A Ni-based catalyst suitable for low-temperature catalytic methane steam reaction, a preparation method and application thereof

Abstract

The application discloses a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction and a preparation method and application thereof. The catalyst preparation method is as follows: first, modifying an alumina carrier by using nitrogen-containing organic matters such as urea, melamine or dicyandiamide; then, loading a nickel salt such as nickel nitrate by using an impregnation method; and finally, obtaining the Ni-based catalyst suitable for low-temperature catalytic methane steam reforming reaction after drying and calcination. Compared with an unmodified catalyst, the catalyst has the characteristics of high activity, high carbon deposition resistance and long service life when used for low-temperature methane steam reforming to prepare hydrogen, and has an industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal Ni element catalyst preparation, and particularly relates to a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction and a preparation method and application thereof. BACKGROUND

[0002] With more and more attention paid to global warming, it is imperative to reduce the emission of greenhouse gases in the atmosphere. Carbon dioxide and methane are two common greenhouse gases. In recent years, with the in-depth development of natural gas resources, people have become more and more interested in the conversion of methane. So far, methane is mainly converted into hydrogen or synthesis gas (a mixture of CO and H2) through steam reforming of methane (SRM), dry reforming of methane (DRM) and partial oxidation of methane (POM), and hydrogen is an indispensable green energy for sustainable social development. Synthesis gas can also be synthesized into methanol or other organic compounds through further reaction.

[0003] Among various methane conversion strategies, SRM is the main industrial process for producing hydrogen and synthesis gas. It is an endothermic reaction of methane and steam at high temperature and low pressure. In this process, the water gas shift reaction occurs, further promoting the production of hydrogen.

[0004]

[0005] Nickel-based catalysts are commonly used in traditional SRM processes due to their low cost and high activity. However, carbon deposition and sintering remain the main reasons for the deactivation of traditional Ni-based catalysts. CH4 tends to dissociate on the surface of Ni to form carbon deposition, which covers the active sites of the catalyst, leading to rapid reduction of catalyst activity. Therefore, current research on methane reforming mainly focuses on how to improve the stability of the catalyst. Literature shows that controlling the size of Ni nanoparticles to 3-5 nm or below has better anti-carbon deposition performance. In the development of Ni-based catalysts, preparing small-particle-size and highly dispersed Ni-based catalysts is the key to solving the problem of carbon deposition in industrial production of catalysts (Vogt C, Kranenborg J, Monai M, et al. Structuresensitivity in steam and dry methane reforming over nickel: activity and carbon formation [J]. ACS Catalysis, 2019, 10(2): 1428-1438.). SUMMARY

[0006] The technical problem solved by the present application is that the existing catalyst for low-temperature methane steam reforming process has active centers that are prone to sintering, resulting in catalyst carbon deposition and deactivation. Therefore, the present application provides a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction and a preparation method thereof.

[0007] In order to achieve the above purposes experimentally, the technical solution of the present application is as follows:

[0008] A preparation method of a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction, comprising the following steps.

[0009] 1) An equal volume impregnation method is used to fully dissolve the nitrogen-containing organic matter in the dispersant to obtain an impregnation solution, the carrier alumina is added to the above impregnation solution, ultrasonic treatment is performed for 20-30 minutes, then it is left to stand at room temperature for 12-15 hours, after standing is completed, drying treatment is performed, and then carbonization is performed under a nitrogen atmosphere to obtain modified γ-Al2O3;

[0010] 2) The soluble metal salt of the active component Ni is dissolved in deionized water, and an equal volume impregnation method is used to add it to the modified alumina obtained in step 1), after sufficient impregnation, drying, calcination, tabletting, granulation, screening of 40-60 mesh particles, and reduction, a Ni-based catalyst modified by a nitrogen-containing organic matter is obtained.

[0011] Further, in step 1), the loading amount of the nitrogen-containing organic matter on the carrier alumina is 1%-10%, preferably the loading amount is 3%-5%, and the nitrogen-containing organic matter is urea, dicyanamide or tricyanamide.

[0012] Further, in step 1), the carbonization temperature is 400-800℃, preferably the carbonization temperature is 500-600℃, and the carbonization time is 4-6h.

[0013] Further, in step 2), the soluble metal salt of the active component Ni is a sulfate salt, a nitrate salt or a chloride salt of nickel, and the metal ion concentration of nickel ions in the aqueous solution is 0.5-3.0 mol·L -1 , preferably 1.2-2.0 mol·L -1 .

[0014] Further, in step 2), the calcination temperature is 500-800℃, preferably the calcination temperature is 600-650℃, and the calcination time is 4-6h. Further, in step 2), the reduction atmosphere is hydrogen, the reduction space velocity is 3000-6000h -1 , the reduction temperature is 500-800℃, and the reduction time is 2-5h.

[0015] A Ni-based catalyst suitable for low-temperature catalytic methane steam reaction prepared by the above preparation method.

[0016] The application of a Ni-based catalyst in the low-temperature catalytic steam reforming of methane includes the following steps: a catalytic reaction is carried out in a fixed-bed reactor, the catalyst is packed in the fixed-bed reactor, and a mixture of CH4 and N2 gas is introduced for the catalytic reaction. The ratio of methane gas to nitrogen gas in the mixture is 5:1. At the other end, deionized water is injected into a heating zone using an injection pump for heating and vaporization. The target product of the low-temperature methane steam reforming reaction is hydrogen gas. The reaction temperature is 500–700℃, the reaction pressure is 0.1–5.0 MPa, the water-to-carbon ratio is 2.0–5.0, and the feed gas space velocity is 3000–15000 h⁻¹. -1 .

[0017] The beneficial effects of this invention are as follows:

[0018] 1) By modifying the carrier, the alumina surface is covered with a large amount of carbon nitride, which has an in-situ anchoring effect on the impregnated Ni particles, which is conducive to the formation of small Ni particles, improves the dispersion of Ni on the alumina surface, and thus improves the conversion rate and stability of the catalyst.

[0019] 2) The methane conversion rate of this invention is 55-80%. The catalyst prepared by this method has excellent stability and anti-carbon deposition ability. The preparation process is simple and highly reproducible. Attached Figure Description

[0020] Figure 1 Thermogravimetric analysis of the catalyst after 500 hours of reaction.

[0021] Figure 2 XRD data characterization of the catalyst after re-reduction. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings, but the scope of protection of the present invention is not limited to these embodiments.

[0023] Implementation Case 1

[0024] With a Ni loading of 12%, 0.122 g of urea was fully dissolved in 5 g of deionized water to obtain an impregnation solution for organic matter; then 5 g of γ-Al2O3 was added to the above impregnation solution, sonicated for 20 minutes, and then placed at room temperature for 12 h. After standing, it was dried at 80 °C for 6 h, and then carbonized under a nitrogen atmosphere at a carbonization temperature of 450 °C for 4 h to obtain the modified γ-Al2O3. 3.35g of Ni(NO3)2·6H2O was then fully dissolved in 5g of deionized water to obtain an impregnation solution containing the active component. The modified γ-Al2O3 was then added to the impregnation solution containing the active component, and impregnation was allowed to complete. Afterward, the mixture was allowed to stand at room temperature for 12 hours, then dried at 80℃ for 6 hours. Following this, calcination was carried out under a nitrogen atmosphere at 600℃ for 4 hours. The resulting tablets were then granulated, screened to 40-60 mesh, and placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0025] Comparison Case 1

[0026] With a Ni loading of 12%, γ-Al₂O₃ was left unmodified: 3.35g Ni(NO₃)₂·6H₂O was fully dissolved in 5g deionized water to obtain an impregnation solution containing the active component. Unmodified γ-Al₂O₃ was added to the impregnation solution containing the active component, and after ultrasonication for 20 minutes, it was allowed to stand at room temperature for 12 hours. After standing, it was dried at 80℃ for 6 hours, followed by calcination at 600℃ for 4 hours under a nitrogen atmosphere. The calcined particles were then tableted, granulated, and screened to 40-60 mesh. The tablets were then placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0027] Comparison Case 2

[0028] With a Ni loading of 12%, a co-impregnation method was adopted: 3.35g Ni(NO3)2·6H2O and 0.122g urea were dissolved together in 5g deionized water to obtain an impregnation solution containing the active component. Unmodified γ-Al2O3 was added to the impregnation solution containing the active component, and after ultrasonication for 20 minutes, the impregnation was allowed to complete. Afterward, the mixture was allowed to stand at room temperature for 12 hours, followed by drying at 80℃ for 6 hours. Then, calcination was carried out under a nitrogen atmosphere at 600℃ for 4 hours. The resulting tablets were then granulated, screened to 40-60 mesh, and placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0029] Implementation Case 2

[0030] With a Ni loading of 12%, the amount of nitrogen-containing organic matter was varied: 0.251 g of urea was fully dissolved in 5 g of deionized water to obtain an impregnation solution for the organic matter; then 5 g of γ-Al2O3 was added to the above impregnation solution, ultrasonicated for 20 minutes, and allowed to impregnate completely. Then, it was allowed to stand at room temperature for 12 h, and after standing, it was dried at 80 °C for 6 h. After that, carbonization was carried out under a nitrogen atmosphere at a carbonization temperature of 450 °C for 4 h to obtain the modified γ-Al2O3. 3.35g of Ni(NO3)2·6H2O was then fully dissolved in 5g of deionized water to obtain an impregnation solution containing the active component. The modified γ-Al2O3 was then added to the impregnation solution containing the active component, and impregnation was allowed to complete. Afterward, the mixture was allowed to stand at room temperature for 12 hours, then dried at 80℃ for 6 hours. Following this, calcination was carried out under a nitrogen atmosphere at 600℃ for 4 hours. The resulting tablets were then granulated, screened to 40-60 mesh, and placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0031] Implementation Case 3

[0032] With a Ni loading of 12%, the amount of nitrogen-containing organic matter was changed: 0.502 g of urea was fully dissolved in 5 g of deionized water to obtain an impregnation solution for the organic matter; then 5 g of γ-Al2O3 was added to the above impregnation solution, ultrasonicated for 20 minutes, and allowed to impregnate completely. Then, it was allowed to stand at room temperature for 12 h, and after standing, it was dried at 80 °C for 6 h. Then, carbonization was carried out under a nitrogen atmosphere at a carbonization temperature of 450 °C for 4 h to obtain the modified γ-Al2O3. 3.35g of Ni(NO3)2·6H2O was then fully dissolved in 5g of deionized water to obtain an impregnation solution containing the active component. The modified γ-Al2O3 was then added to the impregnation solution containing the active component, and impregnation was allowed to complete. Afterward, the mixture was allowed to stand at room temperature for 12 hours, then dried at 80℃ for 6 hours. Following this, calcination was carried out in air at 600℃ for 4 hours. The resulting tablets were then granulated, screened to 40-60 mesh, and placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0033] Implementation Case 4

[0034] With a Ni loading of 12%, the type of nitrogen-containing organic matter was changed: 0.144 g of melamine was fully dissolved in 5 g of deionized water to obtain an impregnation solution for the organic matter; then 5 g of γ-Al2O3 was added to the above impregnation solution and sonicated for 20 minutes. After the impregnation was complete, it was allowed to stand at room temperature for 12 h. After standing, it was dried at 80 °C for 6 h. Then, carbonization was carried out under a nitrogen atmosphere at a carbonization temperature of 450 °C for 4 h to obtain the modified γ-Al2O3. 3.35g of Ni(NO3)2·6H2O was then fully dissolved in 5g of deionized water to obtain an impregnation solution containing the active component. The modified γ-Al2O3 was then added to the impregnation solution containing the active component, and impregnation was allowed to complete. Afterward, the mixture was allowed to stand at room temperature for 12 hours, then dried at 80℃ for 6 hours. Following this, calcination was carried out in air at 600℃ for 4 hours. The resulting tablets were then granulated, screened to 40-60 mesh, and placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0035] Implementation Case 5

[0036] With a Ni loading of 12%, the type of nitrogen-containing organic compound was changed: 0.164 g of melamine was fully dissolved in 5 g of deionized water to obtain an impregnation solution for the organic compound; then 5 g of γ-Al2O3 was added to the above impregnation solution, ultrasonicated for 20 minutes, and allowed to impregnate completely. Then, it was allowed to stand at room temperature for 12 h, and after standing, it was dried at 80 °C for 6 h. Then, carbonization was carried out under a nitrogen atmosphere at a carbonization temperature of 450 °C for 4 h to obtain the modified γ-Al2O3. 3.35g of Ni(NO3)2·6H2O was then fully dissolved in 5g of deionized water to obtain an impregnation solution containing the active component. The modified γ-Al2O3 was then added to the impregnation solution containing the active component, and impregnation was allowed to complete. Afterward, the mixture was allowed to stand at room temperature for 12 hours, then dried at 80℃ for 6 hours. Following this, calcination was carried out in air at 600℃ for 4 hours. The resulting tablets were then granulated, screened to 40-60 mesh, and placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0037] Implementation Case Six

[0038] With a Ni loading of 12%, the carbonization temperature was changed: 0.122g of urea was fully dissolved in 5g of deionized water to obtain an impregnation solution for organic matter; then 5g of γ-Al2O3 was added to the above impregnation solution, ultrasonicated for 20 minutes, and allowed to impregnate completely. Then, it was allowed to stand at room temperature for 12 hours, and after standing, it was dried at 80℃ for 6 hours. Then, carbonization was carried out under a nitrogen atmosphere at a carbonization temperature of 500℃ for 4 hours to obtain the modified γ-Al2O3. 3.35g of Ni(NO3)2·6H2O was then fully dissolved in 5g of deionized water to obtain an impregnation solution containing the active component. The modified γ-Al2O3 was then added to the impregnation solution containing the active component, and impregnation was allowed to complete. Afterward, the mixture was allowed to stand at room temperature for 12 hours, then dried at 80℃ for 6 hours. Following this, calcination was carried out in an air atmosphere at 600℃ for 4 hours. The resulting tablets were then granulated, screened to 40-60 mesh, and placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0039] Implementation Case Seven

[0040] With a Ni loading of 12%, the carbonization atmosphere was changed: 0.122g of urea was fully dissolved in 5g of deionized water to obtain an impregnation solution for organic matter; then 5g of γ-Al2O3 was added to the above impregnation solution, ultrasonicated for 20 minutes, and allowed to impregnate completely. Then, it was allowed to stand at room temperature for 12 hours, and after standing, it was dried at 80℃ for 6 hours. Then, carbonization was carried out under an argon atmosphere at a carbonization temperature of 450℃ for 4 hours to obtain the modified γ-Al2O3. 3.35g of Ni(NO3)2·6H2O was then fully dissolved in 5g of deionized water to obtain an impregnation solution containing the active component. The modified γ-Al2O3 was then added to the impregnation solution containing the active component, and impregnation was allowed to complete. Afterward, the mixture was allowed to stand at room temperature for 12 hours, then dried at 80℃ for 6 hours. Following this, calcination was carried out in air at 600℃ for 4 hours. The resulting tablets were then granulated, screened to 40-60 mesh, and placed in a fixed-bed reactor for in-situ reduction at 600℃ for 4000 hours. -1 At a space velocity of 1000 m / s, a reduction with hydrogen was performed for 2 h to obtain a nitrogen-based catalyst modified with nitrogen-containing organic matter.

[0041] To verify the beneficial effects of the present invention, the inventors evaluated the performance of the low-temperature methane steam reforming reaction in Examples 1-7 and Comparative Examples 1 and 2. The specific experimental results are as follows:

[0042] 1 ml (0.7 g) of catalyst was placed in the isothermal zone of a fixed-bed reactor. A mixture of methane and nitrogen (volume ratio of methane to nitrogen 5:1) was introduced under atmospheric pressure. Water vapor was obtained at the other end using an injection pump. The reaction temperature was 600 °C, the reaction pressure was atmospheric pressure, and the reaction space velocity was 9600 h⁻¹. -1 The water-to-carbon ratio was 4. Nitrogen was used as an internal standard for chromatographic analysis. The methane, carbon monoxide, and carbon dioxide in the gaseous products were quantitatively analyzed by online chromatography equipped with a TCD. The methane conversion rate was calculated, and the test results are listed in Table 1.

[0043] Table 1 Summary of activity evaluation data for methane steam reforming reaction with different catalysts

[0044]

[0045]

[0046] Table 1 shows that the conversion rates differ across cases. In Case 1, the initial conversion rate was 59.17%, but after 500 hours of reaction, the methane conversion rate decreased to 54.21%. In Case 2, the initial conversion rate was 65.81%, but after 500 hours of reaction, the methane conversion rate decreased to 42.74%. Comparatively, Case 2, due to the addition of nitrogen-containing organic matter via co-impregnation, showed a certain improvement in conversion rate, indicating that nitrogen-containing organic matter has a certain effect on catalyst modification. In Case 1, the initial conversion rate was 68.81%, but after 500 hours of reaction, the methane conversion rate decreased to 65.22%. Compared to Case 2, where the methane conversion rate was further improved, this invention exhibits a higher methane conversion rate. This invention further enhances catalytic activity by changing the order of organic matter addition during impregnation. A possible reason is that pre-impregnation with carbonized organic matter facilitates the uniform dispersion of carbon species on the surface, forming more abundant carbide defects, which further enhance catalytic activity.

[0047] Implementation cases 1, 2, and 3 are single-factor variable experiments involving nitrogen-containing organic compounds. When the nitrogen content is 1 wt%, 2 wt%, and 4 wt%, the corresponding methane conversion rates are 68.81%, 71.23%, and 64.73%, respectively. It is easy to observe that as the amount of nitrogen-containing organic compound doping increases, the methane conversion rate shows a trend of first increasing and then decreasing. A possible reason is that with the increase of nitrogen-containing organic compounds, the interaction between the organic compound and the active component is enhanced, leading to an increase in methane conversion rate. However, when the organic content is excessively increased, excess nitrogenous substances may poison the surface of some metal particles, thereby reducing the number of active sites and decreasing activity. Implementation cases 1, 4, and 5 are experiments on the types of nitrogen-containing organic compounds used for impregnation. The conversion rates differ when different nitrogen-containing organic compounds are selected for impregnation. Current experimental data suggests that urea impregnation provides the best methane conversion performance, which may be related to the molecular structure of urea.

[0048] like Figure 1As shown, the catalyst was collected after the reaction and subjected to thermogravimetric analysis. The horizontal axis represents temperature, and the vertical axis represents mass percentage. The graph shows that all four curves exhibit a mass loss of approximately 2% from 0 to 200℃, presumably due to moisture adsorbed on the catalyst surface and impurities from the air. The mass increase observed between 200 and 400℃ can be attributed to the oxidation of nickel. A significant mass loss begins at 450℃, caused by the combustion reaction of carbon deposits on the catalyst surface. By calculating the mass difference between the catalyst at room temperature and at 800℃, the carbon deposition on the catalyst during that reaction time can be inferred. A smaller mass difference indicates less carbon buildup on the catalyst surface and stronger resistance to carbon deposition. The graph shows that in Example 1, the carbon deposition after 500 hours of reaction was only 14.68%, far less than the 21.89% in Comparative Example 1, demonstrating that this invention improves the catalyst's resistance to carbon deposition.

[0049] Figure 2 The XRD patterns of the catalysts from different cases are shown. All four catalysts exhibit distinct characteristic diffraction peaks for Ni. The average size of the Ni grains can be estimated using the Scherrer formula. As shown in the figure, the peak with 2θ at 43° represents Ni. Compared to the characteristic peak in Comparative Case 1, the characteristic peak in Case 1 is flatter and has a larger full width at half maximum (FWHM). Based on the formula, it can be deduced that Case 1 has smaller Ni particles. Therefore, it is easy to conclude that after modification of alumina with nitrogen-containing organic compounds, it is beneficial to form small Ni particles on the surface, which, under the premise of the same surface area, is conducive to improving dispersion. Simultaneously, smaller active component particles often expose more active sites, which is beneficial to improving catalytic activity. Therefore, this invention provides a catalyst with high dispersion, high activity, and excellent anti-carbon deposition properties, as well as its preparation method.

Claims

1. A method for preparing a Ni-based catalyst suitable for low-temperature catalytic reaction of methane with steam, characterized in that, Includes the following steps: 1) Using the equal volume impregnation method, nitrogen-containing organic matter is fully dissolved in the dispersant to obtain an impregnation solution. The carrier alumina is added to the above impregnation solution, ultrasonicated for 20-30 minutes, and then left to stand at room temperature for 12-15 hours. After standing, it is dried and then carbonized under a nitrogen atmosphere to obtain modified γ-Al2O3. 2) Dissolve the soluble metal salt of the active component Ni in deionized water and add it dropwise to the modified alumina obtained in step 1) by impregnation with equal volume. After thorough impregnation, dry, calcine, press, granulate, screen 40-60 mesh particles, and reduce to obtain a Ni-based catalyst modified with nitrogen-containing organic matter. The loading of nitrogen-containing organic matter on the carrier alumina is 1%-10%, and the nitrogen-containing organic matter is urea, melamine or melamine.

2. The method for preparing a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction as described in claim 1, characterized in that, In step 1), the loading of nitrogen-containing organic matter on the alumina support is 3%-5%.

3. The method for preparing a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction as described in claim 1, characterized in that, In step 1), the carbonization temperature is 400-800℃ and the carbonization time is 4-6h.

4. The method for preparing a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction as described in claim 3, characterized in that, In step 1), the carbonization temperature is 500-600℃.

5. The method for preparing a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction as described in claim 1, characterized in that, In step 2), the soluble metal salt of the active component Ni is a nickel sulfate, nitrate, or chloride salt, and the concentration of nickel ions in the aqueous solution is 0.5-3.0 mol·L⁻¹. -1 .

6. A method for preparing a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction as described in claim 5, characterized in that, In step 2), the concentration of nickel ions in the aqueous solution is 1.2-2.0 mol·L⁻¹. -1 .

7. The method for preparing a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction as described in claim 1, characterized in that, In step 2), the roasting temperature is 500-800℃ and the roasting time is 4-6h.

8. The method for preparing a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction as described in claim 1, characterized in that, In step 2), the roasting temperature is 600-650℃.

9. The method for preparing a Ni-based catalyst suitable for low-temperature catalytic methane steam reaction as described in claim 1, characterized in that... In step 2), the reducing atmosphere is hydrogen, and the reducing space velocity is 3000-6000 h⁻¹. -1 The reduction temperature is 500-800℃, and the reduction time is 2-5h.

10. A Ni-based catalyst suitable for low-temperature catalytic reaction of methane with steam, prepared by any one of the preparation methods described in claims 1-9.

11. The application of the Ni-based catalyst as described in claim 10 in the low-temperature catalytic reaction of methane with steam, characterized in that, The process includes the following steps: a catalytic reaction is carried out in a fixed-bed reactor, with the catalyst loaded in the reactor. A mixture of CH4 and N2 gas is introduced for the catalytic reaction, with a methane to nitrogen ratio of 5:

1. At the other end, deionized water is injected into a heating zone via an injection pump for heating and vaporization. The target product of the low-temperature methane steam reforming reaction is hydrogen. The reaction temperature is 500–700 °C, the reaction pressure is 0.1–5.0 MPa, the water-to-carbon ratio is 2.0–5.0, and the feed gas space velocity is 3000–15000 h⁻¹. -1 .

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