A method for photocatalytic removal of hydrogen sulfide from coke oven gas

Abstract

The present invention belongs to the technical field of coke oven gas purification and treatment, and specifically discloses a method for photocatalytically removing hydrogen sulfide from coke oven gas. The method adopts the synthetic concept of synergistic effect of silver doping and polyethyleneimine to promote the generation of oxygen vacancies. On the one hand, polyethyleneimine provides alkaline conditions, and on the other hand, the lone electron pair on nitrogen coordinates with zinc, and the synergistic effect with silver promotes the generation of abundant oxygen vacancies. Furthermore, polyethyleneimine acts as a surfactant to prevent the agglomeration of generated ZnO, thereby increasing the reaction sites. Subsequently, the abundant oxygen vacancies promote the formation of ZnO. 1‑x The catalyst reacts with H2S in series, generating an in-situ 1D / 3D-ZnS / ZnO heterojunction to further reduce the recombination of photogenerated electrons and holes. The catalyst then converts H2S into elemental sulfur through the photogenerated electrons and holes. The catalyst is then cleaned with a carbon disulfide solution to regenerate the catalyst. This method not only improves H2S removal efficiency but also reduces operating costs and environmental pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of coke oven gas purification and treatment, and in particular relates to a method for photocatalytically removing hydrogen sulfide from coke oven gas. Background Art

[0002] Coke oven gas, a byproduct of industrial production, contains a variety of harmful gases, among which hydrogen sulfide (H2S) is a pollutant that is extremely harmful to the environment and human health. Traditional H2S removal methods include wet desulfurization and dry desulfurization. While dry desulfurization offers high desulfurization accuracy, it requires frequent desulfurizer replacement and is costly. Furthermore, traditional dry desulfurization adsorbents consume significant energy during regeneration, resulting in incomplete regeneration and damage to the adsorbent structure, making secondary use difficult. While wet desulfurization allows for continuous operation, it also presents challenges such as complex process flows, high equipment investment, high operating costs, and the generation of secondary pollution.

[0003] Existing desulfurization methods have problems such as complex operation, high cost, and easy secondary pollution. Therefore, developing an efficient, low-cost, and environmentally friendly method for removing H2S from coke oven gas has important research value and application prospects. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention proposes a method for photocatalytic removal of hydrogen sulfide in coke oven gas. The method of the present invention adopts the synergistic effect of silver doping and polyethyleneimine to introduce abundant oxygen vacancies into the ZnO catalyst, and utilizes the oxygen vacancy-rich ZnO 1-x Catalyst: At the beginning of the reaction, sulfur enters the vacancies of ZnO, forming a 1D / 3D-ZnS / ZnO heterojunction in situ. Photocatalytic technology is used to remove H2S from coke oven gas, and photogenerated electrons and holes are used to convert H2S into elemental sulfur, avoiding the complex chemical reactions and the use of large amounts of chemicals in traditional desulfurization methods. It has the advantages of simple process flow, low cost, and environmental protection.

[0005] The technical solution protected by the present invention is: a method for photocatalytically removing hydrogen sulfide from coke oven gas, which is specifically carried out according to the following steps:

[0006] Step S1: ZnO 1-x Catalyst preparation: Dissolve 0.1-0.5g AgCl in 50-70mL deionized water, then add 3-5g ZnNO3. After stirring to dissolve, add 2-5g polyethyleneimine and sonicate for 0.5-1h. Then, add the mixed solution to a 100mL polytetrafluoroethylene autoclave, react at 120℃ for 8-12h, filter, and then calcine in an oven at 200-300℃ for 2-3h.

[0007] Step S2, build a photocatalytic reaction device: prepare the ZnO1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under light conditions, the abundant oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S generates a 1D / 3D-ZnS / ZnO heterojunction in situ;

[0008] Step S3, catalyst regeneration: the 1D / 3D-ZnS / ZnO heterojunction catalyst with reduced activity is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

[0009] Furthermore, the flow rate of the coke oven gas in step S2 is 50-200 mL / min.

[0010] Furthermore, in step S2, the illumination is carried out using an ultraviolet-visible light source with a wavelength range of 300-800 nm and an illumination intensity of 50-200 mW / cm 2 .

[0011] Furthermore, a method for photocatalytically removing hydrogen sulfide from coke oven gas, step S1, ZnO 1-x Catalyst preparation: 0.2 g of AgCl was dissolved in 55 mL of deionized water, followed by the addition of 3.5 g of ZnNO3. After stirring and dissolving, 3 g of polyethyleneimine was added and ultrasonicated for 0.6 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 9 h. The mixture was filtered and then calcined in an oven at 230 °C for 2.2 h.

[0012] Step S2, build a photocatalytic reaction device: prepare the ZnO 1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under light conditions, the abundant oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S generates a 1D / 3D-ZnS / ZnO heterojunction in situ;

[0013] Step S3, catalyst regeneration: the 1D / 3D-ZnS / ZnO heterojunction catalyst with reduced activity is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

[0014] Furthermore, a method for photocatalytically removing hydrogen sulfide from coke oven gas is specifically carried out according to the following steps:

[0015] Step S1: ZnO 1-xCatalyst preparation: 0.3 g of AgCl was dissolved in 60 mL of deionized water, followed by the addition of 4 g of ZnNO3. After stirring and dissolving, 4 g of polyethyleneimine was added and ultrasonicated for 0.7 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 10 h. The mixture was filtered and then calcined in an oven at 250 °C for 2-3 h.

[0016] Step S2, build a photocatalytic reaction device: prepare the ZnO 1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under light conditions, the abundant oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S generates a 1D / 3D-ZnS / ZnO heterojunction in situ;

[0017] Step S3, catalyst regeneration: the 1D / 3D-ZnS / ZnO heterojunction catalyst with reduced activity is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

[0018] Furthermore, a method for photocatalytically removing hydrogen sulfide from coke oven gas is specifically carried out according to the following steps:

[0019] Step S1: ZnO 1-x Catalyst preparation: 0.4 g of AgCl was dissolved in 65 mL of deionized water, followed by the addition of 4.5 g of ZnNO3. After stirring and dissolving, 4.5 g of polyethyleneimine was added and ultrasonicated for 0.9 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 11 h. The mixture was filtered and then calcined in an oven at 280 °C for 2-3 h.

[0020] Step S2, build a photocatalytic reaction device: prepare the ZnO 1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under light conditions, the abundant oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S generates a 1D / 3D-ZnS / ZnO heterojunction in situ;

[0021] Step S3, catalyst regeneration: the 1D / 3D-ZnS / ZnO heterojunction catalyst with reduced activity is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. Environmental protection and energy saving: This method uses photocatalytic technology to remove H2S from coke oven gas, utilizing photogenerated electrons and holes to convert H2S into elemental sulfur. This avoids the complex chemical reactions and large amounts of chemicals used in traditional desulfurization methods, resulting in a simple process flow, low cost, and environmentally friendly advantages. This method does not require harsh conditions such as high temperature and high pressure, is easy to operate, consumes low energy, and does not generate secondary pollution.

[0024] 2. Efficiency improvement: The present invention uses the synergistic effect of silver doping and polyethyleneimine to introduce abundant oxygen vacancies into the ZnO catalyst. Furthermore, the abundant oxygen vacancies then promote the ZnO 1-x A tandem reaction with H2S creates an in-situ 1D / 3D ZnS / ZnO heterojunction, further reducing the recombination of photogenerated electrons and holes. This allows H2S to be converted to elemental sulfur via these photogenerated electrons and holes. The oxygen vacancies and the ZnS / ZnO heterojunction synergistically enhance the separation efficiency of photogenerated carriers, increasing H2S conversion by over 40% compared to conventional ZnO.

[0025] 3. Simple regeneration: Cleaning with carbon disulfide solution allows for rapid catalyst regeneration with good results, extending the catalyst's service life. This process is simple to operate and reduces operating costs. Traditional adsorbent regeneration typically requires an oxygen atmosphere at 500 degrees Celsius and high temperature and pressure, resulting in high energy consumption and incomplete adsorbent regeneration. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Figure 1 The figure is a reaction flow chart of the present invention.

[0028] Figure 2 It is a dynamic catalytic mechanism.

[0029] Figure 3 This is the electron paramagnetic resonance spectrum at room temperature.

[0030] Figure 4 The figure is a comparison of the desulfurization effects of different catalysts. DETAILED DESCRIPTION

[0031] In order to make the objects, features and advantages of the present invention clear and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0032] like Figure 1 As shown, a method for photocatalytically removing hydrogen sulfide from coke oven gas is specifically carried out according to the following steps:

[0033] Step S1: ZnO 1-xCatalyst preparation: 0.1-0.5g AgCl was dissolved in 50-70mL deionized water, followed by the addition of 3-5g ZnNO3. After stirring and dissolving, 2-5g polyethyleneimine was added and ultrasonicated for 0.5-1h. The mixed solution was then added to a 100mL polytetrafluoroethylene autoclave, reacted at 120℃ for 8-12h, filtered, and then calcined in an oven at 200-300℃ for 2-3h to obtain oxygen vacancy-rich ZnO. 1-x catalyst.

[0034] Step S2, build a photocatalytic reaction device: prepare the ZnO 1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under the conditions of light, ZnO 1-x V0 acts as an electron trap to promote the photogenerated electrons (e - ) and holes (h + ) separation, the abundant oxygen vacancies promote the ZnO 1-x Reacts in series with H2S.

[0035] like Figure 2 As shown, the process of the tandem reaction is as follows:

[0036] H2S preferentially adsorbs on V o site, and e - The reaction generates S 2- :

[0037] H2S+2e - →S 2- +H2

[0038] S 2- Occupy V o position, so that part of the ZnO surface is converted into ZnS in situ, forming a 1D / 3D ZnS / ZnO heterojunction, further reducing the e - -h + Compound rate.

[0039] Photogenerated electron reduction and hole oxidation:

[0040] H2S and e - , h + The reaction produces S8:

[0041] H2S+2e - →S 2- +H2

[0042] S 2- +2h + →S8

[0043] Step S3, catalyst regeneration: the ZnO 1-xThe catalyst is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

[0044] The method of the present invention adopts the synergistic effect of silver doping and polyethyleneimine. The addition of Ag disrupts the ZnO lattice and promotes the generation of oxygen vacancies. On the one hand, polyethyleneimine provides alkaline conditions. On the other hand, the lone electron pair on N coordinates with Zn, and the synergistic effect with Ag promotes the generation of abundant oxygen vacancies, thereby introducing abundant oxygen vacancies into the ZnO catalyst. Furthermore, polyethyleneimine acts as a surfactant to prevent the agglomeration of the generated ZnO and increase the reaction sites. Subsequently, during the photocatalytic reaction, the abundant oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S creates in situ 1D / 3D-ZnS / ZnO, further reducing the recombination of photogenerated electrons and holes. H2S is then converted to elemental sulfur via the photogenerated electrons and holes. The catalyst is then cleaned with a carbon disulfide solution to achieve catalyst regeneration. Traditional dry desulfurization uses ZnO as an adsorbent, which has limited sulfur capacity and difficult-to-control adsorbent regeneration. This method not only improves H2S removal efficiency, but also reduces operating costs and environmental pollution.

[0045] In order to introduce the preparation of the catalyst of the present invention and the catalytic principle in detail above, the method of the present invention will be described in detail through several specific examples below. Example 1

[0046] A method for photocatalytically removing hydrogen sulfide from coke oven gas is specifically carried out according to the following steps:

[0047] Step S1: ZnO 1-x Catalyst preparation: 0.2 g of AgCl was dissolved in 55 mL of deionized water, followed by the addition of 3.5 g of ZnNO3. After stirring and dissolving, 3 g of polyethyleneimine was added and ultrasonicated for 0.6 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 9 h. The mixture was filtered and then calcined in an oven at 230 °C for 2.2 h.

[0048] Step S2, build a photocatalytic reaction device: use a fixed bed photocatalytic reactor (quartz tube with an inner diameter of 10 mm) to prepare ZnO 1-x The catalyst was loaded into the photocatalytic reaction device at a loading amount of 0.2 g and a bed height of 2-5 cm. Coke oven gas was passed through the reaction device at a flow rate of 80 mL / min. The illumination was carried out using a UV-visible light source with a wavelength range of 300-800 nm and an intensity of 50-200 mW / cm 2 , illumination time: 200min, reaction temperature: 40℃, pressure: normal pressure, abundant oxygen vacancies promote ZnO 1-xA tandem reaction with H2S generates a 1D / 3D ZnS / ZnO heterojunction in situ;

[0049] Step S3: As the reaction proceeds, sulfur gradually accumulates on the catalyst surface, causing the catalyst activity to decrease. When the catalyst activity decreases to a certain level, the catalyst is cleaned with a carbon disulfide solution to dissolve the sulfur, thereby regenerating the catalyst. Example 2

[0050] A method for photocatalytically removing hydrogen sulfide from coke oven gas is specifically carried out according to the following steps:

[0051] Step S1: ZnO 1-x Catalyst preparation: 0.3 g of AgCl was dissolved in 60 mL of deionized water, followed by the addition of 4 g of ZnNO3. After stirring and dissolving, 4 g of polyethyleneimine was added and ultrasonicated for 0.7 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 10 h. The mixture was filtered and then calcined in an oven at 250 °C for 2-3 h.

[0052] Step S2, build a photocatalytic reaction device: use a fixed bed photocatalytic reactor (quartz tube with an inner diameter of 10 mm) to prepare ZnO 1-x The catalyst was loaded into the photocatalytic reaction device at a loading amount of 0.3 g and a bed height of 2-5 cm. Coke oven gas was passed through the reaction device at a flow rate of 150 mL / min. The illumination was carried out using a UV-visible light source with a wavelength range of 300-800 nm and an intensity of 50-200 mW / cm 2 , illumination time: 200min, reaction temperature: 50℃, pressure: normal pressure, abundant oxygen vacancies promote ZnO 1-x A tandem reaction with H2S generates a 1D / 3D ZnS / ZnO heterojunction in situ;

[0053] Step S3: As the reaction proceeds, sulfur gradually accumulates on the catalyst surface, causing the catalyst activity to decrease. When the catalyst activity decreases to a certain level, the catalyst is cleaned with a carbon disulfide solution to dissolve the sulfur, thereby regenerating the catalyst. Example 3

[0054] A method for photocatalytically removing hydrogen sulfide from coke oven gas is specifically carried out according to the following steps:

[0055] Step S1: ZnO 1-xCatalyst preparation: 0.4 g of AgCl was dissolved in 65 mL of deionized water, followed by the addition of 4.5 g of ZnNO3. After stirring and dissolving, 4.5 g of polyethyleneimine was added and ultrasonicated for 0.9 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 11 h. The mixture was filtered and then calcined in an oven at 280 °C for 2-3 h.

[0056] Step S2, build a photocatalytic reaction device: use a fixed bed photocatalytic reactor (quartz tube with an inner diameter of 10 mm) to prepare ZnO 1-x The catalyst was loaded into the photocatalytic reaction device at a loading amount of 0.4 g and a bed height of 2-5 cm. Coke oven gas was passed through the reaction device at a flow rate of 180 mL / min. The illumination was carried out using a UV-visible light source with a wavelength range of 300-800 nm and an intensity of 50-200 mW / cm 2 , illumination time: 200min, reaction temperature: 70℃, pressure: normal pressure, abundant oxygen vacancies promote ZnO 1-x A tandem reaction with H2S generates a 1D / 3D ZnS / ZnO heterojunction in situ;

[0057] Step S3: As the reaction proceeds, sulfur gradually accumulates on the catalyst surface, causing the catalyst activity to decrease. When the catalyst activity decreases to a certain level, the catalyst is cleaned with a carbon disulfide solution to dissolve the sulfur, thereby regenerating the catalyst.

[0058] In addition, the present invention provides a comparative example, which uses conventional zinc oxide prepared by doping with silver (Ag) alone and participates in the subsequent photocatalytic reaction. During the photocatalytic reaction, the H2S conversion rate is monitored by online gas chromatography (FPD detector).

[0059] like Figure 3 As shown in the figure, the oxygen vacancy concentration of zinc oxide prepared by silver (Ag) doping alone is lower than that of zinc oxide prepared by the synergistic action of silver (Ag) and polyethyleneimine (PEI), which directly indicates that the synergistic functionalization of silver and polyethyleneimine can significantly promote the formation of higher concentrations of oxygen vacancies during the synthesis process.

[0060] like Figure 4As shown, the ZnO prepared by the synergistic effect of Ag doping and PEI in the present invention has a short pre-reaction time (100 minutes) and a higher efficiency (99.5%). Experimental comparisons show that the photocatalytic removal of H2S from coke oven gas provided by the present invention achieves efficient, environmentally friendly, and low-cost H2S removal by using a mesoporous ZnO catalyst and photogenerated electrons and holes to convert H2S into elemental sulfur, combined with a carbon disulfide solution to clean and regenerate the catalyst. This method has significant application value in improving coke oven gas treatment efficiency and protecting the environment.

[0061] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for photocatalytically removing hydrogen sulfide from coke oven gas, characterized in that: Follow these steps: Step S1: ZnO 1-x Catalyst preparation: Dissolve 0.1-0.5g AgCl in 50-70mL deionized water, then add 3-5g ZnNO3. After stirring to dissolve, add 2-5g polyethyleneimine and sonicate for 0.5-1h. Then, add the mixed solution to a 100mL polytetrafluoroethylene autoclave, react at 120℃ for 8-12h, filter, and then calcine in an oven at 200-300℃ for 2-3h. Step S2, build a photocatalytic reaction device: prepare the ZnO 1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under light conditions, oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S generates a 1D / 3D-ZnS / ZnO heterojunction in situ; Step S3, catalyst regeneration: the 1D / 3D-ZnS / ZnO heterojunction catalyst with reduced activity is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

2. The method for photocatalytically removing hydrogen sulfide from coke oven gas according to claim 1, characterized in that: The flow rate of the coke oven gas in step S2 is 50-200 mL / min.

3. The method for photocatalytically removing hydrogen sulfide from coke oven gas according to claim 2, characterized in that: In step S2, the illumination is carried out using an ultraviolet-visible light source with a wavelength range of 300-800 nm and an illumination intensity of 50-200 mW / cm 2 .

4. The method for photocatalytically removing hydrogen sulfide from coke oven gas according to claim 1, characterized in that: Follow these steps: Step S1: ZnO 1-x Catalyst preparation: 0.2 g of AgCl was dissolved in 55 mL of deionized water, followed by the addition of 3.5 g of ZnNO3. After stirring and dissolving, 3 g of polyethyleneimine was added and ultrasonicated for 0.6 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 9 h. The mixture was filtered and then calcined in an oven at 230 °C for 2.2 h. Step S2, build a photocatalytic reaction device: prepare the ZnO 1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under light conditions, oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S generates a 1D / 3D-ZnS / ZnO heterojunction in situ; Step S3, catalyst regeneration: the 1D / 3D-ZnS / ZnO heterojunction catalyst with reduced activity is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

5. The method for photocatalytically removing hydrogen sulfide from coke oven gas according to claim 1, characterized in that: Follow these steps: Step S1: ZnO 1-x Catalyst preparation: 0.3 g of AgCl was dissolved in 60 mL of deionized water, followed by the addition of 4 g of ZnNO3. After stirring and dissolving, 4 g of polyethyleneimine was added and ultrasonicated for 0.7 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 10 h. The mixture was filtered and then calcined in an oven at 250 °C for 2-3 h. Step S2, build a photocatalytic reaction device: prepare the ZnO 1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under light conditions, oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S generates a 1D / 3D-ZnS / ZnO heterojunction in situ; Step S3, catalyst regeneration: the 1D / 3D-ZnS / ZnO heterojunction catalyst with reduced activity is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

6. The method for photocatalytically removing hydrogen sulfide from coke oven gas according to claim 1, characterized in that: Follow these steps: Step S1: ZnO 1-x Catalyst preparation: 0.4 g of AgCl was dissolved in 65 mL of deionized water, followed by the addition of 4.5 g of ZnNO3. After stirring and dissolving, 4.5 g of polyethyleneimine was added and ultrasonicated for 0.9 h. The mixed solution was then added to a 100 mL polytetrafluoroethylene autoclave and reacted at 120 °C for 11 h. The mixture was filtered and then calcined in an oven at 280 °C for 2-3 h. Step S2, build a photocatalytic reaction device: prepare the ZnO 1-x The catalyst is loaded into the photocatalytic reaction device, and the coke oven gas passes through the reaction device. Under light conditions, oxygen vacancies promote the ZnO 1-x A tandem reaction with H2S generates a 1D / 3D-ZnS / ZnO heterojunction in situ; Step S3, catalyst regeneration: the 1D / 3D-ZnS / ZnO heterojunction catalyst with reduced activity is cleaned with a carbon disulfide solution to achieve catalyst regeneration.

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