CN118477660B - Preparation method and application of carbon nano tube packaged CuAg bimetallic catalyst - Google Patents

Preparation method and application of carbon nano tube packaged CuAg bimetallic catalyst Download PDF

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CN118477660B
CN118477660B CN202410947671.2A CN202410947671A CN118477660B CN 118477660 B CN118477660 B CN 118477660B CN 202410947671 A CN202410947671 A CN 202410947671A CN 118477660 B CN118477660 B CN 118477660B
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cuag
bimetallic catalyst
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nano tube
carbon nano
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CN118477660A (en
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白杰
邢泽洲
李媖
梁海欧
孙映晖
许瞳
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Inner Mongolia 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
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8926—Copper and noble metals
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/58—Fabrics or filaments
    • 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

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Abstract

The invention relates to a preparation method and application of a carbon nano tube packaged CuAg bimetallic catalyst. According to the method, a high polymer containing copper and silver bimetallic salts is dissolved as spinning solution, a hollow carbon nano tube doped with Cu and Ag is obtained by using an electrostatic spinning-vapor deposition method, and Cu nano particles are loaded outside the hollow carbon nano tube doped with Cu and silver by vapor deposition, so that the carbon nano tube loaded CuAg bimetallic catalyst is obtained. In the invention, the Ag loading amount is only 6wt%, and the yield of the glycolate is more than 90% in the glycolate preparation reaction by oxalate hydrogenation, so that the technical problems of high cost and low catalytic selectivity of the existing catalyst in the prior art are solved.

Description

Preparation method and application of carbon nano tube packaged CuAg bimetallic catalyst
Technical Field
The invention relates to the technical field of chemical catalysts, in particular to a carbon nano tube packaged CuAg bimetallic catalyst, a preparation method thereof and an application of the catalyst in a reaction for preparing glycollate by catalytic hydrogenation reaction of oxalate.
Background
Glycolate (MG) is a precursor for producing biodegradable plastic polyglycolic acid, and is also an excellent solvent for synthesizing cellulose, resins, etc. In recent years, MG supply shortage results in continuous price increase, so that development of a green sustainable MG production route is urgently needed.
Starting from coal, there is a great interest in the modern coal industry in which methyl glycolate is produced by hydrogenation of oxalate and glycolic acid is produced by hydrolysis of methyl glycolate, and thus polyglycolic acid is produced. Therefore, the realization of the efficient synthesis of the primary hydrogenation product methyl glycolate is a key and difficult point of the coal polyglycolic acid process, and is one of important directions for improving the technical economy and the market risk resistance of the coal glycol process.
Heterogeneous oxalate hydrogenation has been studied for many years, but the target product is mostly ethylene glycol, and more reports are also made on further hydrogenation of the product ethanol. The first step hydrogenation product glycolate has been regarded as a by-product and is not regarded as important. The reaction catalyst system for synthesizing glycollate by hydrogenating initial oxalate is mainly Cu-based catalyst which is favorable for preparing glycol, so that the selectivity of glycollate is poor and the reaction stability is not high. Ag has a full d outermost electron structure, and therefore has a weaker dissociation adsorption capacity for H 2 and activation energy for oxalate and glycolate than Cu. Therefore, the Ag-based catalyst is more suitable for a reaction system for preparing glycollic acid ester by hydrogenating oxalic ester than Cu.
Chinese patent No. 107442113A discloses a catalyst for preparing glycollic acid ester by hydrogenation of oxalate with Ag as main active metal, and the selectivity of the product is above 90% at 200 ℃ under Ag load of 6%. However, too high a noble metal loading has greatly limited its industrial application.
Chinese patent No. 102463122a provides a Cu-Ag/SiO 2 catalyst for oxalate hydrogenation, which has a selectivity of methyl glycolate of mostly 80% or less at 200 ℃ despite the incorporation of non-noble metals into noble metals.
Therefore, providing a catalyst with high selectivity, high stability and low noble metal usage for the reaction of preparing glycolates by oxalate hydrogenation is a problem to be solved in the art.
Disclosure of Invention
The invention aims at providing a preparation method and application of a carbon nano tube packaged CuAg bimetallic catalyst aiming at the limitation of the prior art. According to the method, a high polymer containing copper and silver bimetallic salts is dissolved as spinning solution, a Cu-Ag doped hollow carbon nano tube is obtained by using an electrostatic spinning-vapor deposition method, and Cu nano particles are loaded outside the Cu-Ag doped hollow carbon nano tube by vapor deposition, so that the carbon nano tube loaded CuAg bimetallic catalyst is obtained. In the invention, the Ag loading amount is only 6wt%, and the yield of the glycolate is more than 90% in the glycolate preparation reaction by oxalate hydrogenation, so that the technical problems of high cost and low catalytic selectivity of the existing catalyst in the prior art are solved.
In order to achieve the above object, the present invention provides the following technical solutions:
A preparation method of a carbon nano tube encapsulated CuAg bimetallic catalyst comprises the following steps:
(1) Mixing an Ag source, a first Cu source, polyacrylonitrile and N, N-dimethylformamide to obtain a mixed solution, and then carrying out electrostatic spinning to obtain polyacrylonitrile nanofiber;
Wherein, the mass ratio of Ag source to first Cu source is 4:1, a step of; 1.00 g to 2.08g (pure Cu+pure Ag) and 12.88 g to 13.14g polyacrylonitrile are added into 115 g to 118 g of N, N-dimethylformamide; the quality of pure Cu is the content of Cu in the first Cu source, and the quality of pure Ag is the content of Ag in the Ag source;
The voltage of the electrostatic spinning is 14-18 kV, and the receiving distance is 14-20 cm;
(2) Sequentially pre-oxidizing and calcining polyacrylonitrile nano fibers to obtain a Cu and Ag doped hollow carbon nano tube catalyst;
(3) And loading Cu nano particles outside the hollow carbon nano tube doped with copper and silver by vapor deposition to prepare the carbon nano tube loaded CuAg bimetallic catalyst.
The first Cu source in the step (1) is one or more of copper nitrate, copper sulfate, copper acetylacetonate and copper acetate.
The Ag source in the step (1) comprises one or two of silver nitrate and silver acetate.
In the step (2), the temperature rising rate of the pre-oxidation is 1-3 ℃/min, the temperature is 250-350 ℃ and the time is 1-4 h.
In the step (2), the temperature rising rate of calcination is 1-5 ℃/min, the temperature is 700-900 ℃ and the time is 1-4 h under the nitrogen atmosphere.
The vapor deposition of the step (3) comprises the following steps: in a double-layer frame in the reaction kettle, a Cu and Ag doped hollow carbon nano tube is placed in an upper layer, a second Cu source is placed in a lower layer, the reaction kettle is closed, vacuumizing is carried out, and then the temperature is raised to 500-600 ℃ at a speed of 1-20 ℃/min, and the temperature is kept for 1-4h.
Wherein, the mass ratio is Cu and Ag doped hollow carbon nano tube: second Cu source=1:10 to 20,
In the step (3), the second Cu source used for vapor deposition is one or both of copper chloride and cuprous chloride.
In the step (3), the temperature rising rate of the vapor deposition, the temperature rising and the calcination is 1-5 ℃/min, the temperature is 500-800 ℃, and the time is 2-6 h.
The loading amount of silver of the carbon nano tube encapsulated CuAg bimetallic catalyst is 5% -16%, the loading amount of copper is 15% -30%, and the loading amount of Cu outside the carbon nano tube is 5% -12%; the grain diameter is 200-900nm;
the carbon nano tube packaged CuAg bimetallic catalyst prepared by the method is applied to be used as a catalyst for preparing glycollate by oxalate hydrogenation.
The method specifically comprises the following steps: feeding oxalic ester and hydrogen into a fixed bed reactor filled with a carbon nano tube-packaged CuAg bimetallic catalyst, and preparing glycollic acid ester at 195-210 ℃ and 2-4 MPa;
Wherein, the mol ratio of the hydrogen to the oxalate is 60-120, and the space velocity of the oxalate is 0.5-2.5 h -1.
The invention has the substantial characteristics that:
In the prior art, the heterogeneous oxalate hydrogenation catalyst is mainly a Cu-based catalyst, so that glycol is easy to generate, and the selectivity of the catalyst to glycolate is not high. Ag has a full d outermost electron structure, and therefore has a weaker dissociation adsorption capacity for H 2 and activation energy for oxalate and glycolate than Cu. Therefore, in theory, ag-based catalysts are more suitable for the reaction system for preparing glycolates by hydrogenating oxalate than Cu.
In the invention, the elements Cu and Ag are catalytic active sites, cu and Ag can be highly dispersed by an electrostatic spinning technology, the aggregation of particles is greatly reduced, and the active sites are exposed, so that the contact between the catalytic active center and oxalate is enhanced. The metal-containing PAN film is prepared by electrospinning, and then subjected to pre-oxidation and high-temperature calcination. During the pre-oxidation, the PAN will undergo a cross-linking reaction, not only enhancing the stability of the self-structure, but also anchoring the metal in the PAN film. As the temperature increases, PAN will carbonize the film, forming Cu, ag doped hollow carbon nanotubes. In the catalyst formed in this step, the carbon nanotubes are present as amorphous carbon in elemental form, and Cu and Ag are present in oxidized state. Compared with a metal oxide catalyst directly loaded by a carbon material, the encapsulated metal can keep monovalent more after reduction treatment before reaction and is highly dispersed. In this case, a large amount of monovalent Cu and monovalent Ag are active sites for activating the carbonyl group of the reactant.
The Cu content is then further increased by vapor deposition. During vapor deposition, copper chloride sublimates and adheres to the carbon nanotube surface. After hydrogen reduction pretreatment before reaction, a large amount of Cu is converted into zero-valent Cu, and more hydrogen dissociation sites are provided.
The two steps finally obtain the copper and silver bimetallic catalysis containing both oxidation state and reduction state, and carbon exists in the form of simple substance amorphous carbon. Compared with the common load, the preparation method of the carbon nano tube encapsulated CuAg bimetallic catalyst has the advantages that copper and silver are highly dispersed, and the selectivity and the yield of glycollate can be greatly enhanced under the synergistic catalysis of the bimetallic catalyst. Ag loading is only 6wt%, and the yield of glycolate is as high as 90%.
The invention has the beneficial effects that:
according to the method for preparing the glycolate through the oxalate hydrogenation, the carbon nano tube packaged CuAg bimetallic catalyst (sample 1) is prepared through an electrostatic spinning-vapor deposition method, so that the yield of the glycolate can be effectively improved. The performance of the catalyst is superior to that of the CuAg bimetallic impregnated in a hollow carbon nano tube (comparative sample 1) and the Ag with the same metal content is encapsulated in the carbon nano tube (comparative sample 2). Under the same reaction conditions, the glycolate yield of comparative sample 1 was 63.4%, the product yield of comparative sample 2 was 72.1%, and the product yield of sample 1 was 93.4%, indicating that the amount of noble metal used in the catalyst was successfully reduced.
Drawings
Fig. 1 is an SEM image of a carbon nanotube-encapsulated CuAg bimetallic catalyst sample 1 obtained in example 1.
Fig. 2 is an SEM image of a CuAg bimetallic catalyst supported on a carbon nanotube prepared by loading Cu nanoparticles outside a hollow carbon nanotube doped with copper and silver by vapor deposition in example 1.
Detailed Description
The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1: preparation of the catalyst
Preparation of sample 1
(1) 1.57G (i.e., 7.87 mmol,0.503g Cu) of copper acetate monohydrate, 0.94g (i.e., 5.56 mmol,0.6g Ag) of silver nitrate, 12.9g of polyacrylonitrile (corresponding to a total molar amount of monomeric acrylonitrile of 243.12 mmol) and 115.95g of N, N-dimethylformamide were weighed and mixed in a conical flask, and stirred at a stirring rate of 400 rpm for 24 h to obtain a spinning solution. And (3) carrying out electrostatic spinning on the obtained precursor solution, wherein the voltage difference between the anode and the cathode is 18 kv, the distance between a spinning nozzle and an aluminum foil receiving plate is 19 cm, and collecting for a period of time to obtain the fiber membrane.
(2) The resulting fibrous membrane is then subjected to high temperature carbonization: firstly, heating to 300 ℃ at a speed of 2 ℃/min, pre-oxidizing 2h at 300 ℃, introducing nitrogen after the pre-oxidation is completed, continuously heating to 850 ℃ at a speed of 2 ℃/min under a nitrogen atmosphere, calcining 2h at 850 ℃, cooling to 200 ℃, and ending nitrogen protection, thereby obtaining the carbon nano tube containing the Cu and Ag doped double metals. An SEM image of the catalyst is shown in fig. 1. The copper content of the packaged metal is 5wt% and the silver content is 6 wt% after ICP (model Agilent 5110) test, and the copper and silver are mainly in the form of oxide.
(3) The obtained copper-silver carbon fiber (0.02 g) is placed on the upper layer of a quartz cup (a column piece is placed on the upper layer of the quartz cup, the carbon fiber is placed in the middle of the column, holes are formed below the column piece, ventilation is facilitated), and 0.25g (1.86 mmol) of copper chloride is placed on the lower layer. During the temperature rising process, the copper chloride sublimates and adheres to the carbon fiber through the vent holes of the upright posts, and the copper chloride adheres to the surface of the carbon fiber in microcosmic scale, as shown in fig. 2. The quartz cup was wrapped with aluminum foil and placed (vapor deposition furnace). The reaction vessel was closed, the gas in the reaction vessel was evacuated with a pump, the air was replaced three times with nitrogen, and finally the nitrogen was evacuated. After evacuation, the temperature was raised to 550℃at a rate of 5℃per minute, and 2h was maintained. After cooling, a carbon nanotube-encapsulated CuAg bimetallic catalyst sample 1 was obtained. The mass content of copper is 14wt% and the content of silver is 6 wt% measured by ICP (model Agilent 5110), wherein the loading of Cu outside the carbon nano tube is 9%.
Examples 2-3: preparation of samples 2-3
Under the conditions identical to those of the preparation method of the sample 1, the addition amounts of the copper acetate and the silver nitrate in the step (1) are changed from 1.57g (i.e. 7.87 mmol) of copper acetate to 0.94g (i.e. 5.56 mmol) of silver nitrate, to 2.36g (i.e. 11.81 mmol) of copper acetate+1.42 g (i.e. 8.34 mmol) of silver nitrate (sample 2), and 1.57g (i.e. 7.87 mmol) of copper acetate+1.88 g (i.e. 11.12 mmol) of silver nitrate (sample 3)
Examples 4 to 5: preparation of samples 4-5
Under the other conditions exactly the same as the preparation method of sample 1, only the copper precursor was changed to copper nitrate (sample 4) and copper acetylacetonate (sample 5) (equimolar amounts).
Preparation of comparative sample 1
The specific procedure for the sample of comparative example 1 was the same as that for sample 1 except that no copper silver metal precursor was added during electrospinning. Copper silver metal precursors are loaded on the surface of carbon nanotubes by a common dipping method, and vapor deposition is recently performed.
Preparation of control 2
The specific procedure for the sample of comparative example 2 was the same as that for sample 1 except that no copper precursor was added during electrospinning, and the molar amount of silver precursor added was equal to the total molar amount of copper and silver for this step in sample 1.
Preparation of control 3
The specific procedure for the sample in comparative example 3 was the same as for the preparation of sample 1, except that no silver precursor was added during electrospinning, and the molar amount of copper precursor added was equal to the total molar amount of copper and silver in this step in sample 1.
Example 6: reaction performance of different catalyst samples for catalyzing oxalate hydrogenation to prepare glycolate
Samples 1-5 (i.e., the products of examples 1-5) and comparative samples 1-2 were used as catalysts to evaluate their catalytic performance in a fixed bed reactor for the reaction of hydrogenation of oxalate to glycolate. And (3) taking a proper amount of catalyst raw powder, tabletting and forming, crushing, sieving, and screening out 40-60-mesh catalyst particles for subsequent reaction evaluation. After 0.5g of the catalyst was charged into the constant temperature section of a micro fixed bed reactor with an inner diameter of 8 mm, the catalyst was pretreated, at 300 ℃ under an atmosphere of H 2, 2 MPa was treated for 3H, then the mixed solution of dimethyl oxalate and methanol was heated and gasified by a micro sample pump through a preheating furnace, and mixed with H 2 into a reaction tube, and the reaction was carried out at 200 oC,2MPa,H2/dmo=80 (molar ratio), with an oxalate space velocity of 1.5H -1. And obtaining the activity and selectivity of the reaction of catalyzing the hydrogenation of the oxalate to prepare the glycolate through the sample according to the chromatographic detection result. The results after stabilization of the reaction are shown in Table 1:
from Table 1, it can be seen that the carbon nanotube supported CuAg bimetallic catalyst prepared by the invention can greatly improve the yield of glycolate through oxalate hydrogenation.
Example 7: and (3) carrying out hydrogenation on the oxalate at different reaction temperatures to obtain a glycolate reaction result.
The catalyst is evaluated as a carbon nano tube supported CuAg bimetallic catalyst sample 1, the reaction temperature is changed to 190 oC、195 oC、205o ℃, other reaction conditions are the same as those of the embodiment 1, the evaluation results of the catalyst are shown in the table 2, and it can be seen that as the reaction temperature is increased, the yield of the catalyst to the reactant methyl acetate is increased and then reduced, and the reduction is caused by excessive hydrogenation at high temperature and reduced selectivity of glycolate.
Example 8: and (3) carrying out hydrogenation on the oxalate to prepare a glycolate at different liquid hourly space velocities.
The catalyst was evaluated as a carbon nanotube-supported CuAg bimetallic catalyst sample 1, and the reactant H 2/DMO molar ratio was changed to 60, 70, 80, 90, and the other reaction conditions were the same as in example 1. The results of the catalyst evaluations are shown in Table 3, and it can be seen that higher concentrations of H 2 favor the production of glycolate.
Example 9: and (3) carrying out hydrogenation on the oxalate under different reaction pressures to obtain a glycolate reaction result.
The catalyst was evaluated as a carbon nanotube-supported CuAg bimetallic catalyst sample 1, and the reaction pressure was changed to 1 MPa, 1.5MPa, 2.0 MPa, 2.5 MPa, the feed gas composition was the same as in example 6, and the other reaction conditions were the same as in example 1. The results of the catalyst evaluation are shown in Table 4, and it can be seen that the reaction pressure was increased.
As can be seen from the above examples, the present invention provides a carbon nanotube supported CuAg bimetallic catalyst, a preparation method and application thereof, wherein a Cu source, an Ag source, polyacrylonitrile and N, N-dimethylformamide are mixed, and the obtained mixed solution is subjected to electrostatic spinning to obtain polyacrylonitrile nanofibers; then sequentially pre-oxidizing and calcining the polyacrylonitrile nanofiber to obtain a Cu and Ag doped hollow carbon nanotube catalyst; finally, cu nano particles are loaded outside the hollow carbon nano tube doped with copper and silver by vapor deposition, and the prepared carbon nano tube loads the CuAg bimetallic catalyst. The molar ratio of the Cu source to the Ag source to the polyacrylonitrile to the N, N-dimethylformamide is 3-6: 1-6: 3-7: 30-70 parts of a plastic film. The hollow ZnO nanotube catalyst provided by the invention has the advantages of simple preparation method and low cost. The carbon nano tube loaded CuAg bimetallic catalyst is used in the reaction of synthesizing glycollate by oxalic ester hydrogenation, the product yield is as high as 93.4%, and the application field of the carbon nano tube loaded CuAg bimetallic catalyst is expanded.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
The invention is not a matter of the known technology.

Claims (8)

1. The preparation method of the carbon nano tube encapsulated CuAg bimetallic catalyst is characterized by comprising the following steps:
(1) Mixing an Ag source, a first Cu source, polyacrylonitrile and N, N-dimethylformamide to obtain a mixed solution, and then carrying out electrostatic spinning to obtain polyacrylonitrile nanofiber;
Wherein, the mass ratio of Ag source to first Cu source is 4:1, a step of; 1.00 g to 2.08g of pure Cu and pure Ag and 12.88 g to 13.14g of polyacrylonitrile are added into 115 g to 118 g of N, N-dimethylformamide; the quality of pure Cu is the content of Cu in the first Cu source, and the quality of pure Ag is the content of Ag in the Ag source;
The voltage of the electrostatic spinning is 14-18 kV, and the receiving distance is 14-20 cm;
(2) Sequentially pre-oxidizing and calcining polyacrylonitrile nano fibers to obtain Cu and Ag doped hollow carbon nanotubes;
(3) And loading Cu nano particles outside the hollow carbon nano tube doped with copper and silver by vapor deposition to prepare the carbon nano tube loaded CuAg bimetallic catalyst.
2. The method for preparing a carbon nanotube-encapsulated CuAg bimetallic catalyst as claimed in claim 1, wherein the first Cu source in step (1) is one or more of copper nitrate, copper sulfate, copper acetylacetonate and copper acetate;
The Ag source in the step (1) comprises one or two of silver nitrate and silver acetate.
3. The method for preparing a carbon nanotube-encapsulated CuAg bimetallic catalyst as claimed in claim 1, wherein in the step (2), the pre-oxidation temperature rise rate is 1-3 ℃/min, the temperature is 250-350 ℃ and the time is 1-4 hours;
In the step (2), the temperature rising rate of calcination is 1-5 ℃/min, the temperature is 700-900 ℃ and the time is 1-4 h under the nitrogen atmosphere.
4. The method for preparing the carbon nanotube-encapsulated CuAg bimetallic catalyst as claimed in claim 1, wherein the vapor deposition of the step (3) comprises the steps of: placing Cu and Ag doped hollow carbon nanotubes in the double-layer frame in the reaction kettle, placing a second Cu source in the upper layer, sealing the reaction kettle, vacuumizing, heating to 500-600 ℃ at a speed of 1-20 ℃/min, and keeping for 1-4 h;
Wherein, the mass ratio is Cu and Ag doped hollow carbon nano tube: second Cu source=1:10-20.
5. The method of preparing a CuAg bimetallic catalyst encapsulated by carbon nanotubes as claimed in claim 4, wherein in the step (3), the second Cu source used for vapor deposition is one or both of copper chloride and cuprous chloride.
6. The preparation method of the carbon nanotube-encapsulated CuAg bimetallic catalyst according to claim 1, which is characterized in that the silver loading of the carbon nanotube-encapsulated CuAg bimetallic catalyst is 5% -16%, the copper loading is 15% -30%, and the Cu loading outside the carbon nanotubes is 5% -12%; the grain diameter is 200-900nm.
7. The use of the carbon nanotube-encapsulated CuAg bimetallic catalyst prepared by the method of claim 1, as a catalyst for the hydrogenation of oxalate to glycolate.
8. The use according to claim 7, characterized by the steps of: feeding oxalic ester and hydrogen into a fixed bed reactor filled with a carbon nano tube-packaged CuAg bimetallic catalyst, and preparing glycollic acid ester at 195-210 ℃ and 2-4 MPa;
Wherein, the mol ratio of the hydrogen to the oxalate is 60-120, and the space velocity of the oxalate is 0.5-2.5 h -1.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102553615A (en) * 2012-01-18 2012-07-11 厦门大学 Oxalate hydrogenation copper-gold dual-metal catalyst and preparation method thereof
CN107469825A (en) * 2017-08-25 2017-12-15 湘潭大学 A kind of preparation method and application of the nickel-based multimetallic catalyst of the carbon nanotube loaded bimetallic copper magnesium codope of oxidation modification

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114950454B (en) * 2022-06-09 2023-03-24 苏州大学 Catalyst for preparing ethylene glycol by dimethyl oxalate hydrogenation and preparation method thereof
CN118106009A (en) * 2024-02-05 2024-05-31 天津大学 Carbon-nitrogen doped mesoporous silica supported copper-based catalyst for ester hydrogenation and preparation method and use method thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102553615A (en) * 2012-01-18 2012-07-11 厦门大学 Oxalate hydrogenation copper-gold dual-metal catalyst and preparation method thereof
CN107469825A (en) * 2017-08-25 2017-12-15 湘潭大学 A kind of preparation method and application of the nickel-based multimetallic catalyst of the carbon nanotube loaded bimetallic copper magnesium codope of oxidation modification

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