CN111389398A - Preparation method of hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalyst - Google Patents

Preparation method of hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalyst Download PDF

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CN111389398A
CN111389398A CN202010191532.3A CN202010191532A CN111389398A CN 111389398 A CN111389398 A CN 111389398A CN 202010191532 A CN202010191532 A CN 202010191532A CN 111389398 A CN111389398 A CN 111389398A
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cps
sio
cuprous oxide
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hollow silica
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CN111389398B (en
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尹正亮
曹顺生
陈刚
肖颖冠
时庆叶
张宣宣
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Jiangsu University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/72—Copper
    • B01J35/39—
    • B01J35/51—
    • B01J35/60—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/16—Reducing
    • B01J37/18—Reducing with gases containing free hydrogen
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
    • C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
    • C07C209/325—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups reduction by other means than indicated in C07C209/34 or C07C209/36

Abstract

The invention relates to a visible-light-driven photocatalyst, in particular to a preparation method of a hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalyst. Firstly, copper ions are uniformly loaded on CPS @ SiO in an adsorption-evaporation manner2On the surfaceThen CPS @ SiO2‑Cu2+Preparing SiO for the template2Outer layer (CPS @ SiO)2‑Cu2+@SiO2) Calcining at high temperature to remove CPS template, and regulating temperature under Ar/H2And reducing the copper oxide into cuprous oxide under the atmosphere. The visible-light-driven photocatalyst prepared by the invention is used for realizing the purpose of efficiently and selectively reducing the nitroaromatic into the corresponding aniline, so as to solve the technical problem that the prior photocatalyst can not realize the efficient and selective reduction of the nitroaromatic in a visible light and pure water system.

Description

Preparation method of hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalyst
Technical Field
The invention relates to a visible light catalyst, in particular to a simple preparation technology of a novel limited-area visible light catalyst, in particular to a preparation method of a hierarchical hollow silica limited-area cuprous oxide visible light catalyst, which is a preparation method of a hierarchical hollow silica supported cuprous oxide semiconductor catalyst and an application of the visible light catalyst in visible light catalytic reduction of nitroarene.
Background
Aromatic amines are important industrial raw materials and organic intermediates, and are widely used in the fields of medicines, pesticides, dyes, and the like (p. zhou, et al, High performance of a cobalt-nitro composition for thermal and reactive coupling of nitro compositions in amines and the same properties, sci. adv.2017,3, e 1601945). Therefore, how to realize the high-efficiency conversion of the paranitroarene is extremely important. At present, the traditional thermal catalytic reduction method for producing aromatic amine in industry is still the most common method, however, the catalytic reduction technology still faces some challenges such as high hydrogen pressure, low safety factor of reducing agent (hydrazine hydrate and the like), high temperature, dependence on organic catalytic system and the like. Obviously, these catalytic conditions not only increase the production costs, but also cause serious environmental hazards. Particularly, when the reduction of functional nitroaromatic containing two or more reactive groups is involved, a large amount of side reactions occur, which not only can cause more by-products to affect the production efficiency, but also can improve the purification difficulty of target products and increase the loss in the product separation process. In addition, for nitroarenes containing some special functional groups (such as-Cl, -C ═ C, etc.), elimination of the functional groups accompanied in the conventional catalytic reduction process is also a difficult problem to be solved. Therefore, how to realize the efficient selective reduction of the nitroaromatic into the corresponding aniline product has important theoretical significance and has important practical application value.
The semiconductor photocatalytic reduction is a promising method for solving the technical bottleneck of traditional thermal catalysis in nitroarene reduction, is an environment-friendly technology, does not depend on harsh reaction conditions such as high hydrogen pressure, organic solvent, high temperature and the like during nitroarene reduction, has few side reactions and presents high-efficiency conversion rate and selectivity, particularly, the photocatalytic technology only depends on sunlight to drive chemical reaction, and does not bring new secondary pollution, is considered to be the most ideal and promising catalytic reduction technology (C.Hao, et al, visible light-drive selective catalytic reduction technology Au/SiCaalysts.J.Am.Chem.Soc.2016, 138,9361-9364), and also becomes the research hotspot and focus point of current nitroarene reduction, for example L Zhang et al prepares a nanowire titanium dioxide and graphene and carbon nitride three-dimensional composite photocatalyst, utilizes the photocatalytic reaction to achieve the photocatalytic reaction in nitrobenzene solvent conversion rate, such as 97% conversion rate of benzene in the solvent, L% of methanol, and 3578. Zhang et al2/g-C3N4G photocatalysts with extended spectral responses selective reduction of nitro-benzone.Appl.Catal.B: environ.2016,203, 1-8). Tsutsumi et al supported metal on semiconductor silicon, and studied the selective transformation law of solvent system p-nitrobenzene, found that when isopropanol is used as solvent, the reaction is in visible light (lambda)>400nm) and nitrobenzene selectivity decreased to about 94% with water, while only 83% (k.tsutsutsumi, et al, phosphor induced reduction of nitro-olefins using a conversion-metal L loaded silicon semiconductor unit visible light radiation. acs ca. 2016,6, 4394-.
Extensive literature research has revealed that the prior photocatalytic hydrogenation of nitroarenes still relies heavily on organic solvents to achieve efficient Reduction of monofunctional nitrobenzene, and apparently, when the nitroarenes containing multiple reactive groups are subjected to photocatalytic hydrogenation, more byproducts are necessarily produced, thereby severely reducing the conversion and selectivity of the hydrogenated nitroarenes (M.Shen, et al, Room-temperature chemical Reduction of 3-nitrostyrene to 3-vinylaniline by ammonium means of Borane over Cu nanoparticles, J.am.chem.Soc.2018,140, 16460-16463). For this reason, researchers have made a great deal of remarkable efforts to suppress the production of by-products, and have found that noble metals have strong adsorption properties to nitro groups, resulting in their good ability to reduce nitroarenes by photocatalytic hydrogenation. For example, Y.Song et al supported gold and platinum bimetallic on single-layer titanium dioxide nano-sheets, which were found to increase the chemoselectivity to halonitrobenzene to 87% -99% in methanol solvent under light irradiation (. lamda. <800nm) (Y.Song, et al, selective photocatalytic synthesis of halonitrobenzene from halonitrobenzene in organic phase ACS Catal.2018,8, 9656-. Hao et al supported noble metals gold and palladium on a silicon carbide semiconductor to prepare a bimetallic modified silicon carbide photocatalyst, and researches prove that the catalyst takes ethanol as a solvent and can effectively and selectively reduce p-nitrobenzaldehyde into p-aminobenzaldehyde under the action of introduced hydrogen so as to improve the conversion rate of the p-nitrobenzaldehyde to 98% (C.Hao, et al, synthetic effect of segmented Pd and Au nanoparticles on segmented SiC for electronic catalytic hydrogenation of nitro-olefins, Appacs.Mater.interface.2018, 10,23029 and 23036).
Although the noble metal modified photocatalyst can realize high-efficiency selective hydrogenation reduction on multi-functional nitroarene, the high cost and the dependence on organic solvents still limit the further application of the noble metal modified photocatalyst. To this end, W.Gao et al reported a Ni2Photocatalyst of P/CdS in pure water system and visible light (lambda)>420nm) to obtain p-chloroaniline (98%) (W.Gao et al, high selectivity and electrically catalytic reduction of Ni2P/CdS catalyst visible-light irradiation. chem. Commun.2015,51, 13217-. But furtherResearch shows that the conversion rate and the yield of the nitro aromatic hydrocarbon of the existing catalyst in a water system can not be converted efficiently (<98%). Therefore, a low-cost green and environment-friendly visible light catalyst is developed to realize the visible light (lambda) of the nitroaromatic hydrocarbon>420nm) and a water system, the technology of high-efficiency selective hydrogenation to corresponding aniline becomes the target of the research and development workers.
Disclosure of Invention
The invention aims to find a visible-light-driven photocatalyst which is simple to prepare, low in cost and excellent in performance, and can realize the efficient selective hydrogenation of nitroaromatic into corresponding aniline in a water system under the action of visible light, so as to solve the technical problem that the prior photocatalyst cannot realize the efficient selective hydrogenation of nitroaromatic into corresponding aniline in the action of visible light and a pure water system.
Strong visible light absorption and high efficiency of photo-generated electron-hole separation, which are two decisive factors for realizing high efficiency and selectivity of hydrogenation of nitroarenes by photocatalyst (Y. Chao et al, ultra In visible-light-drive organic hydrogenation In2O3-ZnIn2Se4Z-scheme nanoshiet photosatalysts, adv. mater.2019,31,1807226). Among semiconductor materials, cuprous oxide is considered a very promising photocatalytic material (t.wang, et al, homogeneous Cu) due to its non-toxicity, low cost and narrow band gap (2.0-2.2eV)2O p-n junctionphotocathodes for solar water splitting.appl.Catal.B. environ.2017,226,31-37), especially copper can also have good adsorption performance on nitro groups, and presents efficient selective reduction of nitroarenes. However, the existing preparation technology of the photocatalyst usually loads cuprous oxide on the surface of the carrier, and the activity is reduced due to aggregation and falling off of particles. On the other hand, silica is widely used as a support material for metal catalysts (S.Cao, et al, metal nanoparticles defined in the nanoparticles of double-shelled porous silicon catalysts for high-purity effective and electrically conductive catalyst, Chem.Mater.2016,28,5596-The optical property makes it an ideal photocatalyst carrier material. If cuprous oxide is combined with silicon dioxide and limited, the problems of agglomeration and falling off of cuprous oxide particles in the catalytic process can be effectively inhibited, so that the photo-generated electron efficiency is improved, and the aim of efficient selective reduction of the nitroarene is fulfilled.
The invention aims to prepare a high-efficiency stable visible-light-driven photocatalyst which is used for realizing the purpose of efficiently and selectively reducing nitroaromatic into corresponding aniline so as to solve the technical problem that the prior photocatalyst can not realize the efficient and selective reduction of the nitroaromatic in a visible light and pure water system.
In order to realize the purpose of the invention, the invention comprises the following key steps to prepare the hierarchical hollow silica limited cuprous oxide visible light catalyst:
(1) preparation of Cationic Polystyrene (CPS) template: adding styrene, deionized water, potassium persulfate and methacryloyloxyethyl trimethyl ammonium chloride into a four-neck flask, introducing nitrogen, and reacting at a certain temperature to obtain a Cationic Polystyrene (CPS) template.
(2)CPS@SiO2The preparation of (1): filtering and washing the CPS template prepared in the step (1), dissolving the washed CPS template in ethanol, adding the solution into a three-neck flask, adding a certain amount of ammonia water, adding tetraethyl orthosilicate, and reacting at a constant temperature to obtain CPS @ SiO2。
(3) And (3) adsorbing copper ions: taking the CPS @ SiO prepared in the step (2)2Dissolving in ethanol, mixing with copper nitrate water solution, stirring, and evaporating at certain temperature;
(4)CPS@SiO2-Cu2+@SiO2: dispersing the sample obtained in the step (3) in ethanol, pouring the mixture into a three-neck flask, adding a certain amount of ammonia water and tetraethyl orthosilicate, and reacting at constant temperature to obtain CPS @ SiO2-Cu2+@SiO2。
(5) Reduction: calcining the sample obtained in the step (4) to remove the CPS template, and then placing the sample in a tube furnace in Ar/H2Reducing the product in the atmosphere to obtain the hierarchical hollow silica confinement cuprous oxideAnd (4) visible light catalyst.
Preferably, in the step (1), the dosage ratio of the styrene to the deionized water to the potassium persulfate to the methacryloyloxyethyl trimethyl ammonium chloride is 7.5g to 72m L to 0.016 to 0.017g to 1.1g, the certain temperature is 70 ℃, and the reaction time is 8 to 12 hours.
Preferably, in step (2), 2g of CPS template is weighed, 3m of L ammonia water and 1.2g of tetraethyl orthosilicate are added, and the reaction temperature is 50 ℃ at constant temperature and the reaction time is 4-6 h.
Preferably, in step (3), the CPS @ SiO2The dosage ratio of the ethanol to the copper nitrate to the water is 2g to 20m L to 400mg to 20m L, and the certain temperature is 60 ℃.
Preferably, in the step (4), the amount of the ammonia water is 3m L, the amount of the tetraethyl orthosilicate added is 1.5g, the constant temperature is 50 ℃, and the reaction time is 4-6 h.
Preferably, in the step (5), the calcining temperature is 450-500 ℃, and the calcining time is 2-4 h; the reduction temperature is 300-400 ℃, and the reaction time is 2-4 h. Ar/H2In an atmosphere of Ar and H2Is 19: 1.
According to the preparation method of the hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalyst, the success of the preparation is determined by the following three key factors: firstly, preparing a cation polystyrene template; second is how to locate in SiO2Uniformly loading copper thereon; and thirdly how to reduce the copper oxide to cuprous oxide by calcination.
The invention uses deionized water as a solvent system; styrene is a monomer; potassium persulfate is taken as an initiator; methacryloyloxyethyl trimethyl ammonium chloride is used as a cationic modifier; tetraethyl orthosilicate is SiO2A precursor of (a); copper nitrate is the copper source.
The invention relates to a preparation method of a hierarchical hollow silica confinement cuprous oxide visible light catalyst, which is characterized in that a CPS template is prepared by referring to the previous invention patent (Chinese invention patent: Z L200910234354.1).
The invention relates to a preparation method of a hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalystMethod characterized by CPS @ SiO2The carrier is a core-shell structure formed by using CPS as a template and promoting tetraethyl orthosilicate to self-assemble on the surface of the CPS template through electrostatic acting force.
The invention discloses a preparation method of a hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalyst, which is characterized in that a semiconductor Cu is adopted2O is that copper particles are loaded on CPS @ SiO in an adsorption mode2On the surface, water and ethanol are then removed by evaporation to obtain a uniform copper particle loading, on the basis of which the SiO is coated2Outer layer of CPS @ SiO2-Cu2+@SiO2Sandwich structure, high-temp calcining to remove CPS template, and regulating temp in Ar/H2And reducing the copper oxide into cuprous oxide under the atmosphere.
The method comprises the steps of regulating and controlling a calcination program, heating to 450-500 ℃ at a heating rate of 2 ℃/min by using a 1100-type 304 calcining furnace from Haoyue corporation, continuously calcining for 2-4H, naturally cooling to room temperature, and placing the calcined product in a tube furnace in Ar/H2(19:1) reducing the mixture for 2 to 4 hours at the temperature of between 300 and 400 ℃ in the atmosphere to obtain SiO2-Cu2O@SiO2A photocatalyst.
Styrene used in the invention is a product of chemical reagents of national medicine group
The tetraethyl orthosilicate used in the invention is a product of chemical reagents of national drug group Limited.
The copper nitrate used in the invention is pentahydrate copper nitrate, is analytically pure, and is a product of chemical reagents of national medicine group limited company.
The ethanol used in the invention is analytically pure and is a product of chemical reagents of national drug group, Inc.
Compared with the existing photocatalyst, the photocatalyst has the following outstanding advantages:
(1) the invention combines the photocatalyst and the confinement effect for the first time to prepare the confinement type visible-light-driven photocatalyst, which is beneficial to the longer time of the incident light in the catalyst and improves the light quantum yield.
(2) The invention utilizes double-layer SiO2As a limitThe domain carrier can maximally utilize the excellent light transmittance and reduce the absorption of incident light.
(3) The invention settles the silicon dioxide by a template method, and the obtained SiO2The particle size and the shell thickness of the microspheres are uniform.
(4) The invention improves the content of copper ions in SiO by a solution distillation method instead of the traditional ion adsorption method2Uniformly dispersing the surface of the microsphere, namely mixing copper nitrate solution and SiO2The microspheres are prepared into a solution, mixed, stirred and adsorbed, and then slowly evaporated to dryness under stirring (300ppm) and a constant-temperature water bath (60 ℃) so as to ensure the maximum loading of copper ions.
(5) The invention relates to a limited-area visible light catalyst, which is characterized in that SiO with high light transmittance is utilized2The outer layer carries out 'packaging' on the cuprous oxide, can effectively reduce the problems of falling and aggregation of the cuprous oxide in the photocatalysis process, and improves the photon yield.
(6) The invention utilizes cationic CPS, which not only acts as ordered SiO2The template and small molecules generated by CPS in the calcination process are utilized to prepare the porous hollow SiO2And the carrier provides a channel for the catalyst and the catalytic substrate, and reduces the diffusion limitation of reactants and products.
(7) The invention utilizes segmented program calcination, namely, CPS templates are firstly removed by calcination in the air, the temperature is raised to 500 ℃ at the heating rate of 4 ℃/min, the CPS templates are continuously calcined for 2 hours, and the CPS templates are placed in a tube furnace after being naturally cooled to room temperature and then are placed in Ar/H2Heating to 400 ℃ at the heating rate of 4 ℃/min in the atmosphere for reduction to obtain SiO2-Cu2O@SiO2A photocatalyst.
Drawings
FIG. 1 is a hierarchical hollow silica-confined cuprous oxide visible light catalyst (SiO) prepared in example 12-Cu2O@SiO2Photocatalyst) SEM pictures.
FIG. 2 is a hierarchical hollow silica-confined cuprous oxide visible light catalyst (SiO) prepared in example 12-Cu2O@SiO2Photocatalyst) TEM pictures.
FIG. 3 is a hierarchical hollow dioxygen prepared in example 1Silicon-limited cuprous oxide visible-light-driven photocatalyst (SiO)2-Cu2O@SiO2Photocatalyst) under the irradiation of visible light, the effect diagram of catalytic reduction o-chloronitrobenzene.
FIG. 4 is a hierarchical hollow silica limited cuprous oxide visible light catalyst (SiO) prepared in example 12-Cu2O@SiO2Photocatalyst) under the irradiation of visible light, the effect diagram of catalytic reduction of 3-nitrostyrene.
Detailed Description
The following examples are further illustrative of the present invention and are not intended to limit the scope of the present invention.
Example 1:
(1) preparing a cationic template CPS, namely building an experimental device, introducing nitrogen into the system, adding 72m L water into a four-necked flask, heating a water bath kettle to 70 ℃, sequentially adding 0.16g of initiator and 7.5g of styrene, starting stirring and reacting for 1.5h, then adding a modifier of methacryloyloxyethyl trimethylammonium chloride aqueous solution, injecting two needles every half an hour (10 mu l per needle) for the first three needles, injecting one needle every hour (50 mu l) for each needle, then injecting one needle every 3 minutes for the rest solution, wherein each needle is 10 mu l until all the remaining methacryloyloxyethyl trimethylammonium chloride (DMC) is injected, injecting a mixed solution of 1.1g of methacryloyloxyethyl trimethylammonium chloride and 1.2g of deionized water by using a needle, prolonging the polymerization for 12 hours after the injection is completed, fully polymerizing the mixed solution, and finally preparing a 15% monodisperse cationic filter membrane by suction filtration, wherein the mass ratio of the polystyrene DMC is 15% that of the methacryloyloxyethyl trimethylammonium chloride is reduced to that of styrene;
(2)CPS@SiO2the preparation method comprises the steps of firstly carrying out suction filtration and washing on the CPS template prepared in the step (1), then drying, weighing 2g of sample, dispersing in 50m L ethanol, adding into a three-neck flask, adding 3m L ammonia water, and finally adding 1.2g of tetraethyl orthosilicate to react for 6h at constant temperature of 50 ℃.
(3) And (3) adsorbing copper ions: taking the CPS @ SiO prepared in the step (2)2Sample DispersionMixing with 20m L of copper nitrate aqueous solution in 20m L of ethanol, magnetically stirring for 12h, and evaporating to dryness at the constant temperature of 60 ℃ in a water bath kettle;
(4) preparation of CPS @ SiO2-Cu2+@SiO2Dissolving the sample obtained in the step (3) in 50m L ethanol, adding 3m L ammonia into a three-neck flask with the diameter of 100m L, and finally adding 1.5g tetraethyl orthosilicate for reacting for 4-6h at 50 ℃.
(5) Reduction: putting the sample obtained in the step (4) into an atmosphere furnace, heating to 500 ℃ at the heating rate of 4 ℃/min, continuously calcining for 2H to remove the CPS template, then putting the sample into a tube furnace, and putting the sample into Ar/H2(19:1) heating to 400 ℃ at the heating rate of 5 ℃/min under the atmosphere, and continuously calcining for 2h for reduction.
SiO as prepared in example 12-Cu2O@SiO2Carrying out application test on the photocatalyst;
example 2:
SiO2-Cu2O@SiO2the photocatalyst is used for reducing o-chloronitrobenzene;
the prepared o-chloronitrobenzene deionized water solution 20m L (1mg/m L) is poured into a reactor, 25mg of catalyst and 27mg of formic acid are added, then the photocatalytic behavior of the o-chloronitrobenzene is researched under the action of visible light, sampling is carried out every 30 minutes, a high performance liquid chromatograph is used for analysis, so that the reduction change of the o-chloronitrobenzene in different reduction time is obtained, and finally the conversion rate and the selectivity of the o-chloronitrobenzene are calculated according to the obtained data.
Example 3:
SiO2-Cu2O@SiO2the photocatalyst is used for reducing o-chloronitrobenzene;
the prepared o-chloronitrobenzene deionized water solution is poured into a reactor at the concentration of 40m L (1mg/m L), 25mg of catalyst and 54mg of formic acid are added, then the photocatalytic behavior of the o-chloronitrobenzene is researched under the action of visible light, sampling is carried out every 30 minutes, a high performance liquid chromatograph is used for analysis, so that the reduction change of the o-chloronitrobenzene at different reduction times is obtained, and finally the conversion rate and the selectivity of the o-chloronitrobenzene are calculated according to the obtained data.
Example 4:
SiO2-Cu2O@SiO23-nitrostyrene is reduced by the photocatalyst;
the prepared 3-nitrostyrene deionized water solution 20m L (0.2mg/m L) is poured into a reactor, 25mg of catalyst and 5.4mg of formic acid are added, then the photocatalytic behavior of the 3-nitrostyrene deionized water solution is researched under the action of visible light, sampling is carried out every 30 minutes, a high performance liquid chromatograph is used for analysis to obtain the reduction change of the o-chloronitrobenzene in different reduction times, and finally the conversion rate and the selectivity of the o-chloronitrobenzene are calculated according to the obtained data.
Example 5:
SiO2-Cu2O@SiO23-nitrostyrene is reduced by the photocatalyst;
the prepared 3-nitrostyrene deionized water solution 40m L (0.2mg/m L) is poured into a reactor, 25mg of catalyst and 10.8mg of formic acid are added, then the photocatalytic behavior of the 3-nitrostyrene deionized water solution is researched under the action of visible light, sampling is carried out every 30 minutes, a high performance liquid chromatograph is used for analysis, so that the reduction change of the o-chloronitrobenzene in different reduction times is obtained, and finally the conversion rate and the selectivity of the o-chloronitrobenzene are calculated according to the obtained data.
FIG. 1 is SiO as prepared in example 12-Cu2O@SiO2The shape of the complete sphere of the photocatalyst can be seen through the SEM picture of the photocatalyst;
FIG. 2 is SiO as prepared in example 12-Cu2O@SiO2TEM pictures of the photocatalyst; the porous structure of the catalyst can be seen by the pictures;
FIG. 3 is SiO as prepared in example 12-Cu2O@SiO2The photocatalyst reduces the o-chlorine under the irradiation of visible lightEffect diagram of nitrobenzene; the conversion rate reaches 99 percent, the selectivity reaches 100 percent, and the prepared catalyst can completely reduce o-chloronitrobenzene into o-chloroaniline by utilizing visible light in pure water;
FIG. 4 is SiO as prepared in example 12-Cu2O@SiO2The effect diagram of 3-nitrostyrene is reduced by the photocatalyst under the irradiation of visible light; the conversion rate reaches 98 percent, the selectivity reaches 100 percent, and the prepared catalyst can completely reduce 3-nitrostyrene into 3-aminostyrene by utilizing visible light in pure water;
description of the drawings: the above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; thus, while the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted; all such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.

Claims (7)

1. The preparation method of the hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalyst is characterized by comprising the following specific steps of:
(1) preparation of Cationic Polystyrene (CPS) template: adding styrene, deionized water, potassium persulfate and methacryloyloxyethyl trimethyl ammonium chloride into a four-neck flask, introducing nitrogen, and reacting at a certain temperature to obtain a Cationic Polystyrene (CPS) template;
(2)CPS@SiO2the preparation of (1): filtering and washing the CPS template prepared in the step (1), dissolving the washed CPS template in ethanol, adding the solution into a three-neck flask, adding a certain amount of ammonia water, adding tetraethyl orthosilicate, and reacting at a constant temperature to obtain CPS @ SiO2；
(3) And (3) adsorbing copper ions: taking the CPS @ SiO prepared in the step (2)2Dissolving in ethanol, mixing with copper nitrate water solution, stirring, and evaporating at certain temperature;
(4)CPS@SiO2-Cu2+@SiO2: subjecting the product obtained in step (3)Dispersing the sample in ethanol, pouring the sample into a three-neck flask, adding a certain amount of ammonia water and tetraethyl orthosilicate, and reacting at constant temperature to obtain CPS @ SiO2-Cu2+@SiO2；
(5) Reduction: calcining the sample obtained in the step (4) to remove the CPS template, and then placing the sample in a tube furnace in Ar/H2And reducing under the atmosphere to obtain the hierarchical hollow silica confinement cuprous oxide visible-light-driven photocatalyst.
2. The preparation method of the hierarchical hollow silica-restricted cuprous oxide visible light catalyst according to claim 1, wherein in step (1), the dosage ratio of styrene, deionized water, potassium persulfate and methacryloyloxyethyl trimethyl ammonium chloride is 7.5 g: 72m L: 0.016-0.017 g: 1.1g, the reaction time is 8-12h at a certain temperature of 70 ℃.
3. The preparation method of the graded hollow silica limited-area cuprous oxide visible-light-driven photocatalyst as claimed in claim 1, wherein in step (2), 2g of CPS template is weighed, 3m L of ammonia water and 1.2g of tetraethyl orthosilicate are added, the reaction temperature is 50 ℃ at constant temperature, and the reaction time is 4-6 h.
4. The method for preparing a graded hollow silica-confined cuprous oxide visible light catalyst as claimed in claim 1, wherein in step (3), said CPS @ SiO is2The dosage ratio of the ethanol to the copper nitrate to the water is 2g to 20m L to 400mg to 20m L, and the certain temperature is 60 ℃.
5. The preparation method of the graded hollow silica limited-area cuprous oxide visible light catalyst according to claim 1, wherein in step (4), the amount of ammonia water is 3m L, the amount of tetraethyl orthosilicate is 1.5g, the constant temperature is 50 ℃, and the reaction time is 4-6 h.
6. Preparation method of graded hollow silica limited-area cuprous oxide visible-light-driven photocatalyst according to claim 1The method is characterized in that in the step (5), the calcining temperature is 450-500 ℃, and the calcining time is 2-4 h; the reduction temperature is 300-400 ℃, and the reaction time is 2-4 h; Ar/H2In an atmosphere of Ar and H2Is 19: 1.
7. The use of the hierarchical hollow silica-confined cuprous oxide visible light catalyst prepared by the preparation method of any of claims 1-6, characterized in that: under the action of visible light, the method is used for efficiently and selectively hydrogenating nitroarene into corresponding aniline in a water system.
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