Ru / Ce0. 3Zr0. 7O2-F catalyst for methane catalytic combustion as well as preparation method and application of Ru / Ce0. 3Zr0. 7O2-F catalyst

Abstract

The invention discloses a Ru / Ce0. 3Zr0. 7O2-F catalyst for a methane catalytic combustion reaction and a preparation method of the Ru / Ce0. 3Zr0. 7O2-F catalyst. The catalyst comprises the following components in percentage by weight: 1.0 percent of Ru, 0.3 percent of Ce, 0.7 percent of Zr, 99.0 percent of O2-F. The catalyst is prepared by adopting an oxidation coprecipitation-acid etching-impregnation method. The catalyst provided by the invention can completely oxidize methane into carbon dioxide and water at a relatively low reaction temperature, so that up-to-standard emission of methane waste gas is realized, byproducts with greater pollution are not generated, and secondary pollution is avoided. The Ru / Ce0. 3Zr0. 7O2-F catalyst is prepared by adopting an oxidation coprecipitation-acid etching-impregnation method, the activity of the catalyst can be remarkably improved, meanwhile, the preparation method is simple and easy to implement, and industrialization is easy to realize.

Description

Technical Field

[0001] The present invention relates to the technical field of methane catalytic combustion, and in particular to a Ru / Ce 0.3 Zr 0.7 O2-F catalyst and preparation method thereof. Background Art

[0002] As global concerns about climate change increase, the International Maritime Organization (IMO) has implemented stricter emission standards to reduce the impact of shipping on the environment. Liquefied natural gas (LNG), as a ship fuel, is considered an effective alternative to traditional heavy fuel oil due to its lower carbon emissions and almost sulfur-free characteristics. However, methane escape may occur during the operation of LNG ships. Methane is a greenhouse gas that is more powerful than carbon dioxide, and its 20-year global warming potential (GWP) is 82 times that of carbon dioxide. Therefore, methane escape from LNG ships needs to be effectively purified. Methane catalytic combustion has the advantages of low reaction temperature, high purification efficiency, and no secondary pollution. It has a good development prospect. The key is the development of high-performance purification catalysts.

[0003] The catalysts currently used for catalytic combustion of methane include supported precious metal catalysts, mixed oxide catalysts and molecular sieve catalysts, among which supported precious metal catalysts show good methane catalytic combustion performance. Cerium-zirconium solid solution has good redox performance. The material can be prepared by a simple oxidation coprecipitation method, and the surface of the cerium-zirconium solid solution can be etched by a suitable acid to further improve its redox performance. The related catalysts obtained by loading Ru on cerium-zirconium solid solution show good catalytic activity in other catalytic combustion reactions. For example, CN117138779A discloses a Ru@Ce with a Ru loading of 0.1-2.0% for catalytic combustion of vinyl chloride. x Zr 1-x O2 catalyst. However, there is relatively little research on this catalyst in the field of methane catalytic combustion.

[0004] Based on this, the present invention provides a Ru / Ce 0.3 Zr 0.7 The invention discloses a method for preparing an O2-F catalyst. The catalyst prepared by the method has good methane catalytic combustion activity. Summary of the invention

[0005] The purpose of the present invention is to provide a high performance Ru / Ce catalyst for methane catalytic combustion reaction. 0.3 Zr 0.7 O2-F catalyst and preparation method thereof.

[0006] The Ru / Ce catalyst for methane catalytic combustion reaction of the present invention0.3 Zr 0.7 The composition and weight percentage content of the O2-F catalyst are:

[0007] Ru 1.0%,

[0008] Ce 0.3 Zr 0.7 O2-F 99.0%.

[0009] The Ru / Ce catalyst for methane catalytic combustion reaction of the present invention 0.3 Zr 0.7 The preparation method of O2-F catalyst is prepared by oxidation coprecipitation-acid etching-impregnation method, comprising the following steps:

[0010] (1) Dissolve cerium nitrate and zirconium oxynitrate in deionized water at a molar ratio of cerium to zirconium of 3:7, then dropwise add hydrogen peroxide to 3+ Oxidation to Ce 4+ ; Then add ammonia water to adjust the pH to 8-9, so that Ce 4+ With Zr 4+ Complete co-precipitation; the obtained precipitate is washed to neutrality, then dried and calcined to obtain Ce 0.3 Zr 0.7 O2 carrier;

[0011] (2) Ce 0.3 Zr 0.7 The O2 carrier is dispersed in HF solution, acid-etched, washed to neutrality, dried, and calcined to obtain Ce. 0.3 Zr 0.7 O2-F carrier;

[0012] (3) Ce 0.3 Zr 0.7 The O2-F carrier was dispersed in deionized water, and a ruthenium chloride aqueous solution was added dropwise under stirring to load ruthenium chloride on Ce. 0.3 Zr 0.7 O2-F carrier, then washed to neutral, dried and calcined to obtain Ru / Ce 0.3 Zr 0.7 O2-F catalyst; wherein the amount of ruthenium trichloride aqueous solution added should be controlled so that the Ru loading in the catalyst after calcination is 1wt.%.

[0013] According to a specific embodiment of the present invention, in step (1), stirring is continued for 2 hours after the ammonia water is added dropwise to ensure that the coprecipitation reaction is complete.

[0014] The concentration of the ammonia water is not particularly limited in the present invention, and any concentration of commercially available ammonia water can be used. According to a specific embodiment of the present invention, the concentration of the ammonia water is 28 wt.%.

[0015] The drying in step (1) can be carried out by vacuum drying, heating drying and other methods, which are not particularly limited in the present invention. According to a specific embodiment of the present invention, in step (1), the drying temperature is 120°C.

[0016] The calcination temperature in step (1) is 400-600°C. In this temperature range, the calcination time is preferably 2-6 hours. According to a specific embodiment of the present invention, in step (1), the calcination temperature is 500°C.

[0017] According to a specific embodiment of the present invention, in step (2), Ce 0.3 Zr 0.7 The O2 carrier is dispersed in the HF solution and ultrasonically stirred to enhance the acid etching effect. The ultrasonic stirring time is preferably 10 minutes.

[0018] The drying in step (2) can be carried out by vacuum drying, heating drying and other methods, which are not particularly limited in the present invention. According to a specific embodiment of the present invention, in step (2), the drying temperature is 120°C.

[0019] The calcination temperature in step (2) is 400-600° C. In this temperature range, the calcination time is preferably 2 to 6 hours. According to a specific embodiment of the present invention, in step (2), the calcination temperature is 500° C.

[0020] According to a specific embodiment of the present invention, in order to further ensure that ruthenium trichloride is loaded on Ce 0.3 Zr 0.7 On the O2-F carrier, in step (3), after adding the ruthenium trichloride aqueous solution dropwise under stirring, continue stirring for a period of time. Preferably, continue stirring for 1 to 2 hours. The drying described in step (3) can be carried out in a variety of ways such as vacuum drying and heating drying, which are not particularly limited in the present invention. According to a specific embodiment of the present invention, in step (3), the drying temperature is 120°C.

[0021] The calcination temperature in step (3) is 400-600°C. In this temperature range, the calcination time is preferably 2-6 hours. According to a specific embodiment of the present invention, in step (3), the calcination temperature is 500°C.

[0022] The Ru / Ce 0.3 Zr 0.7 O2-F catalyst is used for catalytic combustion of methane.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] One of the significant advantages of the catalyst of the present invention is that hydrofluoric acid (HF) etching can increase the roughness of the carrier surface and expose oxygen vacancies, so that Ru and the carrier form a strong interaction, while stabilizing Ru and increasing the redox performance of the catalyst.

[0025] The second significant advantage of the catalyst of the present invention is that the Ru / Ce 0.3 Zr 0.7 O2-F catalyst can significantly improve the activity of the catalyst. At the same time, the preparation method is simple and easy, and it is easy to realize industrialization.

[0026] The catalyst of the present invention can completely oxidize methane into carbon dioxide and water at a relatively low reaction temperature, thereby achieving standard emission of methane waste gas without generating more polluting by-products and avoiding secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the effect of hydrofluoric acid (HF) etching on the catalytic activity of the catalyst.

[0028] Figure 2 The effect of different acid (hydrofluoric acid, hydrochloric acid, nitric acid) etching on the catalytic activity of the catalyst. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with specific embodiments, but the scope of protection of the present invention is by no means limited. Unless otherwise specified, percentages in the specification are percentages by weight.

[0030] Example 1

[0031] 1%Ru / Ce 0.3 Zr 0.7 Preparation of O2-F catalyst: Ce(NO3)3·6H2O and ZrO(NO3)2 with a total weight of 4.24 g and a molar ratio of cerium to zirconium of 3:7 were dissolved in 60 mL of deionized water, 0.23 g of hydrogen peroxide (30 wt.%) was added dropwise, and stirred for 30 minutes, and ammonia (28 wt.%) was continued to be added dropwise until the pH value was about 8-9, and stirred for 2 hours, filtered, washed to neutral, dried in an oven at 120°C for 12 hours, and calcined in a muffle furnace at 500°C for 4 hours to obtain Ce 0.3 Zr 0.7 O2 carrier. 1g of the above Ce 0.3 Zr 0.7 The O2 carrier was dispersed in 2 mL of 10 wt.% HF solution, ultrasonically stirred for 10 minutes, filtered, washed until neutral, dried in an oven at 120°C for 12 hours, and calcined in a muffle furnace at 500°C for 4 hours to obtain Ce. 0.3 Zr0.7 O2-F carrier. Then 1g of the above Ce 0.3 Zr 0.7 Add 30 mL of deionized water to the O2-F carrier, drop 1.33 g of RuCl3 aqueous solution (Ru content is 0.754 wt.%), stir for 1 hour, filter, wash until neutral, dry in an oven at 120°C for 12 hours, and calcine in a muffle furnace at 500°C for 4 hours to obtain 1% Ru / Ce 0.3 Zr 0.7 O2-F catalyst.

[0032] Comparative Example 1

[0033] 1%Ru / Ce 0.3 Zr 0.7 Preparation of O2 catalyst: Ce(NO3)3·6H2O and ZrO(NO3)2 with a total weight of 4.24 g and a molar ratio of cerium to zirconium of 3:7 were dissolved in 60 mL of deionized water, 0.23 g of hydrogen peroxide (30 wt.%) was added dropwise, and stirred for 30 minutes, and ammonia (28 wt.%) was continued to be added dropwise until the pH value was about 8-9, and stirred for 2 hours, filtered, washed to neutral, dried in an oven at 120°C for 12 hours, and calcined in a muffle furnace at 500°C for 4 hours to obtain Ce 0.3 Zr 0.7 O2 carrier. Then 1g of the above Ce 0.3 Zr 0.7 Add 30 mL of deionized water to the O2 carrier, drop 1.33 g of RuCl3 aqueous solution (Ru content is 0.754 wt.%), stir for 1 hour, filter, wash until neutral, dry in an oven at 120°C for 12 hours, and calcine in a muffle furnace at 500°C for 4 hours to obtain 1% Ru / Ce 0.3 Zr 0.7 O2 catalyst.

[0034] Comparative Example 2

[0035] 1%Ru / Ce 0.3 Zr 0.7 Preparation of O2-N catalyst: The total weight of Ce(NO3)3·6H2O and ZrO(NO3)2 was 4.24 g, and the molar ratio of cerium to zirconium was 3:7, and 0.23 g of hydrogen peroxide (30 wt.%) was added dropwise, and stirred for 30 minutes. Ammonia (28 wt.%) was continued to be added dropwise until the pH value was about 8-9, and then stirred for 2 hours, filtered, washed to neutral, dried in an oven at 120°C for 12 hours, and calcined in a muffle furnace at 500°C for 4 hours to obtain Ce 0.3 Zr 0.7 O2 carrier. 1g of the above Ce 0.3 Zr 0.7The O2 carrier was dispersed in 2 mL of 10 wt.% HNO3 solution, ultrasonically stirred for 10 minutes, filtered, washed until neutral, dried in an oven at 120°C for 12 hours, and calcined in a muffle furnace at 500°C for 4 hours to obtain Ce. 0.3 Zr 0.7 O2-N carrier. Then 1g of the above Ce 0.3 Zr 0.7 Add 30 mL of deionized water to the O2-N carrier, drop 1.33 g of RuCl3 aqueous solution (Ru content is 0.754 wt.%), stir for 1 hour, filter, wash until neutral, dry in an oven at 120°C for 12 hours, and calcine in a muffle furnace at 500°C for 4 hours to obtain 1% Ru / Ce 0.3 Zr 0.7 O2-N catalyst.

[0036] Comparative Example 3

[0037] 1%Ru / Ce 0.3 Zr 0.7 Preparation of O2-Cl catalyst: The total weight of Ce(NO3)3·6H2O and ZrO(NO3)2 was 4.24 g, and the molar ratio of cerium to zirconium was 3:7. After adding 0.23 g of hydrogen peroxide (30 wt.%), the mixture was stirred for 30 minutes. Ammonia (28 wt.%) was added until the pH value was about 8-9, and then stirred for 2 hours. The mixture was filtered, washed to neutrality, dried in an oven at 120°C for 12 hours, and calcined in a muffle furnace at 500°C for 4 hours to obtain Ce. 0.3 Zr 0.7 O2 carrier. 1g of the above Ce 0.3 Zr 0.7 The O2 carrier was dispersed in 2 mL of 10 wt.% HCl solution, ultrasonically stirred for 10 minutes, filtered, washed until neutral, dried in an oven at 120°C for 12 hours, and calcined in a muffle furnace at 500°C for 4 hours to obtain Ce. 0.3 Zr 0.7 O2-Cl carrier. Then 1g of the above Ce 0.3 Zr 0.7 Add 30 mL of deionized water to the O2-Cl carrier, add 1.33 g of RuCl3 aqueous solution (Ru content is 0.754 wt.%) dropwise, stir for 1 hour, filter, wash until neutral, dry in an oven at 120°C for 12 hours, and calcine in a muffle furnace at 500°C for 4 hours to obtain 1% Ru / Ce 0.3 Zr 0.7 O2-Cl catalyst.

[0038] Experiment 1

[0039] The catalytic performance evaluation conditions are as follows: 0.1 g of catalyst was placed in a quartz tube fixed bed reactor, air was used as the oxidant, the methane concentration was 10000 ppm and the reaction space velocity was 30000 mL·g -1 ·h -1 The methane catalytic combustion reaction is carried out under the conditions of , and the reaction tail gas is detected by a gas chromatograph equipped with a filling column and a methane reformer.

[0040] Effect of HF acid etching on the catalytic activity of the catalyst Figure 1 As shown. Figure 1 It can be seen that the catalyst without acid etching can only achieve a methane conversion rate of >80% at above 550°C. The 1% Ru / Ce 0.3 Zr 0.7 O2-F catalyst can achieve a methane conversion rate of >80% at 500°C. For the methane catalytic combustion reaction, HF acid etching significantly broadens the temperature window of methane catalytic combustion, moves the reaction temperature window toward low temperature, and improves the methane catalytic activity of the obtained catalyst.

[0041] Effects of different acid (hydrofluoric acid, hydrochloric acid, nitric acid) etching on the catalytic activity of the catalyst Figure 2 As shown. Figure 2 It can be seen that under the acid etching conditions of three different acids, the catalyst prepared by HF acid etching exhibits the best methane catalytic combustion activity.

Claims

1. A Ru / Ce catalyst for methane catalytic combustion 0.3 Zr 0.7 O2-F catalyst, characterized in that The composition and weight percentage content of the catalyst are: Ru 1.0%, <h2 style=";text-align:left;direction:ltr">Ce<h2 style=";text-align:left;direction:ltr"> 0.3 <h2 style=";text-align:left;direction:ltr"> Zr<h2 style=";text-align:left;direction:ltr"> 0.7 <h2 style=";text-align:left;direction:ltr"> O2-F 99.0%.

2. The Ru / Ce catalyst for methane catalytic combustion reaction according to claim 1 0.3 Zr 0.7 The preparation method of O2-F catalyst is characterized in that: The method is prepared by oxidation coprecipitation-acid etching-immersion method, comprising the following steps: (1) Dissolve cerium nitrate and zirconium oxynitrate in deionized water at a molar ratio of cerium to zirconium of 3:7, then dropwise add hydrogen peroxide to 3+ Oxidation to Ce 4+ ; Then add ammonia water to adjust the pH to 8-9, so that Ce 4+ With Zr 4+ Complete co-precipitation; the obtained precipitate is washed to neutrality, then dried and calcined to obtain Ce 0.3 Zr 0.7 O2 carrier; (2) Ce 0.3 Zr 0.7 The O2 carrier is dispersed in HF solution, acid-etched, washed to neutrality, dried, and calcined to obtain Ce. 0.3 Zr 0.7 O2-F carrier; (3) Ce 0.3 Zr 0.7 The O2-F carrier was dispersed in deionized water, and a ruthenium chloride aqueous solution was added dropwise under stirring to load ruthenium chloride on Ce. 0.3 Zr 0.7 O2-F carrier, then washed to neutral, dried and calcined to obtain Ru / Ce 0.3 Zr 0.7 O2-F catalyst; wherein the amount of ruthenium trichloride aqueous solution added should be controlled so that the Ru loading in the catalyst after calcination is 1wt.%.

3. The method according to claim 2, characterized in that In step (1), stirring is continued for 2 hours after the ammonia water is added dropwise to ensure that the coprecipitation reaction is complete.

4. The method according to claim 2, characterized in that: The calcination temperature in step (1) is 400-600°C.

5. The method according to claim 2, characterized in that: In step (2), Ce 0.3 Zr 0.7 The O2 carrier is dispersed in the HF solution and ultrasonically stirred to enhance the acid etching effect.

6. The method according to claim 2, characterized in that The calcination temperature in step (2) is 400-600°C.

7. The method according to claim 2, characterized in that In step (3), after adding the ruthenium trichloride aqueous solution dropwise under stirring, stirring is continued for a period of time.

8. The method according to claim 2, characterized in that: The calcination temperature in step (3) is 400-600°C.

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