Catalyst for benzene complete oxidation reaction, preparation method thereof and benzene complete oxidation reaction method

Abstract

The invention relates to the technical field of molecular sieve preparation, and provides a preparation method of a catalyst for a benzene complete oxidation reaction. The preparation method comprises the following steps: mixing SBA molecular sieve raw powder, a metal source, a first silicon source and an alkali solution to obtain a mixture, and molding and drying the mixture to obtain a molecular sieve A; wherein the metal source comprises at least one of a gold source, a platinum source and a palladium source; mixing an organic template agent R, water, a second silicon source and acid to obtain a solution B; and adding the solution B into the molecular sieve A, carrying out hydrothermal crystallization, filtering, washing, drying and roasting to obtain the catalyst for the complete oxidation reaction of benzene. The preparation method provided by the invention is simple, and the prepared catalyst is covered with the silicon dioxide film outside the molecular sieve, so that metal active sites are not easy to lose in the reaction process. The invention also provides a catalyst for benzene complete oxidation reaction and a benzene complete oxidation reaction method.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieve preparation, and more specifically to a catalyst for benzene complete oxidation reaction and a preparation method thereof, as well as a benzene complete oxidation reaction method. Background Art

[0002] SBA-15 and SBA-16 are both typical mesoporous molecular sieves, which have the characteristics of large specific surface area, adjustable pore size and good hydrothermal stability. They can not only increase the contact between catalyst and reactant and promote the reaction, but also have higher mass transfer and heat transfer performance. Therefore, they are often used as catalyst carriers for the preparation of noble metal (Pt, Rh, Pd, Au, etc.) supported catalysts. These noble metal supported catalysts are not only commonly used in hydrogenation and dehydrogenation reactions as heterogeneous catalysts, but also can be used in selective reduction, small molecule gas (CO, methane, etc.) and volatile organic compounds (VOCs) complete oxidation reactions. Such as hydrogenation reaction of benzene, toluene, cyclohexene, dehydrogenation reaction of propane, selective catalytic reduction reaction (SCR) of NOx, oxidation reaction of CO, combustion reaction of methane, complete oxidation and decomposition reaction of typical VOCs such as benzene, toluene and n-hexane, and even oxidation reaction of some polycyclic aromatic hydrocarbons.

[0003] The catalyst preparation method has a great influence on the properties of precious metal supported catalysts. Since precious metals are expensive, their dosage is usually reduced as much as possible during the catalyst preparation process, while maintaining the stability of the catalyst and extending the service life of the catalyst as much as possible, thereby achieving the purpose of reducing the cost of the catalyst. One of the strategies for catalyst preparation is usually to achieve nano-high dispersion of precious metals on the carrier surface during the preparation process as much as possible, thereby enhancing the catalytic efficiency of precious metals, while reducing the loss of precious metals during the reaction process, thereby extending the service life of the catalyst. However, the metal components in the existing supported catalysts are dispersed on the surface of the molecular sieve, resulting in the loss of metal components very easily during the reaction process. Therefore, there are technical problems such as shortened catalyst service life and reduced catalytic effect. Summary of the invention

[0004] In order to solve the above technical problems, one of the purposes of the present invention is to provide a method for preparing a catalyst for the complete oxidation reaction of benzene. During the kneading process of the catalyst, a raw silicon source used for synthesizing molecular sieves is added, and then the silicon source is hydrolyzed into viscous silica gel to bond the catalyst. At the same time, the secondary pore distribution of the molecular sieve is improved in this process.

[0005] The present invention also aims to provide a catalyst for the complete oxidation of benzene and a method for the complete oxidation of benzene.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a method for preparing a catalyst for a complete oxidation reaction of benzene, comprising:

[0008] S1. Mixing SBA molecular sieve powder, a metal source, a first silicon source and an alkaline solution to obtain a mixture, and forming and drying the mixture to obtain a molecular sieve A; wherein the metal source comprises at least one of a gold source, a platinum source and a palladium source;

[0009] S2. The organic template R, water, a second silicon source and an acid are mixed to obtain a solution B;

[0010] S3. Add solution B to molecular sieve A, perform hydrothermal crystallization, filter, wash, dry and calcine to obtain a catalyst for complete oxidation of benzene.

[0011] The present invention provides a preparation method for a catalyst for a complete oxidation reaction of benzene, wherein a first silicon source is hydrolyzed under the action of an alkaline solution to generate a viscous silica mesh, and the viscous silica mesh bonds the molecular sieve particles to each other. After extrusion, the viscous silica mesh is transformed into a silicon dioxide film under the condition of high temperature roasting, and covers the silicon hydroxyl structure on the outer surface of the molecular sieve. Due to the silicon dioxide film and the molecular sieve's own skeleton structure silicon oxygen structure type, the outer surface of the molecular sieve is not covered and blocked, and in practical applications, the reactant enters the outer surface of the molecular sieve from the silicon dioxide film in the form of diffusion. However, since there is a metal distributed on the outer surface of the molecular sieve, the formed silicon dioxide film has a gap at the position of the metal, and hydrothermal crystallization is performed by adding a mixed solution of an organic template agent R, water, a second silicon source and an acid, and the position of the gap is crystallized and grown to form a complete silicon dioxide film on the outer surface of the molecular sieve. These silicon dioxide films can improve the mechanical strength of the molecular sieve and provide a protective film for the molecular sieve structure itself. Since this protective film is similar to the silicon dioxide structure of the molecular sieve skeleton structure, it will not affect the activity and diffusion performance of the molecular sieve itself, and it can also make the metal active sites difficult to lose during the reaction process, effectively extending the life and activity of the catalyst. In addition, the silicon dioxide film formed on the outer surface of the molecular sieve can also effectively avoid the problem of metal particles agglomerating at high temperatures and causing catalyst deactivation.

[0012] According to some embodiments of the present invention, the gold source includes one or more of gold oxide, hydroxide, sulfide, chloride, and cyanide; and / or the platinum source includes one or more of platinum oxide, hydroxide, sulfide, chloride, and cyanide; and / or the palladium source includes one or more of palladium oxide, hydroxide, sulfide, chloride, and cyanide.

[0013] According to some embodiments of the present invention, the SBA molecular sieve raw powder includes SBA-15 molecular sieve raw powder or SBA-16 molecular sieve raw powder.

[0014] According to some embodiments of the present invention, the first silicon source includes at least one of tetraethyl orthosilicate (TEOS), silica sol, and water glass, preferably tetraethyl orthosilicate.

[0015] According to some embodiments of the invention, the base in the alkaline solution comprises NaOH.

[0016] According to some embodiments of the present invention, the organic template R includes at least one of an amphiphilic nonionic triblock surfactant and hexamethylenetetramine (HMTA).

[0017] According to some embodiments of the present invention, the amphiphilic nonionic triblock surfactant comprises F127 (EO 106 PO 70 EO 106 )、F108(EO 132 PO 50 EO 132 )、P123(EO 20 PO 70 EO 20 )、P104(EO 27 PO 61 EO 27 ) at least one of.

[0018] According to some embodiments of the present invention, when the SBA molecular sieve raw powder is SBA-15 molecular sieve raw powder, the organic template R is selected from one or more of P123 or P104; when the SBA molecular sieve raw powder is SBA-16 molecular sieve raw powder, the organic template R is selected from one or more of F127, F108 and HMTA.

[0019] According to some embodiments of the present invention, the second silicon source includes at least one of white carbon black, tetraethyl orthosilicate (TEOS), sodium silicate, and silica sol, preferably tetraethyl orthosilicate.

[0020] According to some embodiments of the present invention, the acid includes at least one of hydrochloric acid, sulfuric acid, and nitric acid, preferably hydrochloric acid.

[0021] According to some embodiments of the present invention, the mass ratio of the metal source to the SBA molecular sieve raw powder is 1 to 10:100.

[0022] According to some embodiments of the present invention, the mass ratio of the first silicon source to the SBA molecular sieve raw powder is 1:5-10.

[0023] According to some embodiments of the present invention, the alkali solution contains OH - The ratio of the molar amount of the base calculated as SiO2 to the molar amount of the first silicon source calculated as SiO2 is 0.5 to 4:1.

[0024] According to some embodiments of the present invention, the alkali solution contains OH - The ratio of the molar amount of the base calculated as SiO2 to the molar amount of the first silicon source calculated as SiO2 is 0.5 to 3.5:1.

[0025] According to some embodiments of the present invention, the molar ratio of the components in the solution B is SiO2:a H2O:b R:c H + , wherein the value of a is 80 to 200, preferably 100 to 160, the value of b is 0.005 to 0.030, preferably 0.010 to 0.025, and the value of c is 0.10 to 0.25, preferably 0.15 to 0.20.

[0026] According to some embodiments of the present invention, the mixture in step S1 is first dried, and then the dried mixture is mixed with water and molded.

[0027] According to some embodiments of the present invention, the mass of water mixed with the dried mixture is 10% to 30%, preferably 15% to 25% of the mass of the dried mixture.

[0028] According to some embodiments of the present invention, the drying temperature in step S1 is 100-140°C, preferably 110-130°C.

[0029] According to some embodiments of the present invention, the crystallization temperature in step S3 is 80 to 130° C., preferably 90 to 120° C.; the crystallization time is 24 to 90 hours, preferably 40 to 70 hours.

[0030] According to some embodiments of the present invention, the drying temperature in step S3 is 100-140°C, preferably 110-130°C.

[0031] According to some embodiments of the present invention, the calcination temperature in step S3 is 400-700° C., preferably 500-600° C.; and the calcination time is 5-8 hours.

[0032] In a second aspect, the present invention provides a catalyst for complete oxidation reaction of benzene, which is prepared by the preparation method described in the first aspect.

[0033] According to some embodiments of the present invention, the surface of the catalyst for the complete oxidation reaction of benzene includes a silica shell layer, and preferably, the particle diameter of the catalyst for the complete oxidation reaction of benzene is 30 to 50 nm.

[0034] In a third aspect, the present invention provides a method for complete oxidation of benzene, which is prepared by the preparation method described in the first aspect or catalyzed by the catalyst for complete oxidation of benzene described in the second aspect.

[0035] The beneficial effects of the present invention are at least:

[0036] The preparation method of the catalyst for the complete oxidation reaction of benzene provided by the present invention is simple, a metal source is directly added in the molecular sieve forming stage, the molecular sieve does not need to be impregnated with a metal solution, and the forming and metal impregnation processes are completed in one step; the prepared metal-loaded SBA molecular sieve is covered with a silicon dioxide film outside the molecular sieve, which provides a protective film for the structure of the molecular sieve itself, so that the metal active sites are not easy to be lost during the reaction process, and the life and activity of the catalyst are effectively extended. The catalyst is used in the complete oxidation reaction of benzene, and the benzene conversion rate can be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a scanning electron microscope image of the catalyst prepared in Example 3. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this patent in detail and do not limit the scope of protection of the present invention in any way.

[0039] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the reagent amounts, unless otherwise specified, are the reagent amounts used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods.

[0040] Among them, XPS uses Thermo's ESCALAB 250spectrometer X-ray photoelectron spectrometer to measure the bonding of metal particles.

[0041] The scanning electron microscope used was Hitachi S-4700 scanning electron microscope.

[0042] Example 1

[0043] S1. Add 40g SBA-16 molecular sieve powder, 0.8g Au2O, 4g tetraethyl orthosilicate (TEOS) and 0.3L 0.1mol / LNaOH solution into a mortar and mix. After mixing evenly, dry at 100°C. Then take 30g of the dried sample and put it into an extruder. Add 3g deionized water and stir evenly to start molding. The molded molecular sieve is dried at 100°C and recorded as molecular sieve A.

[0044] S2. 1.6 g F127 and 34.5 g deionized water were added to the reactor in sequence, stirred evenly, and then 24.1 mL 0.1 mol / L hydrochloric acid solution was added. Stirring was continued, and 5 g tetraethyl orthosilicate (TEOS) was slowly added dropwise to obtain solution B. The molar ratio of each component in solution B was SiO2: 80H2O: 0.005R: 0.1H + .

[0045] S3. After mixing solution B and molecular sieve A, transfer them to a crystallization kettle, raise the temperature to 90°C, and crystallize at a constant temperature for 40 hours. After the crystallization is complete, wait for the temperature to drop to room temperature, separate and wash the reaction mixture, dry it at 100°C, and finally calcine it at 400°C for 8 hours to obtain the catalyst sample.

[0046] Example 2

[0047] S1. Add 40g SBA-16 molecular sieve powder, 1.6g AuCl3, 6g silica sol (SW-25, silica content is 25wt%) and 0.3L 0.1mol / L NaOH solution into a mortar and mix them. After mixing evenly, dry them at 100°C. Then take 30g of the dried sample and put it into an extruder, add 6g deionized water, stir evenly and start molding. The molded molecular sieve is dried at 100°C and recorded as molecular sieve A.

[0048] S2. 4.4 g F108 and 54 g deionized water were added to the reactor in sequence, stirred evenly, and then 44.8 mL 0.1 mol / L sulfuric acid solution was added, stirring was continued, and 2 g white carbon black (silicon dioxide content was 90 wt%) was slowly added dropwise to obtain solution B. The molar ratio of each component in solution B was SiO2: 100H2O: 0.01R: 0.15H + .

[0049] S3. After mixing solution B and molecular sieve A, transfer them to a crystallization kettle, raise the temperature to 100°C, and crystallize at a constant temperature for 50 hours. After the crystallization is complete, wait for the temperature to drop to room temperature, separate and wash the reaction mixture, dry it at 110°C, and finally calcine it at 500°C for 6 hours to obtain the catalyst sample.

[0050] Example 3

[0051] S1. Add 40g SBA-16 molecular sieve powder, 3.2g AuCl3, 6g tetraethyl orthosilicate (TEOS) and 0.15L 0.1mol / L NaOH solution into a mortar and mix. After mixing evenly, dry at 100°C. Then take 30g of the dried sample and put it into an extruder. Add 7.5g deionized water and stir evenly to start molding. The molded molecular sieve is dried at 100°C and recorded as molecular sieve A.

[0052] S2. 0.15 g of hexamethylenetetramine (HMTA) and 82.5 g of deionized water were added to the reactor in sequence, stirred evenly, and then 83 mL of 0.1 mol / L nitric acid solution was added. Stirring was continued, and 10 g of silica sol (SW-25, with a silicon dioxide content of 25 wt%) was slowly added dropwise to obtain solution B. The molar ratio of each component in solution B was SiO2: 110H2O: 0.025R: 0.2H + .

[0053] S3. After mixing solution B and molecular sieve A, transfer them to a crystallization kettle, raise the temperature to 110°C, and crystallize at a constant temperature for 60 hours. After the crystallization is complete, wait for the temperature to drop to room temperature, separate and wash the reaction mixture, dry it at 120°C, and finally calcine it at 550°C for 7 hours to obtain the catalyst sample.

[0054] The scanning electron microscopy images of the obtained catalyst samples are shown in Figure 1 . Figure 1 It can be clearly seen that the outer surface of the catalyst sample is a silicon dioxide film (or silicon dioxide shell), and no metal oxide can be seen in the entire field of view, indicating that the metal oxide is distributed on the outer surface of the molecular sieve within the silicon dioxide film. Since the outer surface of the metal oxide is protected by the silicon dioxide film, the metal on the outer surface of the molecular sieve is not easily lost during the reaction, thereby extending the service life of the catalyst.

[0055] Example 4

[0056] S1. Add 40g SBA-15 molecular sieve powder, 3.2g PtO, 6g tetraethyl orthosilicate (TEOS) and 0.3L 0.1mol / L NaOH solution into a mortar and mix. After mixing evenly, dry and dry at 130°C. Then take 30g of the dried sample and put it into an extruder. Add 7.5g deionized water and stir evenly before forming. The formed molecular sieve is dried at 130°C and recorded as molecular sieve A.

[0057] S2. 4.2 g P104 and 38.9 g deionized water were added to the reactor in sequence, stirred evenly, and then 60 mL hydrochloric acid solution (0.1 mol / L) was added. Stirring was continued, and 5 g tetraethyl orthosilicate (TEOS) was slowly added dropwise to obtain solution B. The molar ratio of each component in solution B was SiO2: 90H2O: 0.03R: 0.25H + .

[0058] S3. After mixing solution B and molecular sieve A, transfer them to a crystallization kettle, raise the temperature to 130°C, and crystallize at a constant temperature for 90 hours. After the crystallization is complete, wait for the temperature to drop to room temperature, separate and wash the reaction mixture, dry it at 130°C, and finally calcine it at 400°C for 8 hours to obtain the catalyst sample.

[0059] Example 5

[0060] S1. Add 40g SBA-15 molecular sieve powder, 3.2g PdCl2, 6g tetraethyl orthosilicate (TEOS) and 0.3L 0.1mol / L NaOH solution into a mortar and mix. After mixing evenly, dry and dry at 130°C. Then take 30g of the dried sample and put it into an extruder. Add 7.5g deionized water and stir evenly before starting to shape it. Dry the formed molecular sieve at 120°C and record it as molecular sieve A.

[0061] S2. 4.2 g P104 and 38.9 g deionized water were added to the reactor in sequence, stirred evenly, and then 60 mL hydrochloric acid solution (0.1 mol / L) was added. Stirring was continued, and 5 g tetraethyl orthosilicate (TEOS) was slowly added dropwise to obtain solution B. The molar ratio of each component in solution B was SiO2: 90H2O: 0.03R: 0.25H + .

[0062] S3. After mixing solution B and molecular sieve A, transfer them to a crystallization kettle, raise the temperature to 130°C, and crystallize at a constant temperature for 90 hours. After the crystallization is complete, wait for the temperature to drop to room temperature, separate and wash the reaction mixture, dry it at 130°C, and finally calcine it at 400°C for 8 hours to obtain the molecular sieve sample.

[0063] Comparative Example 1

[0064] 40g SBA-15 molecular sieve powder and 14.2g pseudo-boehmite (Al2O3 content is 70wt%) are added to a mixer and mixed. After mixing evenly, 25.8g dilute nitric acid (HNO3 content is 6.3wt%) is added for kneading, and then 15.5g deionized water is added for further kneading. The kneaded material is then put into an extruder for molding. The molded molecular sieve is dried at 130°C and then calcined at 400°C for 8h. The calcined molecular sieve is then mixed with 3.2g AuCl3 for 4h, dried at 130°C and then calcined at 400°C for 8h to obtain an Au / SBA-15 catalyst sample.

[0065] Comparative Example 2

[0066] S1. Add 40g SBA-15 molecular sieve powder, 3.2g AuCl3, 6g tetraethyl orthosilicate (TEOS) and 2.1L 0.1mol / LNaOH solution into a mortar and mix. After mixing evenly, dry and dry at 130°C. Then take 30g of the dried sample and put it into an extruder. Add 7.5g deionized water and stir evenly before starting to shape it. The formed molecular sieve is dried at 130°C and recorded as molecular sieve A.

[0067] S2. 4.2 g P104 and 38.9 g deionized water were added to the reactor in sequence, stirred evenly, and then 60 mL hydrochloric acid solution (0.1 mol / L) was added. Stirring was continued, and 5 g tetraethyl orthosilicate (TEOS) was slowly added dropwise to obtain solution B. The molar ratio of each component in solution B was SiO2: 90H2O: 0.03R: 0.25H + .

[0068] S3. After mixing solution B and molecular sieve A, transfer them to a crystallization kettle, raise the temperature to 130°C, and crystallize at a constant temperature for 90 hours. After the crystallization is complete, wait for the temperature to drop to room temperature, separate and wash the reaction mixture, dry it at 130°C, and finally calcine it at 400°C for 8 hours to obtain the catalyst sample.

[0069] Catalytic effect evaluation

[0070] The catalyst samples prepared in the embodiments and comparative examples were used for the complete oxidation reaction of benzene, and the specific process was as follows:

[0071] The complete oxidation reaction of benzene was carried out in a fixed bed reactor. 63 mg of catalyst was loaded into a quartz reaction tube, and the upper and lower sides of the catalyst were sealed with quartz wool. A thermocouple on the outside of the reaction tube was used to control the temperature of the reactor, and another thermocouple was inserted into the inside of the quartz reaction tube to measure the temperature of the catalyst bed. Air (flow rate was 98 mL / min) and reaction gas were introduced into the two gas paths, and the reactant concentration was about 5.6 g / m3 (The temperature of the low temperature thermostat is controlled at 11°C, and the air flow rate is 2mL / min), and then enters the reactor after mixing. When the reactor bed temperature reaches 550°C, the activity of the catalyst is measured after being stable for about 20 minutes, and the concentration of benzene in the tail gas is detected by gas chromatograph. The test results are shown in Table 1.

[0072] Table 1

[0073] Benzene conversion rate (%) Example 1 90.5 Example 2 90.9 Example 3 91.6 Example 4 92.7 Comparative Example 1 43.9 Comparative Example 2 15.8

[0074] It can be seen from the above test results that the catalysts prepared by the preparation method provided by the present invention in Examples 1-4 showed excellent catalytic performance in the complete oxidation reaction of benzene.

[0075] Comparative Example 1 uses a traditional loading impregnation method. Firstly, due to the addition of adhesives during the molding process, the traditional method has relatively fewer active sites in the catalyst of the same mass. Secondly, due to the lack of protection of the outer surface silica film, the metals on the surface of these molecular sieves are very likely to be lost during the reaction, resulting in a decrease in catalyst activity.

[0076] In Comparative Example 2, due to the addition of too much alkali, the framework of the molecular sieve itself will collapse while the silicon source is hydrolyzed to form a silicon dioxide film and a sticky network, so the catalytic activity is very low.

[0077] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for preparing a catalyst for complete oxidation of benzene, characterized in that: The following steps are involved: S1. Mixing SBA molecular sieve powder, a metal source, a first silicon source and an alkaline solution to obtain a mixture, and forming and drying the mixture to obtain a molecular sieve A; wherein the metal source comprises at least one of a gold source, a platinum source and a palladium source; S2. The organic template R, water, a second silicon source and an acid are mixed to obtain a solution B; S3. Add solution B to molecular sieve A, perform hydrothermal crystallization, filter, wash, dry and calcine to obtain a catalyst for complete oxidation of benzene.

2. The preparation method according to claim 1, characterized in that: The gold source includes one or more of gold oxide, hydroxide, sulfide, chloride, and cyanide; and / or the platinum source includes one or more of platinum oxide, hydroxide, sulfide, chloride, and cyanide; and / or the palladium source includes one or more of palladium oxide, hydroxide, sulfide, chloride, and cyanide.

3. The preparation method according to claim 1 or 2, characterized in that: The SBA molecular sieve raw powder includes SBA-15 molecular sieve raw powder or SBA-16 molecular sieve raw powder; and / or, the first silicon source comprises at least one of tetraethyl orthosilicate, silica sol, and water glass, preferably tetraethyl orthosilicate; And / or, the alkali in the alkali solution comprises NaOH.

4. The preparation method according to any one of claims 1 to 3, characterized in that The organic template R comprises at least one of an amphiphilic nonionic triblock surfactant and hexamethylenetetramine; And / or, the second silicon source includes at least one of white carbon black, tetraethyl orthosilicate, sodium silicate, and silica sol; And / or, the acid includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The amphiphilic nonionic triblock surfactant includes at least one of F127, F108, P123, and P104; And / or, the second silicon source is tetraethyl orthosilicate; And / or, the acid is hydrochloric acid.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The mass ratio of the metal source to the SBA molecular sieve raw powder is 1 to 10:100; And / or, the mass ratio of the first silicon source to the SBA molecular sieve raw powder is 1:5-10; And / or, the alkaline solution contains OH - The ratio of the molar amount of the base calculated as SiO2 to the molar amount of the first silicon source calculated as SiO2 is 0.5 to 4:1, preferably 0.5 to 3.5:

1.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The molar ratio of each component in the solution B is SiO2:a H2O:b R:c H + , wherein the value of a is 80 to 200, preferably 100 to 160, the value of b is 0.005 to 0.030, preferably 0.010 to 0.025, and the value of c is 0.10 to 0.25, preferably 0.15 to 0.

20.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The mixture in step S1 is first dried, and then the dried mixture is mixed with water and then formed; Preferably, the mass of water mixed with the dried mixture is 10% to 30%, preferably 15% to 25% of the mass of the dried mixture.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The drying temperature in step S1 is 100-140°C, preferably 110-130°C; And / or, the crystallization temperature in step S3 is 80-130° C., preferably 90-120° C.; the crystallization time is 24-90 hours, preferably 40-70 hours; And / or, the drying temperature in step S3 is 100-140° C., preferably 110-130° C.; And / or, the calcination temperature in step S3 is 400-700° C., preferably 500-600° C.; and the calcination time is 5-8 hours.

10. A catalyst for complete oxidation reaction of benzene, prepared by the preparation method according to any one of claims 1 to 9, wherein the surface of the catalyst for complete oxidation reaction of benzene comprises a silica shell layer, and preferably the particle diameter of the catalyst is 30 to 50 nm.

11. A method for complete oxidation of benzene, wherein the reaction is catalyzed by the catalyst prepared by the preparation method according to any one of claims 1 to 9 or the catalyst according to claim 10.

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