High-stability nickel-based methane carbon dioxide reforming catalyst and preparation method thereof
NiO is supported on the SiO2 support by magnesium thermal reduction method to form a surface structure of Ni particles coated with MgO, which solves the problem of carbon deposits and sintering of Ni-based catalysts at high temperatures, and achieves high stability and high activity of the catalyst, which is suitable for methane carbon dioxide reforming reaction.
Patent Information
- Application Number
- CN202510554420.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-29
- Publication Date
- 2025-07-29
AI Technical Summary
Traditional Ni-based catalysts are prone to carbon deposits and sintering in high-temperature methane carbon dioxide reforming reaction, resulting in a decrease in catalyst activity and stability, limiting their industrial applications.
NiO is loaded on SiO2 support by magnesium thermal reduction method, and NiO is reduced by magnesium steam to form the surface structure of Ni particles coated with MgO, inhibiting carbon deposits and improving catalyst stability.
It enhances the resistance to carbon deposits of the catalyst, improves the stability and activity of the catalyst, and extends the service life of the catalyst.
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Figure CN120381844A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a highly stable nickel-based methane carbon dioxide reforming catalyst and a preparation method thereof. Background Art
[0002] The methane carbon dioxide reforming reaction (DRM) can convert two major greenhouse gases, methane and carbon dioxide, into syngas (H2 / CO≈1). The syngas can be further used for the production of liquid fuels, chemicals, and high-value-added materials, which is of great significance in the comprehensive utilization of carbon resources and alleviating the greenhouse effect. However, this reaction is a strongly endothermic reaction and needs to be carried out at high temperatures (700 - 1000 °C), which makes the catalyst prone to carbon deposition and sintering during the reaction process, resulting in a decrease in the activity and stability of the catalyst, severely limiting its industrial application.
[0003] Ni-based catalysts are considered to be one of the most promising DRM catalysts due to their high catalytic activity and relatively low cost. However, under high-temperature reaction conditions, Ni particles in traditional Ni-based catalysts are prone to agglomeration and growth, and a large amount of carbon deposition is generated on the catalyst surface, covering the active sites, resulting in rapid deactivation of the catalyst. Therefore, it is crucial to develop a preparation method that can effectively inhibit the sintering of Ni particles and the generation of carbon deposition, thereby improving the stability of Ni-based catalysts. Summary of the Invention
[0004] The purpose of the present invention is to provide a preparation method of a highly stable nickel-based methane carbon dioxide reforming catalyst, which can enhance the anti-carbon deposition performance of the methane carbon dioxide reforming catalyst and improve the stability of the methane carbon dioxide reforming catalyst.
[0005] Another purpose of the present invention is to provide a highly stable nickel-based methane carbon dioxide reforming catalyst.
[0006] The technical solution provided by the present invention is as follows:
[0007] A preparation method of a highly stable nickel-based methane carbon dioxide reforming catalyst, comprising the following steps:
[0008] Step 1: Load NiO on a SiO2 support to obtain a NiO / SiO2 precursor;
[0009] Step 2: Place the NiO / SiO2 precursor and a magnesium-based metal in a heating furnace respectively, and introduce an inert gas into the heating furnace; heat the heating furnace until the magnesium-based metal melts to generate magnesium vapor, and carry out a magnesiothermic reduction reaction on the NiO / SiO2 precursor to obtain a nickel-based methane carbon dioxide reforming catalyst.
[0010] Preferably, the SiO2 support is fumed silica, mesoporous silica or SiO2 microspheres.
[0011] Preferably, in the first step, the method for loading NiO on the SiO2 support is the impregnation method, the precipitation method or the chemical vapor deposition method.
[0012] Preferably, the magnesium-based metal is magnesium or magnesium alloy.
[0013] Preferably, in the second step, the temperature of the magnesium thermal reduction reaction is 600°C to 1000°C, and the reaction time is 10 min to 2 h.
[0014] Preferably, in the second step, the flow rate of the inert gas introduced is 50 mL / min to 200 mL / min.
[0015] Preferably, the inert gas is Ar or He.
[0016] A highly stable nickel-based methane dry reforming catalyst is prepared by using the preparation method of the highly stable nickel-based methane dry reforming catalyst described above.
[0017] The beneficial effects of the present invention are as follows:
[0018] The preparation method of the highly stable nickel-based methane dry reforming catalyst provided by the present invention uses magnesium vapor to replace hydrogen to reduce Ni, and at the same time, the Mg vapor is converted into MgO to coat the surface of Ni particles, so that the nickel-based methane dry reforming catalyst forms a "surface coating" structure, having high catalytic activity and high stability. Description of the Drawings
[0019] Figure 1 is a schematic diagram of the magnesium thermal reduction reaction device described in the present invention.
[0020] Figure 2 is a graph of CO2 conversion rates in each example and comparative example.
[0021] Figure 3 is a graph of CH4 conversion rates in each example and comparative example.
[0022] Figure 4 is a graph of the H2 / CO ratio in the syngas in each example and comparative example.
[0023] Figure 5 is a TG characterization graph of the catalyst in each example and comparative example.
[0024] Figure 6 is a graph of the HRTEM characterization of the catalyst in each example and comparative example after the catalytic reaction;
[0025] Among them, (a) in 6 is the HRTEM characterization of Comparative Example 1, Figure 6 (b)-(e) are the HRTEM characterizations of Examples 1-4, respectively.
[0026] Figure 7 This is the HRTEM characterization diagram of the catalyst after magnesium thermal reduction in Example 3.
[0027] Figure 8 The X-ray diffraction (XRD) characterization diagrams of the catalysts of various examples and comparative examples after reduction. DETAILED DESCRIPTION
[0028] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.
[0029] The present invention provides a method for preparing a high-stability nickel-based methane carbon dioxide reforming catalyst, and the specific process is as follows.
[0030] 1. Load NiO on SiO2 carrier to obtain NiO / SiO2 precursor.
[0031] Wherein, the SiO2 carrier is gas-phase SiO2, mesoporous SiO2 or SiO2 microspheres.
[0032] Methods for loading NiO onto SiO2 carriers include, but are not limited to, impregnation, precipitation, or vapor deposition. The nickel salt precursors used in the loading process are common nickel salts such as nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, and nickel acetylacetonate.
[0033] 2. The NiO / SiO2 precursor is subjected to magnesium thermal reduction to obtain a highly stable MgO-Ni / SiO2 methane carbon dioxide reforming catalyst.
[0034] The NiO / SiO2 precursor and the magnesium-based metal are respectively placed in a heating furnace, and an inert gas is introduced into the heating furnace; the heating furnace is heated to melt the magnesium-based metal to generate magnesium vapor, and the magnesium vapor is carried by the inert gas to bring the NiO / SiO2 precursor into contact with the magnesium vapor, undergoing a magnesium thermal reduction reaction to obtain a nickel-based methane carbon dioxide reforming catalyst.
[0035] Wherein, the magnesium-based metal is magnesium alone or a magnesium alloy.
[0036] The temperature of magnesium thermal reduction is 600 °C to 1000 °C, and the reaction time is 10 min to 2 h. By reasonably controlling the reaction time of magnesium thermal reduction, the reduction degree of NiO and the coverage thickness of MgO on the catalyst surface can be controlled, so that the metal-support interaction of the catalyst is increased, the adsorption of CO2 is enhanced, and then the generated carbon is oxidized, the anti-coking performance is enhanced, and the stability of the dry reforming of methane catalyst is improved.
[0037] The flow rate of the inert gas introduced is 50 mL / min to 200 mL / min.
[0038] Preferably, the inert gas is Ar gas or He gas.
[0039] The highly stable methane carbon dioxide reforming catalyst prepared by the preparation method of the highly stable nickel-based methane carbon dioxide reforming catalyst provided by the present invention combines the strong reducibility and volatility of Mg, uses magnesium vapor to reduce Ni instead of hydrogen, and reduces divalent Ni during the magnesium thermal process (reducing Ni 2+ to nano-Ni particles), while Mg vapor is converted into MgO and adheres to the surface of Ni particles. A surface coating structure is formed, which can cover the highly active sites on the surface of Ni particles and inhibit CH4 cracking. At the same time, MgO, as a basic oxide, can enhance the adsorption activation of CO2, so the anti-coking ability of the catalyst can be effectively improved.
[0040] Example 1
[0041] Add 2 mL of TEOS to a mixed solution composed of 15 mL of water and 35 mL of isopropanol, and stir at high speed for 5 min. Then add 1 mL of ammonia water and continue stirring for 2 h. The white solid in the product is obtained by centrifugal separation and dried at 60 °C for 24 h to obtain monodisperse SiO2 microspheres.
[0042] In the loading process, first measure the water absorption of the SiO2 microspheres, and add a certain amount of nickel salt precursor according to the preset Ni content (here set to 10% of the mass of Ni in the NiO / SiO2 precursor). The nickel salt precursor is nickel nitrate. After standing for 24 h, it is placed in an oven, dried and then placed in a muffle furnace for calcination (calcined at 800 °C for 4 h) to obtain the NiO / SiO2 precursor.
[0043] The AZ91D magnesium alloy block is polished with sandpaper to remove the surface oxide layer, and then placed in an alumina porcelain boat. The Ni / SiO2 precursor powder is evenly placed in another porcelain boat. The two porcelain boats are placed in a tube furnace in parallel (the reaction device is as Figure 1 shown). After evacuating the oxygen in the reaction system by multiple vacuum extractions, high-purity Ar is introduced into the tube furnace, and the tube furnace is heated to 800 °C. The reduction time at this temperature is set to 15 min to prepare the Mg-Ni / SiO2 catalyst.
[0044] Example 2
[0045] Add 2 mL of TEOS to a mixed solution composed of 15 mL of water and 35 mL of isopropanol, and stir at high speed for 5 min. Subsequently, add 1 mL of ammonia water and continue stirring for 2 h. The white solid in the product is obtained by centrifugation and dried at 60 °C for 24 h to obtain monodisperse SiO2 microspheres.
[0046] In the loading process, first measure the water absorption of the SiO2 microspheres, and add a certain amount of nickel salt precursor according to the pre-set Ni content (set here as 10% of the mass of Ni in the NiO / SiO2 precursor). The nickel salt precursor is nickel nitrate. After standing for 24 h, place it in an oven, dry it and then place it in a muffle furnace for calcination (calcination at 800 °C for 4 h) to obtain the NiO / SiO2 precursor.
[0047] Polish the surface oxide layer of the AZ91D magnesium alloy block with sandpaper and then place it in an alumina porcelain boat. Place the Ni / SiO2 precursor powder evenly in another porcelain boat. Place the two porcelain boats parallel in a tube furnace. After evacuating the oxygen in the reaction system by multiple vacuum extractions, introduce high-purity Ar into the tube furnace and heat the tube furnace to 800 °C. The reduction time at this temperature is set to 30 min to prepare the Mg-Ni / SiO2 catalyst.
[0048] Example 3
[0049] Add 2 mL of TEOS to a mixed solution composed of 15 mL of water and 35 mL of isopropanol, and stir at high speed for 5 min. Subsequently, add 1 mL of ammonia water and continue stirring for 2 h. The white solid in the product is obtained by centrifugation and dried at 60 °C for 24 h to obtain monodisperse SiO2 microspheres.
[0050] In the loading process, first measure the water absorption of the SiO2 microspheres, and add a certain amount of nickel salt precursor according to the pre-set Ni content (set here as 10% of the mass of Ni in the NiO / SiO2 precursor). The nickel salt precursor is nickel nitrate. After standing for 24 h, place it in an oven, dry it and then place it in a muffle furnace for calcination (calcination at 800 °C for 4 h) to obtain the NiO / SiO2 precursor.
[0051] Polish the surface oxide layer of the AZ91D magnesium alloy block with sandpaper and then place it in an alumina porcelain boat. Place the Ni / SiO2 precursor powder evenly in another porcelain boat. Place the two porcelain boats parallel in a tube furnace. After evacuating the oxygen in the reaction system by multiple vacuum extractions, introduce high-purity Ar into the tube furnace and heat the tube furnace to 800 °C. The reduction time at this temperature is set to 60 min to prepare the Mg-Ni / SiO2 catalyst.
[0052] Example 4
[0053] Add 2 mL of TEOS to a mixed solution composed of 15 mL of water and 35 mL of isopropanol, and stir at high speed for 5 min. Subsequently, add 1 mL of ammonia water and continue stirring for 2 h. The white solid in the product is obtained by centrifugation and dried at 60 °C for 24 h to obtain monodisperse SiO2 microspheres.
[0054] In the loading process, first measure the water absorption of the SiO2 microspheres, and add a certain amount of nickel salt precursor according to the pre-set Ni content (here set to 10% of the mass of Ni in the NiO / SiO2 precursor), and the nickel salt precursor is nickel nitrate. After standing for 24 h, put it into an oven, dry it and then put it into a muffle furnace for roasting (roast at 800 °C for 4 h) to obtain the NiO / SiO2 precursor.
[0055] Polish the surface oxide layer of the AZ91D magnesium alloy block with sandpaper and then place it in an alumina porcelain boat. Place the Ni / SiO2 precursor powder evenly in another porcelain boat. Place the two porcelain boats parallel in a tube furnace. After evacuating the oxygen in the reaction system by multiple vacuum pumping, introduce high-purity Ar into the tube furnace, and heat the tube furnace to 800 °C. The reduction time at this temperature is set to 120 min to prepare the Mg-Ni / SiO2 catalyst.
[0056] Comparative Example 1
[0057] Add 2 mL of TEOS to a mixed solution composed of 15 mL of water and 35 mL of isopropanol, and stir at high speed for 5 min. Subsequently, add 1 mL of ammonia water and continue stirring for 2 h. The white solid in the product is obtained by centrifugation and dried at 60 °C for 24 h to obtain monodisperse SiO2 microspheres.
[0058] In the loading process, first measure the water absorption of the SiO2 microspheres, and add an appropriate volume of nickel salt precursor according to the water absorption (here set to 10% of the mass of Ni in the NiO / SiO2 precursor), and the nickel salt precursor is nickel nitrate. After standing for 24 h, put it into an oven, dry it and then put it into a muffle furnace for roasting (roast at 800 °C for 4 h) to obtain the NiO / SiO2 catalyst.
[0059] Fill 500 mg of the above-obtained catalyst into the reactor, then introduce a hydrogen-nitrogen mixed gas with a hydrogen volume fraction of 10% into the reactor at a flow rate of 40 mL / min, under normal pressure, heat to the reduction temperature (the reduction temperature is set to 800 °C) and reduce for 2 hours, and then introduce N2 for purging and cool down to room temperature to obtain the Ni / SiO2 catalyst reduced by H2.
[0060] Test Example
[0061] (1) Methane carbon dioxide reforming activity evaluation experiment
[0062] The performance evaluation of methane carbon dioxide reforming reaction was carried out in a fixed-bed quartz tube reactor. Before the reaction, 500 mg of the catalysts prepared in Comparative Example 1 and Examples 1-4 were filled in the reactor, the reaction gas was introduced, the gas before the reaction was analyzed, and the temperature was raised to the reaction temperature (800 °C) and maintained for 100 hours.
[0063] Among them, the reaction gas used was 25% CH4 - 25% CO2 - 50% N2, the gas flow rate was 80 ml / min, the corresponding space velocity was 96000 ml / (g·h), and the reaction pressure was atmospheric pressure. A gas chromatograph (HUAAI) equipped with a hydrogen flame detector (FID) and a thermal conductivity detector (TCD) was used to analyze the gas composition at the reactor outlet, and the concentrations of each component (H2, CO2, CH4, CO, N2) were measured. Samples were taken and measured every 1 hour after reaching the temperature point, and the CO2 conversion rate, CH4 conversion rate, and H2 / CO were calculated using the measured values. The CO2 conversion rate, CH4 conversion rate, and H2 / CO were calculated as follows:
[0064]
[0065]
[0066] Specifically, the CO2 conversion rate, CH4 conversion rate, and H2 / CO at different time lengths are respectively represented by Figure 2 , Figure 3 and Figure 4 . The results show that at the reaction condition of 800 °C, the CO2 conversion rate and CH4 conversion rate of Examples 1-4 are better than those of Comparative Example 1; the CO2 conversion rate and CH4 conversion rate of Example 3 are the best. The stability of the catalyst is also excellent, showing a slight decrease during the 100 h reaction and no deactivation occurred.
[0067] (2) Methane carbon dioxide reforming catalyst characterization
[0068] Thermogravimetric analysis (TGA) characterization
[0069] The weight loss can be attributed to the gasification of carbon, so TGA was carried out to evaluate the exact amount of carbon deposition. The TG characterization of the catalysts in Comparative Example 1 and Examples 1-4 is as Figure 5 shown. In Comparative Example 1, the Ni / SiO2 catalyst reduced by H2 showed obvious coking (about 23.7% wt%), while in contrast, the samples reduced by magnesiothermic reduction in Examples 1-4 had almost no carbon deposition (about 0%). This result strongly indicates that the catalyst prepared by the magnesiothermic reduction method exhibits excellent anti-carbon deposition performance.
[0070] ]Characterization by High-Resolution Transmission Electron Microscopy (HRTEM)
[0071] The HRTEM characterization of the catalysts in Comparative Example 1 and Examples 1-4 after reacting at 800 °C for 100 hours is as Figure 6 shown (as (a) in Figure 6 is the HRTEM characterization of Comparative Example 1, and (b)-(e) are the HRTEM characterizations of Examples 1-4 respectively). Consistent with the thermogravimetric (TG) test results, a large number of carbon nanotubes are piled up on the surface of the Ni / SiO2 catalyst reduced by H2, showing significant coking phenomenon. In contrast, only slight carbon deposition is shown on the surface of the catalyst prepared by magnesiothermic reduction. From this characterization result, the significant improvement in the anti-carbon deposition performance of the catalyst brought by magnesiothermic reduction can be intuitively observed.
[0072] The HRTEM characterization of the catalyst after magnesiothermic reduction in Example 3 is as Figure 7 shown. By measuring the lattice spacing, clear lattice fringes of Ni and MgO can be seen, confirming the successful coating of MgO on the catalyst surface.
[0073] X-ray Diffraction (XRD) Characterization
[0074] The X-ray diffraction (XRD) characterization results of the catalysts in Comparative Example 1 and Examples 1-4 after reduction are as Figure 8 shown. From the XRD spectrum, the diffraction peaks of metallic nickel (Ni 0 ) can be clearly observed, which indicates that during the reaction, magnesium (Mg) successfully reduced nickel oxide (NiO) to metallic nickel.
[0075] The MgO-Ni / SiO2 catalyst prepared in the present invention is obtained by the magnesiothermic reduction method. The optimal CO2 conversion rate of the catalyst prepared in Example 3 at 800 °C is 75.05%, and the CH4 conversion rate is 67.03%; after reacting at 800 °C for 100 h, the CO2 conversion rate decreases by 7.40%, and the CH4 conversion rate decreases by 8.86%; the carbon deposition amount is about 0%.
[0076] Although the embodiments of the present invention have been disclosed as above, it is not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details and the examples shown and described herein.
Claims
1. A preparation method of a highly stable nickel-based catalyst for methane dry reforming, characterized in that, It includes the following steps: Step 1: Load NiO on the SiO2 support to obtain the NiO / SiO2 precursor; Step 2: Place the NiO / SiO2 precursor and the magnesium-based metal in a heating furnace respectively, and introduce an inert gas into the heating furnace; heat the furnace to a temperature at which the magnesium-based metal melts to generate magnesium vapor, and carry out a magnesiothermic reduction reaction on the NiO / SiO2 precursor to obtain a nickel-based methane carbon dioxide reforming catalyst.
2. The preparation method of the highly stable nickel-based methane carbon dioxide reforming catalyst according to claim 1, characterized in that, The SiO2 support is selected from fumed SiO2, mesoporous SiO2 or SiO2 microspheres.
3. The preparation method of the highly stable nickel-based methane carbon dioxide reforming catalyst according to claim 2, characterized in that, In Step 1, the method for loading NiO on the SiO2 support is selected from the impregnation method, the precipitation method or the chemical vapor deposition method.
4. The preparation method of the highly stable nickel-based methane carbon dioxide reforming catalyst according to claim 3, characterized in that, The magnesium-based metal is selected from magnesium or magnesium alloy.
5. The preparation method of the highly stable nickel-based methane carbon dioxide reforming catalyst according to claim 3 or 4, characterized in that, In Step 2, the temperature of the magnesiothermic reduction reaction is 600°C to 1000°C, and the reaction time is 10 min to 2 h.
6. The preparation method of the highly stable nickel-based methane carbon dioxide reforming catalyst according to claim 5, characterized in that, In Step 2, the flow rate of the inert gas introduced is 50 mL / min to 200 mL / min.
7. The preparation method of the highly stable nickel-based methane carbon dioxide reforming catalyst according to claim 6, characterized in that, The inert gas is selected from Ar or He.
8. A highly stable nickel-based catalyst for methane dry reforming, characterized in that, It is prepared by using the preparation method of the highly stable nickel-based methane carbon dioxide reforming catalyst according to any one of claims 1-7.