CN113171772A - Preparation method of noble metal-based catalyst - Google Patents

Preparation method of noble metal-based catalyst Download PDF

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Publication number
CN113171772A
CN113171772A CN202110532799.9A CN202110532799A CN113171772A CN 113171772 A CN113171772 A CN 113171772A CN 202110532799 A CN202110532799 A CN 202110532799A CN 113171772 A CN113171772 A CN 113171772A
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ruthenium
solution
catalyst
noble metal
carbon
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刘国辉
王少熙
蔚志红
巩春龙
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Changchun Gold Research Institute Yantai Precious Metal Materials Research Institute Co ltd
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Changchun Gold Research Institute Yantai Precious Metal Materials Research Institute Co ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46Ruthenium, rhodium, osmium or iridium
    • B01J23/462Ruthenium
    • B01J35/40
    • B01J35/50
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/132Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
    • C07C29/136Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
    • C07C29/14Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of a —CHO group
    • C07C29/141Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of a —CHO group with hydrogen or hydrogen-containing gases

Abstract

The invention relates to a preparation method of a noble metal-based catalyst, belonging to the preparation method of catalysts. Adding a ruthenium-containing compound into a carbon slurry solution with a certain pH value, then carrying out dipping adsorption, after dipping for a period of time at room temperature, adjusting the pH value of the solution to be alkaline, adding a reducing agent with a certain concentration, carrying out isometric strong stirring reduction, carrying out positive pressure filtration after reduction for a certain period of time, then carrying out certain post-treatment operation on the prepared catalyst, mainly comprising a washing process, and then obtaining the ruthenium/carbon catalyst. The invention has the advantages that the operation is simplified, the purpose of efficiently preparing the catalyst is achieved, the noble metal nano particles can be quickly generated and uniformly dispersed on the carrier, the average size of the microcrystal can reach several nanometers, and compared with the prior art, the catalyst has smaller particle size, quick nucleation, low loading capacity, high reaction activity and effectively reduced production cost.

Description

Preparation method of noble metal-based catalyst
Technical Field
The invention relates to a preparation method of a catalyst, which is particularly suitable for preparing a supported noble metal-based catalyst by taking activated carbon as a catalyst carrier, and is particularly suitable for hydrogenation of compounds containing carbonyl and aldehyde groups, particularly for preparing sorbitol by hydrogenation of glucose in the aspect of preparing sugar alcohol.
Background
The nano particles have small size and large specific surface area, so the nano particles have excellent physical and chemical properties such as acoustoelectric and optical properties which some macroscopic materials do not have. Generally, the smaller the particle size of the nanoparticle, the higher the surface activity of the nanoparticle, the higher the surface energy of the nanoparticle, and the catalytic ability of the nanoparticle will change with the change of the particle size. The metal nano-particles have very good conductive capability, so that the electron transmission speed is accelerated, and the catalytic reaction is more favorably carried out, so that the development of the catalyst loaded by the nano-metal particles has certain practical application value for improving the reaction activity.
At present, the main methods for preparing sorbitol comprise a biological fermentation method, a catalytic hydrogenation method and the like. Wherein, the biological fermentation method has the defects of long production period, large equipment investment, complex operation, need of product decolorization and the like, and the post-treatment process is complex; the catalytic hydrogenation method is currently applied to the industrial production of sorbitol on a large scale. The catalyst used in the catalytic hydrogenation method is mainly Raney nickel catalyst at present. The Raney nickel catalyst is best used in a more alkaline solution, and the glucose aqueous solution is generally weakly acidic, so the pH of the glucose solution needs to be adjusted to about 8 before the Raney nickel catalyst is used, and the storage and transportation conditions of the Raney nickel catalyst are relatively harsh.
In addition, the Raney nickel hydrogenation catalyst has higher operating temperature of about 130-145 ℃, higher operating pressure of more than 7MPa, and higher requirements on the quality and safety performance protection grade of equipment for long-term reaction under high temperature and high pressure, so that the investment in equipment manufacture is increased undoubtedly, and the later equipment maintenance cost is increased accordingly.
However, raney nickel hydrogenation catalysts have a price advantage, and are still adopted by most companies at present, so that how to develop excellent low-cost and high-performance ruthenium-based noble metal catalysts suitable for preparing sorbitol by glucose hydrogenation is of great significance.
At present, the preparation method of the noble metal-based catalyst mainly comprises the following steps:
(1) the dipping method comprises the following steps: adding a solution containing a noble metal precursor into a solution containing a carrier, stirring for a certain time, reducing by using an organic solvent or other substances with reducibility at a certain temperature, and then filtering, washing and drying to obtain the corresponding noble metal-loaded carrier catalyst.
(2) A precipitation method: adding a precursor solution containing noble metal to a solution containing carrier, adding an alkaline substance such as NaOH, KOH and NH3·H2O, etc., converting the noble metal ion into an insoluble compound such as a hydroxide, etc., attaching it to a carrier, and passing H2Reducing the reducing substance. Currently, H is mainly used in industry2As a reducing agent, the reduction temperature is generally controlled to be more than 200 ℃, the production cost of the catalyst is higher, and the requirement on operation safety is higher.
The main problems of the traditional preparation methods of the ruthenium carbon catalyst, such as an impregnation method and a precipitation method, are that the dispersity of Ru is low and the size of the formed Ru nano particles is large, so that the catalyst activity is low and the like.
Disclosure of Invention
The invention provides a preparation method of a noble metal-based catalyst, which aims to solve the problem that the ruthenium Ru in the catalyst cannot be completely loaded to cause the effective Ru component to be lower, and how to quickly and efficiently prepare the noble metal-loaded catalyst which can be stored at room temperature and be applied to high-efficiency hydrogenation, control the size of Ru nanoparticles and relieve the aggregation of the Ru nanoparticles.
The technical scheme adopted by the invention is as follows: comprises the following steps:
(1) weighing 200-300 meshes, and the specific surface area is 1000-2000 m2Adding the powder active carbon per gram into a three-neck flask or a beaker; according to the method, the pretreatment work of the activated carbon at the early stage is not required, so that the pretreatment cost and time of the catalyst carrier are saved. Adding ultrapure waterInto activated carbon, wherein the volume weight ratio of the ultrapure water to the activated carbon is V(Water):m(activated carbon)Stirring at a low speed of 1-20, adding a ruthenium-containing Ru precursor compound (determined according to the loading amount) into the carbon slurry solution, adjusting the pH value of the solution to obtain an impregnation mixed solution of the ruthenium-containing carbon solution,
(2) dipping the dipping mixed solution containing the ruthenium-carbon solution for 45 min-3 h, and then adjusting the pH value of the dipping mixed solution to 10-11 again;
(3) adding a reducing agent, wherein the molar ratio of the reducing agent to Ru atoms is 1: 1, preparing a solution with the same volume as the impregnation mixed solution, adding the solution into the step (2), and rapidly increasing the stirring speed to 450-500 rpm/min, wherein the reduction time is 1-2 h, and the reduction temperature is 10-30 ℃;
(4) after reduction, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, obtaining the ruthenium-carbon catalyst after filtration, and sealing and storing at room temperature for later use, wherein the electric conductivity is less than 20 mu s/cm.
The noble metal of the invention also comprises any one of gold Au, silver Ag, rhodium Rh, palladium Pd and platinum Pt.
The mass percentage of the noble metal is 0.5-5%.
In the step (1), the precursor compound containing ruthenium Ru is chlorine-containing ruthenium salt.
The volume weight ratio of the ultrapure water to the activated carbon in the step (1) is V(Water):m(activated carbon)=2~14。
The pH value of the dipping mixed solution of the ruthenium-containing carbon solution in the step (1) is 0.8-7.
The dipping temperature of the dipping mixed solution of the ruthenium-containing carbon solution in the step (2) is 10-30 ℃.
The reducing agent in the step (3) adopts methanol, ethanol, glycol, ascorbic acid AA and potassium borohydride KBH4Or sodium borohydride.
The key point of the invention is that the pH value of the Ru solution is controlled between 10 and 11 before the reduction process, the addition amount of the reducing agent is controlled, and the Ru solution is prepared into an isometric solution and then added under high-speed stirring to prevent the newly generated Ru nano particles from growing and aggregating. The specific action mechanism is that the concentration of the reducing agent is reduced after the reducing agent is prepared into an equal volume, the contact probability of the reducing agent and ruthenium ions is reduced, and the quantity of Ru nano particles generated around the reducing agent is reduced, so that the aggregation of a large quantity of Ru nano particles is effectively prevented from growing, the generated Ru nano particles are quickly transferred at high-speed stirring frequency, the contact chance with the newly generated Ru nano particles is reduced, the growth of Ru crystal particles is slowed down, and the Ru nano particles are adsorbed by a carrier and limited in migration growth, so that the effect of stabilizing the Ru nano particles is achieved.
Ruthenium loaded on the carrier of the activated carbon exists in the form of ultra-small-size microcrystals, the average size of Ru nanoparticles is 2.9nm, and the content of the ruthenium loaded on the activated carbon carrier can be controlled between 0.5 and 5 percent according to the situation or other loads can be adjusted according to needs.
In comparison, the operating conditions of the ruthenium-based noble metal catalyst are relatively mild, the operating temperature can be reduced to 120 ℃, the operating pressure can be reduced to 4MPa, the requirements on production operating conditions are reduced, the production cost is reduced, and the safety performance is improved. In terms of catalytic performance, the activity of the ruthenium-based noble metal catalyst is also remarkably improved compared with that of a Raney nickel catalyst, and the catalyst has good catalytic activity particularly in a hydrogenation reaction for preparing sorbitol by hydrogenating glucose. In conclusion, the ruthenium-based noble metal catalyst has the advantages of high activity, good selectivity, high product quality, relatively mild operation conditions, low equipment investment, stable catalyst performance and the like.
The method adopts the control process operations such as an isometric reduction mode and the like, has the advantages of easy operation, high reproducibility, no need of pretreatment on a used carrier in the preparation process, low preparation cost, small size of the prepared Ru nano particles loaded on the catalyst, high catalytic activity, high glucose conversion rate, high selectivity and the like particularly in the process of preparing sorbitol by glucose hydrogenation, and mild operation process conditions.
The preparation of the ruthenium-based noble metal catalyst can overcome the defects of a Ni-containing catalyst, can be used under the weak acidic condition, and in the catalytic hydrogenation reaction process, the active component ruthenium loaded on the carrier has certain stability and can be stored under the room-temperature air environment condition.
The ruthenium nanoparticles of the supported noble metal catalyst of the carbon-supported ruthenium nanoparticles have high catalytic activity for hydrogenation deoxidation of carbonyl chemical bonds, particularly have important research significance for reactions for preparing sorbitol by glucose hydrogenation and the like, and have low cost, high safety and high performance for preparing the ruthenium-carbon catalyst for preparing the sorbitol by glucose hydrogenation.
Drawings
FIG. 1 is a graph showing the specific surface area of a ruthenium carbon catalyst support according to the present invention;
as can be seen from FIG. 1, the adsorption specific surface area of the carrier activated carbon adopted by the catalyst reaches 1040m2The catalyst has a large specific surface area and good adsorption activity, and is suitable for serving as a catalyst carrier;
FIG. 2 is an XRD pattern of a ruthenium carbon catalyst of the present invention;
as can be seen from the X-ray diffraction pattern analysis of FIG. 2, the catalyst is mainly composed of carbon, and has a diffraction peak of a metal ruthenium atom;
FIG. 3 is a TEM image of a pre-ruthenium carbon catalyst used in the present invention;
as can be seen from FIG. 3, the catalyst loading is relatively uniform, the agglomeration phenomenon is not obvious, the ruthenium nanoparticles are uniformly loaded on the activated carbon carrier, the particles are smaller, and the average size of the ruthenium nanoparticles is about 2.9 nm;
FIG. 4 TEM image of ruthenium carbon catalyst after 21 times use;
as can be seen from fig. 4, after the catalyst is used 21 times, the surface of the catalyst is not significantly changed, and the active component ruthenium nanoparticles in the catalyst are not grown or aggregated, indicating that the catalyst has a certain stability.
Detailed Description
The invention uses a new isometric reduction mode, the type of reducing agent and the impregnation time of the used catalyst carrier, the impregnation pH value and the preparation reduction time are different, so the embodiment is selected from the aspects.
In the following scheme, an X-ray diffractometer (XRD) and a Transmission Electron Microscope (TEM) are adopted to measure the particle size of ruthenium nanoparticles and the change condition of a catalyst before and after reaction, a hydrogenation high-pressure reaction kettle is adopted to measure the activity of the catalyst, the reaction temperature is 106 ℃, the reaction pressure is 4MPa, the dosage of the catalyst accounts for 2.5% of the mass of a glucose solution, hydrogenation liquid is recovered when the reaction is finished, and the content and the conversion rate of a reaction product are analyzed by adopting a reducing sugar titration method and a high-performance liquid chromatography.
Example 1
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material to prepare the ruthenium carbon catalyst with the loading of 1 percent.
0.2703g of RuCl were weighed out3·xH2O (Ru content is not less than 37%) and ultrapure water, V(ultrapure water):m(Carrier)Firstly, adding 10g of activated carbon carrier into a three-neck flat-bottom flask, then adding 140mL of ultrapure water, stirring for a few minutes, then adding a ruthenium-containing solution, adjusting the pH to 1, and then soaking and adsorbing at room temperature (25 ℃) for 3 hours to obtain a ruthenium-containing carbon carrier adsorption solution; after the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) reducing, namely, rapidly adding a reducing agent; in the reduction process, the stirring speed is controlled to be about 450-500 rpm/min, and the reduction time is 1 h; and in the reduction process, controlling the pH value to be 9 by using 5M NaOH, removing the impregnation liquid by adopting a positive pressure filtration mode after the reduction is finished, washing the catalyst solid powder to be neutral by adopting ultrapure water, and finally obtaining the ruthenium/carbon catalyst after filtration, and sealing and storing at room temperature for later use.
Example 2
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material to prepare the ruthenium carbon catalyst with the loading of 1 percent.
0.2703g of RuCl were weighed out3·xH2O (Ru content is not less than37%) and a suitable amount of ultrapure water (V)(ultrapure water):m(Carrier)14). First, 10g of an activated carbon support was added to a three-necked flat-bottomed flask, 140mL of ultrapure water was added thereto, and after stirring for a few minutes, a ruthenium-containing solution was added thereto, and the mixture was immersed and adsorbed at room temperature (25 ℃) for 1 hour with the pH adjusted to 1 to obtain a ruthenium-containing carbon support adsorption solution. After the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) and adding the reducing agent after preparing the solution with the same volume, wherein the stirring speed is controlled to be about 450-500 rpm/min in the adding and reducing processes, and the reducing time is 1 h. pH of the solution at the end of the reduction>9. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Example 3
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material to prepare the ruthenium carbon catalyst with the loading of 1 percent.
0.2703g of RuCl were weighed out3·xH2O (Ru content is more than or equal to 37%) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). Firstly, 10g of activated carbon carrier is added into a three-mouth flat-bottom flask, then 140mL of ultrapure water is added, after stirring for a few minutes, a ruthenium-containing solution is added, and the mixture is immersed and adsorbed at room temperature (25 ℃) for 45min by adjusting the pH to 1, so as to obtain a ruthenium-containing carbon carrier adsorption solution. After the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) and adding the reducing agent after preparing the solution with the same volume, wherein the stirring speed is controlled to be about 450-500 rpm/min in the adding and reducing processes, and the reducing time is 1 h. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Example 4
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material to prepare the ruthenium carbon catalyst with the loading of 1 percent.
0.2703g of RuCl were weighed out3·xH2O (Ru content is more than or equal to 37%) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). Firstly, 10g of activated carbon carrier is added into a three-mouth flat-bottom flask, then 140mL of ultrapure water is added, after stirring for a few minutes, a ruthenium-containing solution is added, and the mixture is immersed and adsorbed at room temperature (25 ℃) for 3 hours under the condition that the pH value is adjusted to be 1, so that a ruthenium-containing carbon carrier adsorption solution is obtained. After the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) and adding the reducing agent after preparing the solution with the same volume, wherein the stirring speed is controlled to be about 450-500 rpm/min in the adding and reducing processes, and the reducing time is 1 h. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Example 5
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material to prepare the ruthenium carbon catalyst with the loading of 1 percent.
0.2703g of RuCl were weighed out3·xH2O (Ru content is more than or equal to 37%) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). Firstly, 10g of activated carbon carrier is added into a three-mouth flat-bottom flask, then 140mL of ultrapure water is added, after stirring for a few minutes, a ruthenium-containing solution is added, and the mixture is soaked and adsorbed at room temperature (25 ℃) for 3 hours under the condition that the pH value is adjusted to be 2, so that a ruthenium-containing carbon carrier adsorption solution is obtained. After the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) the reducing agent is added quickly, and the stirring speed is high in the reduction processControlling the speed to be about 450-500 rpm/min, and the reduction time to be 1 h. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Example 6
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material, and the ruthenium carbon catalyst with the loading of 0.5 percent is prepared.
0.2703g of RuCl were weighed out3·xH2O (Ru content is more than or equal to 37%) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). Firstly, 10g of activated carbon carrier is added into a three-mouth flat-bottom flask, then 140mL of ultrapure water is added, after stirring for a few minutes, a ruthenium-containing solution is added, and the mixture is soaked and adsorbed at room temperature (25 ℃) for 3 hours under the condition that the pH value is adjusted to be 7, so that a ruthenium-containing carbon carrier adsorption solution is obtained. After the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) the reducing agent is added rapidly, the stirring speed is controlled to be about 450-500 rpm/min in the reduction process, and the reduction time is 1 h. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Example 7
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material to prepare the ruthenium carbon catalyst with the loading of 1 percent.
0.2703g of RuCl were weighed out3·xH2O (Ru content is more than or equal to 37%) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). Firstly, 10g of activated carbon carrier is added into a three-mouth flat-bottom flask, then 140mL of ultrapure water is added, after stirring for a few minutes, a ruthenium-containing solution is added, and the mixture is immersed and adsorbed at room temperature (25 ℃) for 3 hours under the condition that the pH value is adjusted to be 1, so that a ruthenium-containing carbon carrier adsorption solution is obtained. Adsorption time of impregnationAdjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) and preparing an isometric solution, adding the isometric solution, controlling the stirring speed to be about 450-500 rpm/min in the reducing process, and controlling the reducing time to be 1 h. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Comparative example 1
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is a catalyst carrier material.
36.6mM RuCl was weighed3·xH2O27.03 mL (Ru content is more than or equal to 37 percent) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). First, 10g of an activated carbon support was added to a three-necked flat-bottomed flask, 140mL of ultrapure water was added thereto, and after stirring for a few minutes, a ruthenium-containing solution was added thereto, and after adjusting the pH to 1, the mixture was adsorbed by dipping at room temperature (25 ℃) for 3 hours to obtain a ruthenium-containing carbon support adsorption solution. And (3) after the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, adding a proper amount of reducing agent Ascorbic Acid (AA) into the solution when the pH value is controlled to be 10-11 (the molar ratio of Ru atoms to AA is 1: 1), and controlling the stirring speed to be about 450-500 rpm/min in the reduction process for 1 h. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Comparative example 2
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is a catalyst carrier material.
36.6mM RuCl was weighed3·xH2O27.03 mL (Ru content is more than or equal to 37 percent) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). Firstly, 10g of active carbon carrier is added into a three-mouth flat-bottom flask, and then 14g of active carbon carrier is addedAfter stirring with 0mL of ultrapure water for a few minutes, a ruthenium-containing solution was added, and the mixture was adjusted to pH 1 and then adsorbed by immersion at room temperature (25 ℃) for 3 hours to obtain a ruthenium-containing carbon support adsorption solution. And (3) after the dipping adsorption time is up, adjusting the pH value of the dipping solution to be alkaline by using a 5M NaOH solution, adding a proper amount of reducing agent ethylene glycol (the molar ratio of Ru atoms to ethylene glycol is 1: 1) into the solution when the pH value is controlled to be between 10 and 11, and controlling the stirring speed to be about 450 to 500rpm/min and the reduction time to be 1h in the reduction process. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Comparative example 3
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material, and the ruthenium carbon catalyst with the loading of 0.5 percent is prepared.
0.1351g of RuCl were weighed out3·xH2O (Ru content is more than or equal to 37%) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). Firstly, 10g of activated carbon carrier is added into a three-mouth flat-bottom flask, then 140mL of ultrapure water is added, after stirring for a few minutes, a ruthenium-containing solution is added, and the mixture is immersed and adsorbed at room temperature (25 ℃) for 3 hours under the condition that the pH value is adjusted to be 1, so that a ruthenium-containing carbon carrier adsorption solution is obtained. After the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) and preparing an isometric solution, adding the isometric solution, controlling the stirring speed to be about 450-500 rpm/min in the reducing process, and controlling the reducing time to be 1 h. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
Comparative example 4
Weighing 10g (dry basis) of 200-300 meshes and specific surface area of 1040m2The carbon carrier is used as a catalyst carrier material to prepare the ruthenium carbon catalyst with the load of 5 percent.
1.3514g of RuCl were weighed out3·xH2O (Ru content is more than or equal to 37%) and a proper amount of ultrapure water (V)(ultrapure water):m(Carrier)14). Firstly, 10g of activated carbon carrier is added into a three-mouth flat-bottom flask, then 140mL of ultrapure water is added, after stirring for a few minutes, a ruthenium-containing solution is added, and the mixture is immersed and adsorbed at room temperature (25 ℃) for 3 hours under the condition that the pH value is adjusted to be 1, so that a ruthenium-containing carbon carrier adsorption solution is obtained. After the impregnation adsorption time is up, adjusting the pH value of the impregnation liquid to be alkaline by using a 5M NaOH solution, and adding a proper amount of reducing agent KBH into the solution when the pH value is controlled to be 10-114(Ru atom and KBH)41: 1) and preparing an isometric solution, adding the isometric solution, controlling the stirring speed to be about 450-500 rpm/min in the reducing process, and controlling the reducing time to be 1 h. And after the reduction is finished, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, wherein the electric conductivity is less than 20 mu s/cm, finally filtering to obtain the ruthenium/carbon catalyst, and sealing and storing at room temperature for later use.
The catalysts obtained in the respective examples and comparative examples were evaluated for their catalytic activity, and the results are shown in Table 1.
TABLE 1 comparison of ruthenium carbon catalyst Performance
Figure BDA0003067966280000081
Figure BDA0003067966280000091
As can be seen from Table 1, the conversion of 100% of glucose can be achieved by using the ruthenium/carbon catalyst prepared by the present invention, which is significantly higher than the ruthenium/carbon catalyst prepared by the conventional method. The use of different reducing agents can be found to have a great influence on the preparation of the catalyst and the performance thereof by comparing the comparative examples 1 and 2, and the performance of the reducing agent using potassium borohydride is better than that using ethylene glycol and ascorbic acid by comparing the reducing agents, so that the reducing agent in the patent is mainly optimized around potassium borohydride in a deep search. Since potassium borohydride has strong reducibility, the addition mode and the addition speed of the reducing agent (equal volume of rapid reduction) need to be controlled so as to prevent aggregation of the reduced ruthenium nanoparticles. It can be seen from comparative examples 3 and 4 that different loading amounts have certain influence on the catalytic activity of the catalyst, when the loading amount is lower, the catalytic activity requirement for complete conversion of glucose cannot be met, and when the loading amount is too high, the catalytic activity can reach the goal of complete conversion of glucose, but the high loading amount increases the use cost of the catalyst, so the preparation form of the catalyst needs to be comprehensively considered from factors such as economy and catalytic activity.
Compared with the prior art, the preparation method has the main advantages of low catalyst loading rate, small Ru nano particles, high reaction activity, low temperature in the preparation process, mild reaction conditions, capability of being stored at room temperature and effective reduction of cost.

Claims (8)

1. A method for preparing a noble metal-based catalyst, comprising the steps of:
(1) weighing 200-300 meshes, and the specific surface area is 1000-2000 m2Adding the powder active carbon per gram into a three-neck flask or a beaker; adding ultrapure water into activated carbon, wherein the volume weight ratio of the ultrapure water to the activated carbon is V(Water):m(activated carbon)Stirring at a low speed of 1-20, adding a ruthenium-containing Ru precursor compound into the carbon slurry solution, adjusting the pH value of the solution to obtain a dipping mixed solution of the ruthenium-containing carbon solution,
(2) dipping the dipping mixed solution containing the ruthenium-carbon solution for 45 min-3 h, and then adjusting the pH value of the dipping mixed solution to 10-11 again;
(3) adding a reducing agent, wherein the molar ratio of the reducing agent to Ru atoms is 1: 1, preparing a solution with the same volume as the impregnation mixed solution, adding the solution into the step (2), and rapidly increasing the stirring speed to 450-500 rpm/min, wherein the reduction time is 1-2 h, and the reduction temperature is 10-30 ℃;
(4) after reduction, removing the impregnation liquid by adopting a positive pressure filtration mode, then washing the catalyst solid powder to be neutral by adopting ultrapure water, obtaining the ruthenium-carbon catalyst after filtration, and sealing and storing at room temperature for later use, wherein the electric conductivity is less than 20 mu s/cm.
2. The method for producing a noble metal-based catalyst according to claim 1, wherein: the noble metal also comprises any one of gold Au, silver Ag, rhodium Rh, palladium Pd and platinum Pt.
3. The method for producing a noble metal-based catalyst according to claim 1, wherein: the mass percentage of the noble metal is 0.5-5%.
4. The method for producing a noble metal-based catalyst according to claim 1, wherein: the ruthenium Ru precursor compound in the step (1) is chlorine-containing ruthenium salt.
5. The method for producing a noble metal-based catalyst according to claim 1, wherein: the volume weight ratio of the ultrapure water to the activated carbon in the step (1) is V(Water):m(activated carbon)=2~14。
6. The method for producing a noble metal-based catalyst according to claim 1, wherein: the pH value of the dipping mixed solution of the ruthenium-containing carbon solution in the step (1) is 0.8-7.
7. The method for producing a noble metal-based catalyst according to claim 1, wherein: the dipping temperature of the dipping mixed solution of the ruthenium-containing carbon solution in the step (2) is 10-30 ℃.
8. The method for producing a noble metal-based catalyst according to claim 1, wherein: the reducing agent in the step (3) adopts methanol, ethanol, glycol, ascorbic acid AA, potassium borohydride KBH4Or sodium borohydride.
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