Preparation method of CeO2-CuNi0. 5Mn1. 5O4 composite catalyst and application of CeO2-CuNi0. 5Mn1. 5O4 composite catalyst in stable CO-SCR denitration in aerobic environment

Abstract

The invention belongs to the technical field of selective catalytic reduction, and particularly relates to a preparation method of a CeO2-CuNi0. 5Mn1. 5O4 composite catalyst and application of the CeO2-CuNi0. 5Mn1. 5O4 composite catalyst in stable CO-SCR denitration in an aerobic environment. The CeO2-CuNi < 0.5 > Mn < 1.5 > O < 4 > composite catalyst synthesized by a solution-gel method can be applied to the field of CO-SCR (selective catalytic reduction). Compared with an existing catalyst, the CeO2-CuNi0. 5Mn1. 5O4 composite catalyst has the advantages that the number of surface active sites is large, richer surface oxygen vacancies are provided, a CeO2 fluorite structure serves as a rigid framework to inhibit spinel phase grain aggregation, spinel phase compact crystal lattices lock metal ions, XRD crystal phases are not obviously changed before and after the reaction, the structural stability is remarkable, and the catalyst is suitable for industrial production. And the catalyst still has excellent CO-SCR performance in an aerobic environment.

Description

Technical Field

[0001] This invention belongs to the field of selective catalytic reduction technology, specifically relating to a CeO2-CuNi 0.5 Mn 1.5 Preparation method of O4 composite catalyst and its application in stabilizing CO-SCR denitrification in an aerobic environment. Background Technology

[0002] Nitrogen oxides (NO) X NO is a major air pollutant emitted from industrial flue gas, vehicle exhaust, and other sources. It not only causes environmental problems such as acid rain and photochemical smog, but also poses serious harm to the human respiratory system. Therefore, NO... X Highly efficient removal of CO has become a key research direction in the environmental protection field. Selective catalytic reduction of NO (CO-SCR) technology can simultaneously oxidize CO and reduce NO (generating harmless N2 and CO2), and is suitable for applications containing CO and NO. X Complex flue gas scenarios with coexistence (such as coke oven gas from steel plants and exhaust gas from internal combustion engines) have become one of the most closely watched denitrification technologies in recent years. However, existing CO-SCR catalysts still face many technical bottlenecks in practical applications. Although noble metal catalysts with Pt, Pd, Rh, etc. as active components have high CO-SCR activity in the medium and low temperature range, precious metal resources are scarce and expensive. Furthermore, they are prone to particle sintering at high temperatures, leading to the loss of active sites. At the same time, they have weak resistance to interference from impurity gases (such as SO2 and H2O), making it difficult to promote their large-scale application. Catalysts with single transition metal oxides such as MnO2, CuO, and NiO as active components are cheaper, but they suffer from a small number of active sites and insufficient surface oxygen vacancy concentration. In the low temperature range (usually <300℃), it is difficult to effectively adsorb and activate NO and CO, resulting in low denitrification efficiency. In the high temperature range (usually >600℃), the catalytic activity is easily reduced due to crystal structure collapse or metal ion migration and aggregation, making them unsuitable for scenarios with wide temperature fluctuations in industrial flue gas. Spinel-structured (AB2O4) transition metal oxides (such as NiMn2O4 and CuMn2O4) have been attempted for CO-SCR reactions due to their good structural stability. However, single spinel catalysts suffer from poor metal component dispersion and insufficient exposure of active sites. Furthermore, in an aerobic atmosphere, O2 easily competes with NO and CO for adsorption active sites, leading to a decrease in NO reduction efficiency. At the same time, they lack the ability to store and release oxygen to assist the reaction cycle, making it difficult to maintain long-term stable catalytic performance. Summary of the Invention

[0003] To address the above problems, this invention provides a CeO2-CuNi 0.5 Mn 1.5Preparation method of O4 composite catalyst and its application in CO-SCR (CO-Selective Catalytic Reduction) denitrification in an aerobic environment.

[0004] The technical solution adopted in this invention is as follows:

[0005] A CeO2-CuNi 0.5 Mn 1.5 The preparation method of O4 composite catalyst includes the following steps:

[0006] 1) Dissolve copper nitrate trihydrate, manganese acetate, nickel acetate, cerium nitrate hexahydrate and citric acid monohydrate in deionized water and stir thoroughly until completely dissolved to obtain a mixed solution;

[0007] 2) Evaporate the solvent in the mixed solution obtained in step 1) to obtain a viscous sol;

[0008] 3) Dry the viscous sol obtained in step 2) to obtain a fluffy dry gel;

[0009] 4) The fluffy dry gel obtained in step 3) is placed in a high-temperature muffle furnace and calcined to obtain CeO2-CuNi. 0.5 Mn 1.5 O4 composite catalyst.

[0010] Furthermore, in the above preparation method, step 1), the stirring method is to use a magnetic stirrer.

[0011] Furthermore, in the above preparation method, in step 1), the amount of copper nitrate trihydrate is 0.9664 g, the amount of manganese acetate is 0.98036 g, the amount of nickel acetate is 0.99544 g, the amount of cerium nitrate hexahydrate is 1.73688 g, the amount of citric acid monohydrate is 4.2028 g, and the amount of deionized water is 30 mL.

[0012] Furthermore, in the above preparation method, in step 2), the solvent evaporation temperature is 80 °C and the time is 4 h.

[0013] Furthermore, in the above preparation method, step 3), the drying temperature is 110 ℃ and the drying time is 10 h.

[0014] Furthermore, in the above preparation method, in step 4), the calcination process is carried out in a muffle furnace at a temperature of 900 °C for 240 min, with a heating rate of 5 °C / min.

[0015] CeO2-CuNi prepared by any of the above methods 0.5 Mn 1.5Application of O4 composite catalyst in stabilizing CO-SCR denitrification in an aerobic environment.

[0016] Furthermore, the above application is carried out using the following method: CeO2-CuNi 0.5 Mn 1.5 The O4 composite catalyst was placed in a quartz glass boat, with powdered alumina at the bottom and CeO2-CuNi on top. 0.5 Mn 1.5 The O4 composite catalyst places a quartz glass boat in the central heating zone of a fixed-bed reactor. The tubular furnace provides the temperature required for the denitrification reaction through programmed temperature control, raising the temperature from room temperature to 800 ℃ at a rate of 5 ℃ / min. The inlet mixed gas consists of NO, CO, N2, and air, and the mixed gas flows through the bed to convert NO.

[0017] Furthermore, in the above-mentioned application, the CeO2-CuNi 0.5 Mn 1.5 The amount of O4 composite catalyst used is 0.3 g.

[0018] Furthermore, in the above applications, the NO flow rate is 7.5 mL / min, the N2 flow rate is 150-170 mL / min, the air flow rate is 15 mL / min, the CO flow rate is 50-75 mL / min, and the denitrification reaction temperature is 580 ℃-800 ℃.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. The sol-gel method used in this invention forms stable chelates with Ce, Cu, Ni, and Mn metal ions using citric acid. The spatial confinement effect of the gel network achieves atomic-level uniform dispersion of the four metal components, effectively inhibiting the aggregation of active metals. This uniform dispersion characteristic significantly increases the Cu content on the catalyst surface. 2+ / Cu + Ni 2+ Mn 3+ / Mn 4+ The number of active sites also induces more cooperative oxygen vacancies in the CeO2 fluorite and spinel phases through lattice interactions between metal ions.

[0021] 2. This invention uses transition metals as active components, and the method is simple, low-cost, and conducive to large-scale production. Furthermore, CeO2 and CuNi... 0.5 Mn 1.5 The dual-phase synergistic effect formed by the O4 spinel phase helps Cu and Mn active sites maintain their active valence state by leveraging Ce's oxygen storage capacity, while Ni enhances the low-temperature adsorption capacity of NO. The multi-metal synergistic effect significantly improves the low-temperature activity of the catalyst.

[0022] 3. The CeO2-CuNi synthesized by the sol-gel method in this invention 0.5 Mn 1.5 The O4 composite catalyst system still exhibits excellent CO-SCR performance in an aerobic environment. Attached Figure Description

[0023] Figure 1 CeO2-CuNi 0.5 Mn 1.5 X-ray diffraction pattern of the O4 composite catalyst.

[0024] Figure 2 CeO2-CuNi 0.5 Mn 1.5 The graph shows the change in NO conversion rate of O4 composite catalyst with temperature and the adjustment of CO gas ratio.

[0025] Figure 3 CeO2-CuNi 0.5 Mn 1.5 Stability diagram of O4 composite catalyst at 800 °C for 3 h. Detailed Implementation

[0026] Example 1

[0027] CeO2-CuNi 0.5 Mn 1.5 The preparation method of O4 composite catalyst is as follows:

[0028] 0.9664 g of copper nitrate trihydrate, 0.98036 g of manganese acetate, 0.99544 g of nickel acetate, 1.73688 g of cerium nitrate hexahydrate, and 4.2028 g of citric acid monohydrate were dissolved in 30 mL of deionized water. After magnetic stirring until homogeneous, the mixture was gradually heated to 80 °C and continuously stirred for 4 h to allow complete evaporation of water, forming a viscous sol. The resulting viscous sol was dried in a forced-air drying oven at 110 °C for 10 h. The dried powder was then transferred to a crucible and calcined in a high-temperature muffle furnace at 900 °C for 240 min, with a heating rate of 5 °C / min, to obtain CeO2-CuNi. 0.5 Mn 1.5 O4 composite catalyst.

[0029] Example 2

[0030] Figure 1 CeO2-CuNi prepared in Example 1 0.5 Mn 1.5X-ray diffraction pattern of the O4 composite catalyst. Characteristic diffraction peaks appear at 2θ = 18.5°, 30.5°, 35.9°, and 37.5°, corresponding to the (111), (220), (311), and (222) crystal planes, respectively. This is consistent with the CuNi... 0.5 Mn 1.5 The O4PDF standard card (PDF#32-0345) is consistent; characteristic diffraction peaks appear in the figure at 2θ = 28.5°, 33.0°, 47.5°, 56.3° and 76.6°, corresponding to the (111), (200), (220), (311) and (331) crystal planes, which is consistent with CuNi 0.5 Mn 1.5 Consistent with the O4PDF standard card (PDF#34-0394). From Figure 1 As can be seen from this, CeO2-CuNi 0.5 Mn 1.5 O4 composite catalyst was successfully prepared.

[0031] Example 3

[0032] The catalyst activity was evaluated in an atmospheric pressure fixed-bed reactor, which mainly consisted of a gas supply section, a gas mixing section, a fixed-bed reactor, and an analyzer. The quartz tube used in the reaction was 120 cm long and 11 mm in inner diameter, and a horizontal tube furnace was employed for programmed temperature rise. CeO2-CuNi 0.5 Mn 1.5 The O4 composite catalyst was placed in a quartz glass boat (50 mm long, 10 mm wide, and 5 mm high), with powdered alumina at the bottom and 0.3 g of CeO2-CuNi on top. 0.5 Mn 1.5 An O4 composite catalyst was used, with a quartz glass boat placed in the central heating zone of a fixed-bed reactor. A tubular furnace provided the required temperature for the denitrification reaction via programmed temperature control, with a heating rate set at 5 °C / min. The simulated flue gas composition was NO (7.5 mL / min, 4008 ppm nitrogen mixture), CO (50-75 mL / min, 5% argon mixture), and a mixture of N2 (150-170 mL / min) as the balance gas and air (15 mL / min). The inlet and outlet concentrations of NO were quantitatively analyzed online using a Thermo Model 42i nitrogen oxide analyzer. The reactor was heated from room temperature to 800 °C at a rate of 5 °C / min using programmed temperature control. The performance of the denitrification catalyst was measured by the NO conversion rate (Q) flowing through the bed. NO The measurement is based on the formula:

[0033]

[0034] In the formula: [ NO ] in For the inlet concentration of NO, [ NO ] out This represents the outlet concentration of NO. Both are recorded after the NO concentration reaches a stable value.

[0035] Figure 2 The graph shows the NO conversion rate of the sample as a function of temperature and the adjustment of the CO gas ratio. It can be seen that when the CO gas flow rate is 50 mL / min, the NO conversion rate reaches 99.9% at 640 ℃; when the CO gas flow rate is 75 mL / min, the NO conversion rate reaches 99.9% at 580 ℃.

[0036] Example 4

[0037] Figure 3 CeO2-CuNi 0.5 Mn 1.5 The stability curve of the O4 composite catalyst for CO-SCR denitration at 800 ℃ for 3 hours is shown in the figure. As can be seen from the figure, under simulated industrial extreme high-temperature long-term operating conditions, the CeO2-CuNi... 0.5 Mn 1.5 The NO conversion rate of the O4 composite catalyst remained stable in the range of 99.97% to 99.99%, with no significant downward trend throughout the process, and only a slight fluctuation of ±0.1%, demonstrating its resistance to high-temperature degradation.

Claims

1. A CeO2-CuNi 0.5 Mn 1.5 O4 composite catalyst, characterized by, The method comprises the following steps: 1) dissolving copper nitrate trihydrate, manganese acetate, nickel acetate, cerium nitrate hexahydrate and citric acid monohydrate in deionized water, stirring thoroughly until completely dissolved to obtain a mixed solution; 2) performing solvent evaporation on the mixed solution obtained in step 1) to obtain a viscous sol; 3) drying the viscous sol obtained in step 2) to obtain a fluffy dry gel; 4) The fluffy dry gel obtained in step 3) is calcined in a high temperature muffle furnace to obtain CeO2-CuNi 0.5 Mn 1.5 O4 composite catalyst.

2. The production method according to claim 1, characterized by, In step 1), the stirring is performed by using a magnetic stirrer.

3. The preparation method according to claim 1, characterized in that, In step 1), the amount of copper nitrate trihydrate is 0.9664 g, the amount of manganese acetate is 0.98036 g, the amount of nickel acetate is 0.99544 g, the amount of cerium nitrate hexahydrate is 1.73688 g, the amount of citric acid monohydrate is 4.2028 g, and the amount of deionized water is 30 mL.

4. The method of claim 1, wherein, In step 2), the solvent evaporation temperature is 80°C, and the time is 4 h.

5. The preparation method according to claim 1, characterized in that, In step 3), the drying temperature is 110°C, and the drying time is 10 h.

6. The method of claim 1, wherein, In step 4), the calcination process is performed in a muffle furnace, the calcination temperature is 900°C, the time is 240 min, and the heating rate is 5°C / min.

7. The CeO2-CuNi prepared by the preparation method of any one of claims 1-6 0.5 Mn 1.5 Application of the CeO2-CuNi composite catalyst in the stable CO-SCR denitration in the aerobic environment.

8. Use according to claim 7, characterized in that, The method is as follows: CeO2-CuNi 0.5 Mn 1.5 O4 composite catalyst is placed in a quartz glass boat, the bottom is padded with powdered alumina, and the top is paved with CeO2-CuNi 0.5 Mn 1.5 O4 composite catalyst, and the quartz glass boat is placed in the middle heating zone of the fixed bed reactor. The tube furnace provides the temperature required for the denitration reaction through program-controlled temperature, and the temperature is increased from room temperature to 800 ℃ at a rate of 5 ℃ / min. The mixed gas components of the inlet gas are: NO, CO, N2 and air, and the mixed gas flows through the bed layer to convert NO.

9. Use according to claim 8, characterized in that, The CeO2-CuNi 0.5 Mn 1.5 The amount of the CeO2-CuNi 0.3 g.

10. Use according to claim 8, characterized in that, The NO flow rate is 7.5 mL / min, the N2 flow rate is 150-170 mL / min, the air flow rate is 15 mL / min, the CO flow rate is 50-75 mL / min, and the denitration reaction temperature is 580-800°C.

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