CN108993591B - Preparation method of carbon quantum dot doped deca-poly quaternary ammonium tungstate - Google Patents

Preparation method of carbon quantum dot doped deca-poly quaternary ammonium tungstate Download PDF

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CN108993591B
CN108993591B CN201810748001.2A CN201810748001A CN108993591B CN 108993591 B CN108993591 B CN 108993591B CN 201810748001 A CN201810748001 A CN 201810748001A CN 108993591 B CN108993591 B CN 108993591B
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CN108993591A (en
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伏再辉
苏安群
张超
杨波
陈梦柯
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Hunan Normal University
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Abstract

The invention relates to the field of synthesis of photocatalytic materials, and discloses a preparation method of carbon quantum dot doped quaternary ammonium decatungstate and a conversion system for selectively oxidizing organic matters by using molecular oxygen under high-efficiency visible light catalysis based on the quaternary ammonium decatungstate as a catalyst. Sodium tungstate dihydrate and oxygen-containing, nitrogen-containing or nitrogen-oxygen-containing carbon quantum dots are used as raw materials to synthesize a series of deca-poly ammonium tungstate catalysts with carbon quantum dots of different doping amounts. The preparation method is simple, the synthesized catalyst has high quality, and the catalyst can efficiently catalyze molecular oxygen to selectively oxidize cyclohexane, toluene, ethylbenzene and benzyl alcohol to synthesize corresponding oxygen-containing organic matters in acetonitrile, particularly acetonitrile medium containing acidic aqueous solution and under the irradiation of visible light.

Description

Preparation method of carbon quantum dot doped deca-poly quaternary ammonium tungstate
Technical Field
The invention relates to a preparation method of a carbon quantum dot doped deca-poly quaternary ammonium tungstate catalyst
Background
Selective oxidation of organic matter is a very important type of conversion reaction because its oxygen-containing products have been widely used industrially as bulk chemicals and key intermediates. For example, cyclohexanone and cyclohexanol (KA oil) synthesized by selective oxidation of cyclohexane are important raw materials for the preparation of chemical fibers and fine chemicals. The traditional oxidation method requires harsh conditions, the cyclohexane conversion rate is not high, the yield of KA oil is low, the energy consumption is high, and the pollution is serious, so that the development of a new cyclohexane oxidation system is always a hot spot and a difficult problem for research of chemical workers. Decatungstate has good photo-oxidation catalytic activity on saturated hydrocarbon under oxygen atmosphere [ chem.Commun.2000, (2):381-382], so that the application of decatungstate as a photocatalyst in organic chemical reactions is an active research subject in the field of polyacid chemistry in recent years. Tetraethylammonium decatungstate, diisopropylammonium decatungstate, and piperidine decatungstate were used for photocatalytic oxidation of cyclohexane with only about 5% conversion [ proceedings of the university of Huaqiao, 2002,3(3):300-303 ]. The quaternary ammonium tetrabutyl decatungstate is used as a catalyst, cyclohexane is oxidized by molecular oxygen under visible light, the conversion rate is about 8 percent, the quantum efficiency is still low, and the research before the subject group finds that if water and acid are added into the system as an auxiliary agent, the conversion rate of the cyclohexane can be greatly improved to about 20 percent, and the selectivity of the cyclohexanone is also improved to 75 percent [ appl.Catal.B-environ.164(2015)113-119 ]. Therefore, the optimized design of the quaternary ammonium decatungstate is continued, and the method is an effective idea for improving the catalytic performance of the quaternary ammonium decatungstate.
Carbon element is one of the most abundant elements in nature, and in recent years, carbon nanomaterials have gradually become a research hotspot in nanotechnology. The carbon quantum dot is a novel zero-dimensional carbon nano material with fluorescence property, and the size of the carbon quantum dot is 1-10 nm. Compared with the traditional carbon material, the carbon material has the advantages of low manufacturing and separating cost, high stability and better water solubility due to more hydrophilic groups on the surface. Research shows that the carbon quantum dots have an sp2 hybridized conjugated system, fluorescence emitted in an aqueous solution can be effectively quenched by an electron donor or an electron acceptor, and the carbon quantum dots have good electron transfer performance [ chem. 3774-3776]. HU et al, the carbon quantum dots produced by electrochemical oxidation and TiO2The activity of the photocatalyst for hydrogen production is greatly improved by compounding the components (J.Mater.Chem.A.2014, 2, 3344-3351)](ii) a Zhang et al, to dot carbon quantum dots with Ag3PO4The catalyst obtained by compounding is used for photocatalytic degradation of methyl orange and the light of carbon quantum dotsThe transfer of the generated electrons effectively protects Ag3PO4Is not corroded by light, and improves the stability of the photocatalysis process [ J.Mater.chem.2012, 22, 10501-]. Therefore, the excellent performance of the carbon quantum dots in the catalysis field is used for modifying the quaternary ammonium decatungstate, and the effective idea of improving the quantum yield and the catalysis stability is provided.
Disclosure of Invention
The invention aims to provide a method for synthesizing a carbon quantum dot modified quaternary ammonium decatungstate catalyst. The carbon quantum dot modified catalyst provided by the invention is used for synthesizing an oxygen-containing product by selectively oxidizing an organic matter by using visible light to catalyze molecules, and has excellent conversion rate and target product selectivity.
The preparation method of the carbon quantum dot modified polyacid quaternary ammonium salt comprises the following two modes:
the first mode is as follows: adding different self-made carbon quantum dots and organic quaternary ammonium salt into deionized water according to a certain proportion, ultrasonically dissolving, transferring to a polytetrafluoroethylene reaction kettle, carrying out hydrothermal reaction for a period of time at a certain temperature to obtain a carbon quantum dot modified organic quaternary ammonium salt intermediate, and carrying out exchange reaction with a decatungstate solution under a certain pH condition to obtain the carbon quantum dot modified decatungstate quaternary ammonium salt catalyst.
The second mode is as follows: dissolving sodium tungstate dihydrate in water, heating and boiling, adjusting pH value with hydrochloric acid, adding organic quaternary ammonium salt to generate a large amount of precipitate,
transferring the precipitate and the self-made carbon quantum dot solution into a polytetrafluoroethylene reaction kettle, and carrying out hydrothermal reaction for a certain time at a certain temperature to obtain the carbon quantum dot modified quaternary ammonium decatungstate catalyst.
The organic quaternary ammonium salt is tetramethyl, tetraethyl, tetrapropyl, tetrabutyl chloride or ammonium bromide.
The carbon quantum dots are oxygen-containing carbon quantum dots prepared by citric acid hydrothermal reaction, nitrogen-containing carbon quantum dots prepared by citric acid and ethylenediamine hydrothermal reaction, oxygen-containing carbon quantum dots prepared by electrochemical graphite oxide rods, and C3N4One of the quantum dots is deca-poly quaternary ammonium tungstate0.1-10 wt% of the mass. Preferably, the carbon quantum dots are used in an amount of 3 wt%.
In the mode (1), the mass ratio of the carbon quantum dots to the organic quaternary ammonium salt is preferably 1: (100 to 400), more preferably 1: (100-200), and most preferably 1: 135.
In the mode (2), the mass ratio of the carbon quantum dots to the tetrabutyl decatungstate quaternary ammonium salt is preferably 1: (100 to 500), more preferably 1: (100-200), and most preferably 1: 165.
The hydrothermal reaction time in the mode (1) or (2) is preferably 6 to 36 hours, more preferably 12 to 24 hours, and most preferably 24 hours.
The hydrothermal reaction temperature in the above-mentioned manner (1) or (2) is preferably 80 to 150 ℃, more preferably 100 ℃ to 120 ℃, most preferably 100 ℃.
The pH is preferably 1.6-2.8, more preferably 1.8-2.5, most preferably 2.3.
The invention provides a method for synthesizing a carbon quantum dot modified quaternary ammonium decatungstate catalyst. The carbon quantum dot modified catalyst provided by the invention is used for synthesizing oxygen-containing chemicals by selectively oxidizing organic matters by using visible light to catalyze molecules, and has excellent conversion rate and selectivity. According to the experimental results of the embodiment, in the reaction of preparing KA oil by catalytic oxidation of cyclohexane, the carbon quantum dot modified quaternary ammonium decatungstate catalyst provided by the application has the advantages that the cyclohexane conversion rate is increased to 20%, the cyclohexane conversion rate is increased to 30% under the promotion of auxiliary water and hydrochloric acid, and the selectivity of cyclohexanone is increased to 85%.
Drawings
FIG. 1 is a fluorescence spectrum of oxygen and nitrogen carbon quantum dots doped tetrabutylammonium decatungstate prepared as described in example 1 and tetrabutylammonium decatungstate prepared as comparative example 1.
Detailed Description
The following examples are provided to describe the synthesis method of the carbon quantum dot modified tetrabutylammonium decatungstate catalyst in detail, but they should not be construed as limiting the scope of the present invention.
Example 1(1-1 to 1-4):
the carbon quantum dot modified tetrabutylammonium decatungstate is prepared according to the following two steps:
step (1): mixing solutions respectively containing 10mg, 20mg, 30mg and 40mg of nitrogen and oxygen carbon quantum dots prepared by citric acid and ethylenediamine through a water method according to a literature report (Angew. chem. int. Ed.2013,52, 3953-;
step (2): 6.4g of sodium tungstate dihydrate and 40mL of deionized water are added into a 100mL round bottom flask with a stirrer, the flask is heated to boiling, 3mol/L of hydrochloric acid is rapidly added, the pH value is adjusted to be about 2.3, and the flask is refluxed in an oil bath at 100 ℃ for 10 min. And (2) dropwise adding the tetrabutylammonium bromide solution subjected to carbon dot treatment and prepared in the step (1), controlling the pH value to be stable at 2.3, generating a large amount of brown precipitate, and continuing to react for 30min after dropwise adding is completed to obtain a catalyst solid. Washing with deionized water and ethanol, filtering, and vacuum drying at 60 ℃ to obtain the carbon quantum dot modified tetrabutylammonium decatungstate catalyst.
Comparative example 1: the resulting tetrabutylammonium decatungstate was prepared by the preparation method described in example 1, except that tetrabutylammonium bromide solution which was not treated with carbon quantum dots was used in step (2).
FIG. 1 is fluorescence spectra of oxygen and nitrogen-containing carbon quantum dots doped tetrabutylammonium decatungstate prepared in example 1 and tetrabutylammonium decatungstate prepared in comparative example 1, and shows that photoluminescence fluorescence spectrum intensity of the tetrabutylammonium decatungstate is significantly decreased as the doping amount of the carbon quantum dots is increased (curve 2-5). The carbon quantum dot doping can obviously improve the stability of the photoexcited state of the tetrabutylammonium decatungstate, thereby obviously improving the photocatalytic oxidation activity.
Dissolving 1.2% mmol of the product in 5.5mL of acetonitrile, and taking pure oxygen as an oxidant, wherein the reaction temperature is 35 ℃. Under the conditions of normal pressure (1atm) and condensation, 1mmol of cyclohexane is catalytically oxidized under the irradiation of visible light of a 35W halogen tungsten lamp for 12 hours, and a reaction product is analyzed by gas chromatography. Specific results are shown in table 1.
TABLE 1
Figure GDA0002983356670000041
As can be seen from Table 1, when the method of the invention is used for doping the ammonium decatungstate catalyst with oxygen-containing and nitrogen-carbon quantum dots, the conversion rate of the photocatalytic oxidation of cyclohexane can reach 17.40-21.73%, and the selectivity of cyclohexanone can also reach 83-89%, and both the conversion rate and the selectivity are far higher than the reaction result of the undoped catalyst prepared in the comparative example 1.
Example 2(2-1 to 2-4):
step (1): preparing an aqueous solution of tetrabutyl decatungstate quaternary ammonium salt precipitate by the method described in comparative example 1;
step (2): and (2) respectively dropwise adding 10mg, 20mg, 30mg and 40mg of oxygen-containing and nitrogen-containing carbon quantum dot aqueous solutions prepared from citric acid and ethylenediamine into the precipitation solution prepared in the step (1), controlling the pH to be 2.3, continuously stirring and refluxing for 30min, and then transferring to a 100ml polytetrafluoroethylene reaction kettle to perform hydrothermal reaction at 100 ℃ for 24 h. And after cooling, washing and suction-filtering by using deionized water and ethanol, and vacuum-drying at 60 ℃ to obtain the carbon quantum dot modified tetrabutylammonium decatungstate catalyst.
The catalysts prepared in the above examples 2-1 to 2-4 were evaluated for the photocatalytic selective oxidation of cyclohexane by molecular oxygen according to the method described in [0021], and the specific results are shown in Table 2.
TABLE 2
Figure GDA0002983356670000042
As can be seen from Table 2, the ammonium decatungstate catalyst prepared by the method of the invention can achieve 12.41-19.25% of conversion rate of photocatalytic oxidation cyclohexane and 70-89% of selectivity of cyclohexanone through hydrothermal treatment of nitrogen-containing carbon quantum dots.
Example 3(3-1 to 3-4):
an oxygen-and nitrogen-carbon quantum dot-doped decatungstate catalyst was prepared as described in example 1, except that the temperatures of the hydrothermal reaction of the carbon quantum dot and tetrabutylammonium bromide mixed solution in step (1) in a polytetrafluoroethylene reaction vessel were set to 80 ℃, 110 ℃, 120 ℃ and 150 ℃, respectively.
The catalysts prepared in examples 3-1 to 3-4 were subjected to evaluation of photocatalytic molecular oxygen selective oxidation of cyclohexane by the method described in [0021], and the specific results are shown in Table 3.
TABLE 3
Figure GDA0002983356670000051
As can be seen from Table 3, the nitrogen-containing carbon quantum dot modified ammonium decatungstate catalyst prepared by the method of the invention at different temperatures has a conversion rate of photocatalytic oxidation of cyclohexane of 19-21% and a selectivity of cyclohexanone of 82-83%.
Example 4(4-1 to 4-4):
an oxygen-and nitrogen-containing carbon quantum dot-doped decatungstate catalyst was prepared as described in example 1, except that the hydrothermal reaction time of the mixed solution of the carbon quantum dots and tetrabutylammonium bromide in the polytetrafluoroethylene reaction vessel in step (1) was set to 6, 12, 18 and 36 hours, respectively.
The catalysts prepared in examples 4-1 to 4-4 were evaluated for the photocatalytic selective oxidation of cyclohexane by molecular oxygen according to [0021], and the specific results are shown in Table 4.
TABLE 4
Figure GDA0002983356670000052
As can be seen from Table 4, the nitrogen-containing carbon quantum dot modified ammonium decatungstate catalyst prepared by the method of the invention in different reaction times has a conversion rate of photocatalytic oxidation of cyclohexane of 10-20%, and a selectivity of cyclohexanone of 76-82%.
Example 5(5-1 to 5-3):
an oxygen and nitrogen-containing carbon quantum dot-doped decatungstate catalyst was prepared as described in example 1, except that the pH was set to 1.8, 2.0, and 2.8 in step (2), respectively.
The catalysts prepared in examples 5-1 to 5-3 were subjected to evaluation of photocatalytic molecular oxygen selective oxidation of cyclohexane by the method described in [0021], and the specific results are shown in Table 5.
TABLE 5
Figure GDA0002983356670000061
As can be seen from Table 5, the nitrogen-containing carbon quantum dot modified ammonium decatungstate catalyst prepared by the method of the invention under different pH conditions has a conversion rate of photocatalytic oxidation of cyclohexane of 9-21% and a selectivity of cyclohexanone of 76-82%.
Example 6:
an oxycarbon quantum dot doped decatungstate catalyst was prepared as described in example 1, except that the oxycarbon quantum dots used in step (1) were prepared using graphite rods by electrochemical oxidation (Dalton trans.,2012,41, 9526-9531).
The catalyst prepared in example 6 was evaluated for the photocatalytic selective oxidation of cyclohexane by molecular oxygen as described in [0021], except that the effect of the addition of water, hydrochloric acid and a mixture thereof on the photocatalytic performance was examined, and the results are shown in Table 6.
TABLE 6
Figure GDA0002983356670000062
As can be seen from Table 6, the oxygen-carbon-containing quantum dot modified ammonium decatungstate catalyst prepared by the method provided by the invention has a conversion rate of photocatalytic oxidation of cyclohexane of 11%; when concentrated hydrochloric acid is added, the conversion rate can reach 13 percent; when water is used as an additive, the conversion rate can reach 15 percent; meanwhile, hydrochloric acid and deionized water are added as auxiliary agents, the conversion rate of cyclohexane can reach 23%, and the selectivity of cyclohexanone can also reach 76-83%.
Example 7:
an oxygen-containing carbon quantum dot-doped decatungstate catalyst was prepared as described in example 1, except that the oxygen-containing carbon quantum dots used in step (1) were prepared by a citric acid water thermal carbonization method (angelw.chem.int.ed.2013, 52, 1-6).
The catalyst prepared in example 7 was evaluated for the photocatalytic selective oxidation of cyclohexane by molecular oxygen as described in [0021], except that the effect of the addition of water, hydrochloric acid and a mixture thereof on the photocatalytic performance was examined, and the specific results are shown in Table 7.
TABLE 7
Figure GDA0002983356670000071
As can be seen from Table 7, the oxygen-carbon-containing quantum dot modified ammonium decatungstate catalyst prepared by the method of the invention has the advantage that the conversion rate of cyclohexane photocatalytic oxidation can reach 10%; when concentrated hydrochloric acid is added, the conversion rate can reach 13 percent; when water is used as an additive, the conversion rate can reach 16 percent; meanwhile, hydrochloric acid and deionized water are added as auxiliary agents, the conversion rate of cyclohexane can reach 22%, and the selectivity of cyclohexanone can also reach 73-80%.
Example 8:
preparation C as described in example 13N4Quantum dot doped ammonium decatungstate catalyst, except that C is used in step (2)3N4Quantum dots are prepared by ultrasonic lift-off method (j. mater. chem.,2011,21, 14398-.
The catalyst prepared in example 8 was evaluated for the photocatalytic selective oxidation of cyclohexane by molecular oxygen as described in [0021], except that the effect of the addition of water, hydrochloric acid and a mixture thereof on the photocatalytic performance was examined, and the results are shown in Table 8.
TABLE 8
Figure GDA0002983356670000072
As can be seen from Table 8, C prepared by the method described in the invention3N4The quantum dot modified ammonium decatungstate catalyst has the advantage that the conversion rate of cyclohexane photocatalytic oxidation can reach 14%; when concentrated hydrochloric acid is added, the conversion rate can reach 15 percent; when water is used as an additive, the conversion rate can reach 18 percent; meanwhile, hydrochloric acid and deionized water are added as auxiliary agents, the conversion rate of cyclohexane can reach 24%, and the selectivity of cyclohexanone can also reach 74-79%.
Example 9(9-1 to 9-4):
an oxygen and nitrogen-containing, nitrogen-carbon quantum dot-doped decatungstate catalyst was prepared as described in example 1, except that the organic quaternary ammonium salts used were tetramethyl ammonium bromide, tetraethyl ammonium bromide and tetrapropyl ammonium bromide.
The catalyst prepared in example 9 was evaluated for the photocatalytic selective oxidation of cyclohexane by molecular oxygen as described in [0021], except that the effect of the mixture of water (0.5ml) and hydrochloric acid (2mmol) on the photocatalytic performance was examined, and the results are shown in Table 9.
TABLE 9
Figure GDA0002983356670000081
Test example 1(1-1 to 1-5):
the catalyst used in this test example was the oxygen-and nitrogen-containing carbon quantum dot-doped decatungstate catalyst prepared by the method described in example 1, and the performance of this catalyst in photocatalytic selective oxidation of cyclohexane by molecular oxygen was evaluated by the method described in [0021], except that the effect of the amount of the catalyst on the photocatalytic performance was examined, and the specific results are shown in table 10.
Watch 10
Figure GDA0002983356670000082
Test example 2(2-1 to 2-5):
the catalyst used in this test example was the oxygen and nitrogen-containing carbon quantum dot doped decatungstate catalyst prepared as described in example 1, as [0021]]The method evaluates the performance of the catalyst in photocatalytic molecular oxygen selective oxidation, except that 2mmol of HCl, HAc and PhSO are respectively added3H，H3PO4Or, H2SO4And the effect of 0.5ml of water on its photocatalytic oxygen performance, the specific results are shown in Table 11.
TABLE 11
Figure GDA0002983356670000091
Test example 3(3-1 to 3-5):
the catalyst used in this test example was the oxygen-and nitrogen-containing carbon quantum dot-doped decatungstate catalyst prepared as described in example 1, and the performance of this catalyst in photocatalytic oxidation of cyclohexane by molecular oxygen was evaluated as described in [0021], except that the effect of the amount of concentrated hydrochloric acid used as an additive on the reaction results was examined, and the specific results are shown in table 12.
TABLE 12
Figure GDA0002983356670000092
Test example 4(4-1 to 4-6):
the catalyst used in this test example was the oxygen-and nitrogen-containing carbon quantum dot-doped decatungstate catalyst prepared by the method described in example 1, and the performance of the catalyst in photocatalytic oxidation of cyclohexane by molecular oxygen was evaluated by the method described in [0021], except that the influence of the amount of water used as an additive on the reaction results was examined, and the specific results are shown in table 13.
Watch 13
Figure GDA0002983356670000093
Test example 5(5-1 to 5-6):
the catalyst used in this test example was the oxygen-and nitrogen-containing carbon quantum dot-doped decatungstate catalyst prepared by the method described in example 1, and the performance of the catalyst in photocatalytic selective oxidation of cyclohexane by molecular oxygen was evaluated by the method described in [0021], except that the influence of the light irradiation time on the reaction result was examined, and the specific results are shown in table 14.
TABLE 14
Figure GDA0002983356670000101
Test example 6(6-1 to 6-5):
the catalyst used in this test example was the oxygen-and nitrogen-carbon-containing quantum dot-doped decatungstate catalyst prepared by the method described in example 1, and the performance of the catalyst in photocatalytic selective oxidation of cyclohexane by molecular oxygen was evaluated by the method described in [0021], except that the influence of the power of the light source halogen tungsten lamp on the reaction result was examined, and the specific results are shown in table 15.
Watch 15
Figure GDA0002983356670000102
Test example 7:
the catalyst used in this test example was an oxygen-and nitrogen-containing carbon quantum dot-doped decatungstate catalyst prepared as described in example 1, and the performance of this catalyst in photocatalytic molecular oxygen selective oxidation of cyclohexane was evaluated as described in [0021], except that the effect of using air as the oxidizing agent on the reaction results was examined and the gas chromatography result showed a cyclohexane conversion of 7.56%.
Test example 8:
the catalyst used in this test example was an oxygen-and nitrogen-containing carbon quantum dot-doped decatungstate catalyst prepared as described in example 1, and the performance of this catalyst in photocatalytic molecular oxygen selective oxidation of cyclohexane was evaluated as described in [0021], except that the effect of an oxygen pressure of 2atm on the reaction results was examined, and the gas chromatography result showed a cyclohexane conversion of 25.68%.
Test example 9(9-1 to 9-8):
the catalyst used in this test example was an oxygen-and nitrogen-containing carbon quantum dot-doped decatungstate catalyst prepared as described in example 1, and the performance of the catalyst in photocatalytic selective oxidation of molecular oxygen was evaluated as described in [0021], except that the effects of various reaction substrates cyclohexane, toluene, ethylbenzene and benzyl alcohol, and water, hydrochloric acid and a mixture thereof as additives were examined, and the specific results are shown in Table 16.
TABLE 16
Figure GDA0002983356670000111
From the above examples, the invention provides a method for synthesizing a catalyst of carbon quantum dot modified quaternary ammonium decatungstate. Compared with a deca-poly-ammonium tungstate catalyst before modification, the conversion rate of cyclohexane is improved from 8% to about 20%, and the selectivity of cyclohexanone is improved to about 85%.
The foregoing is only a preferred embodiment of the present invention and several modifications may be made without departing from the spirit of the invention and these modifications should also be construed as within the scope of the invention.

Claims (8)

1. A preparation method of a carbon quantum dot doped quaternary ammonium decatungstate photocatalyst comprises the following steps:
adding self-made organic quaternary ammonium salts with different carbon quantum dots and different carbon chain lengths into deionized water according to a certain proportion, ultrasonically dissolving, transferring into a polytetrafluoroethylene reaction kettle, carrying out hydrothermal reaction for a period of time at a certain temperature to obtain a carbon quantum dot modified organic quaternary ammonium salt intermediate, and carrying out exchange reaction with a pre-synthesized decatungstate solution under a certain pH condition to obtain the carbon quantum dot doped decatungstate quaternary ammonium salt photocatalyst.
2. The preparation method according to claim 1, wherein the carbon quantum dot is one of an oxygen-containing carbon quantum dot prepared by a citric acid hydrothermal method, a nitrogen-containing carbon quantum dot prepared by hydrothermal reaction of citric acid and ethylenediamine, and an oxygen-containing carbon quantum dot prepared by electrochemical oxidation of graphite rod, and the amount of the oxygen-containing carbon quantum dot is 0.1-10 wt% of the mass of the quaternary ammonium decatungstate.
3. The preparation method according to claim 1, wherein the hydrothermal reaction temperature is 80-150 ℃ and the hydrothermal reaction time is 6-30 h.
4. The method according to claim 1, wherein the hydrothermal reaction solution has a pH of 1.8 to 2.8.
5. A method for synthesizing oxygen-containing chemicals by selectively oxidizing organic matters under visible light catalysis comprises the step of using the carbon quantum dot doped quaternary ammonium decatungstate photocatalyst disclosed in claim 1, wherein the organic matters are used as a substrate, the organic matters are one of cyclohexane, toluene, ethylbenzene and benzyl alcohol, 0.1-0.2MPa of air and molecular oxygen are used as oxidants, acetonitrile is used as a reaction medium, water and an acidic aqueous solution are used as additives, the acidic aqueous solution is one of hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid and benzenesulfonic acid, a 15-60W halogen tungsten lamp is used as a light source, a light source built-in photoreactor is used, and the continuous light irradiation reaction is carried out for 3-18 hours at 15-35 ℃ under the condition of magnetic stirring.
6. The method of claim 5, wherein the amount of the carbon quantum dot doped quaternary ammonium decapolytungstate photocatalyst is 0.1-2.5 mmol% of the reaction substrate.
7. The method of claim 5, wherein the concentration of the organic compound in the acetonitrile solution is 0.2 to 1.0 mol/L.
8. The method according to claim 5, wherein the amount of water as the additive is 1.0 to 9.0mol/L and the molar amount of the aqueous acidic solution is 1 to 5 times the molar amount of the substrate.
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CN115636726B (en) * 2022-10-21 2024-05-10 湖南师范大学 Method for producing hydrogen and oxygen-containing organic matter by virtue of economic reaction of visible light catalytic hydrocarbon compound and water source at normal temperature

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