Methods for preparing porous tin oxide materials by low-temperature pyrolysis, porous tin oxide materials and their applications
The preparation of porous tin oxide materials by low-temperature pyrolysis solves the problems of complex preparation and high cost in existing technologies, and achieves high-efficiency catalytic effect in methane oxidative coupling reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-08-11
- Publication Date
- 2026-07-31
AI Technical Summary
Existing porous tin oxide materials have complex preparation processes, high costs, and high energy consumption, making them difficult to apply effectively to methane oxidative coupling reactions.
Porous tin oxide materials were prepared by a low-temperature pyrolysis method. By mixing alkoxytin with a C1-C10 monohydric alcohol and calcining at 280-550℃, a SnO2 material with a porous structure was prepared for use in methane oxidative coupling reaction.
It simplifies the preparation process, reduces production costs, improves methane conversion and C2 hydrocarbon selectivity, reduces energy consumption, has high safety, and is suitable for methane oxidative coupling reactions.
Smart Images
Figure CN117658203B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of methane oxidative coupling technology, specifically to a method for preparing porous tin oxide materials by low-temperature pyrolysis, and the porous tin oxide materials and their applications. Background Technology
[0002] In recent years, materials with porous structures have received widespread attention and application, as their porous structure has enabled them to play a significant role in catalysis, electrodes, and separation materials. Especially in the field of catalysis, the porous structure not only allows small molecules in the reaction to enter the internal channels with low diffusion resistance, but also allows the internal active sites to fully function. Therefore, this type of material has attracted increasing attention in the field of catalysis.
[0003] Methane is a major component of natural gas, making its chemical utilization extremely important. The oxidative coupling of methane to ethylene (OCM) technology has significant academic value and potential economic potential.
[0004] SnO2 is a multifunctional material, exhibiting unique catalytic activity and selectivity, particularly in the field of catalysis. Its porous structure gives it a unique character, making it considered one of the most promising catalysts. SnO2 contains abundant metastable surface defect oxygen species, and its lattice oxygen can also be reduced. Therefore, there have been reports on using SnO2 catalysts for the oxidative coupling reaction of methane. However, these reports mainly focus on modifying tin oxide with auxiliary components. For example, Professor Wang Xiang's group at Nanchang University prepared a series of alkali metal-modified SnO2 catalysts for the oxidative coupling reaction of methane, demonstrating stable catalytic performance. Summary of the Invention
[0005] The purpose of this invention is to overcome the complexity of existing porous tin oxide material preparation processes and to provide a method for preparing porous tin oxide materials using a low-temperature pyrolysis method, as well as the porous tin oxide materials and their applications. This invention employs a low-temperature pyrolysis method to prepare porous tin oxide (SnO2) materials. This pyrolysis method features low temperature, good safety, low energy consumption, and is simple and easy to implement, facilitating large-scale promotion and use. The raw materials used in the experiment are simple, readily available, and pollution-free, and the resulting SnO2 with a porous structure exhibits excellent performance.
[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing porous tin oxide materials by low-temperature pyrolysis, the method comprising mixing alkoxytin with a C1-C10 monohydric alcohol and then calcining at 280-550°C.
[0007] A second aspect of the present invention provides a porous tin oxide material prepared by the method described above.
[0008] A third aspect of the present invention provides a method for methane oxidative coupling reaction, the method comprising: contacting a feed gas with the porous tin oxide material described above under methane oxidative coupling reaction conditions;
[0009] Alternatively, a porous tin oxide material can be prepared according to the method described above, and then the raw material gas can be contacted with the prepared porous tin oxide material under methane oxidative coupling reaction conditions.
[0010] Through the above technical solution, the present invention achieves the following beneficial technical effects:
[0011] This invention employs a one-step method to prepare porous tin oxide materials, simplifying the preparation process. The raw materials used in this invention are inexpensive and pollution-free, reducing the use of acids and alkalis, saving energy, and lowering production costs. The porous tin oxide materials prepared by this invention have a low preparation temperature and high safety, providing a foundation for the application of porous tin oxide materials as catalysts.
[0012] The porous tin oxide material of the present invention can improve methane conversion, C2 hydrocarbon selectivity, and C2 hydrocarbon yield when used in methane oxidative coupling reaction. Attached Figure Description
[0013] Figure 1 This is a scanning electron microscope image of the porous tin oxide material prepared in Example 1.
[0014] Figure 2 This is a scanning electron microscope image of the tin oxide material prepared in Preparation Example 4. Detailed Implementation
[0015] The endpoints and any values of the ranges disclosed herein 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 the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0016] The first aspect of the present invention provides a method for preparing porous tin oxide materials by low-temperature pyrolysis, the method comprising mixing alkoxytin with a C1-C10 monohydric alcohol and then calcining at 280-550°C.
[0017] In this invention, the calcination temperature can be 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 550℃, 540℃, 550℃, or any range of any two of the above. Using this method, tin oxide with a porous structure can be prepared at relatively low temperatures, reducing energy consumption.
[0018] According to the present invention, the number of carbon atoms in the alkoxytin can be selected within a wide range, but in order to make the tin oxide have a porous structure, preferably, the number of carbon atoms of the alkoxy group in the alkoxytin is 1-6.
[0019] According to the present invention, preferably, alkoxytin is at least one of tin methoxide, tin ethoxide, tin isopropoxide and tin tert-butoxide, more preferably tin ethoxide and / or tin isopropoxide.
[0020] According to the present invention, preferably, the C1-C10 monohydric alcohol is ethanol and / or propanol.
[0021] According to the present invention, in order to improve the yield of C2 hydrocarbons, the weight ratio of alkoxytin to C1-C10 monohydric alcohol is preferably 1:3-30 (e.g., 1:3, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:15, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:30, and any two of the above ranges).
[0022] According to the present invention, preferably, calcination is carried out in an oxidizing atmosphere. More preferably, calcination is carried out in an air atmosphere.
[0023] According to the present invention, preferably, the temperature is increased to 280-550°C at a heating rate of 3-8°C / min (for example, the heating rate can be 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min, 5°C / min, 5.5°C / min, 6°C / min, 6.5°C / min, 7°C / min, 7.5°C / min, 8°C / min, and any two of the above). Then, the temperature is maintained at this temperature for 5-12 hours (for example, the calcination time can be 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, and any two of the above).
[0024] A second aspect of the present invention provides a porous tin oxide material prepared by the method described above.
[0025] A third aspect of the present invention provides a method for methane oxidative coupling reaction, the method comprising: contacting a feed gas with the porous tin oxide material described above under methane oxidative coupling reaction conditions;
[0026] Alternatively, a porous tin oxide material can be prepared according to the method described above, and then the raw material gas can be contacted with the prepared porous tin oxide material under methane oxidative coupling reaction conditions.
[0027] According to the present invention, preferably, the conditions for the methane oxidative coupling reaction include: the feed gas is methane and oxygen, the reaction temperature is 700-800℃, and the space velocity of the feed gas is 5000-10000 mL / (g·h).
[0028] According to the present invention, preferably, the volume ratio of methane to oxygen in the raw material gas is 2-4:1.
[0029] The present invention will be described in detail below through embodiments. In the following embodiments,
[0030] "Alkoxy ratio" refers to the volume ratio of methane to oxygen in the feed gas.
[0031] Methane conversion rate = (molar amount of methane consumed in the reaction) / (initial molar amount of methane) × 100%.
[0032] Ethylene selectivity = (molar amount of methane consumed to produce ethylene / total molar amount of methane consumed) × 100%.
[0033] Ethane selectivity = (Moles of methane consumed to produce ethane) / (Total moles of methane consumed) × 100%.
[0034] C2 hydrocarbon selectivity = ethane selectivity + ethylene selectivity.
[0035] COx(CO+CO2) selectivity = (molar amount of methane consumed by CO and CO2 generated) / (total molar amount of methane consumed) × 100%.
[0036] C2 hydrocarbon yield = methane conversion rate × (ethane selectivity + ethylene selectivity) × 100%.
[0037] The reaction products were analyzed online using a gas chromatograph (Agilent Technologies, model 7890A). A dual-detection-channel, three-valve, four-column system was employed for analysis, with the FID detector connected to an alumina column for the analysis of CH4, C2H6, C2H4, C3H8, C3H6, and C4H. 10 C4H8, C n H mThe TCD detector is mainly used to detect CO, CO2, N2, O2, and CH4.
[0038] Preparation Example 1
[0039] Catalyst preparation method: Add tin ethanol to anhydrous ethanol (the weight ratio of tin ethanol to anhydrous ethanol is 1:10) and stir for 5 min to form solution A. Place solution A in a muffle furnace and heat to 550℃ at a heating rate of 8℃ / min (calcination atmosphere is air) for 5 h.
[0040] Scanning electron microscope image of porous tin oxide material as shown below Figure 1 As shown, from Figure 1 It can be seen that tin oxide materials have a porous structure with pore sizes ranging from 500 to 1600 nm.
[0041] Preparation Example 2
[0042] Catalyst preparation method: Tin isopropoxide was added to anhydrous ethanol (the weight ratio of tin isopropoxide to anhydrous ethanol was 1:24), stirred for 5 min, and mixed to form solution A. Solution A was placed in a muffle furnace and heated to 280℃ at a heating rate of 5℃ / min (calcination atmosphere was air) for 12 h.
[0043] The scanning electron microscope image of the porous tin oxide material is similar to that of Preparation Example 1 and will not be shown again.
[0044] Preparation Example 3
[0045] Catalyst preparation method: Add tin ethanol to anhydrous propanol (the weight ratio of tin ethanol to anhydrous ethanol is 1:6), stir for 5 min, and mix to form solution A. Place solution A in a muffle furnace and heat to 500℃ at a heating rate of 3℃ / min (calcination atmosphere is air) for 6 h.
[0046] The scanning electron microscope image of the porous tin oxide material is similar to that of Preparation Example 1 and will not be shown again.
[0047] Preparation Example 4
[0048] The preparation method was carried out in accordance with Example 1, except that the weight ratio of tin ethoxide to anhydrous ethanol was 1:60.
[0049] Scanning electron microscope image of the prepared tin oxide is shown below. Figure 2 As shown, from Figure 2 It can be seen that tin oxide materials are mostly granular.
[0050] Preparation Example 5
[0051] The preparation method was carried out in accordance with that of Example 1, except that the heating rate was 20 °C / min.
[0052] The scanning electron microscope image of the tin oxide material is similar to that in preparation example 4, and will not be shown again.
[0053] Preparation Example 6
[0054] The preparation method was the same as in Example 1, except that the heating rate was 1 °C / min.
[0055] The scanning electron microscope image of the porous tin oxide material is similar to that of Preparation Example 1 and will not be shown again.
[0056] Comparative Preparation Example 1
[0057] The preparation method was carried out in accordance with that of Example 1, except that tin ethoxide was replaced with an equal weight of tin nitrate.
[0058] The scanning electron microscope image of the tin oxide material is similar to that in preparation example 4, and will not be shown again.
[0059] Test Example 1
[0060] The porous tin oxide material obtained in Preparation Example 1 was used as a catalyst for the oxidative coupling reaction of methane. The reaction was carried out in a continuous flow fixed bed reactor, which was a quartz tube with an inner diameter of 10 mm and a length of 530 mm. The catalyst loading was 0.5 g, the reaction pressure was the pressure generated by the raw materials themselves, the reaction temperature was 700 °C, the alkane-to-oxygen ratio was 2.2, and the total gas flow rate of methane and oxygen was 5000 mL / (g·h). The catalyst performance evaluation results for the oxidative coupling reaction of methane after 1 hour of reaction are listed in Table 1.
[0061] Test Example 2
[0062] The porous tin oxide material obtained in Preparation Example 2 was used as a catalyst for the oxidative coupling reaction of methane. The reaction was carried out in a continuous flow fixed bed reactor, which was a quartz tube with an inner diameter of 10 mm and a length of 530 mm. The catalyst loading was 0.5 g, the reaction pressure was the pressure generated by the raw materials themselves, the reaction temperature was 720 °C, the alkane-to-oxygen ratio was 3, and the total gas flow rate of methane and oxygen was 7000 mL / (g·h). The catalyst performance evaluation results for the oxidative coupling reaction of methane after 1 hour of reaction are listed in Table 1.
[0063] Test Example 3
[0064] The porous tin oxide material obtained in Preparation Example 3 was used as a catalyst for the oxidative coupling reaction of methane. The reaction was carried out in a continuous flow fixed bed reactor, which was a quartz tube with an inner diameter of 10 mm and a length of 530 mm. The catalyst loading was 0.5 g, the reaction pressure was the pressure generated by the raw materials themselves, the reaction temperature was 780 °C, the alkane-to-oxygen ratio was 4, and the total gas flow rate of methane and oxygen was 10000 mL / (g·h). The catalyst performance evaluation results for the oxidative coupling reaction of methane after 1 hour of reaction are listed in Table 1.
[0065] Test Example 4
[0066] The catalyst performance was tested in the same manner as in Test Example 1, except that the material obtained in Preparation Example 4 was used as the catalyst for the methane oxidative coupling reaction. The reaction performance evaluation is shown in Table 1.
[0067] Test Example 5
[0068] The catalyst performance was tested in the same manner as in Test Example 1, except that the material obtained in Preparation Example 5 was used as the catalyst for the methane oxidative coupling reaction. The reaction performance evaluation is shown in Table 1.
[0069] Test Example 6
[0070] The catalyst performance was tested in accordance with the method described in Test Example 1, except that the material obtained in Preparation Example 6 was used as a catalyst for the methane oxidative coupling reaction. The reaction performance evaluation is shown in Table 1.
[0071] Comparative Test Example 1
[0072] The catalyst performance was tested in accordance with the method described in Test Example 1, except that the material obtained in Comparative Preparation Example 1 was used as a catalyst for the methane oxidative coupling reaction. The reaction performance evaluation is shown in Table 1.
[0073] Table 1
[0074] Methane conversion rate / % C2 hydrocarbon selectivity / % <![CDATA[CO x Selectivity / % C2 hydrocarbon yield / % Test Example 1 24.7 30.6 60.1 7.6 Test Example 2 23.2 30.1 61 7.0 Test Example 3 23.6 29.5 60.8 7.0 Test Example 4 15.1 20.2 70.5 3.1 Test Example 5 17.5 19.3 69.8 3.4 Test Example 6 22.8 23.7 66.9 5.4 Comparative Test Example 1 23.1 14.9 72.3 3.4
[0075] As can be seen from the results in Table 1, using the porous tin oxide material of the present invention as a catalyst for the methane oxidative coupling reaction can improve the C2 hydrocarbon selectivity. Preferably, the methane conversion rate using Examples 1-3 of the present invention is higher than 23%, and the C2 hydrocarbon selectivity is higher than 29%, demonstrating better catalytic performance.
[0076] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for the low temperature pyrogenic preparation of a porous tin oxide material, characterized in that The method involves mixing alkoxytin with a C1-C10 monohydric alcohol, then heating the mixture to 280-550°C at a heating rate of 3-8°C / min and maintaining the temperature at that temperature for 5-12 hours. The weight ratio of alkoxytin to C1-C10 monohydric alcohol is 1:3-30.
2. The method of claim 1, wherein, The number of carbon atoms in the alkoxytin group is 1-6.
3. The method of claim 1, wherein, The alkoxytin is at least one of tin ethoxide, tin ethanol, tin isopropoxide, and tin tert-butoxide.
4. The method of claim 3, wherein, Alkoxytin is tin ethoxide and / or tin isopropoxide.
5. The method of claim 1, wherein, C1-C10 monohydric alcohols are ethanol and / or propanol.
6. The method of claim 1, wherein, Calcination was carried out under an oxidizing atmosphere.
7. A method for a methane oxidation coupling reaction, characterized by, The method includes: preparing a porous tin oxide material according to any one of claims 1-6, and then contacting the prepared porous tin oxide material with a raw material gas under methane oxidative coupling reaction conditions.
8. The method of claim 7, wherein, The conditions for the methane oxidative coupling reaction include: the feed gas is methane and oxygen, the reaction temperature is 700-800℃, and the space velocity of the feed gas is 5000-10000 mL / (g·h).
9. The method of claim 8, wherein, The volume ratio of methane to oxygen in the feed gas is 2-4:1.