Modified activated carbon catalysts for room temperature catalytic oxidation of H2S, their preparation and application

Abstract

This invention relates to a modified activated carbon catalyst for the room-temperature catalytic oxidation of H2S, its preparation, and its application. The modified activated carbon catalyst consists of an activated carbon support and a co-catalyst, wherein the co-catalyst accounts for 2-20% of the modified activated carbon catalyst by mass. The preparation method of this invention is simple, using low-cost recycled activated carbon as raw material. A catalyst with a certain shape and mechanical strength is obtained through appropriate proportioning and molding techniques. The addition of the co-catalyst effectively enhances the sustained dissociation capacity of H2S. Biomass ultrafine particles are used as template agents for pore modification, forming a macroporous structure, which effectively reduces the diffusion resistance of gas molecules, making it easier for reactants to enter the columnar activated carbon for adsorption and activation, effectively improving the utilization rate of the carbon matrix, and increasing the sulfur capacity by approximately 24%. The catalyst achieves a maximum sulfur capacity of 1.23 g H2S / g catalyst, which can be used for the low-temperature and efficient removal of H2S in industrial applications.

Description

Technical Field

[0001] This invention relates to the field of desulfurization technology, and in particular to a modified activated carbon catalyst for room temperature catalytic oxidation of H2S, its preparation and application. Background Technology

[0002] Hydrogen sulfide (H2S) is a toxic acidic gas commonly found in the extraction and purification processes of fossil fuels such as coal, oil, and natural gas. In production processes, it not only corrodes equipment but also harms human health and pollutes the environment. Efficient H2S removal has become an indispensable part of related processes.

[0003] Compared to the more mature Claus process and metal oxide desulfurization methods, the catalytic oxidation of H2S to elemental sulfur at room temperature based on carbonaceous materials is an environmentally friendly and low-cost solution because it can simultaneously remove H2S and generate elemental sulfur, and can be applied to fine desulfurization. Various carbon materials, such as activated carbon, carbon nanotubes, and mesoporous carbon, are widely used as metal-free catalysts to promote the oxidation of H2S to elemental sulfur at low temperatures. Activated carbon, as an inexpensive carbon material, is commonly used in industry, but its desulfurization performance still needs further improvement. Numerous studies have shown that the adsorption and catalytic performance of carbon-based catalysts depends not only on the chemical properties of the carbon surface but also on the pore structure of the carbon. In industrial applications, the pressure drop must also be considered in terms of activated carbon forming. Commercialization of activated carbon desulfurizers requires specific shapes, i.e., as extrudates or in bulk. Forming technology helps to form powdered activated carbon into granules, which helps to reduce reactor pressure drop and dust pollution. However, after converting powdered activated carbon into shaped carbon at the millimeter or centimeter scale, the actual exposed specific surface area and active sites of activated carbon during the catalytic reaction are limited due to the existence of mass transfer resistance. The negative effects are insufficient sulfur storage space and low reaction activity, which is one of the reasons for the low sulfur capacity of currently commercial activated carbon-based desulfurizers.

[0004] The desulfurization mechanism of carbon materials has been widely verified. First, air containing water vapor passes through the carbon material, forming a thin water film on its surface. H2S gas is adsorbed on the carbon material surface and dissociates into H2S in the water film. - Ions. Simultaneously, oxygen is converted into adsorbed reactive oxygen free radicals on the surface of carbon materials with active sites. Then, the formed HS... -Ions are converted into elemental sulfur through reaction with reactive oxygen radicals. As the water film flows, the elemental sulfur moves and is eventually stored in the larger pores. Finally, the catalytic oxidation reaction ends and the catalyst becomes inactive once all pores are filled. The presence of the water film is a necessary condition for initiating the reaction; the slow release of the co-catalyst in the carbon matrix promotes H2S dissociation; and the mesopores provide space for the storage of elemental sulfur. These two aspects synergistically improve the catalytic oxidation performance. Therefore, an important strategy for designing and synthesizing highly efficient desulfurization catalysts should be to find a suitable molding method, create a large number of uniformly distributed alkaline sites, and construct a layered porous structure with a reasonable size distribution.

[0005] Chinese patent CN113522348A discloses an H2S removal agent, its preparation method, and its application. This H2S removal agent comprises a carrier and an active component, wherein the carrier is a manganese oxide molecular sieve, and the active component is an iron oxide. The H2S removal agent provided by this patent can be directly used to remove H2S from mixed gases at relatively low temperatures. It utilizes the special crystal structure of the active phase to achieve H2S purification through adsorption combined with catalytic conversion. It is low-cost, has high desulfurization precision, high sulfur capacity, and high single-pass conversion rate, which is conducive to industrial application.

[0006] Chinese patent CN102600850A discloses a regenerable adsorbent for H2S removal and its preparation method. The adsorbent consists of two parts: an active component and a support. The active component is an alkaline metal salt, and the support is a composite support with several mesoporous channel structures, composed of activated alumina and molecular sieves. This patent improves the utilization efficiency of the active component by adjusting the pore structure of the composite support in the adsorbent to have mesoporous structures with pore sizes of 2–20 nm and 20–50 nm, thereby extending the single-use time of the adsorbent and reducing the regeneration frequency, ultimately achieving the goal of reducing operating energy consumption in industrial applications.

[0007] While the catalysts disclosed in the above and other patents have good desulfurization effects, they also have certain drawbacks, such as complex preparation processes, high preparation costs, easy deactivation of catalysts, and unfavorable conditions for industrialization. Summary of the Invention

[0008] The purpose of this invention is to provide a modified activated carbon catalyst for the room-temperature catalytic oxidation of H2S, as well as its preparation and application. The catalyst preparation method is relatively simple, low-cost, and can achieve ultra-high sulfur capacity. Utilizing the characteristics of activated carbon such as high pore volume, large specific surface area, and rich surface chemistry, a co-catalyst is loaded to adjust surface properties, and pore modification is performed by combining it with ultrafine biomass powder, significantly improving the catalytic oxidation performance of H2S.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] A modified activated carbon catalyst for room temperature catalytic oxidation of H2S, wherein the modified activated carbon catalyst is composed of an activated carbon support and a co-catalyst, wherein the co-catalyst accounts for 2-20% of the mass percentage of the modified activated carbon catalyst.

[0011] The activated carbon carrier is composed of activated carbon and biomass, and the mass ratio of activated carbon to biomass is 4-19:1.

[0012] The biomass is selected from any one or more of straw, corn cobs, leaves, or wood chips.

[0013] Furthermore, the co-catalyst is selected from any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, zinc hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, or calcium oxide.

[0014] Furthermore, the activated carbon is selected from any one or more activated carbons used in water treatment, food processing, or gas purification and recovery.

[0015] Furthermore, the activated carbon carrier is cylindrical in shape, and extruding it into a cylindrical shape can meet the requirements of industrial applications, reducing pressure drop and dust pollution.

[0016] This invention also provides a method for preparing a modified activated carbon catalyst for the room-temperature catalytic oxidation of H2S, the specific steps of which are as follows:

[0017] S1. Preparation of activated carbon powder;

[0018] S2. Preparation of biomass powder;

[0019] S3. When the co-catalyst is soluble, the activated carbon powder obtained in step S1 and the biomass powder obtained in step S2 are mixed evenly, then deionized water and binder are added, stirred and mixed, extruded and shaped, dried and calcined to obtain the activated carbon carrier.

[0020] S4. Impregnate the activated carbon support obtained in step S3 with an equal volume of the co-catalyst, and dry to obtain the modified activated carbon catalyst.

[0021] S5. When the co-catalyst is a poorly soluble substance, the activated carbon powder obtained in step S1, the biomass powder obtained in step S2 and the co-catalyst are mixed evenly, then deionized water and binder are added, stirred and mixed, extruded and shaped, dried and calcined to obtain the modified activated carbon catalyst.

[0022] Further, in step S1, the specific steps for preparing activated carbon powder are as follows: the recovered activated carbon is dried at high temperature, ground and sieved to obtain activated carbon powder.

[0023] Furthermore, the activated carbon is selected from any one or more activated carbons used in water treatment, food processing, or gas purification and recovery.

[0024] The drying temperature is 80-90℃, and the drying time is 3-5 hours;

[0025] The sieve size is 100-200 mesh.

[0026] Furthermore, in step S2, the specific steps for preparing biomass powder are as follows: drying the biomass at high temperature, grinding and sieving to obtain biomass powder.

[0027] Furthermore, the biomass is selected from any one or more of straw, corn cobs, leaves, or sawdust;

[0028] The drying temperature is 80-90℃, and the drying time is 3-5 hours;

[0029] The sieve size is 50-300 mesh.

[0030] Furthermore, in step S3, the soluble co-catalyst is selected from any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, or potassium hydroxide.

[0031] Further, in step S3, the mass ratio of activated carbon powder to biomass powder is 4 to 19:1;

[0032] The mass ratio of activated carbon powder to deionized water is 0.5–1.5:1;

[0033] The mass ratio of activated carbon powder to binder is 1 to 9:1.

[0034] Further, in step S4, the mass ratio of the activated carbon support to the co-catalyst is 4 to 19:1;

[0035] The drying temperature is 70-90℃, and the drying time is 3-5 hours.

[0036] Furthermore, in step S5, the sparingly soluble co-catalyst is selected from any one or more of zinc hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, or calcium oxide.

[0037] Further, in step S5, the mass ratio of the activated carbon powder to the co-catalyst is 4 to 19:1;

[0038] The mass ratio of activated carbon powder to biomass powder is 4–19:1;

[0039] The mass ratio of activated carbon powder to deionized water is 0.5–1.5:1;

[0040] The mass ratio of activated carbon powder to binder is 1 to 9:1.

[0041] Furthermore, in steps S3 and S5, the binder is selected from any one or more of sodium carboxymethyl cellulose, bentonite, phenolic resin, and coal tar.

[0042] Furthermore, in steps S3 and S5, the specific steps of the extrusion molding are as follows: the extrusion is carried out at room temperature using a single screw extruder, with an extrusion rate of 0.1 to 0.3 m / min and a pipe diameter of 2 to 6 mm.

[0043] Furthermore, in steps S3 and S5, the drying temperature is 70-90°C and the drying time is 3-5 hours.

[0044] The roasting temperature is 400-800℃, and the roasting time is 2-4 hours.

[0045] Furthermore, the present invention also provides an application of a modified activated carbon catalyst for the room-temperature catalytic oxidation of H2S, wherein the modified activated carbon catalyst is industrially used for the room-temperature catalytic oxidation of H2S.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] (1) The preparation method of the present invention is simple and low in cost. The surface and pores of the recycled activated carbon can be restored by thermal regeneration. During the catalyst forming process, appropriate material ratios and forming methods are adopted. While modifying the pores, the formed catalyst has sufficient strength to meet the requirements of industrial applications and can achieve ultra-high sulfur capacity at room temperature.

[0048] (2) The present invention uses a suitable co-catalyst loading, which improves the surface chemistry of the catalyst, effectively enhances the adsorption and dissociation of reactants, and achieves long-term and efficient desulfurization in synergy with the well-developed pore structure.

[0049] (3) This invention uses ultrafine biomass particles as templates to form a macroporous structure, which greatly improves the mass transfer effect, makes it easier for gas to enter the interior of columnar activated carbon, reduces diffusion resistance, increases the contact probability between active sites and reactants, and is beneficial to the adsorption and activation of reactants. At the same time, more macropores can not only store moisture, providing a continuous H2S dissociation environment inside the catalyst, but also serve as sulfur storage space, extending the catalyst life.

[0050] (4) The preparation method of this invention is simple. Using low-cost recycled activated carbon as raw material, a catalyst with a certain shape and mechanical strength is obtained by adopting appropriate proportions and molding methods. The addition of co-catalyst effectively improves the continuous dissociation ability of H2S. Biomass ultrafine particles are used as template agents to modify the pores, forming a macroporous structure, which effectively reduces the diffusion resistance of gas molecules, making it easier for reactants to enter the interior of columnar activated carbon for adsorption and activation, effectively improving the utilization rate of the carbon matrix, and increasing the sulfur capacity by about 24%. The highest sulfur capacity of the catalyst reaches 1.23gH2S / gcatalyst, which can be used for low-temperature and high-efficiency removal of H2S in industry. Attached Figure Description

[0051] Figure 1 This is a scanning electron microscope image of the cross-section of the columnar activated carbon carrier prepared in Comparative Example 1 of this invention;

[0052] Figure 2 This is a scanning electron microscope image of the cross-section of the columnar activated carbon carrier prepared in Example 2 of the present invention;

[0053] Figure 3 This is a schematic diagram illustrating the macroporous gas-phase mass transfer promotion derived from the biomass ultrafine powder of this invention. Detailed Implementation

[0054] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0055] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0056] Example 1

[0057] This embodiment provides a modified activated carbon catalyst for the catalytic oxidation of H2S at room temperature. The modified activated carbon catalyst is composed of an activated carbon support and a co-catalyst, wherein the co-catalyst accounts for 2-20% of the mass percentage of the modified activated carbon catalyst.

[0058] The activated carbon carrier is composed of activated carbon and biomass, and the mass ratio of activated carbon to biomass is 4-19:1.

[0059] The biomass is selected from any one or more of straw, corn cobs, leaves, or wood chips.

[0060] In this embodiment, the co-catalyst is selected from any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, zinc hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, or calcium oxide.

[0061] In this embodiment, the activated carbon is selected from any one or more activated carbons used in water treatment, food processing, or gas purification and recovery.

[0062] In this embodiment, the activated carbon carrier is columnar in shape.

[0063] This embodiment also provides a method for preparing a modified activated carbon catalyst for the room temperature catalytic oxidation of H2S, the specific steps of which are as follows:

[0064] S1. Preparation of activated carbon powder;

[0065] S2. Preparation of biomass powder;

[0066] S3. When the co-catalyst is soluble, the activated carbon powder obtained in step S1 and the biomass powder obtained in step S2 are mixed evenly, then deionized water and binder are added, stirred and mixed, extruded and shaped, dried and calcined to obtain the activated carbon carrier.

[0067] S4. Impregnate the activated carbon support obtained in step S3 with an equal volume of the co-catalyst, and dry to obtain the modified activated carbon catalyst.

[0068] S5. When the co-catalyst is a poorly soluble substance, the activated carbon powder obtained in step S1, the biomass powder obtained in step S2 and the co-catalyst are mixed evenly, then deionized water and binder are added, stirred and mixed, extruded and shaped, dried and calcined to obtain the modified activated carbon catalyst.

[0069] In this embodiment, the specific steps for preparing activated carbon powder in step S1 are as follows: the recovered activated carbon is dried at high temperature, ground and sieved to obtain activated carbon powder.

[0070] In this embodiment, the activated carbon is selected from any one or more activated carbons used in water treatment, food processing, or gas purification and recovery.

[0071] The drying temperature is 80-90℃, and the drying time is 3-5 hours;

[0072] The sieve size is 100-200 mesh.

[0073] In this embodiment, the specific steps for preparing biomass powder in step S2 are as follows: the biomass is dried at high temperature, ground and sieved to obtain biomass powder.

[0074] In this embodiment, the biomass is selected from any one or more of straw, corn cobs, leaves, or wood chips;

[0075] The drying temperature is 80-90℃, and the drying time is 3-5 hours;

[0076] The sieve size is 50-300 mesh.

[0077] In this embodiment, in step S3, the soluble co-catalyst is selected from sodium carbonate, potassium carbonate, sodium hydroxide, or potassium hydroxide, or any one or more of these.

[0078] In this embodiment, in step S3, the mass ratio of activated carbon powder to biomass powder is 4 to 19:1;

[0079] The mass ratio of activated carbon powder to deionized water is 0.5–1.5:1;

[0080] The mass ratio of activated carbon powder to binder is 1 to 9:1.

[0081] In this embodiment, in step S4, the mass ratio of the activated carbon support to the co-catalyst is 4 to 19:1;

[0082] The drying temperature is 70-90℃, and the drying time is 3-5 hours.

[0083] In this embodiment, in step S5, the sparingly soluble co-catalyst is selected from any one or more of zinc hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, or calcium oxide.

[0084] In this embodiment, in step S5, the mass ratio of activated carbon powder to co-catalyst is 4-19:1;

[0085] The mass ratio of activated carbon powder to biomass powder is 4–19:1;

[0086] The mass ratio of activated carbon powder to deionized water is 0.5–1.5:1;

[0087] The mass ratio of activated carbon powder to binder is 1 to 9:1.

[0088] In this embodiment, in steps S3 and S5, the binder is selected from any one or more of sodium carboxymethyl cellulose, bentonite, phenolic resin, and coal tar.

[0089] In this embodiment, the specific steps of extrusion molding in steps S3 and S5 are as follows: a single screw extruder is used at room temperature, the extrusion rate is 0.1 to 0.3 m / min, and the pipe diameter is 2 to 6 mm.

[0090] In this embodiment, in steps S3 and S5, the drying temperature is 70-90°C and the drying time is 3-5 hours.

[0091] The roasting temperature is 400-800℃, and the roasting time is 2-4 hours.

[0092] Example 2

[0093] This embodiment provides a method for preparing a modified activated carbon catalyst for the room-temperature catalytic oxidation of H2S, the specific steps of which are as follows:

[0094] (1) Preparation of recycled activated carbon powder: The recycled activated carbon from food processing is dried at 80°C for 3 hours, ground and sieved to obtain 150-200 mesh recycled activated carbon powder;

[0095] (2) Preparation of biomass powder: Dry the wood chips at 80℃ for 3 hours, grind and sieve to obtain 80-100 mesh sawdust powder.

[0096] (3) Preparation of columnar activated carbon carrier: 22.5g of recycled activated carbon powder and 3g of sawdust powder were stirred and mixed evenly, and then 25g of deionized water and 7.5g of bentonite were added in sequence, stirred and mixed, and extruded to obtain columnar activated carbon with a diameter of 5mm. The columnar activated carbon was dried at 80℃ and calcined at 800℃ for 2 hours to obtain columnar activated carbon carrier.

[0097] (4) Preparation of modified columnar activated carbon catalyst: 20g columnar activated carbon support and 1g sodium carbonate were impregnated in equal volume and dried at 80℃ to obtain modified columnar activated carbon catalyst.

[0098] Activity testing of modified columnar activated carbon catalysts:

[0099] The modified columnar activated carbon catalyst was used to catalytically oxidize H2S. The modified columnar activated carbon catalyst was ground to 20-50 mesh (simulating industrial loading conditions). 0.5g of the modified columnar activated carbon catalyst was loaded into a quartz tube fixed-bed reactor with an inner diameter of 10mm. The reaction conditions were: inlet gas flow rate of 150ml / min, H2S concentration of 1000ppm, reaction temperature of 25℃, and oxygen content of 1% (v / v).

[0100] The reaction was stopped when the H2S outlet concentration reached 5% of the inlet concentration. The reaction time was 37.5 h, and the sulfur capacity was 1.02 g H2S / g catalyst.

[0101] Example 3

[0102] This embodiment provides a method for preparing a modified activated carbon catalyst for the room-temperature catalytic oxidation of H2S, the specific steps of which are as follows:

[0103] (1) Preparation of recycled activated carbon powder: The recycled activated carbon from food processing is dried at 80°C for 3 hours, ground and sieved to obtain 150-200 mesh recycled activated carbon powder;

[0104] (2) Preparation of biomass powder: Dry the wood chips at 80℃ for 3 hours, grind and sieve to obtain 80-100 mesh sawdust powder.

[0105] (3) Preparation of columnar activated carbon carrier: 22.5g of recycled activated carbon powder and 3g of sawdust powder were stirred and mixed evenly, and then 25g of deionized water and 7.5g of bentonite were added in sequence, stirred and mixed, and extruded to obtain columnar activated carbon with a diameter of 5mm. The columnar activated carbon was dried at 80℃ and calcined at 800℃ for 2 hours to obtain columnar activated carbon carrier.

[0106] (4) Preparation of modified columnar activated carbon catalyst: 20g columnar activated carbon support and 1g sodium hydroxide were impregnated in equal volume and dried at 80℃ to obtain modified columnar activated carbon catalyst.

[0107] Activity testing of modified columnar activated carbon catalysts:

[0108] The modified columnar activated carbon catalyst was used to catalytically oxidize H2S. The modified columnar activated carbon catalyst was ground to 20-50 mesh and 0.5 g of modified columnar activated carbon catalyst was packed into a quartz tube fixed bed reactor with an inner diameter of 10 mm. The reaction conditions were: inlet gas flow rate of 150 ml / min, H2S concentration of 1000 ppm, reaction temperature of 25℃, and oxygen content of 1% (v / v).

[0109] The reaction was stopped when the H2S outlet concentration reached 5% of the inlet concentration. The reaction time was 34 hours, and the sulfur capacity was 0.93 g H2S / g catalyst.

[0110] Example 4

[0111] This embodiment provides a method for preparing a modified activated carbon catalyst for the room-temperature catalytic oxidation of H2S, the specific steps of which are as follows:

[0112] (1) Preparation of recycled activated carbon powder: The recycled activated carbon from food processing is dried at 80°C for 3 hours, ground and sieved to obtain 150-200 mesh recycled activated carbon powder;

[0113] (2) Preparation of biomass powder: Dry the wood chips at 80℃ for 3 hours, grind and sieve to obtain 80-100 mesh sawdust powder.

[0114] (3) Preparation of modified columnar activated carbon catalyst: 22.5g of recycled activated carbon powder, 2g of magnesium oxide and 3g of sawdust powder were stirred and mixed evenly, and then 25g of deionized water and 7.5g of bentonite were added in sequence, stirred and mixed, and extruded to obtain columnar activated carbon with a diameter of 5mm. The columnar activated carbon was dried at 80℃ and calcined at 800℃ for 2 hours to obtain modified columnar activated carbon catalyst.

[0115] Activity testing of modified columnar activated carbon catalysts:

[0116] The modified columnar activated carbon catalyst was used to catalytically oxidize H2S. The modified columnar activated carbon catalyst was ground to 20-50 mesh and 0.5 g of modified columnar activated carbon catalyst was packed into a quartz tube fixed bed reactor with an inner diameter of 10 mm. The reaction conditions were: inlet gas flow rate of 150 ml / min, H2S concentration of 1000 ppm, reaction temperature of 25℃, and oxygen content of 1% (v / v).

[0117] The reaction was stopped when the H2S outlet concentration reached 5% of the inlet concentration. The reaction time was 45 hours, and the sulfur capacity was 1.23 g H2S / g catalyst.

[0118] Comparative Example 1

[0119] This comparative example provides a method for preparing an activated carbon catalyst without the addition of biomass, the specific steps of which are as follows:

[0120] (1) Preparation of recycled activated carbon powder: The recycled activated carbon from food processing is dried at 80°C for 3 hours, ground and sieved to obtain 150-200 mesh recycled activated carbon powder;

[0121] (2) Preparation of columnar activated carbon carrier: 22.5g of recycled activated carbon powder was mixed evenly with 25g of deionized water and 7.5g of bentonite, stirred and mixed, and extruded to obtain columnar activated carbon with a diameter of 5mm. The columnar activated carbon was dried at 80℃ and calcined at 800℃ for 2 hours to obtain columnar activated carbon carrier.

[0122] (3) Preparation of activated carbon catalyst: 20g of columnar activated carbon support and 1g of sodium carbonate were impregnated in equal volume and dried at 80℃ to obtain columnar activated carbon catalyst.

[0123] Catalytic performance test of columnar activated carbon:

[0124] The obtained columnar activated carbon catalyst was used to catalytically oxidize H2S. The columnar activated carbon catalyst was ground to 20-50 mesh and 0.5g of columnar activated carbon catalyst was packed into a quartz tube fixed bed reactor with an inner diameter of 10mm. The reaction conditions were: inlet gas flow rate of 150ml / min, H2S concentration of 1000ppm, reaction temperature of 25℃, and oxygen content of 1% (v / v).

[0125] The reaction was stopped when the H2S outlet concentration reached 5% of the inlet concentration. The reaction time was 30 hours, and the sulfur capacity was 0.82 g H2S / g catalyst.

[0126] Comparing Comparative Example 1 with Example 2, see Table 1 and Figure 1-2 , Figure 2The surface forms a macroporous structure due to the biomass powder, making it rougher. Therefore, adding biomass powder to columnar activated carbon can introduce an ordered macroporous structure, which can serve as a gas transport channel, reduce the diffusion resistance of the gas phase, and facilitate gas molecules to contact the deeper nanopores of the particles for adsorption and activation, thereby improving the utilization rate of the carbon matrix.

[0127] The modified catalyst introduced a higher proportion of macropores, but the micropores and mesopores did not change much. The room temperature desulfurization performance was improved by about 24%, which is related to the increase in porosity.

[0128] Table 1 summarizes the pore structure parameters of the columnar activated carbon carriers in Example 2 and Comparative Example 1.

[0129]

[0130] Comparative Example 2

[0131] This comparative example provides a method for preparing an activated carbon catalyst without the addition of a co-catalyst, the specific steps of which are as follows:

[0132] (1) Preparation of recycled activated carbon powder: The recycled activated carbon from food processing is dried at 80°C for 3 hours, ground and sieved to obtain 150-200 mesh recycled activated carbon powder;

[0133] (2) Preparation of biomass powder: Dry the wood chips at 80℃ for 3 hours, grind and sieve to obtain 80-100 mesh sawdust powder.

[0134] (3) Preparation of columnar activated carbon carrier: 22.5g of activated carbon powder and 3g of sawdust powder were stirred and mixed evenly, and then 20g of deionized water and 7.5g of bentonite were added in sequence, stirred and mixed, and extruded to obtain columnar activated carbon with a diameter of 5mm. The columnar activated carbon was dried at 80℃ and calcined at 800℃ for 2 hours to obtain columnar activated carbon catalyst.

[0135] Activity testing of columnar activated carbon catalysts:

[0136] The obtained columnar activated carbon catalyst was used to catalytically oxidize H2S. The columnar activated carbon catalyst was ground to 20-50 mesh and 0.5g of columnar activated carbon catalyst was packed into a quartz tube fixed bed reactor with an inner diameter of 10mm. The reaction conditions were: inlet gas flow rate of 150ml / min, H2S concentration of 1000ppm, reaction temperature of 25℃, and oxygen content of 1% (v / v).

[0137] The reaction was stopped when the H2S outlet concentration reached 5% of the inlet concentration. The reaction time was 5 hours, and the sulfur capacity was 0.15 g H2S / g catalyst.

[0138] Bentonite can act as a binder to give activated carbon a certain shape and mechanical strength, and it can also enhance the adsorption and alkalinity of activated carbon, giving columnar activated carbon a desulfurization performance of 0.15 g / g.

[0139] Comparing Comparative Example 2 with Examples 2-4, the addition of a co-catalyst altered the surface pH of the catalyst, indicating a change in its surface chemistry compared to the catalyst without co-catalyst. The columnar activated carbon support exhibited significantly improved catalytic performance after loading an appropriate amount of co-catalyst; the improved desulfurization performance demonstrates the improved surface chemistry of the catalyst. Furthermore, it indicates that the continuous dissociation of hydrogen sulfide is crucial for the reaction, and the type of co-catalyst also significantly influences the reaction. Basic salts such as Na₂CO₃ have high solubility in the water film and immediately form OH⁻. - These high concentrations of OH - While they aid in the dissociation of H₂S, they are readily consumed through acid-base neutralization reactions. The differences between these soluble bases may depend on their basicity or the rate of their neutralization reaction with H₂S. In contrast, basic magnesium oxide is partially soluble in water and can continuously release OH⁻. - This promotes the dissociation of H2S within a certain period of time, thus greatly improving the utilization rate of magnesium oxide and achieving the highest removal capacity.

[0140] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A modified activated carbon catalyst for the room-temperature catalytic oxidation of H2S, characterized in that, The modified activated carbon catalyst is composed of an activated carbon support and a co-catalyst, wherein the co-catalyst accounts for 2-20% of the mass percentage of the modified activated carbon catalyst. The activated carbon carrier is composed of activated carbon and biomass, and the mass ratio of activated carbon to biomass is 4~19:1; The biomass is selected from any one or more of straw, corn cobs, leaves or sawdust; The co-catalyst is selected from any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, zinc hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, or calcium oxide. The biomass is used as a template agent to form a macroporous structure; The modified activated carbon catalyst is used industrially for the catalytic oxidation of H2S at room temperature. The steps of the preparation method of the modified activated carbon catalyst for the room temperature catalytic oxidation of H2S are as follows: S1. Preparation of activated carbon powder; S2. Preparation of biomass powder; S3. When the co-catalyst is soluble, the activated carbon powder obtained in step S1 and the biomass powder obtained in step S2 are mixed evenly, then deionized water and binder are added, stirred and mixed, extruded and shaped, dried and calcined to obtain the activated carbon carrier. S4. Impregnate the activated carbon support obtained in step S3 with an equal volume of the co-catalyst, and dry to obtain the modified activated carbon catalyst. S5. When the co-catalyst is a poorly soluble substance, the activated carbon powder obtained in step S1, the biomass powder obtained in step S2 and the co-catalyst are mixed evenly, then deionized water and binder are added, stirred and mixed, extruded and shaped, dried and calcined to obtain the modified activated carbon catalyst.

2. The modified activated carbon catalyst for room temperature catalytic oxidation of H2S according to claim 1, characterized in that, The activated carbon is selected from any one or more activated carbons used in water treatment, food processing, or gas purification and recovery.

3. The modified activated carbon catalyst for room temperature catalytic oxidation of H2S according to claim 1, characterized in that, In step S1, the specific steps for preparing activated carbon powder are as follows: the recovered activated carbon is dried at high temperature, ground and sieved to obtain activated carbon powder. The activated carbon is selected from any one or more types of activated carbon used in water treatment, food processing, or gas purification and recovery. The drying temperature is 80-90℃, and the drying time is 3-5 hours; The sieve size is 100-200 mesh.

4. The modified activated carbon catalyst for room temperature catalytic oxidation of H2S according to claim 1, characterized in that, In step S2, the specific steps for preparing biomass powder are as follows: the biomass is dried at high temperature, ground and sieved to obtain biomass powder; The biomass is selected from any one or more of straw, corn cobs, leaves or sawdust; The drying temperature is 80-90℃, and the drying time is 3-5 hours; The sieve size is 50-300 mesh.

5. The modified activated carbon catalyst for room temperature catalytic oxidation of H2S according to claim 1, characterized in that, In step S3, the soluble co-catalyst is selected from any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, or potassium hydroxide; The mass ratio of activated carbon powder to biomass powder is 4~19:1; The mass ratio of activated carbon powder to deionized water is 0.5~1.5:1; The mass ratio of activated carbon powder to binder is 1~9:1; In step S4, the mass ratio of the activated carbon support to the co-catalyst is 4~19:1; The drying temperature is 70~90℃, and the drying time is 3-5 hours.

6. The modified activated carbon catalyst for room temperature catalytic oxidation of H2S according to claim 1, characterized in that, In step S5, the sparingly soluble co-catalyst is selected from any one or more of zinc hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, or calcium oxide; The mass ratio of activated carbon powder to co-catalyst is 4~19:1; The mass ratio of activated carbon powder to biomass powder is 4~19:1; The mass ratio of activated carbon powder to deionized water is 0.5~1.5:1; The mass ratio of activated carbon powder to binder is 1~9:

1.

7. The modified activated carbon catalyst for room temperature catalytic oxidation of H2S according to claim 1, characterized in that, In steps S3 and S5, the binder is selected from any one or more of sodium carboxymethyl cellulose, bentonite, phenolic resin, and coal tar. The specific steps of the extrusion molding are as follows: a single screw extruder is used at room temperature, the extrusion rate is 0.1~0.3m / min, and the pipe diameter is 2~6mm; The drying temperature is 70~90℃, and the drying time is 3-5 hours; The roasting temperature is 400~800℃, and the roasting time is 2~4 hours.

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