CN111484433B - Process for oxidizing acetic acid - Google Patents
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Abstract
The present disclosure relates to a process for oxidizing acetic acid, the process comprising: and (2) contacting acetic acid and peroxide in the presence of a catalyst to perform oxidation reaction, 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 acetic acid, can realize the oxidation of the acetic acid 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.
Description
Technical Field
The present disclosure relates to a process for oxidizing acetic acid.
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.
Peroxyacetic acid is an organic peroxy compound, a colorless transparent liquid at room temperature, dissolved in water, ethanol, acetone, diethyl ether and chloroform. Peracetic acid is generally prepared by an acetic acid oxidation process, which generally includes a nitric acid oxidation process, a peroxide oxidation process, an ozone oxidation process, an anodic oxidation process, and a nitrogen dioxide oxidation process, depending on the oxidizing agent and oxidation mode 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 peracetic acid and limits the application range of the peroxide oxidation method. Therefore, when acetic acid is oxidized by the peroxide oxidation method, it is an important subject to increase the effective utilization rate of the oxidizing agent and to reduce the production cost of peracetic acid.
Disclosure of Invention
It is an object of the present disclosure to provide a process for oxidizing acetic acid that not only enables higher feedstock conversion and target product selectivity, but also enables higher peroxide availability.
In order to achieve the above object, the present disclosure provides a method of oxidizing acetic acid, the method comprising: the method comprises the following steps of contacting acetic acid and peroxide in the presence of a catalyst to carry out oxidation reaction, wherein the catalyst is a catalytic composite material containing carbon points and titanium oxide, and the content of the carbon points 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,
in the step (1), 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 oxidation reaction is performed in a slurry bed reactor, and the amount of the catalyst is 5-100 mg, preferably 10-80 mg, based on 10mL of the acetic acid; alternatively, the first and second electrodes may be,
the oxidation reaction is carried out in a fixed bed reactor, and the weight hourly space velocity of the acetic acid is 0.01-500 h-1Preferably 0.05 to 2 hours-1(ii) a Alternatively, the first and second electrodes may be,
the oxidation 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 acetic acid; the residence time of the reaction materials is 0.1-15 min.
Optionally, the method further comprises: the oxidation reaction is carried out in the presence of a third solvent; the 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 acetic acid 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 acetic acid to the peroxide is 1: (0.1-2), preferably 1: (0.2 to 1).
Optionally, the oxidation 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.
Through the technical scheme, the catalytic composite material containing carbon dots and titanium oxide is used as the catalyst to catalyze the oxidation reaction of acetic acid, so that the oxidation of the acetic acid can be realized under mild conditions, the conversion rate of raw materials and the selectivity of target products 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 oxidizing acetic acid, the process comprising: and (2) contacting acetic acid and peroxide in the presence of a catalyst to perform oxidation reaction, 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 acetic acid 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. Lattice of the crystalThe obvious carbon quantum dots have obvious quantum size dependence, and the optimal fluorescence emission peak is red-shifted along with the size change from small to large. 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:
(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.
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 may be a titanium-containing compound, 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 thereof. 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 of oxidizing acetic acid of the present disclosure may be carried out in various conventional catalytic reactors, for example, may 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 oxidation 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 acetic acid and peroxide, and for example, the amount of the catalyst may be 5 to 100mg, preferably 10 to 80mg, based on 10mL of the acetic acid.
In another alternative embodiment of the present disclosure, the oxidation reaction may be carried out in a fixed bed reactor. At this time, the weight hourly space velocity of the acetic acid is 0.01-500 h-1Preferably 0.05 to 2 hours-1。
In a preferred embodiment of the present disclosure, the oxidation 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 acetic acid; the residence time of the reaction materials can be 0.1-15 min, wherein the reaction materials refer to a mixture of materials which comprise acetic acid, peroxide, a 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 oxidation reaction is carried out in the presence of a third solvent. The third solvent may be various liquid substances capable of dissolving both acetic acid and peroxide or promoting mixing of both, and promoting dissolution of the target product. Generally, the 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 at least one of water and C1-C6 alcohols. More preferably, the solvent is methanol and/or water. The amount of the third solvent may be appropriately selected depending on the amount of the acetic acid peroxide, and for example, the weight ratio of the acetic acid 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 acetic acid to the peroxide may be 1: (0.1-2), preferably 1: (0.2 to 1).
According to the present disclosure, the conditions of the oxidation 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 oxidation reaction more sufficient, it is preferable that the oxidation reaction is carried out under stirring.
The process of the present disclosure may further comprise the step of separating the peroxyacetic acid containing mixture obtained from the oxidation reaction to separate the peroxyacetic acid therefrom. The method for separating peroxyacetic acid from the mixture obtained by the oxidation reaction in the present disclosure is not particularly limited, and may be a routine choice in the art. For example, peroxyacetic acid can be obtained by subjecting the mixture obtained by the reaction to fractional distillation.
The catalytic composite material containing carbon dots and titanium oxide is used as the catalyst to catalyze the oxidation reaction of acetic acid, so that the oxidation of the acetic acid can be realized under mild conditions, the conversion rate of raw materials and the selectivity of a target product are high, the effective utilization rate of peroxide can be obviously improved, and the production cost is reduced.
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
Stirring tetrabutyl titanate and first solvent absolute ethyl alcohol strongly10min (stirring speed 800 rpm) gave 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 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 0.5: 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 1-12 are provided to illustrate the process of oxidizing acetic acid of the present disclosure.
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:
acetic acid conversion (%)% of acetic acid (molar amount of acetic acid added before reaction-molar amount of acetic acid remaining after reaction)/molar amount of acetic acid added before reaction × 100%;
the selectivity of peroxyacetic acid is defined as the molar amount of peroxyacetic acid generated after the reaction/the molar amount of acetic acid added before the reaction x 100%;
the peroxide effective utilization ratio%.
Example 1
Acetic acid, 30 wt% hydrogen peroxide and methanol as a solvent were mixed and composite particles a1 as a 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 acetic acid to hydrogen peroxide was 1: 1, the weight ratio of acetic acid to methanol is 1: 4; the dosage of the composite material particles A1 is 2mg, the reaction temperature is 30 ℃, the pressure is 0.8MPa, the residence time of the reaction materials is 5min, the reaction mixture is collected at a discharge port for gas chromatography analysis, and the conversion rate of acetic acid, the effective utilization rate of peroxide and the selectivity of target product peroxyacetic acid are calculated. The results are listed in table 1.
Examples 2 to 5
Acetic acid was catalytically oxidized by the method of example 1, except that the same amounts of the composite particles A2 to A5 were used instead of A1, respectively. The results of the oxidation product analysis are shown in Table 1.
Example 6
Acetic acid was catalytically oxidized according to the procedure of example 1, except that the molar ratio of acetic acid to hydrogen peroxide was 1: 2, the weight ratio of acetic acid to methanol is 1: 20; the amount of composite particles A1 was 25mg based on 10mL of acetic acid. The results of the oxidation product analysis are shown in Table 1.
Example 7
Acetic acid was catalytically oxidized according to the procedure of example 1, except that the molar ratio of acetic acid to hydrogen peroxide was 1: 0.1, the weight ratio of acetic acid to methanol is 1: 0.8; the amount of composite particles A1 was 0.2mg based on 10mL of acetic acid. The results of the oxidation product analysis are shown in Table 1.
Example 8
Acetic acid, 30 wt% hydrogen peroxide and methanol as a 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 acetic acid to hydrogen peroxide was 1: 1, the weight ratio of acetic acid to methanol is 1: 4; the reaction temperature is 30 ℃, the pressure is 0.8MPa, and the weight hourly space velocity of the acetic acid 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 the composite particles a1 as a catalyst and 10mL of acetic acid were charged into a 250mL autoclave, to which were then added 30% by weight of hydrogen peroxide and methanol as a solvent, the molar ratio of acetic acid to hydrogen peroxide being 1: 1, the weight ratio of acetic acid 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
Acetic acid was catalytically oxidized according to the method of example 9, except that the amount of the composite particles A1 was 5 mg. The results of the oxidation product analysis are shown in Table 1.
Example 11
Acetic acid was catalytically oxidized according to the method of example 9, except that the amount of the composite particles A1 was 85 mg. The results of the oxidation product analysis are shown in Table 1.
Example 12
Acetic acid 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.
Comparative example 1
Acetic acid was catalytically oxidized according to the method of example 1, except that the same amount of carbon dots (CDs, particle size 9nm) was used in place of the composite particles a 1. The results of the oxidation product analysis are shown in Table 1.
Comparative example 2
Acetic acid 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
Acetic acid 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 | Acetic acid conversion rate% | Peracetic acid selectivity,% | Effective utilization rate of peroxide,% |
| Example 1 | 96.8 | 96 | 94 |
| Example 2 | 95.5 | 95 | 93 |
| Example 3 | 91.3 | 93 | 89 |
| Example 4 | 88.2 | 92 | 86 |
| Example 5 | 85.6 | 91 | 83 |
| Example 6 | 90.1 | 93 | 88 |
| Example 7 | 88.2 | 91 | 86 |
| Example 8 | 89.9 | 92 | 90 |
| Example 9 | 87.2 | 91 | 84 |
| Example 10 | 84.3 | 88 | 80 |
| Example 11 | 84.8 | 89 | 81 |
| Example 12 | 89.5 | 92 | 85 |
| Comparative example 1 | 56.3 | 73 | 45 |
| Comparative example 2 | 20.2 | 65 | 17 |
| Comparative example 3 | 20.8 | 62 | 21 |
As can be seen from table 1, the oxidation of acetic acid can be achieved under mild conditions with higher feedstock conversion, target product selectivity and peroxide availability using the disclosed process.
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 (18)
1. A process for oxidizing acetic acid to produce peroxyacetic acid, the process comprising: the method comprises the following steps of contacting acetic acid and peroxide in the presence of a catalyst to carry out oxidation reaction, wherein the catalyst is a catalytic composite material containing carbon points and titanium oxide, and the content of the carbon points 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 5000 nm.
5. The method of claim 4, wherein the catalytic composite has a particle size of 10 to 1000 nm.
6. The method of any one of claims 1 to 5, wherein 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) 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;
wherein the first solvent is ethanol, n-propanol, isopropanol, n-butanol, tert-butanol or cyclohexanol, or a combination of two or three of them;
the second solvent is water, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol or cyclohexanol, or a combination of two or three of them.
7. The method of claim 6, 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,
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 them.
8. The method of claim 6, 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,
in the step (1), the stirring conditions include: the stirring speed is 100-2000 rpm, and the time is 0.1-12 h.
9. The method according to claim 8, wherein the stirring speed is 200-1000 rpm and the time is 0.5-6 h.
10. The method according to claim 6, wherein in the step (2), the weight ratio of the third solution to the mixed solution is (0.01-10): 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.
11. The method according to claim 10, wherein in the step (2), the weight ratio of the third solution to the mixed solution is (0.1-0.8): 1.
12. the method according to any one of claims 1 to 5, wherein the oxidation reaction is carried out in a slurry bed reactor, and the amount of the catalyst is 5 to 100mg based on 10mL of the acetic acid; alternatively, the first and second electrodes may be,
the oxidation reaction is carried out in a fixed bed reactor, and the weight hourly space velocity of the acetic acid is 0.01-500 h-1(ii) a Alternatively, the first and second electrodes may be,
the oxidation reaction is carried out in a microchannel reactor, 10mL of the acetic acid is taken as a reference, and the dosage of the catalyst is 0.2-50 mg; the residence time of the reaction materials is 0.1-15 min.
13. The method according to claim 12, wherein the oxidation reaction is carried out in a slurry bed reactor, and the amount of the catalyst is 10-80 mg based on 10mL of the acetic acid; alternatively, the first and second electrodes may be,
the oxidation reaction is carried out in a fixed bed reactor, and the weight hourly space velocity of the acetic acid is 0.05-2 h-1(ii) a Alternatively, the first and second electrodes may be,
the oxidation reaction is carried out in a microchannel reactor, and the dosage of the catalyst is 0.5-20 mg based on 10mL of the acetic acid.
14. The method of any one of claims 1 to 5, further comprising: the oxidation 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;
the weight ratio of the acetic acid to the third solvent is 1: (0.1 to 20).
15. A process according to any one of claims 1 to 5, 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 acetic acid to the peroxide is 1: (0.1-2).
16. The method according to claim 15, wherein the molar ratio of the acetic acid to the peroxide is 1 (0.2-1).
17. The method according to any one of claims 1 to 5, wherein the oxidation reaction conditions are: the temperature is 0-100 ℃; the pressure is 0-3 MPa.
18. The method according to claim 17, wherein the temperature is 20 to 80 ℃ and the pressure is 0.1 to 2.5 MPa.
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