CN108620064B

CN108620064B - High-specific-surface-area noble metal-based aluminosilicate catalyst and preparation method thereof

Info

Publication number: CN108620064B
Application number: CN201810336321.7A
Authority: CN
Inventors: 陈丽华; 刘宏海; 赵红娟; 汪建南; 王久江; 苏宝连; 胡清勋; 武兆东; 王宝杰; 滕秋霞; 孙雪芹; 杨周侠; 张莉; 熊晓云
Original assignee: Petrochina Co Ltd; Wuhan University of Technology WUT
Current assignee: Petrochina Co Ltd; Wuhan University of Technology WUT
Priority date: 2018-04-16
Filing date: 2018-04-16
Publication date: 2020-07-10
Anticipated expiration: 2038-04-16
Also published as: CN108620064A

Abstract

The invention provides a high specific surface area noble metal based aluminosilicate catalyst and a preparation method thereof, the preparation method comprises (1) mixing organic aluminum alkoxide and acetonitrile aqueous solution uniformly, reacting to obtain liquid; (2) uniformly mixing a silicon source and the liquid obtained in the step (1), and reacting to obtain a white precipitate I; (3) filtering, washing and drying the white precipitate I to obtain white powder II; (4) uniformly mixing the white powder II with a noble metal salt solution, standing for carrying out impregnation reaction, and drying the obtained product after the reaction is finished to obtain yellow powder III; (5) and (4) roasting the yellow powder III obtained in the step (4) under a protective atmosphere to obtain the noble metal-based aluminosilicate catalyst with high specific surface area. The catalyst prepared by the invention has a three-dimensional mesoporous structure, the mesoporous structure provides a very high specific surface area for the whole catalyst, and the active component can be uniformly distributed on the surface of the carrier when the noble metal active component is loaded.

Description

High-specific-surface-area noble metal-based aluminosilicate catalyst and preparation method thereof

Technical Field

The invention relates to a noble metal-based aluminosilicate catalyst with high specific surface area and a preparation method thereof, belonging to the technical field of petrochemical industry.

Background

In the fields of modern petrochemical industry and fine chemical industry, a catalyst with excellent performance cannot be separated. About 90% of the chemical products provided by the modern chemical industry are produced by means of catalytic processes, and catalysts are the core of catalytic technology and are of great importance to the development of catalytic processes.

As is known, a supported catalyst occupies an irreplaceable important position in the field of modern petrochemical industry, and an aluminosilicate carrier is often the most widely used catalyst or catalyst carrier in the petrochemical industry and the catalytic industry due to the advantages of good stability, low price, good surface acidity and thermal stability and the like. The noble metal nanoparticles are often used as active components to be widely applied to various catalytic reactions due to the stable chemical properties, difficult oxidation, excellent physical properties and unique catalytic activity of the noble metal nanoparticles. With the development of petrochemical industry, the components of petroleum raw materials are more and more complex, and the requirement of the industry on petroleum catalytic reaction is higher and higher. With the improvement of national requirement standards, a single conventional carrier cannot meet the requirement of a catalyst with high performance. Therefore, a new synthesis method is developed to synthesize a new decoupled catalyst carrier, and the catalyst carrier is compounded with the noble metal active component to prepare the noble metal and the catalyst with excellent pore channel properties, which is one of the trends of catalyst carrier development.

At present, the preparation method of the precious metal based aluminosilicate catalyst carrier mainly comprises the following steps: sol-gel method, precipitation method, hydrothermal synthesis method, mixing method, and the like. The methods are complex in preparation process, the parameter debugging difficulty in the synthesis process is high, and the prepared composite carrier material is accompanied by a plurality of problems. For example: the silicon-aluminum material prepared by a precipitation method or a sol-gel method often adsorbs a plurality of impurities or forms coating of the impurities in the synthesis process because of strong surface adsorbability, so that poisoning of active sites and the like are caused, and the problems also bring a series of difficulties for the subsequent compounding of noble metal active components.

Therefore, it has been desired by scientists to prepare a high specific surface area noble metal-based aluminosilicate catalyst which has high specific surface area, excellent pore channel property, adjustable pore channel property parameters and uniform distribution of noble metal active components. Wanquanzi et al synthesized an aluminosilicate mesoporous material (CN102887526A), which is a disk-shaped aluminosilicate mesoporous material with an annular pore channel structure, and the mesoporous material is obtained by a hydrothermal synthesis method in the presence of inorganic alkali by adopting a gemini cationic surfactant as a structure directing agent. The disk-shaped aluminosilicate mesoporous material with the annular pore structure has wide application prospect in the fields of catalysis, adsorption and separation, drug slow release, electronic sensing, templates for synthesizing other materials and the like. Although the material has good pore channel properties, the method is too complex to prepare on a large scale.

Therefore, providing a noble metal-based aluminosilicate catalyst with high specific surface area and a preparation method thereof has become a technical problem to be solved in the field.

Disclosure of Invention

In order to solve the above-mentioned disadvantages and drawbacks, it is an object of the present invention to provide a high specific surface area noble metal-based aluminosilicate catalyst.

The invention also aims to provide a preparation method of the high-specific surface area noble metal-based aluminosilicate catalyst.

In order to achieve the above object, the present invention provides a method for preparing a noble metal-based aluminosilicate catalyst having a high specific surface area, comprising the steps of:

(1) uniformly mixing organic aluminum alkoxide and acetonitrile aqueous solution, and reacting to obtain liquid;

(2) uniformly mixing a silicon source and the liquid obtained in the step (1), and reacting to obtain a white precipitate I (solid-liquid mixed state);

(3) filtering, washing and drying the white precipitate I obtained in the step (2) to obtain white powder II;

(4) uniformly mixing the white powder II obtained in the step (3) with a noble metal salt solution, standing for carrying out a dipping reaction, and drying the obtained product after the reaction is finished to obtain yellow powder III;

(5) and (3) roasting the yellow powder III obtained in the step (4) under a protective atmosphere to obtain the high-specific-surface-area noble metal-based aluminosilicate catalyst.

In the above preparation method, the mixing in step (1), step (2) and step (4) can be achieved by stirring, and the present invention does not require any specific stirring time, and those skilled in the art can reasonably set according to the operation requirement as long as the purpose of uniform mixing can be achieved, for example, in the specific embodiment of the present invention, the stirring time in step (4) is 1-12 hours, and further 2-6 hours.

In the above production method, preferably, the volume ratio of water to acetonitrile in the aqueous acetonitrile solution is 0.1:20 to 5: 20.

In the above preparation method, preferably, the organic aluminum alkoxide comprises one or a combination of several of n-aluminum butoxide, sec-aluminum butoxide and tert-aluminum butoxide.

In the above production method, preferably, the volume ratio of the aluminum organoxide to the acetonitrile aqueous solution is 1:5 to 1: 20. The acetonitrile used for preparing the acetonitrile aqueous solution is conventional commercially available acetonitrile, and in the specific embodiment of the invention, the acetonitrile has a mass concentration of at least 99.5%.

In the above preparation method, preferably, the step (1) of mixing the aluminum organoalkoxide with the aqueous acetonitrile solution uniformly and reacting to obtain a liquid comprises:

and dropwise adding organic aluminum alkoxide into the acetonitrile water solution, stirring for 30min to 2h, uniformly mixing, and reacting at room temperature to 60 ℃ for 5min to 24h to obtain liquid.

In the above preparation method, preferably, the step (2) of uniformly mixing the silicon source and the liquid obtained in the step (1) to react to obtain a white precipitate I, includes:

and (2) dropwise adding a silicon source into the liquid obtained in the step (1) under the stirring condition, uniformly mixing, and reacting at room temperature to 60 ℃ for 5min to 24h to obtain a white precipitate I.

In the above preparation method, preferably, the silicon source includes one or a combination of several of tetramethoxysilane, tetraethoxysilane and silica sol.

In the above preparation method, preferably, the mass ratio of the aluminum organoalkoxide to the silicon source is 20:1 to 5: 1.

In the above production method, preferably, the concentration of the noble metal salt solution is 0.001 to 0.1 mol/L.

In the above production method, preferably, the mass ratio of the noble metal element in the noble metal salt solution to the white powder II obtained in the step (3) is 1 (20-1000).

In the above preparation method, preferably, the noble metal salt includes one or a combination of hydrochloride, nitrate or sulfate of Pt, Pd, Ag, Au, Ru, Rh, Re or Ir.

In the above production method, the temperature of the drying in the step (3) is 30 to 100 ℃.

In the above preparation method, preferably, the standing time in the step (4) is 12 to 48 hours, and the standing temperature is 20 to 60 ℃.

In the above preparation method, preferably, the standing time in the step (4) is 24 to 48 hours, and the standing temperature is 20 to 40 ℃.

In the above production method, preferably, the protective atmosphere includes one of a hydrogen atmosphere, a helium atmosphere, or a nitrogen atmosphere.

In the preparation method, the roasting temperature is preferably 300-.

The invention also provides the high-specific surface area precious metal based aluminosilicate catalyst prepared by the preparation method of the high-specific surface area precious metal based aluminosilicate catalyst, the precious metal active components of the catalyst are uniformly distributed on the surface of the aluminosilicate carrier, and the catalyst has a three-dimensional mesoporous structure, wherein mesoporous channels are formed by stacking aluminosilicate nanorods, pore walls are formed by assembling mesoporous aluminosilicate nanorods, and are in filiform appearance, and the pores are communicated with one another.

In the above catalyst, preferably, the diameter of the mesoporous channel is 50-100nm, and the specific surface area of the catalyst is 300-500m²Per g, average pore diameter of 3-10nm, total pore volume of 0.3-1cm³/g。

The invention also provides application of the high-specific surface area noble metal-based aluminosilicate catalyst in deoxygenation hydrogenation reaction or catalytic oxidation reaction of biomass oil products and byproducts thereof.

According to the invention, a silicon-aluminum carrier material with through holes is synthesized in an acetonitrile aqueous solution system, and is used as a carrier, the high-specific-surface-area noble metal-based aluminosilicate catalyst is prepared by adopting an impregnation method, the prepared catalyst has a three-dimensional mesoporous structure, the mesoporous structure provides extremely high specific surface area for the whole catalyst, and the active component can be ensured to be uniformly distributed on the surface of the carrier when the noble metal active component is loaded.

In addition, the invention realizes the construction of a porous structure in the precious metal-based aluminosilicate catalyst, improves the flow diffusion performance of the material, and effectively prevents the phenomena of catalyst blockage and poisoning in the reaction process;

the noble metal-based aluminosilicate catalyst synthesized by the method has uniform pore channel distribution, greatly increases the specific surface area of the material, enables active substances to be uniformly and effectively dispersed in a carrier material, and improves the catalytic performance; the experimental synthesis condition of the catalyst is mild, the operation process is simple, the catalyst is convenient to repeat, and a large amount of the catalyst can be synthesized;

finally, in the precious metal-based aluminosilicate catalyst synthesized by the method, the pore channel structure (high specific surface three-dimensional mesopores) in the framework can effectively increase the permeability of the target catalyst, prevent dust and inorganic salt from blocking the pore channels, prolong the service life, and greatly increase the specific surface area of the material, so that the loaded precious metal active component can be more uniformly distributed on the surface of the carrier, the agglomeration of metal nano particles is reduced to a certain extent, and the catalytic activity of the catalyst is increased.

Drawings

FIG. 1 is an X-ray diffraction chart of a high specific surface area noble metal-based aluminosilicate catalyst and a solid product III obtained in example 1 of the present invention;

FIG. 2 is a scanning electron micrograph (1.00. mu.m) of a high specific surface area noble metal-based aluminosilicate catalyst prepared in example 1 of the present invention;

FIG. 3 is a scanning electron micrograph (300nm) of a high specific surface area noble metal-based aluminosilicate catalyst prepared in example 1 of the present invention;

FIG. 4 is a graph showing N of a high specific surface area noble metal-based aluminosilicate catalyst prepared in example 1 of the present invention₂Adsorption and desorption curves;

FIG. 5 is a pore size distribution curve of a high specific surface area noble metal-based aluminosilicate catalyst prepared in example 1 of the present invention;

FIG. 6 is a transmission electron microscope photograph of a high specific surface area noble metal-based aluminosilicate catalyst prepared in example 1 of the present invention.

Detailed Description

In order to clearly understand the technical features, objects and advantages of the present invention, the following detailed description of the technical solutions of the present invention will be made with reference to the following specific examples, which should not be construed as limiting the implementable scope of the present invention.

Example 1

The embodiment provides a preparation method of a high-specific-surface-area precious metal-based aluminosilicate catalyst, which comprises the following steps:

taking 17m of acetonitrile solution with the mass fraction of L being 99.5%, adding 3m of deionized water L, and uniformly mixing for later use.

Uniformly dripping 2g of aluminum sec-butoxide solution (97 wt%) into acetonitrile aqueous solution to immediately generate white precipitate, uniformly stirring for 30min, standing for 2h, dripping 0.2g of tetramethoxysilane with the mass fraction of 98% into the solution at a uniform speed, uniformly stirring for 30min by a glass rod, standing for 2min, carrying out suction filtration on the product, drying the product obtained by suction filtration in a 60 ℃ oven, and standing for 12h to obtain white powder.

Will be 1g H₂PtCl₆·6H₂O powder dissolved in 250m L H₂O, uniformly stirring, and soaking 1.5g of supported precursor in 10m L H₂PtCl₆(the loading amount is 1.0 wt%) solution, stirring for 2h, standing for 24h to obtain a solid product III, then placing the solid product III in a drying oven at 100 ℃ for drying for 12h, placing the dried sample in a tubular furnace, and roasting at the high temperature of 550 ℃ for 4h under the nitrogen protection atmosphere to obtain the noble metal-based aluminosilicate catalyst with high specific surface area, which is marked as catalyst A.

FIG. 1 is an X-ray diffraction diagram of the products obtained in this example (catalyst A and solid product III), and it can be seen from FIG. 1 that the sample shows an amorphous phase of silica-alumina.

Fig. 2 and 3 are scanning electron micrographs of the product prepared in this example, and it can be seen from fig. 2-3 that the material exhibits a three-dimensional mesoporous pore structure, and the mesopores are formed by stacking aluminosilicate nanorods.

Fig. 4 is a nitrogen adsorption and desorption isotherm graph of the product prepared in this example, and it can be seen from fig. 4 that the existence of the hysteresis loop can prove that a large number of mesopores exist in the material.

Fig. 5 is a pore size distribution diagram of the product in this example, and it can be seen from fig. 5 that the material prepared in this example has very uniform mesopores, and the average pore size is 3.32 nm. The total specific surface area of the sample was 460.75g/cm³The total pore volume is 0.40g/cm³。

Fig. 6 is a transmission electron microscope image of a catalyst sample prepared in this example, and it can be seen from fig. 6 that the noble metal active component is uniformly distributed on the surface of the support material.

Example 2

Uniformly dripping 2g of aluminum sec-butoxide solution (97 wt%) into acetonitrile aqueous solution to immediately generate white precipitate, uniformly stirring for 30min, standing for 2h, dripping 0.3g of tetramethoxysilane with the mass fraction of 98% into the solution at a uniform speed, uniformly stirring for 30min by using a glass rod, standing for 2min, carrying out suction filtration on the product, drying the product obtained by suction filtration in a 60 ℃ oven, and standing for 12h to obtain white powder.

Will be 1g H₂PtCl₆·6H₂O powder dissolved in 250m L H₂O, uniformly stirring, and soaking 1.5g of supported precursor in 5m L H₂PtCl₆(the loading amount is 0.5 wt%) solution, stirring for 2h, standing for 24h to obtain a solid product III, then placing the solid product III in a drying oven at 100 ℃ for drying for 12h, placing the dried sample in a tubular furnace, and roasting at the high temperature of 550 ℃ for 4h under the protection atmosphere of nitrogen to obtain the noble metal-based aluminosilicate catalyst with high specific surface area.

Example 3

Uniformly dripping 2g of aluminum tert-butoxide (97 wt%) into acetonitrile aqueous solution to immediately generate white precipitate, uniformly stirring for 30min, standing for 2h, dripping 0.1g of tetramethoxysilane with the mass fraction of 98% into the mixture at a uniform speed, uniformly stirring for 30min by using a glass rod, standing for 2min, carrying out suction filtration on the product, drying the product obtained by suction filtration in a 60 ℃ oven, and standing for 12h to obtain white powder.

Will be 1g H₂PtCl₆·6H₂O powder dissolved in 250m L H₂And in O, stirring uniformly. 1.5g of the supported precursor was immersed in 10ml of H₂PtCl₆(the loading amount is 1.0 wt%) solution, stirring for 2h, standing for 24h to obtain a solid product III, then placing the solid product III in a drying oven at 100 ℃ for drying for 12h, placing the dried sample in a tubular furnace, and roasting at the high temperature of 550 ℃ for 4h under the protection atmosphere of nitrogen to obtain the noble metal-based aluminosilicate catalyst with high specific surface area.

Claims

1. A preparation method of a high-specific surface area noble metal-based aluminosilicate catalyst comprises the following steps:

(1) uniformly mixing organic aluminum alkoxide and acetonitrile aqueous solution, and reacting to obtain liquid; uniformly mixing organic aluminum alkoxide and acetonitrile aqueous solution in the step (1), and reacting to obtain liquid, wherein the liquid comprises:

dropwise adding organic aluminum alkoxide into an acetonitrile water solution, stirring for 30min to 2h, uniformly mixing, and reacting at room temperature to 60 ℃ for 5min to 24h to obtain liquid; the volume ratio of the organic aluminum alkoxide to the acetonitrile aqueous solution is 1:5 to 1: 20;

(2) uniformly mixing a silicon source and the liquid obtained in the step (1), and reacting to obtain a white precipitate I; uniformly mixing a silicon source and the liquid obtained in the step (1) and reacting to obtain a white precipitate I, wherein the reaction comprises the following steps:

under the condition of stirring, dropwise adding a silicon source into the liquid obtained in the step (1), uniformly mixing, and reacting at room temperature to 60 ℃ for 5min to 24h to obtain a white precipitate I;

2. The method according to claim 1, wherein the volume ratio of water to acetonitrile in the aqueous acetonitrile solution is 0.1:20 to 5: 20.

3. The preparation method according to claim 1, wherein the organic aluminum alkoxide comprises one or more of aluminum n-butoxide, aluminum sec-butoxide and aluminum tert-butoxide.

4. The method of claim 1, wherein the silicon source comprises one or more of tetramethoxysilane, ethyl orthosilicate and silica sol.

5. The method according to claim 1 or 4, wherein the mass ratio of the aluminum organoalkoxide to the silicon source is 20:1 to 5: 1.

6. The production method according to claim 1, wherein the concentration of the noble metal salt solution is 0.001 to 0.1 mol/L.

7. The production method according to claim 1 or 6, wherein the mass ratio of the noble metal element in the noble metal salt solution to the white powder II obtained in step (3) is 1 (20-1000).

8. The method according to claim 7, wherein the noble metal salt comprises a hydrochloride, nitrate or sulfate of Pt, Pd, Ag, Au, Ru, Rh, Re or Ir.

9. The method according to claim 1, wherein the standing time in the step (4) is 12 to 48 hours and the standing temperature is 20 to 60 ℃.

10. The method according to claim 9, wherein the standing time in the step (4) is 24 to 48 hours and the standing temperature is 20 to 40 ℃.

11. The method of claim 1, wherein the protective atmosphere comprises one of a hydrogen atmosphere, a helium atmosphere, or a nitrogen atmosphere.

12. The method as claimed in claim 1 or 11, wherein the calcination temperature is 300-800 ℃ and the calcination time is 1-5 h.

13. The high specific surface area precious metal based aluminosilicate catalyst prepared by the preparation method of the high specific surface area precious metal based aluminosilicate catalyst of any one of claims 1 to 12, wherein the precious metal active component of the catalyst is uniformly distributed on the surface of the aluminosilicate carrier, and the catalyst has a three-dimensional mesoporous structure, wherein mesoporous channels are formed by stacking aluminosilicate nanorods, pore walls are formed by assembling mesoporous aluminosilicate nanorods, and have a filiform shape, and pores are communicated with one another.

14. The catalyst as claimed in claim 13, wherein the diameter of the mesoporous channel is 50-100nm, and the specific surface area of the catalyst is 300-500m²Per g, average pore diameter of 3-10nm, total pore volume of 0.3-1cm³/g。

15. The use of the high specific surface area noble metal-based aluminosilicate catalyst of claim 13 or 14 in deoxygenation hydrogenation reaction or catalytic oxidation reaction of biomass oil and its by-products.