Compound desulfurizing agent suitable for desulfurizing under oxygen-containing condition as well as preparation method and application of compound desulfurizing agent

Abstract

The invention discloses a composite desulfurizing agent suitable for desulfurizing under an oxygen-containing condition as well as a preparation method and application of the composite desulfurizing agent, and belongs to the technical field of desulfurizing agents. The composite desulfurizer is of a double-layer composite structure. Wherein the outer layer is an iron oxyhydroxide layer and comprises iron oxyhydroxide and a first binder; and the inner layer is a copper-zinc-aluminum layer and comprises copper oxide, zinc oxide, aluminum oxide and a second binder. The service life of the obtained composite desulfurizer is remarkably prolonged under the oxygen-containing condition, the sulfur capacity of the desulfurizer can reach 10-20%, organic sulfur and inorganic sulfur can be removed at the same time in one step, the desulfurization cost is effectively reduced, and the composite desulfurizer has important application prospects. In addition, the preparation of the double-layer structure composite desulfurizer is realized through a double-layer banded extruder, the process is simple, and industrial batch production is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of desulfurizers, and particularly relates to a composite desulfurizer suitable for desulfurization under oxygen-containing conditions, a preparation method thereof, and applications thereof. Background Art

[0002] In chemical production, gases often contain hydrogen sulfide and organic sulfur. Organic sulfur generally refers to carbonyl sulfide and carbon disulfide. These sulfur-containing compounds are toxic to catalysts or affect product quality, such as causing yellowing of the product color. Organic sulfur is also more difficult to remove than hydrogen sulfide. Furthermore, during the gas production process, oxygen, as a gasifying agent, may remain in the atmosphere. For example, coke oven gas contains approximately 0.3-0.8% oxygen, and semi-coke gas contains approximately 0.5% oxygen.

[0003] Existing technologies typically employ a method that first removes hydrogen sulfide, then hydrolyzes organic sulfur to hydrogen sulfide, and finally removes hydrogen sulfide. For example, patent CN92105197.2 employs an alumina-supported alkali metal organic sulfur hydrolysis catalyst to hydrolyze COS into hydrogen sulfide, which is then removed. However, under aerobic conditions, hydrogen sulfide is first oxidized to active sulfur on the hydrolysis catalyst surface, which is then oxidized to sulfurous acid, which is further oxidized to sulfuric acid. This causes the organic sulfur hydrolysis catalyst to undergo sulfation, losing its alkaline active centers and thus poisoning and deactivating it, resulting in poor desulfurization and a lengthy process. Other methods employ high-temperature hydrogenation, such as patent CN202310970924.3, to first convert organic sulfur into hydrogen sulfide, followed by removal using zinc oxide. However, high-temperature hydrogenation consumes high energy, and the oxygen in the gas consumes valuable hydrogen and can easily cause the catalyst bed to overheat. Copper-nickel desulfurizers are also used to remove hydrogen sulfide and organic sulfur simultaneously, but the simultaneous removal of hydrogen sulfide and organic sulfur is poor, resulting in low sulfur capacity and high costs. Therefore, it is necessary to develop a desulfurizer with good desulfurization effect and suitable for desulfurization under oxygen-containing conditions. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite desulfurizer suitable for desulfurization under oxygen-containing conditions, as well as its preparation method and application. The composite desulfurizer significantly improves the desulfurizer life under oxygen-containing conditions, has a high sulfur capacity, and can simultaneously remove organic sulfur and inorganic sulfur in one step, effectively reducing the desulfurization cost, and has important application prospects.

[0005] To achieve the above object, the present invention adopts the following technical solutions: Provided is a composite desulfurizer suitable for desulfurization under oxygen-containing conditions, which has a double-layer composite structure; wherein: the outer layer is an iron oxyhydroxide layer, including iron oxyhydroxide and a first binder; the inner layer is a copper-zinc-aluminum layer, including copper oxide, zinc oxide, aluminum oxide and a second binder.

[0006] According to the above solution, in the inner layer, the mass ratio of copper oxide, zinc oxide and aluminum oxide is 5~10:20~50:30~70.

[0007] According to the above solution, in the outer layer, the mass ratio of iron oxyhydroxide to the first binder is 5-9:1.

[0008] According to the above solution, in the inner layer, the mass ratio of the total mass of copper oxide, zinc oxide and aluminum oxide to the second binder is 4-8:1.

[0009] According to the above solution, the first binder and the second binder are independently selected from at least one of bentonite, clay, and carboxymethyl cellulose (CMC).

[0010] According to the above solution, the mass ratio of the iron oxyhydroxide in the outer layer to the total mass of the copper oxide, zinc oxide and aluminum oxide in the inner layer is 1:1-3.

[0011] A method for preparing the composite desulfurizer suitable for desulfurization under oxygen-containing conditions is provided, comprising the following steps: 1) crushing and sieving the iron oxyhydroxide raw material to obtain an iron oxyhydroxide fine powder, then mixing it with a first binder, adding water, mixing, and kneading to obtain an iron oxyhydroxide wet bar; 2) Copper oxide, zinc oxide, and aluminum oxide powders are sieved separately and mixed to obtain a mixture, which is then mixed with a second binder, and water is added for mixing and kneading to obtain copper-zinc-aluminum wet bars; 3) The kneaded iron oxyhydroxide wet bars obtained in step 1) and the copper-zinc-aluminum wet bars obtained in step 2) are placed in a double-layer extruder to obtain wet bars having an iron oxyhydroxide layer as an outer layer and a copper-zinc-aluminum layer as an inner layer. The wet bars are then air-dried and then oven-dried to obtain a composite desulfurizer suitable for desulfurization under oxygen-containing conditions.

[0012] According to the above scheme, in step 1) and step 2), the sieving is performed through a 600-mesh sieve.

[0013] According to the above scheme, in step 1), the mass ratio of the fine iron oxyhydroxide powder to the first binder is 5-9:1.

[0014] According to the above scheme, in step 1), the mass ratio of the fine powder of ferric oxyhydroxide to water is 1:0.5-1.5.

[0015] According to the above scheme, in step 2), the mass ratio of the mixture to the second binder is 4-8:1.

[0016] According to the above scheme, in step 2), the mass ratio of the mixture to water is 1:0.5~1.0.

[0017] According to the above scheme, in step 2), the mass ratio of copper oxide, zinc oxide and aluminum oxide is 5-10:20-50:30-70.

[0018] According to the above scheme, in step 3), the mass ratio of the iron oxyhydroxide in the iron oxyhydroxide wet strip to the total mass of copper oxide, zinc oxide and aluminum oxide in the copper-zinc-aluminum wet strip is 1:1-3.

[0019] Provided is a use of the composite desulfurizer suitable for desulfurization under oxygen-containing conditions in the desulfurization of sulfur-containing gas, wherein the sulfur-containing gas includes organic sulfur, inorganic sulfur and oxygen.

[0020] According to the above scheme, the organic sulfur content is 1~100ppm; the inorganic sulfur content is 100~2000ppm; and the oxygen content is 0.05~1.2%.

[0021] According to the above scheme, the sulfur capacity of the composite desulfurizer is 10-20%.

[0022] According to the above scheme, the desulfurization rate of the composite desulfurizer is greater than 99%, and the total sulfur at the outlet is less than 0.1 ppm.

[0023] According to the above scheme, the process conditions for desulfurization by the composite desulfurizer are: space velocity 250~1500h -1 , temperature 60~200℃.

[0024] The present invention provides a composite desulfurizer suitable for desulfurization under oxygen-containing conditions. The composite desulfurizer has a double-layer composite structure, wherein the inner layer comprises copper oxide, zinc oxide, and aluminum oxide, and the outer layer is a hydroxyl iron layer. When desulfurization is carried out under oxygen conditions, the hydroxyl iron outer layer preferentially contacts the sulfur-containing gas and reacts with hydrogen sulfide in the sulfur-containing gas to remove the hydrogen sulfide first, thereby avoiding competition between hydrogen sulfide and organic sulfur on the expensive copper-zinc active component of the inner layer, improving the efficiency of the copper-zinc component in removing organic sulfur, and reducing the desulfurization cost. The hydroxyl iron outer layer reacts with hydrogen sulfide and can also undergo a regeneration reaction with oxygen. On the one hand, the hydroxyl iron outer layer can be continuously regenerated, thereby increasing the speed of removing hydrogen sulfide and increasing the sulfur capacity. On the other hand, the oxygen content in the raw material is reduced, thereby protecting the copper-zinc-aluminum inner layer, avoiding catalyst poisoning and deactivation, and extending the service life of the desulfurizer.

[0025] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a composite desulfurizer suitable for desulfurization under oxygen-containing conditions. The composite desulfurizer has a double-layer composite structure, an inner layer comprising copper oxide, zinc oxide, and aluminum oxide, and an outer layer comprising an iron oxyhydroxide layer. The inexpensive iron oxyhydroxide in the outer layer reacts preferentially with hydrogen sulfide and is regenerated using oxygen, thereby improving the catalytic efficiency and sulfur capacity of the iron oxyhydroxide. Furthermore, the reaction of the expensive copper and zinc in the inner layer with hydrogen sulfide is avoided, thereby promoting the efficiency of the copper and zinc components in removing organic sulfur. Furthermore, the composite desulfurizer can reduce oxygen concentration, avoid catalyst poisoning and deactivation in the presence of oxygen, and protect the copper, zinc, and aluminum inner layers. The composite desulfurizer significantly improves the service life of the desulfurizer under oxygen-containing conditions, achieves a sulfur capacity of up to 10-20%, and can simultaneously remove organic and inorganic sulfur in one step, effectively reducing desulfurization costs. The composite desulfurizer has important application prospects.

[0026] 2. The present invention realizes the preparation of a double-layer structure composite desulfurizer for the first time through a double-layer extruder, which has a simple process and is conducive to industrial batch production. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] Example 1 A method for preparing a composite desulfurizer suitable for desulfurization under oxygen-containing conditions is provided, comprising the following steps: 1) Grind and sieve ferric oxyhydroxide to obtain a 600-mesh fine powder. Then, add 56g of bentonite and 2g of CMC as binders to 500g of ferric oxyhydroxide fine powder, mix well, and add 400g of water. After mixing evenly, knead it into long strips for later use.

[0029] 2) Take 200g, 600g, and 600g of 600-mesh copper oxide, zinc oxide, and aluminum oxide, respectively, and mix them well. Then add 180g of bentonite and 5g of CMC to the mixture, mix well, and then add 1300g of water. After mixing evenly, knead it into long strips for later use.

[0030] 3) The iron oxyhydroxide wet bars kneaded in step 1) and the copper, zinc, and aluminum wet bars kneaded in step 2) are placed in a double-layer extruder to extrude wet bars having a diameter of 5 mm and an iron oxyhydroxide outer layer and an inner layer of copper, zinc, and aluminum. The wet bars are air-dried and then oven-dried at 120° C. for 5 h to obtain a composite desulfurizer suitable for desulfurization under oxygen-containing conditions.

[0031] Example 2 A method for preparing a composite desulfurizer suitable for desulfurization under oxygen-containing conditions is provided, comprising the following steps: 1) Grind and sieve ferric oxyhydroxide to obtain a 600-mesh fine powder. Then, add 128g of clay and 2g of CMC as a binder to 700g of ferric oxyhydroxide fine powder, mix well, and add 600g of water. After mixing evenly, knead it into long strips for later use.

[0032] 2) Take 120g, 500g and 1200g of 600-mesh copper oxide, zinc oxide and aluminum oxide respectively, mix well, then add 400g of bentonite and 4g of CMC to the mixture, mix well, add 1600g of water, mix well, and knead into long strips for later use.

[0033] 3) The iron oxyhydroxide wet bars kneaded in step 1) and the copper, zinc, and aluminum wet bars kneaded in step 2) are placed in a double-layer extruder to obtain wet bars with a diameter of 4 mm, the wet bars having the iron oxyhydroxide as an outer layer and the copper, zinc, and aluminum as an inner layer. The wet bars are air-dried and then oven-dried at 140° C. for 2 h to obtain a composite desulfurizer suitable for desulfurization under oxygen-containing conditions.

[0034] Example 3 A method for preparing a composite desulfurizer suitable for desulfurization under oxygen-containing conditions is provided, comprising the following steps: 1) Grind and sieve ferric oxyhydroxide to obtain a 600-mesh fine powder. Then, add 30g of bentonite, 40g of clay, and 1g of CMC to 550g of ferric oxyhydroxide fine powder. Mix well and add 400g of water. After mixing evenly, knead into long strips for later use.

[0035] 2) Take 90g, 300g and 900g of 600-mesh copper oxide, zinc oxide and aluminum oxide respectively, mix well, then add 300g of bentonite and 3g of CMC to the mixture, mix well, add 1100g of water, mix well, and knead into long strips for later use.

[0036] 3) The iron oxyhydroxide wet bars kneaded in step 1) and the copper, zinc, and aluminum wet bars kneaded in step 2) are placed in a double-layer extruder to obtain wet bars with a diameter of 4 mm, the wet bars having the iron oxyhydroxide as an outer layer and the copper, zinc, and aluminum as an inner layer. The wet bars are air-dried and then oven-dried at 130° C. for 3 hours to obtain a composite desulfurizer suitable for desulfurization under oxygen-containing conditions.

[0037] The desulfurizers prepared in Examples 1-3 were cut into 4-5 mm long strips, and 30 ml of each strip was used to compare desulfurization performance under aerobic conditions with a commercially available copper-nickel desulfurizer (5% nickel oxide, 25% copper oxide, and 70% aluminum oxide, expressed as percentages by mass). Two different gas sources (Source 1 and Source 2) were used for these experiments. The results are shown in Tables 1 and 2. When the total sulfur at the outlet reached ≥ 0.1 ppm, indicating catalyst bed breakthrough, the test was terminated and the desulfurizer sulfur capacity was calculated. The desulfurizer sulfur capacity represents the mass of sulfide removed (absorbed) per unit mass of the desulfurizer, converted to elemental sulfur, and expressed as g (sulfur) / g (desulfurizer). It can also be expressed as a percentage.

[0038] Table 1. Performance comparison of the desulfurizers obtained in Examples 1-3 and commercially available copper-nickel desulfurizers for gas source 1

[0039] In Table 1, the gas source and process conditions are as follows: Gas source 1: H2S 0.1% + COS 0.01% + CH3SH 0.001% + O21%, residual nitrogen.

[0040] Process conditions: air velocity 500h -1 , reaction temperature 150℃, normal pressure.

[0041] Table 2. Performance comparison of the desulfurizers obtained in Examples 1-3 and commercially available copper-nickel desulfurizers for gas source 2

[0042] In Table 2, the gas source and process conditions are as follows: Gas source 2: H2S 0.12% + COS 0.005% + CS2 0.005% + O2 0.15%, residual nitrogen.

[0043] Process conditions: air velocity 1000h -1 , reaction temperature 120℃, normal pressure.

[0044] The data in Tables 1-2 show that the desulfurizers obtained in the examples of the present invention can achieve high sulfur capacity under aerobic conditions, reaching as high as 13.4-20.2% (i.e., 100g of desulfurizer can remove 13.4-20.2g of sulfur), far exceeding commercially available copper-nickel desulfurizers. When the oxygen content is low, at 0.15%, the commercial copper-nickel desulfurizer has a sulfur capacity of 8.7%, approximately 44% of the sulfur capacity of the desulfurizer obtained in Example 1. When the oxygen content is high, at 1%, the commercial copper-nickel desulfurizer has a sulfur capacity of only 4.6%, while the sulfur capacity of the examples of the present invention can reach as high as 20.2%, approximately 4.5 times that of commercial copper-nickel desulfurizers. This indicates that under aerobic conditions, oxygen content significantly affects the desulfurization performance of the desulfurizer. The composite desulfurizer of the present invention can simultaneously remove both organic and inorganic sulfur when used in desulfurization conditions, demonstrating excellent desulfurization performance.

[0045] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A composite desulfurizer suitable for desulfurization under oxygen-containing conditions, characterized in that: The composite desulfurizer is a double-layer composite structure, wherein: the outer layer is an iron oxide layer, including iron oxyhydroxide and a first binder; the inner layer is a copper-zinc-aluminum layer, including copper oxide, zinc oxide, aluminum oxide and a second binder.

2. The composite desulfurizer according to claim 1, characterized in that In the inner layer, the mass ratio of copper oxide, zinc oxide and aluminum oxide is 5-10:20-50:30-70.

3. The composite desulfurizer according to claim 1, characterized in that In the outer layer, the mass ratio of ferric oxyhydroxide to the first binder is 5-9:1; in the inner layer, the mass ratio of the total mass of copper oxide, zinc oxide and aluminum oxide to the second binder is 4-8:

1.

4. The composite desulfurizer according to claim 1, characterized in that The first binder and the second binder are independently selected from at least one of bentonite, clay, and CMC.

5. The composite desulfurizer according to claim 1, characterized in that The mass ratio of the iron oxyhydroxide in the outer layer to the total mass of the copper oxide, zinc oxide and aluminum oxide in the inner layer is 1:1-3.

6. A method for preparing a composite desulfurizer suitable for desulfurization under oxygen-containing conditions according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) crushing and sieving the iron oxyhydroxide raw material to obtain an iron oxyhydroxide fine powder, then mixing it with a first binder, adding water, mixing, and kneading to obtain an iron oxyhydroxide wet bar; 2) Copper oxide, zinc oxide, and aluminum oxide powders are sieved separately and mixed to obtain a mixture, which is then mixed with a second binder, and water is added for mixing and kneading to obtain copper-zinc-aluminum wet bars; 3) The kneaded iron oxyhydroxide wet bars obtained in step 1) and the copper-zinc-aluminum wet bars obtained in step 2) are placed in a double-layer extruder to obtain wet bars having an iron oxyhydroxide layer as an outer layer and a copper-zinc-aluminum layer as an inner layer. The wet bars are then air-dried and then oven-dried to obtain a composite desulfurizer suitable for desulfurization under oxygen-containing conditions.

7. The preparation method according to claim 6, characterized in that In the step 1), the mass ratio of the ferric oxyhydroxide powder to the first binder is 5-9:1; and in the step 2), the mass ratio of the mixture to the second binder is 4-8:

1.

8. The preparation method according to claim 6, characterized in that In the step 1), the mass ratio of the iron oxyhydroxide powder to water is 1:0.5-1.5; in the step 2), the mass ratio of the mixture to water is 1:0.5-1.

0.

9. The preparation method according to claim 6, characterized in that In the step 3), the mass ratio of the iron oxyhydroxide in the iron oxyhydroxide wet strip to the total mass of the copper oxide, zinc oxide and aluminum oxide in the copper-zinc-aluminum wet strip is 1:1-3.

10. Use of the composite desulfurizer suitable for desulfurization under oxygen-containing conditions according to any one of claims 1 to 5 in desulfurization of sulfur-containing gas, characterized in that: The sulfur-containing gas includes organic sulfur, inorganic sulfur and oxygen.

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