Application of a Ni / NiAl2O4-rGO catalyst in low-temperature selective methanation of CO

Abstract

This invention discloses the application of a Ni / NiAl2O4-rGO catalyst in the low-temperature selective methanation of CO. The invention utilizes a modified co-precipitation method to generate aluminate-intercalated nickel-aluminum layered double hydroxide (NiALO) on the surface of graphene oxide (GO). This NiALO is then calcined to construct a large specific surface area NiALO spinel-reduced graphene oxide (NiAl2O4-rGO) composite support. The active component, nickel, is then loaded using an impregnation method, followed by calcination and reduction to prepare the Ni / NiAl2O4-rGO catalyst. The catalyst of this invention exhibits good thermal conductivity, large specific surface area, and high dispersion of the active metal. For the selective methanation of carbon monoxide in hydrogen-rich gas, the catalyst of this invention demonstrates low reaction temperature, high activity and selectivity, and good stability. The catalyst preparation method of this invention is simple, requires a low calcination temperature, and is easy to promote.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to the application of a Ni / NiAl2O4-rGO catalyst in the low-temperature selective methanation of CO. This catalyst can reduce the concentration of CO in hydrogen-rich gas to below 10 ppm at a lower temperature, thereby meeting the demand for high-quality hydrogen fuel in proton exchange membrane fuel cells. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) offer advantages such as high efficiency, low pollution, low operating temperature, and high power density, making them a promising new power source to replace internal combustion engines. Hydrogen, used as fuel in PEMFCs, primarily originates from the reforming reactions of hydrocarbons such as methanol, ethanol, and methane. Even small amounts of CO in the reformed hydrogen-rich gas can poison and deactivate the Pt / C catalyst in PEMFCs, severely impacting battery performance. Therefore, it is essential to employ technical methods to remove CO from the hydrogen-rich gas.

[0003] Chemical methods for CO removal from hydrogen-rich gases mainly include CO preferential oxidation and CO selective methanation. Compared with CO preferential oxidation, CO selective methanation does not require the addition of additional reactants and can directly utilize H2 from the hydrogen-rich gas. The generated CH4 is harmless to proton exchange membrane fuel cells, and therefore it is considered one of the most effective methods for deep CO removal. Developing a CO methanation catalyst with good low-temperature activity and high selectivity is the main challenge.

[0004] In recent years, spinel has been widely used in Fischer-Tropsch synthesis reactions due to its good stability, strong tolerance, and ability to effectively inhibit carbon deposition. Using spinel as a support to load active metals has also yielded good results in CO methanation reactions. Wang Shengjia et al. synthesized spinel with a specific surface area as high as 235.8 m² using carbon black as a hard template and a modified co-precipitation method at 800℃. 2 ·g -1 MgAl2O4 was used to prepare a Ni / MgAl2O4 catalyst. At a reaction temperature of 350℃, the CO conversion rate was close to 100%, and the selectivity was as high as 85%. Simultaneously, this catalyst effectively improved the thermal stability and anti-coking ability of the catalyst (Facile preparation of a Ni / MgAl2O4 catalyst with high surface area:enhancement in activity and stability for CO methanation. Main Group Metal Chemistry 2018, 41(3-4):73-89). Yan Xiaoliang et al. used MIL-53 as a template and calcined it at 900℃ to prepare a catalyst with a specific surface area of ​​144 m². 2·g -1 Ni / NiAl2O4 catalysts were prepared by supporting Ni on a NiAl2O4 support. At 350℃, the CO conversion reached 100%, with a selectivity approaching 60% (ANi-based catalyst with enhanced Ni-support interaction for highly efficient CO methanation. Catalysis Science).

[0005] Technology 2018, 8(14), 3474-3483). Dong Xinfa et al. synthesized a specific surface area of ​​up to 247 m² using propylene oxide as a chelating agent at 700℃ via a sol-gel method. 2 ·g -1 A Ni-ZrO2 / NiAl2O4 catalyst was prepared by impregnation and reduction on a nickel-rich NiAl2O4 support, which can reduce the CO concentration in hydrogen-rich gas to below 10 ppm at 190 °C (CN110479280B). C. Quilner et al. prepared a catalyst with a specific surface area of ​​58 m² using Ni-Al-LDH and Ni(NO3)2 as precursors by first calcining at a low temperature of 425 °C and then at a high temperature of 850 °C. 2 ·g -1 The NiAl2O4 support obtained by this method allows the Ni / NiAl2O4 to maintain a 93% CO conversion rate at 600℃, which remains essentially unchanged over 480 h (CN104039452B). Zhang Gengrui et al. synthesized a Ni / NiAl2O4 with a specific surface area of ​​68 m² using a hydrothermal method. 2 ·g -1 The Ni / ZnAl2O4 catalyst prepared using ZnAl2O4 as a support has a CO conversion rate of over 90% and a CH4 selectivity of approximately 83% at 500℃ (High-Stability ZnAl2O4Spinel-Supported NickelCatalyst for High-Temperature Syngas Methanation. Industrial & Engineering Chemistry Research 2023, 62(41), 16668-16675).

[0006] Existing methods for synthesizing spinel supports generally suffer from either excessively high calcination temperatures or small specific surface areas (<100m²). 2 ·g -1Ni-based catalysts suffer from several drawbacks, including the high temperatures required for CO selective methanation catalysts prepared from spinel-supported active metals, leading to increased competition for methanation with CO and a decrease in CO selectivity. Furthermore, CO methanation is an exothermic reaction, and spinel has poor thermal conductivity; unremoved heat during the reaction can cause aggregation and sintering of the Ni-based catalyst, resulting in decreased catalyst activity and stability. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a Ni / NiAl2O4-rGO catalyst and its application in the low-temperature selective methanation of CO. This invention utilizes an improved co-precipitation method to generate [the catalyst] on the surface of graphene oxide (GO). Intercalated nickel-aluminum hydrotalcite was calcined to prepare NiAl2O4-rGO composite support material, then loaded with the active component Ni, and reduced to prepare Ni / NiAl2O4-rGO catalyst. The prepared catalyst exhibited excellent low-temperature activity for selective CO methanation.

[0008] The objective of this invention is achieved through the following technical solution.

[0009] A Ni / NiAl2O4-rGO catalyst and its application in the low-temperature selective methanation of CO. The catalyst is used for the deep removal of CO from hydrogen-rich gas. The catalyst is a metal-supported catalyst with Ni as the active component and nickel-aluminum spinel-reduced graphene oxide (NiAl2O4-rGO) composite material as the support.

[0010] The method for preparing the catalyst includes the following steps:

[0011] (1) Preparation of NiAl2O4-rGO composite support

[0012] NiCl2·6H2O and AlCl3 were dissolved in water and denoted as solution A; NaOH and NaAlO2 were dissolved in water and denoted as solution B; NaAlO2 and GO were dissolved in water to form a suspension and denoted as C; solutions A and B were added dropwise to suspension C simultaneously and at the same rate under an inert gas atmosphere and at a certain temperature. After the addition was completed, the pH value was adjusted, and the mixture was stirred, aged, filtered, washed, dried, and calcined under argon conditions to obtain the NiAl2O4-rGO support.

[0013] (2) Preparation of Ni / NiAl2O4-rGO catalyst

[0014] The NiAl2O4-rGO support was impregnated in anhydrous ethanol containing Ni(NO3)2·6H2O, and then dried, calcined under an inert gas atmosphere, and reduced to obtain the Ni / NiAl2O4-rGO catalyst.

[0015] Preferably, in step (1), the total nickel-aluminum molar ratio Ni:Al in solutions A, B, and C is 0.4 to 0.6:1, more preferably 0.5:1;

[0016] In step (1), the mass ratio of NiAl2O4 to GO in the support is 30 to 60:1, more preferably 50:1;

[0017] In step (1), the coprecipitation reaction temperature is controlled at 60-90℃, more preferably 80℃;

[0018] In step (1), the pH is controlled between 9.0 and 11.0, more preferably 10;

[0019] In step (1), the roasting temperature is 400-600℃, more preferably 500℃.

[0020] Preferably, in step (2), the loading of Ni catalyst is 10.0 to 40.0 wt%, more preferably 30 wt%;

[0021] In step (2), the impregnation and stirring time is 12 to 48 hours, more preferably 24 hours;

[0022] In step (2), the calcination temperature is 400-500℃, more preferably 450℃;

[0023] In step (2), the reduction temperature is 450-600℃, more preferably 500℃.

[0024] Preferably, in steps (1) and (2), the inert gas is nitrogen or argon.

[0025] Preferably, the concentration of CO in the hydrogen-rich gas is 0.5–2.0 vol%, the temperature for low-temperature selective methanation of CO is 185–240 °C, and the space velocity is 4500–7500 ml·h. -1 ·g -1 .

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The CO low-temperature selective methanation Ni / NiAl2O4-rGO catalyst of the present invention has excellent CO low-temperature methanation activity. It can reduce the CO concentration in hydrogen-rich gas to below 10ppm in a low reaction temperature range (185~240℃) and the selectivity is higher than 50%. It can be applied to the deep purification of hydrogen-rich fuel gas in proton exchange membrane fuel cells and meet the requirements of fuel cells for high-quality hydrogen fuel.

[0028] (2) The catalyst of the present invention does not use precious metals and is inexpensive.

[0029] (3) This invention employs an improved co-precipitation method to generate graphene oxide (GO) on the surface. Intercalated nickel-aluminum hydrotalcite was calcined to prepare a NiAl2O4-rGO composite carrier material with good thermal conductivity and stability.

[0030] (4) The Ni / NiAl2O4-rGO catalyst has a simple preparation method, low calcination temperature, low energy consumption, and is easy to promote. Attached Figure Description

[0031] Figure 1 This is the XRD pattern of NiAl2O4-rGO.

[0032] Figure 2a and Figure 2b The graphs show the changes in CO and CH4 concentrations with temperature during the CO selective methanation reaction in Examples 1-3.

[0033] Figure 3a and Figure 3b This is an activity diagram of the CO selective methanation reaction in Example 2, Comparative Example 1, and Comparative Example 2.

[0034] Figure 4a and Figure 4b The graphs show the changes in CO and CH4 concentrations with temperature during the CO selective methanation reaction in Examples 2 and Comparative Example 2. Detailed Implementation

[0035] The specific implementation of the present invention will be further described below with reference to examples and accompanying drawings, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0036] Catalyst performance testing in the examples: The catalyst was pressed into tablets and sieved. 0.2g of 40-60 mesh catalyst was selected and placed in a quartz reaction tube with an inner diameter of 6mm. A mixed gas containing 1.01% CO, 20.5% CO2 and 78.49% H2 was introduced at a space velocity of 6000ml·h. -1 ·g -1 The selective methanation activity and selectivity of the catalyst for CO were tested within the reaction temperature range of 150–320 °C, and the reaction products were detected online by gas chromatography after drying.

[0037] Example 1

[0038] (1) Preparation of NiAl2O4-rGO support: 6.727 g of NiCl2·6H2O and 1.889 g of AlCl3 were dissolved in 50 ml of deionized water and stirred at room temperature for 30 min, and this solution was recorded as solution A. 1.8868 g of NaOH and 1.1742 g of NaAlO2 were dissolved in 50 ml of deionized water and stirred at room temperature for 30 min, and this solution was recorded as solution B. 2.348 g of NaAlO2 and 0.1 g of GO were weighed in 50 ml of deionized water and sonicated at room temperature for 30 min, and this suspension was recorded as suspension C. Suspension C was transferred to a three-necked flask in a constant temperature water bath at 80 °C. Under a N2 protective atmosphere, solutions A and B were slowly added dropwise to the three-necked flask simultaneously. After completion, 0.1 mol·L⁻¹ of GO was added dropwise. -1 Add NaOH to the solution until the pH reaches 10, and stir for 20 min. Then wash and filter until the pH reaches 7. The resulting filter cake is dried for 24 h and then heated in a tube furnace under argon protection at 5 °C / min. -1 The temperature was increased to 500℃ at a rising rate, and then calcined at a constant temperature for 3 hours. The resulting powder is the catalyst composite support NiAl2O4-rGO. Figure 1 Table 1 shows the XRD test results of the composite support and the nitrogen adsorption-desorption test results.

[0039] Table 1

[0040]

[0041] (2) Preparation of Ni / NiAl2O4-rGO catalyst: Take 0.4954g Ni(NO3)2·6H2O in a beaker, add 10ml anhydrous ethanol, stir until completely dissolved, take 1.0g NiAl2O4-rGO composite support and impregnate it in the above solution, stir at room temperature for 24h, slowly evaporate to dryness in a water bath at 60℃, dry at 120℃ for 12h, then calcine in a tube furnace under argon protection at 450℃ for 1.5h, and reduce at 500℃ for 1.5h in a mixed gas atmosphere of H2 and N2 containing 50vol% H2 to obtain Ni / NiAl2O4-rGO catalyst, denoted as 10Ni / NiAl2O4-rGO, where the Ni loading is 10.0wt%.

[0042] The catalyst performance test results show (see) Figure 2a and Figure 2b The catalyst prepared in this embodiment can reduce the CO concentration in the outlet gas to below 10 ppm in the temperature range of 200-260°C, while keeping the CH4 concentration below 2.0% and the selectivity greater than 50%.

[0043] Example 2

[0044] (1) The preparation of NiAl2O4-rGO composite support is the same as in Example 1.

[0045] (2) Preparation of Ni / NiAl2O4-rGO catalyst: 1.4865g Ni(NO3)2·6H2O was placed in a beaker, 10ml of anhydrous ethanol was added, and the mixture was stirred until completely dissolved. 1.0g NiAl2O4-rGO composite support was impregnated in the above solution, stirred at room temperature for 24h, slowly evaporated to dryness in a water bath at 60℃, dried at 120℃ for 12h, then calcined in a tube furnace under argon protection at 450℃ for 1.5h, and reduced at 500℃ for 1.5h in a mixed gas atmosphere of H2 and N2 containing 50vol% H2 to obtain Ni / NiAl2O4-rGO catalyst, denoted as 30Ni / NiAl2O4-rGO, wherein the Ni loading is 30.0wt%.

[0046] The catalyst performance test results show (see) Figure 2a and 2b The catalyst prepared in this embodiment can reduce the CO concentration in the outlet gas to below 10 ppm while keeping the CH4 concentration below 2.0% in the temperature range of 185 to 240°C, i.e., the selectivity is greater than 50%.

[0047] Example 3

[0048] (1) The preparation of NiAl2O4-rGO composite support is the same as in Example 1.

[0049] (2) Preparation of Ni / NiAl2O4-rGO catalyst: 1.9815g Ni(NO3)2·6H2O was placed in a beaker, 10ml of anhydrous ethanol was added, and the mixture was stirred until completely dissolved. 1.0g NiAl2O4-rGO support was impregnated in the above solution, stirred at room temperature for 24h, slowly evaporated to dryness in a water bath at 60℃, dried at 120℃ for 12h, calcined in a tube furnace under argon protection at 450℃ for 1.5h, and reduced at 500℃ for 1.5h in a mixed gas atmosphere of H2 and N2 containing 50vol% H2 to obtain Ni / NiAl2O4-rGO catalyst, denoted as 40Ni / NiAl2O4-rGO, wherein the Ni loading is 40.0wt%.

[0050] The catalyst performance test results show (see) Figure 2a and 2b The catalyst prepared in this embodiment can reduce the CO concentration in the outlet gas to below 10 ppm in the temperature range of 190 to 240°C, while keeping the CH4 concentration below 2.0%, i.e., the selectivity is greater than 50%.

[0051] Comparative Example 1

[0052] (1) Preparation of NiAl2O4 support: 6.727 g of NiCl2·6H2O and 1.889 g of AlCl3 were dissolved in 50 ml of deionized water and stirred at room temperature for 30 min, and this solution was recorded as solution A. 1.8868 g of NaOH and 1.1742 g of NaAlO2 were dissolved in 50 ml of deionized water and stirred at room temperature for 30 min, and this solution was recorded as solution B. 2.348 g of NaAlO2 was dissolved in 50 ml of deionized water and stirred at room temperature for 30 min, and this solution was recorded as solution C. Solution C was poured into a three-necked flask in a water bath, and the temperature was controlled at 80 °C. Under a N2 protective atmosphere, solutions A and B were slowly added dropwise to the three-necked flask simultaneously, and then 0.1 mol·L⁻¹ was added dropwise. -1 Add NaOH until the pH of the solution reaches 10, and stir for 20 min. Then wash and filter until the pH of the solution reaches 7. The resulting filter cake is dried at 100 °C for 24 h, and then in a tube furnace under Ar atmosphere at 5 °C / min. -1 The temperature was increased to 500℃ at a heating rate and calcined at a constant temperature for 3 hours. The resulting powder was the catalyst support NiAl2O4. Nitrogen adsorption-desorption experiments were performed on the prepared NiAl2O4, and the results are shown in Table 1.

[0053] (2) Preparation of Ni / NiAl2O4 catalyst: 1.4865g Ni(NO3)2·6H2O was placed in a beaker, 10ml of anhydrous ethanol was added, and the mixture was stirred until completely dissolved. 1.0g NiAl2O4 support was impregnated in the above solution, stirred at room temperature for 24h, slowly evaporated to dryness in a water bath at 60℃, dried at 120℃ for 12h, calcined in a tube furnace under argon protection at 450℃ for 1.5h, and reduced at 500℃ for 1.5h in a mixed gas atmosphere of H2 and N2 containing 50vol% H2 to obtain the Ni / NiAl2O4 catalyst, denoted as 30Ni / NiAl2O4, wherein the Ni loading is 30.0wt%.

[0054] The catalyst performance test results show (see) Figure 3a and Figure 3b The catalyst prepared in this comparative example can reduce the CO concentration in the outlet gas to below 10 ppm in the temperature range of 240-245℃, while keeping the CH4 concentration below 2.0%, i.e., the selectivity is greater than 50%.

[0055] Comparative Example 2

[0056] (1) The preparation of NiAl2O4-rGO composite support is the same as in Example 1.

[0057] (2) Preparation of Ni / NiAl2O4-rGO catalyst: 1.4865g Ni(NO3)2·6H2O was placed in a beaker, 10ml of anhydrous ethanol was added, and the mixture was stirred until completely dissolved. 1.0g NiAl2O4-rGO composite support was impregnated in the above solution, stirred at room temperature for 24h, slowly evaporated to dryness in a water bath at 60℃, dried at 120℃ for 12h, then calcined in a tube furnace under argon protection at 450℃ for 1.5h, and reduced at 400℃ for 1.5h in a mixed gas atmosphere of H2 and N2 containing 50vol% H2 to obtain Ni / NiAl2O4-rGO catalyst, denoted as 30Ni / NiAl2O4-rGO-400, wherein the Ni loading is 30.0wt%.

[0058] The catalyst performance test results show (see) Figure 4a and 4b The catalyst prepared in this comparative example can reduce the CO concentration in the outlet gas to below 10 ppm in the temperature range of 210–260 °C, while keeping the CH4 concentration below 2.0%, i.e., the selectivity is greater than 50%.

[0059] Comparative Example 3

[0060] (1) Preparation of NiAl2O4-rGO-M support: 6.727 g of NiCl2·6H2O and 1.889 g of AlCl3 were dissolved in 50 ml of deionized water and stirred at room temperature for 30 min, and this solution was recorded as solution A. 1.8868 g of NaOH and 1.1742 g of NaAlO2 were dissolved in 50 ml of deionized water and stirred at room temperature for 30 min, and this solution was recorded as solution B. 2.348 g of NaAlO2 were dissolved in 50 ml of deionized water and stirred at room temperature for 30 min, and this solution was recorded as solution C. Solution C was transferred to a three-necked flask in a water bath, and the temperature was controlled at 80 °C. Under a N2 protective atmosphere, solutions A and B were slowly added dropwise to the three-necked flask simultaneously, and then 0.1 mol·L⁻¹ was added dropwise. -1 Add NaOH to the solution until the pH reaches 10, stir for 20 min, then wash and filter until the pH reaches 7. Dry the resulting filter cake at 100℃ for 24 h to obtain Ni-Al-LDH. Add 0.1 g GO to the prepared Ni-Al-LDH, mix thoroughly, and then heat in a tube furnace under Ar atmosphere at 5℃·min. -1 The temperature was increased to 500℃ at a certain heating rate, and then calcined at a constant temperature for 3 hours. The resulting powder is the catalyst support NiAl2O4-rGO-M.

[0061] (2) Preparation of Ni / NiAl2O4-rGO-M catalyst: 1.4865g Ni(NO3)2·6H2O was placed in a beaker, 10ml of anhydrous ethanol was added, and the mixture was stirred until completely dissolved. 1.0g NiAl2O4-rGO-M support was impregnated in the above solution, stirred at room temperature for 24h, slowly evaporated to dryness in a water bath at 60℃, dried at 120℃ for 12h, then calcined in a tube furnace under argon protection at 450℃ for 1.5h, and reduced at 500℃ for 1.5h in a mixed gas atmosphere of H2 and N2 containing 50vol% H2 to obtain Ni / NiAl2O4-rGO-M catalyst, denoted as 30Ni / NiAl2O4-rGO-M, wherein the Ni loading is 30.0wt%.

[0062] The catalyst performance test results show (see) Figure 3a and 3b The catalyst prepared in this comparative example can reduce the CO concentration in the outlet gas to below 10 ppm in the temperature range of 240-260℃, while keeping the CH4 concentration below 2.0%, i.e., the selectivity is greater than 50%.

Claims

1. The application of a Ni / NiAl2O4-rGO catalyst in the low-temperature selective methanation of CO, characterized in that, The catalyst is used for the deep removal of CO from hydrogen-rich gas. The catalyst is a metal-supported catalyst with Ni as the active component and nickel-aluminum spinel-reduced graphene oxide composite material as the support. The method for preparing the catalyst includes the following steps: (1) Preparation of NiAl2O4-rGO composite support NiCl2·6H2O and AlCl3 were dissolved in water and denoted as solution A; NaOH and NaAlO2 were dissolved in water and denoted as solution B; NaAlO2 and GO were added to water to form a suspension solution and denoted as C; under an inert gas atmosphere and at a certain temperature, solutions A and B were simultaneously added dropwise to suspension solution C at the same rate to carry out a coprecipitation reaction. The pH value was adjusted by stirring, and the solution was aged, filtered, washed, dried, and calcined under an inert gas atmosphere to obtain the NiAl2O4-rGO composite support. (2) Preparation of Ni / NiAl2O4-rGO catalyst The NiAl2O4-rGO composite support was impregnated in anhydrous ethanol containing Ni(NO3)2·6H2O, and then dried, calcined and reduced under an inert gas atmosphere to obtain the Ni / NiAl2O4-rGO catalyst.

2. The application of the Ni / NiAl2O4-rGO catalyst according to claim 1 in the low-temperature selective methanation of CO, characterized in that, In step (1), the total nickel-aluminum molar ratio Ni:Al in solutions A, B, and C is 0.4 to 0.6:1; In step (1), the mass ratio of NiAl2O4 to GO in the support is 30 to 60:1; In step (1), the coprecipitation reaction temperature is controlled at 60–90 °C; In step (1), the pH is controlled between 9.0 and 11.

0.

3. The application of the Ni / NiAl2O4-rGO catalyst according to claim 1 in the low-temperature selective methanation of CO, characterized in that, In step (1), the calcination temperature is 400-600℃.

4. The application of the Ni / NiAl2O4-rGO catalyst according to claim 1 in the low-temperature selective methanation of CO, characterized in that, In step (2), the Ni loading of the catalyst is 10.0 to 40.0 wt%.

5. The application of the Ni / NiAl2O4-rGO catalyst according to claim 1 in the low-temperature selective methanation of CO, characterized in that, In step (2), the soaking time is 12 to 48 hours.

6. The application of the Ni / NiAl2O4-rGO catalyst according to claim 1 in the low-temperature selective methanation of CO, characterized in that, In step (2), the roasting temperature is 400-500℃.

7. The application of the Ni / NiAl2O4-rGO catalyst according to claim 1 in the low-temperature selective methanation of CO, characterized in that, In step (2), the reduction temperature is 450 to 600°C.

8. The application of the Ni / NiAl2O4-rGO catalyst according to claim 1 in the low-temperature selective methanation of CO, characterized in that, In steps (1) and (2), the inert gas is nitrogen or argon.

9. The application of the Ni / NiAl2O4-rGO catalyst according to any one of claims 1-8 in the low-temperature selective methanation of CO, characterized in that, The concentration of CO in the hydrogen-rich gas is 0.5–2.0 vol%, the CO low-temperature selective methanation reaction temperature is 185–240 °C, and the reaction space velocity is 4500–7500 ml·h. -1 ·g -1 .

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