Preparation method and application of nickel-magnesium bifunctional material modified by precious metal

Abstract

The invention discloses a preparation method and application of a noble metal-modified nickel-magnesium bifunctional material, and the modification method comprises the following steps: adding a noble metal precursor, namely ruthenium nitrosyl nitrate or palladium nitrate dihydrate, into deionized water, stirring until the mixture is completely dissolved to obtain a noble metal solution, adding a charcoal-based nickel-magnesium bifunctional material into the noble metal solution, stirring, filtering, washing, and drying to obtain the noble metal-modified nickel-magnesium bifunctional material. Transferring the mixed solution into an oil bath pan, and drying while stirring until the moisture is completely evaporated; and transferring the solid substance into a crucible, and roasting under the protection of nitrogen atmosphere to obtain the modified nickel-magnesium bifunctional material. On the basis of the biochar-based nickel-magnesium bifunctional material, precious metal is further introduced for modification to form Ru-Ni-MgO (at) NC with a special structure, so that the anti-poisoning ability of the biochar-based nickel-magnesium bifunctional material in a real smoke environment is greatly enhanced, and the biochar-based nickel-magnesium bifunctional material not only has excellent ICCM performance under an ideal condition, but also has excellent anti-poisoning ability in a real smoke environment. And excellent ICCM performance and long-term stability can be still maintained under the condition of water-containing and oxygen-containing simulated flue gas.

Description

Technical Field

[0001] This invention belongs to the field of integrated flue gas carbon capture and in-situ methanation technology, specifically relating to a method for preparing and applying a precious metal-modified nickel-magnesium bifunctional material. Background Technology

[0002] Against the backdrop of global efforts to address climate change and accelerate carbon emission reduction strategies, the development of efficient and low-energy carbon dioxide capture and utilization (CCU) technologies has become a crucial direction for technological innovation. Traditional carbon capture technologies are often independent of storage or utilization processes, resulting in low system integration and generally high energy consumption, complex processes, and insufficient economic viability. In recent years, integrated carbon capture and in-situ utilization (ICCU) technologies have emerged, providing a new pathway for low-cost, low-energy carbon dioxide resource utilization. This technology utilizes bifunctional materials (DFM) to couple the carbon dioxide capture and catalytic conversion processes in a single reactor, significantly simplifying the system structure and reducing operating energy consumption, thereby promoting closed-loop utilization of carbon dioxide. Among these, the Sabatier reaction pathway, which catalytically synthesizes methane through the hydrogenation of carbon dioxide, has promising industrial application prospects because its products can be easily integrated into existing natural gas infrastructure. Such bifunctional materials must possess both high carbon dioxide adsorption capacity and excellent catalytic hydrogenation activity, and are typically composed of alkaline metal oxides (such as MgO and CaO) and transition metals (such as Ni). Among numerous material systems, Ni / MgO-based bifunctional materials have become a research hotspot in this field due to the high catalytic activity of the Ni component, suitable cost, and the high degree of matching between the MgO adsorption temperature and the methanation reaction conditions, demonstrating significant application potential.

[0003] Currently, a large number of high-performance bifunctional materials have been developed for integrated carbon capture and in-situ methanation (ICCM) technology. However, most of the current research is conducted under ideal conditions. When applying ICCM technology to practical industrial applications, especially for treating industrial flue gas rich in water vapor and residual oxygen from coal-fired power plants and steel mills, DFM faces a severe poisoning challenge. Various complex reactions can occur between oxygen and the catalyst, especially at high temperatures, where oxygen can react with metal catalysts, leading to oxidation or sintering and thus reducing catalytic activity. Zouhair et al. found that after introducing O2, the methane yield of the best-performing material decreased from 210 μmol CH4 / g to 105 μmol CH4 / g, due to the oxidation of Ni active sites. Zhao et al. studied the effect of oxygen on Ni… 0.05 / CaO 0.95The effects of oxygen on the performance of bifunctional materials revealed that the presence of oxygen leads to the oxidation of Ni, reducing the catalytic performance of DFMs. Water vapor, another common component of flue gas, may compete with CO2 for adsorption, reducing CO2 adsorption capacity. It may also negatively impact the catalyst, causing water molecules to occupy the active sites, affecting carbon dioxide adsorption and conversion. Li et al. investigated the effect of H2O on the performance of DFMs, finding that they exhibited high CO2 adsorption and hydrogenation performance under dry conditions, while performance significantly decreased under humid conditions. More challenging is the potential synergistic effect between H2O and O2, which poses a significant challenge to the performance and stability of DFMs. However, the mechanisms by which H2O and O2 affect the performance and long-term stability of DFMs remain unclear, and effective anti-poisoning strategies are rarely reported. This has become a key bottleneck restricting the transition of ICCM technology from the laboratory to practical applications. Summary of the Invention

[0004] To address at least one of the aforementioned problems, this invention provides a method for preparing and applying a noble metal-modified nickel-magnesium bifunctional material.

[0005] To achieve the above objectives, the present invention employs the following technical means: The first aspect of this invention provides a method for preparing a noble metal-modified nickel-magnesium bifunctional material, comprising the following steps: The noble metal precursor, ruthenium nitrite nitrite or palladium nitrate dihydrate, is added to deionized water and stirred until completely dissolved to obtain a noble metal solution. Biochar-based nickel-magnesium bifunctional material is then added to the noble metal solution and stirred. The added noble metal accounts for 2%-4% of the mass of the biochar-based nickel-magnesium bifunctional material. The mixed solution is transferred to an oil bath and dried while stirring until the water is completely evaporated. The solid material is then transferred to a crucible and calcined under a nitrogen atmosphere to obtain the modified nickel-magnesium bifunctional material.

[0006] In some embodiments of the present invention, the preparation method of the biochar-based nickel-magnesium bifunctional material is as follows: calcining the carbon source at high temperature under a nitrogen atmosphere, cooling to room temperature, washing with deionized water, filtering, and drying to obtain biochar; adding Ni(NO3)2·6H2O and Mg(NO3)2·6H2O in a molar ratio of 1:1 to deionized water and stirring until homogeneous to obtain a solution; adding biochar to the solution and stirring; transferring the mixed solution to an oil bath and drying while stirring until the water is completely evaporated; transferring the solid material to a crucible and calcining under a nitrogen atmosphere to obtain the biochar-based nickel-magnesium bifunctional material.

[0007] In some embodiments of the present invention, the amount of biochar added is such that the mass ratio of the sum of the masses of nickel and magnesium metal to the mass of biochar is 1:(0.3-1.5); in a preferred embodiment, the amount of biochar added is such that the mass ratio of the sum of the masses of nickel and magnesium metal to the mass of biochar is 1:0.7.

[0008] In some embodiments of the present invention, the carbon source is guanine.

[0009] In some embodiments of the present invention, during the high-temperature carbonization process, the carbonization temperature is 1000-1200℃, the heating rate is 8-10℃ / min, and the temperature is maintained for 0.8-1.2h.

[0010] In some embodiments of the present invention, during the high-temperature carbonization process, the nitrogen atmosphere condition is 100 mL / min. In some embodiments of the present invention, the calcination conditions during the calcination of solid materials are: calcination temperature 550℃-650℃.

[0011] In some embodiments of the present invention, the heating rate is 4-5℃ / min and the calcination time is 1.5-2.5 h.

[0012] In some embodiments of the present invention, the nitrogen atmosphere condition during the calcination of the solid material is 100 mL / min.

[0013] A second aspect of the present invention provides a noble metal-modified nickel-magnesium bifunctional material prepared by the method described in the first aspect.

[0014] A third aspect of the invention provides the application of the precious metal-modified nickel-magnesium bifunctional material described in the second aspect in integrated flue gas carbon capture and in-situ methanation. In some embodiments of the invention, it can be applied to the carbon capture and in-situ methanation of integrated flue gas containing water and oxygen.

[0015] In some embodiments of the present invention, the application temperature is 250-300°C.

[0016] In some embodiments of the present invention, the noble metal-modified nickel-magnesium bifunctional material is pre-reduced in a 40% H2 atmosphere at 450-500°C before application.

[0017] Beneficial effects of the present invention Compared with existing technologies, this invention has the following advantages: This invention provides a novel bifunctional material based on nitrogen-doped biochar support with excellent low-temperature ICCM performance. By further introducing noble metals for modification, a Ru-Ni-MgO@NC material with a special structure is formed, which significantly enhances its resistance to poisoning in real flue gas environments.

[0018] The one-pot preparation process employed in this invention is simple, environmentally friendly, and produces low-cost biochar-based bifunctional materials that can achieve high-performance CO2 capture and in-situ methanation of flue gas. The results of the examples demonstrate that the ruthenium-modified biochar-based bifunctional materials prepared in this invention not only exhibit excellent ICCM performance under ideal conditions but also maintain excellent ICCM performance and long-term stability under simulated flue gas conditions containing water and oxygen. Attached Figure Description

[0019] Figure 1 SEM images of the bifunctional materials prepared in Examples 3 and 6 of the present invention are shown; wherein, (a) is Example 1 and (b) is Example 6; Figure 2 Low-magnification TEM images of the bifunctional materials prepared in Examples 3 and 6 of the present invention are shown; wherein, (a) is Example 1 and (b) is Example 6; Figure 3 High-magnification TEM images of the bifunctional materials prepared in Examples 3 and 6 of the present invention are shown; wherein, (a) is Example 1 and (b) is Example 6; Figure 4 The EDX mapping image of Ru-Ni-MgO@0.7NC prepared in Example 6 of the present invention is shown; Figure 5 The CO2 capture and methanation properties of the bifunctional materials prepared in Examples 1-5 of this invention are shown. Figure 6 The ICCM performance of the DFM prepared in Example 3 of this invention under different O2 concentrations is shown. Figure 7 The ICCM performance of the DFM prepared in Example 3 of the present invention under different humidity conditions is shown. Figure 8 The oxygen and water resistance properties of Ni-MgO@0.7NC prepared in Example 3 of this invention are shown. Figure 9 The oxygen and water resistance properties of Ru-Ni-MgO@0.7NC prepared in Example 6 of this invention are shown. Figure 10 The oxygen and water resistance properties of Pd-Ni-MgO@0.7NC prepared in Example 7 of this invention are shown. Figure 11 The cycling performance of Ru-Ni-MgO@0.7NC prepared in Example 6 of this invention is shown. Detailed Implementation

[0020] The following examples are used to illustrate preferred embodiments of the invention. Those skilled in the art will understand that the techniques disclosed in the examples represent techniques discovered by the inventors that can be used to implement the invention, and therefore can be considered preferred embodiments for implementing the invention. However, those skilled in the art should understand from this specification that many modifications can be made to the specific embodiments disclosed herein, still yielding the same or similar results, without departing from the spirit or scope of the invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and all materials disclosed herein and cited therein are incorporated herein by reference. Many equivalent techniques of specific embodiments of the invention described herein will be recognized or can be understood by ordinary experimentation by those skilled in the art. These equivalents will be included in the claims.

[0022] The technical solution of this application will be further described in detail below with reference to specific embodiments.

[0023] Example 1 First, 10g of guanine was weighed into a crucible. Then, the crucible was carbonized at 1000℃ in a muffle furnace under a nitrogen atmosphere (100mL / min) at a heating rate of 10℃ / min for 1 hour. After cooling to room temperature, the carbonized black material was removed and washed in deionized water with stirring for 12 hours. Subsequently, after washing with deionized water, filtration, and drying, nitrogen-doped carbon was obtained, named NC.

[0024] Then, 3.78 g of Ni(NO3)2·6H2O and 3.20 g of Mg(NO3)2·6H2O were added to 200 mL of deionized water and stirred for 20 min. Subsequently, 0.3 g of nitrogen-doped carbon was weighed and added to the above solution, and stirring continued for 30 min. The mixed solution was then transferred to an oil bath at 90 °C and dried while stirring until all moisture was evaporated. Finally, the resulting solid was transferred to a crucible and calcined at 600 °C for 2 h in a muffle furnace under a nitrogen atmosphere (nitrogen flow rate 100 mL / min, heating rate 5 °C / min). After the muffle furnace temperature cooled to room temperature, Ni-MgO@0.3NC was obtained.

[0025] Example 2 First, 10g of guanine was weighed into a crucible. Then, the crucible was carbonized at 1000℃ in a muffle furnace under a nitrogen atmosphere (100mL / min) at a heating rate of 10℃ / min for 1 hour. After cooling to room temperature, the carbonized black material was removed and washed in deionized water with stirring for 12 hours. Subsequently, after washing with deionized water, filtration, and drying, nitrogen-doped carbon was obtained, named NC.

[0026] Then, 3.78 g of Ni(NO3)2·6H2O and 3.20 g of Mg(NO3)2·6H2O were added to 200 mL of deionized water and stirred for 20 min. Next, 0.5 g of nitrogen-doped carbon was weighed and added to the solution, and stirring continued for 30 min. The mixture was then transferred to an oil bath at 90 °C and dried while stirring until all moisture was evaporated. Finally, the resulting solid was transferred to a crucible and calcined at 600 °C for 2 h in a muffle furnace under nitrogen atmosphere (nitrogen flow rate 100 mL / min, heating rate 5 °C / min). After the muffle furnace temperature cooled to room temperature, Ni-MgO@0.5NC was obtained.

[0027] Example 3 First, 10g of guanine was weighed into a crucible. Then, the crucible was carbonized at 1000℃ in a muffle furnace under a nitrogen atmosphere (100mL / min) at a heating rate of 10℃ / min for 1 hour. After cooling to room temperature, the carbonized black material was removed and washed in deionized water with stirring for 12 hours. Subsequently, after washing with deionized water, filtration, and drying, nitrogen-doped carbon was obtained, named NC.

[0028] Then, 3.78 g of Ni(NO3)2·6H2O and 3.20 g of Mg(NO3)2·6H2O were added to 200 mL of deionized water and stirred for 20 min. Subsequently, 0.7 g of nitrogen-doped carbon was weighed and added to the above solution, and stirring continued for 30 min. The mixed solution was then transferred to an oil bath at 90 °C and dried while stirring until all moisture was evaporated. Finally, the resulting solid was transferred to a crucible and calcined at 600 °C for 2 h in a muffle furnace under a nitrogen atmosphere (nitrogen flow rate 100 mL / min, heating rate 5 °C / min). After the muffle furnace temperature cooled to room temperature, Ni-MgO@0.7NC was obtained.

[0029] Example 4 First, 10g of guanine was weighed into a crucible. Then, the crucible was carbonized at 1000℃ in a muffle furnace under a nitrogen atmosphere (100mL / min) at a heating rate of 10℃ / min for 1 hour. After cooling to room temperature, the carbonized black material was removed and washed in deionized water with stirring for 12 hours. Subsequently, after washing with deionized water, filtration, and drying, nitrogen-doped carbon was obtained, named NC.

[0030] Then, 3.78 g of Ni(NO3)2·6H2O and 3.20 g of Mg(NO3)2·6H2O were added to 200 mL of deionized water and stirred for 20 min. Next, 1 g of nitrogen-doped carbon was weighed and added to the solution, and stirring continued for 30 min. The mixture was then transferred to an oil bath at 90 °C and dried while stirring until all moisture was evaporated. Finally, the resulting solid was transferred to a crucible and calcined at 600 °C for 2 h in a muffle furnace under nitrogen atmosphere (nitrogen flow rate 100 mL / min, heating rate 5 °C / min). After the muffle furnace temperature cooled to room temperature, Ni-MgO@1NC was obtained.

[0031] Example 5 First, 10g of guanine was weighed into a crucible. Then, the crucible was carbonized at 1000℃ in a muffle furnace under a nitrogen atmosphere (100mL / min) at a heating rate of 10℃ / min for 1 hour. After cooling to room temperature, the carbonized black material was removed and washed in deionized water with stirring for 12 hours. Subsequently, after washing with deionized water, filtration, and drying, nitrogen-doped carbon was obtained, named NC.

[0032] Then, 3.78 g of Ni(NO3)2·6H2O and 3.20 g of Mg(NO3)2·6H2O were added to 200 mL of deionized water and stirred for 20 min. Subsequently, 1.5 g of nitrogen-doped carbon was weighed and added to the above solution, and stirring continued for 30 min. The mixed solution was then transferred to an oil bath at 90 °C and dried while stirring until all moisture was evaporated. Finally, the resulting solid was transferred to a crucible and calcined at 600 °C for 2 h in a muffle furnace under a nitrogen atmosphere (nitrogen flow rate 100 mL / min, heating rate 5 °C / min). After the muffle furnace temperature cooled to room temperature, Ni-MgO@1.5NC was obtained.

[0033] Example 6 First, 0.33 g of ruthenium(III) nitrosyl nitrate was added to 200 mL of deionized water and stirred for 20 min until completely dissolved. Then, 9.9 g of Ni-MgO@0.7NC prepared in Example 3 was added to the solution and stirring continued for 30 min. The mixture was then transferred to an oil bath at 90 °C and dried while stirring until all moisture was evaporated. Finally, the resulting solid was transferred to a crucible and calcined at 600 °C for 2 h in a muffle furnace under nitrogen atmosphere (nitrogen flow rate 100 mL / min, heating rate 5 °C / min). After the muffle furnace temperature cooled to room temperature, ruthenium-modified biochar-based nickel-magnesium DFM was obtained, named Ru-Ni-MgO@0.7NC.

[0034] Example 7 First, 0.26 g of palladium(II) nitrate dihydrate was added to 200 mL of deionized water and stirred for 20 min until completely dissolved. Then, 9.9 g of Ni-MgO@0.7NC prepared in Example 3 was added to the solution and stirring continued for 30 min. The mixture was then transferred to an oil bath at 90 °C and dried while stirring until all moisture was evaporated. Finally, the resulting solid was transferred to a crucible and calcined at 600 °C for 2 h in a muffle furnace under nitrogen atmosphere (nitrogen flow rate 100 mL / min, heating rate 5 °C / min). After the muffle furnace temperature cooled to room temperature, palladium-modified biochar-based nickel-magnesium DFM was obtained, named Pd-Ni-MgO@0.7NC.

[0035] Performance testing and characterization (1) The bifunctional material prepared in Example 6 was subjected to SEM testing, and the results are as follows: Figure 1 As shown.

[0036] Scanning electron microscopy revealed that Ru-Ni-MgO@0.7NC exhibits micron-sized irregular particles and a rough surface, which differs significantly from the morphology of unmodified Ni-MgO@0.7NC. This difference likely indicates that secondary calcination caused a substantial change in its morphology. Furthermore, Ru-Ni-MgO@0.7NC displays a distinct porous structure, which contributes to improving its specific surface area and the dispersion of active sites.

[0037] (2) TEM testing and analysis were performed on the bifunctional materials prepared in Examples 3 and 6. Figures 2 to 4 .

[0038] Figure 2 Image a shows a low-magnification TEM image of Ni-MgO@0.7NC prepared in Example 3. As can be seen from the image, the sample mainly consists of well-dispersed spherical nanoparticles dispersed on carbon nanosheets, and the size distribution of the nanoparticles is relatively uniform. Figure 2 b shows a low-magnification TEM image of Ru-Ni-MgO@0.7NC prepared in Example 6. The image shows that the sample exhibits a morphology characterized by well-dispersed spherical nanoparticles uniformly distributed on a carbon nanosheet support, with a concentrated particle size distribution, demonstrating high size uniformity. The nanoparticles loaded on the carbon nanosheets represent the two types of active sites in the material, further confirming the excellent dispersibility of the active components on the support surface.

[0039] Figure 3 Image a presents a high-resolution TEM image of Ni-MgO@0.7NC. The clear lattice fringes indicate excellent crystallinity of the material. The measured interplanar spacings in the image are 0.21 and 0.35 nm, corresponding to Mg... 0.4 Ni 0.6The O (200) crystal plane and the (002) crystal plane of nitrogen-doped carbon. From Figure 3 As can be seen from b, Ru-Ni-MgO@0.7NC exhibits a morphology basically consistent with Ni-MgO@0.7NC, and the clear lattice fringes indicate that the material has excellent crystallinity. Different lattice fringes can be observed in the high-magnification TEM image of Ru-Ni-MgO@0.7NC. The measured interplanar spacings in the image are 0.214 and 0.235 nm, respectively, corresponding to Mg... 0.4 Ni 0.6 The O (200) crystal plane and the Ru (100) crystal plane indicate that ruthenium was successfully introduced.

[0040] Figure 4 The EDX mapping shows that the signals of C and N are consistently distributed throughout the material, while the distributions of O, Mg, and Ni largely overlap. This further indicates that the two active sites form a solid solution of Mg. 0.4 Ni 0.6 O, and the distribution of the newly introduced precious metal element Ru is also relatively uniform.

[0041] (3) The CO2 adsorption and methanation performance of the bifunctional materials prepared in Examples 1-6 and Comparative Examples 1-2 under different working conditions were tested by fixed-bed adsorption breakthrough experiments.

[0042] All materials must undergo pre-reduction treatment at 500℃ in a 40% H2 atmosphere before ICCM performance testing. The specific test procedure is as follows: First, approximately 200 mg of DFM is weighed and loaded into a fixed-bed reactor. The temperature is raised to 500℃ at a rate of 10℃ / min using pure N2 (space velocity 30000 mL / h / g). Then, the gas is replaced with an equal flow rate of 40% H2 mixture for DFM reduction. After reduction, the reactor is purged with pure N2 for 20 minutes until the outlet hydrogen concentration drops to zero. Next, the reactor temperature is adjusted to the target test temperature (250℃ or 300℃) to begin ICCM testing. ICCM testing begins with a 20-minute CO2 capture using a 100 mL / min 10% CO2 mixture. Then, the gas is switched to an equal flow rate of 10% H2 mixture for a 20-minute in-situ CO2 methanation reaction. After the reaction, the reactor is purged with pure N2 for 20 minutes. By varying the reaction temperature, tests can be conducted at different temperatures. Repeating the trap-methanation-purging process at the same temperature allows for the evaluation of the material's cyclic stability. Modifying the inlet gas composition during the trapping stage allows for the investigation of the effects of O2 and H2O on ICCM performance. This study tested the synergistic effect of a two-component O2 and H2O (30% H2O + 5% O2) combination on ICCM performance. The above experiments yielded curves showing the changes in CO2, CO, H2, and CH4 concentrations over time. The following formulas can be used to calculate CO2 adsorption / desorption capacity and conversion, CO formation, CH4 formation, and selectivity.

[0043]

[0044]

[0045]

[0046]

[0047] Here q adCO2 (mmol / g) represents the adsorption capacity, Q represents the total gas flow rate (mL / min), and C represents the total gas flow rate. in (mg / m 3 ) and C out q represents the CO2 inlet and outlet mass concentrations, respectively, and m represents the DFM mass. X (mmol / g) represents the amount produced, C X (mg / m 3 ) represents the mass concentration, where X is one of CO, CH4, and desorbed CO2. Mr is the relative molecular mass of the corresponding molecule. η is the CO2 conversion rate, X CH4 CH4 selectivity.

[0048] Figure 5 The CO2 capture and methanation performance of the bifunctional materials prepared in Examples 1-5 at 300℃ is shown. It is evident that the DFM with an NC addition of 0.7 exhibits the best performance, indicating that this ratio achieves the optimal structure-property relationship of the material structure, providing sufficient basic sites for CO2 adsorption while ensuring full exposure of Ni active sites, thus realizing an ideal integration of adsorption and catalytic functions. Too low a support ratio (0.3NC, 0.5NC) leads to poor dispersion of adsorption-catalytic active sites, preventing them from fully functioning. Conversely, too high a support ratio (1.0NC, 1.5NC) results in excessive separation of adsorption-catalytic active sites, increasing mass transfer resistance and hindering subsequent hydrogenation conversion of captured CO2. Overall, all five bifunctional materials exhibit excellent low-temperature ICCM performance, with the material with an NC addition of 0.7 showing the best performance.

[0049] Figure 6 The CO2 capture and methanation performance of Ni-MgO@0.7NC prepared in Example 3 under different oxygen concentrations is shown.

[0050] The results show that the introduction of even a trace amount of oxygen (3%) leads to a sharp decline in material performance: CO2 adsorption capacity decreased from 1.46 mmol / g to 1.15 mmol / g, CO2 conversion rate plummeted from 81.62% to 44.63%, CH4 yield halved from 1.18 mmol / g to 0.49 mmol / g, while CO selectivity increased and CH4 selectivity decreased to 96.38%. As the oxygen concentration increased to 10%, all performance parameters deteriorated further, indicating that oxygen and CO2 / H2 competed more fiercely for catalytic sites and may have directly oxidized the key active components.

[0051] Figure 7 The CO2 capture and methanation performance of Ni-MgO@0.7NC prepared in Example 3 under different humidity conditions is shown.

[0052] The results show that the introduction of water vapor significantly inhibited the ICCM process, and this effect intensified with increasing humidity. Under humidity conditions of 10%, 30%, and 50%, the CO2 adsorption capacity of the material decreased from 1.46 mmol / g under dry conditions to 1.23, 1.20, and 1.13 mmol / g, respectively. This indicates that water molecules competed with CO2 for adsorption sites, occupying some active sites and directly reducing the CO2 capture capacity. More importantly, this competitive adsorption further affected the subsequent hydrogenation process, causing the CO2 conversion rate to decrease from 81.62% to 75.80%, 73.54%, and 61.18%, respectively, and the CH4 yield to decrease from 1.18 mmol / g to 0.92, 0.91, and 0.67 mmol / g, respectively. Of particular note is the significant increase in CO yield (0.02 mmol / g) under 50% high humidity, coupled with a decrease in CH4 selectivity to 97.15%. This strongly suggests that the presence of water vapor may have promoted the water-gas shift reaction or other side reaction pathways, altering the reaction selectivity. Although Ni-MgO@0.7NC exhibits excellent ICCM performance in an inert atmosphere, it is extremely sensitive to oxygen and water and exhibits poor resistance to oxygen and water poisoning. This finding indicates that a new generation of bifunctional material systems with high resistance to poisoning must be developed for practical applications; otherwise, the material will face the risk of rapid deactivation.

[0053] Figure 8-10 The CO2 capture and methanation performance of the DFM prepared in Examples 3, 6 and 7 under the synergistic influence of water and oxygen.

[0054] The results show that the coexistence of H2O and O2 has a severe synergistic poisoning effect on the ICCM process, but the degree of damage is highly dependent on the composition of DFMs. For unmodified Ni-MgO@0.7NC ( Figure 8 Under the synergistic influence of 30% H2O and 5% O2, its performance underwent a catastrophic decline: CO2 conversion plummeted from 81.62% to 22.73%, CH4 yield dropped from 1.18 mmol / g to 0.28 mmol / g, and CH4 selectivity decreased significantly. More seriously, after the influencing atmosphere was removed, its performance recovery was very limited (CO2 conversion only recovered to 55.49%), confirming our conclusion above: O2 leads to irreversible oxidation of Ni active sites, and the coexistence of H2O may further exacerbate this oxidation or form more stable hydroxyl oxide species, resulting in permanent deactivation.

[0055] The introduction of Pd has shown a certain protective effect. Figure 9Under the same influence, its CO2 conversion remained at 54.86%, but the CH4 selectivity dropped sharply to 90.75%, while the CO yield increased. This suggests that Pd may have preferentially catalyzed the reverse water-gas shift reaction (RWGS) or the CO pathway, sacrificing CH4 selectivity while maintaining overall activity. After the influence was removed, its performance showed partial reversibility (conversion recovered to 66.04%, selectivity recovered to 99.60%), proving that Pd protected Ni active sites from deep oxidation to some extent, but it may have altered the reaction pathway itself. The Ru-modified catalyst performed the best. Figure 10 It almost completely reversed the negative effects of synergistic poisoning. Under harsh conditions of 30% H2O + 5% O2, its performance not only did not decline, but the CO2 conversion rate actually increased from 68.51% to 73.57%, achieving 100% CH4 selectivity (CO yield of 0). This remarkable performance suggests that Ru likely acts as a highly efficient oxygen scavenger, preferentially activating and dissociating O2 and H2O molecules, thereby protecting Ni and MgO sites from oxidation and hydroxylation poisoning, and may even utilize the active H* species generated by water dissociation to promote the hydrogenation process. Subsequent testing under a pure atmosphere completely restored its high performance (conversion rate of 75.24%), demonstrating its excellent anti-poisoning ability and complete reversibility.

[0056] Figure 11 This is a test of the stability of Ru-Ni-MgO@0.7NC prepared in Example 6 under the synergistic effects of water and oxygen in multiple cycles.

[0057] The results showed that the material exhibited exceptional stability and continuously optimized performance throughout the cycling tests. Its CO2 conversion steadily increased from 70.65% in the first cycle to 84.56% in the seventh cycle, with a simultaneous increase in CH4 yield (from 0.77 to 0.86 mmol / g), while maintaining 100% CH4 selectivity (CO yield was 0). More importantly, its CO2 adsorption capacity remained stable at around 1.05 mmol / g, indicating perfect protection of its adsorption sites. This superior performance is attributed to the dual function of Ru: firstly, as a highly efficient oxygen scavenger, Ru preferentially activates and dissociates O2 and H2O molecules, protecting Ni and MgO sites from irreversible oxidation; secondly, Ru may promote H2 dissociation, providing a richer variety of active hydrogen species for the hydrogenation process, thus continuously optimizing reaction kinetics in harsh environments and exhibiting a positive self-regulating process.

[0058] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by this application.

Claims

1. A method for preparing a noble metal-modified nickel-magnesium bifunctional material, characterized in that, Includes the following steps: The noble metal precursor, ruthenium nitrite nitrite or palladium nitrate dihydrate, is added to deionized water and stirred until completely dissolved to obtain a noble metal solution. Biochar-based nickel-magnesium bifunctional material is then added to the noble metal solution and stirred. The added noble metal accounts for 2%-4% of the mass of the biochar-based nickel-magnesium bifunctional material. The mixed solution is transferred to an oil bath and dried while stirring until the water is completely evaporated. The solid material is then transferred to a crucible and calcined under a nitrogen atmosphere to obtain the noble metal-modified nickel-magnesium bifunctional material.

2. The method for preparing a noble metal-modified nickel-magnesium bifunctional material according to claim 1, characterized in that, The preparation method of the biochar-based nickel-magnesium bifunctional material is as follows: guanine, the carbon source, is carbonized at high temperature under a nitrogen atmosphere. After cooling to room temperature, it is washed with deionized water, filtered, and dried to obtain biochar. Ni(NO3)2·6H2O and Mg(NO3)2·6H2O in a molar ratio of 1:1 are added to deionized water and stirred until a solution is obtained. Biochar is added to the solution and stirred, with the mass ratio of nickel-magnesium metal to biochar being 1:(0.3-1.5). The mixed solution is transferred to an oil bath and dried while stirring until the water is completely evaporated. The solid material is transferred to a crucible and calcined under a nitrogen atmosphere to obtain the biochar-based nickel-magnesium bifunctional material.

3. The method for preparing a noble metal-modified nickel-magnesium bifunctional material according to claim 2, characterized in that, The mass ratio of nickel and magnesium metal to biochar was 1:0.

7.

4. The method for preparing a noble metal-modified nickel-magnesium bifunctional material according to claim 2, characterized in that, During the high-temperature carbonization process, the carbonization temperature is 1000-1200℃, the heating rate is 8-10℃ / min, and the holding time is 0.8-1.2h.

5. The method for preparing a noble metal-modified nickel-magnesium bifunctional material according to claim 2, characterized in that, During the calcination of solid materials, the calcination conditions are: calcination temperature 550℃-650℃.

6. The method for preparing a noble metal-modified nickel-magnesium bifunctional material according to claim 5, characterized in that, The heating rate is 4-5℃ / min, and the calcination time is 1.5-2.5 h.

7. The noble metal-modified nickel-magnesium bifunctional material prepared by the method according to any one of claims 1-6.

8. The application of the precious metal-modified nickel-magnesium bifunctional material as described in claim 7 in integrated flue gas carbon capture and in-situ methanation.

9. The application according to claim 8, characterized in that: The application temperature is 200-400℃.

10. The application according to claim 8, characterized in that: The precious metal-modified nickel-magnesium bifunctional material is pre-reduced in a 40% H2 atmosphere at 450-500℃ before application.

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