CN115382533A - Method for directly preparing and molding spherical metal oxide-based catalyst - Google Patents

Method for directly preparing and molding spherical metal oxide-based catalyst Download PDF

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CN115382533A
CN115382533A CN202210376586.6A CN202210376586A CN115382533A CN 115382533 A CN115382533 A CN 115382533A CN 202210376586 A CN202210376586 A CN 202210376586A CN 115382533 A CN115382533 A CN 115382533A
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spherical
catalyst
metal salt
stirring
water
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沈张锋
王燕刚
李溪
邹旭晖
杨洋
曹勇勇
夏启能
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Jiaxing University
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Abstract

The invention provides a method for directly preparing and molding a spherical metal oxide-based catalyst, which comprises the steps of preparing hydrogel containing metal salt, injection precipitation molding, cleaning, freeze drying, calcining and the like. According to the method, the spherical granular metal oxide-based catalyst is obtained by coprecipitation of hydrogel formed by chitosan, dopamine and metal salt in an alkaline solution, the catalyst retains active sites and has a large specific surface area and pore volume, damage to the active sites in the post-forming process of the catalyst is avoided, and the preparation cost is reduced.

Description

Method for directly preparing and molding spherical metal oxide-based catalyst
Technical Field
The invention relates to the technical field of preparation of catalytic materials, in particular to a method for directly preparing and molding a spherical metal oxide based catalyst.
Background
The catalyst molding is an important link for ensuring that the catalyst can be put into practical production. The efficiency, strength, lifetime and surface active sites of the catalyst are important properties which depend to a large extent on the shaping procedure. The characteristics of catalyst particle size, shape, surface properties, etc. determine the hydrodynamic operating conditions within the reactor, the production capacity of the reactor and the process selectivity. The molding process can provide the granular catalyst with proper shape, size and mechanical strength based on the catalytic reaction and apparatus requirement, and the catalyst has high activity and selectivity and long service life. Meanwhile, the molding operation strengthens the characteristics of a multiphase reaction process, reduces the pressure drop generated by fluid flow, prevents channeling and obtains uniform fluid flow.
Metal oxide-based catalysts are widely used in industry, and are generally complex oxides in which at least one of the components is a transition metal oxide, and the components may interact with each other depending on conditions. The mechanism of catalytic action of metal oxides is largely divided into three. One is to use the band structure of the semiconductor, e.g. N x Carrying out decomposition catalytic reaction on O; second, use the article latticeThe catalytic action of oxygen realizes selective oxidation, such as methane selective oxidation to prepare synthesis gas, methanol or formaldehyde, methane oxidative coupling to prepare ethylene and ethane, butane selective oxidation to prepare maleic anhydride and the like; thirdly, the acidic catalysis of the surface of the metal oxide, such as isomerization reaction, dehydration reaction, dehydrohalogenation reaction, polymerization reaction, esterification reaction and the like, is utilized. The forming process of the metal oxide based catalyst involves more influencing factors, which can have important influence on the above catalytic action. The common catalyst forming methods include compression forming, extrusion forming, rotation forming, spray forming and the like, and the forming processes usually need additional instruments and equipment, and are relatively complex in technological process. For example, most of the existing oxide forming needs to add a binder and a strong acid to achieve a certain strength, however, the strong acid (such as nitric acid) has strong oxidizability and corrosiveness to damage the active sites of the catalyst, and in addition, the addition of the binder and the high-temperature calcination treatment further damage the pore structure of the catalyst and cover the active sites, thereby reducing the activity of the catalyst.
Disclosure of Invention
In view of the above, the present invention provides a method for directly preparing and molding a spherical metal oxide-based catalyst, which uses a method of co-precipitating a hydrogel formed from chitosan, dopamine and a metal salt in an alkaline solution to obtain a spherical and granular metal oxide-based catalyst, which retains active sites and has a large specific surface area and pore volume.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a method for directly preparing and molding a spherical metal oxide-based catalyst comprises the following steps: s1, dissolving chitosan in 1-3% (v/v) acetic acid solution, adding dopamine hydrochloride, continuously stirring to form uniform colloidal solution, adding water-soluble metal salt, and stirring until the metal salt is completely dissolved to form hydrogel containing metal salt;
based on 100 percent of the weight of the acetic acid solution, the addition amount of the chitosan is 1 to 3 percent, the addition amount of the dopamine hydrochloride is 0.1 to 0.3 percent, and the addition amount of the water-soluble metal salt is 4 to 10 percent;
s2, dropping the hydrogel obtained in the step S1 into an alkaline solution through an injector under stirring to form spherical gel particle precipitates, stirring for 1-2h, and filtering to obtain spherical gel particles;
s3, washing the spherical gel particles obtained in the step S2 to be neutral by water, and freeze-drying to obtain spherical particles;
and S4, calcining the spherical particles obtained in the step S3, and cooling to obtain the spherical metal oxide based catalyst.
The method for directly preparing and molding the spherical metal oxide-based catalyst comprises the steps of preparing hydrogel containing metal salt, injection precipitation molding, cleaning, freeze drying, calcining and the like. The preparation method of the invention can be directly molded in the preparation process of the catalyst, avoids the damage to active sites in the post-molding process of the catalyst, and can effectively improve the specific surface area of the metal oxide based catalyst and reduce the preparation cost.
Preferably, the deacetylation degree of the chitosan in S1 is 85% to 95%. The higher the degree of deacetylation, the more free amino groups are present in the molecular chain and the better the solubility in acid.
Preferably, the stirring speed in S1 is 500-800rpm, and the stirring speed in S2 is 100-300 rpm; and in S3, the freeze-drying temperature is-40 to-50 ℃, and the drying time is 12 to 24 hours.
Preferably, in S1, the water-soluble metal salt is selected from In (NO) 3 ) 3 ·H 2 O，ZrO(NO 3 ) 2 ·xH 2 O，Co(NO 3 ) 2 ·6H 2 O，Cu(NO 3 ) 2 ·3H 2 O，Zn(CH 3 COO) 2 ·2H 2 O，Zn(NO 3 ) 2 ·6H 2 O，Ni(NO 3 ) 2 ·6H 2 O，Fe(NO 3 ) 3 ·9H 2 Two or more kinds of O. Preferably, when there are two water-soluble metal salts, the molar ratio of the two water-soluble metal salts is 1: 1 to 8. Furthermore, when the two water-soluble metal salts are used, the molar ratio of the two water-soluble metal salts is 1: 1-4.
Preferably, in S2, the alkaline solution is a NaOH solution or a KOH solution with a concentration of 25-30% (w/v).
Preferably, in S2, the syringe volume is 1 to 10ml, and the needle diameter is 0.50 to 1.2mm.
Preferably, in S4, the calcination is carried out in the atmosphere of air, oxygen and inert gas, the gas flow rate is 20-100 mL/min, the temperature rise rate is 1-10 ℃/min, the calcination temperature is 450-900 ℃, and the calcination time is 2-5 h.
Preferably, the inert gas is selected from one or more of argon, helium and nitrogen.
Compared with the prior art, the method for directly preparing and molding the spherical metal oxide based catalyst provided by the invention takes chitosan, dopamine and soluble metal salt as raw materials, utilizes the self-polymerization and precipitation of the formed hydrogel under the alkaline environment to form spherical particles, and obtains the spherical metal oxide based catalyst by freeze drying and calcining the obtained spherical particles. The method can avoid the reduction of the active sites of the catalyst caused by the post-forming of the catalyst, and the treatment process does not need to additionally add strong acid and a bonding agent, so that the pore structure of the catalyst is not damaged, and the obtained spherical catalyst has higher specific surface area and pore volume.
Drawings
FIG. 1 is a photograph of an indium oxide/zirconium oxide composite spherical catalyst obtained in example 1 of the present invention;
FIG. 2 is an XRD pattern of an indium oxide/zirconium oxide composite sphere catalyst obtained in example 1 of the present invention;
FIG. 3 is a nitrogen desorption and pore size distribution diagram of the indium oxide/zirconium oxide composite spherical catalyst obtained in example 1 of the present invention, wherein (a) is a nitrogen desorption curve and (b) is a pore size distribution diagram;
FIG. 4 is a photograph and analysis results of a powdered indium oxide/zirconium oxide catalyst obtained by a conventional coprecipitation method in example 1 of the present invention, wherein (a) the actual photograph of the catalyst, (b) the nitrogen desorption curve of the catalyst, and (c) the pore size distribution of the catalyst;
FIG. 5 is a photograph of a cobalt oxide/copper oxide composite sphere-type catalyst obtained in example 2 of the present invention;
FIG. 6 is a nitrogen desorption and pore size distribution diagram of the cobalt oxide/copper oxide composite spherical catalyst obtained in example 2 of the present invention, wherein (a) is a nitrogen desorption curve and (b) is a pore size distribution diagram;
FIG. 7 is a photograph of a zinc oxide/zirconium oxide composite spherical catalyst obtained in example 3 of the present invention;
FIG. 8 is a nitrogen desorption and pore size distribution diagram of a zinc oxide/zirconium oxide composite spherical catalyst obtained in example 3 of the present invention, wherein (a) is a nitrogen desorption curve and (b) is a pore size distribution diagram; (ii) a
FIG. 9 is a photograph of a zinc oxide/cobalt oxide composite spherical catalyst obtained in example 4 of the present invention;
FIG. 10 is a nitrogen desorption and pore size distribution diagram of a zinc oxide/cobalt oxide composite spherical catalyst obtained in example 4 of the present invention, wherein (a) is a nitrogen desorption curve and (b) is a pore size distribution diagram;
FIG. 11 is a photograph of a nickel oxide/zirconium oxide composite sphere catalyst obtained in example 5 of the present invention;
FIG. 12 shows the nitrogen desorption and pore size distribution diagrams of the nickel oxide/zirconia composite spherical catalyst obtained in example 5 of the present invention, wherein (a) is a nitrogen desorption curve and (b) is a pore size distribution diagram.
FIG. 13 is a graph comparing the effect of the indium oxide/zirconium oxide composite spherical catalyst obtained in example 1 of the present invention on the hydrogenation of carbon dioxide by the powdery indium oxide/zirconium oxide catalyst.
Detailed Description
The technical solution of the present invention will be further specifically described below by way of specific examples. It is to be understood that the practice of the invention is not limited to the following examples, and that any variations and/or modifications may be made thereto without departing from the scope of the invention.
In the present invention, all parts and percentages are by weight, unless otherwise specified, and the equipment and materials used are commercially available or commonly used in the art. The methods in the following examples are conventional in the art unless otherwise specified.
Example 1
A method for directly preparing and molding a spherical metal oxide-based catalyst comprises the following steps:
1) 50ml of 1%v/v acetic acid solution is prepared, and 1g of chitosan (degree of deacetylation 95%) and 0.1g of dopamine hydrochloride are weighed.
2) Adding chitosan into the acetic acid solution, stirring at the rotation speed of 800rpm to completely dissolve the chitosan, then adding dopamine hydrochloride, continuously stirring to completely dissolve the dopamine hydrochloride, and stirring at room temperature to form uniform hydrogel.
3) Weighing In (NO) 3 ) 3 ·H 2 O 1.28g，ZrO(NO 3 ) 2 ·xH 2 O 2.77g。
4) Adding the metal salt into the prepared hydrogel, and fully stirring to completely dissolve the metal salt to form uniform hydrogel containing the metal salt.
5) 30% w/v of NaOH solution (200 ml) was prepared, and the mixture was stirred at 100 rpm.
6) The hydrogel containing the metal salt was aspirated by a 1ml syringe and added dropwise to the above NaOH solution to form gel spherical particles with a needle diameter of 0.60mm.
7) And (3) after the hydrogel containing the metal salt is completely dripped, keeping the rotating speed of 100rpm and continuing stirring for 1h, then filtering the spherical particles, and washing the spherical particles with deionized water until the spherical particles are neutral.
8) Freezing the obtained spherical particles at-20 deg.C, and drying in a freeze drier at-40 deg.C for 24 hr.
9) And calcining the spherical particles in a tubular furnace in the atmosphere of air at the gas flow rate of 100ml/min at the temperature rise rate of 5 ℃/min at the calcining temperature of 500 ℃ for 3h to obtain the indium oxide/zirconium oxide composite spherical catalyst.
The photograph of the indium oxide/zirconium oxide composite spherical catalyst is shown in FIG. 1, in which FIG. 1 shows that the catalyst particles have a uniform particle size, with an average of 1mm, and in which the XRD pattern of FIG. 2 shows that the catalyst has excellent oxidationThe crystal phases of indium and zirconium oxide, FIG. 3 showing the specific surface area of the catalyst at 54.8m 2 Per g, pore volume 0.315cm 3 /g。
For comparison, a powdered indium oxide/zirconium oxide catalyst was prepared by a conventional co-precipitation method, as follows: weighing In (NO) 3 ) 3 ·H 2 O 1.28g，ZrO(NO 3 ) 2 ·xH 2 O2.77 g was dissolved in 100ml of water as solution A, 25ml of 25% ammonia water and 75ml of ethanol were mixed as solution B, and the solution B was slowly dropped into the solution A until the pH reached 9.2, suction-filtered, washed to neutrality, dried at 60 ℃ and then calcined at 500 ℃ for 2 hours to obtain a pale yellow powder, and the photograph is shown in FIG. 4 a. FIG. 4b shows that the specific surface area of the powdered indium oxide/zirconium oxide catalyst is 8.3m 2 Per g, pore volume 0.032cm 3 (iv) less than the indium oxide/zirconium oxide composite spherical catalyst.
Example 2
A method for directly preparing and molding a spherical metal oxide-based catalyst comprises the following steps:
1) 50ml of 2%v/v acetic acid solution is prepared, and 1g of chitosan (degree of deacetylation is 90%) and 0.05g of dopamine hydrochloride are weighed.
2) Adding chitosan into the acetic acid solution, stirring at the rotation speed of 500rpm to completely dissolve the chitosan, then adding dopamine hydrochloride, continuously stirring to completely dissolve the dopamine hydrochloride, and stirring at room temperature to form uniform hydrogel.
3) Weighing Co (NO) 3 ) 2 ·6H 2 O 1.12g，Cu(NO 3 ) 2 ·3H 2 O 0.96g。
4) Adding the metal salt into the prepared hydrogel, and fully stirring to completely dissolve the metal salt to form uniform hydrogel containing the metal salt.
5) 25% w/v of KOH solution (200 ml) was prepared, and the mixture was stirred at 200 rpm.
6) The hydrogel containing the metal salt was aspirated by a 5ml syringe and added dropwise to the above KOH solution to form gel spherical particles with a needle diameter of 0.60mm.
7) And (3) after the hydrogel containing the metal salt is completely dripped, continuously stirring for 1h at the rotating speed of 200rpm, filtering the spherical particles, and washing with deionized water until the spherical particles are neutral.
8) Freezing the obtained spherical particles at-20 deg.C, and drying in a freeze dryer at-50 deg.C for 12 hr.
9) And calcining the spherical particles in a tubular furnace in the atmosphere of oxygen at the gas flow rate of 20ml/min at the temperature rise rate of 1 ℃/min at the calcining temperature of 450 ℃ for 2h to obtain the cobalt oxide/copper oxide composite spherical catalyst.
The photograph of the cobalt oxide/copper oxide composite spherical catalyst is shown in FIG. 5, FIG. 5 shows that the catalyst particles have uniform particle size, the average particle size is 1-1.5 mm, FIG. 6 shows that the specific surface area of the catalyst is 25.8m 2 Per g, pore volume 0.197cm 3 /g。
Example 3
A method for directly preparing and molding a spherical metal oxide-based catalyst comprises the following steps:
1) 50ml of 3%v/v acetic acid solution is prepared, and 1.5g of chitosan (degree of deacetylation of 85%) and 0.15g of dopamine hydrochloride are weighed.
2) Adding chitosan into the acetic acid solution, stirring at 700rpm to dissolve completely, adding dopamine hydrochloride, stirring to dissolve completely, and stirring at room temperature to form uniform hydrogel.
3) Weighing Zn (CH) 3 COO) 2 ·2H 2 O 1.75g，ZrO(NO 3 ) 2 ·xH 2 O 2.8g。
4) Adding the metal salt into the prepared hydrogel, and fully stirring to completely dissolve the metal salt to form uniform hydrogel containing the metal salt.
5) Preparation 28% of 200ml of NaOH solution w/v, and stirring was maintained at 300 rpm.
6) The hydrogel containing the metal salt was sucked up with a 10ml syringe and added dropwise to the above NaOH solution to form gel-ball-type particles, using a needle having a diameter of 0.50mm.
7) And (3) after the hydrogel containing the metal salt is completely dripped, keeping the rotating speed of 300rpm and continuing stirring for 1h, then filtering the spherical particles, and washing the spherical particles with deionized water until the spherical particles are neutral.
8) Freezing the obtained spherical particles at-20 deg.C, and drying in a freeze dryer at-50 deg.C for 16h.
9) And calcining the spherical particles in a tubular furnace in the atmosphere of air at the gas flow rate of 80ml/min at the temperature rise rate of 10 ℃/min at the calcining temperature of 600 ℃ for 4h to obtain the zinc oxide/zirconium oxide composite spherical catalyst.
The photograph of the zinc oxide/zirconium oxide composite spherical catalyst is shown in FIG. 7, in which FIG. 7 shows that the catalyst particles have a uniform particle diameter, with an average of 0.8mm, and FIG. 8 shows that the specific surface area of the catalyst is 53.9m 2 Per g, pore volume 0.102cm 3 /g。
Example 4
A method for directly preparing and molding a spherical metal oxide-based catalyst comprises the following steps:
1) 50ml of 1%v/v acetic acid solution is prepared, and 1g of chitosan (degree of deacetylation 95%) and 0.1g of dopamine hydrochloride are weighed.
2) Adding chitosan into the acetic acid solution, stirring at 600rpm to dissolve completely, adding dopamine hydrochloride, and stirring at room temperature to obtain uniform hydrogel.
3) Weighing Zn (NO) 3 ) 2 ·6H 2 O 1.75g，Co(NO 3 ) 2 ·6H 2 O 1.20g。
4) Adding the metal salt into the prepared hydrogel, and fully stirring to completely dissolve the metal salt to form uniform hydrogel containing the metal salt.
5) Preparation 28% of 200ml of NaOH solution w/v, and stirring was maintained at a rotation speed of 150 rpm.
6) The hydrogel containing the metal salt was sucked up with a 1ml syringe and added dropwise to the above NaOH solution to form gel spherical particles, using a needle having a diameter of 0.60mm.
7) And (3) after the hydrogel containing the metal salt is completely dripped, keeping the rotating speed of 150rpm and continuing stirring for 1h, then filtering the spherical particles, and washing the spherical particles with deionized water until the spherical particles are neutral.
8) Freezing the obtained spherical particles at-20 deg.C, and drying in a freeze dryer at-50 deg.C for 16h.
9) And calcining the spherical particles in a tubular furnace in the atmosphere of air at the gas flow rate of 100ml/min at the temperature rise rate of 5 ℃/min at the calcining temperature of 500 ℃ for 5h to obtain the zinc oxide/cobalt oxide composite spherical catalyst.
The photograph of the zinc oxide/cobalt oxide composite spherical catalyst is shown in FIG. 9, in which FIG. 9 shows that the catalyst particles have a uniform particle size, with an average of 1.2mm, and FIG. 10 shows that the specific surface area of the catalyst is 16.9m 2 Per g, pore volume 0.151cm 3 /g。
Example 5
A method for directly preparing and molding a spherical metal oxide-based catalyst comprises the following steps:
1) 50ml of 1%v/v acetic acid solution is prepared, and 1.5g of chitosan (degree of deacetylation 95%) and 0.1g of dopamine hydrochloride are weighed.
2) Adding chitosan into the acetic acid solution, stirring at the rotation speed of 800rpm to completely dissolve the chitosan, then adding dopamine hydrochloride, continuously stirring to completely dissolve the dopamine hydrochloride, and stirring at room temperature to form uniform hydrogel.
3) Weighing Ni (NO) 3 ) 2 ·6H 2 O 1.16g，ZrO(NO 3 ) 2 ·xH 2 O 2.77g。
4) Adding the metal salt into the prepared hydrogel, and fully stirring to completely dissolve the metal salt to form uniform hydrogel containing the metal salt.
5) Preparation 26% of 200ml of NaOH solution w/v, and stirring was maintained at a rotation speed of 250 rpm.
6) The hydrogel containing the metal salt was aspirated by a 1ml syringe and added dropwise to the above NaOH solution to form gel spherical particles with a needle diameter of 0.70mm.
7) And (3) after the hydrogel containing the metal salt is completely dripped, continuously stirring for 1h at the rotating speed of 250rpm, filtering the spherical particles, and washing with deionized water until the spherical particles are neutral.
8) Freezing the obtained spherical particles at-20 deg.C, and drying in a freeze dryer at-50 deg.C for 24 hr.
9) And calcining the spherical particles in a tubular furnace in the atmosphere of air at the gas flow rate of 50ml/min at the temperature rise rate of 10 ℃/min at the calcining temperature of 550 ℃ for 2h to obtain the nickel oxide/zirconium oxide composite spherical catalyst.
The photograph of the nickel oxide/zirconia composite spherical catalyst is shown in FIG. 11, in which FIG. 11 shows that the catalyst particles have a uniform particle diameter, the average particle diameter is 1.5mm, and FIG. 12 shows that the specific surface area of the catalyst is 60.1m 2 Per g, pore volume 0.197cm 3 /g。
Example 6
A method for directly preparing and molding a spherical metal oxide-based catalyst comprises the following steps:
1) 50ml of 1%v/v acetic acid solution is prepared, and 1.5g of chitosan (degree of deacetylation is 90%) and 0.05g of dopamine hydrochloride are weighed.
2) Adding chitosan into the acetic acid solution, stirring at 800rpm to dissolve completely, adding dopamine hydrochloride, stirring to dissolve completely, and stirring at room temperature to form uniform hydrogel.
3) Weighing Cu (NO) 3 ) 2 ·3H 2 O 1.10g，Fe(NO 3 ) 3 ·9H 2 O 1.45g，ZrO(NO 3 ) 2 ·xH 2 O 3.0g。
4) Adding the metal salt into the prepared hydrogel, and fully stirring to completely dissolve the metal salt to form uniform hydrogel containing the metal salt.
5) 30% w/v KOH solution (200 ml) was prepared, and the mixture was stirred at 100 rpm.
6) The hydrogel containing the metal salt was aspirated by a 10ml syringe and added dropwise to the above KOH solution to form gel-spherical particles with a needle diameter of 1.2mm.
7) And (3) after the hydrogel containing the metal salt is completely dripped, continuously stirring for 1 hour at the rotating speed of 100rpm, filtering the spherical particles, and washing with deionized water until the spherical particles are neutral.
8) Freezing the obtained spherical particles at-20 deg.C, and drying in a freeze dryer at-50 deg.C for 20 hr.
9) And calcining the spherical particles in a tubular furnace in the atmosphere of nitrogen at the gas flow rate of 80ml/min at the temperature rise rate of 2 ℃/min at the calcining temperature of 800 ℃ for 2h to obtain the carbon-doped Cu-Fe-zirconia composite spherical catalyst.
Example 7
A method for directly preparing and molding a spherical metal oxide-based catalyst comprises the following steps:
1) 50ml of 2%v/v acetic acid solution is prepared, and 1g of chitosan (degree of deacetylation 95%) and 0.15g of dopamine hydrochloride are weighed.
2) Adding chitosan into the acetic acid solution, stirring at the rotation speed of 800rpm to completely dissolve the chitosan, then adding dopamine hydrochloride, continuously stirring to completely dissolve the dopamine hydrochloride, and stirring at room temperature to form uniform hydrogel.
3) Weighing Ni (NO) 3 ) 2 ·6H 2 O 0.3g，Fe(NO 3 ) 3 ·9H 2 O 1.0g，ZrO(NO 3 ) 2 ·xH 2 O 2.0g。
4) Adding the metal salt into the prepared hydrogel, and fully stirring to completely dissolve the metal salt to form uniform hydrogel containing the metal salt.
5) 30% w/v of NaOH solution (200 ml) was prepared, and the mixture was stirred at 150 rpm.
6) The hydrogel containing the metal salt was sucked up with a 5ml syringe and added dropwise to the above NaOH solution to form gel spherical particles with a needle diameter of 0.7mm.
7) And (3) after the hydrogel containing the metal salt is completely dripped, keeping the rotating speed of 150rpm and continuing stirring for 1h, then filtering the spherical particles, and washing the spherical particles with deionized water until the spherical particles are neutral.
8) Freezing the obtained spherical particles at-20 deg.C, and drying in a freeze dryer at-40 deg.C for 16h.
9) And calcining the spherical particles in a tubular furnace in the atmosphere of argon at the gas flow rate of 20ml/min at the temperature rise rate of 5 ℃/min at the calcining temperature of 900 ℃ for 4h to obtain the carbon-doped Ni-Fe-zirconia composite spherical catalyst.
Fig. 13 shows the effect of the indium oxide/zirconium oxide composite spherical catalyst and the powdered indium oxide/zirconium oxide catalyst obtained in example 1 of the present invention in catalyzing the hydrogenation of carbon dioxide, wherein the reaction conditions are as follows: composition of the reaction gas CO 2 ：H 2 : ar =1:4:5, the reaction pressure is 3MPa, and the reaction temperature is 250-400 ℃. It can be seen from the figure that the conversion rate of carbon dioxide on the indium oxide/zirconium oxide composite ball catalyst is higher than that of the powdered indium oxide/zirconium oxide catalyst at all temperatures, which is mainly because the indium oxide/zirconium oxide composite ball catalyst has higher specific surface area and pore volume, and is beneficial to the diffusion and adsorption of reaction gas on the surface of the catalyst. In addition, the selectivity of methanol on the indium oxide/zirconium oxide composite spherical catalyst is higher than that of the powdery indium oxide/zirconium oxide catalyst at 275 ℃, which shows that the method for directly preparing and molding the spherical metal oxide-based catalyst has unique advantages.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The method for directly preparing and molding the spherical metal oxide-based catalyst provided by the invention is described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims (10)

1. A method for directly preparing and molding a spherical metal oxide-based catalyst is characterized by comprising the following steps: the method comprises the following steps:
s1, dissolving chitosan in 1-3% (v/v) acetic acid solution, adding dopamine hydrochloride, continuously stirring to form uniform colloidal solution, adding water-soluble metal salt, and stirring until the metal salt is completely dissolved to form hydrogel containing metal salt;
based on 100 percent of the weight of the acetic acid solution, the adding amount of the chitosan is 1 to 3 percent, the adding amount of the dopamine hydrochloride is 0.1 to 0.3 percent, and the adding amount of the water-soluble metal salt is 4 to 10 percent;
s2, dropping the hydrogel obtained in the step S1 into an alkaline solution through an injector under stirring to form spherical gel particle precipitates, stirring for 1-2h, and filtering to obtain spherical gel particles;
s3, washing the spherical gel particles obtained in the step S2 to be neutral by water, and freeze-drying to obtain spherical particles;
and S4, calcining the spherical particles obtained in the step S3, and cooling to obtain the spherical metal oxide based catalyst.
2. The method of claim 1, wherein: the deacetylation degree of the chitosan in the S1 is 85-95%.
3. The method of claim 1, wherein: the stirring speed in S1 is 500-800rpm, and the stirring speed in S2 is 100-300 rpm; and in S3, the freeze-drying temperature is-40 to-50 ℃, and the drying time is 12 to 24 hours.
4. The method of claim 1, wherein: in S1, the water-soluble metal salt is selected from In (NO) 3 ) 3 ·H 2 O，ZrO(NO 3 ) 2 ·xH 2 O，Co(NO 3 ) 2 ·6H 2 O，Cu(NO 3 ) 2 ·3H 2 O，Zn(CH 3 COO) 2 ·2H 2 O，Zn(NO 3 ) 2 ·6H 2 O，Ni(NO 3 ) 2 ·6H 2 O，Fe(NO 3 ) 3 ·9H 2 Two or more kinds of O.
5. The method of claim 1, wherein: in S2, the alkaline solution is NaOH solution or KOH solution with the concentration of 25-30% (w/v).
6. The method of claim 1, wherein: in S2, the volume of the injector is 1-10 ml, and the diameter of the needle is 0.50-1.2 mm.
7. The method of claim 1, wherein: in S4, the calcination is carried out in the atmosphere of air, oxygen and inert gas, the gas flow rate is 20-100 mL/min, the heating rate is 1-10 ℃/min, the calcination temperature is 450-900 ℃, and the calcination time is 2-5 h.
8. The method of claim 7, wherein: the inert gas is selected from one or more of argon, helium and nitrogen.
9. The method of claim 4, wherein: when the two water-soluble metal salts are used, the molar ratio of the two water-soluble metal salts is 1: 1-8.
10. The method of claim 4, wherein: when the two water-soluble metal salts are used, the molar ratio of the two water-soluble metal salts is 1: 1-4.
CN202210376586.6A 2022-04-11 2022-04-11 Method for directly preparing and molding spherical metal oxide-based catalyst Pending CN115382533A (en)

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Application publication date: 20221125