Tin dioxide hollow structure material and preparation method and application thereof

Abstract

The invention relates to the technical field of materials and methane oxidative coupling, and discloses a stannic oxide hollow structure material and a preparation method and application thereof. The method provided by the invention is simple to operate, the ratio of the hollow structure in the obtained product is high, the production quality is stable, and the method is suitable for industrial large-scale production and application. The stannic oxide hollow structure material prepared by the method has an excellent methane oxidative coupling reaction catalytic effect, and can obtain higher C2 hydrocarbon selectivity.

Description

Technical Field

[0001] The invention relates to the fields of material technology and methane oxidative coupling technology, and in particular to a tin dioxide hollow structure material and a preparation method and application thereof. Background Art

[0002] SnO 2 As an n-type semiconductor material with a wide band gap of 3.6 eV, SnO has stable chemical properties and has been widely used in gas sensors, electrode materials, and other fields. 2 Since the surface has abundant oxygen vacancies and acidic sites, it can be used to catalyze reactions such as CO oxidation and methane oxidation.

[0003] SnO 2 SnO is a promising nanomaterial. It is not only rich in raw materials, non-toxic, and low in cost, but also can form a hollow structure material with a large specific surface area and excellent surface physical and chemical properties when it reaches the micrometer and nanometer scale. 2 Hollow structural materials have the characteristics of low density and high specific surface area, and their hollow parts can accommodate a large number of objects, which can produce some peculiar properties based on the microscopic "wrapping" effect, making them play an important role in technical fields such as medicine and chemical industry.

[0004] Currently prepared SnO 2 The main method for hollow structure materials is hydrothermal method or solvothermal method, that is, adding raw materials such as stannous salt, water, organic solvent and surfactant into a hydrothermal reactor for heating reaction. 2 The specific surface area of ​​the hollow structure material is still small, and the products with hollow structure account for a small proportion of the obtained products, resulting in SnO 2 Problems such as relatively low yield of hollow structure materials. Summary of the invention

[0005] The purpose of the present invention is to overcome the existing technology of preparing SnO 2 The preparation method of hollow structure material has low yield, complex operating conditions, and the obtained SnO 2 The specific surface area of ​​hollow structure materials needs to be improved, and the present invention provides a tin dioxide hollow structure material and a preparation method and application thereof. 2 The preparation of hollow structure materials is not only simple to operate, but also the proportion of hollow structures in the obtained products is high and the production quality is more stable.

[0006] In order to achieve the above object, the present invention first provides a SnO 2 Hollow structure material, the SnO 2The specific surface area of ​​hollow structural materials shall not be less than 80m 2 / g.

[0007] The second aspect of the present invention provides a method for preparing SnO 2 The method for preparing a hollow structural material comprises mixing a tin source, a halogen acid salt and a surfactant, and then performing ultrasonic treatment.

[0008] The third aspect of the present invention provides SnO prepared according to the method of the second aspect. 2 Hollow structural material.

[0009] The fourth aspect of the present invention provides the SnO 2 Hollow structure material, or, application of the method described in the second aspect in methane oxidative coupling reaction, especially application in preparing carbon dihydrocarbons by methane oxidative coupling.

[0010] The fifth aspect of the present invention provides a method for preparing carbon dihydrocarbons, the method comprising reacting a raw gas with the SnO2 described in the first aspect or the third aspect under methane oxidative coupling reaction conditions; 2 The hollow structure material is contacted, and the raw gas includes CH 4 and O 2 .

[0011] Through the above technical solution, the present invention can at least achieve the following beneficial effects:

[0012] (1) SnO provided by the present invention 2 The hollow structure material has a larger specific surface area and has a good catalytic effect when directly used in the methane oxidative coupling reaction, and can obtain higher carbon dihydrocarbon selectivity and yield.

[0013] (2) SnO provided by the present invention 2 The preparation method of the hollow structural material is simple, easy to operate, and the raw materials are readily available, so it is suitable for large-scale industrial promotion and application.

[0014] (3) SnO provided by the present invention 2 The preparation method of hollow structure materials has stable quality, and the proportion of hollow structure materials in the obtained products is relatively high, which improves the SnO 2 Yield and production efficiency of hollow structural materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The SnO obtained in Example 1 2 Scanning electron microscope image of the hollow structure material (the scale bar in the figure is 500nm). DETAILED DESCRIPTION

[0016] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0017] The inventor of the present invention accidentally discovered in the research that after treating the mixed system of stannous salt and surfactants by ultrasonic treatment, a SnO 2 The obtained SnO 2 Hollow structure materials have a larger specific surface area and relatively more active sites.

[0018] Based on the above findings, the present invention provides a SnO 2 Hollow structure material, the SnO 2 The specific surface area of ​​hollow structural materials shall not be less than 80m 2 / g.

[0019] According to a preferred embodiment of the present invention, wherein the SnO 2 The specific surface area of ​​hollow structural materials shall not be less than 85m 2 / g.

[0020] According to a preferred embodiment of the present invention, wherein the SnO 2 The pore diameter of the hollow structural material is 0.3-1 μm.

[0021] The second aspect of the present invention provides a method for preparing SnO 2 The method for preparing a hollow structural material comprises mixing a tin source, a halogen acid salt and a surfactant, and then performing ultrasonic treatment.

[0022] According to a preferred embodiment of the present invention, wherein, wherein, the tin source is selected from stannous salts, more preferably stannous chloride and / or stannous sulfate.

[0023] According to a preferred embodiment of the present invention, the halogen acid salt is selected from at least one of chlorate, bromate, hypochlorite and hypobromite.

[0024] Preferably, the halogen acid salt is at least one of sodium chlorate (NaClO3), potassium chlorate (KClO3), sodium hypochlorite (NaClO), potassium hypochlorite (KClO), sodium bromate (NaBrO3), potassium bromate (KBrO3), sodium hypobromite (NaBrO) and potassium hypobromite (KBrO).

[0025] According to a preferred embodiment of the present invention, the surfactant is selected from sodium dodecyl sulfate (SDS) and / or sodium octyl sulfonate (SOS).

[0026] According to a preferred embodiment of the present invention, wherein, wherein, the tin source (in the form of Sn 2+ The molar ratio of the halogenated salt (in terms of ions) to the halogenated salt is 1:0.1-0.5. For example, it can be 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, or any intermediate ratio within the range of any two of the above ratios.

[0027] According to a preferred embodiment of the present invention, the tin source (in the form of Sn 2+ The molar ratio of the surfactant (in terms of ions) to the surfactant is 1:0.5-2. For example, it can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, or any intermediate ratio within the range of any two of the above ratios.

[0028] Preferably, the tin source, halogen acid salt and surfactant are mixed in an aqueous solution system. For example, the tin source, halogen acid salt and surfactant having the above characteristics can be added to water to prepare a mixed solution (and then the mixed solution is subjected to ultrasonic treatment).

[0029] More preferably, in the aqueous solution system, the concentration of the tin source is 1-3% by weight, preferably 1-2% by weight, for example, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2% by weight, or any intermediate value in the range of any two of the above values.

[0030] More preferably, in the aqueous solution system, the concentration of the halogen acid salt is 0.01-1% by weight, preferably 0.05-0.5% by weight, for example, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5% by weight, or any intermediate value in the range of any two of the above values.

[0031] More preferably, the concentration of the surfactant in the aqueous solution is 1-10% by weight, preferably 1-5% by weight, for example, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, 3% by weight, 3.5% by weight, 4% by weight, 4.5% by weight, 5% by weight, or any intermediate value in the range consisting of any two of the above values.

[0032] According to a preferred embodiment of the present invention, the conditions for the ultrasonic treatment include: temperature 10-50°C; ultrasonic frequency 10-100KHz, and ultrasonic time 6-20h.

[0033] Preferably, the temperature of the ultrasonic treatment is 15-50° C. For example, it can be 15° C., 18° C., 20° C., 22° C., 25° C., 28° C., 30° C., 32° C., 35° C., 38° C., 40° C., 42° C., 45° C., 48° C., 50° C., or any intermediate value in the range formed by any two of the above values.

[0034] The third aspect of the present invention provides SnO prepared according to the method of the second aspect. 2 Hollow structural material.

[0035] The fourth aspect of the present invention provides the SnO 2 Hollow structure material, or, application of the method described in the second aspect in methane oxidative coupling reaction, especially application in preparing carbon dihydrocarbons by methane oxidative coupling.

[0036] In the present invention, the above application not only includes using the SnO 2 The hollow structure material is used as a catalyst (or a part of a catalyst, such as a catalyst carrier, etc.) in the methane oxidative coupling reaction. The hollow structure material can also be used in the industrial production of methane oxidative coupling, especially in the industrial production of carbon dihydrocarbon preparation by methane oxidative coupling reaction. The method provided by the present invention is used to prepare SnO 2 Hollow structure material preparation, and then use the SnO 2 Application solutions such as an overall production method of using hollow structural materials as a catalyst (or part of a catalyst) for methane oxidative coupling reaction.

[0037] The fifth aspect of the present invention provides a method for preparing carbon dihydrocarbons, the method comprising reacting a raw gas with the SnO2 described in the first aspect or the third aspect under methane oxidative coupling reaction conditions; 2 The hollow structure material is contacted, and the raw gas includes CH 4 and O 2 .

[0038] In order to obtain higher selectivity and yield of C2 hydrocarbons, according to a preferred embodiment of the present invention, in the feed gas, CH 4 and O 2 The volume ratio (also known as the "alkoxy ratio") is 5-12:1.

[0039] Preferably, the methane oxidative coupling reaction conditions include: a reaction temperature of 700-800°C, CH 4 and O 2 The raw material gas space velocity is 15000-25000mL / (g·h). “mL / (g·h)” refers to the raw material gas (CH 4 +O 2 )'s total volume (mL).

[0040] The present invention will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0041] In the following examples, unless otherwise specified, all reagents used were commercial products purchased from regular chemical suppliers and were of analytical grade.

[0042] Preparation Example 1

[0043] The following method was used to prepare SnO 2 Preparation of materials:

[0044] (1) Add 0.91 g of stannous chloride and 1.15 g of SDS to 50 g of water, stir for 10 min, and mix to form solution A.

[0045] (2) Add 0.05 g of sodium chlorate to solution A and mix well to obtain solvent B.

[0046] (3) Solvent B is subjected to ultrasonic treatment. The specific conditions include: frequency 40 kHz, temperature 25° C., and time 8 h.

[0047] (4) Filter the solid matter in the reaction system after ultrasonic treatment, then wash it with ethanol and dry it to obtain SnO 2 Material A1.

[0048] The SnO 2 Material A1, the SEM image obtained is as follows Figure 1 As shown in the figure, it can be seen that the SnO 2 The material exhibits obvious hollow structural characteristics. The BET method was used to characterize the SnO 2 The specific surface area of ​​material A1 was tested and the results showed that its specific surface area was 87.1 m2 / g.

[0049] Preparation Example 2

[0050] The following method was used to prepare SnO 2 Preparation of materials:

[0051] (1) Add 0.91 g of stannous chloride and 0.60 g of SDS to 50 g of water, stir for 10 min to dissolve and mix, and mix to form solution A.

[0052] (2) Add 0.11 g of sodium chlorate to solution A, dissolve and mix well to obtain solvent B.

[0053] (3) Solvent B is subjected to ultrasonic treatment. The specific conditions include: frequency 20 kHz, temperature 40° C., and time 10 h.

[0054] (4) Filter the solid matter in the reaction system after ultrasonic treatment, then wash it with ethanol and dry it to obtain SnO 2 Material A2. Its SEM image shows the same characteristics as Figure 1 Similar to the above, it shows obvious hollow structure characteristics. The BET method is used to detect SnO 2 The specific surface area of ​​material A2 is 86.6 m 2 / g.

[0055] Preparation Example 3

[0056] The following method was used to prepare SnO 2 Preparation of materials:

[0057] (1) Add 0.91 g of stannous chloride and 2.20 g of SDS to 50 g of water, stir for 10 min to dissolve and mix, and mix to form solution A.

[0058] (2) Add 0.15 g of sodium chlorate to solution A, dissolve and mix well to obtain solvent B.

[0059] (3) Solvent B is subjected to ultrasonic treatment. The specific conditions include: frequency 80 kHz, temperature 15° C., and time 6 h.

[0060] (4) Filter the solid matter in the reaction system after ultrasonic treatment, then wash it with ethanol and dry it to obtain SnO 2 Material A3. Its SEM image shows the same characteristics as Figure 1 Similar to the above, it shows obvious hollow structure characteristics. The BET method is used to detect SnO 2 The specific surface area of ​​material A3 is 85.2 m 2 / g.

[0061] Preparation Example 4

[0062] The following method was used to prepare SnO 2 Preparation of materials:

[0063] (1) Add 0.91 g of stannous chloride and 1.80 g of SDS to 50 g of water, stir for 10 min to dissolve and mix, and mix to form solution A.

[0064] (2) Add 0.22 g of sodium chlorate to solution A, dissolve and mix well to obtain solvent B.

[0065] (3) Solvent B is subjected to ultrasonic treatment. The specific conditions include: frequency 50 kHz, temperature 45° C., and time 18 h.

[0066] (4) Filter the solid matter in the reaction system after ultrasonic treatment, then wash it with ethanol and dry it to obtain SnO 2 Material A4. Its SEM image shows the same characteristics as Figure 1 Similar to the above, it shows obvious hollow structure characteristics. The BET method is used to detect SnO 2 The specific surface area of ​​material A4 is 85.7 m 2 / g.

[0067] Preparation Example 5

[0068] According to the method of Preparation Example 1, SnO 2 The difference in the preparation of the material is that the amount of SDS used is adjusted to 4g and the amount of potassium chlorate used is adjusted to 1g. Finally, SnO 2 Material A5. Its SEM image shows SnO 2 Material A5 presents a clear granular morphology, in which there is basically no hollow structure. The BET method is used to detect SnO 2 The specific surface area of ​​material A5 is only 43m 2 / g.

[0069] Preparation Example 6

[0070] According to the method of Preparation Example 1, SnO 2 The material was prepared in 50 g of water according to the raw materials listed in Table 1. The remaining operations and conditions were the same as those in Example 1. The specific surface area of ​​the obtained material was measured by the BET method, and the results are shown in Table 1.

[0071] Table 1

[0072]

[0073] The above materials were observed by transmission electron microscopy and it was found that materials A6-A8 all contained hollow SnO 2 The material, its SEM image shows the characteristics of Figure 1 similar.

[0074] Preparation Example 7

[0075] The method in Example 1 was used to prepare SnO 2 The material was prepared by ultrasonic treatment according to the conditions in Table 2. The remaining operations and conditions were the same as those in Example 1. The specific surface area of ​​the obtained material was measured by BET method, and the results are shown in Table 2.

[0076] Table 2

[0077] Material No. Frequency / kHz Temperature / ℃ Time / h <![CDATA[Specific surface area / m 2 ·g -1 > A9 100 25 8 84.9 A10 150 25 8 68.1 A11 40 25 30 70.8 A12 40 25 1 75.6 A13 40 50 8 85 A14 40 80 8 72.3 A15 40 10 8 82.4

[0078] The above materials were observed by transmission electron microscopy and it was found that A9, A13 and A15 were all SnO 2 The material, its SEM image shows the characteristics of Figure 1 Similarly, materials A10, A11, A12 and A14 contain SnO 2 Hollow structure and SnO without hollow structure 2 Particles.

[0079] Comparative Preparation Example 1

[0080] According to the method of Preparation Example 1, SnO 2 The difference is that in step (2), no ultrasonic treatment is performed, and solution B is only stirred at 25°C for 8 h. 2 Material D1, after testing, is basically in a granular form, containing only a very small amount of SnO with a hollow structure. 2 .

[0081] Comparative Preparation Example 2

[0082] Solvothermal method was used to prepare SnO 2 The material was prepared by the following method: 0.91 g of stannous chloride, 1.15 g of SDS, and 0.05 g of sodium chlorate were added into 50 g of water, mixed evenly, added into a reactor, and reacted at 120 °C for 18 h to obtain SnO 2 Material D2. After testing, D2 is SnO containing a hollow structure. 2 The material has a specific surface area of ​​72m 2 / g.

[0083] Test Example 1

[0084] The SnO prepared in the above examples and comparative examples was detected by scanning electron microscopy. 2 Content of hollow structures in materials. Three fields of view (the area of ​​a single field of view is about 4 μm × 4 μm) were selected for each material for statistics, and the content of hollow structures was calculated according to the following formula. The results are shown in Table 3.

[0085] Hollow structure content = SnO in the field of view 2 Number of hollow structures / all SnO in the field of view 2 Number of structures

[0086] Table 3

[0087] Material No. Hollow structure content / % Material No. Hollow structure content / % A1 95 A10 72 A2 92 A11 78 A3 91 A12 76 A4 93 A13 91 A5 15 A14 79 A6 92 A15 90 A7 93 D1 8 A8 91 D2 81 A9 90 / /

[0088] Test Example 2

[0089] The SnO 2 Preparation of materials: 5 batches of SnO were prepared continuously by each method. 2 Materials, respectively test each batch of SnO 2 The specific surface area and hollow structure content of the material are shown in Table 4.

[0090] Table 4

[0091]

[0092] Application Example 1

[0093] The SnO obtained in the above preparation example 2 The material was used as a catalyst, and a continuous flow fixed bed was used for methane oxidative coupling reaction. The reactor was a quartz tube with an inner diameter of 8 mm and a length of 530 mm. The catalyst loading was 0.6 g, and the reaction pressure was the pressure generated by the raw gas itself. The specific reaction conditions and results are shown in Table 5.

[0094] The reaction product components were analyzed and detected online using a gas chromatograph (purchased from Agilent, model 7890A). The products were determined using a dual detection channel three-valve four-column system, in which the FID detector was connected to an alumina column to analyze CH 4 , C 2 H 6 , C 2 H 4 , C 3 H 8 , C 3 H 6 , C 4 H 10 , C 4 H 8 , C n H m The TCD detector is mainly used to detect CO, CO 2 、N 2 , O 2 , CH 4 According to the test results, the methane conversion rate and C2 hydrocarbon selectivity (C2 selectivity), C2 hydrocarbon yield (C 2 yield), CO and CO 2 Overall selectivity (CO x Optional)

[0095] Methane conversion rate = molar amount of methane consumed in the reaction / initial molar amount of methane × 100%.

[0096] Ethylene selectivity = molar amount of methane consumed by the generated ethylene / total molar amount of methane consumed × 100% Ethane selectivity = molar amount of methane consumed by the generated ethane / total molar amount of methane consumed × 100% C 2 Selectivity = ethane selectivity + ethylene selectivity

[0097] C 2 Yield = methane conversion × (ethane selectivity + ethylene selectivity) × 100%

[0098] Table 5

[0099]

[0100] Note: In Table 5, the catalyst is the SnO obtained in the preparation examples and the comparative examples. 2 Materials: A1-1 to A1-5 are five batches of catalyst SnO prepared according to the method of Preparation Example 1 in Test Example 2 2 The number after “-” is the batch number of the material; the alkoxy ratio is the CH 4 and O 2 The volume ratio of CH 4 and O 2 The space velocity of the reaction raw gas; C 2 The yield is the yield after 1 h of reaction.

[0101] From the results in Table 5, it can be seen that the SnO 2 The material has good catalytic activity for methane oxidative coupling reaction. By using the material as a catalyst, a higher selectivity and yield of carbon dihydrocarbons can be obtained under high reaction temperature and high space velocity conditions. Moreover, the material has stable catalytic activity for a long time, which can improve the operation cycle of methane oxidative coupling reaction and has the potential for industrial application. Moreover, the test results of multiple batches of materials A1-1 to A1-5 show that the SnO prepared by the method provided by the present invention is 2 The material has high batch-to-batch stability, and the performance effects of products from different batches are very similar, which can meet the requirements of stable quality in industrial production.

[0102] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A SnO2 hollow structure material, characterized in that: The specific surface area of ​​the SnO2 hollow structure material is not less than 80m 2 / g.

2. The SnO2 hollow structure material according to claim 1, wherein: The specific surface area of ​​the SnO2 hollow structure material is not less than 85m 2 / g; And / or, the pore diameter of the SnO2 hollow structure material is 0.3-1 μm.

3. A method for preparing a SnO2 hollow structure material, characterized in that: The method comprises the steps of mixing a tin source, a halogen acid salt and a surfactant, and then performing ultrasonic treatment.

4. The method according to claim 3, wherein: The tin source is selected from stannous salts, preferably stannous chloride and / or stannous sulfate; and / or, the halogen acid salt is selected from at least one of chlorate, bromate, hypochlorite and hypobromite, preferably at least one of sodium chlorate, potassium chlorate, sodium hypochlorite, potassium hypochlorite, sodium bromate, potassium bromate, sodium hypobromite and potassium hypobromite; And / or, the surfactant is selected from sodium dodecyl sulfate and / or sodium octyl sulfonate.

5. The method according to claim 3 or 4, wherein: The molar ratio of the tin source to the halogen acid salt is 1:0.1-0.5; And / or, the molar ratio of the tin source to the surfactant is 1:0.5-2.

6. The method according to claim 3, wherein: The ultrasonic treatment conditions include: temperature 10-50°C; ultrasonic frequency 10-100kHz; and ultrasonic time 6-20h.

7. The SnO2 hollow structure material prepared according to the method according to any one of claims 3 to 6.

8. The SnO2 hollow structure material according to claim 1, 2 or 7, or the method according to any one of claims 3 to 6, used in the oxidative coupling reaction of methane, especially in the preparation of carbon dihydrocarbons by oxidative coupling of methane.

9. A method for preparing carbon dihydrocarbons, characterized in that: The method comprises contacting a raw gas with the SnO2 hollow structure material according to claim 1, 2 or 7 under methane oxidative coupling reaction conditions, wherein the raw gas comprises CH4 and O2.

10. The method according to claim 9, wherein: In the raw gas, the volume ratio of CH4 to O2 is 5-12:1; Preferably, the methane oxidative coupling reaction conditions include: a reaction temperature of 700-800°C; and a raw gas space velocity of 15000-25000 mL / (g·h) based on CH4 and O2.

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