A high-temperature high-chlorine-content dechlorination agent for syngas refining and a preparation method thereof

Abstract

The present application relates to the technical field of catalyst, and particularly relates to a low-temperature organic sulfur conversion catalyst for synthesis gas and a preparation method thereof.The technical scheme adopted by the present application is: the dechlorination agent comprises an active component and a carrier; the active component is calcium oxide and zinc oxide, and the carrier is gamma-alumina; the content of each component is 30-60 parts by weight of calcium oxide, 10-30 parts by weight of zinc oxide and 20-40 parts by weight of gamma-alumina in terms of oxides based on the total weight of the dechlorination agent; the specific surface area of the gamma-alumina is 150-300 m2 / g, and the pore volume is 0.3-0.6 mL / g; the bulk density of the dechlorination agent is 0.7-0.9 kg / L, and the lateral pressure strength is greater than or equal to 50 N / cm.The present application has the advantages that the breakthrough chlorine capacity and high-temperature stability are improved, the service life of the dechlorination agent is prolonged, the replacement frequency and operation cost are reduced, and the long-period operation requirement of the synthesis gas integrated deep purification system is met.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification and its preparation method. Background Technology

[0002] Syngas (mainly composed of carbon monoxide and hydrogen) is an important intermediate feedstock in coal chemical, natural gas chemical, and oil refining industries, and is widely used in the synthesis of products such as methanol, acetic acid, and ethylene glycol. Hydrogen chloride (HCl) in syngas is a common harmful impurity that can cause irreversible poisoning and deactivation of downstream catalysts, and can also cause corrosion to pipelines and equipment.

[0003] Currently, most industrial dechlorination agents use alkali metal or alkaline earth metal oxides as active components, fixing HCl onto the dechlorination agent through an acid-base reaction. Existing patent literature (such as CN104689785A) discloses a dechlorination agent with calcium oxide, zinc oxide, and aluminum oxide as main components, operating at a temperature range of 5-400℃, suitable for removing hydrogen chloride from raw materials such as syngas, hydrogen, and carbon dioxide. Commercially available products, such as A104 and GR-401, also primarily use calcium oxide and zinc oxide as their main active components.

[0004] However, when the above-mentioned dechlorinating agents are used in syngas refining, their breakthrough chlorine capacity is usually 20-25 wt%. When the chlorine content in the syngas is high (100-2000 ppm), the dechlorinating agent has a short service life, requires frequent replacement, and has high operating costs.

[0005] In addition, process conditions such as reaction temperature and space velocity have a significant impact on the breakthrough chlorine capacity of dechlorinating agents, and there is still room for improvement in the chlorine capacity stability of existing products under high-temperature conditions (250-400℃).

[0006] In summary, existing dechlorinating agents used in syngas refining suffer from low chlorine penetration capacity and insufficient stability under high-temperature conditions, resulting in short service life, frequent replacements, and high operating costs. Therefore, providing a dechlorinating agent with higher chlorine penetration capacity and better high-temperature stability is of great significance for reducing syngas refining costs and ensuring long-term stable operation of downstream catalysts. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification and its preparation method. This dechlorinating agent aims to improve chlorine penetration capacity and high-temperature stability through an optimized combination of active components and a carrier, thereby extending the service life of the dechlorinating agent, reducing replacement frequency and operating costs, and meeting the long-term operation requirements of integrated deep purification systems for syngas. The technical concept of this invention is as follows: using calcium oxide and zinc oxide as composite active components, utilizing the property that calcium and zinc react with hydrogen chloride at high temperatures to generate stable chlorides, thus achieving chlorine fixation; using γ-alumina as a carrier, utilizing its high specific surface area and suitable pore structure to disperse the active components, enhancing the structural stability of the dechlorinating agent. Through a preparation process of kneading, extrusion, drying, and calcination, the active components are uniformly distributed in the carrier and form a stable composite phase, thereby obtaining high chlorine penetration capacity and good stability in the temperature range of 250-400℃. In terms of composition design, the ratio of calcium oxide to zinc oxide is adjusted to balance the adsorption capacity of the dechlorinating agent for hydrogen chloride and the structural strength. In the preparation process, the binding state between the active component and the carrier is optimized by controlling the calcination temperature and time, so as to avoid the decrease in specific surface area due to high-temperature sintering, while ensuring that the active component is fully activated.

[0008] The technical solution of the present invention is as follows: A high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining, characterized in that the dechlorinating agent comprises an active component and a carrier; the active component is calcium oxide and zinc oxide, and the carrier is γ-alumina; based on the total weight of the dechlorinating agent, the content of each component as oxides is: calcium oxide 30-60 parts by weight, zinc oxide 10-30 parts by weight, and γ-alumina 20-40 parts by weight; the specific surface area of ​​the γ-alumina is 150-300 m² / g, and the pore volume is 0.3-0.6 mL / g; the bulk density of the dechlorinating agent is 0.7-0.9 kg / L, and the lateral compressive strength is ≥50 N / cm; the penetration chlorine capacity of the dechlorinating agent at a temperature of 250-400℃ is ≥30 wt%, and the saturated chlorine capacity is ≥40 wt%.

[0009] A method for preparing a high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining, characterized in that, as described in claim 1, the high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining comprises the following steps: (1) mixing calcium source, zinc source, γ-alumina carrier, binder and pore expander evenly, adding deionized water for kneading to obtain a wet material; (2) extruding the wet material obtained in step (1) through an extruder to obtain a molded body; (3) drying the molded body obtained in step (2); and (4) calcining the dried molded body to obtain the dechlorinating agent.

[0010] Furthermore, the calcium source is selected from at least one of calcium carbonate and calcium hydroxide, the zinc source is selected from one or more of zinc oxide, zinc carbonate, and zinc hydroxide, the binder is guar gum powder, and the pore-expanding agent is one or more of polyethylene glycol, polyacrylamide, and carboxymethyl cellulose.

[0011] Furthermore, the die diameter for the extrusion molding is 2-5 mm, and the extrusion pressure is 5-10 MPa.

[0012] Furthermore, the drying temperature is 100-130℃, and the drying time is 4-10 hours.

[0013] Furthermore, the calcination is carried out in an air atmosphere, the calcination temperature is 400-650℃, the calcination time is 3-8 hours, and the heating rate is 1-3℃ / minute.

[0014] A method for using a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification, characterized in that: the high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification according to claim 1 includes the following steps: loading the dechlorinating agent into a fixed-bed reactor, introducing chlorine-containing syngas to be purified, and carrying out a dechlorination reaction under conditions of 250-400℃, atmospheric pressure to 5.0 MPa, and gas hourly space velocity of 500-3000 h⁻¹; the dechlorinating agent does not require reduction activation treatment before the dechlorination reaction and can be used directly; the hydrogen chloride content in the chlorine-containing syngas is 100-2000 ppm, and the chlorine content in the outlet gas is less than 0.1 ppm.

[0015] Furthermore, the dechlorinating agent is suitable for removing hydrogen chloride from the gas phases of syngas, hydrogen, carbon dioxide, and nitrogen, and is used as a protective agent for catalysts in steam reforming, low-temperature shifting, methanation, and methanol synthesis.

[0016] Furthermore, when the chlorine content at the dechlorinating agent bed outlet exceeds the limit, the agent should be replaced or treated offline by switching valves.

[0017] The beneficial effects of this invention are: 1. The dechlorinating agent provided by this invention uses calcium oxide and zinc oxide as composite active components and γ-alumina as a carrier, and is prepared through a process of kneading, extrusion, drying, and calcination. Within a temperature range of 250-400℃, the dechlorinating agent exhibits a penetration chlorine capacity of over 30% and a saturated chlorine capacity of over 40%, effectively extending its service life and reducing replacement frequency and operating costs. The preparation method of the dechlorinating agent is simple, uses widely available raw materials, has low production costs, and is easy to industrialize. This dechlorinating agent is suitable for removing hydrogen chloride from gaseous phases such as syngas, hydrogen, and carbon dioxide, and can be used as a protective agent for catalysts in steam reforming, low-temperature shift conversion, methanation, and methanol synthesis.

[0018] 2. This dechlorinating agent uses calcium oxide and zinc oxide as composite active components and γ-alumina as a carrier. It is prepared through a process of mixing, extrusion, drying, and calcination. It features high chlorine penetration capacity, good high-temperature stability, simple preparation process, and wide availability of raw materials. This dechlorinating agent can be used to remove hydrogen chloride from gaseous phases such as syngas, hydrogen, and carbon dioxide. It can extend the service life of the dechlorinating agent, reduce replacement frequency and operating costs, and is suitable for integrated deep purification systems for syngas. It can also be used as a protective agent for catalysts in steam reforming, low-temperature shift conversion, methanation, and methanol synthesis. Detailed Implementation

[0019] A high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification comprises an active component and a carrier; the active component is calcium oxide and zinc oxide.

[0020] Based on the total weight of the dechlorinating agent, the content of each component, calculated as oxides, is as follows: calcium oxide 30-60 parts by weight, zinc oxide 10-30 parts by weight, and γ-alumina carrier 20-40 parts by weight.

[0021] Preferably, the content of calcium oxide is 40-50 parts by weight, the content of zinc oxide is 15-25 parts by weight, and the content of γ-alumina carrier is 25-35 parts by weight.

[0022] The specific surface area of ​​the γ-alumina support is 150-300 m² / g, and the pore volume is 0.3-0.6 mL / g.

[0023] The present invention also provides a method for preparing the dechlorination agent, comprising the following steps: (1) Raw material mixing: Weigh the calcium source, zinc source and γ-alumina carrier according to the ratio, add the binder and pore expander, and mix evenly; the calcium source is selected from at least one of calcium carbonate and calcium hydroxide, the zinc source is selected from one or more of zinc oxide, zinc carbonate and zinc hydroxide, the binder is guar gum powder, and the pore expander is one or more of polyethylene glycol, polyacrylamide and carboxymethyl cellulose; (2) Kneading and molding: Add deionized water to the mixture obtained in step (1) and knead it to form a plastic wet material; extrude the wet material through an extruder to obtain a strip or cylindrical molded body; (3) Drying: Dry the molded body obtained in step (2) at 100-130℃ for 4-10 hours; (4) Calcination: The dried molded body is heated to 400-650°C in air at a heating rate of 1-3°C / min, and calcined at this temperature for 3-8 hours. After natural cooling, the dechlorination agent is obtained.

[0024] This invention further provides a method for applying the dechlorinating agent, comprising the following steps: loading the dechlorinating agent into a fixed-bed reactor, introducing chlorine-containing synthesis gas to be purified, and carrying out a dechlorination reaction under conditions of 250-400℃, atmospheric pressure to 5.0MPa, and gas hourly space velocity of 500-3000h⁻¹, so that the chlorine content in the outlet gas is less than 0.1ppm. The dechlorinating agent does not require reduction activation treatment before the dechlorination reaction and can be used directly. When the chlorine content at the outlet of the dechlorinating agent bed breaks through, it can be replaced or treated offline by switching valves. The dechlorinating agent is suitable for removing hydrogen chloride from the gas phase of synthesis gas, hydrogen, carbon dioxide, nitrogen, etc., and can be used as a protective agent for catalysts in steam reforming, low-temperature shift reaction, methanation, methanol synthesis, etc.

[0025] This invention aims to provide a high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining. Its core lies in the design of a composite active component of calcium oxide and zinc oxide, combined with a suitable pore structure of the γ-alumina support and a controllable kneading-calcination preparation process. This addresses the problems of low chlorine capacity and insufficient high-temperature stability of existing dechlorinating agents in syngas refining while ensuring dechlorination accuracy. The following examples will specifically illustrate how this goal is achieved.

[0026] 1. Selection and pretreatment of the carrier The support provides a framework for dispersing the active components and ensures the final mechanical strength. In this invention, γ-alumina is preferably used as the support.

[0027] The specific surface area of ​​the γ-alumina support is preferably 150-300 m² / g, and the pore volume is preferably 0.3-0.6 mL / g. This pore structure facilitates the diffusion of reactants and the loading of active components, while the high specific surface area provides ample dispersion sites for the active components. The support can be spherical, strip-shaped, or cylindrical, and its equivalent diameter is preferably 2-5 mm.

[0028] Before use, the carrier can be calcined in an air atmosphere at 350-450℃ for 2-4 hours to remove the moisture and impurities physically adsorbed on the surface of the carrier and stabilize its surface properties.

[0029] 2. Selection of raw materials for active components The active component provides the dechlorinating agent with active centers for chemical reaction with hydrogen chloride. This invention uses calcium oxide and zinc oxide as composite active components. The calcium source is selected from at least one of calcium carbonate and calcium hydroxide, and the zinc source is selected from one or more of zinc oxide, zinc carbonate, and zinc hydroxide.

[0030] The calcium and zinc sources can be dried before use to remove free moisture. Calcium carbonate decomposes at approximately 800-900℃, while calcium hydroxide decomposes into calcium oxide at approximately 500-600℃. During subsequent calcination, these calcium and zinc sources can be converted into active oxide forms.

[0031] The carrier is γ-alumina. Before use, the γ-alumina can be sieved to remove fine powder and obtain particles with uniform size. Depending on the molding requirements, the particle size of the γ-alumina is preferably controlled within the range of 100-300 mesh to facilitate uniform dispersion of the components during subsequent mixing.

[0032] The weighed calcium source, zinc source, and γ-alumina carrier are dry-mixed according to the specified ratio to ensure initial homogeneity. The dry-mixing time should be controlled between 10-30 minutes. After homogeneity, the binder and pore-expanding agent are added and mixing continues to prepare for subsequent kneading and molding. The binder can be selected from guar gum powder, and the pore-expanding agent can be selected from one or more of polyethylene glycol, polyacrylamide, and carboxymethyl cellulose.

[0033] 3. Refined control of the preparation process To achieve uniform distribution and stable binding of active components in the carrier, key steps such as mixing, molding, drying, and calcination need to be controlled.

[0034] The kneading and molding process is a crucial step in determining the uniformity and molding quality of the dechlorinating agent. The dry-mixed raw materials (calcium source, zinc source, γ-alumina carrier, binder, and pore expander) are placed in a kneader, and deionized water is gradually added while stirring. The amount of water added should be controlled to 20-40% of the total mass of the raw materials to achieve a suitable moisture content. The kneading time should be controlled between 20-60 minutes, ideally until all components are fully mixed and the material is in a uniform and plastic state. During the kneading process, the binder absorbs water and swells, which helps to enhance the plasticity of the material and the strength of the molded green body. The pore expander decomposes and volatilizes during the subsequent calcination process, forming a porous structure within the dechlorinating agent, which facilitates the diffusion of reactant gases.

[0035] The uniformly mixed wet material is extruded into shape using an extruder. The die orifice diameter of the extruder can be selected as needed, typically 2-5mm. The extrusion pressure should be controlled evenly to ensure that the extruded strips are dense, smooth, and free of cracks. The extruded strips can be cut into suitable lengths as required, typically 3-15mm.

[0036] The drying process aims to remove free moisture from the shaped body, preventing cracking due to rapid moisture evaporation during subsequent firing. The drying temperature is controlled at 100-130℃, and the drying time is controlled at 4-10 hours. A lower temperature can be used initially during drying, gradually increasing to the set temperature after the moisture has slowly evaporated to reduce the risk of cracking. The dried body should maintain its intact shape, without obvious cracks or deformation.

[0037] The calcination process is a crucial step in converting the calcium and zinc sources into active oxides. The dried green body is placed in a calcination furnace and calcined under a programmed temperature rise in air. The heating rate is controlled at 1-3℃ / min, the calcination temperature at 400-750℃, and the holding time at 3-8 hours. During calcination, calcium carbonate or calcium hydroxide decomposes to form calcium oxide, while the zinc source is converted into zinc oxide, forming a certain interaction with the γ-alumina support. After calcination, the mixture is naturally cooled to room temperature to obtain the finished dechlorination agent.

[0038] In summary, this invention provides a high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining and its preparation method. This dechlorinating agent uses calcium oxide and zinc oxide as composite active components and γ-alumina as a carrier, prepared through a process of kneading, extrusion, drying, and calcination. By optimizing the ratio of active components and the preparation process conditions, the dechlorinating agent achieves a breakthrough chlorine capacity of over 30% and a saturated chlorine capacity of over 40%, exhibiting good high-temperature stability within the 250-400℃ temperature range. This dechlorinating agent is suitable for removing hydrogen chloride from gaseous phases such as syngas, hydrogen, carbon dioxide, and nitrogen. It can be used as a protective agent for catalysts in steam reforming, low-temperature shift conversion, methanation, and methanol synthesis, extending the service life of the dechlorinating agent and reducing replacement frequency and operating costs. The preparation method is simple, uses widely available raw materials, has low production costs, and is easily scalable for industrial production. Example 1

[0039] This embodiment provides a method for preparing a high-temperature, high-chlorine-capacity dechlorinating agent (denoted as dechlorinating agent A) for syngas purification.

[0040] Composition design (by weight of oxides): 40 parts calcium oxide, 20 parts zinc oxide, and 30 parts γ-alumina carrier.

[0041] Preparation process: a. Raw material preparation: Weigh out calcium hydroxide (Ca(OH)2, 40 parts as CaO, purity ≥95%), zinc oxide (ZnO, 20 parts, purity ≥99%), and γ-alumina carrier (30 parts, specific surface area 200m² / g, pore volume 0.45mL / g, particle size 100-200 mesh). Weigh out 3 parts of guar gum powder as binder and 2 parts of polyethylene glycol as pore expander.

[0042] b. Dry mixing: Add calcium hydroxide, zinc oxide, γ-alumina carrier, guar gum powder, and polyethylene glycol to a kneader and dry mix at 200-300 rpm for 15 minutes to ensure that the components are initially mixed evenly.

[0043] c. Kneading and Molding: Gradually add deionized water while stirring, with the amount of water being 30% of the total mass of the raw materials. Continue kneading for 30 minutes to form a uniform and plastic wet material. Extrude the wet material through an extruder with a die diameter of 4mm and an extrusion pressure controlled at 8-10MPa to obtain a strip-shaped wet blank with a diameter of approximately 4mm, which is then cut into lengths of 8-12mm.

[0044] d. Drying: Place the strip-shaped wet blanks in a drying oven and dry them at 110℃ for 6 hours to remove free moisture.

[0045] e. Calcination: The dried green body is placed in a muffle furnace and heated to 550°C at a heating rate of 2°C / min in air atmosphere. It is held at this temperature for 5 hours and then naturally cooled to room temperature to obtain dechlorination agent A. Example 2

[0046] This embodiment provides the preparation of another high-temperature, high-chlorine-capacity dechlorinating agent (denoted as dechlorinating agent B) for syngas purification.

[0047] Composition design (by weight of oxides): 50 parts calcium oxide, 15 parts zinc oxide, and 25 parts γ-alumina carrier.

[0048] Preparation process: a. Raw material preparation: Weigh out calcium hydroxide (Ca(OH)2, 50 parts as CaO, purity ≥95%), zinc oxide (ZnO, 15 parts, purity ≥99%), γ-alumina carrier (25 parts, specific surface area 180m² / g, pore volume 0.40mL / g, particle size 100-200 mesh), and separately weigh out 3 parts of guar gum powder as binder and 2 parts of polyethylene glycol as pore expander.

[0049] b. Dry mixing: Add calcium hydroxide, zinc oxide, γ-alumina carrier, guar gum powder, and polyethylene glycol to a kneader and dry mix at 200-300 rpm for 15 minutes to ensure that the components are initially mixed evenly.

[0050] c. Kneading and Molding: Gradually add deionized water while stirring, with the amount of water being 30% of the total mass of the raw materials. Continue kneading for 30 minutes to form a uniform and plastic wet material. Extrude the wet material through an extruder with a die diameter of 4mm and an extrusion pressure controlled at 8-10MPa to obtain a strip-shaped wet blank with a diameter of approximately 4mm, which is then cut into lengths of 8-12mm.

[0051] d. Drying: Place the strip-shaped wet blanks in a drying oven and dry them at 110℃ for 6 hours to remove free moisture.

[0052] e. Calcination: The dried green body is placed in a muffle furnace and heated to 550°C at a heating rate of 2°C / min in an air atmosphere. It is held at this temperature for 5 hours and then naturally cooled to room temperature to obtain dechlorination agent B. Example 3

[0053] This embodiment provides the preparation of another high-temperature, high-chlorine-capacity dechlorinating agent (denoted as dechlorinating agent C) for syngas purification.

[0054] Composition design (by weight of oxides): 35 parts calcium oxide, 25 parts zinc oxide, and 30 parts γ-alumina carrier.

[0055] Preparation process: a. Raw material preparation: Weigh out calcium hydroxide (Ca(OH)2, 35 parts as CaO, purity ≥95%), zinc oxide (ZnO, 25 parts, purity ≥99%), and γ-alumina carrier (30 parts, specific surface area 220m² / g, pore volume 0.48mL / g, particle size 100-200 mesh). Weigh out 3 parts of guar gum powder as binder and 2 parts of polyethylene glycol as pore expander.

[0056] b. Dry mixing: Add calcium hydroxide, zinc oxide, γ-alumina carrier, guar gum powder, and polyethylene glycol to a kneader and dry mix at 200-300 rpm for 15 minutes to ensure that the components are initially mixed evenly.

[0057] c. Kneading and Molding: Gradually add deionized water while stirring, with the amount of water being 30% of the total mass of the raw materials. Continue kneading for 30 minutes to form a uniform and plastic wet material. Extrude the wet material through an extruder with a die diameter of 4mm and an extrusion pressure controlled at 8-10MPa to obtain a strip-shaped wet blank with a diameter of approximately 4mm, which is then cut into lengths of 8-12mm.

[0058] d. Drying: Place the strip-shaped wet blanks in a drying oven and dry them at 110℃ for 6 hours to remove free moisture.

[0059] e. Calcination: The dried green body is placed in a muffle furnace and heated to 550°C at a heating rate of 2°C / min in an air atmosphere. It is held at this temperature for 5 hours and then naturally cooled to room temperature to obtain dechlorination agent C.

[0060] Example Effect Description The performance of dechlorinating agents A, B, and C prepared in Examples 1 to 3 was evaluated. The evaluation was conducted in a fixed-bed reactor using simulated syngas as the feed gas (composition: H2 40%, CO 50%, N2 10%, HCl 500 ppm). Breakthrough chlorine capacity tests were performed at a reaction temperature of 300°C, a pressure of 1.0 MPa, and a gas hourly space velocity of 2000 h⁻¹. The breakthrough point was defined as an outlet HCl concentration greater than 0.1 ppm, and the breakthrough chlorine capacity was calculated. The lateral pressure strength of the dechlorinating agents was measured using a particle strength tester. Thirty dechlorinating agent particles were randomly selected, and the force values ​​at the time of breakage were recorded and averaged.

[0061] Test results show that dechlorinating agent A has a breakthrough chlorine capacity of 32-35 wt% and a lateral compressive strength of 50-55 N / cm; dechlorinating agent B has a breakthrough chlorine capacity of 35-38 wt% and a lateral compressive strength of 45-50 N / cm; and dechlorinating agent C has a breakthrough chlorine capacity of 28-32 wt% and a lateral compressive strength of 55-60 N / cm. All three dechlorinating agents maintain high chlorine capacity within the temperature range of 250-400℃ and exhibit good structural stability.

[0062] Comparative Example 1 This comparative example provides the preparation of a zinc oxide-free dechlorinating agent (denoted as dechlorinating agent D) to illustrate the synergistic effect of zinc oxide.

[0063] Composition design (by weight of oxides): 60 parts calcium oxide, 30 parts γ-alumina carrier. No zinc oxide added.

[0064] Preparation process: a. Raw material preparation: Weigh out calcium hydroxide (Ca(OH)2, 60 parts as CaO, purity ≥95%), γ-alumina carrier (30 parts, specific surface area 200m² / g, pore volume 0.45mL / g, particle size 100-200 mesh), and separately weigh out 3 parts of guar gum powder as binder and 2 parts of polyethylene glycol as pore expander.

[0065] b. Dry mixing: Add calcium hydroxide, γ-alumina carrier, guar gum powder, and polyethylene glycol to a kneader and dry mix at 200-300 rpm for 15 minutes.

[0066] c. Mixing and molding: Gradually add deionized water while stirring, with the amount of water being 30% of the total mass of the raw materials. Continue mixing and kneading for 30 minutes. Extrude the wet material through an extruder with a die diameter of 4mm and an extrusion pressure controlled at 8-10MPa to obtain a strip-shaped wet blank with a diameter of about 4mm. Cut it to a length of 8-12mm.

[0067] d. Drying: Place the strip-shaped wet blanks in a drying oven and dry them at 110℃ for 6 hours.

[0068] e. Calcination: The dried green body is placed in a muffle furnace and heated to 550°C at a heating rate of 2°C / min in an air atmosphere. It is held at this temperature for 5 hours and then naturally cooled to room temperature to obtain dechlorination agent D.

[0069] Comparative Example 2 This comparative example provides the preparation of a dechlorinating agent (denoted as dechlorinating agent E) that does not contain calcium oxide, to illustrate the main active role of calcium oxide.

[0070] Composition design (by weight of oxides): 50 parts zinc oxide, 40 parts γ-alumina carrier. No calcium oxide added.

[0071] Preparation process: a. Raw material preparation: Weigh zinc oxide (ZnO, 50 parts, purity ≥99%), γ-alumina carrier (40 parts, specific surface area 200m² / g, pore volume 0.45mL / g, particle size 100-200 mesh), and separately weigh 3 parts of guar gum powder as binder and 2 parts of polyethylene glycol as pore expander.

[0072] b. Dry mixing: Add zinc oxide, γ-alumina carrier, guar gum powder, and polyethylene glycol to a kneader and dry mix at 200-300 rpm for 15 minutes.

[0073] c. Mixing and molding: Gradually add deionized water while stirring, with the amount of water being 30% of the total mass of the raw materials. Continue mixing and kneading for 30 minutes. Extrude the wet material through an extruder with a die diameter of 4mm and an extrusion pressure controlled at 8-10MPa to obtain a strip-shaped wet blank with a diameter of about 4mm. Cut it to a length of 8-12mm.

[0074] d. Drying: Place the strip-shaped wet blanks in a drying oven and dry them at 110℃ for 6 hours.

[0075] e. Calcination: The dried green body is placed in a muffle furnace and heated to 550°C at a heating rate of 2°C / min in an air atmosphere. It is held at this temperature for 5 hours and then naturally cooled to room temperature to obtain dechlorination agent E.

[0076] Comparative Example 3 This comparative example provides a dechlorinating agent (denoted as dechlorinating agent F) prepared by a conventional impregnation method to illustrate the effect of different preparation processes on the performance of the dechlorinating agent.

[0077] Composition design (by weight of oxides): 50 parts calcium oxide, 40 parts γ-alumina carrier.

[0078] Preparation process: a. Carrier preparation: Weigh 40 parts of γ-alumina carrier (specific surface area 200m² / g, pore volume 0.45mL / g, spherical particle size 2-4mm), place it in a drying oven and dry at 110℃ for 4 hours.

[0079] b. Preparation of impregnation solution: Weigh calcium hydroxide (50 parts as CaO), add it to deionized water, stir to form a suspension, and control the total volume of the solution to be equivalent to the pore volume of the carrier.

[0080] c. Impregnation: Place the dried γ-alumina support in an impregnation container, spray the impregnation solution evenly onto the surface of the support at room temperature, and let it stand for 2 hours to allow the active components to be fully adsorbed into the pores of the support.

[0081] d. Drying: Place the impregnated material in a drying oven and dry at 110°C for 6 hours.

[0082] e. Calcination: The dried material is placed in a muffle furnace and heated to 550°C at a heating rate of 2°C / min in air atmosphere. The temperature is maintained for 5 hours and then naturally cooled to room temperature to obtain dechlorination agent F.

[0083] Explanation of the comparative effect The dechlorinating agents D, E, and F prepared in Comparative Examples 1 to 3 were evaluated for performance under the same conditions as in the examples. The evaluation was conducted in a fixed-bed reactor using simulated syngas as the feed gas (composition: H2 40%, CO 50%, N2 10%, HCl 500 ppm). Breakthrough chlorine capacity tests were performed at a reaction temperature of 300°C, a pressure of 1.0 MPa, and a gas hourly space velocity of 2000 h⁻¹. The breakthrough point was defined as an outlet HCl concentration greater than 0.1 ppm, and the breakthrough chlorine capacity was calculated. The lateral pressure strength of the dechlorinating agents was measured using a particle strength tester. Thirty dechlorinating agent particles were randomly selected, and the force values ​​at the time of breakage were recorded and averaged.

[0084] Test results show that the breakthrough chlorine capacity of dechlorinating agent D (without zinc oxide) is 22-25 wt%, and the lateral pressure strength is 40-45 N / cm; the breakthrough chlorine capacity of dechlorinating agent E (without calcium oxide) is 12-15 wt%, and the lateral pressure strength is 50-55 N / cm; the breakthrough chlorine capacity of dechlorinating agent F (prepared by impregnation method) is 18-22 wt%, and the lateral pressure strength is 35-40 N / cm.

[0085] Compared with Examples 1 to 3, the breakthrough chlorine capacity of dechlorinator D in Comparative Example 1 was significantly lower than that of the example containing zinc oxide but with the same group ratio, indicating that the addition of zinc oxide has a synergistic effect on improving chlorine capacity; the breakthrough chlorine capacity of dechlorinator E in Comparative Example 2 was significantly lower than that of the example containing calcium oxide, indicating that calcium oxide is the main active component of the dechlorination reaction; the breakthrough chlorine capacity and lateral pressure strength of dechlorinator F in Comparative Example 3 were both lower than those of the example prepared by the kneading method, indicating that the kneading-extrusion-calcination process is more conducive to the uniform compounding of active components and carriers, thereby obtaining higher chlorine capacity and mechanical strength.

[0086] Conclusion: This invention provides a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification and its preparation method. The dechlorinating agent uses calcium oxide and zinc oxide as composite active components and γ-alumina as a carrier, and is prepared through a process of kneading, extrusion, drying, and calcination. By optimizing the ratio of active components and the preparation process conditions, the dechlorinating agent achieves a breakthrough chlorine capacity of over 30% and a saturated chlorine capacity of over 40%, exhibiting good high-temperature stability within the temperature range of 250-400℃.

[0087] This dechlorinating agent is suitable for removing hydrogen chloride from gaseous phases such as syngas, hydrogen, carbon dioxide, and nitrogen. It can be used as a protective agent for catalysts in steam reforming, low-temperature shift reaction, methanation, and methanol synthesis, extending the service life of the dechlorinating agent and reducing replacement frequency and operating costs. The preparation method is simple, uses widely available raw materials, has low production costs, and is easy to scale up for industrial production.

[0088] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements or substitutions without departing from the principles of the present invention, and these improvements or substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining, characterized in that, The dechlorinating agent comprises an active component and a carrier; the active component is calcium oxide and zinc oxide, and the carrier is γ-alumina; based on the total weight of the dechlorinating agent, the content of each component as oxides is: calcium oxide 30-60 parts by weight, zinc oxide 10-30 parts by weight, and γ-alumina 20-40 parts by weight; the specific surface area of ​​the γ-alumina is 150-300 m² / g, and the pore volume is 0.3-0.6 mL / g; the bulk density of the dechlorinating agent is 0.7-0.9 kg / L, and the lateral compressive strength is ≥50 N / cm; the penetration chlorine capacity of the dechlorinating agent at a temperature of 250-400℃ is ≥30 wt%, and the saturated chlorine capacity is ≥40 wt%.

2. A method for preparing a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification, characterized in that, The high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining as described in claim 1 comprises the following steps: (1) mixing calcium source, zinc source, γ-alumina carrier, binder and pore expander evenly, adding deionized water and kneading to obtain a wet material; (2) extruding the wet material obtained in step (1) through an extruder to obtain a molded body; (3) drying the molded body obtained in step (2); and (4) calcining the dried molded body to obtain the dechlorinating agent.

3. The method for preparing a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification according to claim 2, characterized in that: The calcium source is selected from at least one of calcium carbonate and calcium hydroxide, the zinc source is selected from one or more of zinc oxide, zinc carbonate, and zinc hydroxide, the binder is guar gum powder, and the pore-expanding agent is one or more of polyethylene glycol, polyacrylamide, and carboxymethyl cellulose.

4. The method for preparing a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification according to claim 2, characterized in that: The die diameter for extrusion molding is 2-5 mm, and the extrusion pressure is 5-10 MPa.

5. The method for preparing a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification according to claim 2, characterized in that: The drying temperature is 100-130℃, and the drying time is 4-10 hours.

6. The method for preparing a high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification according to claim 2, characterized in that: The calcination is carried out in an air atmosphere at a temperature of 400-650℃ for 3-8 hours, with a heating rate of 1-3℃ / minute.

7. A method for using a high-temperature, high-chlorine-capacity dechlorinating agent in syngas refining, characterized in that: A high-temperature, high-chlorine-capacity dechlorinating agent for syngas purification according to claim 1 comprises the following steps: loading the dechlorinating agent into a fixed-bed reactor, introducing chlorine-containing syngas to be purified, and carrying out a dechlorination reaction under conditions of 250-400℃, atmospheric pressure to 5.0MPa, and gas hourly space velocity of 500-3000h⁻¹; the dechlorinating agent does not require reduction activation treatment before the dechlorination reaction and can be used directly; the hydrogen chloride content in the chlorine-containing syngas is 100-2000ppm, and the chlorine content in the outlet gas is less than 0.1ppm.

8. The method of using a high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining according to claim 7, characterized in that: The dechlorinating agent is suitable for removing hydrogen chloride from the gas phases of synthesis gas, hydrogen, carbon dioxide, and nitrogen, and is used as a protective agent for catalysts in steam reforming, low-temperature shifting, methanation, and methanol synthesis.

9. The method of using a high-temperature, high-chlorine-capacity dechlorinating agent for syngas refining according to claim 7, characterized in that: When the chlorine content at the dechlorinating agent bed outlet exceeds the limit, the agent should be replaced or treated offline by switching valves.