CN118022752A - Preparation method and application of sub-nano level monodisperse copper cerium oxide catalyst - Google Patents

Preparation method and application of sub-nano level monodisperse copper cerium oxide catalyst Download PDF

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CN118022752A
CN118022752A CN202311801570.6A CN202311801570A CN118022752A CN 118022752 A CN118022752 A CN 118022752A CN 202311801570 A CN202311801570 A CN 202311801570A CN 118022752 A CN118022752 A CN 118022752A
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copper
cerium
cerium oxide
nano
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夏怡
韩昌报
马铁军
郝明阳
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Beijing University of Technology
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Beijing University of Technology
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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
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/83—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
    • C—CHEMISTRY; METALLURGY
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/40—Carbon monoxide
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
    • C07C1/02—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides

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Abstract

A preparation method and application of a sub-nano level monodisperse copper cerium oxide catalyst, belonging to the field of catalysis. The liquid phase medium comprises sub-nano-scale copper cerium oxide particles; the sub-nano copper cerium oxide is that copper elements are uniformly distributed in cerium dioxide particles, the surface of the copper cerium oxide particles is wrapped with a surfactant layer, and the sub-nano copper cerium oxide particles wrapped with the surfactant layer are uniformly dispersed in a liquid phase medium to form a transparent dispersion. The solid content of the dispersion is 0.005wt.% to 60wt.%, the particle size of the copper cerium oxide crystal is sub-nanometer, and the one-dimensional size is 0.5nm to 3nm; the particle size distribution is uniform, and the monodispersity is achieved; the product has high purity and high stability, and is transparent and sedimentation-free (brown transparent dispersion) after standing for more than or equal to 24 months. The transparent dispersion of the copper cerium oxide of sub-nanometer level can be uniformly and firmly loaded on a carrier or directly used for photocatalytic carbon dioxide reduction in the form of dispersion liquid.

Description

Preparation method and application of sub-nano level monodisperse copper cerium oxide catalyst
Technical Field
The invention relates to the technical field of nano catalysts; more particularly, it relates to a method for preparing a sub-nano level monodisperse copper cerium oxide catalyst and application thereof in photocatalytic carbon dioxide reduction.
Background
The solar-driven photocatalytic carbon dioxide reduction is hopeful to relieve the greenhouse effect and the consumption of fossil energy, and is beneficial to realizing the carbon-to-carbon peak neutralization target. Due to its complex reduction pathway, the photo-reduced products of carbon dioxide include carbon monoxide, methanol, methane, formaldehyde, formic acid, and multi-carbon molecules such as ethane, ethylene, ethanol, acetic acid, etc. Among these hydrocarbons, methane is an important clean fuel that can be used as an industrial feedstock for the production of carbon black, H 2, chloroform and other valuable chemicals. Although reduction of carbon dioxide to methane is more advantageous than formation of CO and methanol in terms of reduction potential, this process is more kinetically difficult because it requires transfer of 8 electrons in combination with multiple protons. In addition, the complex proton-electron transfer pathway readily diverges to form other unwanted products, greatly impeding the activity and selectivity of the photoreduction of carbon dioxide to methane.
Ceria has two stable oxidation states, ce 2O3(Ce3+) and CeO 2(Ce4+), ceO 2 forms Ce 2O3 in an oxygen deficient environment while generating oxygen vacancies, and recovers in an oxygen rich environment. The redox character of Ce 3+/Ce4+ gives ceria a good oxygen storage capacity and is therefore widely used in the catalytic field. The sub-nanoscale ceria can provide an ultra-high proportion of surface-coordinated unsaturated Ce atoms, which can serve as active sites to generate active intermediates, contributing to an increase in the conversion of carbon dioxide to methane. In addition, positively charged copper-doped ceria can stabilize the ceria cubic fluorite structure, further improve the oxygen storage effect thereof, and promote the selective photocatalytic reduction of carbon dioxide to methane. The surface-well-modified sub-nano copper cerium oxide can be dispersed in a liquid phase medium in a transparent way, so that the catalyst can be uniformly loaded in a carrier, and the active center is highly dispersed and uniform, so that the catalyst has the advantages of easy separation and recovery while retaining high selectivity and activity in a reaction system.
The prior art discloses the preparation of cerium oxide nanoparticles, for example: chinese patent CN116966911a discloses a method for preparing a trivalent rare earth doped ceria supported metal catalyst, which is to add trivalent rare earth salt into cerium salt, make trivalent rare earth doped ceria obtain trivalent rare earth doped ceria, load a precursor of the metal catalyst onto the surface of the trivalent rare earth doped ceria, and calcine once. The existing defects of the method are that: the trivalent rare earth doped cerium oxide nano rod with good crystallinity (the axial length is 50-100 nm and the radial length is 5-10 nm) can be prepared through a calcination process, so that the prepared cerium oxide nano particles are easy to agglomerate and difficult to disperse.
Disclosure of Invention
The first technical problem to be solved by the present invention is to provide a sub-nano level monodisperse copper cerium oxide catalyst. The sub-nano level monodisperse copper cerium oxide catalyst prepared by the invention is characterized in that sub-nano level copper cerium oxide particles are extremely easy to disperse in a liquid phase medium, and the solid content is 0.005wt.% to 60wt.%; the particle size of the copper cerium oxide particles is extremely small, and the one-dimensional size is 0.5-3 nm; the method has the advantages of monodispersity, uniform particle size distribution and good dispersibility; the product has high transmittance, high purity and high stability, and is transparent and has no sedimentation after standing for more than or equal to 24 months.
In order to solve the first technical problem, the invention adopts the following technical scheme:
a sub-nano-scale monodisperse copper-cerium oxide catalyst dispersion, sub-nano-scale monodisperse copper-cerium oxide particles and a liquid phase medium; the sub-nano-scale copper cerium oxide is characterized in that copper elements are uniformly distributed and doped in cerium dioxide particles, the surface of the sub-nano-scale monodisperse copper cerium oxide particles is coated with a surface modifier layer, and nano cerium dioxide particles coated with the surface modifier layer are uniformly dispersed in a liquid phase medium to form transparent dispersoids.
Preferably, the solid content of the sub-nano-scale copper cerium oxide in the transparent dispersion is 0.005wt.% to 60wt.%, and the one-dimensional size of the sub-nano-scale copper cerium oxide particles is 0.5nm to 3nm.
Preferably, the surface modifier layer comprises one or more of the following: n-butyric acid, n-caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, oleylamine, sodium oleate, sodium laurate, sodium stearate, [3- (methacryloyloxy) propyl ] trimethoxysilane (KH 570), gamma-glycidoxypropyl trimethoxysilane (KH 560), (3-aminopropyl) triethoxysilane (KH 550), (3-mercaptopropyl) trimethoxysilane, sodium dodecyl sulfate, cetyl ammonium bromide, tween-80, polyethylene glycol-200, polyethylene glycol-4000, polyethylene glycol-10000, trimethyloxonium tetrafluoroborate, triethyloxotetrafluoroborate, nitrotetrafluoroborate, tribenzyl carbonium tetrafluoroborate, ammonium fluoroborate.
Preferably, the liquid phase medium comprises one or more of the following: formamide, N-dimethylformamide, methanol, ethanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, toluene, benzene, benzyl alcohol, cyclohexane, N-hexane, N-heptane, petroleum ether (30-60 ℃), petroleum ether (60-90 ℃), methylene chloride, chloroform, white oil, naphtha, castor oil, diesel oil, methyl isobutyl ketone, methyl methacrylate, 3-phenoxybenzyl acrylate.
In order to solve the second technical problem, the preparation method of the sub-nano monodisperse copper cerium oxide catalyst dispersion liquid comprises the following steps:
1) Adding a cerium source into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a cerium source solution;
2) Taking water, an organic solvent or a mixture of water and the organic solvent as a solvent, and adding an alkali source into the solvent to prepare an alkali source solution;
3) Adding a surface modifier into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a surface modifier solution;
4) Mixing the cerium source solution in the step 1) and the alkali source solution in the step 2), and continuing to react after mixing;
5) Mixing the surface modifier solution with the mixture obtained in the step 4), continuing the modification reaction after mixing, carrying out solid-liquid separation after the reaction, and washing and drying the separated cerium dioxide solid;
6) Taking water, an organic solvent or a mixture of water and the organic solvent as a disperse phase, and washing and drying the cerium dioxide solid to be transparent dispersed in the disperse phase to obtain a cerium dioxide transparent dispersion;
7) Adding a copper source into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a copper source solution;
8) Mixing the cerium dioxide transparent dispersion in the step 6) with the copper source solution in the step 7), performing solvothermal reaction, performing solid-liquid separation after the reaction, washing and drying the separated copper cerium oxide solid, and dispersing the washed and dried copper cerium oxide solid in a liquid phase medium to obtain a product of sub-nano monodisperse copper cerium oxide catalyst dispersion;
As a further improvement of the technical scheme, in step 1), the cerium source is selected from one or more of the following substances: the cerium source is selected from one or more of the following: cerium fluoride, cerium iodide, cerium bromide, anhydrous cerium sulfate, tetrahydrated cerium sulfate, anhydrous cerium chloride, heptahydrated cerium chloride, hexahydrated cerium nitrate, cerium oxalate hydrate, cerium (III) carbonate hydrate, cerium (III) acetate hydrate;
Preferably, in step 1), the organic solvent is selected from one or more of the following: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, dichloromethane, chloroform, N-dimethylformamide, dimethyl sulfoxide; the ratio of water to the organic solvent in the solvent is any ratio;
in step 1), the concentration of the cerium source solution is 0.01wt.% to 60 wt.%;
Preferably, in step 1), the concentration of the cerium source solution is 0.1wt.% to 50wt.%.
As a further improvement of the technical scheme, in the step 2), the alkali source is selected from one or more of the following substances: sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, triethylamine, and triethanolamine;
Preferably, in step 2), the organic solvent is selected from one or more of the following: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, methylene chloride, chloroform, N-dimethylformamide, dimethyl sulfoxide, methyl isobutyl ketone; the ratio of water to the organic solvent in the solvent is any ratio; the ratio of water to the organic solvent in the solvent is any ratio;
in step 2), the alkali source solution concentration is 0.1wt.% to 50wt.%;
preferably, in step 2), the concentration of the alkaline source solution is 0.5wt.% to 40wt.%.
As a further improvement of the technical scheme, in step 3), the surface modifier is selected from one or more of the following substances: n-butyric acid, n-caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, oleylamine, sodium oleate, sodium laurate, sodium stearate, [3- (methacryloyloxy) propyl ] trimethoxysilane (KH 570), gamma-glycidoxypropyl trimethoxysilane (KH 560), (3-aminopropyl) triethoxysilane (KH 550), (3-mercaptopropyl) trimethoxysilane, sodium dodecyl sulfate, cetyl ammonium bromide, tween-80, polyethylene glycol-200, polyethylene glycol-4000, polyethylene glycol-10000, trimethyloxonium tetrafluoroborate, triethyloxotetrafluoroborate, nitrotetrafluoroborate, tribenzyl carbonium tetrafluoroborate, ammonium fluoroborate;
Preferably, in step 3), the organic solvent is selected from one or more of the following: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, methylene chloride, chloroform, N-dimethylformamide, dimethyl sulfoxide, methyl isobutyl ketone; the ratio of water to the organic solvent in the solvent is any ratio;
in step 3), the surface modifier solution concentration is from 0.1wt.% to 80wt.%;
preferably, in step 3), the concentration of the surfactant solution is from 0.5wt.% to 40wt.%.
As a further improvement of the technical scheme, in the step 4), the mixing mode of the cerium source solution and the alkali source solution is as follows: adding a cerium source solution to an alkali source solution at a certain flow rate, or adding an alkali source solution to a cerium source solution at a certain flow rate; the flow rate is 0.01-100L/min/mol Ce element; the stirring speed is 200-800 r/min;
In the step 4), the reaction temperature is 10-150 ℃ and the reaction time is 0-3 h;
preferably, the reaction temperature is 15-95 ℃; the reaction time is 0-2.5 h.
As a further improvement of the technical scheme, in the step 5), the mixing mode of the mixture of the step 4) and the surfactant solution is as follows: adding a surface modifier solution to the mixture of step 4) at a flow rate; the flow rate is 0.03-90L/min/mol Ce element; the stirring speed is 200-800 r/min; the volume ratio of the mixture to the surfactant solution is 0.1-50:1;
The liquid medium used for washing is selected from one or more of the following: methanol, ethanol, isopropanol, toluene, cyclohexane, n-hexane, acetone, benzyl alcohol, tetrahydrofuran, methylene chloride, chloroform; washing is one or more of washing, filtering (suction filtration or press filtration, ultrafiltration, nanofiltration), dialysis and centrifugation; the washing times are 2 to 5 times; the drying mode is one or more of freeze drying, vacuum drying, normal pressure evaporating, rotary decompression evaporating, air blast drying, infrared irradiation and spray drying;
in the step 5), the modification reaction temperature is 10-180 ℃, and the modification reaction time is 15 min-6 h; the drying temperature is-10 to 150 ℃ and the drying time is 5min to 48h;
Preferably, in step 5), the modification reaction temperature is 10-80 ℃; the modification reaction time is 30 min-2.5 h; the drying temperature is between-5 and 120 ℃ and the drying time is between 5 minutes and 36 hours.
As a further improvement of the technical scheme, in step 6), the organic solvent is selected from one or more of the following substances: formamide, N-dimethylformamide, methanol, ethanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, toluene, benzene, benzyl alcohol, cyclohexane, N-hexane, N-heptane, petroleum ether (30-60 ℃), petroleum ether (60-90 ℃), methylene chloride, chloroform, white oil, naphtha, castor oil, diesel oil, methyl isobutyl ketone, methyl methacrylate, 3-phenoxybenzyl acrylate;
in step 6), the ceria dispersion obtained has a solids content of 0.005wt.% to 60wt.%;
preferably, the ceria dispersion obtained has a solids content of 0.5wt.% to 60wt.%.
As a further improvement of the technical solution, in step 7), the copper source is selected from one or more of the following: copper gluconate, copper acetylacetonate, copper fluoroborate, copper citrate, copper acetate monohydrate, copper isooctanoate, anhydrous copper acetate, basic copper carbonate, copper (II) tartrate hydrate, copper oxalate, copper acetate monohydrate, copper butyrate, copper stearate, anhydrous copper sulfate, copper sulfate pentahydrate, basic copper sulfate, anhydrous copper chloride, copper chloride dihydrate, copper nitrate trihydrate; the organic solvent is selected from one or more of the following substances: oleic acid, linoleic acid, oleylamine, methanol, ethanol, isopropanol, toluene, benzyl alcohol, cyclohexane, n-hexane, 1, 2-butanediol; the ratio of water to the organic solvent in the solvent is any ratio; the volume ratio of the copper source solution to the cerium source solution is 0.01-50: 1, a step of;
in step 7), the copper source solution concentration is 0.01wt.% to 20wt.%;
preferably, in step 7), the copper source solution has a concentration of 0.05wt.% to 18wt.%.
As a further improvement of the technical scheme, in the step 8), the mixing mode of the cerium oxide transparent dispersion and the copper source solution is as follows: adding the cerium oxide transparent dispersion to the copper source solution at a flow rate; the flow rate is 0.01-100L/min/mol Ce element; stirring speed is 0-800 r/min; the separation and washing mode is one or more of washing, filtering (suction filtration or filter pressing, ultrafiltration and nanofiltration), dialysis and centrifugation; the liquid medium used for washing is selected from one or more of the following: methanol, ethanol, isopropanol, toluene, cyclohexane, n-hexane, acetone, benzyl alcohol, tetrahydrofuran, methylene chloride, chloroform; the washing times are 2 to 5 times; the drying mode is one or more of freeze drying, vacuum drying, normal pressure evaporating, rotary decompression evaporating, air blast drying, infrared irradiation and spray drying; the liquid phase medium is selected from one or more of the following substances: formamide, N-dimethylformamide, methanol, ethanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, toluene, benzene, benzyl alcohol, cyclohexane, N-hexane, N-heptane, petroleum ether (30-60 ℃), petroleum ether (60-90 ℃), methylene chloride, chloroform, white oil, naphtha, castor oil, diesel oil, methyl isobutyl ketone, methyl methacrylate, 3-phenoxybenzyl acrylate;
In step 8), the cerium oxide and Cu in the copper source: the molar ratio of Ce is 0.0001-3: 1, a step of; the solvothermal reaction temperature is 80-260 ℃; the solvothermal time is 2-96 hours; the drying temperature is-10 to 150 ℃ and the drying time is 5min to 48h; the concentration of the obtained transparent dispersion of the sub-nano level monodisperse copper cerium oxide catalyst is 0.005wt.% to 60wt.%
Preferably, in step 8), the cerium oxide is mixed with Cu in the copper source: the molar ratio of Ce is 0.005-2.7: 1, a step of; the volume ratio of the copper source solution to the cerium source solution is 0.01-40: 1, a step of; the solvothermal reaction temperature is 120-250 ℃; the solvothermal time is 2-72 h; the drying temperature is between-5 and 120 ℃ and the drying time is between 5 minutes and 36 hours; the concentration of the obtained transparent dispersion of the sub-nano level monodisperse copper cerium oxide catalyst is 0.5wt.% to 60wt.%.
The third technical problem to be solved by the invention is to provide an application of a sub-nano level monodisperse copper cerium oxide catalyst as a photocatalytic carbon dioxide reduction catalyst; the photocatalytic carbon dioxide reduction system may use a gas-solid mode or a liquid-solid mode. The gas-solid mode is to load the prepared nano dispersion of the sub-nano monodisperse copper-cerium oxide catalyst on a carrier, remove a surfactant layer coated by the nano copper-cerium oxide catalyst by irradiation of an ultraviolet ozone light cleaner, take deionized water as a sacrificial agent, take carbon dioxide as a reactant, and carry out visible light irradiation reaction; the liquid-solid mode is that the nano dispersion of the sub-nano level monodisperse copper cerium oxide catalyst is directly added into a reaction system, a sacrificial agent is added, and carbon dioxide is taken as a reactant to carry out visible light irradiation reaction.
Preferably, the carrier in the gas-solid mode is one or more of ITO glass, FTO glass, common glass, hydrophilic carbon cloth and hydrophobic carbon cloth;
preferably, the loading mode in the gas-solid mode is one or more of infiltration, spin coating, blade coating and spray coating;
preferably, the photocatalytic carbon dioxide reduction product in the gas-solid mode is one or more of carbon monoxide, hydrogen, methane, ethylene and ethane;
preferably, the sacrificial agent in the liquid-solid mode is one or more of triethanolamine, triethylamine, N-dimethylformamide sodium sulfide, sodium sulfite and lactic acid;
Preferably, the photocatalytic carbon dioxide reduction product in the liquid-solid mode is one or more of carbon monoxide, hydrogen, methane, ethylene, ethane, formic acid, acetic acid, methanol and ethanol.
Any range recited in the invention includes any numerical value between the endpoints and any sub-range of any numerical value between the endpoints or any numerical value between the endpoints.
Unless otherwise indicated, all starting materials herein are commercially available, and the equipment used in the present invention may be conventional in the art or may be conventional in the art.
Compared with the prior art, the invention has the following beneficial effects:
The beneficial effects of the invention are as follows:
1) The sub-nano level monodisperse copper cerium oxide catalyst prepared by the invention is extremely easy to be transparent dispersed in a liquid phase solvent, and the solid content is 0.005wt.% to 60wt.%;
2) The grain diameter of the copper cerium oxide crystal is small, and the one-dimensional size is 0.5-3 nm; the method has the advantages of monodispersity, uniform particle size distribution and good dispersibility;
3) The product has high transmittance, high purity and high stability, and is transparent and has no sedimentation after standing for more than or equal to 6 months;
4) The product has good performance of photocatalytic reduction of carbon dioxide.
Drawings
The following describes the embodiments of the present invention in further detail with reference to the drawings
FIG. 1 is a photograph showing a cerium oxide obtained in step 6) of example 1 of the present invention;
FIG. 2 is a photograph showing a real object of the copper cerium oxide obtained in step 8) of example 1 of the present invention;
FIG. 3 shows a transmission electron micrograph and a corresponding particle size distribution plot of the copper cerium oxide obtained in step 8) of example 1 of the present invention;
FIG. 4 shows X-ray diffraction (XRD) patterns of cerium oxide obtained in step 6) and copper cerium oxide obtained in step 8) of example 1 according to the present invention;
FIG. 5 shows an X-ray energy spectrum (EDX) of the copper cerium oxide obtained in step 8) of example 1 of the present invention;
FIG. 6 is a diagram showing the embodiment of the invention (applicable to gas-solid mode and liquid-solid mode) of the device for photocatalytic reduction of carbon dioxide by the copper cerium oxide catalyst obtained in step 8);
Fig. 7 shows experimental results of photocatalytic carbon dioxide reduction of the copper cerium oxide obtained in example 1 of the present invention using a gas-solid method;
FIG. 8 is a photograph showing the cerium oxide obtained in step 6) of example 2 of the present invention;
FIG. 9 is a photograph showing a real object of the copper cerium oxide obtained in step 8) of example 2 of the present invention;
fig. 10 shows experimental results of photocatalytic carbon dioxide reduction using a liquid-solid method for the copper cerium oxide obtained in example 2 of the present invention;
FIG. 11 shows a transmission electron micrograph and corresponding physical image of the mixture of zirconium dioxide and cuprous oxide nanoparticles obtained in comparative example 2 of the present invention;
Detailed Description
In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.
As one aspect of the present invention, a sub-nano-scale monodisperse copper cerium oxide catalyst of the present invention comprises sub-nano-scale monodisperse copper cerium oxide particles and a liquid phase medium; the surface of the sub-nano monodisperse copper cerium oxide particles is coated with a surfactant layer, and the sub-nano monodisperse copper cerium oxide particles coated with the surfactant layer are uniformly dispersed in a liquid phase medium to form a transparent dispersion.
According to certain embodiments of the present invention, the solid content of the nano-ceria in the transparent dispersion is 0.005wt.% to 60wt.%, or 0.01wt.% to 60wt.%, or 0.02wt.% to 60wt.%, or 0.05wt.% to 60wt.%, or 0.1wt.% to 60wt.%, or 0.5wt.% to 60wt.%, or 1wt.% to 60wt.%, or 2wt.% to 60wt.%, or 5wt.% to 60wt.%, or 8wt.% to 60wt.%, or 10wt.% to 50wt.%, or 10wt.% to 45wt.%, or 10wt.% to 40wt.%, or 10wt.% to 35wt.%, or 10wt.% to 30wt.%, or 10wt.% to 25wt.%, or 10wt.% to 20wt.%, or 10wt.% to 15wt.%, or 15wt.% to 55wt.%, or 20wt.% to 50wt.%, or 25wt.%, and the one-dimensional monodisperse copper-based nano-ceria particles is 0 nm in a one-dimensional range of from 0 nm.
According to certain embodiments of the invention, the surfactant layer comprises one or more of the following: n-butyric acid, n-caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, oleylamine, sodium oleate, sodium laurate, sodium stearate, [3- (methacryloyloxy) propyl ] trimethoxysilane (KH 570), gamma-glycidoxypropyl trimethoxysilane (KH 560), (3-aminopropyl) triethoxysilane (KH 550), (3-mercaptopropyl) trimethoxysilane, sodium dodecyl sulfate, cetyl ammonium bromide, tween-80, polyethylene glycol-200, polyethylene glycol-4000, polyethylene glycol-10000, trimethyloxonium tetrafluoroborate, triethyloxotetrafluoroborate, nitrotetrafluoroborate, tribenzyl carbonium tetrafluoroborate, ammonium fluoroborate.
According to certain embodiments of the invention, the liquid phase medium comprises one or more of the following: formamide, N-dimethylformamide, methanol, ethanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, toluene, benzene, benzyl alcohol, cyclohexane, N-hexane, N-heptane, petroleum ether (30-60 ℃), petroleum ether (60-90 ℃), methylene chloride, chloroform, white oil, naphtha, castor oil, diesel oil, methyl isobutyl ketone, methyl methacrylate, 3-phenoxybenzyl acrylate.
As another aspect of the invention, the preparation method of the sub-nano level monodisperse copper cerium oxide catalyst comprises the following steps:
1) Adding a cerium source into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a cerium source solution;
2) Taking water, an organic solvent or a mixture of water and the organic solvent as a solvent, and adding an alkali source into the solvent to prepare an alkali source solution;
3) Adding a surface modifier into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a surface modifier solution;
4) Mixing cerium source solution and alkali source solution, and continuing to react after mixing;
5) Mixing the surface modifier solution with the mixture obtained in the step 4), continuing the modification reaction after mixing, carrying out solid-liquid separation after the reaction, and washing and drying the separated cerium dioxide solid;
6) Taking water, an organic solvent or a mixture of water and the organic solvent as a disperse phase, and washing and drying the cerium dioxide solid to be transparent dispersed in the disperse phase to obtain a cerium dioxide transparent dispersion;
7) Adding a copper source into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a copper source solution;
8) Mixing a cerium dioxide transparent dispersion with a copper source solution, performing solvothermal reaction, performing solid-liquid separation after the reaction, washing and drying the separated copper cerium oxide solid, and dispersing the washed and dried copper cerium oxide solid in a liquid phase solvent to obtain a product of the sub-nano monodisperse copper cerium oxide catalyst;
The preparation method provided by the invention prepares the sub-nano-level copper cerium oxide particles with monodisperse and particle size within the range of 0.5-3 nm, can be transparent and monodisperse in a liquid phase medium with extremely high solid content (0.005-60 wt.%), can exist stably for a long time, and is one of the copper cerium oxide particles with the smallest particle size in the current report; the prepared sub-nano copper cerium oxide particles can be well transparent and monodisperse in a liquid phase medium to form copper cerium oxide dispersion; the sub-nano level monodisperse copper cerium oxide catalyst nano dispersion is loaded on a carrier, and the surfactant layer coated by the nano copper cerium oxide catalyst is removed by irradiation of an ultraviolet ozone light cleaner, so that the catalyst has excellent photocatalysis.
According to certain embodiments of the invention, in step 1), the cerium source is selected from one or more of the following: the cerium source is selected from one or more of the following: cerium fluoride, cerium iodide, cerium bromide, anhydrous cerium sulfate, tetrahydrated cerium sulfate, anhydrous cerium chloride, heptahydrated cerium chloride, hexahydrated cerium nitrate, cerium oxalate hydrate, cerium (III) carbonate hydrate, cerium (III) acetate hydrate; the organic solvent is selected from one or more of the following substances: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, dichloromethane, chloroform, N-dimethylformamide, dimethyl sulfoxide; the ratio of water to the organic solvent in the solvent is any ratio;
in step 1), the concentration of the cerium source solution is 0.01wt.% to 60 wt.%;
Preferably, in step 1), the concentration of the cerium source solution is 0.1wt.% to 50wt.%.
According to certain embodiments of the invention, in step 2), the alkali source is selected from one or more of the following: sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, triethylamine, and triethanolamine; the organic solvent is selected from one or more of the following substances: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, methylene chloride, chloroform, N-dimethylformamide, dimethyl sulfoxide, methyl isobutyl ketone; the ratio of water to the organic solvent in the solvent is any ratio; the ratio of water to the organic solvent in the solvent is any ratio;
in step 2), the alkali source solution concentration is 0.1wt.% to 50wt.%; the volume ratio of the alkali source solution to the cerium source solution is 0.01-6: 1, a step of;
Preferably, in step 2), the concentration of the alkaline source solution is 0.5wt.% to 40wt.%; the volume ratio of the alkali source solution to the cerium source solution is 0.02-5: 1.
According to certain embodiments of the invention, in step 3), the surface modifying agent is selected from one or more of the following: n-butyric acid, n-caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, oleylamine, sodium oleate, sodium laurate, sodium stearate, [3- (methacryloyloxy) propyl ] trimethoxysilane (KH 570), gamma-glycidoxypropyl trimethoxysilane (KH 560), (3-aminopropyl) triethoxysilane (KH 550), (3-mercaptopropyl) trimethoxysilane, sodium dodecyl sulfate, cetyl ammonium bromide, tween-80, polyethylene glycol-200, polyethylene glycol-4000, polyethylene glycol-10000, trimethyloxonium tetrafluoroborate, triethyloxotetrafluoroborate, nitrotetrafluoroborate, tribenzyl carbonium tetrafluoroborate, ammonium fluoroborate; the organic solvent is selected from one or more of the following substances: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, methylene chloride, chloroform, N-dimethylformamide, dimethyl sulfoxide, methyl isobutyl ketone; the ratio of water to the organic solvent in the solvent is any ratio;
In step 3), the surface modifier solution concentration is from 0.1wt.% to 80wt.%; the volume ratio of the surface modifier solution to the cerium source solution is 0.001-50: 1, a step of;
preferably, in step 3), the concentration of the surfactant solution is from 0.5wt.% to 40wt.%; the volume ratio of the surface modifier solution to the cerium source solution is 0.001-45: 1.
According to certain embodiments of the present invention, in step 4), the cerium source solution and the alkali source solution are mixed in the following manner: adding a cerium source solution to an alkali source solution at a certain flow rate, or adding an alkali source solution to a cerium source solution at a certain flow rate; the flow rate is 0.01-100L/min/mol Ce element; the stirring speed is 200-800 r/min;
In the step 4), the reaction temperature is 10-150 ℃ and the reaction time is 0-3 h;
preferably, the reaction temperature is 15-95 ℃; the reaction time is 0-2.5 h.
According to certain embodiments of the present invention, in step 5), the mixture of step 4) and the surfactant solution are mixed in such a way that: adding a surface modifier solution to the mixture of step 4) at a flow rate; the flow rate is 0.03-90L/min/mol Ce element; the stirring speed is 200-800 r/min; washing is one or more of washing, filtering (suction filtration or press filtration, ultrafiltration, nanofiltration), dialysis and centrifugation; the liquid medium used for washing is selected from one or more of the following: methanol, ethanol, isopropanol, toluene, cyclohexane, n-hexane, acetone, benzyl alcohol, tetrahydrofuran, methylene chloride, chloroform; the washing times are 2 to 5 times; the drying mode is one or more of freeze drying, vacuum drying, normal pressure evaporating, rotary decompression evaporating, air blast drying, infrared irradiation and spray drying;
in the step 5), the modification reaction temperature is 10-180 ℃, and the modification reaction time is 15 min-6 h; the drying temperature is-10 to 150 ℃ and the drying time is 5min to 48h;
Preferably, in step 5), the modification reaction temperature is 10-80 ℃; the modification reaction time is 30 min-2.5 h; the drying temperature is between-5 and 120 ℃ and the drying time is between 5 minutes and 36 hours.
According to certain embodiments of the invention, in step 6), the organic solvent is selected from one or more of the following: formamide, N-dimethylformamide, methanol, ethanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, toluene, benzene, benzyl alcohol, cyclohexane, N-hexane, N-heptane, petroleum ether (30-60 ℃), petroleum ether (60-90 ℃), methylene chloride, chloroform, white oil, naphtha, castor oil, diesel oil, methyl isobutyl ketone, methyl methacrylate, 3-phenoxybenzyl acrylate;
in step 6), the ceria dispersion obtained has a solids content of 0.005wt.% to 60wt.%;
preferably, the ceria dispersion obtained has a solids content of 0.5wt.% to 60wt.%.
According to certain preferred embodiments of the present invention, in step 7), the copper source is selected from one or more of the following: copper gluconate, copper acetylacetonate, copper fluoroborate, copper citrate, copper acetate monohydrate, copper isooctanoate, anhydrous copper acetate, basic copper carbonate, copper (II) tartrate hydrate, copper oxalate, copper acetate monohydrate, copper butyrate, copper stearate, anhydrous copper sulfate, copper sulfate pentahydrate, basic copper sulfate, anhydrous copper chloride, copper chloride dihydrate, copper nitrate trihydrate; the organic solvent is selected from one or more of the following substances: oleic acid, linoleic acid, oleylamine, methanol, ethanol, isopropanol, toluene, benzyl alcohol, cyclohexane, n-hexane, 1, 2-butanediol; the ratio of water to the organic solvent in the solvent is any ratio;
in step 7), the copper source solution concentration is 0.01wt.% to 20wt.%;
preferably, in step 7), the copper source solution has a concentration of 0.05wt.% to 18wt.%.
According to certain preferred embodiments of the present invention, in step 8), the transparent dispersion of cerium oxide is mixed with the copper source solution in such a way that: adding the cerium oxide transparent dispersion to the copper source solution at a flow rate; the flow rate is 0.01-100L/min/mol Ce element; stirring speed is 0-800 r/min; the separation and washing mode is one or more of washing, filtering (suction filtration or filter pressing, ultrafiltration and nanofiltration), dialysis and centrifugation; the liquid medium used for washing is selected from one or more of the following: methanol, ethanol, isopropanol, toluene, cyclohexane, n-hexane, acetone, benzyl alcohol, tetrahydrofuran, methylene chloride, chloroform; the washing times are 2 to 5 times; the drying mode is one or more of freeze drying, vacuum drying, normal pressure evaporating, rotary decompression evaporating, air blast drying, infrared irradiation and spray drying; the liquid phase medium is selected from one or more of the following substances: formamide, N-dimethylformamide, methanol, ethanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, toluene, benzene, benzyl alcohol, cyclohexane, N-hexane, N-heptane, petroleum ether (30-60 ℃), petroleum ether (60-90 ℃), methylene chloride, chloroform, white oil, naphtha, castor oil, diesel oil, methyl isobutyl ketone, methyl methacrylate, 3-phenoxybenzyl acrylate;
In step 8), the cerium oxide and Cu in the copper source: the atomic ratio of Ce is 0.0001-3: 1, a step of; the solvothermal reaction temperature is 80-260 ℃; the solvothermal time is 2-96 hours; the drying temperature is-10 to 150 ℃ and the drying time is 5min to 48h; the concentration of the obtained transparent dispersion of the sub-nano level monodisperse copper cerium oxide catalyst is 0.005wt.% to 60wt.%
Preferably, in step 8), the cerium oxide is mixed with Cu in the copper source: the atomic ratio of Ce is 0.005-2.7: 1, a step of; the volume ratio of the copper source solution to the cerium source solution is 0.01-40: 1, a step of; the solvothermal reaction temperature is 120-250 ℃; the solvothermal time is 2-72 h; the drying temperature is between-5 and 120 ℃ and the drying time is between 5 minutes and 36 hours; the concentration of the obtained transparent dispersion of the sub-nano level monodisperse copper cerium oxide catalyst is 0.5wt.% to 60wt.%.
As a further aspect of the present invention, the use of the above-prepared sub-nano-scale monodisperse copper cerium oxide catalyst as a photocatalytic carbon dioxide reduction catalyst; the photocatalytic carbon dioxide reduction system may use a gas-solid mode or a liquid-solid mode. The gas-solid mode is to load the prepared nano dispersion of the sub-nano monodisperse copper-cerium oxide catalyst on a carrier, remove a surfactant layer coated by the nano copper-cerium oxide catalyst by irradiation of an ultraviolet ozone light cleaner, take deionized water as a sacrificial agent and take carbon dioxide as a reactant; the liquid-solid mode is that the nano dispersion of the sub-nano level monodisperse copper cerium oxide catalyst is directly added into a reaction system, a sacrificial agent is added, and carbon dioxide is used as a reactant.
Preferably, the carrier in the gas-solid mode is one or more of ITO glass, FTO glass, common glass, hydrophilic carbon cloth and hydrophobic carbon cloth;
preferably, the loading mode in the gas-solid mode is one or more of infiltration, spin coating, blade coating and spray coating;
preferably, the photocatalytic carbon dioxide reduction product in the gas-solid mode is one or more of carbon monoxide, hydrogen, methane, ethylene and ethane;
preferably, the sacrificial agent in the liquid-solid mode is one or more of triethanolamine, triethylamine, N-dimethylformamide sodium sulfide, sodium sulfite and lactic acid;
Preferably, the photocatalytic carbon dioxide reduction product in the liquid-solid mode is one or more of carbon monoxide, hydrogen, methane, ethylene, ethane, formic acid, acetic acid, methanol and ethanol.
The preparation process parameters of the invention form an organic integral technical scheme, thus obtaining the sub-nano level monodisperse copper cerium oxide catalyst with the solid content of 0.005wt.% to 60wt.%; the one-dimensional size is 0.5-3 nm, and the particles have the advantages of monodispersity, uniform particle size distribution, good dispersibility and no sedimentation after standing for more than or equal to 24 months.
Example 1
The preparation method of the sub-nano level monodisperse copper cerium oxide catalyst comprises the following steps:
1) 8.86g cerium sulfate tetrahydrate was dissolved in a mixture of 30mL dimethyl sulfoxide, 30mL ethanol and 60mL deionized water to prepare a cerium source solution;
2) 0.4mL of tetramethylammonium hydroxide was dissolved in a mixture of 45mL of ethylene glycol and 90mL of deionized water to prepare an alkaline source solution (volume ratio of alkaline source solution to cerium source solution: 1.2);
3) 4mL KH560 was dissolved in a mixture of 50mL ethanol and 50mL isopropanol to prepare a surface modifier solution (volume ratio of surface modifier solution to cerium source solution was 0.9);
4) Dropwise adding an alkali source solution into a cerium source solution through a advection pump, controlling the dropwise adding speed to be 4mL/min (0.18L/min/mol Ce element), reacting at 95 ℃, and stirring at a speed of 500r/min to obtain a reaction solution;
5) Dropwise adding a surfactant solution into the reaction solution obtained in the step 4) through a advection pump, controlling the dropwise adding speed to be 10mL/min (0.46L/min/mol Ce element), stirring the mixture at the speed of 500r/min, the modification reaction temperature to be 75 ℃, the modification reaction time to be 1h, separating cerium oxide solid through suction filtration after the modification reaction is finished, and performing suction filtration and washing for 4 times by taking ethanol as a liquid phase medium, wherein the drying temperature is 80 ℃ and the drying time is 4h;
6) Taking a mixture of 20mL of ethanol and 20mL of ethylene glycol as a disperse phase, wherein the cerium oxide solid prepared in the step 5) can be dispersed in the disperse phase in a transparent way to obtain an orange cerium oxide transparent dispersion, a physical diagram is shown in figure 1, and the solid content is 2 wt% (the volume ratio of the cerium oxide dispersion to a cerium source solution is 0.3);
7) 2g of copper sulfate pentahydrate was added thereto using a mixture of 50mL of 1, 2-butanediol, 2mL of deionized water and 50mL of isopropyl alcohol as a solvent to prepare a copper source solution (the volume ratio of the copper source solution to the cerium source solution is 0.9);
8) 50mL of the ceria dispersion (ceria solids content of 2 wt.%) was added dropwise to 102mL of the copper source solution using a advection pump (Cu: the atomic ratio of Ce is 0.36), the dropping speed is controlled to be 100mL/min (4.6L/min/mol Ce element), the stirring speed is 500r/min, the solvent thermal reaction is carried out after mixing, the solvent thermal temperature is 180 ℃, the solvent thermal time is 20h, after the solvent thermal reaction is finished, copper cerium oxide solid is separated through suction filtration, the liquid phase medium is used for suction filtration and washing for 4 times, the vacuum drying is carried out, the drying temperature is 80 ℃, and the drying time is 4h;
9) The n-heptane is used as a disperse phase, the copper cerium oxide solid prepared in the step 8) can be dispersed in the disperse phase in a transparent way to obtain brown copper cerium oxide transparent dispersoid, the physical diagram is shown in figure 2, the solid content is 2wt.%, no sediment is generated after standing for 24 months, and the dispersoid is kept transparent and stable.
The obtained copper cerium oxide was observed by a transmission electron microscope to obtain fig. 3, and it can be seen that the average particle diameter of the obtained copper cerium oxide particles was 2.3nm, and the particles were uniformly dispersed. The XRD patterns of the cerium oxide and the copper cerium oxide are shown in fig. 4, and the obtained cerium oxide and copper cerium oxide are fluorite type structures of cerium oxide, have good crystallinity, and the crystal form of the cerium oxide is not changed by adding copper elements. The EDX spectrum of the copper cerium oxide (fig. 5) shows that the copper elements are uniformly distributed in the cerium oxide nanoparticles.
0.25G of the prepared n-heptane phase transparent dispersion of copper cerium oxide (containing 5mg of copper cerium oxide catalyst) with a solid content of 2wt% was spin-coated on 2.5cm×3.5cm ITO glass, and the surface modifier was removed by irradiation with an ultraviolet ozone cleaner for 1 hour, and a photocatalytic carbon dioxide reduction experiment was performed in a gas-solid mode: the light source is a 300W xenon lamp, the irradiance is 100mW/cm 2, the device is vacuumized for three times, carbon dioxide is introduced to 0.26MPa, 200 mu L of deionized water is added, the temperature of circulating cooling water is 25 ℃, and the magnetic stirring rotating speed is 500r/min. Detecting the product hydrogen and oxygen content using a TCD detector (thermal conductivity detector); the FID detector (hydrogen flame ionization detector) detects the content of methane and carbon monoxide in the product. Fig. 6 is a diagram of an experimental apparatus. Fig. 7 shows experimental results of photocatalytic carbon dioxide reduction of the copper cerium oxide obtained in example 1 using a gas-solid method. The results show that the products are methane, hydrogen and carbon monoxide, and the yield of methane is 41 mu mol/g/h.
Example 2
The preparation process of oil soluble monodisperse nanometer cerium oxide catalyst includes the following steps:
1) 12g of cerium chloride heptahydrate was dissolved in a mixture of 40mL of chloroform, 40mL of methanol and 40mL of deionized water to prepare a cerium source solution;
2) 2mL of triethanolamine was dissolved in a mixture of 1mL of benzyl alcohol and 60mL of deionized water to prepare an alkali source solution (the volume ratio of alkali source solution to cerium source solution was 0.5);
3) 1.3g of cetyl ammonium bromide was dissolved in a mixture of 50mL of N, N-dimethylformamide and 50mL of deionized water to prepare a surface modifier solution (volume ratio of surface modifier solution to cerium source solution: 0.8);
4) Dropwise adding an alkali source solution into a cerium source solution, controlling the dropwise adding speed to be 100mL/min (3.1L/min/mol Ce element), reacting at 15 ℃, and stirring at 500r/min to obtain a reaction solution;
5) Dropwise adding a surfactant solution into the reaction solution obtained in the step 4) through a advection pump, controlling the dropwise adding speed to be 2mL/min (0.06L/min/mol Ce element), stirring the mixture at the speed of 500r/min, the modification reaction temperature to be 15 ℃, the modification reaction time to be 3h, centrifuging to separate cerium oxide solid after the modification reaction is finished, centrifuging and washing the cerium oxide solid for 5 times by taking cyclohexane as a liquid phase medium, and freeze-drying the cerium oxide solid at the drying temperature of-5 ℃ for 30h;
6) Taking 5mL of dichloromethane as a disperse phase, and transparently dispersing the cerium oxide solid prepared in the step 5) in the disperse phase to obtain a brown cerium oxide transparent dispersion, wherein a physical diagram is shown in FIG. 8, and the solid content is 20 wt% (the volume ratio of the cerium oxide dispersion to a cerium source solution is 0.04);
7) A copper source solution (the volume ratio of the copper source solution to the cerium source solution was 0.9) was prepared by adding 0.8g of copper stearate to a mixture of 10mL of n-hexane, 50mL of ethanol and 50mL of toluene as a solvent;
8) Dropwise adding 110mL of the copper source solution obtained in step 7) to 5mL of the cerium oxide dispersion (cerium oxide solid content 20 wt.%) obtained in step 6) by means of a peristaltic pump (Cu: the atomic ratio of Ce is 0.04), the dropping speed is 5mL/min (0.15L/min/mol Ce element), the solvothermal reaction is carried out after the mixture is completed, the solvothermal temperature is 130 ℃, the solvothermal time is 48 hours, after the solvothermal reaction is finished, copper cerium oxide solid is separated through centrifugation, the copper cerium oxide solid is centrifugally washed for 4 times by taking tetrahydrofuran as a liquid phase medium, and the drying temperature is 90 ℃ and the drying time is 10 hours; acetonitrile is used as a disperse phase, the prepared copper cerium oxide solid can be dispersed in the disperse phase in a transparent way to obtain brown copper cerium oxide transparent dispersion, the physical diagram is shown in figure 9, the solid content is 2wt.%, no sediment is generated after standing for 24 months, and the dispersion is kept transparent and stable.
0.25G of the n-heptane phase transparent dispersion of copper cerium oxide (containing 5mg of copper cerium oxide catalyst) prepared above and having a solid content of 2wt% was irradiated with an ultraviolet ozone cleaner for 1 hour to remove the surface modifier, and then mixed with 10mL of deionized water, and subjected to a photocatalytic carbon dioxide reduction experiment in a liquid-solid mode: the light source is a 300W xenon lamp, the irradiance is 100mW/cm 2, the device is vacuumized for three times, the carbon dioxide is aerated for 20min, the temperature of circulating cooling water is 25 ℃, and the magnetic stirring rotating speed is 500r/min. Detecting the product hydrogen and oxygen content using a TCD detector (thermal conductivity detector) of gas chromatography; the FID detector (hydrogen flame ionization detector) detects the content of methane and carbon monoxide in the product. The products formic acid, acetic acid, methanol and ethanol content were detected by liquid chromatography. Fig. 10 is an experimental result of photocatalytic carbon dioxide reduction using a liquid-solid method for the copper cerium oxide obtained in example 2. The results showed that the products were formic acid and carbon monoxide, formic acid being the main product with a yield of 8mmol/g/h.
Example 3
Example 1 was repeated except that in step 3), KH560 was changed to an equivalent amount of polyethylene glycol-4000; the cerium oxide produced in step 5) is well dispersible in step 6) with a mixture of 20mL of ethanol and 20mL of ethylene glycol as the dispersed phase, and the desired copper cerium oxide dispersion can be obtained in the subsequent step. The results show that the expected product can be obtained by changing the type of the surface modifier in the step 3) from the silane coupling agent to polyethylene glycol.
Example 4
Example 1 was repeated except that in step 3), KH560 was changed to an equivalent amount of trimethyloxonium tetrafluoroborate; the cerium oxide produced in step 5) is well dispersible in step 6) with a mixture of 20mL of ethanol and 20mL of ethylene glycol as the dispersed phase, and the desired copper cerium oxide dispersion can be obtained in the subsequent step. The result shows that the expected product can be obtained by changing the type of the surface modifier in the step 3) from the silane coupling agent to the fluoroborate.
Example 5
Example 2 was repeated except that in step 3), cetylammonium bromide was changed to an equal amount of lauric acid; the cerium oxide produced in step 5) is well dispersible in step 6) with 5mL of methylene chloride as the dispersed phase, and the desired copper cerium oxide dispersion can be obtained in the subsequent step. The results show that the expected product can be obtained by changing the type of the surface modifier in step 3) from a cationic surfactant to a long chain alkyl acid.
Comparative example 1
Example 1 was repeated except that in step 3) KH560 was changed to an equivalent amount of distearoyloxy isopropyl aluminate; the results show that changing the kind of the surface modifier in step 3), cerium oxide prepared in step 5) cannot obtain a well dispersed phase of 20mL of ethanol and 20mL of ethylene glycol mixture as a dispersed phase in step 6), and cerium oxide nanoparticles are precipitated in the dispersed phase, so that the intended copper cerium oxide dispersion cannot be obtained later.
Comparative example 2
Example 2 was repeated except that in step 8) the ceria dispersion was changed to an equivalent amount of a zirconia dispersion (5 mL in the same manner, methylene chloride was used as the dispersed phase, the solid content of zirconia was 20wt.%, and the particle diameter of zirconia was 3 nm), and a mixture of zirconia and cuprous oxide nanoparticles was obtained, the transmission electron micrograph and the corresponding physical photograph thereof were shown in fig. 11. This comparative experiment demonstrates that when other kinds of metal oxides are used instead of ceria, a separate copper oxide is easily formed when elemental copper is added.
It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. Not all embodiments are exhaustive. All obvious changes or modifications which come within the spirit of the invention are desired to be protected.

Claims (10)

1. A sub-nano-scale monodisperse copper-cerium oxide catalyst dispersion, characterized in that the sub-nano-scale monodisperse copper-cerium oxide particles and a liquid phase medium; the sub-nano-level copper cerium oxide is characterized in that copper elements are uniformly distributed and doped in cerium dioxide particles, the surface of the sub-nano-level monodisperse copper cerium oxide particles is coated with a surface modifier layer, and nano cerium dioxide particles coated with the surface modifier layer are uniformly dispersed in a liquid phase medium to form transparent dispersoids;
The solid content of the sub-nano-scale copper cerium oxide in the transparent dispersion is 0.005-60 wt%, and the one-dimensional size of the sub-nano-scale copper cerium oxide particles is 0.5-3 nm; cu: the molar ratio of Ce is 0.0001-3: 1.
2. A sub-nano-scale monodisperse copper cerium oxide catalyst dispersion according to claim 1, wherein said surface modifier layer comprises one or more of the following: n-butyric acid, n-caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, oleylamine, sodium oleate, sodium laurate, sodium stearate, [3- (methacryloyloxy) propyl ] trimethoxysilane (KH 570), gamma-glycidoxypropyl trimethoxysilane (KH 560), (3-aminopropyl) triethoxysilane (KH 550), (3-mercaptopropyl) trimethoxysilane, sodium dodecyl sulfate, cetyl ammonium bromide, tween-80, polyethylene glycol-200, polyethylene glycol-4000, polyethylene glycol-10000, trimethyloxonium tetrafluoroborate, triethyloxotetrafluoroborate, nitrotetrafluoroborate, tribenzyl carbonium tetrafluoroborate, ammonium fluoroborate.
The liquid phase medium comprises one or more of the following: formamide, N-dimethylformamide, methanol, ethanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, toluene, benzene, benzyl alcohol, cyclohexane, N-hexane, N-heptane, petroleum ether (30-60 ℃), petroleum ether (60-90 ℃), methylene chloride, chloroform, white oil, naphtha, castor oil, diesel oil, methyl isobutyl ketone, methyl methacrylate, 3-phenoxybenzyl acrylate.
3. A process for preparing a sub-nano-scale monodisperse copper cerium oxide catalyst dispersion according to claim 1 or 2, comprising the steps of:
1) Adding a cerium source into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a cerium source solution;
2) Taking water, an organic solvent or a mixture of water and the organic solvent as a solvent, and adding an alkali source into the solvent to prepare an alkali source solution;
3) Adding a surface modifier into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a surface modifier solution;
4) Mixing the cerium source solution in the step 1) and the alkali source solution in the step 2), and continuing to react after mixing;
5) Mixing the surface modifier solution with the mixture obtained in the step 4), continuing the modification reaction after mixing, carrying out solid-liquid separation after the reaction, and washing and drying the separated cerium dioxide solid;
6) Taking water, an organic solvent or a mixture of water and the organic solvent as a disperse phase, and washing and drying the cerium dioxide solid to be transparent dispersed in the disperse phase to obtain a cerium dioxide transparent dispersion;
7) Adding a copper source into water, an organic solvent or a mixture of water and the organic solvent serving as a solvent to prepare a copper source solution;
8) Mixing the cerium dioxide transparent dispersion in the step 6) with the copper source solution in the step 7), carrying out solvothermal reaction, carrying out solid-liquid separation after the reaction, washing and drying the separated copper cerium oxide solid, and dispersing the washed and dried copper cerium oxide solid in a liquid phase medium to obtain the product of the sub-nano monodisperse copper cerium oxide catalyst dispersion.
4. A method according to claim 3, wherein in step 1) the cerium source is selected from one or more of the following: the cerium source is selected from one or more of the following: cerium fluoride, cerium iodide, cerium bromide, anhydrous cerium sulfate, tetrahydrated cerium sulfate, anhydrous cerium chloride, heptahydrated cerium chloride, hexahydrated cerium nitrate, cerium oxalate hydrate, cerium (III) carbonate hydrate, cerium (III) acetate hydrate;
In step 1), the organic solvent is selected from one or more of the following substances: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, dichloromethane, chloroform, N-dimethylformamide, dimethyl sulfoxide; the ratio of water to the organic solvent in the solvent is any ratio;
In step 2), the alkali source is selected from one or more of the following substances: sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, triethylamine, and triethanolamine;
In step 2), the organic solvent is selected from one or more of the following substances: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, methylene chloride, chloroform, N-dimethylformamide, dimethyl sulfoxide, methyl isobutyl ketone; the ratio of water to the organic solvent in the solvent is any ratio; the ratio of water to the organic solvent in the solvent is any ratio;
In step 3), the surface modifier is selected from one or more of the following: n-butyric acid, n-caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, oleylamine, sodium oleate, sodium laurate, sodium stearate, [3- (methacryloyloxy) propyl ] trimethoxysilane (KH 570), gamma-glycidoxypropyl trimethoxysilane (KH 560), (3-aminopropyl) triethoxysilane (KH 550), (3-mercaptopropyl) trimethoxysilane, sodium dodecyl sulfate, cetyl ammonium bromide, tween-80, polyethylene glycol-200, polyethylene glycol-4000, polyethylene glycol-10000, trimethyloxonium tetrafluoroborate, triethyloxotetrafluoroborate, nitrotetrafluoroborate, tribenzyl carbonium tetrafluoroborate, ammonium fluoroborate;
In step 3), the organic solvent is selected from one or more of the following: methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, ethylene glycol, glycerol, benzyl alcohol, toluene, tetrahydrofuran, methylene chloride, chloroform, N-dimethylformamide, dimethyl sulfoxide, methyl isobutyl ketone; the ratio of water to the organic solvent in the solvent is any ratio;
In step 6), the organic solvent is selected from one or more of the following: formamide, N-dimethylformamide, methanol, ethanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, toluene, benzene, benzyl alcohol, cyclohexane, N-hexane, N-heptane, petroleum ether (30-60 ℃), petroleum ether (60-90 ℃), methylene chloride, chloroform, white oil, naphtha, castor oil, diesel oil, methyl isobutyl ketone, methyl methacrylate, 3-phenoxybenzyl acrylate;
In step 7), the copper source is selected from one or more of the following: copper gluconate, copper acetylacetonate, copper fluoroborate, copper citrate, copper acetate monohydrate, copper isooctanoate, anhydrous copper acetate, basic copper carbonate, copper (II) tartrate hydrate, copper oxalate, copper acetate monohydrate, copper butyrate, copper stearate, anhydrous copper sulfate, copper sulfate pentahydrate, basic copper sulfate, anhydrous copper chloride, copper chloride dihydrate, copper nitrate trihydrate; the organic solvent is selected from one or more of the following substances: oleic acid, linoleic acid, oleylamine, methanol, ethanol, isopropanol, toluene, benzyl alcohol, cyclohexane, n-hexane, 1, 2-butanediol; the ratio of water to organic solvent in the solvent is any ratio.
5. A method according to claim 3, wherein in step 1), the cerium source solution concentration is 0.01wt.% to 60 wt.%; in step 2), the alkali source solution concentration is 0.1wt.% to 50wt.%; in step 3), the surface modifier solution concentration is from 0.1wt.% to 80wt.%; the volume ratio of the alkali source solution to the cerium source solution is 0.01-6: 1, a step of; in the step 4), the cerium source solution and the alkali source solution are mixed in the following manner: adding a cerium source solution to an alkali source solution at a certain flow rate, or adding an alkali source solution to a cerium source solution at a certain flow rate; the flow rate is 0.01-100L/min/mol Ce element; the stirring speed is 200-800 r/min;
In step 5), the mixture of step 4) and the surfactant solution are mixed in the following manner: adding a surface modifier solution to the mixture of step 4) at a flow rate; the flow rate is 0.03-90L/min/mol Ce element; the stirring speed is 200-800 r/min; the volume ratio of the mixture to the surfactant solution is 0.1-50:1;
Step 5) the liquid medium used for the washing is selected from one or more of the following: methanol, ethanol, isopropanol, toluene, cyclohexane, n-hexane, acetone, benzyl alcohol, tetrahydrofuran, methylene chloride, chloroform; washing is one or more of washing, filtering (suction filtration or press filtration, ultrafiltration, nanofiltration), dialysis and centrifugation; the washing times are 2 to 5 times; the drying mode is one or more of freeze drying, vacuum drying, normal pressure evaporating, rotary decompression evaporating, air blast drying, infrared irradiation and spray drying;
in the step 8), the mixing mode of the cerium oxide transparent dispersion and the copper source solution is as follows: adding the cerium oxide transparent dispersion to the copper source solution at a flow rate; the flow rate is 0.01-100L/min/mol Ce element; stirring speed is 0-800 r/min; the separation and washing mode is one or more of washing, filtering (suction filtration or filter pressing, ultrafiltration and nanofiltration), dialysis and centrifugation; the liquid medium used for washing is selected from one or more of the following: methanol, ethanol, isopropanol, toluene, cyclohexane, n-hexane, acetone, benzyl alcohol, tetrahydrofuran, methylene chloride, chloroform; the washing times are 2 to 5 times; the drying mode is one or more of the steps 8) of freeze drying, vacuum drying, normal pressure evaporation, rotary decompression evaporation, air blast drying, infrared irradiation and spray drying, wherein the Cu in the cerium oxide and copper source is as follows: the molar ratio of Ce is 0.0001-3: 1.
6. A method according to claim 3, wherein in step 1), the concentration of the cerium source solution is 0.1wt.% to 50wt.%; in step 2), the concentration of the alkaline source solution is 0.5wt.% to 40wt.%; in step 3), the concentration of the surfactant solution is from 0.5wt.% to 40wt.%; in the step 4), the volume ratio of the alkali source solution to the cerium source solution is 0.02-5: 1, a step of; in step 8), the cerium oxide and Cu in the copper source: the molar ratio of Ce is 0.005-2.7: 1.
7. A process according to claim 3, wherein in step 4) the reaction temperature is 10 to 150 ℃ and the reaction time is 0 to 3 hours; preferably, the reaction temperature is 15-95 ℃; the reaction time is 0 to 2.5 hours; in the step 8), the solvothermal reaction temperature is 80-260 ℃ and the solvothermal time is 2-96 h; the preferable solvothermal reaction temperature is 120-250 ℃; the solvothermal time is 2-72 h.
8. Use of a sub-nano-scale monodisperse copper cerium oxide catalyst according to claim 1 or 2 as a photocatalytic carbon dioxide reduction catalyst.
9. The use according to claim 8, wherein the photocatalytic carbon dioxide reduction system uses a gas-solid mode or a liquid-solid mode; the gas-solid mode is to load the prepared nano dispersion of the sub-nano monodisperse copper-cerium oxide catalyst on a carrier, remove a surfactant layer coated by the nano copper-cerium oxide catalyst by irradiation of an ultraviolet ozone light cleaner, take deionized water as a sacrificial agent, take carbon dioxide as a reactant, and carry out visible light irradiation reaction; the liquid-solid mode is that the nano dispersion of the sub-nano level monodisperse copper cerium oxide catalyst is directly added into a reaction system, a sacrificial agent is added, and carbon dioxide is taken as a reactant to carry out visible light irradiation reaction.
10. The use according to claim 9, wherein the carrier in the gas-solid mode is one or more of ITO glass, FTO glass, plain glass, hydrophilic carbon cloth, hydrophobic carbon cloth;
The loading mode in the gas-solid mode is one or more of infiltration, spin coating, knife coating and spray coating;
The photocatalytic carbon dioxide reduction product in the gas-solid mode is one or more of carbon monoxide, hydrogen, methane, ethylene and ethane;
the sacrificial agent in the liquid-solid mode is one or more of triethanolamine, triethylamine, N-dimethylformamide sodium sulfide, sodium sulfite and lactic acid;
The photocatalytic carbon dioxide reduction product in the liquid-solid mode is one or more of carbon monoxide, hydrogen, methane, ethylene, ethane, formic acid, acetic acid, methanol and ethanol.
CN202311801570.6A 2023-12-25 2023-12-25 Preparation method and application of sub-nano level monodisperse copper cerium oxide catalyst Pending CN118022752A (en)

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