acetic acid, propionic acid, hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, or a combination of two or three thereof. The first solvent may be ethanol, n-propanol, isopropanol, n-butanol, tert-butanol or cyclohexanol, or a combination of two or three thereof; the second solvent may be water, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol or cyclohexanol, or a combination of two or three thereof; the first solvent and the second solvent may be the same or different in kind. The pH value of the second solution can be 0-6.

According to the present disclosure, in order to make the mixing of the first solution and the second solution more sufficient, the preparing step of the catalytic composite material may further include: in the step (1), the first solution is added into the second solution at a speed of 0.1-50 mL/min. The mixing is performed under agitation conditions, which may include: the stirring speed is 100-2000 rpm, preferably 200-1000 rpm, and the time is 0.1-12 h, preferably 0.5-6 h.

According to the disclosure, in the step (2), the third solution is used in an amount such that the content of the carbon dots in the prepared catalytic composite material is 2 to 40 wt%, and the content of the titanium oxide in the prepared catalytic composite material is 60 to 98 wt%, based on the total weight of the catalytic composite material. For example, the weight ratio of the third solution to the mixed solution may be (0.01 to 10): 1, preferably (0.1 to 0.8): 1. the hydrothermal reaction may be carried out in a conventional reactor, for example in a polytetrafluoroethylene reactor. The pressure of the hydrothermal reaction process is not particularly limited, and may be the autogenous pressure of the system, or may be under an additional applied pressure condition, and preferably, the hydrothermal reaction process is performed under the autogenous pressure (generally, in a closed vessel). The method of collecting the solid product after the hydrothermal reaction may be carried out by a conventional method such as filtration, centrifugation and the like. The conditions for drying and calcining the solid product may be conventional in the art, for example, the drying conditions may include: the temperature is 100-200 ℃, and the time is 1-12 h; the conditions for the firing may include: the temperature is 250-800 ℃, and the time is 0.5-6 h.

The process for the catalytic oxidation of cyclic ketones of the present disclosure can be carried out in various conventional catalytic reactors, for example, can be carried out in a batch tank reactor or a three-neck flask, or in suitable other reactors such as fixed bed, moving bed, suspended bed, and the like.

In an alternative embodiment of the present disclosure, the reaction is carried out in a slurry bed reactor. In this case, the amount of the catalyst may be appropriately selected according to the amounts of the cyclic ketone and the peroxide, and for example, the amount of the catalyst may be 10 to 100mg, preferably 20 to 60mg, based on 10mL of the cyclic ketone.

In another alternative embodiment of the present disclosure, the reaction may be carried out in a fixed bed reactor. At this time, the weight hourly space velocity of the cyclic ketone can be 0.01-500 h^-1Preferably 0.05 to 2 hours^-1。

In a preferred embodiment of the present disclosure, the reaction is carried out in a microchannel reactor. In this case, the amount of the catalyst may be 0.2 to 50mg, preferably 0.5 to 20mg, based on 10mL of the cyclic ketone; the residence time of the reaction materials can be 0.1-15 min, preferably 0.5-10 min; wherein the reaction material refers to a mixture of materials which comprise cyclic ketone, peroxide, catalyst and the like and enter the microchannel reactor to participate in the reaction.

According to the present disclosure, to increase the degree of mixing between the reaction materials, the method may further comprise: the reaction is carried out in the presence of a third solvent. The third solvent may be various liquid substances capable of dissolving the cyclic ketone and the peroxide or promoting the mixing of the two and promoting the dissolution of the target product. Generally, the third solvent may be water, an alcohol of C1-C6, a ketone of C3-C8, or a nitrile of C2-C6, or a combination of two or three thereof. Specific examples of the third solvent may include, but are not limited to: water, methanol, ethanol, n-propanol, isopropanol, cyclohexanone, isobutanol, acetone, butanone, and acetonitrile. Preferably, the third solvent is selected from water and C1-C6 alcohols. More preferably, the third solvent is methanol and/or water. The amount of the third solvent may be appropriately selected according to the amounts of the cyclic ketone and the peroxide, and for example, the weight ratio of the cyclic ketone to the third solvent may be 1: (0.1 to 20), preferably 1: (1-10).

According to the present disclosure, the peroxide refers to a compound having an-O-bond in the molecular structure, and may be selected from hydrogen peroxide, hydroperoxides and peracids. The hydroperoxide is a substance obtained by substituting one hydrogen atom in a hydrogen peroxide molecule with an organic group. The peracid refers to an organic oxyacid having an-O-O-bond in the molecular structure. Specific examples of the peroxide may include, but are not limited to, hydrogen peroxide, cumene peroxide, cyclohexyl hydroperoxide, or tert-butyl hydroperoxide. Preferably, the peroxide is hydrogen peroxide, which may be in various forms commonly used in the art. From the viewpoint of further improving the safety of the method according to the present disclosure, it is preferable to use hydrogen peroxide in the form of an aqueous solution, and in this case, the concentration of the aqueous hydrogen peroxide may be a concentration conventional in the art, for example, 20 to 80 wt%. The aqueous solution of hydrogen peroxide having a concentration satisfying the above requirements may be prepared by a conventional method or may be commercially available, for example, 30 wt% hydrogen peroxide.

According to the present disclosure, the molar ratio of the cyclic ketone to the peroxide may be 1: (1 to 10), preferably 1: (2-5).

According to the present disclosure, the cyclic ketone may be cyclohexanone, cyclopentanone, methylcyclopentanone, or methylcyclohexanone, preferably cyclohexanone.

According to the present disclosure, the conditions of the reaction may be: the temperature is 0-100 ℃, and preferably 20-80 ℃; the pressure is 0 to 3MPa, preferably 0.1 to 2.5 MPa. In order to make the reaction more sufficient, it is preferable that the reaction is carried out under stirring.

The method takes the catalytic composite material containing carbon dots and titanium oxide as the catalyst to catalyze the oxidation reaction of the cyclic ketone, can realize the oxidation of the cyclic ketone under mild conditions, has high raw material conversion rate and high target product selectivity, and can obviously improve the effective utilization rate of peroxide and reduce the production cost.

The present disclosure is described in detail below with reference to examples, but the scope of the present disclosure is not limited thereby.

Preparation examples 1-5 are provided to illustrate the preparation of the catalytic composite employed in the present disclosure.

In the following preparation examples, solutions containing carbon dots having a particle size of 9nm and a concentration of 0.01 wt% were purchased from Suzhou university. Titanium oxide was purchased from winning companies and had a particle size of 300 nm. The particle size of the composite material was determined by TEM, and 20 particles were randomly selected from the TEM photograph, and the average size thereof was calculated. The method for measuring the content of the carbon points and the titanium oxide in the catalytic composite material is a roasting method, the catalytic composite material is roasted for 2 hours at the temperature of 400 ℃, the percentage of the residual weight to the weight before roasting is the content of the titanium oxide, and the percentage of the lost weight to the weight before roasting is the content of the carbon points.

Preparation of example 1

Tetrabutyl titanate and the first solvent absolute ethyl alcohol are vigorously stirred for 10min (the stirring speed is 800 revolutions per minute) to obtain a first solution. The glacial acetic acid, the second solvent water and the absolute ethyl alcohol are stirred vigorously (the stirring speed is 800 r/min), and hydrochloric acid is added to ensure that the pH value is less than 3, so as to obtain a second solution. Adding the first solution into the second solution at a speed of 3mL/min under the condition of vigorous stirring at a stirring speed of 800 revolutions per minute in a room-temperature water bath to form a light yellow mixed solution, wherein the molar ratio of tetrabutyl titanate to the first solvent to the second solvent to the acid is 1: 10: 5: 1. and (3) mixing the third solution containing the carbon dots with the mixed solution according to the weight ratio of 0.25: 1, mixing, stirring for 0.5h, transferring into a hydrothermal kettle, carrying out hydrothermal reaction for 6h at 80 ℃, collecting a solid product, drying at 105 ℃, and roasting at 500 ℃ to obtain CDs/TiO₂Catalytic composite A1, particle average size about 150nm, CDs content 8 wt%, TiO₂The content was 92% by weight.

Preparation of example 2

A composite material was prepared by the method of preparation example 1, except that, during the synthesis, the weight ratio of the third solution containing carbon dots to the mixed solution of the first solution and the second solutionIs 0.5: 1, obtaining CDs/TiO₂Composite particles A2 having an average particle size of about 65nm, a CDs content of 15 wt%, TiO₂The content was 85% by weight.

Preparation of example 3

A composite material was prepared according to the method of preparation example 1, except that, during the synthesis, the molar ratio of tetrabutyl titanate, the first solvent, the second solvent and the acid was 1: 60: 30: 10, obtaining CDs/TiO₂Composite particles A3 having an average particle size of about 1100nm and a CDs content of 9 wt%, TiO₂The content was 91% by weight.

Preparation of example 4

A composite material was prepared according to the method of preparation example 1, except that, during the synthesis, the weight ratio of the third solution containing carbon dots to the mixed solution of the first solution and the second solution was 1: 1, obtaining CDs/TiO₂Composite particles A4 having an average particle size of about 30nm, a CDs content of 33 wt%, TiO₂The content was 67% by weight.

Preparation of example 5

A composite material was prepared according to the method of preparation example 1, except that, during the synthesis, the weight ratio of the third solution containing carbon dots to the mixed solution of the first solution and the second solution was 0.05: 1, obtaining CDs/TiO₂Composite particles A5 having an average particle size of about 420nm and a CDs content of 4% by weight, TiO₂The content was 96% by weight.

Examples 1-13 are provided to illustrate the process of the present disclosure for the catalytic oxidation of cyclic ketones.

In the following examples and comparative examples, the oxidation products were analyzed by gas chromatography (GC: Agilent, 7890A) and gas chromatography-mass spectrometer (GC-MS: Thermo Fisher Trace ISQ). Conditions of gas chromatography: nitrogen carrier gas, temperature programmed at 140K: 60 ℃, 1 minute, 15 ℃/minute, 180 ℃, 15 minutes; split ratio, 10: 1; the injection port temperature is 300 ℃; detector temperature, 300 ℃. On the basis, the conversion rate of raw materials and the selectivity of target products are calculated by respectively adopting the following formulas:

percent cyclic ketone conversion ═ molar amount of cyclic ketone added before reaction-molar amount of cyclic ketone remaining after reaction)/molar amount of cyclic ketone added before reaction × 100%;

target product selectivity ═ molar amount of target product formed after the reaction)/molar amount of cyclic ketone added before the reaction × 100%.

The peroxide effective utilization ratio%.

Example 1

Cyclohexanone, 30 wt% hydrogen peroxide and methanol as solvent were mixed and composite particles a1 as catalyst were added to form a reaction mass. The reaction mass was then fed into the reaction zone from the feed inlet of a microchannel reactor (model HR-50, corning, usa) in which the molar ratio of cyclohexanone to hydrogen peroxide was 1: 4, the weight ratio of cyclohexanone to methanol is 1: 4; taking 10mL of cyclohexanone as a reference, the using amount of the composite material particles A1 is 5mg, the reaction temperature is 30 ℃, the pressure is 0.8MPa, the residence time of reaction materials is 2min, collecting a reaction mixture at a discharge hole, carrying out gas chromatography analysis, and calculating the conversion rate of the cyclohexanone, the effective utilization rate of peroxide and the selectivity of a target product, namely adipic acid. The results are listed in table 1.

Examples 2 to 5

Cyclohexanone was catalytically oxidized according to the method of example 1, except that the A1 was replaced with the same amount of composite particles A2 to A5, respectively. The results of the oxidation product analysis are shown in Table 1.

Example 6

Cyclohexanone was catalytically oxidized according to the method of example 1, except that the molar ratio of cyclohexanone to hydrogen peroxide was 1: 6, the weight ratio of cyclohexanone to methanol is 1: 20; the amount of composite particles A1 was 25mg based on 10mL cyclohexanone. The results of the oxidation product analysis are shown in Table 1.

Example 7

Cyclohexanone was catalytically oxidized according to the method of example 1, except that the molar ratio of cyclohexanone to hydrogen peroxide was 1: 1, the weight ratio of cyclohexanone to methanol is 1: 0.8; the amount of composite particles A1 was 0.2mg based on 10mL of cyclohexanone. The results of the oxidation product analysis are shown in Table 1.

Example 8

Cyclohexanone, 30 wt% hydrogen peroxide and methanol as solvent were mixed to form a liquid mixture. Then, the liquid mixture was fed from the feed inlet at the bottom of the conventional fixed bed reactor into a reaction zone to contact with composite particles a1 as a catalyst, wherein the molar ratio of cyclohexanone to hydrogen peroxide was 1: 4, the weight ratio of cyclohexanone to methanol is 1: 4; the reaction temperature is 30 ℃, the pressure is 0.8MPa, and the weight hourly space velocity of the cyclohexanone is 2.0h^-1. The reaction mixture obtained after the reaction was carried out for 2 hours was subjected to gas chromatography, and the results are shown in Table 1.

Example 9

60mg of composite particles A1 as a catalyst and 10mL of cyclohexanone were added to a 250mL autoclave, then 30 wt% hydrogen peroxide and methanol as a solvent were added, the molar ratio of cyclohexanone to hydrogen peroxide was 1: 4, the weight ratio of cyclohexanone to methanol is 1: 4; after stirring and reacting for 2h at 30 ℃ and 0.8MPa, the temperature is reduced, the pressure is relieved, the sample is taken, the catalyst is separated by centrifugation and filtration, and the results of analyzing the oxidation products are shown in Table 1.

Example 10

Cyclohexanone was catalytically oxidized according to the method of example 9, except that the amount of composite particles A1 was 10 mg. The results of the oxidation product analysis are shown in Table 1.

Example 11

Cyclohexanone was catalytically oxidized according to the method of example 9, except that the amount of composite particles A1 was 85 mg. The results of the oxidation product analysis are shown in Table 1.

Example 12

Cyclohexanone was catalytically oxidized according to the procedure of example 1, except that methanol was not added as a solvent. The results of the oxidation product analysis are shown in Table 1.

Example 13

Methylcyclopentanone, 30 wt% hydrogen peroxide and tert-butanol as solvent were mixed, and modified graphite nanopowder C1 as catalyst was added to form a reaction mass. The reaction mass was then fed from the feed inlet of a microchannel reactor (model HR-50, corning, usa) into a reaction zone where the molar ratio of methylcyclopentanone to hydrogen peroxide was 1: 4, the weight ratio of the methylcyclopentanone to the tert-butyl alcohol is 1: 4; taking 10mL of cyclohexanone as a reference, the using amount of the composite material particles A1 is 5mg, the reaction temperature is 30 ℃, the pressure is 0.8MPa, the residence time of reaction materials is 2min, collecting a reaction mixture at a discharge hole, carrying out gas chromatography analysis, and calculating the conversion rate of methylcyclopentanone, the effective utilization rate of peroxide and the selectivity of a target product methylglutaric acid. The results are listed in table 1.

Comparative example 1

Cyclohexanone was catalytically oxidized according to the method of example 1, except that the same amount of carbon dots (CDs, particle size 9nm) was used instead of composite particles a 1. The results of the oxidation product analysis are shown in Table 1.

Comparative example 2

Cyclohexanone was catalytically oxidized according to the method of example 1, except that the same amount of titanium oxide (TiO) was used₂Particle size 300nm) was substituted for composite particle a 1. The results of the oxidation product analysis are shown in Table 1.

Comparative example 3

Cyclohexanone was catalytically oxidized by the method of example 1, except that the composite particles a1 were not used as a catalyst. The results of the oxidation product analysis are shown in Table 1.

TABLE 1

Sources of catalyst	Cyclic ketone conversion rate%	Target product selectivity,%	Effective utilization rate of peroxide,%
				Example 1	91.8	86	76
Example 2	89.5	85	74
				Example 3	88.2	83	72
Example 4	85.0	80	69
				Example 5	80.6	77	67
Example 6	93.2	59	50
				Example 7	71.7	32	79
Example 8	86.5	81	71
				Example 9	85.2	80	68
Example 10	61.8	68	74
				Example 11	79.1	76	55
Example 12	82.9	79	66
				Example 13	87.4	81	72
Comparative example 1	20.6	15	24
				Comparative example 2	13.3	12	8
Comparative example 3	8.6	6	5

As can be seen from table 1, the oxidation of cyclic ketone can be achieved under mild conditions by the method of the present disclosure, and the conversion rate of raw materials, the selectivity of target product dicarboxylic acid and the effective utilization rate of peroxide are higher.

The preferred embodiments of the present disclosure have been described in detail above, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A process for the catalytic oxidation of a cyclic ketone, the process comprising: the cyclic ketone and the peroxide are contacted to react in the presence of a catalyst, wherein the catalyst is a catalytic composite material containing carbon dots and titanium oxide, and the content of the carbon dots is 2-40 wt% and the content of the titanium oxide is 60-98 wt% based on the total weight of the catalytic composite material.

2. The method of claim 1, wherein the carbon dots are present in an amount of 5 to 20 wt% and the titanium oxide is present in an amount of 80 to 95 wt%, based on the total weight of the catalytic composite.

3. The method of claim 1, wherein the carbon dots are graphene quantum dots, carbon nanodots, or polymer dots.

4. The method of claim 1, wherein the catalytic composite has a particle size of 10 to 5000nm, preferably 10 to 1000 nm.

5. The method of any one of claims 1 to 4, wherein the step of preparing the catalytic composite comprises:

6. The method of claim 5, wherein in step (1), the molar ratio of the titanium source, first solvent, second solvent, and acid is 1: (0.1-100): (0.1-50): (0.1 to 10); and/or the presence of a gas in the gas,

7. The method of claim 5, wherein the step of preparing the catalytic composite further comprises: in the step (1), adding the first solution into the second solution at a speed of 0.1-50 mL/min; and/or the presence of a gas in the gas,

8. The method according to claim 5, wherein in the step (2), the weight ratio of the third solution to the mixed solution is (0.01-10): 1, preferably (0.1 to 0.8): 1; and/or the presence of a gas in the gas,

9. The method according to any one of claims 1 to 4, wherein the reaction is carried out in a slurry bed reactor, and the amount of the catalyst is 10 to 100mg, preferably 20 to 60mg, based on 10mL of the cyclic ketone; or,

10. The method of any one of claims 1 to 4, further comprising: the reaction is carried out in the presence of a third solvent; the third solvent is water, C1-C6 alcohol, C3-C8 ketone or C2-C6 nitrile, or the combination of two or three of the above; and/or the presence of a gas in the gas,

the weight ratio of the cyclic ketone to the third solvent is 1: (0.1 to 20).

11. The process of any one of claims 1 to 4, wherein the peroxide is hydrogen peroxide, cumene peroxide, cyclohexyl hydroperoxide or tert-butyl hydroperoxide, or a combination of two or three thereof; and/or the presence of a gas in the gas,

the molar ratio of the cyclic ketone to the peroxide is 1: (1 to 10), preferably 1: (2-5); and/or the presence of a gas in the gas,

the cyclic ketone is cyclohexanone, cyclopentanone, methylcyclopentanone or methylcyclohexanone.

12. The method according to any one of claims 1 to 4, wherein the reaction conditions are as follows: the temperature is 0-100 ℃, and preferably 20-80 ℃; the pressure is 0 to 3MPa, preferably 0.1 to 2.5 MPa.