A highly efficient desulfurizing agent, its preparation method, and its application in the desulfurization of heavy naphtha.

Abstract

This invention relates to the field of petrochemical catalytic desulfurization technology, specifically disclosing a high-efficiency desulfurizing agent, its preparation method, and its application in the desulfurization of heavy naphtha. The desulfurizing agent provided by this invention has a "two-level" metal active center. The first level is a cobalt center in biochar, and the second level is a nickel-copper bimetallic center introduced through impregnation on the surface of a composite carrier. The desulfurizing agent provided by this invention has excellent desulfurization effect. Under conditions of 140°C and no hydrogen, it can simultaneously remove inorganic sulfur such as hydrogen sulfide and organic sulfur such as thiols, thioethers, and thiophenes from heavy naphtha obtained by hydrocracking of heavy diesel oil, wax oil, or mixed diesel and wax oil, reducing the total sulfur content from 25-40 μg·g. ‑1 Reduced to 0.2 μg·g ‑1 The following methods can effectively protect bimetallic (multimetallic) reforming catalysts from sulfur poisoning, and the preparation process is green and controllable, making it suitable for large-scale industrial applications.

Description

Technical Field

[0001] This invention relates to the field of petrochemical catalytic desulfurization technology, specifically to a high-efficiency desulfurizing agent, its preparation method, and its application in the desulfurization of heavy naphtha. Background Technology

[0002] Catalytic reforming is a core process in the oil refining industry for achieving the "reducing oil consumption and increasing chemical production" strategy and producing high-octane gasoline and aromatics such as benzene, toluene, and xylene (BTX). The quality of the feedstock directly determines the operating efficiency of the unit and the economic benefits of the products. With the increasing trend towards heavier and lower-quality refining feedstocks, heavy naphtha obtained through hydrocracking of heavy diesel, wax oil, or blended diesel and wax oil has become the mainstream feedstock for reforming units due to its high aromatic content and high resource utilization rate. However, the sulfur forms in this type of heavy naphtha are complex and diverse, with residual sulfur content of 5–10 μg·g⁻¹. -1 Inorganic sulfur such as hydrogen sulfide, and 20–30 μg·g -1 Organic sulfur compounds such as thiols, thioethers, and thiophenes are present, with the total sulfur content maintained at 25–40 μg·g. -1 This poses a serious threat to the core of the reforming process – bimetallic (multimetallic) reforming catalysts (such as platinum-rhenium and platinum-iridium catalysts).

[0003] Bimetallic (multimetallic) reforming catalysts exhibit extreme sensitivity to sulfur, a recognized technical challenge in the industry. Industrial practice and research data show that when the sulfur content of the feedstock exceeds 0.5 μg·g... -1 When sulfur compounds rapidly occupy the active sites of the catalyst and form irreversible adsorption, the catalyst becomes poisoned and deactivated: the sulfur content reaches 1 μg·g -1 At that time, the catalyst activity decreased by more than 10%, and the liquid yield and hydrogen production decreased significantly; the sulfur content increased to 1.5 μg·g -1 When catalyst activity declines by more than 20%, its lifespan is shortened by nearly half, requiring frequent shutdowns for catalyst replacement and resulting in significant economic losses. Therefore, a desulfurization protection bed is installed before the reforming unit to reduce the total sulfur content of heavy naphtha to 0.5 μg·g. -1 The following ultra-deep desulfurization is an essential prerequisite for ensuring the efficient, stable, and long-term operation of the reforming unit.

[0004] Although various desulfurizing agents have been developed using existing technologies, many bottlenecks remain insurmountable in areas such as active component design, carrier structure optimization, environmental friendliness of preparation processes, and adaptability to reaction conditions. These limitations prevent them from simultaneously meeting the industrial demands for "ultra-deep desulfurization + hydrogen-free low-temperature + long lifespan + green environmental protection." For example, the nickel-copper bimetallic + rare earth oxide desulfurizing agent disclosed in Chinese patent CN114752405B has limited adsorption and activation capabilities for thiophene-based nonpolar organic sulfur due to the lack of electronic synergistic effects from the active components. Similarly, US patent US4446005A, using a single nickel-based adsorption catalyst, can only selectively remove some sulfides and cannot simultaneously meet the complex removal requirements of high-content inorganic and organic sulfur. Furthermore, traditional active component systems generally lack metal loss inhibition designs: most desulfurizing agents use only rare earth oxides as additives without combining them with chelating agents to form dual protection, resulting in metal active component leaching amounts generally exceeding 0.02 μg·g⁻¹. -1 This not only contaminates downstream products but may also exacerbate the risk of reforming catalyst poisoning.

[0005] Existing desulfurizing agents suffer from technical defects such as insufficient synergy of active components, significant side effects of zinc-containing systems, unreasonable carrier structure design, poor environmental friendliness of preparation processes, and imbalanced overall performance. These shortcomings prevent them from meeting the integrated requirements of reforming desulfurization protection beds for "hydrogen-free, low-temperature, ultra-deep desulfurization of high-sulfur feedstock + no metal loss + long lifespan + green environmental protection." Therefore, developing a synergistic innovation technology solution based on "zinc-free multi-active components - modified composite carrier - integrated preparation process" is crucial to overcoming existing technical bottlenecks and ensuring the efficient operation of reforming units and promoting the green and low-carbon development of the refining and chemical industry. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a highly efficient desulfurizing agent, its preparation method, and its application in the desulfurization of heavy naphtha. The desulfurizing agent provided by the present invention can achieve simultaneous ultra-deep removal of inorganic and organic sulfur from high-sulfur heavy naphtha at 140°C under hydrogen-free conditions. The preparation process is green and efficient, and effectively protects the bimetallic (multimetallic) reforming catalyst.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a high-efficiency oil desulfurizing agent, comprising the following steps:

[0009] S1. Preparation of composite carrier

[0010] The composite modified biochar, molecular sieve, graphene, pseudoboehmite binder and deionized water were kneaded evenly and then extruded into strips, which were then dried and calcined to obtain the composite carrier.

[0011] In this step, the preparation method of the composite modified biochar is as follows: straw powder, cobalt salt and sodium borohydride are added to deionized water, stirred and adsorbed, then filtered, washed and dried, and calcined under a nitrogen atmosphere to obtain composite modified biochar.

[0012] In the technical solution disclosed in this invention, the mass ratio of straw powder, cobalt salt and sodium borohydride is 20-40:5-10:10-15.

[0013] In the technical solution disclosed in this invention, under nitrogen atmosphere protection, the temperature is raised to 550-650℃ at a heating rate of 5-10℃ / min, and then kept at the temperature for calcination for 1-3 hours to obtain composite modified biochar.

[0014] In this step, the mass ratio of the composite modified biochar, molecular sieve, graphene, pseudoboehmite, and deionized water is 25-40:10-15:4-8:15-25:20-30.

[0015] In this step, an extrusion machine is used to form strips with a diameter of 2-4 mm.

[0016] In this step, the molded wet strip is dried at 100-120℃ for 4-8 hours, and then heated to 450-550℃ at 2-5℃ / min in an air or nitrogen atmosphere and calcined for 3-5 hours to obtain the composite carrier.

[0017] In this step, in the aqueous phase, the strong reducing properties of sodium borohydride first reduce cobalt ions to metallic cobalt particles. At the same time, straw powder, with its rich porous structure and surface functional groups, acts as a dispersion matrix to adsorb and load the newly formed metallic cobalt particles and boron-containing compounds produced by the hydrolysis of sodium borohydride, forming a precursor. Subsequently, the precursor is dried and calcined to obtain boron and cobalt-doped modified biochar.

[0018] Due to its unique electron-deficient properties, boron atoms, when incorporated into the biochar framework, "pull" electrons from neighboring cobalt elements, resulting in a decrease in the electron cloud density of the surrounding area. The cobalt centers, having lost some electrons, exhibit improved adsorption performance for sulfur atoms (highly electronegative and electron-rich) in sulfur-containing compounds. Simultaneously, the incorporation of boron atoms into the carbon lattice causes local lattice distortion and structural defects. These defects can serve as anchoring sites for cobalt, effectively preventing the migration and aggregation of cobalt during high-temperature calcination and use, thus enhancing the stability of the active component.

[0019] In this step, graphene, with its high conductivity and two-dimensional sheet structure, can serve as an electron conduction network to promote electron transfer during the reaction process.

[0020] In this step, boehmite, as a binder and active alumina precursor, can provide a microporous structure.

[0021] S2. Preparation of amino-modified composite carriers

[0022] The composite carrier was dispersed in an aqueous ethanol solution, and then an aminosilane coupling agent was added. After stirring, the mixture was filtered, washed, and dried to obtain the amino-modified composite carrier.

[0023] In this step, the mass ratio of the composite carrier to the aminosilane coupling agent is 20-40:1-3. For example, 20:1, 20:2, 20:3, 30:1, 30:2, 35:1, 40:1, and 40:3 can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] In this step, by grafting amino groups onto the surface of the composite support, the affinity of the support for the subsequent metal salt solution is enhanced, and the metal ions can be effectively anchored through coordination to prevent their migration and aggregation during subsequent drying and calcination processes, thereby ensuring the high dispersion of the active metal components.

[0025] S3, Preparation of desulfurizing agent precursor

[0026] Nickel and copper salts were dissolved in deionized water, and disodium ethylenediaminetetraacetate (EDTA) was added as a chelating agent. The mixture was stirred until homogeneous, and then an amino-modified composite carrier was added for impregnation. After impregnation, the mixture was filtered, washed, and dried to obtain the desulfurizing agent precursor.

[0027] In this step, the mass ratio of nickel salt, copper salt, disodium ethylenediaminetetraacetate, and amino-modified composite carrier is 4-8:1-2:5-10:10-15.

[0028] In this step, the immersion temperature is 40-60℃ and the immersion time is 4-8 hours.

[0029] S4. Preparation of desulfurizing agent

[0030] The desulfurizing agent precursor is placed in a nitrogen atmosphere, and formaldehyde water vapor is introduced for in-situ reduction. After constant temperature curing, a high-efficiency desulfurizing agent is obtained.

[0031] In this step, the nitrogen space velocity is 400-600 h⁻¹. -1 The vapor space velocity of formaldehyde is 200-300 h⁻¹. -1 The volume fraction of formaldehyde in formaldehyde water vapor is 5-10%.

[0032] In this step, the in-situ reduction temperature is 180-220℃, and the in-situ reduction time is 3-4 hours.

[0033] In this step, the temperature for constant temperature curing is 120-150℃, and the curing time is 2-3 hours.

[0034] In this step, formaldehyde water vapor is introduced under inert nitrogen protection. The formaldehyde decomposes under heating conditions to produce a reducing atmosphere, which can gently reduce the nickel and copper ions anchored on the surface of the composite carrier to low-valence active metal elements, thereby increasing the content of active metal elements on the surface of the desulfurizer and thus enhancing the desulfurizer's ability to treat heavy naphtha.

[0035] Secondly, the present invention provides a highly efficient desulfurizing agent prepared by the above-described preparation method.

[0036] Thirdly, the present invention also provides the application of the above-mentioned high-efficiency desulfurizing agent in the desulfurization of heavy naphtha.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The desulfurizer provided by the present invention can achieve simultaneous ultra-deep removal of inorganic sulfur and organic sulfur in high-sulfur heavy naphtha at 140°C and under hydrogen-free conditions. The preparation process is green and efficient, and effectively protects the bimetallic (multi-metal) reforming catalyst.

[0039] (2) The boron and cobalt-doped modified biochar provided by the present invention has boron atoms with unique electron-deficient characteristics. After being doped into the biochar framework, boron atoms "pull" electrons from the neighboring cobalt elements, resulting in a decrease in the electron cloud density in the surrounding area. The cobalt center that has been partially pulled away with electrons has improved the adsorption performance of sulfur atoms (high electronegativity and rich in electrons) in sulfur-containing compounds. At the same time, the doping of boron atoms into the carbon lattice will cause local lattice distortion and generate structural defects. These defects can serve as anchoring sites for cobalt, effectively preventing the migration and aggregation of cobalt during high-temperature calcination and use, and enhancing the stability of the active components.

[0040] (3) The desulfurizing agent provided by the present invention is a “two-level” metal active center. The first level is the cobalt center in biochar, and the second level is the nickel-copper bimetallic center introduced by impregnation on the surface of the composite carrier. Compared with impregnating cobalt, nickel and copper at the same time, it has a better desulfurization effect. The reason may be that the “two-level” metal active center produces an interface synergistic effect, and the division of labor and cooperation result in a better desulfurization effect.

[0041] (4) This invention uses formaldehyde water vapor as a reducing medium to reduce metal chelates in situ at 180-220℃, avoiding the safety risks and secondary pollution of traditional hydrogen reduction, and achieving simultaneous reduction and curing. Attached Figure Description

[0042] Figure 1 A photograph of the desulfurizing agent prepared in Example 1;

[0043] Figure 2 The graph shows the relationship between the desulfurization efficiency and operating time of the desulfurizing agent prepared in Example 1 in industrial applications. Detailed Implementation

[0044] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0045] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0046] The straw powder used in this embodiment of the invention is wheat straw powder with a mesh size of 80; the molecular sieve is a 13X type molecular sieve with a mesh size of 250 and a specific surface area of ​​550 m². 2 / g; the graphene has 5 layers and a sheet diameter of 8μm; the solid content of boehmite is 70%.

[0047] Example 1

[0048] A method for preparing a high-efficiency desulfurizing agent includes the following steps:

[0049] S1. Add 40g of straw powder, 10g of cobalt nitrate and 15g of sodium borohydride to 400mL of deionized water, stir and adsorb for 6h, then filter, wash and dry, heat to 600℃ at a heating rate of 10℃ / min under nitrogen atmosphere, and then keep warm and calcine for 2h to obtain composite modified biochar.

[0050] S2. 40g of composite modified biochar, 15g of molecular sieve, 8g of graphene, 25g of pseudo-boehmite binder and 30g of deionized water were kneaded evenly and extruded into strips. The formed wet strips were dried at 120℃ for 4h, and then calcined in a nitrogen atmosphere at a rate of 5℃ / min to 500℃ for 4h to obtain the composite carrier.

[0051] S3. Disperse 20g of the composite carrier in 400mL of ethanol-water solution (ethanol to water volume ratio of 4:1), then add 1g of silane coupling agent KH550, stir, filter, wash and dry to obtain amino-modified composite carrier.

[0052] S4. Dissolve 4g of nickel nitrate and 1g of copper nitrate in 150mL of deionized water, add 5g of chelating agent disodium ethylenediaminetetraacetate, stir evenly, then add 10g of amino-modified composite carrier, and impregnate at 50℃ for 6h. After impregnation, filter, wash and dry to obtain the desulfurizing agent precursor.

[0053] S5. Place the desulfurizing agent precursor in a nitrogen atmosphere and introduce formaldehyde water vapor, wherein the nitrogen space velocity is 500 h⁻¹. -1 The vapor space velocity of formaldehyde is 300 h⁻¹. -1The formaldehyde volume fraction in the formaldehyde water vapor is 10%. It is reduced in situ at 180℃ for 4 hours, and then cured at a constant temperature of 120℃ for 3 hours to obtain the desulfurizing agent.

[0054] Example 2

[0055] A method for preparing a high-efficiency desulfurizing agent includes the following steps:

[0056] S1. Add 20g of straw powder, 5g of cobalt nitrate and 10g of sodium borohydride to 400mL of deionized water, stir and adsorb for 6h, then filter, wash and dry, heat to 600℃ at a heating rate of 10℃ / min under nitrogen atmosphere, and then keep warm and calcine for 2h to obtain composite modified biochar.

[0057] S2. 25g of composite modified biochar, 10g of molecular sieve, 4g of graphene, 15g of pseudo-boehmite binder and 20g of deionized water were kneaded evenly and extruded into strips. The formed wet strips were dried at 120℃ for 4h, and then calcined in a nitrogen atmosphere at a rate of 5℃ / min to 500℃ for 4h to obtain the composite carrier.

[0058] S3. Disperse 20g of the composite carrier in 400mL of ethanol-water solution (ethanol to water volume ratio of 4:1), then add 2g of silane coupling agent KH550, stir, filter, wash and dry to obtain amino-modified composite carrier.

[0059] S4. Dissolve 6g of nickel nitrate and 1.5g of copper nitrate in 150mL of deionized water, add 8g of chelating agent disodium ethylenediaminetetraacetate, stir well, then add 12g of amino-modified composite carrier, and impregnate at 50℃ for 6h. After impregnation, filter, wash and dry to obtain the desulfurizing agent precursor.

[0060] S5. Place the desulfurizing agent precursor in a nitrogen atmosphere and introduce formaldehyde water vapor, wherein the nitrogen space velocity is 500 h⁻¹. -1 The vapor space velocity of formaldehyde is 300 h⁻¹. -1 The formaldehyde volume fraction in the formaldehyde water vapor is 10%. It is reduced in situ at 180℃ for 4 hours, and then cured at a constant temperature of 120℃ for 3 hours to obtain the desulfurizing agent.

[0061] Example 3

[0062] A method for preparing a high-efficiency desulfurizing agent includes the following steps:

[0063] S1. Add 28g of straw powder, 8g of cobalt nitrate and 12g of sodium borohydride to 400mL of deionized water, stir and adsorb for 6h, then filter, wash and dry, heat to 600℃ at a heating rate of 10℃ / min under nitrogen atmosphere, and then keep at the temperature for 2h to obtain composite modified biochar.

[0064] S2. 32g of composite modified biochar, 12g of molecular sieve, 6g of graphene, 20g of pseudo-boehmite binder and 25g of deionized water were kneaded evenly and extruded into strips. The formed wet strips were dried at 120℃ for 4h, and then calcined in a nitrogen atmosphere at a rate of 5℃ / min to 500℃ for 4h to obtain the composite carrier.

[0065] S3. Disperse 25g of the composite carrier in 400mL of ethanol-water solution (ethanol to water volume ratio of 4:1), then add 3g of silane coupling agent KH550, stir, filter, wash and dry to obtain amino-modified composite carrier.

[0066] S4. Dissolve 8g of nickel nitrate and 2g of copper nitrate in 150mL of deionized water, add 10g of chelating agent disodium ethylenediaminetetraacetate, stir evenly, then add 15g of amino-modified composite carrier, and impregnate at 50℃ for 6h. After impregnation, filter, wash and dry to obtain the desulfurizing agent precursor.

[0067] S5. Place the desulfurizing agent precursor in a nitrogen atmosphere and introduce formaldehyde water vapor, wherein the nitrogen space velocity is 500 h⁻¹. -1 The vapor space velocity of formaldehyde is 300 h⁻¹. -1 The formaldehyde volume fraction in the formaldehyde water vapor is 10%. It is reduced in situ at 180℃ for 4 hours, and then cured at a constant temperature of 120℃ for 3 hours to obtain the desulfurizing agent.

[0068] Comparative Example 1

[0069] A method for preparing a high-efficiency desulfurizing agent includes the following steps:

[0070] S1. Dry 40g of straw powder in an oven, then heat it to 600℃ at a heating rate of 10℃ / min under a nitrogen atmosphere, and then keep it at that temperature for 2 hours to obtain biochar.

[0071] S2. 40g biochar, 15g molecular sieve, 8g graphene, 25g pseudoboehmite binder and 30g deionized water are kneaded evenly and then extruded into strips. The formed wet strips are dried at 120℃ for 4h, and then calcined in a nitrogen atmosphere at a rate of 5℃ / min to 500℃ for 4h to obtain the composite carrier.

[0072] S3. Disperse 20g of the composite carrier in 400mL of ethanol-water solution (ethanol to water volume ratio of 4:1), then add 1g of silane coupling agent KH550, stir, filter, wash and dry to obtain amino-modified composite carrier.

[0073] S4. Dissolve 4g of nickel nitrate and 1g of copper nitrate in 150mL of deionized water, add 5g of chelating agent disodium ethylenediaminetetraacetate, stir evenly, then add 10g of amino-modified composite carrier, and impregnate at 50℃ for 6h. After impregnation, filter, wash and dry to obtain the desulfurizing agent precursor.

[0074] S5. Place the desulfurizing agent precursor in a nitrogen atmosphere and introduce formaldehyde water vapor, wherein the nitrogen space velocity is 500 h⁻¹. -1 The vapor space velocity of formaldehyde is 300 h⁻¹. -1 The formaldehyde volume fraction in the formaldehyde water vapor is 10%. It is reduced in situ at 180℃ for 4 hours, and then cured at a constant temperature of 120℃ for 3 hours to obtain the desulfurizing agent.

[0075] Compared to Example 1, no doping treatment was performed on the biochar in Comparative Example 1.

[0076] Comparative Example 2

[0077] A method for preparing a high-efficiency desulfurizing agent includes the following steps:

[0078] S1. Add 40g of straw powder and 15g of sodium borohydride to 400mL of deionized water, stir and adsorb for 6h, then filter, wash and dry, heat to 600℃ at a heating rate of 10℃ / min under nitrogen atmosphere, and then keep warm and calcine for 2h to obtain composite modified biochar.

[0079] S2. 40g of composite modified biochar, 15g of molecular sieve, 8g of graphene, 25g of pseudo-boehmite binder and 30g of deionized water were kneaded evenly and extruded into strips. The formed wet strips were dried at 120℃ for 4h, and then calcined in a nitrogen atmosphere at a rate of 5℃ / min to 500℃ for 4h to obtain the composite carrier.

[0080] S3. Disperse 20g of the composite carrier in 400mL of ethanol-water solution (ethanol to water volume ratio of 4:1), then add 1g of silane coupling agent KH550, stir, filter, wash and dry to obtain amino-modified composite carrier.

[0081] S4. Dissolve 4g of nickel nitrate and 1g of copper nitrate in 150mL of deionized water, add 5g of chelating agent disodium ethylenediaminetetraacetate, stir evenly, then add 10g of amino-modified composite carrier, and impregnate at 50℃ for 6h. After impregnation, filter, wash and dry to obtain the desulfurizing agent precursor.

[0082] S5. Place the desulfurizing agent precursor in a nitrogen atmosphere and introduce formaldehyde water vapor, wherein the nitrogen space velocity is 500 h⁻¹. -1 The vapor space velocity of formaldehyde is 300 h⁻¹. -1The formaldehyde volume fraction in the formaldehyde water vapor is 10%. It is reduced in situ at 180℃ for 4 hours, and then cured at a constant temperature of 120℃ for 3 hours to obtain the desulfurizing agent.

[0083] Compared to Comparative Example 2 and Example 1, the biochar was not treated with cobalt doping.

[0084] Comparative Example 3

[0085] A method for preparing a high-efficiency desulfurizing agent includes the following steps:

[0086] S1. Add 40g of straw powder and 10g of cobalt nitrate to 400mL of deionized water, stir and adsorb for 6h, then filter, wash and dry, heat to 600℃ at a heating rate of 10℃ / min under nitrogen atmosphere, and then keep warm and calcine for 2h to obtain composite modified biochar.

[0087] S2. 40g of composite modified biochar, 15g of molecular sieve, 8g of graphene, 25g of pseudo-boehmite binder and 30g of deionized water were kneaded evenly and extruded into strips. The formed wet strips were dried at 120℃ for 4h, and then calcined in a nitrogen atmosphere at a rate of 5℃ / min to 500℃ for 4h to obtain the composite carrier.

[0088] S3. Disperse 20g of the composite carrier in 400mL of ethanol-water solution (ethanol to water volume ratio of 4:1), then add 1g of silane coupling agent KH550, stir, filter, wash and dry to obtain amino-modified composite carrier.

[0089] S4. Dissolve 4g of nickel nitrate and 1g of copper nitrate in 150mL of deionized water, add 5g of chelating agent disodium ethylenediaminetetraacetate, stir evenly, then add 10g of amino-modified composite carrier, and impregnate at 50℃ for 6h. After impregnation, filter, wash and dry to obtain the desulfurizing agent precursor.

[0090] S5. Place the desulfurizing agent precursor in a nitrogen atmosphere and introduce formaldehyde water vapor, wherein the nitrogen space velocity is 500 h⁻¹. -1 The vapor space velocity of formaldehyde is 300 h⁻¹. -1 The formaldehyde volume fraction in the formaldehyde water vapor is 10%. It is reduced in situ at 180℃ for 4 hours, and then cured at a constant temperature of 120℃ for 3 hours to obtain the desulfurizing agent.

[0091] Compared to Comparative Example 3 and Example 1, the biochar was not treated with boron doping.

[0092] Comparative Example 4

[0093] A method for preparing a high-efficiency desulfurizing agent includes the following steps:

[0094] S1. Add 40g of straw powder and 15g of sodium borohydride to 400mL of deionized water, stir and adsorb for 6h, then filter, wash and dry, heat to 600℃ at a heating rate of 10℃ / min under nitrogen atmosphere, and then keep warm and calcine for 2h to obtain composite modified biochar.

[0095] S2. 40g of composite modified biochar, 15g of molecular sieve, 8g of graphene, 25g of pseudo-boehmite binder and 30g of deionized water were kneaded evenly and extruded into strips. The formed wet strips were dried at 120℃ for 4h, and then calcined in a nitrogen atmosphere at a rate of 5℃ / min to 500℃ for 4h to obtain the composite carrier.

[0096] S3. Disperse 20g of the composite carrier in 400mL of ethanol-water solution (ethanol to water volume ratio of 4:1), then add 1g of silane coupling agent KH550, stir, filter, wash and dry to obtain amino-modified composite carrier.

[0097] S4. Dissolve 4g of nickel nitrate, 2.5g of cobalt nitrate and 1g of copper nitrate in 150mL of deionized water, add 5g of chelating agent disodium ethylenediaminetetraacetate, stir evenly, then add 10g of amino-modified composite carrier, and impregnate at 50℃ for 6h. After impregnation, filter, wash and dry to obtain the desulfurizing agent precursor.

[0098] S5. Place the desulfurizing agent precursor in a nitrogen atmosphere and introduce formaldehyde water vapor, wherein the nitrogen space velocity is 500 h⁻¹. -1 The vapor space velocity of formaldehyde is 300 h⁻¹. -1 The formaldehyde volume fraction in the formaldehyde water vapor is 10%. It is reduced in situ at 180℃ for 4 hours, and then cured at a constant temperature of 120℃ for 3 hours to obtain the desulfurizing agent.

[0099] Compared with Example 1, Comparative Example 4 uses cobalt, nickel and copper to simultaneously impregnate in step S4.

[0100] The desulfurizers prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance testing. The specific steps are as follows:

[0101] Take 50 mL of desulfurizing agent and fill it into the middle constant temperature zone of a stainless steel reactor with an inner diameter of 20 mm × 500 mm (length). Then fill both ends of the stainless steel reactor with Φ3 mm inert ceramic balls and connect the stainless steel reactor to the desulfurization device for performance evaluation test: (1) Test raw materials: heavy naphtha raw material produced by hydrocracking (total sulfur 32 μg·g -1 Of which hydrogen sulfide was 8 μg·g -1 Thiol 6 μg·g -1 Thiophene 18 μg·g -1(2) Test conditions: Simulate the desulfurization process conditions of heavy naphtha in industrial plants, namely desulfurization temperature 140℃, pressure 0.20MPa, and feed space velocity 12h. -1 During the evaluation process, the content of sulfur in the form at the outlet of the stainless steel reactor was analyzed every 1 hour. When the total sulfur content at the outlet of the stainless steel reactor exceeded 0.5 μg·g... -1 If it is determined that the sulfur has been penetrated, the desulfurization test is stopped, the desulfurizing agent is removed, and the sulfur capacity of the desulfurizing agent is analyzed.

[0102] The test results are shown in Table 1.

[0103] Table 1 Performance test results for different groups

[0104]

[0105] As can be seen from Table 1, compared with the desulfurizers prepared in Comparative Examples 1-4, the high-efficiency desulfurizer prepared in this invention not only has a good removal effect on sulfides, but also has a strong ability to remove mercaptans and thiophenes, and can achieve simultaneous ultra-deep removal of inorganic sulfur and organic sulfur.

[0106] A physical image of the desulfurizing agent prepared in Example 1 of this invention is shown below. Figure 1 As shown.

[0107] The desulfurizing agent prepared in Example 1 of this invention was applied to the reforming desulfurization protection bed of a 4 million tons / year wax oil hydrocracking unit in a petrochemical company. The feedstock was heavy naphtha (total sulfur 28-38 μg·g). -1 Of which, inorganic sulfur is 6–9 μg·g -1 Organic sulfur 22–29 μg·g -1 (Organic sulfur content 75%–79%). The reaction was carried out at a temperature of 140℃, a pressure of 0.1–0.2 MPa, and a space velocity of 10–14 h⁻¹. -1 Under hydrogen-free operating conditions, the total sulfur content of the desulfurized product remained stable at 0.1–0.4 μg·g⁻¹. -1 The system fully meets the feed requirements for downstream platinum-rhenium bimetallic reforming catalysts. The unit has been operating stably for 15 months, with no significant decline in reforming catalyst activity. Liquid yield has increased by 4.5% compared to before use, and the desulfurizing agent's lifespan is expected to exceed 26 months. The relationship between desulfurization efficiency and operating time in industrial applications is shown in the curve below. Figure 2 As shown, the desulfurizing agent prepared by the present invention has long-term stability.

[0108] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a high-efficiency desulfurizing agent, characterized in that, Includes the following steps: S1. The composite modified biochar, molecular sieve, graphene, pseudo-boehmite binder and deionized water are kneaded evenly and then extruded into strips, and then dried and calcined to obtain the composite carrier. S2. The composite carrier is dispersed in an aqueous ethanol solution, and then an aminosilane coupling agent is added to it. After stirring, the mixture is filtered, washed, and dried to obtain the amino-modified composite carrier. S3. Dissolve nickel salt and copper salt in deionized water, add chelating agent disodium ethylenediaminetetraacetate, stir evenly, then add amino-modified composite carrier, impregnate, and after impregnation is completed, filter, wash and dry to obtain desulfurizing agent precursor; S4. Place the desulfurizing agent precursor in a nitrogen atmosphere, introduce formaldehyde water vapor, reduce it in situ, and then cure it at a constant temperature to obtain the desulfurizing agent. In step S1, the preparation method of the composite modified biochar is as follows: straw powder, cobalt salt and sodium borohydride are added to deionized water, stirred and adsorbed, then filtered, washed and dried, and calcined under a nitrogen atmosphere to obtain composite modified biochar.

2. The production method according to claim 1, characterized by, The mass ratio of straw powder, cobalt salt, and sodium borohydride is 20-40:5-10:10-15.

3. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of the composite modified biochar, molecular sieve, graphene, pseudoboehmite, and deionized water is 25-40:10-15:4-8:15-25:20-30.

4. The method of claim 1, wherein, In step S2, the mass ratio of the composite carrier to the aminosilane coupling agent is 20-40:1-3.

5. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of nickel salt, copper salt, disodium ethylenediaminetetraacetate, and amino-modified composite carrier is 4-8:1-2:5-10:10-15.

6. The method of claim 1, wherein, In step S4, the volume fraction of formaldehyde in the formaldehyde water vapor is 5-10%.

7. The preparation method according to claim 1, characterized in that, In step S4, the in-situ reduction temperature is 180-220℃, and the in-situ reduction time is 3-4 hours.

8. The high-efficiency desulfurizer prepared by the preparation method according to any one of claims 1-7.

9. The application of the high-efficiency desulfurizing agent as described in claim 8 in the desulfurization of heavy naphtha.

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