CN114105120A - A kind of preparation method of small size carbon ball material and its application - Google Patents

Abstract

The application discloses a preparation method of a small-size modified carbon sphere material, which comprises the following steps: carrying out hydrothermal reaction on an aqueous solution containing a carbon source and a structure regulating agent to obtain a hydrothermal carbon sphere material; wherein the structure regulating agent is at least one of polyethylene glycol, sodium polyacrylate, citric acid, stearic acid, palmitic acid and dodecylbenzene sulfonic acid. And then modifying the hydrothermal carbon sphere material to increase the number of oxygen-containing functional groups on the surface. According to the method, a proper structure regulating agent is selected, and a small-size modified carbon sphere material with the particle size of 50-200 nm is prepared by simple hydrothermal reaction and modification treatment.

Description

Preparation method and application of small-size carbon sphere material

Technical Field

The application relates to a preparation method and application of a small-size carbon sphere material, and belongs to the technical field of nano materials.

Background

The hydrothermal carbon spheres have stable chemical properties, good thermal stability, and excellent electrical conductivity and thermal stability. The small-size carbon spheres have light weight and large specific surface area, and can play greater advantages in practical application. And with the reduction of the size of the carbon spheres, the specific surface area is increased, the transmission path is shortened, and the performance is better. Toxic reagents are not used in the process of preparing the monodisperse colloid nanospheres by adopting the glucose aqueous solution, so that the prepared carbon nanospheres are non-toxic, and compared with the traditional chemical vapor deposition, high-temperature carbonization and arc discharge methods, the hydrothermal carbon nanosphere preparation method is more environment-friendly. However, in the process of hydrothermal preparation of carbon spheres from glucose, the surface energy control influences, and it is difficult to stably and uniformly maintain a small-size state in the hydrothermal process, so that the carbon spheres synthesized by the current hydrothermal method have a large size, and the diameter is generally between 300nm and 10 μm.

Sufficient experiments prove that after the hydrothermal carbon spheres are modified properly, the number of oxygen-containing functional groups on the surfaces of the hydrothermal carbon spheres can be increased, negative charges can be increased, and more metal ions can be attached. Can effectively adsorb heavy metal ions as the adsorbent, when being as template agent, can make the hollow ball shell thickness that finally forms increase, intensity increase, be favorable to the practical application of hollow ball, can also be applied to the catalysis field through the effective load noble metal of electrostatic action.

When the carbon sphere material is adopted, the modification research is less discussed. For example, Sun and Li in DOI 10.1002/anie.200352386 are synthesized into carbon spheres with the size of 150-1500 nm by a hydrothermal method for the first time, and the particle size distribution and the particle size of the carbon spheres are large. In document DOI 10.1002/anie.200353212 Ga is synthesized when carbon spheres are used as hard templates₂O₃And when the GaN hollow sphere is adopted, the influence of the modification of the carbon sphere template on the appearance of the hollow sphere is not discussed. Lai and Wang in the document DOI 10.1002/ange.201004900 and the like adopt sugar emulsion polymerization to form carbon spheres, the size of the carbon spheres reaches more than 2 mu m, the sizes are not uniform, and modification treatment is not carried out.

Therefore, how to adopt a simple hydrothermal method to controllably prepare the carbon spheres with small sizes, especially 50-200 nm, is still a technical problem, and what way to modify the carbon spheres simultaneously enables more metal ions to be attached to the surfaces of the carbon spheres, so that the application range of the carbon spheres is expanded, and the problem to be further solved is solved.

Disclosure of Invention

According to the first aspect of the application, the method for preparing the carbon sphere material is used for preparing the carbon sphere material with the particle size of 50-200 nm by selecting a proper structure regulating agent and utilizing a simple hydrothermal reaction.

A method for preparing a carbon sphere material, comprising:

carrying out hydrothermal reaction on an aqueous solution containing a carbon source and a structure regulating agent to obtain a carbon sphere material;

wherein the structure regulating agent is at least one of polyethylene glycol PEG, sodium polyacrylate, citric acid, stearic acid, palmitic acid and dodecylbenzene sulfonic acid, wherein the polyethylene glycol is preferably at least one of PEG-2000, PEG-4000, PEG-6000, PEG-8000, PEG-10000 and PEG-20000.

Optionally, the concentration of the carbon source in the aqueous solution is 0.2-1 mol/L.

Optionally, the lower limit of the concentration of the carbon source in the aqueous solution is 0.2mol/L, 0.33mol/L and 0.55mol/L, and the upper limit is selected from 0.33mol/L, 0.58mol/L and 1 mol/L.

Optionally, the mass of the structure regulator is 0.1-1% of the mass of the carbon source.

Optionally, the lower limit of the mass percentage of the structure regulator to the carbon source is selected from 0.1%, 0.19%, 0.2%, 0.67%, 0.84%, and the upper limit is selected from 0.19%, 0.2%, 0.67%, 0.84%, 1%.

Optionally, the carbon source is selected from at least one of glucose, fructose, sucrose.

Alternatively, the specific conditions of the hydrothermal reaction include:

the reaction temperature is 185-220 ℃;

the reaction time is 2-12 h.

Optionally, the reaction temperature has a lower limit selected from 185 ℃, 190 ℃, 200 ℃, 210 ℃ and an upper limit selected from 190 ℃, 200 ℃, 210 ℃, 220 ℃.

Alternatively, the lower limit of the reaction time is selected from 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h and 11h, and the upper limit is selected from 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h and 12 h.

Preferably, the filling degree of the hydrothermal reaction kettle is 60-80%.

Further, after hydrothermal reaction, centrifugal separation, washing and drying are carried out to obtain a product;

wherein the specific conditions of the centrifugal separation include:

the rotating speed is 8000-11000 r/min, and the centrifugation time is 5-15 min;

the washing comprises the following steps:

washing with water and ethanol for at least three times;

the drying comprises:

the method is carried out under the vacuum condition, and the drying temperature is 60-80 ℃.

Further, after the carbon sphere material is obtained, the method further comprises the following steps:

and placing the carbon sphere material in a modification solution for modification reaction to obtain the modified carbon sphere material.

Optionally, the modifying solution comprises liquid a and liquid B;

wherein the liquid A is selected from at least one of methanol, ethanol, acetone and dichloromethane;

optionally, liquid B is an aqueous acid or base solution;

optionally, the acid is at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid;

optionally, the base is an alkali metal hydroxide.

Optionally, the volume ratio of the liquid a to the liquid B is 1: 2-10;

optionally, the lower limit of the volume ratio of the liquid A to the liquid B is selected from 1: 2. 1: 3. 1: 4. 1: 5. 1: 6. 1: 7. 1: 8. 1: 9, upper limit selected from 1: 3. 1: 4. 1: 5. 1: 6. 1: 7. 1: 8. 1: 9. 1: 10.

preferably, the concentration of the liquid B is 1-6 mol/L, wherein the molar amount of the liquid B is calculated by the molar amount of the acid or alkali compound in the liquid B.

Alternatively, the lower limit of the concentration of the liquid B is selected from 1mol/L, 2mol/L, 3mol/L, 4mol/L and 5mol/L, and the upper limit is selected from 2mol/L, 3mol/L, 4mol/L, 5mol/L and 6 mol/L.

Alternatively, specific conditions of the modification reaction include:

the reaction temperature is 25-180 ℃, and the reaction time is 3-24 h.

Optionally, the lower limit of the reaction temperature is selected from 25 ℃, 100 ℃, 150 ℃, and the upper limit is selected from 100 ℃, 150 ℃, 180 ℃.

Optionally, the lower limit value of the reaction time is selected from 3h, 8h and 12h, and the upper limit value is selected from 8h, 12h and 24 h.

Optionally, the particle size of the carbon sphere material is 50-200 nm.

Preferably, the particle size of the carbon sphere material is 50-140 nm.

Optionally, the average particle size of the carbon sphere material is 60-150 nm.

Optionally, the average particle size of the carbon sphere material is 60-140 nm.

In a second aspect of the application, a carbon sphere material prepared by any one of the methods is also provided.

In a third aspect of the application, an application of the carbon sphere material prepared by any one of the methods described above as a template agent in preparation of a hollow sphere material containing metal ions, an application of the carbon sphere material as an adsorbent in adsorption of heavy metal ions, and an application of the carbon sphere material as a catalyst carrier for loading noble metals in the field of catalysis is also provided.

Specifically, the metal ion-containing material includes at least one of a perovskite material and a metal oxide.

The beneficial effects that this application can produce include:

(1) the carbon sphere material with the particle size of 50-200 nm can be prepared by simple hydrothermal reaction by adopting the regulating agent with a specific structure.

(2) According to the invention, the hydrothermal carbon spheres with good dispersibility and uniform size of 50-200 nm are prepared by regulating and controlling the glucose concentration, the adding amount of the structure regulating agent, the hydrothermal temperature and the hydrothermal time.

(3) Through a simple modification mode, the number of oxygen-containing functional groups on the surface of the activated carbon sphere is increased, and the negative charge on the surface is increased, so that metal ions can be better attached to the activated carbon sphere. The reason is that: the action of the metal ions on the surface of the carbon sphere is mainly based on electrostatic adsorption, and when a proper modification mode is adopted, electronegative functional groups such as hydroxyl groups on the surface of the carbon sphere are added, so that the electrostatic attraction between the carbon sphere and the metal positive ions can be enhanced, and the adsorption of the metal ions is increased.

(4) The method can realize the controllable preparation of the small-size carbon spheres, and simultaneously discusses a proper modification mode, so that the surface properties of the small-size carbon spheres are optimized, and the application range of the small-size carbon spheres is expanded.

Drawings

FIG. 1 is a scanning electron micrograph of a carbon sphere obtained in example 1 of the present invention;

FIG. 2 is a particle size distribution diagram of carbon spheres obtained in example 1 of the present invention;

FIG. 3 is a scanning electron micrograph of a carbon sphere obtained in example 2 of the present invention;

FIG. 4 is a scanning electron micrograph of a carbon sphere obtained in example 3 of the present invention;

FIG. 5 is a scanning electron micrograph of a carbon sphere obtained in example 4 of the present invention;

FIG. 6 is a scanning electron micrograph of a carbon sphere obtained in example 5 of the present invention;

FIG. 7 is a scanning electron micrograph of a carbon sphere obtained in comparative example 1 of the present invention;

FIG. 8 is a scanning electron micrograph of a carbon sphere obtained in comparative example 2 of the present invention;

fig. 9 is a fourier infrared spectrum of the carbon spheres obtained in examples 2, 3 and 4 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Wherein the sodium polyacrylate is purchased from Shanghai Michelin Biotechnology, Inc.;

polyethylene glycol was purchased from Yibaishun science and technology Limited, Shenzhen city;

citric acid was purchased from Shanghai Michelin Biotech, Inc.

The morphological characteristics of the sample are analyzed through a Scanning Electron Microscope (SEM) test, the analysis instrument is a JSM6360LV scanning electron microscope, and the performance indexes are as follows: accelerating voltage is 0.5-30 kV, and amplification factor is as follows: 18-50000 times, resolution: high vacuum of 3.0nm and low vacuum of 4.5 nm. Attached energy spectroscopy and EBSD analysis systems. And (4) counting the sample particle size distribution in the SEM image through NanoMeasure software, and obtaining a particle size distribution map through Origin software.

The surface functional groups of the sample are analyzed by Fourier infrared spectrum test, the analytical instrument is a Varian3100 type infrared spectrometer, and sampling is carried out by adopting a solid powder diffuse reflection mode, and the instrument resolution is 4cm^-1The scanning range is 4000-700cm^-1And the data accumulation is carried out by scanning 32 times.

The Zeta potential of the sample is tested and analyzed by an electrophoresis method, and an analysis instrument is a Zetasizer Nano type Nano laser particle analyzer. Taking a proper amount of sample, dissolving the sample in water, adjusting the pH value of the solution, and taking supernatant for analysis.

The specific embodiment is as follows:

example 1

(1) Dissolving 105g of glucose and 0.2g of PEG10000 in 1L of deionized water, and ultrasonically mixing uniformly for 15 min;

(2) transferring 68mL of the uniform solution to a 100mL hydrothermal kettle, sealing, placing in a 190 ℃ oven for hydrothermal treatment for 4 hours, and naturally cooling to room temperature after the reaction is finished;

(3) taking out the product in the hydrothermal kettle, centrifuging for 8min at 11000r/min, washing for three times by using deionized water and ethanol respectively, and drying in a vacuum oven at 60 ℃;

(4) and (4) carrying out no treatment on the product obtained in the step (3).

Fig. 1 is a scanning electron microscope image of the carbon spheres obtained in example 1, and it can be seen from the image that the carbon spheres have uniform size, high sphericity and good dispersibility. As can be seen from the particle size distribution diagram of FIG. 2, the average particle size of the carbon spheres is about 84nm, the maximum particle size is not more than 140nm, and the main distribution interval of the particle sizes is between 70 and 100 nm.

Example 2

(1) Dissolving 99g of glucose and 0.8g of sodium polyacrylate in 1L of deionized water, and ultrasonically mixing uniformly for 15 min;

(2) transferring 80mL of the uniform solution into a 100mL hydrothermal kettle, sealing, placing in a 220 ℃ oven for hydrothermal treatment for 2h, and naturally cooling to room temperature after the reaction is finished;

(3) taking out the product in the hydrothermal kettle, centrifuging for 8min at 11000r/min, washing for three times by using deionized water and ethanol respectively, and drying in a vacuum oven at 60 ℃;

(4) and (4) carrying out no treatment on the product obtained in the step (3).

FIG. 3 is a scanning electron micrograph of a carbon sphere obtained in example 2. As can be seen from the figure, the carbon spheres have uniform size and good dispersibility, the average particle size is about 104nm, the maximum particle size is not more than 150nm, and the main distribution interval of the particle sizes is 94-108 nm. While the Zeta potential values of table 1 indicate that the surface is negatively charged. The infrared spectrum of fig. 9 shows that the surface contains oxygen-containing functional groups.

Example 3

(1) Dissolving 99g of glucose and 0.2g of sodium polyacrylate in 1L of deionized water, and ultrasonically mixing uniformly for 15 min;

(2) transferring 80mL of the uniform solution into a 100mL hydrothermal kettle, sealing, placing in a 190 ℃ oven for hydrothermal treatment for 5 hours, and naturally cooling to room temperature after the reaction is finished;

(3) taking out the product in the hydrothermal kettle, centrifuging for 8min at 11000r/min, washing for three times by using deionized water and ethanol respectively, and drying in a vacuum oven at 80 ℃;

(4) putting the synthesized product in 20mL of ethanol and 6mol/L of HNO₃In the mixed solution of the aqueous solution, wherein ethanol and HNO₃The volume ratio of the aqueous solution is 1: 2. standing at 25 deg.C for 24 h.

(5) And (3) centrifuging the product obtained in the step (4) for 8min at 11000r/min, washing twice with deionized water and absolute ethyl alcohol respectively, drying in a vacuum oven at 60 ℃, and grinding to obtain the carbon spheres finally.

FIG. 4 is a scanning electron microscope image of the carbon spheres obtained in example 3, which shows that the carbon spheres have uniform size and good dispersibility, the average particle size is about 157nm, the maximum particle size is 260nm, and the main particle size is 120-180 nm. Meanwhile, the Zeta potential values in Table 1 show that the surface negative charge of the carbon spheres after modification treatment is increased compared with the carbon spheres synthesized in example 2. The infrared spectrum of fig. 9 shows that the surface contains abundant oxygen-containing functional groups.

Example 4

(1) Dissolving 150g of glucose and 1g of PEG10000 in 1L of deionized water, and ultrasonically mixing uniformly for 15 min;

(2) transferring 80mL of the uniform solution into a 100mL hydrothermal kettle, sealing, placing in a 190 ℃ oven for hydrothermal for 8 hours, and naturally cooling to room temperature after the reaction is finished;

(3) taking out the product in the hydrothermal kettle, centrifuging for 8min at 11000r/min, washing for three times by using deionized water and ethanol respectively, and drying in a vacuum oven at 60 ℃;

(4) putting the synthesized product into a mixed solution of 10mL of dichloromethane and 1mol/L of NaOH aqueous solution, wherein the volume ratio of the dichloromethane to the NaOH aqueous solution is 1: 9. standing at 25 deg.C for 24 h.

(5) And (4) centrifuging the product obtained in the step (4) for 8min at 11000r/min, washing twice with deionized water and absolute ethyl alcohol respectively, drying in a vacuum oven at 60 ℃, and grinding to obtain the carbon spheres finally.

FIG. 5 is a scanning electron micrograph of the carbon spheres obtained in example 4, which shows that the carbon spheres have uniform size and good dispersibility, the average particle size is about 140nm, the maximum particle size is 240nm, and the main particle size is 100-140 nm. Meanwhile, as shown by the Zeta potential values of table 1, the surface negative charge is increased compared with the carbon spheres synthesized in example 2. The infrared spectrum of fig. 9 shows that the surface contains abundant oxygen-containing functional groups.

Example 5

(1) Dissolving 59.4g of glucose and 0.5g of citric acid in 1L of deionized water, and ultrasonically mixing uniformly for 15 min;

(2) transferring 80mL of the uniform solution into a 100mL hydrothermal kettle, sealing, placing in a 190 ℃ oven for hydrothermal treatment for 4 hours, and naturally cooling to room temperature after the reaction is finished;

(3) taking out the product in the hydrothermal kettle, centrifuging for 8min at 11000r/min, washing for three times by using deionized water and ethanol respectively, and drying in a vacuum oven at 60 ℃;

(4) and putting 1g of the synthesized product into a mixed solution of 100mL of ethanol and 1mol/L of NaOH aqueous solution, wherein the volume ratio of the ethanol to the NaOH aqueous solution is 1: 5. refluxing and stirring at 100 ℃ for 3h, standing for 12h, concentrating by using a rotary evaporation instrument, and drying the residual steaming liquid in a vacuum oven at 60 ℃; .

(5) And (4) centrifuging the product obtained in the step (4) for 8min at 11000r/min, washing twice with deionized water and absolute ethyl alcohol respectively, and drying in a vacuum oven at 60 ℃ to finally obtain the carbon sphere material.

FIG. 6 is a scanning electron micrograph of the carbon spheres obtained in example 5, and it can be seen from the micrograph that the carbon spheres obtained in example 5 have uniform size and good dispersibility, the average particle size is about 160nm, the maximum particle size is 260nm, and the main particle size distribution is 160 to 180 nm. Meanwhile, compared with the carbon spheres synthesized in example 2, as can be seen from table 1, the surface negative charge is increased, and the surface contains rich oxygen-containing functional groups.

Example 6Zeta potential test

The Zeta potential of the carbon spheres obtained in the examples was measured by electrophoresis, and the data are shown in table 1.

TABLE 1 Zeta potential values of carbon spheres

As shown in Table 1, the Zeta potential values on the surfaces of the carbon spheres are reduced by modifying the hydrothermal carbon sphere materials (examples 3-5), which indicates that the number of negatively charged functional groups on the surfaces is increased, and the negative charges on the surfaces are all greatly increased.

Comparative example 1

The preparation method is the same as that of example 1, the only difference is that PEG10000 is replaced by P123, the morphology graph of the obtained carbon spheres is shown in figure 7, and it can be seen that the carbon spheres are seriously agglomerated, and dispersed small-size carbon spheres cannot be obtained.

Comparative example 2

The preparation was identical to example 1, with the only difference that no structure-regulating agent was added. The obtained topography of the carbon spheres is shown in fig. 8, and it can be seen that under the experimental conditions, the final synthetic material has irregular shape and serious adhesion.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims (10)

Translated fromChinese

1.一种碳球材料的制备方法，其特征在于，包括：1. a preparation method of carbon ball material, is characterized in that, comprises:对含有碳源、结构调控剂的水溶液进行水热反应，得到碳球材料；Hydrothermal reaction is carried out on the aqueous solution containing carbon source and structure regulator to obtain carbon ball material;其中，所述结构调控剂为聚乙二醇、聚丙烯酸钠、柠檬酸、硬脂酸、软脂酸、十二烷基苯磺酸中的至少一种。Wherein, the structure regulator is at least one of polyethylene glycol, sodium polyacrylate, citric acid, stearic acid, palmitic acid, and dodecylbenzenesulfonic acid.2.根据权利要求1所述的碳球材料的制备方法，其特征在于，所述水溶液中碳源的浓度为0.2～1mol/L；2. The preparation method of carbon ball material according to claim 1, wherein the concentration of the carbon source in the aqueous solution is 0.2-1 mol/L;优选地，所述结构调控剂的质量为碳源质量的0.1～1％；Preferably, the mass of the structure regulator is 0.1-1% of the mass of the carbon source;优选地，所述碳源选自葡萄糖、果糖、蔗糖中的至少一种。Preferably, the carbon source is selected from at least one of glucose, fructose and sucrose.3.根据权利要求1所述的碳球材料的制备方法，其特征在于，所述水热反应的具体条件包括：3. The preparation method of carbon ball material according to claim 1, is characterized in that, the concrete condition of described hydrothermal reaction comprises:反应温度为185～220℃；The reaction temperature is 185～220 ℃;反应时间为2～12h。The reaction time is 2～12h.4.根据权利要求1所述的碳球材料的制备方法，其特征在于，得到碳球材料后，还包括：4. the preparation method of carbon ball material according to claim 1, is characterized in that, after obtaining carbon ball material, also comprises:将所述碳球材料置于改性溶液中进行改性反应，得到改性碳球材料。The carbon ball material is placed in a modification solution to carry out a modification reaction to obtain a modified carbon ball material.5.根据权利要求4所述的碳球材料的制备方法，其特征在于，所述改性溶液包括液体A和液体B；5. The preparation method of carbon ball material according to claim 4, is characterized in that, described modification solution comprises liquid A and liquid B;其中液体A选自甲醇、乙醇、丙酮、二氯甲烷中的至少一种；Wherein liquid A is selected from at least one in methanol, ethanol, acetone, methylene chloride;优选地，所述液体B为酸或碱的水溶液；Preferably, the liquid B is an acid or alkali aqueous solution;优选地，所述酸为盐酸、硫酸、硝酸、磷酸中的至少一种；Preferably, the acid is at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid;优选地，所述碱为碱金属氢氧化物。Preferably, the base is an alkali metal hydroxide.6.根据权利要求5所述的碳球材料的制备方法，其特征在于，所述液体A和液体B的体积比为1：2～10；6 . The preparation method of carbon ball material according to claim 5 , wherein the volume ratio of the liquid A and the liquid B is 1:2-10; 6 .优选地，所述液体B的浓度为1～6mol/L，其中，液体B的摩尔量以液体B中对应加入的酸、碱化合物的摩尔量计。Preferably, the concentration of the liquid B is 1-6 mol/L, wherein the molar amount of the liquid B is calculated by the molar amount of the acid and alkali compounds added in the liquid B correspondingly.7.根据权利要求4所述的碳球材料的制备方法，其特征在于，所述改性反应的具体条件包括：7. The preparation method of carbon ball material according to claim 4, is characterized in that, the concrete condition of described modification reaction comprises:反应温度为25～180℃，反应时间为3～24h。The reaction temperature is 25～180℃, and the reaction time is 3～24h.8.根据权利要求1所述的碳球材料的制备方法，其特征在于，所述碳球材料的粒径为50～200nm；8. The preparation method of carbon ball material according to claim 1, wherein the particle size of the carbon ball material is 50-200 nm;优选地，所述碳球材料的粒径为50～140nm。Preferably, the particle size of the carbon ball material is 50-140 nm.9.权利要求1～8任一项所述方法制备得到的碳球材料。9. The carbon ball material prepared by the method according to any one of claims 1 to 8.10.权利要求1～8任一项所述方法制备得到的碳球材料作为模板剂在制备空心球材料中的应用、作为吸附剂在吸附重金属离子中的应用、作为催化剂载体负载贵金属在催化领域中的应用。10. Application of the carbon sphere material prepared by the method according to any one of claims 1 to 8 as a template agent in the preparation of hollow sphere materials, as an adsorbent in the adsorption of heavy metal ions, and as a catalyst carrier supporting precious metals in the field of catalysis applications in .

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