Ru / mgo material, preparation method and application thereof

Abstract

The application discloses a Ru / MgO material and a preparation method and application thereof. The preparation method of the Ru / MgO material comprises the following steps: S1, preparing a solid-liquid mixture containing a ruthenium source and a magnesium precursor; S2, placing the solid-liquid mixture in liquid nitrogen to obtain a solid containing the magnesium precursor coated with the ruthenium source; S3, performing vacuum freeze drying on the solid; S4, calcining at 500-700 DEG C for 4-6 h in an oxygen-containing atmosphere to obtain Ru2O3 / MgO; and S5, heating and reducing the Ru2O3 / MgO in a reducing atmosphere to obtain Ru / MgO. The Ru / MgO material is prepared by using the ruthenium source and the magnesium precursor as raw materials, freezing and synthesizing a solid containing the magnesium precursor coated with the surface of the ruthenium source by using liquid nitrogen, and performing calcining and reduction treatment. The Ru / MgO material can effectively solve the problem that ruthenium nanoparticles are easy to gradually deactivate at high temperature and reduce catalytic activity, and has good catalytic activity and high stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, and more particularly to a Ru / MgO material, a preparation method and applications thereof. BACKGROUND

[0002] In recent years, the excessive consumption of traditional fossil fuels has led to a continuous increase in the concentration of greenhouse gases such as CH4 and CO2 in the atmosphere, exacerbating the greenhouse effect and global warming. According to the prediction of the Intergovernmental Panel on Climate Change (IPCC), if the existing emission trajectory is maintained, the global temperature will rise by 3.2 ℃ by the end of this century, far exceeding the goal of limiting global warming to less than 1.5 ℃ set by the Paris Agreement; among them, the contribution rate of CO2 to the greenhouse effect is about 63%, and the global warming potential of CH4 is 65 times that of CO2. Therefore, developing efficient catalytic conversion technology to convert CH4 and CO2 into high-value chemicals is a promising solution to alleviate the greenhouse effect.

[0003] The methane double reforming reaction (methane-carbon dioxide-water double reforming), i.e. 3CH4+CO2+2H2O=4CO+8H2, can simultaneously activate and convert two greenhouse gases CH4 and CO2, which not only delays carbon deposition in the reforming reaction by adding water, but also adjusts the H2 / CO ratio by introducing carbon dioxide, to synthesize n (H2) / n (CO) of about 2, which provides raw materials for the synthesis of green methanol, light olefins and other high-value chemicals, while effectively alleviating the pressure of greenhouse gas emission reduction and improving the efficient utilization of carbon resources. Therefore, the use of methane double reforming technology to produce synthesis gas is a C1 chemical process with great application prospect, which has important significance in the fields of environmental protection, energy transformation and scientific research.

[0004] Non-noble metal nickel-based catalysts have been widely studied for catalyzing methane reforming reactions due to their low price and abundant production. However, the nickel-based catalyst has a low activation energy for methane cracking, which leads to the deep cracking of methane on its surface. The high cracking rate leads to the rapid nucleation and growth of carbon species on the catalyst surface and covers the active sites, resulting in deactivation. In addition, due to its low Tamman temperature (about 590 ℃), it is prone to sintering under high temperature conditions.

[0005] However, compared with non-noble transition metals, noble metal-based catalysts (e.g. Ru) generally exhibit excellent activity and carbon deposition resistance, but due to its high production cost, it greatly limits the application in industry. In this regard, the prior art has developed a low Ru loading (<1 wt%) catalyst, but there are the following problems: on the one hand, the conversion rate of the low Ru loading catalyst in the methane double reforming reaction is much lower than that of the high Ru loading (>1 wt%) catalyst; on the other hand, the Ru catalyst prepared by the existing preparation method has low dispersion of the active component Ru under low loading, and is easy to agglomerate at high temperature, thereby reducing the catalytic activity and shortening the service life. If the conversion rate of the catalytic reaction is to be maintained above a certain target, new catalysts need to be replaced. Since the catalytic conversion rate of the low Ru loading catalyst is lower than that of the high Ru loading catalyst, the replacement frequency of the low Ru loading catalyst is higher than that of the high Ru loading catalyst. In summary, there is little cost advantage in using the low Ru loading catalyst. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of Ru / MgO material, the Ru / MgO material prepared by the preparation method has good catalytic activity and high stability, and has a long service life.

[0007] Another purpose of the present application is to provide the Ru / MgO material prepared by the above preparation method.

[0008] Still another purpose of the present application is to provide the application of the above Ru / MgO material in the catalytic methane double reforming reaction.

[0009] To solve the above technical problems, the technical scheme adopted by the present application is:

[0010] In a first aspect, a preparation method of Ru / MgO material includes the following steps:

[0011] S1. A solid-liquid mixture containing a ruthenium source and a magnesium precursor is prepared;

[0012] S2. The solid-liquid mixture is placed in liquid nitrogen to obtain a solid containing a ruthenium source coated magnesium precursor;

[0013] S3. The solid is vacuum freeze-dried;

[0014] S4. Calcining at 500-700 ℃ for 4-6 h in an oxygen-containing atmosphere to obtain Ru2O3 / MgO;

[0015] S5. The Ru2O3 / MgO is heated and reduced in a reducing atmosphere to obtain Ru / MgO.

[0016] This invention uses ruthenium source and magnesium precursor as raw materials. A solid containing ruthenium source coated on the surface of the magnesium precursor is synthesized by liquid nitrogen cryogenics. After calcination and reduction treatment, magnesium oxide with moderately strong alkalinity and high specific surface area is formed, and Ru nanoparticles are anchored on the MgO surface to obtain a Ru / MgO material. The Ru / MgO material effectively solves the problem of ruthenium nanoparticles gradually deactivating at high temperatures, thus reducing catalytic activity. Therefore, the Ru / MgO material of this invention exhibits good catalytic activity and high stability.

[0017] The catalytic performance of Ru-based catalysts depends on the physicochemical properties of the support (such as specific surface area, acidity and basicity, oxygen storage capacity, etc.) and the preparation method of the material. These factors together determine the dispersion of active metal Ru and the adsorption and activation capacity of reactants, thus significantly affecting the catalytic performance.

[0018] Studies have revealed that the strong acidity of catalyst supports typically accelerates carbon deposition, leading to catalyst deactivation. Therefore, the Lewis acidity of ZrO2 and Al2O3 causes deep cracking of methane, forming carbon species that are difficult to oxidize. Furthermore, when inert SiO2 is used as a catalyst support, the active metal Ru is prone to sintering at high temperatures due to the weak metal-support interaction.

[0019] When alkaline earth metal oxide MgO is used as a support, its strong Lewis basicity is beneficial to CO2 adsorption and activation, promoting the formation of active O* species from CO2 dissociation to eliminate carbon precursors. Catalysts using MgO as a support achieve a longer lifetime compared to those using ZrO2, Al2O3, or SiO2. However, research has shown that the catalytic activity and stability of Ru / MgO obtained using existing preparation methods (such as wet impregnation to prepare MgO-supported Ru) are still not high and need further improvement. This invention uses alkaline earth metal oxide MgO as a support. The preparation method of this invention can obtain MgO with a large specific surface area and enable strong metal-support interaction between MgO and active metal Ru, promoting the dispersion of active metal Ru, improving the atomic utilization rate of active metal Ru, effectively inhibiting sintering of active sites, and thus improving stability.

[0020] Optionally, in step S1, the ruthenium source and magnesium precursor are dispersed in water to prepare a solid-liquid mixture containing the ruthenium source and magnesium precursor. In one embodiment, a target mass of the ruthenium source and magnesium precursor is weighed and dissolved or dispersed in deionized water, and the resulting solid-liquid mixture is ultrasonicated.

[0021] Conventional water-soluble ruthenium sources in the art can be used in this invention. Optionally, the ruthenium source is one or more of ruthenium chloride, ruthenium acetate, ruthenium nitrite, or ruthenium acetylacetonate; or, the ruthenium source is a solution containing one or more of ruthenium chloride, ruthenium acetate, ruthenium nitrite, or ruthenium acetylacetonate. Preferably, the ruthenium source is ruthenium chloride.

[0022] Optionally, the magnesium source is one or more of magnesium chloride, magnesium nitrate, magnesium hydroxide, magnesium carbonate, or magnesium acetate. Preferably, the magnesium source is magnesium hydroxide.

[0023] In step S3 of this invention, the solid is subjected to vacuum freeze-drying. Optionally, the temperature of the vacuum freeze-drying is -50 to -20 °C. The time of the vacuum freeze-drying is 1 to 3 days, preferably 2 to 3 days.

[0024] In step S4 of this invention, Ru2O3 / MgO is obtained by calcination at 500-700 °C for 4-6 h in an oxygen-containing atmosphere. In one embodiment, the calcination temperature is 700 °C and the calcination time is 4 h. Optionally, the heating rate of the calcination is set to 2 °C / min.

[0025] Optionally, the oxygen-containing atmosphere is one or more of static or flowing air, or a 5% O2 / N2 mixture.

[0026] In step S5 of this invention, the heating reduction temperature is 450~650 ℃, and the reduction time is 1~2 h. The heating reduction heating rate is 5~10 ℃ / min.

[0027] Optionally, the reducing atmosphere is one or more of H2, H2 / N2, or H2 / Ar mixture.

[0028] The preparation method described in this invention can be used to prepare Ru / MgO with low loading. The Ru loading in the Ru / MgO is 0.1~0.5 wt%. The loading refers to the mass fraction of the catalytically active component Ru in the entire Ru / MgO.

[0029] In a second aspect, the present invention also provides a Ru / MgO material, wherein the Ru / MgO material is prepared by the preparation method described in the first aspect.

[0030] In the Ru / MgO material of the present invention, the MgO carrier prepared by the preparation method has a large specific surface area and strong Lewis basicity, which can promote the dispersion of active metal Ru, thereby improving the anti-carbon deposition and anti-sintering ability of the Ru / MgO material. As a result, the Ru / MgO material has good catalytic activity and stability, and can effectively catalyze the methane dual reforming syngas reaction for use in the synthesis of downstream high value-added chemicals.

[0031] Therefore, the application of the Ru / MgO material described in this invention as a catalyst in catalytic reactions, especially in the methane double reforming reaction, should also be within the scope of protection of this invention.

[0032] Thirdly, the present invention provides the application of the Ru / MgO material in the catalytic double reforming reaction of methane.

[0033] The Ru / MgO material described in this invention showed no significant deactivation during the methane double reforming reaction at 800 °C for at least 100 h, with methane conversion maintained at 82-84% and carbon dioxide conversion maintained at 75-79%, yielding syngas with an n(H2) / n(CO) ratio of approximately 2, which is beneficial for the downstream synthesis of green methanol.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] This invention uses ruthenium source and magnesium precursor as raw materials. A solid containing ruthenium source coated on the surface of the magnesium precursor is synthesized by liquid nitrogen cryogenics. After calcination and reduction treatment, magnesium oxide with moderately strong alkalinity and high specific surface area is formed, and Ru nanoparticles are anchored on the MgO surface to obtain a Ru / MgO material. The Ru / MgO material effectively solves the problem of ruthenium nanoparticles gradually deactivating at high temperatures, thus reducing catalytic activity. Therefore, the Ru / MgO material of this invention exhibits good catalytic activity and high stability. Attached Figure Description

[0036] Figure 1 The image shows the N2 adsorption-desorption isotherm and pore size distribution curve of the catalyst in Example 3.

[0037] Figure 2 The graph shows the test results of catalyst stability for the examples and comparative examples; wherein, Figure 2 a is a graph showing the test results of Example 3; Figure 2 b is the test result graph of Comparative Example 1; Figure 2 c shows the test results of Comparative Example 3; Figure 2 d shows the test results for Comparative Example 4.

[0038] Figure 3 The graph shows the test results of the catalyst in Example 3 participating in the catalytic reaction for 100 h. Detailed Implementation

[0039] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0040] The sources of the raw materials used in the following examples and comparative examples are as follows:

[0041] Anhydrous ruthenium trichloride, Maclean, molecular weight: 207.42, CAS No.: 10049-08-8.

[0042] Ruthenium acetate, Maclean, purity: 99%, molecular weight: 278.20, CAS number: 72196-32-8.

[0043] Ruthenium nitrite nitrate, Maclean, molecular weight: 318.1, CAS No.: 34513-98-9.

[0044] Ruthenium acetylacetonate, Maclean, purity: 99.95%, molecular weight: 398.39, CAS number: 14284-93-6.

[0045] Commercial MgO, Maclean, purity: 99.9%, molecular weight: 40.30, grade: M761792, CAS number: 1309-48-4.

[0046] Magnesium hydroxide, Maclean, purity: ≥99.0%, molecular weight: 58.32, CAS number: 1309-42-8.

[0047] Anhydrous magnesium chloride, Maclean, purity: 99.9%, molecular weight: 95.21, CAS number: 7786-30-3.

[0048] Magnesium nitrate hexahydrate, Guangzhou Chemical Reagent Factory, molecular weight: 256.41, CAS No.: 13446-18-9.

[0049] Magnesium carbonate hydrate, Maclean, molecular weight: 84.31, CAS No.: 23389-33-5.

[0050] Magnesium acetate, Maclean, purity: 98%, molecular weight: 142.39, CAS number: 142-72-3.

[0051] Examples 1-3

[0052] The purpose of Examples 1-3 is to prepare Ru / MgO materials with different Ru loadings (as shown in Table 1). The specific preparation methods are as follows:

[0053] Accurately weigh appropriate amounts of ruthenium trichloride and magnesium hydroxide, dissolve or disperse them in 30 mL of deionized water, sonicate for 30 min, and stir for 2 h to form a homogeneous solid-liquid mixture. Quickly pour the homogeneous solid-liquid mixture into a polytetrafluoroethylene liner containing liquid nitrogen to obtain a solid containing a ruthenium source coated on the surface of a magnesium precursor. Then, freeze-dry the solid at -50 °C for 48 ℃ (2 d) to obtain the precursor Ru. 3+ / Mg(OH)2. The resulting Ru 3+ Mg(OH)₂ was placed in a muffle furnace and calcined at 700 °C for 4 h in air at a heating rate of 2 °C / min to obtain Ru₂O₃ / MgO. Finally, Ru₂O₃ / MgO was reduced in situ at 650 °C for 2 h in a 10% H₂ / N₂ reducing atmosphere.

[0054] Table 1

[0055]

[0056] Examples 4-7

[0057] The purpose of Examples 4-7 is to investigate the effect of different magnesium precursors (such as MgCl2, MgCO3, etc.) on the catalytic performance of Ru / MgO materials. The specific preparation methods are as follows:

[0058] Accurately weigh the appropriate amounts of ruthenium trichloride and magnesium precursor (see Table 2 for details) and dissolve or disperse them in 30 mL of deionized water. Sonicate for 30 min and stir for 2 h to form a homogeneous solid-liquid mixture. Quickly pour the homogeneous solid-liquid mixture into a polytetrafluoroethylene liner containing liquid nitrogen to obtain a solid containing a ruthenium source coated on the surface of the magnesium precursor. Then, freeze-dry the solid at -50 °C under vacuum for 48 h to obtain a product containing Ru... 3+ / Mg precursor, the resulting Ru 3+ The Mg precursor was placed in a muffle furnace and calcined at 700 °C for 4 h in air atmosphere to obtain Ru₂O₃ / MgO. Finally, Ru₂O₃ / MgO was reduced in situ at 650 °C for 2 h in a 10% H₂ / N₂ reducing atmosphere.

[0059] Table 2

[0060]

[0061] Examples 8-10

[0062] The purpose of Examples 8-10 is to investigate the effect of different ruthenium sources (see Table 3) on the catalytic performance of Ru / MgO materials. The specific preparation methods are as follows:

[0063] Accurately weigh the appropriate amounts of ruthenium source and magnesium hydroxide, dissolve or disperse them in 30 mL of deionized water, sonicate for 30 min, and stir for 2 h to form a homogeneous solid-liquid mixture. Quickly pour the homogeneous solid-liquid mixture into a polytetrafluoroethylene liner containing liquid nitrogen to obtain a solid containing ruthenium source coated on the surface of the magnesium precursor. Then, freeze-dry the solid at -50 ℃ under vacuum for 48 ℃ (2 d) to obtain the precursor Ru. 3+ / Mg(OH)2. The resulting Ru 3+ Mg(OH)₂ was placed in a muffle furnace and calcined at 700 °C for 4 h in air at a heating rate of 2 °C / min to obtain Ru₂O₃ / MgO. Finally, Ru₂O₃ / MgO was reduced in situ at 650 °C for 2 h in a 10% H₂ / N₂ reducing atmosphere.

[0064] Table 3

[0065]

[0066] Examples 11-12

[0067] Examples 11-12 aim to investigate the effect of different conditions in the preparation method on the catalytic performance of Ru / MgO materials. Ru / MgO with a loading of 0.5 wt% was prepared using the following specific preparation method:

[0068] Example 11: Unlike the preparation method in Example 3, the vacuum freeze-drying process in Example 11 involves a vacuum freeze-drying temperature of -20 °C and a freeze-drying time of 1 day.

[0069] Example 12: Unlike the preparation method of Example 3, the preparation method of Example 12 involves calcining the precursor Ru in an oxygen-containing atmosphere. 3+ When calcining Ru2O3 / MgO, the calcination temperature is 500 ℃ and the calcination time is 6 h; when reducing Ru2O3 / MgO by heating, the reduction temperature is 450 ℃ and the reduction time is 1 h.

[0070] Comparative Example 1

[0071] The purpose of this comparative example is to investigate the effect of the traditional wet impregnation method on the catalytic performance of Ru / MgO materials. A Ru / MgO material with a loading of 0.5 wt% was prepared using the following method:

[0072] Accurately weigh the appropriate amounts of ruthenium trichloride and magnesium hydroxide, dissolve or disperse them in 30 mL of deionized water, sonicate for 30 min, and stir for 2 h to form a homogeneous solid-liquid mixture. Then, place the mixture in a 100 ℃ oven overnight to thoroughly remove moisture, obtaining the precursor Ru. 3+ / Mg(OH)2. The resulting Ru 3+ Mg(OH)₂ was placed in a muffle furnace and calcined at 700 °C for 4 h in air atmosphere to obtain Ru₂O₃ / MgO. Finally, Ru₂O₃ / MgO was reduced in situ at 650 °C for 2 h in a 10% H₂ / N₂ reducing atmosphere.

[0073] Comparative Example 2

[0074] In this comparative example, commercially available MgO was used as a support to load Ru, and Ru / MgO with a loading of 0.5 wt% was prepared using the traditional wet impregnation method. The specific preparation method is as follows:

[0075] Accurately weigh the appropriate amounts of ruthenium trichloride and MgO, dissolve or disperse them in 30 mL of deionized water, sonicate for 30 min, and stir for 2 h to form a homogeneous solid-liquid mixture. Then, place the mixture in a 100 ℃ oven overnight to thoroughly remove moisture, obtaining the precursor Ru. 3+ / MgO. The resulting Ru 3+ The MgO was placed in a muffle furnace and calcined at 700 °C for 4 h in air at a heating rate of 2 °C / min to obtain Ru₂O₃ / MgO. Finally, the Ru₂O₃ / MgO was reduced in situ at 650 °C for 2 h in a 10% H₂ / N₂ reducing atmosphere.

[0076] Comparative Example 3

[0077] In this comparative example, commercially available MgO was used as a support to load Ru, and Ru / MgO with a loading of 0.5 wt% was prepared. The specific preparation method is as follows:

[0078] Accurately weigh appropriate amounts of ruthenium trichloride and MgO, dissolve or disperse them in 30 mL of deionized water, sonicate for 30 min, and stir for 2 h to form a homogeneous solid-liquid mixture. Quickly pour the homogeneous solid-liquid mixture into a polytetrafluoroethylene liner containing liquid nitrogen to obtain a solid containing a mixture of ruthenium source and MgO. Then, freeze-dry the solid at -50 °C under vacuum for 2 days to obtain Ru. 3+ / MgO. The resulting Ru 3+ The MgO was placed in a muffle furnace and calcined at 700 °C for 4 h in air at a heating rate of 2 °C / min to obtain Ru₂O₃ / MgO. Finally, the Ru₂O₃ / MgO was reduced in situ at 650 °C for 2 h in a 10% H₂ / N₂ reducing atmosphere.

[0079] Comparative Example 4

[0080] The purpose of this comparative example is to investigate the effect of the traditional wet impregnation method on the catalytic performance of Ru / MgO materials. A Ru / MgO material with a loading of 1 wt% was prepared using the following method:

[0081] Accurately weigh the appropriate amounts of ruthenium trichloride and magnesium hydroxide, dissolve or disperse them in 30 mL of deionized water, sonicate for 30 min, and stir for 2 h to form a homogeneous solid-liquid mixture. Then, place the mixture in a 100 ℃ oven overnight to thoroughly remove moisture, obtaining the precursor Ru. 3+ / Mg(OH)2. The resulting Ru 3+ Mg(OH)₂ was placed in a muffle furnace and calcined at 700 °C for 4 h in air atmosphere to obtain Ru₂O₃ / MgO. Finally, Ru₂O₃ / MgO was reduced in situ at 650 °C for 2 h in a 10% H₂ / N₂ reducing atmosphere.

[0082] Characterization and performance testing

[0083] 1. Characterization

[0084] The catalysts prepared in the above examples and comparative examples were characterized using the following methods.

[0085] 1) ICP-OES testing:

[0086] The actual loading of the active metal Ru in the catalysts prepared in the above examples and comparative examples was tested using ICP-OES technology, and the results are shown in Table 4. The ICP-OES test showed that the actual loading of the active metal Ru was essentially the same as the theoretical loading.

[0087] Table 4

[0088]

[0089] 2) N2 physical adsorption-desorption test:

[0090] Specific surface area and pore structure were assessed using a gas adsorption analyzer (Micromeritics ASAP 2460), and the specific surface area was calculated using the Brunauer-Emmett-Teller (BET) method. Specifically, samples were degassed under vacuum at 300 °C prior to N2 physisorption measurements. N2 adsorption / desorption isotherms were collected at -196 °C. The total specific surface area was determined using the Brunauer-Emmett-Teller (BET) equation based on the linear portion of the adsorption isotherms. The total pore volume and average pore size were calculated using the Barrett-Joyner-Halenda (BJH) model.

[0091] like Figure 1 As shown, the catalyst prepared in Example 3 exhibits a characteristic type IV isotherm with an H3-type hysteresis loop, indicating the presence of a unique mesoporous structure. Calculations show that the BET specific surface area of ​​the catalyst prepared in Example 3 is 15.66 m². 2 g −1 The total pore volume is 0.17 cm³. 3 g −1 The average pore size is 36.25 nm.

[0092] 2. Performance Testing

[0093] To evaluate the catalytic performance of the catalyst, a double reforming reaction of methane was carried out in a fixed-bed reactor with an inner diameter of 8 mm under atmospheric pressure. The basic test procedures and conditions were as follows: A quartz tube containing 200 mg of catalyst (20–40 mesh) was placed vertically in a fixed-bed furnace. Pure CH4, CO2, and N2 feed gases were introduced at flow rates of 36 mL / min, 12 mL / min, and 12 mL / min, respectively, using N2 as an internal standard. Liquid water was introduced using a syringe pump (flow rate of 0.0193 mL / min), preheated, vaporized, and mixed with the other feed gases before being injected into the fixed-bed reactor. The stoichiometric ratio was fixed at CH4:CO2:N2:H2O = 3:1:1:2, and the WHSV was approximately 25000 mL g⁻¹ Cat. h -1 Residual water was separated using a gas-liquid separator. Measurements were performed using a gas chromatograph equipped with a thermal conductivity detector (TCD). The gas chromatograph used a molecular sieve 5A column to separate H2, N2, CH4, and CO, and a Porapak Q column to separate CO2.

[0094] Conversion rates of CH4 and CO2 (Con.CH4 and Con.CO2) n (H2) / n (CO) is calculated as follows:

[0095]

[0096] In the formula, In and out refer to the peak area of ​​the gas chromatograph, and F H2 and F CO This refers to the correction factors for H2 and CO. V CH4 For methane flow rate (2.16 L / h), V m The molar volume of the gas under experimental conditions is 22.4 L / mol.

[0097] 1) Catalytic activity

[0098] Based on the basic test steps and conditions described above, the test temperature range was controlled at 650~800 ℃, with a temperature interval of 50 ℃, a heating rate of 10 ℃ / min, and each temperature point was held for 2 h. The test results of Examples 1~7 and Comparative Example 1 are shown in Table 5:

[0099] Table 5

[0100]

[0101] Based on the basic test steps and conditions described above, the test temperature was controlled at 800 ℃ and the heating rate was 10 ℃ / min. The test results of Examples 8-12 and Comparative Examples 2-4 after running for 1 hour at 800 ℃ are shown in Table 6:

[0102] Table 6

[0103]

[0104] 2) Catalyst stability

[0105] To evaluate the catalytic stability of the catalyst, based on the basic test procedures and conditions described above, the test temperature was controlled at 800 °C, the test time at 40 h, and the heating rate at 10 °C / min. The test results of Examples 3 and Comparative Examples 1, 3, and 4 are as follows: Figure 2 As shown.

[0106] pass Figure 2 a and Figure 2 A comparison of examples b, 2c, and 2d shows that the catalyst prepared in Example 3 has significantly higher stability than the catalysts prepared in Comparative Examples 1, 3, and 4. Specifically, a comparison between Example 3 and Comparative Example 1 demonstrates that, under the same or similar Ru loading, the preparation method of this invention can not only effectively improve the CH4 and CO2 conversion rates of the catalyst but also extend its service life.

[0107] By comparing Example 3 with Comparative Example 3, it can be seen that although Comparative Example 3 uses the same preparation method as the present invention, its catalytic activity and long-term stability are significantly inferior to the support system derived from magnesium precursors such as magnesium hydroxide because it directly uses commercial MgO as the support.

[0108] By comparing Example 3 with Comparative Example 4, it can be seen that although the Ru loading of the catalyst prepared in Example 3 is only half that of Comparative Example 4, the CH4 conversion rate and CO2 conversion rate of Example 3 are slightly higher than those of Comparative Example 4, and the stability of Example 3 is significantly better than that of Comparative Example 4.

[0109] To evaluate the long-term catalytic stability of the catalyst in Example 3, based on the basic test steps and conditions described above, the test temperature was controlled at 800 °C, the test time at 100 h, and the heating rate at 10 °C / min.

[0110] Test results are as follows Figure 3 As shown, after the catalyst prepared in Example 3 continuously catalyzes the double reforming of methane at 800 °C for 100 hours, its CH4 conversion rate and CO2 conversion rate still do not show a decreasing trend, indicating that the catalyst prepared in Example 3 has high stability.

[0111] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a Ru / MgO material, characterized in that, Includes the following steps: S1. A solid-liquid mixture containing a ruthenium source and a magnesium precursor is prepared by dispersing a ruthenium source and a magnesium precursor in water; wherein the ruthenium source is one or more of ruthenium chloride, ruthenium acetate, ruthenium nitrite, or ruthenium acetylacetonate; and the magnesium precursor is one or more of magnesium chloride, magnesium nitrate, magnesium hydroxide, magnesium carbonate, or magnesium acetate. S2. The solid-liquid mixture is placed in liquid nitrogen to obtain a solid containing a ruthenium source-coated magnesium precursor; S3. The solid is subjected to vacuum freeze-drying; the temperature of the vacuum freeze-drying is -50~-20℃; S4. Calcination at 500-700 ℃ for 4-6 h under an oxygen-containing atmosphere yields Ru2O3 / MgO; S5. The Ru2O3 / MgO is reduced by heating under a reducing atmosphere to obtain Ru / MgO.

2. The method for preparing the Ru / MgO material according to claim 1, characterized in that, In step S4, the oxygen-containing atmosphere is one or more of static or flowing air and a 5% O2 / N2 mixture.

3. The method for preparing the Ru / MgO material according to claim 1, characterized in that, In step S5, the heating and reduction temperature is 450~650 ℃, and the reduction time is 1~2 h; the reducing atmosphere is one or more of H2, H2 / N2 or H2 / Ar mixture.

4. The method for preparing the Ru / MgO material according to claim 1, characterized in that, The Ru loading in the Ru / MgO is 0.1~0.5 wt%.

5. A Ru / MgO material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the Ru / MgO material according to claim 5 in the catalytic double reforming of methane.

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