CeCuMnK / CeNiCa bifunctional material and preparation method and application thereof

Abstract

The application belongs to the technical field of gas adsorption and conversion, and provides a CeCuMnK / CeNiCa bifunctional material, a preparation method and application thereof. The CeCuMnK / CeNiCa bifunctional material provided by the application comprises a CeNiCa core and a CeCuMnK composite material loaded on the CeNiCa core; the CeNiCa core comprises calcium oxide, cerium oxide and nickel oxide; and the CeCuMnK composite material comprises cerium oxide, copper oxide, manganese oxide and potassium oxide. The CeCuMnK / CeNiCa bifunctional material of the application can achieve a NOx capture efficiency of >90% after reduction, and in a subsequent hydrogenation conversion stage, the adsorbed NOx is converted into harmless N2 (N2 selectivity >90%) with high selectivity, the generation of harmful by-product NH3 is effectively inhibited, and secondary pollution is avoided.

Description

Technical Field

[0001] This invention relates to the field of gas adsorption and conversion technology, and in particular to a CeCuMnK / CeNiCa bifunctional material, its preparation method, and its application. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) are key technologies for addressing global climate change and achieving carbon neutrality. Integrated carbon capture and utilization (ICCUS) technology, as a transformative technology, converts captured CO2 in situ into high-value chemicals (such as CH4), eliminating the energy-intensive CO2 desorption, purification, and compression steps required in traditional CCUS technologies, thus offering significant energy efficiency advantages.

[0003] Most existing research on integrated carbon capture and in-situ conversion (ICCU) technology is conducted under ideal atmospheres. However, actual industrial flue gas (such as flue gas emitted from the steel, cement, and power generation industries) contains impurity gases in addition to CO2, including O2, H2O, SOx, and NOx. Among these, NOx, as an acidic impurity gas, poses a serious challenge to the ICCU process.

[0004] The applicant's previously developed patented technology (CN118454684A) proposed a CeNiCa-based composite material that can capture CO2 and catalytically oxidize pollutants such as CO and HC. However, this technology has limitations in treating NOx: the substances generated from NOx conversion contain a large amount of NH3, resulting in incomplete purification; that is, the nitrogen selectivity is not high. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a CeCuMnK / CeNiCa bifunctional material, its preparation method, and its applications. The CeCuMnK / CeNiCa bifunctional material provided by this invention can selectively convert NOx into N2, achieving deep purification of NOx.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a CeCuMnK / CeNiCa bifunctional material, comprising a CeNiCa core and a CeCuMnK composite material supported on the CeNiCa core; The CeNiCa core comprises calcium oxide, cerium oxide, and nickel oxide; The CeCuMnK composite material includes cerium oxide, copper oxide, manganese oxide, and potassium oxide.

[0007] Preferably, in the CeNiCa core, the molar ratio of cerium, nickel and calcium is 0.08~0.12:0.18~0.22:1.

[0008] Preferably, the molar ratio of cerium in the CeCuMnK composite material to calcium in the CeNiCa core is 0.018~0.022:1; The molar ratio of copper in the CeCuMnK composite material to calcium in the CeNiCa core is 0.018~0.022:1; The molar ratio of manganese in the CeCuMnK composite material to calcium in the CeNiCa core is 0.018~0.022:1; The molar ratio of potassium in the CeCuMnK composite material to calcium in the CeNiCa core is 0.18~0.22:1.

[0009] This invention also provides a method for preparing the CeCuMnK / CeNiCa bifunctional material described in the above technical solution, comprising the following steps: Provide CeNiCa composite powder; A soluble cerium salt, soluble copper salt, soluble manganese salt, soluble potassium salt, and water are mixed to form an impregnation solution; The CeNiCa composite material powder was added to the impregnation solution, and impregnation and evaporation were performed sequentially to obtain the precursor; The precursor is subjected to a first calcination to obtain the CeCuMnK / CeNiCa bifunctional material.

[0010] Preferably, the method for preparing the CeNiCa composite powder includes the following steps: Soluble calcium salt, soluble nickel salt, soluble cerium salt, citric acid and water are mixed and subjected to complexation reaction and evaporation in sequence to obtain a gel-like substance; The gelatinous substance was dried to obtain an intermediate product; The intermediate product is subjected to a second calcination to obtain the CeNiCa composite material powder.

[0011] Preferably, in the process of preparing the gel-like substance, the molar ratio of the citric acid to the total molar ratio of the soluble modified, soluble nickel salt and soluble cerium salt is 0.8~1.2:1.

[0012] Preferably, the complexation reaction is carried out at a temperature of 20-30°C for 3-5 hours. The evaporation temperature is 70~90℃; The drying temperature is 100~150℃, and the time is 10~15h; The second calcination temperature is 500~600℃, the heating rate to the second calcination temperature is 4~6℃ / min, and the time is 3~5h.

[0013] Preferably, the temperature of the first calcination is 500~600℃, the heating rate to the first calcination temperature is 4~6℃ / min, and the time is 3~5h.

[0014] The present invention also provides a method for purifying NOx in flue gas, comprising the following steps: The active material is reduced to obtain a reduced active material; The flue gas to be treated is captured by the reducing active material to obtain the active material for capturing the gas; Hydrogen gas is passed through the active material used to capture the gas for in-situ conversion to obtain purified gas. The active material is the CeCuMnK / CeNiCa bifunctional material described in the above technical solution or the CeCuMnK / CeNiCa bifunctional material prepared by the preparation method described in the above technical solution.

[0015] Preferably, the atmosphere for the reduction treatment includes nitrogen and hydrogen, with a pressure of 0.8~1.2 atm, a temperature of 350~650℃, and a time of 0.5~1.5h; The trapping pressure is 0.8~1.2 atm, the temperature is 200~400℃, and the time is 1~10 min; The in-situ transformation is carried out at a pressure of 0.8~1.2 atm, a temperature of 350~650℃, and a time of 0.5~1.5h.

[0016] This invention provides a CeCuMnK / CeNiCa bifunctional material.

[0017] This invention has the following advantages: (1) Achieved deep NOx purification: The CeCuMnK / CeNiCa bifunctional material (DFM) proposed in this invention can achieve deep NOx purification, solving the problems of nitrate poisoning of DFM during the NOx capture stage and secondary pollution caused by hydrogenation reduction to NH3 during the conversion stage in the existing ICCU (Integrated Carbon Capture and Utilization) technology.

[0018] (2) NOx is selectively stored in the CeCuMnK component, which significantly improves the NOx capture efficiency under complex flue gas atmosphere; it also achieves CO2 capture and methanation to a certain extent.

[0019] (3) High efficiency of NOx capture and high selectivity of conversion: The CeCuMnK / CeNiCa bifunctional material of the present invention can achieve a NOx capture efficiency of >90% after reduction, and in the subsequent hydrogenation conversion stage, the adsorbed NOx is highly selectively converted into harmless N2 (N2 selectivity >90%), effectively inhibiting the generation of harmful byproduct NH3 and avoiding secondary pollution.

[0020] Source of technical benefits: This advantage stems from the synergistic catalytic effect of Cu, Mn, Ce, and K in the “CeCuMnK” component, as well as the optimized low-temperature adsorption (250℃) and medium-to-high-temperature conversion (500℃) process conditions.

[0021] (4) Excellent cycle stability: After 10 “capture-conversion” cycles, the NOx purification performance of the material remains stable, showing excellent durability and practical application potential. Thanks to the stability of the material structure, the accumulation and poisoning of NOx species are avoided. Attached Figure Description

[0022] Figure 1 A comparison chart of NOx adsorption and conversion performance of different materials; Figure 2 This graph shows the concentration changes of the main components in different materials during performance testing. Figures 3-5 XPS analysis of CeCuMnK / CeNiCa bifunctional materials before and after reduction; Figure 6 The results of the cycle performance test of CeCuMnK / CeNiCa obtained in Example 1 are shown, where (a) is the CO2 capture and conversion performance, and (b) is the NOx adsorption and catalytic reduction performance. Figure 7 The cycling performance test results of CeCuMnK / CeNiCa obtained in Comparative Example 1 are shown, where (a) represents CO2 capture and conversion performance, and (b) represents NOx adsorption and catalytic reduction performance. Figure 8 The cycling performance test results of CeCuMnK / CeNiCa obtained in Comparative Example 2 are shown, where (a) represents CO2 capture and conversion performance, and (b) represents NOx adsorption and catalytic reduction performance. Figure 9 The cycling performance test results of CeCuMnK / CeNiCa obtained in Comparative Example 3 are shown, where (a) represents CO2 capture and conversion performance, and (b) represents NOx adsorption and catalytic reduction performance. Figure 10The cycling performance test results of CeCuMnK / CeNiCa obtained in Comparative Example 4 are shown, where (a) represents CO2 capture and conversion performance, and (b) represents NOx adsorption and catalytic reduction performance. Figure 11 The results of the cycle performance test of CeCuMnK / CeNiCa obtained in Comparative Example 5 are shown. (a) shows the CO2 capture and conversion performance, and (b) shows the NOx adsorption and catalytic reduction performance. Detailed Implementation

[0023] This invention provides a CeCuMnK / CeNiCa bifunctional material, comprising a CeNiCa core and a CeCuMnK composite material supported on the CeNiCa core; The CeNiCa core comprises calcium oxide, cerium oxide, and nickel oxide; The CeCuMnK composite material includes cerium oxide, copper oxide, manganese oxide, and potassium oxide.

[0024] The CeCuMnK / CeNiCa bifunctional material provided by this invention includes a CeNiCa core, which comprises calcium oxide, cerium oxide, and nickel oxide. In this invention, the molar ratio of cerium, nickel, and calcium in the CeNiCa core is preferably 0.08~0.12:0.18~0.22:1, more preferably 0.1:0.2:1. In this invention, the CeNiCa core uses CaO as the main CO2 adsorbent, Ni as the main catalytic active center, and CeO2 as a promoter; the CeNiCa core serves as a component for CO2 capture and in-situ methanation.

[0025] The CeCuMnK / CeNiCa bifunctional material provided by the present invention includes a CeCuMnK composite material supported on the CeNiCa core; the CeCuMnK composite material includes cerium oxide, copper oxide, manganese oxide and potassium oxide. In this invention, the molar ratio of cerium in the CeCuMnK composite material to calcium in the CeNiCa core is preferably 0.018~0.022:1, more preferably 0.02:1; the molar ratio of copper in the CeCuMnK composite material to calcium in the CeNiCa core is preferably 0.018~0.022:1, more preferably 0.02:1; the molar ratio of manganese in the CeCuMnK composite material to calcium in the CeNiCa core is preferably 0.018~0.022:1, more preferably 0.02:1; the molar ratio of potassium in the CeCuMnK composite material to calcium in the CeNiCa core is preferably 0.18~0.22:1, more preferably 0.2:1. In this invention, the CeCuMnK composite material uses K species as the main NOx adsorption site and Cu, Mn and Ce oxides as the main catalytic active centers for NO oxidation, NO2 storage and selective catalytic reduction of nitrate / nitrite; the CeCuMnK composite material serves as the NOx capture and selective catalytic reduction component.

[0026] In this invention, the CeCuMnK composite material is uniformly loaded onto the surface of the CeNiCa core in the form of nanoparticles, forming a rich interface.

[0027] This invention also provides a method for preparing the CeCuMnK / CeNiCa bifunctional material described in the above technical solution, comprising the following steps: Provide CeNiCa composite powder; A soluble cerium salt, soluble copper salt, soluble manganese salt, soluble potassium salt, and water are mixed to form an impregnation solution; The CeNiCa composite material powder was added to the impregnation solution, and impregnation and evaporation were performed sequentially to obtain the precursor; The precursor is subjected to a first calcination to obtain the CeCuMnK / CeNiCa bifunctional material.

[0028] Unless otherwise specified, the raw materials used in this invention are preferably commercially available products.

[0029] This invention provides CeNiCa composite powder. In this invention, the preparation method of the CeNiCa composite powder preferably includes the following steps: Soluble calcium salt, soluble nickel salt, soluble cerium salt, citric acid and water are mixed and subjected to complexation reaction and evaporation in sequence to obtain a gel-like substance; The gelatinous substance was dried to obtain an intermediate product; The intermediate product is subjected to a second calcination to obtain the CeNiCa composite material powder.

[0030] This invention involves mixing soluble calcium salt, soluble nickel salt, soluble cerium salt, citric acid, and water, and sequentially performing a complexation reaction and evaporation to obtain a gel-like substance. In this invention, the soluble calcium salt preferably includes calcium nitrate, the soluble nickel salt preferably includes nickel nitrate, and the soluble cerium salt preferably includes cerium nitrate. In the preparation of the gel-like substance, the molar ratio of citric acid to the total molar ratio of the soluble modified calcium salt, soluble nickel salt, and soluble cerium salt is preferably 0.8~1.2:1, more preferably 1:1. In this invention, the temperature of the complexation reaction is preferably 20~30℃, more preferably 25℃; the time is preferably 3~5h, more preferably 4h; the complexation reaction is preferably carried out under stirring. In this invention, the evaporation temperature is preferably 70~90℃, more preferably 80℃; this invention does not specifically limit the evaporation time, as long as the water is evaporated to a viscous consistency. In this invention, the gel-like substance is preferably a viscous gel-like substance.

[0031] After obtaining the gelatinous substance, the present invention dries the gelatinous substance to obtain an intermediate product. In the present invention, the drying temperature is preferably 100~150℃, specifically 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃; the drying time is preferably 10~15h, specifically 10h, 11h, 12h, 13h, 14h, or 15h; the drying is preferably carried out in an oven, and the drying process allows the gelatinous substance to expand. In the present invention, the intermediate product is preferably a fluffy foam.

[0032] After obtaining the intermediate product, the present invention subjectes the intermediate product to a second calcination to obtain the CeNiCa composite material powder. In the present invention, the intermediate product is preferably ground before the second calcination, and the grinding operation is not specifically limited. In the present invention, the temperature of the second calcination is preferably 500-600℃, more preferably 550℃; the heating rate to the second calcination temperature is preferably 4-6℃ / min, more preferably 5℃ / min; the time is preferably 3-5h, more preferably 4h; the second calcination is preferably carried out in a muffle furnace.

[0033] This invention involves mixing a soluble cerium salt, a soluble copper salt, a soluble manganese salt, a soluble potassium salt, and water to form an impregnation solution. In this invention, the soluble cerium salt is preferably cerium nitrate, the soluble copper salt is preferably copper nitrate, the soluble manganese salt is preferably manganese nitrate, and the soluble potassium salt is preferably potassium nitrate.

[0034] After obtaining the impregnation solution and CeNiCa composite material powder, the present invention adds the CeNiCa composite material powder to the impregnation solution, and performs impregnation and evaporation sequentially to obtain the precursor.

[0035] In this invention, the impregnation temperature is preferably room temperature, and the time is preferably 8-24 hours, more preferably 12 hours; the impregnation is preferably carried out under stirring conditions. In this invention, the evaporation temperature is preferably 70-90°C, more preferably 80°C; this invention does not specifically limit the evaporation time, as long as the moisture is completely removed.

[0036] After obtaining the precursor, the present invention subjectes the precursor to a first calcination to obtain the CeCuMnK / CeNiCa bifunctional material. In the present invention, the precursor is preferably dried before the first calcination, with the drying temperature preferably being 100-140°C, more preferably 120°C; the drying time is preferably 10-14 hours, more preferably 12 hours; the drying is preferably carried out in an oven. In the present invention, the first calcination temperature is preferably 500-600°C, more preferably 550°C; the heating rate to the first calcination temperature is preferably 4-6°C / min, more preferably 5°C / min; the time is preferably 3-5 hours, more preferably 4 hours; the first calcination is preferably carried out in a muffle furnace.

[0037] The present invention also provides a method for purifying NOx in flue gas, comprising the following steps: The active material is reduced to obtain a reduced active material; The flue gas to be treated is captured by the reducing active material to obtain the active material for capturing the gas; Hydrogen gas is passed through the active material used to capture the gas for in-situ conversion to obtain purified gas. The active material is the CeCuMnK / CeNiCa bifunctional material described in the above technical solution or the CeCuMnK / CeNiCa bifunctional material prepared by the preparation method described in the above technical solution.

[0038] This invention involves reducing an active material to obtain a reduced active material. In this invention, the atmosphere for the reduction treatment preferably includes nitrogen and hydrogen, with the hydrogen volume content preferably being 40-60%, more preferably 50%; the pressure is preferably 0.8-1.2 atm, specifically 1 atm; the temperature is preferably 350-650℃, more preferably 450-550℃, specifically 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, or 650℃; and the time is preferably 0.5-1.5 h, more preferably 1 h. In this invention, the reduction treatment is preferably carried out in a fixed-bed reactor.

[0039] In this invention, the reduction process can reduce metal oxides, such as reducing NiO to metallic Ni, and partially reducing Cu and Mn oxides.

[0040] After obtaining the reducing active material, the present invention uses the reducing active material to capture the flue gas to be treated, thereby obtaining the active material for capturing the gas. In the present invention, the flue gas to be treated preferably includes carbon dioxide, NO, oxygen, and nitrogen. In the present invention, the capture pressure is preferably 0.8~1.2 atm, more preferably 1 atm; the temperature is preferably 200~400℃, more preferably 250~350℃, more preferably 200℃, 250℃, 300℃, 350℃, or 400℃; the time is preferably 1~10 min, more preferably 5 min. In the present invention, the capture is preferably carried out in a fixed-bed reactor.

[0041] In this invention, during the capture process, CO2 is mainly adsorbed by CaO in the CeNiCa core, forming carbonate species; NO in the flue gas is oxidized to NO2 by O2 under the catalysis of the CeCuMnK composite material; the generated NO2 is selectively adsorbed by K species in the CeCuMnK composite material, forming nitrate / nitrite species. Through the above partitioning, synergistic and non-competitive capture of CO2 and NOx is achieved.

[0042] After obtaining the active material for capturing the gas, the present invention performs in-situ conversion of hydrogen gas through the active material to obtain purified gas. In this invention, prior to the in-situ conversion, the active material for capturing the gas preferably undergoes purging. The gas used for purging is preferably nitrogen, the purging temperature is preferably 200-300°C, more preferably 250°C, and the purging time is preferably 5 minutes. The purging removes weakly adsorbed gases from the pipeline and onto the surface of the active material for capturing the gas. In this invention, the purging is preferably performed in a fixed-bed reactor.

[0043] In this invention, the pressure of the in-situ conversion is preferably 0.8~1.2 atm, more preferably 1 atm; the temperature is preferably 350~650℃, more preferably 400~550℃, more preferably 350℃, 400℃, 450℃, 500℃, 550℃, 600℃ or 650℃; the time is preferably 0.5~1.5h, more preferably 1h. In this invention, the in-situ conversion is preferably carried out in a fixed-bed reactor.

[0044] In this invention, during the in-situ conversion process, the adsorbed carbonate species are reduced by H2 at the Ni active sites of the CeNiCa core, mainly generating CH4. The adsorbed nitrate / nitrite species are selectively catalytically reduced by H2 at the Cu, Mn, and Ce active sites of the CeCuMnK composite material, mainly generating N2. This achieves the resource utilization of CO2 and the purification of NOx, while also enabling the regeneration of the bifunctional material.

[0045] The following detailed description, in conjunction with embodiments, illustrates the CeCuMnK / CeNiCa bifunctional materials, their preparation methods, and applications provided by this invention. However, these descriptions should not be construed as limiting the scope of protection of this invention.

[0046] Example 1: Preparation of CeCuMnK / CeNiCa bifunctional materials Step 1: Preparation of CeNiCa composite powder (sol-gel method) Calcium nitrate, nickel nitrate, and cerium nitrate were weighed out according to the molar ratio of Ca, Ni, and Ce of 1:0.2:0.1. The above metal salts were dissolved in deionized water along with an equal molar amount of citric acid containing the total metal ions. A complexation reaction was carried out by stirring at room temperature (25°C) for 4 hours, followed by evaporation of water in an 80°C water bath to obtain a viscous gel-like substance. This gel-like substance was dried in a 120°C oven for 12 hours to obtain a fluffy, foamy intermediate product. The intermediate product was ground and placed in a muffle furnace, heated to 550°C at a rate of 5°C / min, and calcined for 4 hours. After cooling, the CeNiCa composite powder was obtained.

[0047] Steps: Preparation of CeCuMnK / CeNiCa bifunctional materials (impregnation method): According to the molar ratio of Cu, Mn, Ce, K to Ca of 0.02:0.02:0.02:0.2:1, copper nitrate, manganese nitrate, cerium nitrate and potassium nitrate are weighed out respectively and dissolved in an appropriate amount of deionized water to form an impregnation solution.

[0048] All the CeNiCa composite materials obtained in step 1 were added to the impregnation solution and stirred at room temperature for 12 hours. Subsequently, they were evaporated to dryness in an 80°C water bath to obtain the precursor. The precursor was dried in a 120°C oven for 12 hours, and finally placed in a muffle furnace and calcined at a heating rate of 5°C / min to 550°C for 4 hours. After cooling to room temperature, the target product, CeCuMnK / CeNiCa bifunctional material, was obtained.

[0049] Meanwhile, CeNiCa (molar ratio 1:0.2:0.1), CeK (molar ratio 0.02:0.2), CeCu (molar ratio 0.02:0.02), CeMnK (molar ratio 0.02:0.02:0.2), CeCuK (molar ratio 0.02:0.02:0.2), CeMnK+CeCuK (physical mixture of the two, where the molar ratio of CeMnK is 0.02:0.02:0.2 and the molar ratio of CeCuK is 0.02:0.02:0.2; the molar ratio of CeMnK+CeCuK is 1:1), and CeCuMnK (molar ratio 0.02:0.02:0.02:0.2) were prepared separately for comparative studies.

[0050] Performance testing: The CO2 capture and conversion and NOx synergistic purification performance of CeCuMnK / CeNiCa bifunctional materials were tested.

[0051] Take 0.3g of the CeCuMnK / CeNiCa material prepared in Example 1 and load it into a fixed-bed quartz reaction tube. First, perform pretreatment: at 500℃ and 1 atm, introduce a 50% H2 / N2 mixed gas (total flow rate 320mL / min) and maintain for 1 hour to activate the material and obtain the reduced CeCuMnK / CeNiCa bifunctional material.

[0052] Figure 1 This is a comparison chart of the NOx adsorption and conversion performance of different materials. Figure 2 The graph shows the concentration changes of the main components (CO, CH4, NO, NO2, N2O and NH3) of different materials during the performance test, where (a) CeCuK; (b) CeMnK; and (c) CeCuMnK.

[0053] like Figure 1 As shown, the NOx capture efficiency of the Ce-Ni-Ca system is below 50%, and the N2 selectivity is less than 60%, indicating its limited ability in NOx adsorption and conversion. Comparing CeCuK and CeK reveals that the introduction of Cu significantly improves the NOx adsorption capacity and capture efficiency; however, its N2 selectivity remains poor, still below 50%. Figure 2As shown in (a), CeCuK exhibits a significant NH3 concentration peak, indicating its high selectivity for NH3, which is consistent with its relatively low N2 selectivity. In contrast, comparing CeK and CeMnK, it can be seen that the introduction of Mn can improve N2 selectivity (>85%), but the NOx capture efficiency is still below 60%.

[0054] In addition, such as Figure 2 As shown in (b), a strong transient NO2 peak and significant N2O formation were observed, indicating that the Mn component more readily promotes the oxidation of NO to NO2, but also inhibits NO2 adsorption. Further comparison of the physical mixture (CeCuK+CeMnK) and CeCuMnK revealed that both achieved NOx capture efficiencies exceeding 90%. However, the N2 selectivity of the mixture (CeCuK+CeMnK) remained below 60%, while CeCuMnK exhibited a much higher N2 selectivity (86.3%). Figure 2 As shown in (c), lower NH3 and NO2 concentration peaks can also be observed at this point. This indicates that only by introducing Cu and Mn together into the same material system can excellent performance be achieved.

[0055] XPS analysis was performed on the obtained CeCuMnK / CeNiCa bifunctional material and the reduced CeCuMnK / CeNiCa bifunctional material. The results are as follows: Figures 3-5 As shown, Figure 3 In the image, (a) is the Ni 2p3 / 2 spectrum of the CeCuMnK / CeNiCa bifunctional material before reduction (corresponding to the Combination in (a)) and CeNiCa; (b) is the Mn 2p spectrum of the CeCuMnK / CeNiCa bifunctional material before reduction (corresponding to the Combination in (b)) and CeCuMnK; (c) is the Ni 2p3 / 2 spectrum of the CeCuMnK / CeNiCa bifunctional material after reduction (corresponding to the Combination in (c)) and CeNiCa; and (d) is the Mn 2p spectrum of the CeCuMnK / CeNiCa bifunctional material before reduction (corresponding to the Combination in (d)) and CeCuMnK. Figure 3 As can be seen from (a) and (c), for Combination and CeNiCa, the reduced sample, compared to the unreduced sample, except for Ni... 2+ and Ni 3+ In addition, obvious Ni was also observed. 0The characteristic peaks indicate that under reducing atmosphere, some Ni species were successfully reduced to metallic Ni with methanation activity, which provides the necessary metal active sites for subsequent conversion processes. The composition and trend of the Ni 2p3 / 2 peak of CeCuMnK / CeNiCa are basically the same before and after reduction.

[0056] Figure 3 Figures (b) and (d) also show that in both the fresh and reduced samples, the manganese in CeCuMnK is mainly in the form of Mn. 2+ and Mn 4+ It exists in the form of Mn; while CeCuMnK / CeNiCa (combination) mainly exists in the form of Mn. 2+ and Mn 0 Characterized by its oxidized state, CeCuMnK exhibits superior performance, achieving a NOx capture efficiency of 90.16% and an N2 selectivity of 86.3%. This indicates that its catalytic activity is more closely related to the oxidized state of manganese than to the metallic state of Mn. 0 Although Mn appeared in the combined sample 0 However, in the actual reaction process, because oxygen is always present, Mn 0 It will be oxidized, but this will not affect its performance; it will still maintain good performance.

[0057] Figure 4 In the figures, (a) Cu 2p spectra of CeCuMnK / CeNiCa bifunctional material before reduction (corresponding to the Combination in (a)) and CeCuMnK, (b) Cu 2p spectra of CeCuMnK / CeNiCa bifunctional material after reduction (corresponding to the Combination in (b)) and CeCuMnK, and (c) Cu LMM spectra of CeCuMnK / CeNiCa bifunctional material after reduction (corresponding to the Combination in (c)) and CeCuMnK.

[0058] Figure 5In the image, (a) Ce 3d spectra of CeCuMnK / CeNiCa bifunctional material before reduction (corresponding to Combination in (a)), CeCuMnK and CeNiCa, (b) K 2p spectra of CeCuMnK / CeNiCa bifunctional material before reduction (corresponding to Combination in (b)) and CeCuMnK, (c) Ce 3d spectra of CeCuMnK / CeNiCa bifunctional material after reduction (corresponding to Combination in (c)), CeCuMnK and CeNiCa, and (d) K 2p spectra of CeCuMnK / CeNiCa bifunctional material after reduction (corresponding to Combination in (d)) and CeCuMnK.

[0059] from Figure 4 and Figure 5 It can be seen that Cu is present in the reduced material. 0 / Cu + / Cu 2+ Mixed valence states and Ce 3+ / Ce 4+ The mixed valence states, and Figure 5 Figures (b) and (d) show a significant difference in the K 2p binding energy of the CeCuMnK / CeNiCa bifunctional materials before and after reduction. Compared with the unreduced material, the K 2p peak of the reduced CeCuMnK / CeNiCa shifts towards the direction of higher binding energy, indicating a decrease in the electron density around K and electron loss from K.

[0060] Cyclic performance testing was then conducted at atmospheric pressure (1 atm), specifically including the following steps: (1) Co-capture stage: Reduce the reactor temperature to 250℃ and introduce simulated flue gas (composition: 10% CO2, 500ppm NO, 3% O2, N2 is the balance gas, total flow rate 400mL / min) for 5 minutes.

[0061] (2) Purging stage: Stop the introduction of simulated flue gas, switch to N2 (flow rate 400mL / min), and purge for 5 minutes at 250℃ to remove weakly adsorbed gas on the pipeline and material surface.

[0062] (3) In-situ conversion stage: switch the atmosphere to pure H2 (flow rate 200 mL / min), and raise the reactor temperature from 250℃ to 500℃ at a rate of 10℃ / min, and keep it at 500℃ for 1 hour.

[0063] Repeat steps (1) to (3) above a total of 10 times, and use Fourier transform infrared spectroscopy and mass spectrometry to monitor the composition of the outlet gas online.

[0064] Cyclic performance such as Figure 6 As shown, from Figure 6 It can be seen that after ten cycles, the carbon capture capacity and methane yield remained at approximately 3.2 and 3.1 mmol / g, respectively, with CO2 conversion remaining above 95%. The product selectivity for CH4 remained close to 100%, and increasing the reaction temperature to 500℃ had no significant effect on product selectivity. Regarding NOx capture and catalytic conversion performance, after ten cycles, the NOx capture capacity of the CeCuMnK / CeNiCa sample remained around 140 μmol / g, the NOx capture rate remained above 85%, and the product selectivity for N2 remained above 90%.

[0065] The above performance test results directly demonstrate the feasibility of constructing a novel bifunctional material by loading CeCuMnK onto CeNiCa, and also verify the feasibility of the integrated carbon capture and conversion and NOx synergistic purification technology.

[0066] Comparative Example 1 The difference from Example 1 is that when preparing the CeCuMnK / CeNiCa bifunctional material, the molar ratio of Cu, Mn, Ce, K and Ca is 0.02:0.02:0.02:0.1:1, and the rest is the same as in Example 1.

[0067] The performance testing process is the same as in Example 1.

[0068] Cyclic performance comparison Figure 7 As shown, compared to Example 1, Comparative Example 1 showed improvements in CO2 conversion rate, carbon capture capacity, and NO content. x The capture efficiency was significantly reduced.

[0069] Regarding carbon cycle performance: the CO2 capture capacity of Comparative Example 1 gradually decreased from approximately 4.7 mmol / g to approximately 3.5 mmol / g, and then further to approximately 2.6 mmol / g, while Example 1 maintained a stable capacity of approximately 3.5–4.0 mmol / g; the CH4 yield decreased from approximately 3.1 mmol / g to approximately 2.3 mmol / g, significantly lower than Example 1 (approximately 3.1 mmol / g and essentially stable). In terms of CO2 conversion, Comparative Example 1 fluctuated between approximately 60–90%, while Example 1 consistently maintained above 95%; both examples showed CH4 selectivity close to 100%.

[0070] Regarding NOx capture and catalytic conversion performance: the NOx capture capacity of Comparative Example 1 is about 70~80 μmol / g, which is lower than the stable 140 μmol / g of Example 1; the NOx capture rate decreased from about 50% to 30%, and then rose back to about 40%, which is significantly lower than the stable level of over 85% in Example 1; the N2 selectivity also remained at 90%, which was not significantly different from Example 1.

[0071] Comparative Example 2 The difference from Example 1 is that when preparing the CeCuMnK / CeNiCa bifunctional material, the molar ratio of Cu, Mn, Ce, K and Ca is 0.02:0.02:0.02:0.3:1, and the rest is the same as in Example 1.

[0072] The performance testing process is the same as in Example 1.

[0073] Cyclic performance comparison Figure 8 As shown in the figure. Compared with Example 1, Comparative Example 2 exhibits lower CO2 conversion and CH4 generation capabilities, while its NOx capture rate is significantly insufficient.

[0074] Regarding carbon cycle performance, the CO2 capture capacity of Comparative Example 2 was significantly lower than that of Example 1, only about 1.2~2 mmol / g, while Example 1 could be stably maintained in the range of about 3.2 mmol / g; the CH4 yield was also significantly lower (about 0.5~0.7 mmol / g), far lower than the level of about 3.1 mmol / g in Example 1. In terms of CO2 conversion, Comparative Example 2 was only about 30~50%, significantly lower than Example 1 which consistently maintained above 95%; however, the CH4 selectivity was still close to 100%, consistent with the performance of Example 1.

[0075] In terms of NOx capture and catalytic conversion performance, the NOx capture capacity of Comparative Example 2 is about 120~125 μmol / g, which is lower than that of Example 1, which is stable at about 140 μmol / g; the NOx capture rate is about 60~75%, which is significantly lower than that of Example 1, which has always maintained a level of over 85%; the N2 selectivity remains at about 90%, which is not much different from that of Example 1.

[0076] Comparative Example 3 The difference from Example 1 is that when preparing the CeCuMnK / CeNiCa bifunctional material, the molar ratio of Cu, Mn, Ce, K and Ca is 0.02:0.01:0.02:0.2:1, and the rest is the same as in Example 1.

[0077] The performance testing process is the same as in Example 1.

[0078] Cyclic performance comparison Figure 9 As shown in the figure, compared to Example 1, Comparative Example 3 shows a significant decrease in both CO2 / CH4 synergistic conversion efficiency and NOx capture performance, resulting in weaker overall performance.

[0079] Regarding carbon cycle performance, the CO2 capture capacity of Comparative Example 3 gradually decreased from approximately 4.3 mmol / g to approximately 2.5 mmol / g in the third cycle, while Example 1 maintained a stable capacity of approximately 3.2 mmol / g; the CH4 yield was approximately 1.8–2 mmol / g, generally lower than the approximately 3.1 mmol / g of Example 1. In terms of CO2 conversion, Comparative Example 3 fluctuated only between 40% and 70%, significantly lower than Example 1, which consistently maintained above 95%; however, the CH4 selectivity remained close to 100%, consistent with Example 1.

[0080] In terms of NOx capture and catalytic conversion performance, the NOx capture capacity of Comparative Example 3 is about 105~115 μmol / g, which is lower than the stable 140 μmol / g of Example 1; the NOx capture rate is about 40~70%, which is significantly lower than the stable level of over 85% in Example 1; the N2 selectivity is about 65~75%, which is lower than that of Example 1 overall and the fluctuation is more obvious.

[0081] Comparative Example 4 The difference from Example 1 is that when preparing the CeCuMnK / CeNiCa bifunctional material, the molar ratio of Cu, Mn, Ce, K and Ca is 0.02:0.03:0.02:0.2:1, and the rest is the same as in Example 1.

[0082] The performance testing process is the same as in Example 1.

[0083] Cyclic performance comparison Figure 10 As shown in the figure. Compared to Example 1, Comparative Example 4 exhibits significant CO2 conversion failure and a substantial decrease in NOx capture capacity.

[0084] Regarding carbon cycle performance, Comparative Example 4 showed a significantly lower CH4 yield (approximately 2.2 → 0.9 → 0.8 mmol / g), with a significant decrease in the latter two cycles, while Example 1 maintained a stable yield of approximately 3.1 mmol / g. In terms of CO2 conversion, Comparative Example 4 experienced a sharp drop from approximately 80%, reaching around 20% in the third cycle, far lower than the consistently high efficiency of over 95% maintained by Example 1; however, the CH4 selectivity remained close to 100%, consistent with Example 1.

[0085] In terms of NOx capture and catalytic conversion performance, the NOx capture amount of Comparative Example 4 was only about 25~40 μmol / g, which was significantly lower than the stable level of about 140 μmol / g in Example 1; the NOx capture rate was also extremely low, only about 20%→10%, which was significantly worse than the stable performance of over 85% in Example 1; the N2 selectivity was about 70→90%→82%, which was not only lower than Example 1 but also fluctuated greatly.

[0086] Comparative Example 5 The difference from Example 1 is that when preparing the CeCuMnK / CeNiCa bifunctional material, the molar ratio of Cu, Mn, Ce, K and Ca is 0.01:0.02:0.01:0.1:1, and the rest is the same as in Example 1.

[0087] The performance testing process is the same as in Example 1.

[0088] Cyclic performance comparison Figure 11 As shown. Compared to Example 1, Comparative Example 5, although possessing a certain initial adsorption capacity, has relatively low overall CO2 conversion efficiency and NOx capture efficiency.

[0089] Regarding carbon cycle performance, the CO2 conversion rate of Comparative Example 5 was approximately 60-70%, significantly lower than the 95% of Example 1. The corresponding CH4 yield fluctuated considerably from 3.3 to 2.5 to 2.8 mmol / g, exhibiting poor overall stability. In contrast, the CH4 yield of Example 1 remained consistently around 3.2 mmol / g. However, the CH4 selectivity remained close to 100%, consistent with Example 1.

[0090] In terms of NOx capture and catalytic conversion performance, the NOx capture amount of Comparative Example 5 is about 115~120 μmol / g, which is lower than the stable level of about 140 μmol / g in Example 1; the NOx capture rate is about 60~70%, which is significantly lower than the high level of over 85% maintained in Example 1; the N2 selectivity is maintained at over 90%, which is close to that of Example 1.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A CeCuMnK / CeNiCa bifunctional material, comprising a CeNiCa core and a CeCuMnK composite material loaded on the CeNiCa core; The CeNiCa core comprises calcium oxide, cerium oxide, and nickel oxide; The CeCuMnK composite material includes cerium oxide, copper oxide, manganese oxide, and potassium oxide.

2. The CeCuMnK / CeNiCa bifunctional material according to claim 1, characterized in that, In the CeNiCa core, the molar ratio of cerium, nickel, and calcium is 0.08~0.12:0.18~0.22:

1.

3. The CeCuMnK / CeNiCa bifunctional material according to claim 1 or 2, characterized in that, The molar ratio of cerium in the CeCuMnK composite material to calcium in the CeNiCa core is 0.018~0.022:1; The molar ratio of copper in the CeCuMnK composite material to calcium in the CeNiCa core is 0.018~0.022:1; The molar ratio of manganese in the CeCuMnK composite material to calcium in the CeNiCa core is 0.018~0.022:1; The molar ratio of potassium in the CeCuMnK composite material to calcium in the CeNiCa core is 0.18~0.22:

1.

4. The method for preparing the CeCuMnK / CeNiCa bifunctional material according to any one of claims 1 to 3, characterized in that, Includes the following steps: Provide CeNiCa composite powder; A soluble cerium salt, soluble copper salt, soluble manganese salt, soluble potassium salt, and water are mixed to form an impregnation solution; The CeNiCa composite material powder was added to the impregnation solution, and impregnation and evaporation were performed sequentially to obtain the precursor; The precursor is subjected to a first calcination to obtain the CeCuMnK / CeNiCa bifunctional material.

5. The preparation method according to claim 4, characterized in that, The method for preparing the CeNiCa composite powder includes the following steps: Soluble calcium salt, soluble nickel salt, soluble cerium salt, citric acid and water are mixed and subjected to complexation reaction and evaporation in sequence to obtain a gel-like substance; The gelatinous substance was dried to obtain an intermediate product; The intermediate product is subjected to a second calcination to obtain the CeNiCa composite material powder.

6. The preparation method according to claim 5, characterized in that, In the process of preparing the gel-like substance, the molar ratio of the citric acid to the total molar ratio of the soluble modified, soluble nickel salt and soluble cerium salt is 0.8~1.2:

1.

7. The preparation method according to claim 5 or 6, characterized in that, The complexation reaction is carried out at a temperature of 20-30°C for 3-5 hours. The evaporation temperature is 70~90℃; The drying temperature is 100~150℃, and the time is 10~15h; The second calcination temperature is 500~600℃, the heating rate to the second calcination temperature is 4~6℃ / min, and the time is 3~5h.

8. The preparation method according to claim 4, characterized in that, The first calcination temperature is 500~600℃, the heating rate to the first calcination temperature is 4~6℃ / min, and the time is 3~5h.

9. A method for purifying NOx in flue gas, characterized in that, Includes the following steps: The active material is reduced to obtain a reduced active material; The flue gas to be treated is captured by the reducing active material to obtain the active material for capturing the gas; Hydrogen gas is passed through the active material used to capture the gas for in-situ conversion to obtain purified gas. The active material is the CeCuMnK / CeNiCa bifunctional material according to any one of claims 1 to 3 or the CeCuMnK / CeNiCa bifunctional material prepared by the preparation method according to any one of claims 4 to 8.

10. The purification method according to claim 9, characterized in that, The reduction treatment atmosphere includes nitrogen and hydrogen, with a pressure of 0.8~1.2 atm, a temperature of 350~650℃, and a time of 0.5~1.5h; The trapping pressure is 0.8~1.2 atm, the temperature is 200~400℃, and the time is 1~10 min; The in-situ transformation is carried out at a pressure of 0.8~1.2 atm, a temperature of 350~650℃, and a time of 0.5~1.5h.

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