A n2o decomposition catalyst using waste rare earth-based denitration catalyst as raw material and a preparation method thereof

Abstract

The application discloses a N2O decomposition catalyst taking waste and old rare earth-based denitration catalyst as raw material and a preparation method thereof, and the catalyst is prepared from the waste and old rare earth-based denitration catalyst, diatomite and kaolin as a N2O decomposition catalyst carrier, and a nickel-lanthanum composite oxide (NiLaO x ) as a catalytically active component. The waste and old rare earth-based denitration catalyst, diatomite and kaolin are prepared into the carrier through crushing, batching and calcining processes, a nickel-lanthanum composite oxide precursor is configured into a colloidal solution, then the carrier is immersed in the nickel-lanthanum composite oxide precursor colloidal solution, and the N2O decomposition catalyst is obtained through drying and calcining. The catalyst not only realizes harmless disposal of the waste and old rare earth-based denitration catalyst, but also uses the waste and old rare earth-based denitration catalyst as a high-value resource for N2O decomposition, and the catalyst has high N2O decomposition activity and strong stability.

Description

TECHNICAL FIELD

[0001] The application provides an N2O decomposition catalyst taking a waste rare earth-based denitration catalyst as a raw material and a preparation method thereof, and belongs to the fields of waste product resourceization, environmental protection catalyst materials and atmospheric pollution treatment. BACKGROUND

[0002] Nitrous oxide (N2O) is an important greenhouse gas and has a serious destructive effect on the ozone layer. N2O mainly comes from the synthesis of adipic acid and nitric acid, the combustion of fossil fuels and the like, can be stored for about 120 years, and the influence of N2O on the earth's radiation balance is only second to CO2 and CH4, about 10-15% of the influence of CO2. Although N2O is not the main factor of global warming, its global warming potential (GWP) is 310 times that of CO2, and its contribution to the greenhouse effect of the earth is 2.5 times that of CH4. It also participates in many photochemical reactions in the atmosphere to generate secondary pollutants. With the enhancement of people's environmental protection consciousness, the development of N2O elimination technology has attracted global attention. The N2O catalytic decomposition technology has the advantages of simple operation process, low cost and no secondary pollution to the environment, and is the most economical and environmentally efficient N2O emission reduction method. The core of the technology is the N2O decomposition catalyst.

[0003] In the related technology of the existing N2O decomposition catalyst, the patents (CN108144616A, CN107233892A and CN107233892A) all use metal oxides themselves as catalysts to catalytically decompose N2O. This method has low utilization rate of metal oxides and high cost of catalysts, which limits the practical application of the catalysts. The patents (CN 104888767 A, CN 103157466A and CN107233892A) use noble metals as active components, which have high cost. The patent (CN 112755780A) discloses a nanocomposite material coated with carbon and nickel as an N2O decomposition catalyst. The nanocomposite material has a core-shell structure with a shell layer and a core. The shell layer is a graphitized carbon layer, and the core is a nickel nanoparticle. The catalyst has excellent N2O decomposition activity. The patent (CN103752335A) discloses a synthesis method of Fe2O3 / Silicalite-1 molecular sieve nanowires for N2O decomposition. The invention uses Fe2O3 / SiO2 as a precursor, ethylenediamine and triethylamine as a template agent, and a hydrothermal crystallization method to synthesize Fe2O3 / Silicalite-1 nanowires with MFI structure, which has good activity for N2O decomposition. However, the preparation methods of the above two patents are relatively complex and are not suitable for industrial large-scale application.

[0004] In view of the lack of domestic N2O removal catalyst development and application, developing a low-cost, excellent activity, simple preparation process, and suitable for industrial large-scale application of N2O decomposition catalyst is the research focus. In addition, the Environmental Protection Network issued the "Notice on Strengthening the Supervision of Waste Flue Gas Denitrification Catalysts", which includes the management, regeneration, and utilization of waste flue gas denitrification catalysts in the hazardous waste management, and requires to improve the regeneration and utilization disposal capacity. Therefore, the regeneration treatment or resource utilization of waste and old rare earth-based catalysts has become an urgent environmental protection problem to be solved. The main component of the waste and old rare earth-based catalyst is titanium dioxide carrier with large specific surface area and excellent water and sulfur resistance, and the active components (Ce, W, etc.) provide excellent oxidation and reduction performance and rich surface acidity, which is beneficial to promote the N2O decomposition reaction. The abundant pore structure and large specific surface area of diatomite can better disperse the active components. The addition of kaolin can better form the catalyst and improve the mechanical strength of the catalyst. Nickel oxide has good activity and selectivity for N2O decomposition, and the addition of lanthanum oxide can prepare nickel lanthanum composite oxide with stronger interaction, effectively improve the effective specific surface area, surface oxygen species concentration and oxidation and reduction performance of the catalyst, further improve the N2O decomposition activity and selectivity, improve the stability of the active component and reduce the amount of the active component, and reduce the cost. The successful application of the invention not only solves the problem of treatment of waste and old rare earth-based denitrification catalysts, but also better solves the N2O pollution problem as an N2O decomposition catalyst, reduces the use cost of the N2O decomposition catalyst, and thus brings huge economic, environmental and social benefits. SUMMARY

[0005] The purpose of the present application is to provide a N2O decomposition catalyst using waste and old rare earth-based catalyst as raw material, to solve the problem of resource treatment of waste catalyst. Another purpose of the present application is to provide a preparation method of a N2O decomposition catalyst with low cost, excellent activity, simple preparation process and suitable for industrial large-scale application in view of the current situation and existing problems of existing N2O decomposition catalysts.

[0006] The specific technical scheme of the present application is:

[0007] A N2O decomposition catalyst using waste and old rare earth-based denitrification catalyst as raw material and a preparation method thereof, characterized in that the catalyst is prepared by compounding waste and old rare earth-based denitrification catalyst, diatomite and kaolin to prepare a N2O decomposition catalyst carrier, and nickel lanthanum composite oxide (NiLaO x ) as a catalytically active component. The mass ratio of waste and old rare earth-based denitrification catalyst, diatomite and kaolin is 1:(0.6-1.2):(0.05-0.1); the molar ratio of Ni:La elements is 1:(0.1-1); and the mass ratio of the carrier to the catalytically active component is 1:(0.05-0.12).

[0008] The waste and old rare earth-based denitration catalyst is a commercial cerium-based denitration catalyst after use, and the content of the active component CeO2 is 5%-10% based on the carrier TiO2, and the content of the cocatalyst is 5%-10% of WO3 and 1%-5% of ZrO2.

[0009] The preparation steps of the catalyst are as follows:

[0010] (1) Preparation of the carrier

[0011] After the waste and old rare earth-based denitration catalyst, diatomite and kaolin are crushed and sieved, a certain amount of the waste and old rare earth-based denitration catalyst powder, diatomite powder and kaolin powder and a proper amount of deionized water are weighed and placed in the same container, and the mixture is stirred at 60-90°C for 1-2h to obtain a solid mixture; the mixture is filtered, dried and calcined to obtain the catalyst carrier.

[0012] (2) Preparation of the active component colloidal solution

[0013] According to the molar ratio of Ni:La elements being 1:(0.1-1) and the mass ratio of the total mass of the metal salt to the mass of the complexing agent being 1:(0.8-1.2), a certain amount of nickel salt, lanthanum salt, complexing agent and a proper amount of deionized water are weighed and placed in the same container, and the mixture is continuously stirred at 60-90°C for 2-4h until the solution is clear and transparent to obtain the active component colloidal solution.

[0014] (3) Preparation of the catalyst

[0015] According to the mass ratio of the carrier to the catalytically active component being 1:(0.05-0.12), the catalyst carrier prepared in step (1) is immersed in the active component colloidal solution prepared in step (2) for 6-12h, and the immersed catalyst carrier is taken out, dried and calcined to obtain the N2O decomposition catalyst.

[0016] Preferably, the drying temperature in step (1) is 60-90°C, and the drying time is 6-12h; the calcination temperature is 750-900°C, and the holding time is 2-4h.

[0017] Preferably, the nickel salt in step (2) is nickel nitrate or nickel acetate, the lanthanum salt is lanthanum nitrate or lanthanum acetate, and the complexing agent is monohydrate citric acid or ethylenediaminetetraacetic acid.

[0018] Preferably, the drying temperature in step (3) is 60-90°C, the drying time is 6-12h, the calcination temperature is 350-550°C, and the holding time is 2-4h.

[0019] Advantages:

[0020] The catalyst of the present application is suitable for catalytic decomposition of N2O, and the conversion rate of N2O is >90% at 400℃. The catalyst is prepared by compounding waste rare earth-based denitration catalyst, diatomite and kaolin to prepare a N2O decomposition catalyst carrier, and nickel lanthanum composite oxide (NiLaO x ) as a catalytically active component. The main component of the waste rare earth-based catalyst is titanium dioxide carrier with large specific surface area and excellent water and sulfur resistance, and the active components (Ce, W, etc.) provide excellent redox performance and rich surface acidity, which is beneficial to promote the N2O decomposition reaction. The abundant pore structure and large specific surface area of diatomite can better disperse the active component. The addition of kaolin can better shape the catalyst and improve the mechanical strength of the catalyst. Nickel oxide has good activity and selectivity for N2O decomposition, and the addition of lanthanum oxide can prepare nickel lanthanum composite oxide with stronger interaction, effectively improve the effective specific surface area, surface oxygen species concentration and redox performance of the catalyst, further improve the N2O decomposition activity and selectivity, improve the stability of the active component and reduce the amount of the active component, and reduce the cost. Compared with the existing N2O decomposition catalyst, the catalyst of the present application has low cost, excellent activity, simple preparation process, is suitable for industrial large-scale application, effectively solves the problem of treatment of waste rare earth-based denitration catalyst, and has great economic, environmental and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 N2O conversion performance chart of the N2O decomposition catalyst prepared for Examples 1-5. DETAILED DESCRIPTION

[0022] The present application will be further described below in conjunction with examples, but the scope of protection of the present application is not limited thereto.

[0023] The denitration performance evaluation method of the catalyst of the present application is as follows: the N2O inlet concentration is 5000ppm, N2 is used as the carrier gas, and the total gas flow is 1000mL / min. The N2O catalytic decomposition reaction is carried out in a fixed bed reaction system, 3mL of catalyst with a particle size of 40-60 mesh is measured and loaded into a quartz tube reactor with an inner diameter of 10mm, the reaction space velocity (GHSV) is set to 20000h -1 , the reaction temperature range is set to 250-450℃, and a flue gas analyzer is used to monitor the concentration change of N2O before and after the reaction.

[0024] The waste rare earth-based denitration catalyst is a commercial cerium-based denitration catalyst after use, and the active component thereof is CeO2(8%), the cocatalyst is WO3(7%) and ZrO2(3%), the carrier is TiO2, and the rest is an additive.

[0025] Example 1

[0026] (1) Preparation of the carrier

[0027] 10 g of waste rare earth-based denitration catalyst powder, 6 g of diatomite powder, 0.5 g of kaolin powder and 100 g of deionized water were placed in the same container and stirred at 60°C for 1 h to obtain a solid mixture; the mixture was filtered, dried at 60°C for 6 h, calcined at 750°C for 2 h to obtain the catalyst carrier.

[0028] (2) Preparation of the active component colloidal solution

[0029] According to the molar ratio of Ni:La elements being 1:0.1 and the mass ratio of the total mass of nickel salt and lanthanum salt to the mass of monohydrate citric acid being 1:0.8, 1.67 g of nickel nitrate, 0.29 g of lanthanum nitrate, 1.57 g of monohydrate citric acid and 50 g of deionized water were placed in the same container and continuously stirred at 60°C for 2 h until the solution was clear and transparent to obtain the active component colloidal solution.

[0030] (3) Preparation of the catalyst

[0031] According to the mass ratio of the carrier to the catalytically active component being 1:0.05, the catalyst carrier prepared in step (1) was immersed in the active component colloidal solution prepared in step (2) for 6 h, and the immersed catalyst carrier was dried at 60°C for 6 h and calcined at 350°C for 2 h to prepare the N2O decomposition catalyst.

[0032] (4) Evaluation of the performance of the catalyst

[0033] See Figure 1 .

[0034] Example 2

[0035] (1) Preparation of the carrier

[0036] After the waste rare earth-based denitration catalyst, diatomite and kaolin were crushed and sieved, 10 g of waste rare earth-based denitration catalyst powder, 6 g of diatomite powder, 0.5 g of kaolin powder and 100 g of deionized water were placed in the same container according to the mass ratio of waste rare earth-based denitration catalyst: diatomite: kaolin being 1:0.6:0.05 and the mass ratio of waste rare earth-based denitration catalyst to deionized water being 1:10, and stirred at 60°C for 1 h to obtain a solid mixture; the mixture was filtered, dried at 60°C for 6 h and calcined at 750°C for 2 h to obtain the catalyst carrier.

[0037] (2) Preparation of the active component colloidal solution

[0038] According to the molar ratio of Ni:La elements is 1:0.1, the total mass of nickel salt and lanthanum salt / deionized water is 1:0.8, 1.60 g of nickel acetate, 0.29 g of lanthanum acetate, 1.51 g of ethylenediaminetetraacetic acid and 50 g of deionized water are weighed into the same container, and continuously stirred at 60°C for 2 h until the solution is clear and transparent, to obtain the active component colloidal solution.

[0039] (3) Catalyst preparation

[0040] According to the mass ratio of carrier: catalytically active component is 1:0.05, the catalyst carrier prepared in step (1) is immersed in the active component colloidal solution prepared in step (2) for 6 h, and the immersed catalyst carrier is dried at 60°C for 6 h and calcined at 350°C for 2 h to prepare the N2O decomposition catalyst.

[0041] (4) Catalyst performance evaluation

[0042] See Figure 1 .

[0043] Example 3:

[0044] (1) Preparation of carrier

[0045] After the waste rare earth-based denitration catalyst, diatomite and kaolin are crushed and sieved, according to the mass ratio of waste rare earth-based denitration catalyst: diatomite: kaolin is 1:1.2:0.1, the mass ratio of waste rare earth-based denitration catalyst: deionized water is 1:10, 10 g of waste rare earth-based denitration catalyst powder, 12 g of diatomite powder, 1 g of kaolin powder and 100 g of deionized water are weighed into the same container, and stirred at 60°C for 1 h to obtain a solid mixture; the mixture is filtered, dried at 60°C for 6 h and calcined at 750°C for 2 h to obtain the catalyst carrier.

[0046] (2) Preparation of active component colloidal solution

[0047] According to the molar ratio of Ni:La elements is 1:0.25, the total mass of nickel salt and lanthanum salt / ethylenediaminetetraacetic acid is 1:1.2, 4.22 g of nickel acetate, 1.89 g of lanthanum acetate, 7.33 g of ethylenediaminetetraacetic acid and 50 g of deionized water are weighed into the same container, and continuously stirred at 60°C for 2 h until the solution is clear and transparent, to obtain the active component colloidal solution.

[0048] (3) Catalyst preparation

[0049] According to the mass ratio of carrier: catalytically active component is 1:0.12, the catalyst carrier prepared in step (1) is immersed in the active component colloidal solution prepared in step (2) for 6 h, and the immersed catalyst carrier is dried at 60°C for 6 h and calcined at 400°C for 2 h to prepare the N2O decomposition catalyst.

[0050] (4) Catalyst performance evaluation

[0051] See Figure 1 .

[0052] Example 4:

[0053] (1) Preparation of the carrier

[0054] The waste rare earth-based denitration catalyst, diatomite and kaolin were crushed and sieved, and then 10 g of the waste rare earth-based denitration catalyst powder, 12 g of diatomite powder, 1 g of kaolin powder and 100 g of deionized water were weighed out in a same container according to a mass ratio of the waste rare earth-based denitration catalyst: diatomite: kaolin of 1:1.2:0.1 and a mass ratio of the waste rare earth-based denitration catalyst: deionized water of 1:10, and stirred at 60°C for 1 h to obtain a solid mixture; the mixture was filtered, dried at 60°C for 6 h and calcined at 750°C for 2 h to obtain the catalyst carrier.

[0055] (2) Preparation of the active component colloidal solution

[0056] According to a molar ratio of Ni: La elements of 1:1 and a total mass of the nickel salt and the lanthanum salt / deionized water of 1:1.2, 2.06 g of nickel acetate, 3.67 g of lanthanum acetate, 6.88 g of ethylenediaminetetraacetic acid and 50 g of deionized water were weighed out in a same container and continuously stirred at 60°C for 2 h until the solution was clear and transparent to obtain the active component colloidal solution.

[0057] (3) Catalyst preparation

[0058] According to a mass ratio of the carrier: catalytically active component of 1:0.12, the catalyst carrier prepared in step (1) was immersed in the active component colloidal solution prepared in step (2) for 6 h, and the immersed catalyst carrier was taken out, dried at 60°C for 6 h and calcined at 400°C for 2 h to prepare the N2O decomposition catalyst.

[0059] (4) Catalyst performance evaluation

[0060] See Figure 1 .

[0061] Example 5:

[0062] (1) Preparation of the carrier

[0063] The waste and old rare earth-based denitration catalyst, diatomite and kaolin are crushed and sieved, then 10 g of waste and old rare earth-based denitration catalyst powder, 12 g of diatomite powder, 1 g of kaolin powder and 100 g of deionized water are weighed according to the mass ratio of waste and old rare earth-based denitration catalyst: diatomite: kaolin of 1:1.2:0.1 and the mass ratio of waste and old rare earth-based denitration catalyst: deionized water of 1:10, and are placed in the same container, and stirred at 90°C for 2h to obtain a solid mixture; the mixture is filtered, dried at 90°C for 12h, and calcined at 900°C for 4h to obtain a catalyst carrier.

[0064] (2) Preparation of active component colloidal solution

[0065] According to the molar ratio of Ni: La elements of 1:1 and the total mass of nickel salt and lanthanum salt / deionized water of 1:1.2, 2.06 g of nickel acetate, 3.67 g of lanthanum acetate, 6.88 g of ethylenediaminetetraacetic acid and 50 g of deionized water are weighed and placed in the same container, and stirred at 90°C for 4h until the solution is clear and transparent, to obtain an active component colloidal solution.

[0066] (3) Catalyst preparation

[0067] According to the mass ratio of carrier: catalytically active component of 1:0.12, the catalyst carrier prepared in step (1) is immersed in the active component colloidal solution prepared in step (2) for 12h, and the immersed catalyst carrier is taken out, dried at 90°C for 12h, and calcined at 550°C for 4h to prepare a N2O decomposition catalyst.

[0068] (4) Catalyst performance evaluation

[0069] See Figure 1 .

Claims

1. The use of a N2O decomposition catalyst in the catalytic decomposition of N2O, which is prepared from a waste rare earth-based denitration catalyst, characterized in that, The catalyst is prepared by using waste rare earth-based denitration catalyst, diatomite and kaolin as a carrier and using nickel-lanthanum composite oxide as a catalytically active component; The mass ratio of the waste rare earth-based denitration catalyst, diatomite and kaolin in the carrier is 1:(0.6-1.2):(0.05-0.1); the molar ratio of Ni:La elements in the nickel-lanthanum composite oxide is 1:(0.1-1); and the mass ratio of the carrier to the catalytically active component is 1:(0.05-0.12). In the waste rare earth-based denitration catalyst, the content of the active component CeO2 is 5%-10% and the content of the cocatalyst is 5%-10% WO3 and 1%-5% ZrO2 based on the carrier TiO2.

2. Use according to claim 1, characterized in that, The preparation steps of the N2O decomposition catalyst are as follows: (1) Preparation of the carrier The waste rare earth-based denitration catalyst powder, diatomite powder, kaolin powder and deionized water are mixed and stirred at 60-90 ℃ for 1-2 h to obtain a solid mixture; the mixture is filtered, dried and calcined to obtain the catalyst carrier; (2) Preparation of the active component colloidal solution The nickel salt, lanthanum salt, complexing agent and deionized water are weighed into the same container according to the molar ratio of Ni:La elements being 1:(0.1-1) and the mass ratio of the total mass of the metal salt to the mass of the complexing agent being 1:(0.8-1.2), and continuously stirred at 60-90 ℃ for 2-4 h until the solution is clear and transparent to obtain the active component colloidal solution; (3) Preparation of the catalyst The catalyst carrier prepared in step (1) is immersed in the active component colloidal solution prepared in step (2) for 6-12 h according to the mass ratio of the carrier to the catalytically active component being 1:(0.05-0.12), and the immersed catalyst carrier is taken out, dried and calcined to obtain the N2O decomposition catalyst.

3. Use according to claim 2, characterized in that, In step (1), the drying temperature is 60-90 ℃, and the drying time is 6-12 h; the calcination temperature is 750-900 ℃, and the calcination time is 2-4 h.

4. Use according to claim 2, characterized in that, In step (2), the nickel salt is nickel nitrate or nickel acetate, the lanthanum salt is lanthanum nitrate or lanthanum acetate, and the complexing agent is citric acid monohydrate or ethylenediaminetetraacetic acid.

5. Use according to claim 2, characterized in that, In step (3), the drying temperature is 60-90 ℃, the drying time is 6-12 h, the calcination temperature is 350-550 ℃, and the calcination time is 2-4 h.

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