CN116393135A - Preparation method of copper-based catalyst loaded with Cu atom clusters or Cu single atoms by mixed carrier - Google Patents

Preparation method of copper-based catalyst loaded with Cu atom clusters or Cu single atoms by mixed carrier Download PDF

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CN116393135A
CN116393135A CN202310082707.0A CN202310082707A CN116393135A CN 116393135 A CN116393135 A CN 116393135A CN 202310082707 A CN202310082707 A CN 202310082707A CN 116393135 A CN116393135 A CN 116393135A
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copper
raw material
based catalyst
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oxide
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王悦
马新宾
吕静
药大卫
王美岩
黄守莹
王胜平
赵玉军
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Zhejiang Research Institute Of Tianjin University
Tianjin University
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Zhejiang Research Institute Of Tianjin University
Tianjin University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • 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
    • 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
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/30—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group
    • C07C67/31—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by introduction of functional groups containing oxygen only in singly bound form
    • 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
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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Abstract

The invention discloses a preparation method of a copper-based catalyst with a mixed carrier loaded with Cu atom clusters or Cu single atoms, which comprises the following steps of (1) providing a substance of silicon dioxide loaded with copper oxide nano particles as a first raw material, wherein the particle size of the copper oxide nano particles is smaller than 4nm; (2) providing a substance with surface oxygen-containing defects as a second raw material; (3) Mixing the second raw material with the first raw material, and performing first-stage and second-stage treatment after mixing; or the first raw material is subjected to the first-stage reduction treatment, then is mixed with the second raw material, and is subjected to the second-stage treatment after being mixed; the copper-based catalyst is obtained after the treatment of the first stage and the second stage. The copper-based catalyst prepared by the invention has good effect on the selective hydrogenation production of intermediate methyl glycolate in the hydrogenation reaction of dimethyl oxalateCu composed of three copper atoms 3 The cluster is a catalyst, the reaction temperature is 200 ℃, the reaction pressure is 2.5MPa, and when the molar ratio of the fed hydrogen to the methyl glycolate reaches 80 percent, the yield of the methyl glycolate reaches 95 percent.

Description

Preparation method of copper-based catalyst loaded with Cu atom clusters or Cu single atoms by mixed carrier
Technical Field
The invention belongs to the technical field of copper-based catalysts, and particularly relates to a preparation method of a copper-based catalyst with a mixed carrier loaded with Cu atom clusters or Cu single atoms.
Background
Methyl glycolate is widely applied to the production of chemicals, medicines, pesticides, spices, dyes and the like as an important chemical raw material or solvent, and has a broad market prospect. At present, the main technological method for producing methyl glycolate is to produce methyl glycolate through catalytic coupling reaction of methyl formate and formaldehyde or polyoxymethylene. However, because the catalytic reaction needs to use a liquid strong acid catalyst, the process has the problems of serious equipment corrosion, large pollution and limited raw material sources. The process for preparing dimethyl oxalate by coupling synthesis gas with carbon monoxide and further hydrogenating to prepare methyl glycolate has the characteristics of high atom economy, mild reaction condition, high product selectivity, green environmental protection and the like, and is one of important paths for synthesizing methyl glycolate by a non-petroleum route. Wherein, the hydrogenation of dimethyl oxalate is the key link of the process.
The silver-based catalyst has better activity and selectivity in a methyl glycolate preparation process system by oxalate hydrogenation, and the yield of the silver-based catalyst can reach more than 90%. However, in silver-based catalysts, the mass fraction of metallic silver is often greater than 10%, so that the preparation cost of the catalyst is greatly increased, and the metallic silver is easily agglomerated and deactivated under the high-temperature hydrogen-rich condition of the reaction. When the copper-based catalyst is used for hydrogenating the oxalate, methyl glycolate generated in the reaction is easy to be excessively hydrogenated to generate ethylene glycol, so that the yield of the methyl glycolate is often lower than 84%. Therefore, in order to reduce the production cost of the catalyst and obtain methyl glycolate with higher yield, the design of a novel high-activity copper-based catalyst, so that the methyl glycolate produced by the hydrogenation of oxalate has high selectivity and yield, is the key for optimizing the technology of the process for preparing methyl glycolate from synthesis gas.
The present invention aims to solve the above-mentioned problems.
Disclosure of Invention
The first aspect of the invention provides a method for preparing a copper-based catalyst loaded with Cu atom clusters or Cu single atoms by a mixed carrier, wherein the copper-based catalyst comprises a carrier and an active component, the carrier is silicon dioxide and substances with surface oxygen defects, and the mass ratio of the silicon oxide to the substances with surface oxygen defects is 1 (3.6-7.2); the active component is a copper species, the copper species is Cu atom clusters composed of Cu monoatoms and/or Cu atoms, the Cu atom clusters are smaller than 0.8nm in size, and the loading amount of the copper species is 5% -7% based on the total mass of the copper-based catalyst;
the preparation method of the copper-based catalyst loaded with Cu atom clusters or Cu single atoms by the mixed carrier comprises the following steps:
(1) Providing a substance of a silicon dioxide loaded copper oxide nano particle as a first raw material, wherein the particle size of the copper oxide nano particle is smaller than 4nm;
(2) Providing a substance with surface oxygen-containing defects as a second raw material;
(3) Mixing the second raw material with the first raw material, and performing first-stage and second-stage treatment after mixing; or alternatively, the process may be performed,
the first raw material is subjected to first-stage reduction treatment, then is mixed with the second raw material, and is subjected to second-stage treatment after being mixed;
the copper-based catalyst is obtained after the treatment of the first stage and the second stage. The first stage of reduction treatment reduces copper oxide nano particles loaded on silicon dioxide into copper nano particles, and the second stage of treatment enables the copper nano particles to migrate to substances with oxygen defects on the surface to form Cu monoatoms or Cu atom clusters, so that the copper-based catalyst is obtained.
Preferably, the surface oxygen-containing defect substance is a surface oxygen-containing defect metal oxide selected from cerium oxide, zinc oxide, zirconium oxide, titanium oxide or manganese oxide.
Preferably, the silicon dioxide is of a layered structure, and the particle size of the substance with oxygen defects on the surface is 4.0 nm-20.0 nm.
Preferably, the average valence state of copper in the copper species is 0 to 1.
Preferably, the number of Cu atoms in the Cu atom cluster is less than 100, preferably less than 60, more preferably less than 30, still more preferably less than 15, still more preferably less than 6, most preferably less than 3.
Preferably, in the step (1), the mass percentage of copper in the substance of the silicon dioxide loaded copper oxide nano particles is 5% -50%.
Preferably, the preparation method of the silica-supported copper oxide nanoparticle substance in the step (1) comprises the following steps:
(11) Dissolving copper nitrate trihydrate in water, adding ammonia water, and stirring and mixing to obtain a first mixed solution;
(12) Dropwise adding silica sol into the first mixed solution, stirring, and then distilling to remove ammonia components in the first mixed solution to obtain a second mixed solution;
(13) And (3) filtering the second mixed solution obtained in the step (12), collecting a filter cake, washing, and roasting in an air atmosphere to obtain the substance of the silica-supported copper oxide nano particles.
Preferably, the concentration of the ammonia water in the step (11) is 20% -28%; the volume ratio of the ammonia water to the water is 1:1.12-1:2.31; the temperature of distillation in the step (12) is 60-90 ℃, and the pH value of the solution after distilling and removing the ammonia component in the first mixed solution is 6.5-8.5.
The addition amount of the copper nitrate trihydrate and the silica sol in the step (11) is designed according to the mass fraction of copper in the finally obtained silicon dioxide loaded copper oxide nano-particle substance, wherein the mass fraction of copper in the silicon dioxide loaded copper oxide nano-particle substance is 5% -50%.
The specific surface area of the first raw material prepared by the method is 400-600 m 2 Per gram, the average pore volume is 0.3-1.1 cm 3 And/g, wherein the average pore diameter is 3.0-10.0 nm, and the particle size of the copper oxide nano particles is smaller than 4nm.
Preferably, in the step (3), the mass ratio of the first raw material to the second raw material is 1:3.6-1:7.2;
the reduction treatment conditions of the first stage are as follows: treating for 4-6 hours in a first gas atmosphere at 180-400 ℃ to reduce copper oxide nano particles loaded on silicon dioxide into copper nano particles;
the second stage treatment conditions are as follows: and (3) in the second gas atmosphere at 180-300 ℃, treating for 20-150 h, and transferring the copper nano particles to substances with oxygen defects on the surface to form Cu atom clusters, thereby obtaining the copper-based catalyst.
Preferably, the first gas is a reducing gas, such as hydrogen; the second gas is a non-oxidizing gas, for example selected from nitrogen, hydrogen or argon; the flow rate of the first gas flow is 20-150 mL/g of material, and the flow rate of the second gas flow is 10-200 mL/g of material.
Among them, the migration includes migration by various mechanisms such as a copper atom volatilization-deposition mechanism, or a contact-transfer mechanism, etc., which are trapped at oxygen defects on the surface of a substance having oxygen defects on the surface and gradually grow from single atoms into copper nanoclusters. With the continuous migration of copper atoms on the copper nanoparticles, the size of the copper nanoparticles originally loaded on the surface of the silicon dioxide is gradually reduced to copper nanoclusters or even copper monoatomic forms, and the copper nanoclusters and/or copper monoatomic clusters are loaded on the upper surfaces of both the silicon dioxide carrier and the substances with surface oxygen defects in the obtained copper-based catalyst.
In the prior art prior to the present invention, mixing a metal precursor and a reducible metal oxide support at high temperature, performing a high temperature treatment, and migrating metal species to the surface of cerium oxide via an ostwald ripening mechanism to form monoatomic species is a common method for preparing monoatomic catalysts. However, problems in the process of preparing copper-based catalysts using the prior art are: copper oxide particles are larger than 4nm before migration, copper atom migration cannot be performed at a low temperature, so in order to promote migration of copper species on silicon dioxide, the treatment temperature is 600-1000 ℃ in the conventional migration process, and the high-temperature treatment environment can cause copper atoms on substances with surface oxygen-containing defects to be quickly agglomerated from Cu single atoms into copper nano particles with the size of less than 0.8nm, which is composed of several Cu atoms, if the number of copper atoms exceeds a certain number.
Here, neglected by all the prior art before and noticed by the inventors that the distinction between "copper nanoparticles" and "copper clusters" is not strictly accepted by the academia, but in the present invention, copper atom aggregates with a size of more than 2nm are referred to as "copper nanoparticles", copper atom aggregates with a size of less than 0.8nm are referred to as "copper clusters", and copper atom aggregates with a size of between 0.8 and 2nm are referred to as "copper sub-nanoparticles". Copper-based catalysts, in which the active component copper exists in the form of "copper nanoparticles" or "copper sub-nanoparticles" without exception, have not been reported in the form of "copper clusters", and more recently, have been reported for the catalytic performance of the latter.
According to the invention, firstly, a substance of the silicon dioxide loaded copper oxide nano particles is prepared by an ammonia distillation method to serve as a first raw material, wherein the particle size of the copper oxide nano particles in the first raw material is smaller than 4nm, and the copper oxide nano particles on the first raw material can be reduced into copper nano particles at the temperature of 200-400 ℃ and further migrate to the second raw material to form Cu atom clusters composed of Cu single atoms and/or Cu atoms, and the Cu single atoms or Cu atom clusters are prevented from further agglomerating into copper nano particles due to the low migration temperature, so that the Cu-based catalyst loaded with Cu atom clusters or Cu single atoms by the mixed carrier is obtained.
Preferably, the dimethyl oxalate is gasified and mixed with hydrogen and then enters the reactor, and the mass airspeed of the dimethyl oxalate is 0.5 to 5 hours -1 The molar ratio of the hydrogen and the ester (hydrogen and ester ratio for short) is 20-150, the reaction temperature in the reactor is 160-240 ℃, and the reaction pressure is 1.5-3.5 MPa.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention realizes the large-scale preparation of a copper-based catalyst with an active component of Cu single atoms and/or Cu atom clusters composed of a plurality of atoms for the first time, wherein the carrier of the copper-based catalyst is silicon dioxide and substances with surface oxygen defects, and the mass ratio of the silicon oxide to the substances with surface oxygen defects is 1 (3.6-7.2); the active component of the copper-based catalyst is a copper species, the copper species is Cu atom clusters composed of Cu monoatoms and/or Cu atoms, the Cu atom clusters are smaller than 0.8nm in size, and the loading amount of the copper species is 5% -7% based on the total mass of the copper-based catalyst.
2. According to the invention, firstly, a substance of the silicon dioxide loaded copper oxide nano particles is prepared by an ammonia distillation method to serve as a first raw material, wherein the particle size of the copper oxide nano particles in the first raw material is smaller than 4nm, and the copper oxide nano particles on the first raw material can be reduced into copper nano particles at the temperature of 200-400 ℃ and further migrate to the second raw material to form Cu atom clusters composed of Cu single atoms and/or Cu atoms, and the Cu single atoms or Cu atom clusters are prevented from further agglomerating into copper nano particles due to the low migration temperature, so that the Cu-based catalyst loaded with Cu atom clusters or Cu single atoms by the mixed carrier is obtained.
3. The copper-based catalyst of the invention is used for the hydrogenation reaction of dimethyl oxalateThe method has good effect in producing the intermediate product methyl glycolate through selective hydrogenation. Wherein Cu consisting of three copper atoms 3 The cluster is a catalyst, the reaction temperature is 200 ℃, the reaction pressure is 2.5MPa, the yield of the intermediate product methyl glycolate reaches 95% when the ratio of the fed hydrogen to the ester is 80, but when the oxide-supported copper-based catalyst is used for the reaction, the yield of the intermediate product methyl glycolate is only 84%, and the yield of the intermediate product methyl glycolate corresponding to the noble metal silver-based catalyst can usually reach about 93%, so the Cu of the invention 3 The cluster catalyst is used for the reaction, and the yield of the intermediate methyl glycolate is far higher than that of the copper-based catalyst reported in the prior art and is equivalent to that of the noble metal silver-based catalyst. The copper-based catalyst can replace silver-based catalyst to be developed as an industrial catalyst. Greatly saves the production cost of the catalyst and reduces the energy consumption required by product separation.
4. The copper-based catalyst provided by the invention has excellent stability in the hydrogenation process of dimethyl oxalate, so that the production process for preparing methyl glycolate through hydrogenation of dimethyl oxalate adopted by the invention has stability.
Drawings
FIG. 1 is a spherical aberration-correcting transmission electron microscope image of a copper-based catalyst sample 1 prepared in example 1 and a DFT simulation image of the structure, wherein the a-image is a spherical aberration-correcting transmission electron microscope image and S1 and S2 directional contrast signal intensity images, the b-image is a partial enlarged image of the a-image box, the c-image is a DFT simulation image of the corresponding structure, the copper species of the copper-based catalyst sample 1 is a Cu cluster (Cu 3 )；
Fig. 2 is a transmission electron micrograph of a first raw material and a second raw material in the preparation process of example 1 and example 6, wherein a and b are transmission electron micrograph of the first raw material (a material of silica-supported copper oxide nanoparticles) after reduction in a hydrogen atmosphere at 300 ℃ for 4 hours, and c and d are transmission electron micrograph of the second raw material (ceria precursor);
FIG. 3 is a spherical aberration correcting transmission electron microscope image of copper-based catalyst sample 2 prepared in example 3, in which the copper species of copper-based catalyst sample 1 is Cu atom cluster (Cu 30 )；
FIG. 4 is a graph of the X-ray absorption fine structure of the copper-based catalyst samples 1-3 prepared in examples 1-3 and the standard of metallic copper, cuprous oxide and cupric oxide, wherein A is a graph of the X-ray absorption near-edge structure, B is a graph of the guide function of the graph of the X-ray absorption near-edge structure, and C is a graph of the extended X-ray absorption fine structure;
FIG. 5 shows the results of the conversion of dimethyl oxalate and the selectivity of Ethylene Glycol (EG) to Methyl Glycolate (MG) in the hydrogenation of dimethyl oxalate using copper-based catalyst samples 1-3 prepared in examples 1-3, wherein the reaction conditions were: the reaction temperature is 200 ℃, the reaction pressure is 2.5MPa, the hydrogen-ester ratio is 80, and the mass airspeed of the dimethyl oxalate is 3h -1 ；
FIG. 6 shows the evaluation results of methyl oxalate hydrogenation to methyl glycolate in example 5;
FIG. 7 is a spherical aberration correcting transmission electron microscope image and S2 directional contrast signal intensity image of copper-based catalyst sample 6 prepared in example 6.
Detailed Description
The invention is described in further detail below with reference to the drawings and the detailed description. It should be noted that: the following examples are illustrative, not limiting, and are not intended to limit the scope of the invention. The raw materials required in the following examples and comparative examples are all commercially available.
Example 1
Preparation of a first feedstock (silica-supported copper oxide nanoparticle material):
18g of copper nitrate trihydrate is weighed, added with 100mL of deionized water, stirred and dissolved, and 70mL of 28% ammonia water is slowly added to prepare copper ammonia solution, and stirred uniformly at 30 ℃. Then, 30% by mass of silica sol was added dropwise to the solution, and aging was continued with stirring for 4 hours. The ammonia in the solution was distilled off by heating to 80℃and the pH of the solution was monitored at any time. When ph=7, the temperature is reduced and the ammonia distillation process is stopped. Filtering and washing the obtained mixed solution, drying at 80 ℃, and roasting for 4 hours at 400 ℃ in an air atmosphere to obtain the substance of the silicon dioxide loaded copper oxide nano particles.
Preparation of a second raw material (ceria precursor):
25g of cerium oxide hexahydrate was weighed, ground uniformly in a mortar, and calcined at 250℃for 2 hours in an air atmosphere to obtain a cerium oxide precursor.
Fig. 2 is a transmission electron micrograph of a first raw material and a second raw material in the preparation process of example 1, wherein a and b are transmission electron micrographs of the first raw material (a material of silica-supported copper oxide nanoparticles) after reduction in a hydrogen atmosphere at 300 ℃ for 4 hours, and c and d are transmission electron micrograph of the second raw material (ceria precursor).
Copper-based catalyst sample 1 preparation:
the material of the silicon dioxide loaded copper oxide nano particles and cerium oxide are mixed according to the mass ratio of 1:3.6 mechanical mixing to obtain a raw material mixture, and then carrying out on-line reduction treatment and heat treatment on the raw material mixture to obtain a copper-based catalyst sample 1.
Copper-based catalyst sample 1 on-line treatment:
the in-line treatment of the copper-based catalyst sample 1 in this example was performed in a fixed bed reactor. Tabletting the raw material mixture which is not subjected to heat treatment, sieving the raw material mixture into particles with the size of 40-60 meshes, weighing 0.58g, placing the particles in an isothermal reactor, introducing hydrogen atmosphere, reducing the particles at 300 ℃ for 4 hours (first-stage reduction treatment), cooling the particles to 200 ℃ and keeping the temperature for 100 hours (second-stage reduction treatment), wherein the flow rate of the hydrogen gas is 20-150 mL/g, and obtaining the copper-based catalyst sample 1 used in the invention.
The characterization of the copper-based catalyst sample 1 is shown in fig. 1, wherein a graph a is a spherical aberration transmission electron microscope graph and S1 and S2 directional contrast signal intensity graphs, b is a partial enlarged graph of a graph box, and c is a DFT simulation graph of a corresponding structure. It can be seen that the atomic spacing of Cu-Cu is 0.20nm and the spacing of Ce-Ce is 0.31nm at this angle, which is hardly shown in the spherical aberration transmission electron microscope image due to the low O atomic number. And since Ce has an atomic number greater than that of Cu, it is also apparent from the signal intensities in the S1 and S2 directions that the presence of Cu clusters having a form of about 3 copper species on the surface of cerium oxide is observed, so that the copper-based catalyst sample 1 obtained in this example is abbreviated as Cu 3 。
Examples 2 to 3
Examples 2-3 copper-based catalyst samples 2-3 were prepared by controlling the mass percent of copper in the mass of the silica-supported copper oxide nanoparticles, respectively, to control the size of the copper species in the copper-based catalyst. Specific preparation conditions are shown in Table 1, and experimental conditions not shown in Table 1 represent the same as in example 1.
TABLE 1 influence of different copper nitrate additions on copper species in copper-based catalysts
Figure BDA0004067932990000071
The spherical aberration correcting transmission electron microscope of the copper-based catalyst sample 3 is shown in FIG. 3.
As can be seen from fig. 3, the copper oxide nanoparticles supported on the silica were reduced to copper nanoparticles, and the copper nanoparticles successfully migrated to the cerium oxide to form a Cu atom cluster consisting of thirty copper atoms, so that the copper-based catalyst sample 3 was abbreviated as Cu 30 。
Meanwhile, fig. 4 is an X-ray absorption fine structure spectrum of copper-based catalyst samples 1 to 3, wherein a is an X-ray absorption near-edge structure spectrum (XANES diagram), B is a guide function diagram of the X-ray absorption near-edge structure spectrum, C is an extended X-ray absorption fine structure spectrum (EXASF diagram), in which an atomic distance is 1.85 angstroms as a peak of cu—o bond and an atomic distance is 2.53 angstroms as a peak of cu—cu bond. The average valence state of this Cu cluster can be demonstrated between 0 and +1 from the XANES plot of copper in fig. 4; since the Cu element EXAFS plot only has peaks of Cu-O bonds, no peaks of Cu-Cu bonds appear, it can be demonstrated that the Cu species in the catalyst of example 2 exist in the form of a single atom; since the peak of the Cu-Cu bond in the Cu element EXAFS pattern in the sample of example 1 is very weak, the Cu cluster consisting of 2 to 3 Cu atoms of the Cu species of example 1 can be illustrated by fitting the coordination number of the peak to be 2.6; since the peak of the Cu-Cu bond in the Cu element EXAFS pattern in the sample of example 3 is weak, by fitting the coordination number thereof to 4.8, the Cu cluster having the existence form of 0.8nm of the Cu species in example 3 can be obtained by calculation.
Example 4
In this example, the gas phase dimethyl oxalate hydrogenation reaction was carried out in a fixed bed reactor. Tabletting 1-3 of copper-based catalyst sample, sieving to obtain particles with the size of 40-60 meshes, weighing 0.58g, placing into an isothermal reactor, controlling the reaction temperature in the reactor to 200 ℃, gasifying dimethyl oxalate and mixing with hydrogen into a reaction tube, wherein the hydrogen-ester ratio is 80, and the mass airspeed of the dimethyl oxalate is 3h -1 The reaction was carried out at 2.5 MPa. The product was analyzed by gas chromatography to obtain components of dimethyl oxalate (DMO), ethylene Glycol (EG), methyl Glycolate (MG) and ethanol (EtOH), and other by-product components were extremely small, and analysis was performed to obtain the conversion of dimethyl oxalate and the selectivity of Ethylene Glycol (EG) and Methyl Glycolate (MG). The conversion of dimethyl oxalate and the selectivity results for Ethylene Glycol (EG) and Methyl Glycolate (MG) are shown in FIG. 4.
As can be seen from FIG. 5, as the Cu cluster size in the copper-based catalyst increases, the selectivity of the intermediate Methyl Glycolate (MG) decreases, while the selectivity of Ethylene Glycol (EG) increases, when Cu consisting of three Cu atoms is used 3 The cluster catalyst (copper-based catalyst sample 1) is used in dimethyl oxalate hydrogenation reaction, the reaction temperature is 200 ℃, the reaction pressure is 2.5MPa, and when the feeding hydrogen-ester ratio is 80, the yield of the intermediate product methyl glycolate reaches 95%, which is far higher than that of the copper-based catalyst reported in the prior art, and the catalytic activity of the catalyst is equivalent to that of the noble metal silver-based catalyst.
Example 5
The catalyst precursor and the mixing means in this example were the same as those in example 1, but in the on-line treatment, the catalyst was reduced only at 300℃for 4 hours, and the catalyst was not heat-treated at 200℃for 100 hours, but evaluated by directly carrying out the oxalate hydrogenation reaction at 200 ℃. The evaluation conditions were the same as in example 1. By the embodiment, the influence of the atomic migration phenomenon of the copper nano particles on the hydrogenation reaction performance of the oxalate can be observed in the evaluation process, and the stability of the oxalate can be tested. The specific results are shown in FIG. 6.
As a result of the reduction at 300 ℃ for 4 hours before the reaction, the copper oxide nanoparticles supported on the silica were reduced to copper nanoparticles, and as can be seen from fig. 6, the copper species were present in the form of copper nanoparticles in the catalyst at the initial stage of the reaction, the selectivity of the product catalyzing the hydrogenation of oxalate was mainly ethylene glycol, and the yield of methyl glycolate was extremely low; with the extension of the reaction time, as the reaction is carried out in a non-oxidizing atmosphere at 200 ℃, copper nano particles loaded on silicon dioxide in the catalyst gradually migrate to cerium oxide to form Cu atom clusters consisting of 2-3 copper atoms, the product of catalyzing the hydrogenation of oxalate gradually changes from ethylene glycol to methyl glycolate, and finally, the yield of methyl glycolate is up to 95%, and the structure of the Cu atom clusters can be kept stable all the time, so that the stable yield of methyl glycolate is obtained.
Example 6
This example is the preparation of copper-based catalyst sample 4:
the preparation method of the first raw material and the second raw material is the same as in example 1, and then the first raw material is subjected to the first-stage reduction treatment, then mixed with the second raw material, and then subjected to the second-stage reduction treatment to obtain a copper-based catalyst sample 4, specifically: firstly, placing a first raw material into an isothermal reactor, introducing hydrogen atmosphere, reducing at 300 ℃ for 4 hours, then mixing with a second raw material, and keeping at 200 ℃ for 100 hours in nitrogen atmosphere after mixing; the flow rate of the first stage hydrogen gas flow is 20-150 mL/g, and the flow rate of the second stage nitrogen gas flow is 10-200 mL/g.
As can be seen from fig. 7 for the spherical aberration correcting transmission electron microscope of the copper-based catalyst sample 4, similarly to fig. 1 for the copper-based catalyst sample 4, the copper oxide nanoparticles supported on the silica were reduced to copper nanoparticles, and the copper nanoparticles successfully migrated to the cerium oxide to form Cu atom clusters composed of three copper atoms, so that the preparation method can also obtain the copper-based catalyst of the Cu atom clusters composed of several Cu atoms of the copper species according to the present invention.
The foregoing has described exemplary embodiments of the invention, it being understood that any simple variations, modifications, or other equivalent arrangements which would not unduly obscure the invention may be made by those skilled in the art without departing from the spirit of the invention.

Claims (10)

1. The preparation method of the copper-based catalyst loaded with Cu atom clusters or Cu monoatoms by using the mixed carrier is characterized in that the copper-based catalyst comprises a carrier and an active component, wherein the carrier is silicon dioxide and substances with surface oxygen defects, and the mass ratio of the silicon oxide to the substances with surface oxygen defects is 1 (3.6-7.2); the active component is a copper species, the copper species is Cu atom clusters composed of Cu monoatoms and/or Cu atoms, the Cu atom clusters are smaller than 0.8nm in size, and the loading amount of the copper species is 5% -7% based on the total mass of the copper-based catalyst;
the preparation method of the copper-based catalyst comprises the following steps:
(1) Providing a substance of a silicon dioxide loaded copper oxide nano particle as a first raw material, wherein the particle size of the copper oxide nano particle is smaller than 4nm;
(2) Providing a substance with surface oxygen-containing defects as a second raw material;
(3) Mixing the second raw material with the first raw material, and performing first-stage and second-stage treatment after mixing; or alternatively, the process may be performed,
the first raw material is subjected to first-stage reduction treatment, then is mixed with the second raw material, and is subjected to second-stage treatment after being mixed;
the copper-based catalyst is obtained after the treatment of the first stage and the second stage.
2. The method according to claim 1, wherein the substance having surface oxygen-containing defects is a metal oxide having surface oxygen-containing defects, and the metal oxide having surface oxygen-containing defects is selected from cerium oxide, zinc oxide, zirconium oxide, titanium oxide and manganese oxide.
3. The method according to claim 1, wherein the silica has a layered structure, and the surface oxygen-containing defect substance has a particle diameter of 4.0nm to 20.0nm; the average valence of copper in the copper species is 0 to 1.
4. The method of claim 1, wherein the number of Cu atoms in the Cu atom cluster is less than 100, preferably less than 60, more preferably less than 30, still more preferably less than 15, still more preferably less than 6, most preferably less than 3.
5. The preparation method according to claim 1, wherein the mass percentage of copper in the substance of the silica-supported copper oxide nanoparticle in the step (1) is 5% to 50%.
6. The process according to claim 1, wherein the specific surface area of the first raw material in step (1) is 400 to 600m 2 Per gram, the average pore volume is 0.3-1.1 cm 3 And/g, wherein the average pore diameter is 3.0-10.0 nm, and the particle size of the copper oxide nano particles is smaller than 4nm.
7. The method according to claim 1, wherein the method for producing the silica-supported copper oxide nanoparticle substance in step (1) comprises the steps of:
(11) Dissolving copper nitrate trihydrate in water, adding ammonia water, and stirring and mixing to obtain a first mixed solution;
(12) Dropwise adding silica sol into the first mixed solution, stirring, and then distilling to remove ammonia components in the first mixed solution to obtain a second mixed solution;
(13) And (3) filtering the second mixed solution obtained in the step (12), collecting a filter cake, washing, and roasting in an air atmosphere to obtain the substance of the silica-supported copper oxide nano particles.
8. The method according to claim 7, wherein the concentration of ammonia water in the step (11) is 20% to 28%; the volume ratio of the ammonia water to the water is 1:1.12-1:2.31; the temperature of distillation in the step (12) is 60-90 ℃, and the pH value of the solution after distilling and removing the ammonia component in the first mixed solution is 6.5-8.5.
9. The method according to claim 1, wherein the mass ratio of the first raw material to the second raw material in the step (3) is 1:3.6 to 1:7.2;
the reduction treatment conditions of the first stage are as follows: treating for 4-6 h in a first gas atmosphere at 180-400 ℃;
the second stage treatment conditions are as follows: and treating for 20-150 h in a second gas atmosphere at 180-300 ℃.
10. The method of claim 9, wherein the first gas is a reducing gas selected from hydrogen; the second gas is a non-oxidizing gas selected from nitrogen, hydrogen or argon; the flow rate of the first gas flow is 20-150 mL/g of material, and the flow rate of the second gas flow is 10-200 mL/g of material.
CN202310082707.0A 2023-02-08 2023-02-08 Preparation method of copper-based catalyst loaded with Cu atom clusters or Cu single atoms by mixed carrier Pending CN116393135A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5455372A (en) * 1993-03-12 1995-10-03 Ube Industries, Ltd. Method of producing a glycolic acid ester
CN110420669A (en) * 2019-06-18 2019-11-08 南京大学 Cu cluster preparation method and catalysis CO2React purposes
CN111774050A (en) * 2020-07-17 2020-10-16 兰州理工大学 Preparation method and application of supported catalyst for catalyzing dimethyl oxalate hydrogenation
CN113797931A (en) * 2021-09-29 2021-12-17 中触媒新材料股份有限公司 Dimethyl oxalate hydrogenation catalyst, preparation method and application thereof
CN115382541A (en) * 2022-08-19 2022-11-25 天津大学 Method for regulating existence form of Rh species in rhodium-based catalyst

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5455372A (en) * 1993-03-12 1995-10-03 Ube Industries, Ltd. Method of producing a glycolic acid ester
CN110420669A (en) * 2019-06-18 2019-11-08 南京大学 Cu cluster preparation method and catalysis CO2React purposes
CN111774050A (en) * 2020-07-17 2020-10-16 兰州理工大学 Preparation method and application of supported catalyst for catalyzing dimethyl oxalate hydrogenation
CN113797931A (en) * 2021-09-29 2021-12-17 中触媒新材料股份有限公司 Dimethyl oxalate hydrogenation catalyst, preparation method and application thereof
CN115382541A (en) * 2022-08-19 2022-11-25 天津大学 Method for regulating existence form of Rh species in rhodium-based catalyst

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JINLONG GONG ET AL.: ""Synthesis of Ethanol via Syngas on Cu/SiO2 Catalysts with Balanced Cu0−Cu+ Sites"", 《J. AM. CHEM. SOC.》, vol. 134, 31 December 2012 (2012-12-31), pages 13922 *
刘小刚等: "氧化物负载的单原子催化剂研究进展", 《信阳师范学院学报(自然科学版)》, vol. 35, no. 3, 31 December 2022 (2022-12-31), pages 504 - 509 *

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