CN109928433B

CN109928433B - Macroporous iron oxide and synthetic method thereof

Info

Publication number: CN109928433B
Application number: CN201711353696.6A
Authority: CN
Inventors: 范峰; 凌凤香; 张会成; 王少军; 杨春雁
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2017-12-15
Filing date: 2017-12-15
Publication date: 2021-08-06
Anticipated expiration: 2037-12-15
Also published as: CN109928433A

Abstract

The invention provides macroporous iron oxide and a synthesis method thereof, wherein the iron oxide is alpha-iron oxide and has macroporous channels, and the pore diameter of macropores ranges from 50 nm to 1400 nm. The synthesis method comprises the steps of firstly, pretreating a Beta molecular sieve; then mixing the Beta molecular sieve, ferric nitrate and water, and stirring and ultrasonically treating; then carrying out drying treatment and high-temperature treatment; and finally, treating in an alkali solution to obtain macroporous iron oxide. The method does not use expensive organic additives, and the prepared macroporous iron oxide has uniform pore size distribution.

Description

Macroporous iron oxide and synthetic method thereof

Technical Field

The invention belongs to the field of synthesis of porous inorganic materials, and particularly relates to macroporous iron oxide and a synthesis method thereof.

Background

The iron oxide is a cheap and easily-obtained green functional material, and has wide application prospects in various fields such as catalysis, magnetic equipment, sensors, environmental protection, medical diagnosis and treatment, water purification, pollution treatment and the like.

CN102260542 discloses a preparation method of a three-dimensional ordered macroporous iron oxide desulfurizer, which adopts a colloidal crystal template method to prepare a macroporous material, uses a polystyrene microsphere colloidal crystal template as a macroporous template, fills a precursor in gaps of the template, and finally removes the template to obtain the three-dimensional ordered macroporous iron oxide. However, the assembly of the template takes too long and the preparation cost is too high.

CN 101723469A discloses a soft-hard double template method for preparing three-dimensional ordered macroporous iron oxide with mesoporous pore walls, which comprises the steps of dissolving ferric nitrate nonahydrate and a soft template P123 in absolute ethyl alcohol or a mixed solution of absolute methyl alcohol and absolute ethylene glycol under the conditions of normal temperature, normal pressure and ultrasound, infiltrating PMMA microspheres of the hard template in a close-packed arrangement by using the mixed solution, and carrying out suction filtration, drying, programmed heating and roasting on the mixed solution containing PMMA to obtain the three-dimensional ordered macroporous iron oxide with the mesoporous pore walls in a rhombus structure. The patent is characterized in that double templates are used, one is a colloidal crystal template, and the other is a soft template P123, and the preparation cost is too high.

CN102951687A discloses an iron oxide mesoporous microsphere and a preparation method thereof, wherein a precursor solution containing a pore-forming agent is prepared, and then the precursor solution is subjected to spray drying and granulation to obtain microsphere powder; finally, the mesoporous ferric oxide is obtained by roasting. The pore-forming agent used is a high molecular weight polymer.

CN101733102A discloses the preparation of a porous monolithic iron oxide catalyst and discloses a preparation method of macroporous iron oxide. The patent firstly uses alkoxy silane as a silicon source, uses polyethylene glycol as a macroporous template agent and uses ammonia water as a mesoporous template agent to prepare a double-pore silica gel monolithic column template. Then the nitrate solution passes through a silica gel monolithic column, and finally the silica gel is dissolved by sodium hydroxide solution to obtain the monolithic porous iron oxide containing macropores and mesopores.

The analysis shows that the existing preparation method of the macroporous or porous iron oxide material still has the problems of overlong template assembly time consumption, high preparation cost, difficult industrial production, uneven pore distribution of the material, poor physical and chemical properties and the like.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the macroporous iron oxide and the synthesis method thereof.

The invention provides macroporous iron oxide, which has the following characteristics: the alpha-iron oxide is composed of macroporous channels, the pore diameter range of the macropores is 50-1400 nm, the most probable pore diameter D of the macropores is 60-900nm, and the proportion of the macropores in the range of 0.8D-1.2D in the whole macropores is more than 65%. In the macroporous iron oxide, the specific surface area of the macroporous iron oxide is 30-100 m²/g。

The invention provides a synthesis method of macroporous iron oxide, which comprises the following steps:

(1) mixing a Beta molecular sieve with an acid solution, treating at 50-200 ℃ for 1-10 h, then carrying out solid-liquid separation, and washing and drying collected solids;

(2) mixing the treated Beta molecular sieve obtained in the step (1) with a sodium benzoate solution, uniformly mixing, carrying out solid-liquid separation, and drying the collected solid;

(3) uniformly mixing the Beta molecular sieve obtained in the step (2), ferric nitrate and water;

(4) drying the material obtained in the step (3) until the water is completely evaporated;

(5) carrying out high-temperature treatment on the material obtained after drying in the step (4);

(6) and (3) mixing the solid material obtained in the step (5) with alkali liquor, treating for 1-10 h at 100-200 ℃, and then washing and drying to obtain the macroporous iron oxide.

In the method, the crystal size of the Beta molecular sieve is 70-1000 nm, and the Beta molecular sieve can be purchased from a commodity which meets the requirement and sold in the market, and can also be prepared according to the existing method.

In the method, the Beta molecular sieve can be prepared by the following steps: mixing an alkali source, a silicon source, an aluminum source, water and a template agent (TEAOH) according to a molar ratio of 3-8 Na₂O：40～100SiO₂：A1₂O₃：800～1200H₂O: and (3) uniformly mixing 10-30 TEAOH, then placing the mixture into a closed reactor, crystallizing the mixture for 10-60 hours at the temperature of 100-180 ℃, and finally separating, washing and drying the crystallized product to obtain the Beta molecular sieve.

In the above method, the inorganic base is sodium hydroxide; the aluminum source is one or more of sodium aluminate, aluminum sulfate, aluminum chloride and aluminum nitrate; the silicon source is white carbon black and/or silica sol; the templating agent is tetraethylammonium hydroxide.

In the method, the crystallization reaction temperature is 100-180 ℃, the reaction time is 10-60 hours, the preferable reaction temperature is 105-160 ℃, and the reaction time is 20-50 hours.

In the method, the washing is washing by using distilled water; the drying condition is that the treatment is carried out for 5-15 h under the condition of 100-150 ℃, and preferably for 6-12 h under the condition of 110-140 ℃.

In the method, a pretreatment step (1A) is further included before the step (1), the Beta molecular sieve is firstly put into a screening solution, the Beta molecular sieve is naturally settled in the screening solution, when the molecular sieve is settled to the bottom of the screening solution, the screening solution is divided into a plurality of equal sections, such as n equal sections, and the value of n is an odd number larger than 1 (the value of n can be odd numbers such as 3, 5, 7, 9, 11, and the like). If the crystal size of the molecular sieve is relatively uniform, the value of n can be a smaller value, otherwise, a larger value is taken. When the molecular sieve is selected, the molecular sieves in different segments may be selected as required, and it is preferable to select the molecular sieve in the most central segment (for example, 1/3 in the middle when the molecular sieve is divided into three portions and 1/5 in the middle when the molecular sieve is divided into 5 portions), and the molecular sieve thus selected is filtered and dried.

In the method, the screening solution is any one of a propylene glycol aqueous solution and a glycerol aqueous solution, and the concentration of the screening solution is 5-75 wt%, preferably 10-70 wt%; the mass ratio of the screening solution to the Beta molecular sieve is 1-10: 1, preferably 2-8: 1.

In the method, the acid solution in the step (1) is any one of hydrochloric acid, nitric acid and sulfuric acid, and the concentration of the acid solution is 0.1-1 mol/L. The liquid-solid mass ratio of the acid solution to the Beta molecular sieve is 1-10: 1, preferably 2-8: 1.

In the method, the solid-liquid separation in the steps (1) and (2) is any technical means which can realize solid-liquid separation in the field, for example, the solid material is separated from the liquid by adopting filtration.

In the method of the present invention, the washing in step (1) is washing with distilled water; the drying condition in the step (1) is that the treatment is carried out for 5-15 h under the condition of 100-150 ℃, and preferably for 6-12 h under the condition of 110-140 ℃.

In the method, the concentration of the sodium benzoate solution in the step (2) is 2-20 wt%, preferably 3-18 wt%; the liquid-solid mass ratio of the sodium benzoate solution to the Beta molecular sieve is 1-10: 1, preferably 2-8: 1.

In the method, the solid-liquid separation in the step (2) is any technical means which can realize the solid-liquid separation in the field, for example, the solid material is separated from the liquid by adopting filtration, and the solid material is directly dried without washing.

In the method, the drying condition in the step (2) is treatment for 5-15 h at 100-150 ℃, preferably treatment for 6-12 h at 110-140 ℃.

In the method, the mass ratio of the Beta molecular sieve, the ferric nitrate and the water in the step (3) is 0.1-2: 1: 10 to 33, preferably 0.2 to 1.8: 1: 12 to 30.

In the method, the drying temperature in the step (4) is 100-150 ℃.

In the method, the high-temperature treatment temperature in the step (5) is 300-900 ℃, and preferably 400-800 ℃; the treatment time is 1-10 h, preferably 2-8 h.

In the method, the alkali liquor in the step (6) is one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide and other solutions, and the concentration of the alkali liquor is 15-55 wt%, preferably 20-50 wt%; the mass ratio of the alkali liquor to the solid-phase material is 1-10: 1, and preferably 2-8: 1.

In the method, the treatment temperature in the step (6) is 120-180 ℃; the treatment time is 2-8 h.

In the method of the present invention, the washing in step (6) is washing with distilled water; the drying condition in the step (5) is that the treatment is carried out for 5-15 h under the condition of 100-150 ℃, and preferably for 6-12 h under the condition of 110-140 ℃.

In the method, the mixing in the step (1), the step (2), the step (3) and the step (6) can adopt any one of stirring, high-speed shearing, ultrasonic treatment and the like, preferably under the ultrasonic condition, when the ultrasonic treatment is adopted, the treatment time is 10-60 min, preferably 15-55 min, the frequency of the ultrasonic wave is 15KHz-10MHz, and the power is 20-100W/L according to the volume of the solution.

The macroporous iron oxide provided by the invention has rich macropores and can be used as a catalyst, an adsorbent or other functional materials.

Compared with the prior art, the macroporous iron oxide and the synthesis method thereof provided by the invention have the following advantages:

in the synthetic method, the Beta molecular sieve is used as a hard template for preparing the macroporous iron oxide for the first time.

In the method, the Beta molecular sieve is treated by acid, then treated by sodium benzoate and combined with ultrasonic treatment, so that the Beta molecular sieve is more favorably kept in a monodispersed state, the molecular sieve is favorably used for adsorbing a precursor substance on the outer surface of the Beta molecular sieve, the molecular sieve can be more uniformly dispersed in a precursor solution, and the agglomeration of the molecular sieve and the phase separation of the molecular sieve and the precursor are avoided. Solves the technical problems that macroporous iron oxide can not be prepared and only common iron oxide particles can be obtained when the molecular sieve is agglomerated and the molecular sieve and a precursor are separated. In the method, the macroporous ferric oxide prepared by using the Beta molecular sieve treated by the sodium benzoate treated by the acid as the template has higher aperture concentration and more uniform aperture distribution, has more advantages in the separation field, and can finely control the screening of the separated substances according to the nanometer level.

In the preparation method, compared with other types of hard templates, the size of the template of the Beta molecular sieve can be accurately adjusted according to requirements, and the preparation method has high repeatability and low production cost.

Drawings

Fig. 1 is an SEM photograph of the macroporous iron oxide synthesized in example 1.

Detailed Description

The method for preparing the macroporous iron oxide of the present invention will be described in detail below with reference to specific examples, but it is not limited thereto.

Example 1

(1) 0.25 g of sodium hydroxide was dissolved in 40 mL of 25wt% TEAOH and 18 mL of distilled water, and stirred for 30 min. Then, 0.7g of sodium aluminate was added thereto, and stirred for 30 min. Then 12 g of white carbon black is slowly added and stirred for 30 min. Then the mixture is put into a closed reaction kettle and crystallized in an oven for 50 hours at 165 ℃. Then washing the obtained product to be neutral by using distilled water, and then drying the product for 12h at the temperature of 120 ℃ to obtain the Beta molecular sieve.

(2) And (2) putting the Beta molecular sieve obtained in the step (1) into 50 mL of 50wt% propylene glycol solution, naturally settling, taking out 1/3 part solution in the middle of the whole solution when the molecular sieve just settles to the bottom, filtering, and drying at 120 ℃ for 10 h.

(3) Mixing the Beta molecular sieve obtained in the step (2) with 5mL of 0.5moL/L hydrochloric acid, loading the mixture into a closed reactor, treating the mixture for 5 hours at 100 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12 hours at 120 ℃.

(4) Mixing the Beta molecular sieve obtained in the step (3) with 15mL of 10wt% sodium benzoate solution, carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 0.01MHz, and the power is 20W/L according to the volume of the solution; then, after one filtration, the mixture is dried for 12 hours at the temperature of 120 ℃.

(5) And (3) respectively adding 1g of the Beta molecular sieve obtained in the step (4) and 0.91g of ferric nitrate into 20mL of water, uniformly stirring, and carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 0.01MHz, and the power is 20W/L according to the volume of the solution.

(6) Drying the obtained substance of step (5) at 120 deg.C until the water is completely evaporated.

(7) And (4) carrying out constant temperature treatment on the solid substance obtained in the step (6) at 510 ℃ for 5 h.

(8) And (3) mixing the substance obtained in the step (7) with 5mL of 40wt% NaOH solution, loading the mixture into a closed reactor, treating the mixture for 7h at 150 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃ to obtain macroporous iron oxide, wherein the number of the macroporous iron oxide is CL 1. The SEM image of the resulting sample is shown in FIG. 1 as macroporous iron oxide.

Example 2

(1) 0.27 g of sodium hydroxide was dissolved in 12 mL of 25wt% TEAOH and 20mL of distilled water, and stirred for 30 min. Then, 0.7g of sodium aluminate was added thereto, and stirred for 30 min. Then 17 g of white carbon black is slowly added and stirred for 30 min. Then the mixture is put into a closed reaction kettle and crystallized in an oven at 154 ℃ for 20 hours. Then washing the obtained product to be neutral by using distilled water, and then drying the product for 12h at the temperature of 120 ℃ to obtain the Beta molecular sieve.

(2) And (2) putting the Beta molecular sieve obtained in the step (1) into 85 mL of 75wt% glycerol solution, naturally settling, taking out 1/5 part solution in the middle of the whole solution when the molecular sieve just settles to the bottom, filtering, and drying at 120 ℃ for 10 h.

(3) Mixing the Beta molecular sieve obtained in the step (2) with 15mL of hydrochloric acid with the concentration of 1moL/L, loading the mixture into a closed reactor, treating the mixture for 7 hours at the temperature of 60 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12 hours at the temperature of 120 ℃.

(4) Mixing the Beta molecular sieve obtained in the step (3) with 5mL of 18wt% sodium benzoate solution, carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 1.2MHz, and the power is 100W/L according to the volume of the solution; then, after one filtration, the mixture is dried for 12 hours at the temperature of 120 ℃.

(5) And (3) respectively adding 1.8g of the Beta molecular sieve obtained in the step (4) and 1g of ferric nitrate into 30mL of water, uniformly stirring, and carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 1.2MHz, and the power is 100W/L according to the volume of the solution.

(7) And (4) treating the solid substance obtained in the step (6) at 7900 ℃ for 2 h.

(8) And (3) mixing the substance obtained in the step (7) with 5mL of 55wt% NaOH solution, loading the mixture into a closed reactor, treating the mixture for 2h at 180 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃ to obtain macroporous iron oxide, wherein the number of the macroporous iron oxide is CL 2.

Example 3

(1) 0.88 g of sodium hydroxide was dissolved in 40 mL of 25wt% TEAOH and 10mL of distilled water, and stirred for 30 min. Then, 1.2 g of sodium aluminate was added thereto, and stirred for 30 min. Then 12 g of white carbon black is slowly added and stirred for 30 min. Then the mixture is put into a closed reaction kettle and crystallized in an oven for 50 hours at the temperature of 105 ℃. Then washing the obtained product to be neutral by using distilled water, and then drying the product for 12h at the temperature of 120 ℃ to obtain the Beta molecular sieve.

(2) And (2) putting the Beta molecular sieve obtained in the step (1) into 25mL of 10wt% propylene glycol solution, naturally settling, taking out 1/7 part solution in the middle of the whole solution when the molecular sieve just settles to the bottom, filtering, and drying at 120 ℃ for 10 h.

(3) Mixing the Beta molecular sieve obtained in the step (2) with 5mL of 0.1moL/L hydrochloric acid, loading the mixture into a closed reactor, treating the mixture for 2h at 172 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃.

(4) Mixing the Beta molecular sieve obtained in the step (3) with 5mL of 10wt% sodium benzoate solution, carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 0.9MHz, and the power is 50W/L according to the volume of the solution; then, after one filtration, the mixture is dried for 12 hours at the temperature of 120 ℃.

(5) And (3) respectively adding 0.2g of the Beta molecular sieve obtained in the step (4) and 1g of ferric nitrate into 25mL of water, uniformly stirring, and carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 1.2MHz, and the power is 50W/L according to the volume of the solution.

(7) And (4) treating the solid substance obtained in the step (6) at the constant temperature of 580 ℃ for 4 h.

(8) And (3) mixing the substance obtained in the step (7) with 5mL of 15wt% NaOH solution, loading the mixture into a closed reactor, treating the mixture for 8h at 120 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃ to obtain macroporous iron oxide, wherein the number of the macroporous iron oxide is CL 3.

Example 4

(1) 0.4 g of sodium hydroxide was dissolved in 25mL of 25wt% TEAOH and 15mL of distilled water, and stirred for 30 min. Then, 0.7g of sodium aluminate was added thereto, and stirred for 30 min. Then 12 g of white carbon black is slowly added and stirred for 30 min. Then the mixture is put into a closed reaction kettle and crystallized in an oven for 35 hours at the temperature of 120 ℃. Then washing the obtained product to be neutral by using distilled water, and then drying the product for 12h at the temperature of 120 ℃ to obtain the Beta molecular sieve.

(2) And (2) putting the Beta molecular sieve obtained in the step (1) into 45 mL of 70wt% propylene glycol solution, naturally settling the Beta molecular sieve, taking out 1/4 part of the solution in the middle of the whole solution when the molecular sieve just settles to the bottom, filtering, and drying at 120 ℃ for 10 h.

(3) Mixing the Beta molecular sieve obtained in the step (2) with 10mL0.5 moL/L hydrochloric acid, loading into a closed reactor, treating for 4h at 100 ℃, washing the obtained product with distilled water to neutrality, and drying for 12h at 120 ℃.

(4) Mixing the Beta molecular sieve obtained in the step (3) with 8mL of 15wt% sodium benzoate solution, carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 1.3MHz, and the power is 36W/L according to the volume of the solution; then, after one filtration, the mixture is dried for 12 hours at the temperature of 120 ℃.

(5) And (3) respectively adding 1g of the Beta molecular sieve obtained in the step (4) and 1g of ferric nitrate into 20mL of water, uniformly stirring, and carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 1.15MHz, and the power is 36W/L according to the volume of the solution.

(7) And (4) treating the solid substance obtained in the step (6) at the constant temperature of 580 ℃ for 5 hours.

(8) And (3) mixing the substance obtained in the step (7) with 8mL of 55wt% NaOH solution, loading the mixture into a closed reactor, treating the mixture for 7h at 150 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃ to obtain macroporous iron oxide, wherein the number of the macroporous iron oxide is CL 4.

Example 5

(1) 7g of commercial Beta molecular sieve (southern Kai university catalyst works) was placed in 50 mL of 50wt% propylene glycol solution and allowed to settle naturally, and when the molecular sieve just settled to the bottom, 1/3 part of the solution in the middle of the whole solution was taken out, filtered, and dried at 120 ℃ for 10 hours.

(2) Mixing the Beta molecular sieve obtained in the step (1) with 13mL of 15wt% sodium benzoate solution, and carrying out ultrasonic treatment for 20 min; then, after one filtration, the mixture is dried for 12 hours at the temperature of 120 ℃.

(3) Mixing the Beta molecular sieve obtained in the step (2) with 13mL moL/L hydrochloric acid, loading the mixture into a closed reactor, treating the mixture for 6h at 110 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃.

(4) And (3) respectively adding 0.7g of the Beta molecular sieve obtained in the step (3) and 0.58g of ferric nitrate into 15mL of water, uniformly stirring, and carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 0.95MHz, and the power is 32W/L according to the volume of the solution.

(5) Drying the obtained substance of step (4) at 120 ℃ until the water is completely evaporated.

(6) And (4) carrying out constant temperature treatment on the solid substance obtained in the step (5) at 500 ℃ for 2.5 h.

(7) And (3) mixing the substance obtained in the step (6) with 3.5mL of 40wt% NaOH solution, loading the mixture into a closed reactor, treating the mixture for 7h at 150 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃ to obtain macroporous iron oxide, wherein the number of the macroporous iron oxide is CL 5.

Example 6

(4) And (3) respectively adding 1.8g of the Beta molecular sieve obtained in the step (3) and 1g of ferric nitrate into 30mL of water, uniformly stirring, and carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 1.2MHz, and the power is 100W/L according to the volume of the solution.

(6) And (4) treating the solid substance obtained in the step (5) at the constant temperature of 900 ℃ for 2 h.

(7) And (3) mixing the substance obtained in the step (6) with 5mL of 55wt% NaOH solution, loading the mixture into a closed reactor, treating the mixture for 2h at 180 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃ to obtain macroporous iron oxide, wherein the serial number of the macroporous iron oxide is CL 6.

Example 7

(2) Mixing the Beta molecular sieve obtained in the step (1) with 15mL of hydrochloric acid with the concentration of 1moL/L, loading the mixture into a closed reactor, treating the mixture for 7 hours at the temperature of 60 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12 hours at the temperature of 120 ℃.

(3) Mixing the Beta molecular sieve obtained in the step (2) with 5mL of 18wt% sodium benzoate solution, carrying out ultrasonic treatment for 20min, wherein the frequency of ultrasonic waves is 1.2MHz, and the power is 100W/L according to the volume of the solution; then, after one filtration, the mixture is dried for 12 hours at the temperature of 120 ℃.

(7) And (3) mixing the substance obtained in the step (6) with 5mL of 55wt% NaOH solution, loading the mixture into a closed reactor, treating the mixture for 2h at 180 ℃, washing the obtained product to be neutral by using distilled water, and drying the product for 12h at 120 ℃ to obtain macroporous iron oxide, wherein the serial number of the macroporous iron oxide is CL 7.

Comparative example 1

Adding 1g of ferric nitrate into 20mL of water, uniformly stirring, and carrying out ultrasonic treatment, wherein the frequency of ultrasonic waves is 0.01MHz, and the power is 20W/L according to the volume of the solution; drying at 120 deg.C until water is completely evaporated; then processing for 5 hours at the constant temperature of 500 ℃; then mixing with 5mL of 40wt% NaOH solution, loading into a closed reactor, treating at 150 ℃ for 7h, washing the obtained product with distilled water to neutrality, and drying at 120 ℃ for 12h to obtain iron oxide, wherein the number of the iron oxide is CL 8.

TABLE 1 physicochemical Properties of samples obtained in examples and comparative examples

The concentration ratio of macropores is the proportion of macropores in plus or minus 20% (0.8D-1.2D) of the most probable pore diameter of macropores in the total macropores. The results of the examples and the comparative examples show that the method can prepare high-quality macroporous iron oxide, does not adopt the operation steps of the invention, and the prepared iron oxide under the condition of the same material proportion is non-porous common iron oxide and does not contain a macroporous structure.

Claims

1. A synthesis method of macroporous iron oxide comprises the following steps:

2. The synthesis method according to claim 1, wherein step (1) is preceded by a pretreatment step (1A) of putting said Beta zeolite into a screening solution, allowing the Beta zeolite to settle naturally in the screening solution, dividing the screening solution into n equal segments when the zeolite settles to the bottom of the screening solution, where n is an odd number greater than 1, selecting different segments of zeolite as required when screening the zeolite, and filtering and drying the screened zeolite.

3. The synthesis method according to claim 1, wherein step (1) is preceded by a pretreatment step (1A) of putting said Beta zeolite into a screening solution, allowing the Beta zeolite to settle naturally in the screening solution, dividing the screening solution into n equal segments when the zeolite settles to the bottom of the screening solution, where n is an odd number greater than 1, selecting the zeolite in the central segment as required, and filtering and drying the screened zeolite.

4. The synthesis method according to claim 2 or 3, wherein the screening solution is any one of a propylene glycol aqueous solution and a glycerol aqueous solution, the concentration of the screening solution is 5-75 wt%, and the mass ratio of the screening solution to the Beta molecular sieve is 1-10: 1.

5. The synthesis method according to claim 4, wherein the screening solution is any one of a propylene glycol aqueous solution and a glycerol aqueous solution, and the concentration of the screening solution is 10-70 wt%; the mass ratio of the screening solution to the Beta molecular sieve is 2-8: 1.

6. The synthesis method according to claim 1, wherein in the step (1), the acid solution is any one of hydrochloric acid, nitric acid and sulfuric acid, the concentration of the acid solution is 0.1-1 mol/L, and the liquid-solid mass ratio of the acid solution to the Beta molecular sieve is 1-10: 1.

7. The synthesis method according to claim 1, wherein in the step (1), the acid solution is any one of hydrochloric acid, nitric acid and sulfuric acid, the concentration of the acid solution is 0.1-1 mol/L, and the liquid-solid mass ratio of the acid solution to the Beta molecular sieve is 2-8: 1.

8. The synthesis method according to claim 1, wherein the washing in step (1) is washing with distilled water; the drying condition in the step (1) is that the treatment is carried out for 5-15 h at the temperature of 100-150 ℃.

9. The synthesis method according to claim 1, wherein the washing in step (1) is washing with distilled water; the drying condition in the step (1) is that the treatment is carried out for 6-12 h at the temperature of 110-140 ℃.

10. The synthesis method according to claim 1, wherein the concentration of the sodium benzoate solution in the step (2) is 2-20 wt%, and the liquid-solid mass ratio of the sodium benzoate solution to the Beta molecular sieve is 1-10: 1.

11. The synthesis method according to claim 1, wherein the concentration of the sodium benzoate solution in the step (2) is 3-18 wt%; the liquid-solid mass ratio of the sodium benzoate solution to the Beta molecular sieve is 2-8: 1.

12. The synthesis method according to claim 1, wherein the drying condition in the step (2) is 100 to 150 ℃ for 5 to 15 hours.

13. The synthesis method according to claim 1, wherein the drying condition in the step (2) is treatment at 110-140 ℃ for 6-12 h.

14. The synthesis method according to claim 1, wherein the mass ratio of the Beta molecular sieve, the ferric nitrate and the water in the step (3) is 0.1-2: 1: 10 to 33.

15. The synthesis method according to claim 1, wherein the mass ratio of the Beta molecular sieve, the ferric nitrate and the water in the step (3) is 0.2-1.8: 1: 12 to 30.

16. The synthesis method according to claim 1, wherein the drying temperature in the step (4) is 100 to 150 ℃.

17. The synthesis method according to claim 1, wherein the high-temperature treatment temperature in the step (5) is 300-900 ℃ and the treatment time is 1-10 h.

18. The synthesis method according to claim 1, wherein the high-temperature treatment temperature in the step (5) is 400-800 ℃; the treatment time is 2-8 h.

19. The synthesis method according to claim 1, wherein the alkali liquor in the step (6) is one or more of sodium hydroxide solution, potassium hydroxide solution and lithium hydroxide solution, the concentration of the alkali liquor is 15-55 wt%, and the mass ratio of the alkali liquor to the solid phase material is 1-10: 1.

20. The synthesis method according to claim 1, wherein the alkali liquor in the step (6) is one or more of sodium hydroxide solution, potassium hydroxide solution and lithium hydroxide solution, the concentration of the alkali liquor is 20-50 wt%, and the mass ratio of the alkali liquor to the solid phase material is 2-8: 1.

21. The synthesis method according to claim 1, wherein the treatment temperature in the step (6) is 120-180 ℃; the treatment time is 2-8 h.

22. The synthesis method according to claim 1, wherein the washing in the step (6) is washing with distilled water; the drying condition in the step (5) is that the treatment is carried out for 5-15 h at the temperature of 100-150 ℃.

23. The synthesis method according to claim 1, wherein the washing in the step (6) is washing with distilled water; the drying condition in the step (5) is that the treatment is carried out for 6-12 h at the temperature of 110-140 ℃.

24. The synthesis according to claim 1, wherein the Beta molecular sieve is prepared by: alkali source, silicon source, aluminum source, water and template agent TEAOH according to the molar ratio of 3-8 Na₂O：40～100SiO₂：A1₂O₃：800～1200H₂O: and (3) uniformly mixing 10-30 TEAOH, then placing the mixture into a closed reactor, crystallizing the mixture for 10-60 hours at the temperature of 100-180 ℃, and finally separating, washing and drying the crystallized product to obtain the Beta molecular sieve.

25. A synthesis process according to claim 24, wherein said source of alkalinity is sodium hydroxide; the aluminum source is one or more of sodium aluminate, aluminum sulfate, aluminum chloride and aluminum nitrate; the silicon source is white carbon black and/or silica sol; the templating agent is tetraethylammonium hydroxide.

26. The synthesis method according to claim 24, wherein the crystallization reaction temperature is 100-180 ℃ and the reaction time is 10-60 hours.

27. The synthesis method according to claim 24, wherein the crystallization reaction temperature is 105-160 ℃ and the reaction time is 20-50 h.

28. A synthesis process according to claim 24, wherein the washing is with distilled water; the drying condition is that the treatment is carried out for 5-15 hours at the temperature of 100-150 ℃.

29. A synthesis process according to claim 24, wherein the washing is with distilled water; the drying condition is that the treatment is carried out for 6-12 h at the temperature of 110-140 ℃.

30. A macroporous iron oxide obtained by the synthesis method of any one of claims 1 to 29, wherein the macroporous iron oxide has the following characteristics: the alpha-iron oxide is composed of macroporous channels, the pore diameter range of the macropores is 50-1400 nm, the most probable pore diameter D of the macropores is 60-900nm, and the proportion of the macropores in the range of 0.8D-1.2D in the whole macropores is more than 65%.

31. The macroporous iron oxide of claim 30, wherein the macroporous iron oxide has a specific surface area of 30 to 100m²/g。