CN113231076A - Palladium-copper catalyst and preparation method and application thereof - Google Patents
Palladium-copper catalyst and preparation method and application thereof Download PDFInfo
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- 239000010949 copper Substances 0.000 title claims abstract description 135
- 239000003054 catalyst Substances 0.000 title claims abstract description 119
- 238000002360 preparation method Methods 0.000 title claims abstract description 45
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims abstract description 236
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 117
- 239000002105 nanoparticle Substances 0.000 claims abstract description 90
- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical compound O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 claims abstract description 80
- 239000013084 copper-based metal-organic framework Substances 0.000 claims abstract description 58
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 45
- 150000001879 copper Chemical class 0.000 claims abstract description 36
- QMKYBPDZANOJGF-UHFFFAOYSA-N benzene-1,3,5-tricarboxylic acid Chemical compound OC(=O)C1=CC(C(O)=O)=CC(C(O)=O)=C1 QMKYBPDZANOJGF-UHFFFAOYSA-N 0.000 claims abstract description 34
- YJVFFLUZDVXJQI-UHFFFAOYSA-L palladium(ii) acetate Chemical compound [Pd+2].CC([O-])=O.CC([O-])=O YJVFFLUZDVXJQI-UHFFFAOYSA-L 0.000 claims abstract description 28
- 239000000243 solution Substances 0.000 claims abstract description 28
- 238000004729 solvothermal method Methods 0.000 claims abstract description 24
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 claims abstract description 23
- 239000007864 aqueous solution Substances 0.000 claims abstract description 18
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 8
- 239000012298 atmosphere Substances 0.000 claims abstract description 4
- 239000011261 inert gas Substances 0.000 claims abstract description 4
- 238000002156 mixing Methods 0.000 claims abstract description 4
- XPFVYQJUAUNWIW-UHFFFAOYSA-N furfuryl alcohol Chemical compound OCC1=CC=CO1 XPFVYQJUAUNWIW-UHFFFAOYSA-N 0.000 claims description 90
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 49
- 238000010438 heat treatment Methods 0.000 claims description 47
- 238000000034 method Methods 0.000 claims description 33
- 239000003575 carbonaceous material Substances 0.000 claims description 29
- SXTLQDJHRPXDSB-UHFFFAOYSA-N copper;dinitrate;trihydrate Chemical compound O.O.O.[Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O SXTLQDJHRPXDSB-UHFFFAOYSA-N 0.000 claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 238000009210 therapy by ultrasound Methods 0.000 claims description 14
- 229910052751 metal Inorganic materials 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 7
- 238000010304 firing Methods 0.000 claims description 4
- 238000009903 catalytic hydrogenation reaction Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 3
- 230000003197 catalytic effect Effects 0.000 abstract description 25
- 239000003638 chemical reducing agent Substances 0.000 abstract description 8
- 238000006243 chemical reaction Methods 0.000 description 29
- 230000000052 comparative effect Effects 0.000 description 19
- 238000006722 reduction reaction Methods 0.000 description 15
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- 238000005984 hydrogenation reaction Methods 0.000 description 13
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- 239000002245 particle Substances 0.000 description 11
- 230000008569 process Effects 0.000 description 10
- 230000000694 effects Effects 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 6
- 238000001291 vacuum drying Methods 0.000 description 6
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 5
- 229910001431 copper ion Inorganic materials 0.000 description 5
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- 229910021641 deionized water Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 238000001027 hydrothermal synthesis Methods 0.000 description 3
- 238000005470 impregnation Methods 0.000 description 3
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- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
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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
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
- C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D307/38—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms
- C07D307/40—Radicals substituted by oxygen atoms
- C07D307/42—Singly bound oxygen atoms
- C07D307/44—Furfuryl alcohol
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- Chemical Kinetics & Catalysis (AREA)
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Abstract
The application relates to the technical field of catalysts, in particular to a palladium-copper catalyst and a preparation method and application thereof. The preparation method of the palladium-copper catalyst comprises the following steps: preparing palladium nanoparticles: dissolving palladium acetate in absolute ethyl alcohol, and treating at a constant temperature of 0-20 ℃ for 24-48 hours to obtain an absolute ethyl alcohol solution containing palladium nanoparticles; preparing a palladium-modified copper-based metal organic framework: dissolving trimesic acid in the absolute ethanol solution containing the palladium nanoparticles, adding a copper nitrate aqueous solution, uniformly mixing, and carrying out a solvothermal reaction to obtain a palladium-modified copper-based metal organic framework; roasting: and roasting the palladium-modified copper-based metal organic framework in an inert gas atmosphere to obtain the palladium-copper catalyst taking porous carbon as a carrier. The preparation method can obtain the palladium-copper catalyst with good catalytic activity on furfural, has simple steps, does not need to additionally use a reducing agent, and has good industrial application prospect.
Description
Technical Field
The application relates to the technical field of catalysts, in particular to a palladium-copper catalyst and a preparation method and application thereof.
Background
The preparation of furfuryl alcohol by catalytic hydrogenation of furfural is an important chemical production process, and the catalyst used in the current furfural hydrogenation is mainly a supported copper-based catalyst. However, the catalytic activity of the common copper-based catalyst is general, and it is necessary to develop a new catalyst to improve the furfural catalytic capability. Moreover, the preparation method of the modified copper-based catalyst often needs complicated steps or a reducing agent needs to be introduced, so that the industrial popularization and application of the copper-based catalyst are limited to a certain extent.
Disclosure of Invention
The application aims to provide a palladium-copper catalyst, and a preparation method and application thereof, so as to solve the problems of low catalytic activity, complex preparation method and the like of the existing supported copper-based catalyst.
In a first aspect, the present application provides a method for preparing a palladium-copper catalyst, comprising the steps of:
preparing palladium nanoparticles: dissolving palladium acetate in absolute ethyl alcohol, and treating at a constant temperature of 0-20 ℃ for 24-48 hours to obtain an absolute ethyl alcohol solution containing palladium nanoparticles;
preparing a palladium-modified copper-based metal organic framework: dissolving trimesic acid in the absolute ethanol solution containing the palladium nanoparticles, adding a copper nitrate aqueous solution, uniformly mixing, and carrying out a solvothermal reaction to obtain a palladium-modified copper-based metal organic framework;
roasting: and roasting the palladium-modified copper-based metal organic framework in an inert gas atmosphere to obtain the palladium-copper catalyst taking porous carbon as a carrier.
Preferably, in the step of preparing palladium nanoparticles, the isothermal treatment conditions are as follows: the mixture is processed for 30 to 48 hours at a constant temperature of 0 to 10 ℃.
Further, the step of preparing the palladium nanoparticle is as follows: the palladium acetate was added to the absolute ethanol, and subjected to ultrasonic treatment at 0 ℃ for 10 minutes and further to constant temperature treatment at 0 ℃ for 48 hours.
Further, in the step of preparing the palladium-modified copper-based metal organic framework, the conditions of the solvothermal reaction are as follows: heating from room temperature to 80-100 ℃ at a heating rate of 0.15-0.3 ℃/min, keeping the temperature for 10-15 hours at the temperature of 80-100 ℃, heating to 110-130 ℃ at a heating rate of 0.15-0.3 ℃/min, and keeping the temperature for 24-48 hours at the temperature of 110-130 ℃.
Further, in the step of preparing the palladium-modified copper-based metal organic framework, the conditions of the solvothermal reaction are as follows: the temperature is raised from room temperature to 80 ℃ at the heating rate of 0.2 ℃/minute, the temperature is kept constant at the temperature of 80 ℃ for 12 hours, then the temperature is raised to 110 ℃ at the heating rate of 0.2 ℃/minute, and the temperature is kept constant at the temperature of 110 ℃ for 24 hours.
Further, in the step of preparing the palladium-modified copper-based metal organic framework, after the solvothermal reaction, carrying out suction filtration, absolute ethyl alcohol washing and vacuum drying on a solid product obtained by the solvothermal reaction to obtain the palladium-modified copper-based metal organic framework.
Further, in the preparation method, the copper nitrate aqueous solution is obtained by dissolving copper nitrate trihydrate in water, the molar ratio of palladium acetate to copper nitrate trihydrate is 0.5: 100-1.5: 100, and the molar ratio of copper nitrate trihydrate to trimesic acid is 1: 1-2: 1; the volume ratio of the absolute ethyl alcohol to the water in the copper nitrate aqueous solution is 1: 0.8-1: 1.5; in the copper nitrate aqueous solution, the dosage ratio of the copper nitrate trihydrate to the water is 1mmol:10 mL-2 mmol:10 mL.
Further, the roasting step is as follows: and heating the palladium-modified copper-based metal organic frame to 400-500 ℃ at a speed of 2-3 ℃/min, and roasting at a constant temperature of 400-500 ℃ for 2-3 hours to obtain the palladium-copper catalyst.
In a second aspect, the present application provides a palladium-copper catalyst prepared by the preparation method described above in the first aspect.
Further, the palladium-copper catalyst comprises a porous carbon material carrier, copper nanoparticles coated inside the porous carbon material carrier, and palladium nanoparticles coated inside the porous carbon material carrier.
In a third aspect, the present application provides a use of the palladium-copper catalyst according to the second aspect for catalyzing furfural hydrogenation to produce furfuryl alcohol.
Compared with the prior art, the method has the following beneficial effects:
according to the preparation method, the palladium-copper catalyst with good catalytic activity on furfural can be obtained by researching and developing a novel preparation method of the palladium-copper catalyst, and the preparation method is simple in step, does not need to additionally use a reducing agent, and has a good industrial application prospect. Specifically, firstly, divalent palladium ions are reduced to zero-valent palladium by low-temperature self-reduction, and the palladium nanoparticles having a small particle size are formed by controlling the low temperature and the reduction time. And then, directly carrying out solvothermal reaction on the palladium nanoparticles, trimesic acid and copper nitrate to generate the copper-based metal organic framework doped with palladium, wherein the palladium is not simply attached to the outer surfaces of pores of the copper-based metal organic framework, but is dispersed in the copper-based metal organic framework along with the crystal growth of the metal organic framework. And finally, carrying out high-temperature roasting on the copper-based metal organic framework modified by the palladium nanoparticles to enable the copper-based metal organic framework to generate a high-temperature carbothermic reduction reaction, so that the metal organic framework in the original crystal structure is converted into a porous carbon material carrier, copper ions originally combined with the organic ligand are reduced into zero-valent copper nanoparticles, the palladium nanoparticles still keep the zero-valent nanoparticle state, and finally the palladium-copper catalyst taking the porous carbon material as the carrier and coated with the copper nanoparticles and the palladium nanoparticles in the carrier is obtained.
That is to say, the invention concepts of low-temperature self-reduction of divalent palladium ions, direct participation of zero-valent palladium nanoparticles in generation of a copper-based metal organic framework and high-temperature carbon thermal reduction of the copper-based metal organic framework really achieve the purpose that no additional reducing reagent or hydrogen is needed in the preparation process of the palladium-copper catalyst, and meanwhile, the steps also enable the whole preparation process to be simple and uncomplicated.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is an XRD pattern of palladium nanoparticles prepared in a preparation method of example two of the present application;
FIG. 2 is an XRD pattern of a palladium-modified copper-based metal organic framework prepared in a preparation method according to example two of the present application;
FIG. 3 is an XRD pattern of a palladium copper catalyst of example two of the present application;
FIG. 4 is an XPS plot of palladium element in a palladium copper catalyst according to example II of the present application;
FIG. 5 is an XPS plot of copper element for a palladium copper catalyst according to example two of the present application;
FIG. 6 is an SEM image of a palladium-modified copper-based metal organic framework prepared in a preparation method of example II of the present application;
FIG. 7 is an SEM image of a palladium-copper catalyst of example two herein;
fig. 8 is a graph showing the results of the test of the cycle stability of the examples of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that the terms "comprises" and "comprising," and any variations thereof, in the embodiments of the present application, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The technical solution of the present application will be further explained with reference to the following embodiments and the accompanying drawings.
The embodiment of the application provides a palladium-copper catalyst and a preparation method thereof, and the preparation method of the palladium-copper catalyst comprises the following steps:
preparing palladium nanoparticles: dissolving palladium acetate in absolute ethyl alcohol, and treating at a constant temperature of 0-20 ℃ for 24-48 hours to obtain an absolute ethyl alcohol solution containing palladium nanoparticles;
preparing a palladium-modified copper-based metal organic framework: dissolving trimesic acid in the absolute ethanol solution containing the palladium nanoparticles, adding a copper nitrate aqueous solution, uniformly mixing, and carrying out a solvothermal reaction to obtain a palladium-modified copper-based metal organic framework;
roasting: and roasting the palladium-modified copper-based metal organic framework in an inert gas atmosphere to obtain the palladium-copper catalyst taking porous carbon as a carrier.
The preparation method provided by the embodiment of the application has at least the following advantages in the technical field of preparation methods of copper-based catalysts modified with palladium:
the process method is simplified, and the catalyst can be loaded with the palladium nano particles and the copper nano particles with zero valence without using any external reducing agent.
On the one hand, in the related art, to obtain the zero-valent palladium nanoparticles, it is usually necessary to use a reducing agent or hydrogen to obtain the zero-valent metallic palladium, but the inventors of the present application have surprisingly found that when palladium acetate is subjected to a constant temperature treatment under a relatively low temperature condition, the palladium acetate itself can undergo a reduction reaction to gradually reduce the palladium to the zero-valent metallic palladium even without using an additional reducing agent. Furthermore, observation and experiment show that palladium does not rapidly precipitate as a pile under a specific condition of constant temperature treatment at 0-20 ℃ for 24-48 hours, but is dispersed in absolute ethyl alcohol as fine particles to form a suspension. After the constant temperature treatment, the absolute ethyl alcohol solution is subjected to centrifugal separation, obvious precipitate and clear upper layer solution can also be obtained, and the precipitate is taken for component analysis to prove that the precipitate is zero-valent metal palladium, so that the suspension of palladium nanoparticles fully dispersed in the absolute ethyl alcohol solution can be further proved under the specific conditions.
On the other hand, on the basis of conveniently obtaining the zero-valent palladium nano particles through low-temperature self-reduction operation, the zero-valent palladium nano particles are directly used in the step of growing the copper-based metal organic framework crystal, so that copper ions are combined with organic ligands to grow into the metal organic framework crystal, and the zero-valent palladium nano particles are also coated in the metal organic framework. Then carrying out high-temperature carbothermic reduction on the copper-based metal organic framework in the special palladium-doped form, so that the metal organic framework is pyrolyzed into a porous carbon material, and copper ions are reduced into zero-valent copper nanoparticles by using carbon as a reducing agent. Therefore, although palladium and copper in the palladium-copper catalyst exist in the structural form of zero-valent nanoparticles, no additional reducing agent is needed in the whole preparation process, the reagent dosage is reduced, the preparation idea is optimized, the whole preparation method is simplified, and the industrial popularization and application are easy to carry out.
Secondly, the distribution state of palladium and copper active substances of the palladium-copper catalyst obtained by the preparation method of the embodiment of the application is optimized, so that the catalytic performance is promoted to be optimized.
When the impregnation method is adopted to load palladium on the copper-based catalyst, the palladium can only be loaded on the pore surfaces of the porous carrier material, or the palladium can only be loaded on the surface of the metal organic framework, so that the contact of the palladium and the copper components is less, the interaction between the palladium and the copper components is weaker, and palladium particles are easy to agglomerate and grow during high-temperature roasting and are not beneficial to catalysis. However, in the preparation method of the embodiment of the present application, as described above, the palladium nanoparticles generated by self-reduction are coated in the metal-organic framework along with the growth of the copper-based metal-organic framework crystal, so that in the high-temperature calcination step, the palladium and copper components have more contact opportunities, and a palladium-copper structure is more easily formed, and because the palladium nanoparticles are coated in the metal-organic framework, the palladium nanoparticles have better high-temperature thermal stability and are not easy to agglomerate. Therefore, the palladium nanoparticles and the copper nanoparticles obtained by the preparation method of the embodiment of the application are coated in the porous carbon material carrier (the carrier is obtained by pyrolyzing the metal organic framework), and the palladium-copper structure is easier to form, the dispersibility of the nanoparticles is better, and the nanoparticles are not easy to agglomerate at high temperature, so that the catalytic performance of the palladium-copper catalyst can be improved.
Wherein the constant temperature treatment at 0-20 ℃ includes any point in the temperature range, for example, the constant temperature treatment temperature is 0 ℃, 5 ℃, 10 ℃, 15 ℃ or 20 ℃, and the constant temperature treatment time is 24-48 hours, including any point in the time range, for example, the constant temperature treatment time is 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours or 48 hours.
Preferably, in the step of preparing palladium nanoparticles, the isothermal treatment conditions are as follows: the mixture is processed for 30 to 48 hours at a constant temperature of 0 to 10 ℃.
After the inventor of the application carries out multiple groups of experimental tests, the temperature of the palladium acetate self-reduction is controlled to be constant at 0-10 ℃ for 30-48 hours, and the finally obtained palladium-copper catalyst has better catalytic activity.
Further, the step of preparing the palladium nanoparticle is as follows: the palladium acetate was added to the absolute ethanol, and subjected to ultrasonic treatment at 0 ℃ for 10 minutes and further to constant temperature treatment at 0 ℃ for 48 hours.
Furthermore, the inventors of the present application have found that when the temperature is controlled at 0 ℃ for a constant temperature treatment for 48 hours, the obtained palladium-copper catalyst has better catalytic performance.
Further, in the step of preparing the palladium-modified copper-based metal organic framework, the conditions of the solvothermal reaction are as follows: heating from room temperature to 80-100 ℃ at a heating rate of 0.15-0.3 ℃/min, keeping the temperature for 10-15 hours at the temperature of 80-100 ℃, heating to 110-130 ℃ at a heating rate of 0.15-0.3 ℃/min, and keeping the temperature for 24-48 hours at the temperature of 110-130 ℃.
In the process of preparing the palladium-modified copper-based metal organic framework, the temperature rise of the solvent heat treatment condition is controlled in stages, the temperature is raised to be lower 80-100 ℃ and is kept constant for 10-15 hours under the condition, and then the temperature is further raised to be higher 110-130 ℃ and is kept constant for 45-50 hours under the condition. Through the heat treatment of a solvent with the temperature controlled by stages, at the initial stage of the crystallization process, the divalent copper ions and the trimesic acid carry out self-assembly coordination reaction to form nano-scale metal organic framework material small crystal particles; then, orderly assembling the crystals to form the metal organic framework material with a regular shape; the temperature of solvent heat treatment is further raised, and the framework structure is gradually repaired and perfected under the Ostwald curing effect, so that a perfect metal organic framework crystal material is grown. This is obviously different from the method of directly heating to a specified temperature in one step when performing solvothermal treatment in the related art, and the direct heating mode is difficult to form nano-scale metal organic framework material small crystal particles due to the high initial solvothermal treatment temperature, and finally results in the formation of a metal organic framework with large particle size, which is in great difference with the small particle size metal organic framework that is finally desired to be obtained in the present application. By optimizing the solvent heat treatment conditions, the crystal volume of the copper-based metal organic framework can be reasonably controlled, so that the method is favorable for improving the related performance of the subsequent preparation of the magnetic catalyst.
Wherein the temperature rise rate is 0.15-0.3 ℃/min inclusive of any point within the rate range, such as 0.15 ℃/min, 0.18 ℃/min, 0.2 ℃/min, 0.22 ℃/min, 0.25 ℃/min, 0.28 ℃/min, or 0.3 ℃/min. The constant temperature of 10 to 15 hours includes any point value within the time range, for example, constant temperature of 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or 15 hours. The temperature is raised to 80-100 ℃ including any point in the temperature range, such as 80 ℃, 85 ℃, 90 ℃, 95 ℃ or 100 ℃. The constant temperature is kept for 24-48 hours, and any point value in the time range is included, such as 24 hours, 30 hours, 36 hours, 42 hours or 48 hours. The temperature is raised to 110-130 ℃ including any point in the temperature range, such as 110 ℃, 115 ℃, 118 ℃, 120 ℃, 122 ℃, 125 ℃, 128 ℃ or 130 ℃.
Further, in the step of preparing the palladium-modified copper-based metal organic framework, the conditions of the solvothermal reaction are as follows: the temperature is raised from room temperature to 80 ℃ at the heating rate of 0.2 ℃/minute, the temperature is kept constant at the temperature of 80 ℃ for 12 hours, then the temperature is raised to 110 ℃ at the heating rate of 0.2 ℃/minute, and the temperature is kept constant at the temperature of 110 ℃ for 24 hours.
After a series of experimental tests, the inventor finds that the solvent heat treatment condition is a better condition for obtaining an ideal crystal structure and volume, and the palladium-copper catalyst finally obtained by using the copper-based metal organic framework generated under the condition has remarkable characteristics of nanoparticles, and has better catalytic performance and stable cycle performance.
Further, in the step of preparing the palladium-modified copper-based metal organic framework, after the solvothermal reaction, carrying out suction filtration, absolute ethyl alcohol washing and vacuum drying on a solid product obtained by the solvothermal reaction to obtain the palladium-modified copper-based metal organic framework.
Further, the copper nitrate aqueous solution is obtained by dissolving copper nitrate trihydrate in water, wherein the molar ratio of palladium acetate to copper nitrate trihydrate is 0.5: 100-1.5: 100, and the molar ratio of copper nitrate trihydrate to trimesic acid is 1: 1-1: 2; the volume ratio of the absolute ethyl alcohol to the water in the copper nitrate aqueous solution is 1: 0.8-1: 1.5; in the copper nitrate aqueous solution, the dosage ratio of the copper nitrate trihydrate to the water is 1mmol:10 mL-2 mmol:10 mL.
The material ratio can obtain a copper-based metal organic framework structure loaded with a proper amount of palladium nano particles, and is favorable for obtaining a palladium-copper catalyst with better catalytic performance.
Wherein the molar ratio of palladium acetate to copper nitrate trihydrate is from 0.5:100 to 1.5:100 inclusive, for example, the molar ratio of palladium acetate to copper nitrate trihydrate is 0.5:100, 0.8:100, 1:100, 1.2:100, or 1.5: 100. The molar ratio of copper nitrate trihydrate to trimesic acid is from 1:1 to 2:1, including any point within the range, for example, a molar ratio of copper nitrate trihydrate to trimesic acid of 1:1, 1.2:1, 1.5:1, 1.8:1, or 2: 1. The volume ratio of the absolute ethyl alcohol to the water in the aqueous copper nitrate solution is 1:0.8 to 1:1.5 inclusive of any point within the range of the volume ratio, for example, the volume ratio of the absolute ethyl alcohol to the water in the aqueous copper nitrate solution is 1:0.8, 1:1, 1:1.2, or 1: 1.5. The amount ratio of copper nitrate trihydrate to water in the aqueous copper nitrate solution is 1mmol:10 mL-2 mmol:10mL inclusive, for example, 1mmol:10mL, 1.2mmol:10mL, 1.5mmol:10mL, 1.8mmol:10mL, or 2mmol:10 mL.
Further, the roasting step is as follows: and heating the palladium-modified copper-based metal organic frame to 400-500 ℃ at a speed of 2-3 ℃/min, and roasting at a constant temperature of 400-500 ℃ for 2-3 hours to obtain the palladium-copper catalyst.
In the application, the copper-based metal organic framework modified by palladium is subjected to high-temperature pyrolysis carbonization reaction and carbon thermal reduction reaction under the roasting condition, the metal organic framework is subjected to carbon decomposition to form a porous carbon material carrier, divalent copper ions are reduced to form zero-valent copper nanoparticles, and the palladium nanoparticles are kept unchanged, so that the copper nanoparticles and the palladium nanoparticles are coated in the porous carbon material carrier, and are not only loaded on the pore surface of the porous carbon material carrier. The palladium-copper catalyst structure has better catalytic activity and stable cycle performance for the application of furfural in preparing furfuryl alcohol.
Wherein the temperature rise rate is 2-3 ℃/min and includes any value in the numerical range, for example, the temperature rise rate is 2 ℃/min, 2.2 ℃/min, 2.5 ℃/min, 2.8 ℃/min or 3 ℃/min. The firing temperature is 400 to 500 ℃ inclusive, and may be 400 ℃, 420 ℃, 450 ℃, 480 ℃, or 500 ℃. The constant-temperature roasting time is 2 to 3 hours including any value in the time range, for example, the constant-temperature roasting time is 2 hours, 2.2 hours, 2.5 hours, 2.8 hours or 3 hours.
In a second aspect, the present application provides a palladium-copper catalyst prepared by the preparation method described above in the first aspect.
Further, the palladium-copper catalyst comprises a porous carbon material carrier, copper nanoparticles coated inside the porous carbon material carrier, and palladium nanoparticles coated inside the porous carbon material carrier.
Because the palladium nano particles are coated in the copper-based metal organic framework in the process of loading the palladium nano particles on the copper-based metal organic framework, the palladium nano particles are coated in the porous carbon material carrier instead of only the surfaces of pores after roasting, the structure is firstly stable, the palladium nano particles cannot agglomerate in the high-temperature roasting process, and secondly, the palladium nano particles are loaded in the porous carbon material carrier stably, so that the condition that a palladium-copper catalyst is greatly lost along with the centrifugal action in the subsequent centrifugal cycle use process can be avoided, and the problem that the catalytic activity of the palladium-copper catalyst is rapidly reduced along with the cycle use can be avoided.
In a third aspect, the present application provides a use of the palladium-copper catalyst according to the second aspect for catalyzing furfural hydrogenation to produce furfuryl alcohol.
As described above, when furfural hydrogenation is performed to prepare furfuryl alcohol by using the palladium-copper catalyst of the present application, due to the special structure of the palladium-copper catalyst, the palladium-copper catalyst has higher catalytic reaction activity, and finally, the conversion rate of furfural and the selectivity of furfuryl alcohol are both high. In addition, the palladium-copper catalyst has high cycle stability, which indicates that the palladium nanoparticles and the copper nanoparticles are coated in the porous carbon material carrier, so that the load stability of the catalyst can be ensured, and more loss can not occur in the centrifugal recycling process.
In order to explain the technical scheme and technical effect of the present application in more detail, the present application will be explained by more specific examples and comparative examples.
Example one
This example provides a palladium-copper catalyst, and the preparation method of the palladium-copper catalyst includes the following steps:
preparing palladium nanoparticles: dissolving 0.0085mmol of palladium acetate in 10mL of absolute ethyl alcohol, performing ultrasonic treatment for 10 minutes at 0 ℃, and then performing constant-temperature treatment for 48 hours at 0 ℃ to obtain an absolute ethyl alcohol solution containing palladium nanoparticles;
preparing a palladium-modified copper-based metal organic framework: dissolving 1mmol of trimesic acid in the absolute ethyl alcohol solution containing the palladium nanoparticles, and performing ultrasonic treatment for 10 minutes at room temperature; weighing 1.7mmol of copper nitrate trihydrate, dissolving the copper nitrate trihydrate in 10mL of deionized water to form a copper nitrate aqueous solution, adding the copper nitrate aqueous solution into an anhydrous ethanol solution containing palladium nanoparticles dissolved with trimesic acid, stirring uniformly, continuing ultrasonic treatment for 20 minutes to mix uniformly, pouring the mixed solution into a hydrothermal synthesis reaction kettle for solvothermal reaction, wherein the solvothermal reaction conditions are as follows: heating the mixture from room temperature to 80 ℃ at a heating rate of 0.2 ℃/min, keeping the temperature constant at the temperature of 80 ℃ for 12 hours, heating the mixture to 110 ℃ at a heating rate of 0.2 ℃/min, keeping the temperature constant at the temperature of 110 ℃ for 48 hours, carrying out suction filtration and absolute ethyl alcohol washing on the obtained solid product for 5 times, and carrying out vacuum drying at 60 ℃ for 6 hours to obtain a palladium-modified copper-based metal organic framework;
roasting: and placing the copper-based metal organic framework modified by palladium in a constant-temperature area of a tubular furnace, heating to 400 ℃ at the speed of 2 ℃/min in a nitrogen atmosphere, and roasting at the constant temperature of 400 ℃ for 2 hours to obtain the palladium-copper catalyst.
The palladium-copper catalyst prepared by the preparation method comprises a porous carbon material carrier, copper nanoparticles and palladium nanoparticles, wherein the copper nanoparticles and the palladium nanoparticles are coated in the porous carbon material carrier.
Example two
This example differs from example one only in that, in the step of preparing palladium nanoparticles, 0.017mol of palladium acetate was weighed and dissolved in 10mL of anhydrous ethanol.
EXAMPLE III
This example differs from example one only in that, in the step of preparing palladium nanoparticles, 0.0255mol of palladium acetate was weighed and dissolved in 10mL of anhydrous ethanol.
Example four
This example is different from the second example only in that, in the step of preparing palladium nanoparticles, palladium acetate is subjected to ultrasonic treatment at 0 ℃ to dissolve and uniformly disperse the palladium acetate in absolute ethyl alcohol, and then is subjected to constant temperature treatment at 20 ℃ for 24 hours to obtain an absolute ethyl alcohol solution containing palladium nanoparticles.
EXAMPLE five
This example differs from example two only in that in the step of preparing a palladium-modified copper-based metal organic framework, the conditions of the solvothermal reaction are: the temperature is raised from room temperature to 100 ℃ at the heating rate of 0.2 ℃/min, the temperature is kept constant at the temperature of 100 ℃ for 12 hours, then the temperature is raised to 130 ℃ at the heating rate of 0.2 ℃/min, and the temperature is kept constant at the temperature of 130 ℃ for 24 hours.
EXAMPLE six
This example differs from example two only in that, in the firing step, the firing temperature is 500 ℃.
EXAMPLE seven
This example differs from example two only in that in the step of preparing a palladium-modified copper-based metal organic framework, the conditions of the solvothermal reaction are: the temperature is raised from room temperature to 90 ℃ at the heating rate of 0.15 ℃/minute, the temperature is kept constant at the temperature of 90 ℃ for 15 hours, then the temperature is raised to 115 ℃ at the heating rate of 0.15 ℃/minute, and the temperature is kept constant at the temperature of 115 ℃ for 30 hours.
Comparative example 1
The present comparative example provides a copper catalyst, the preparation method of which comprises the steps of:
dissolving 1mmol of trimesic acid in 10mL of absolute ethyl alcohol, and performing ultrasonic treatment for 10 minutes at room temperature; weighing 1.7mmol of copper nitrate trihydrate, dissolving the copper nitrate trihydrate in 10mL of deionized water to form a copper nitrate aqueous solution, adding the copper nitrate aqueous solution into an absolute ethyl alcohol solution dissolved with trimesic acid, continuing ultrasonic treatment for 20 minutes after uniformly stirring to fully and uniformly mix, then pouring the mixed solution into a hydrothermal synthesis reaction kettle for solvothermal reaction, wherein the solvothermal reaction conditions are as follows: heating from room temperature to 80 ℃ at a heating rate of 0.2 ℃/min, keeping the temperature constant at the temperature of 80 ℃ for 12 hours, heating to 110 ℃ at a heating rate of 0.2 ℃/min, keeping the temperature constant at the temperature of 110 ℃ for 48 hours, carrying out suction filtration and absolute ethyl alcohol washing on a solid product, and carrying out vacuum drying at 60 ℃ for 6 hours to obtain a copper-based metal organic frame;
roasting: and (2) placing the copper-based metal organic frame in a tubular furnace constant-temperature area, heating to 400 ℃ at the speed of 2 ℃/min in a nitrogen atmosphere, and roasting at the constant temperature of 400 ℃ for 2 hours to obtain the copper catalyst, wherein the copper catalyst is specifically copper loaded on a porous carbon material carrier.
Comparative example No. two
The present comparative example provides a palladium-copper catalyst, the preparation method of which comprises the steps of:
preparing a copper-based metal organic framework: dissolving 1mmol of trimesic acid in 10mL of absolute ethyl alcohol, and performing ultrasonic treatment for 10 minutes at room temperature; weighing 1.7mmol of copper nitrate trihydrate, dissolving the copper nitrate trihydrate in 10mL of deionized water to form a copper nitrate aqueous solution, adding the copper nitrate aqueous solution into an absolute ethyl alcohol solution dissolved with trimesic acid, continuing ultrasonic treatment for 20 minutes after uniformly stirring to fully and uniformly mix, then pouring the mixed solution into a hydrothermal synthesis reaction kettle for solvothermal reaction, wherein the solvothermal reaction conditions are as follows: heating from room temperature to 80 ℃ at a heating rate of 0.2 ℃/min, keeping the temperature constant at the temperature of 80 ℃ for 12 hours, heating to 110 ℃ at a heating rate of 0.2 ℃/min, keeping the temperature constant at the temperature of 110 ℃ for 48 hours, carrying out suction filtration and absolute ethyl alcohol washing on a solid product, and carrying out vacuum drying at 60 ℃ for 6 hours to obtain a copper-based metal organic frame;
dipping: dissolving 0.017mmol of palladium acetate in 10mL of absolute ethyl alcohol, performing ultrasonic treatment at 0 ℃ for 10 minutes, then soaking the solution in the copper-based metal organic framework, performing ultrasonic treatment at 0 ℃ for 20 minutes, and performing vacuum drying at 40 ℃ for 6 hours to obtain the copper-based metal organic framework loaded with palladium;
roasting: and (3) drying the copper-based metal organic framework loaded with palladium in vacuum, then placing the framework in a tubular furnace constant-temperature area, heating to 400 ℃ at the speed of 2 ℃/min in a nitrogen atmosphere, and roasting at the constant temperature of 400 ℃ for 2 hours to obtain the palladium-copper catalyst.
The palladium-copper catalyst prepared by the preparation method comprises a porous carbon material carrier, copper nanoparticles and palladium particles, wherein the copper nanoparticles are coated in the porous carbon material carrier, and the palladium particles are attached to the pore surfaces of the porous carbon material carrier.
Comparative example No. three
The comparative example is different from the second example only in that in the step of preparing the palladium nanoparticles, 0.017mmol of palladium acetate is dissolved in 10mL of absolute ethyl alcohol, ultrasonic treatment is carried out at 0 ℃ for 10 minutes, and then constant temperature treatment is carried out at 30 ℃ for 48 hours to obtain an absolute ethyl alcohol solution containing palladium precipitates.
In the present comparative example, when the isothermal treatment was carried out at 30 ℃, the inventors found that much precipitation occurred rapidly in the absolute ethanol solution, instead of the fine particles suspended in the absolute ethanol solution. It can be seen that, even though palladium can be reduced under such constant temperature conditions, the palladium is not in a state of a small particle size but in a state of an aggregate precipitate having a large particle size. With the palladium-copper catalyst finally obtained by the precipitation, palladium cannot be effectively and dispersedly coated in the porous carbon material carrier, which is not beneficial to the release of the catalytic activity of the palladium-copper catalyst.
Characterization of Palladium copper catalyst-XRD analysis, SEM analysis, XPS analysis
The palladium nanoparticles, the palladium-modified copper-based metal organic framework, and the palladium-copper catalyst prepared in example two were analyzed by XRD, respectively, and the results are shown in fig. 1 to 3.
As can be seen from fig. 1, the metallic palladium nanoparticles were generated by the low-temperature self-reduction of palladium acetate. As can be seen from fig. 2 and 3, the copper-based metal organic framework modified by palladium has high crystallinity, and a characteristic diffraction peak of metal copper appears in the palladium-copper catalyst, but a characteristic diffraction peak of metal palladium is not found, which is mainly because the supported amount of palladium nanoparticles is small and the palladium nanoparticles are highly dispersed in the porous carbon material carrier.
The results of XPS analysis of the dipalladium copper catalyst of the examples are shown in fig. 4 and 5. As can be seen from fig. 4 and 5, in the palladium-copper catalyst, the palladium component and the copper component are mainly palladium and copper in a metallic state, further indicating that the preparation method of the embodiment of the present application can indeed obtain the palladium-copper catalyst, and the palladium therein exists in a zero-valent metallic state. As for the palladium and copper in the oxidation state of small amount in fig. 4 and 5, it is a common knowledge of those skilled in the art that partial oxidation occurs due to the inevitable contact with air when the characterization of the palladium-copper catalyst is performed by XPS.
The results of analyzing the palladium-modified copper-based metal organic framework and the palladium-copper catalyst prepared by the second preparation method by SEM are shown in fig. 6 and 7. As can be seen from fig. 6, the surface of the palladium-modified copper-based metal organic framework is smoother and exhibits an octahedral structure, which indicates that the modification of the palladium nanoparticles does not affect the formation of the copper-based metal organic framework. As can be seen from fig. 7, the octahedral structure is also retained to some extent by the palladium-copper catalyst formed after calcination.
In order to test the catalytic performance of the palladium-copper catalyst, a series of application examples and performance tests of the palladium-copper catalyst are provided.
Application example one
The application example provides a method for preparing furfuryl alcohol by furfural hydrogenation, which comprises the following steps: 0.02g of the palladium-copper catalyst of the first embodiment, 5mmol of furfural and 10mL of isopropanol are placed in a 50mL high-pressure reaction kettle, the hydrogen pressure is 2MPa, the reaction temperature is 180 ℃, and the reaction time is 6 hours. The conversion rate of furfural is 83.9 percent, and the selectivity of furfuryl alcohol is 99.7 percent.
Application example two
The application example provides a method for preparing furfuryl alcohol by furfural hydrogenation, and the difference between the application example and the application example I is only that: the catalyst prepared in example two was used in this application example, the furfural conversion was 98.4%, and the furfuryl alcohol selectivity was 99.2%.
Application example three
The application example provides a method for preparing furfuryl alcohol by furfural hydrogenation, and the difference between the application example and the application example I is only that: the catalyst prepared in the third example is used in the application example, the conversion rate of the furfural is 100%, and the selectivity of the furfuryl alcohol is 98.3%.
Application example four
The application example provides a method for preparing furfuryl alcohol by furfural hydrogenation, and the difference between the application example and the application example I is only that: the catalyst prepared in the fourth example was used in this application, with a furfural conversion of 91.5% and a furfuryl alcohol selectivity of 99.5%.
Application example five
The application example provides a method for preparing furfuryl alcohol by furfural hydrogenation, and the difference between the application example and the application example I is only that: the catalyst prepared in the fifth example was used in this application, with a furfural conversion of 96.7% and a furfuryl alcohol selectivity of 99.8%.
Application example six
The application example provides a method for preparing furfuryl alcohol by furfural hydrogenation, and the difference between the application example and the application example I is only that: the catalyst prepared in the sixth example is used in the application example, the conversion rate of the furfural is 100%, and the selectivity of the furfuryl alcohol is 97.4%.
Comparative application example 1
The comparative application example provides a method for preparing furfuryl alcohol by furfural hydrogenation, and the difference between the comparative application example and the application example II is only that: the catalyst prepared in the first comparative example is used in the comparative application example, the furfural conversion rate is 48.5%, and the furfuryl alcohol selectivity is 87.9%.
Comparative application example two
The comparative application example provides a method for preparing furfuryl alcohol by furfural hydrogenation, and the difference between the comparative application example and the application example II is only that: the catalyst prepared in the comparative example is used in the comparative application example, the furfural conversion rate is 81.5%, and the furfuryl alcohol selectivity is 85.7%.
And (4) conclusion:
(1) comparing the application examples one to three with the application example one, it can be known that the addition of palladium has an important influence on the improvement of the catalytic activity of the copper catalyst, in other words, the catalytic activity of the palladium-copper catalyst in the embodiment of the present application is far greater than that of the pure copper catalyst. When the proportion of palladium nanoparticles in the palladium-copper catalyst is more, the furfural conversion rate of the palladium-copper catalyst is higher, for example, when the palladium acetate amount of example III is adopted, the furfural conversion rate of the final palladium-copper catalyst can reach 100%. However, palladium is a noble metal and has a high cost, so that experimental tests show that the palladium acetate dosage in example two can be found, and the palladium acetate dosage can combine higher furfural conversion rate and furfuryl alcohol selectivity, so that the palladium acetate is a better choice.
(2) Compared with the second application example and the fourth application example, the lower constant temperature condition and the longer constant temperature time are more beneficial to the formation of nanoparticles, and the more beneficial to the final improvement of the catalytic performance of the palladium-copper catalyst. Obviously, compared with the self-reduction condition of keeping the temperature at 20 ℃ for 24 hours, the self-reduction of palladium acetate is carried out at the temperature of 0 ℃ for 48 hours, and the furfural conversion rate of the final palladium-copper catalyst is about 7 percent higher. For the palladium-copper catalyst with the furfural conversion rate of over 90 percent, the improvement of the furfural conversion rate of 7 percent has important economic significance for the actual industrial production.
(3) Comparing the second and fifth application examples, it can be seen that the solvothermal reaction conditions also have a certain effect on the catalytic activity of the final palladium-copper catalyst, but the effect is slightly less than the effect of the palladium nanoparticle preparation step.
(4) By comparing the second application example with the sixth application example, the furfural conversion rate of the finally obtained palladium-copper catalyst reaches 100% when the roasting temperature is 500 ℃, and it can be seen that 500 ℃ is a better roasting temperature.
(5) As can be seen from the comparison of the second application example and the second comparative application example, the impregnation method can also support palladium on the copper-based metal organic framework and provide a good catalytic effect. However, when the supported amount of palladium is the same, it is obvious that the catalytic activity of the palladium-copper catalyst in the examples of the present application is much higher, the furfural conversion rate is about 17% higher, and the furfuryl alcohol selectivity is about 14% higher. The inventor finds that in the palladium-copper catalyst prepared by adopting the impregnation method, the palladium component is mainly loaded on the surface of the copper-based metal organic framework in the preparation process of the catalyst, so that the palladium component and the copper component are less in contact during roasting, the interaction between the palladium component and the copper component is weaker, and the palladium particles are easy to agglomerate and grow up during high-temperature roasting. In the preparation process of the palladium-copper catalyst, the palladium nano particles generated by self-reduction are wrapped in the copper-based metal organic framework, so that more palladium and copper component contact machines are required during roasting, a palladium-copper structure is easier to form, and meanwhile, the wrapped palladium nano particles have good high-temperature thermal stability, so that the catalytic performance is remarkably enhanced.
Cycling stability testing of palladium copper catalysts
The present application also examined the cycle stability of the palladium-copper catalyst of the above examples when carrying out furfural hydrogenation catalysis. Specifically, the catalytic experiment of application example two was carried out five times in cycles using the dipalladium-copper catalyst of example, and the results are shown in fig. 8. It should be noted that, in fig. 8, the percentages on the ordinate indicate the percentage values of the furfural conversion and the furfuryl alcohol selectivity. In the data of each circulation, the conversion rate represented by the left column bar is the furfural conversion rate, and the selectivity represented by the right column bar is the furfuryl alcohol selectivity.
And (4) conclusion: after 5 times of recycling, the palladium-copper catalyst in the embodiment of the application can still keep higher furfural conversion rate and furfuryl alcohol selectivity, wherein the furfuryl alcohol selectivity is almost unchanged, the loss of the furfuryl alcohol conversion rate is little, and the palladium-copper catalyst has good reusability and good stability. This is mainly because in the palladium copper catalyst of the present application, the palladium nanoparticles having more active catalytic performance exist in a state of being coated in the porous carbon material carrier. Thus, even if the palladium-copper catalyst after the catalytic reaction is centrifugally recovered and reused, the palladium nanoparticles are not largely lost due to the recovery process such as centrifugal separation, and are more retained on the porous carbon material carrier. Therefore, the palladium-copper catalyst can still maintain high catalytic activity after multiple cycles. The characteristic of stable structure ensures good circulation stability of the palladium-copper catalyst, and has important practical significance for industrial application.
The palladium-copper catalyst disclosed in the present application, the preparation method and the application thereof are described in detail above, and the principle and the embodiment of the present application are explained herein by using specific examples, and the description of the above examples is only used to help understanding the method and the core concept thereof; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (10)
1. A preparation method of a palladium-copper catalyst is characterized by comprising the following steps:
preparing palladium nanoparticles: dissolving palladium acetate in absolute ethyl alcohol, and treating at a constant temperature of 0-20 ℃ for 24-48 hours to obtain an absolute ethyl alcohol solution containing palladium nanoparticles;
preparing a palladium-modified copper-based metal organic framework: dissolving trimesic acid in the absolute ethanol solution containing the palladium nanoparticles, adding a copper nitrate aqueous solution, uniformly mixing, and carrying out a solvothermal reaction to obtain a palladium-modified copper-based metal organic framework;
roasting: and roasting the palladium-modified copper-based metal organic framework in an inert gas atmosphere to obtain the palladium-copper catalyst taking porous carbon as a carrier.
2. The preparation method according to claim 1, wherein in the step of preparing the palladium nanoparticles, the isothermal treatment conditions are as follows: the mixture is processed for 30 to 48 hours at a constant temperature of 0 to 10 ℃.
3. The method according to claim 1, wherein the step of preparing the palladium nanoparticles comprises: the palladium acetate was added to the absolute ethanol, and subjected to ultrasonic treatment at 0 ℃ for 10 minutes and further to constant temperature treatment at 0 ℃ for 48 hours.
4. The method according to claim 1, wherein in the step of preparing the palladium-modified copper-based metal organic framework, the conditions of the solvothermal reaction are as follows: heating from room temperature to 80-100 ℃ at a heating rate of 0.15-0.3 ℃/min, keeping the temperature for 10-15 hours at the temperature of 80-100 ℃, heating to 110-130 ℃ at a heating rate of 0.15-0.3 ℃/min, and keeping the temperature for 24-48 hours at the temperature of 110-130 ℃.
5. The method according to claim 4, wherein in the step of preparing the palladium-modified copper-based metal organic framework, the conditions of the solvothermal reaction are as follows: the temperature is raised from room temperature to 80 ℃ at the heating rate of 0.2 ℃/minute, the temperature is kept constant at the temperature of 80 ℃ for 12 hours, then the temperature is raised to 110 ℃ at the heating rate of 0.2 ℃/minute, and the temperature is kept constant at the temperature of 110 ℃ for 24 hours.
6. The production method according to any one of claims 1 to 5, wherein in the production method, the aqueous copper nitrate solution is obtained by dissolving copper nitrate trihydrate in water, the molar ratio of the palladium acetate to the copper nitrate trihydrate is 0.5:100 to 1.5:100, and the molar ratio of the copper nitrate trihydrate to the trimesic acid is 1:1 to 2: 1; the volume ratio of the absolute ethyl alcohol to the water in the copper nitrate aqueous solution is 1: 0.8-1: 1.5; in the copper nitrate aqueous solution, the dosage ratio of the copper nitrate trihydrate to the water is 1mmol:10 mL-2 mmol:10 mL.
7. The method according to any one of claims 1 to 5, wherein the firing step is: and heating the palladium-modified copper-based metal organic frame to 400-500 ℃ at a speed of 2-3 ℃/min, and roasting at a constant temperature of 400-500 ℃ for 2-3 hours to obtain the palladium-copper catalyst.
8. A palladium-copper catalyst, which is produced by the production method according to any one of claims 1 to 7.
9. The palladium-copper catalyst according to claim 8, wherein the palladium-copper catalyst comprises a porous carbon material carrier, copper nanoparticles coated inside the porous carbon material carrier, and palladium nanoparticles coated inside the porous carbon material carrier.
10. Use of a palladium-copper catalyst according to claim 8 or 9 for the catalytic hydrogenation of furfural to furfuryl alcohol.
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