Synthesis gas dechlorination agent and method of making same

Abstract

The present application relates to the technical field of dechlorination agent, in particular to a synthetic gas dechlorination agent and a preparation method thereof, which comprises the following raw materials: gamma-alumina, rare earth composite core-shell particles, ionic liquid-carbonate complex and polyvinyl alcohol.In the present application, the rare earth composite core-shell particles exhibit excellent HCl chemical adsorption and catalytic oxidation activity due to their oxygen-rich core and perovskite shell, can efficiently fix HCl and promote its diffusion to a deeper layer, and the unique core-shell structure effectively delays the "chlorine passivation" effect caused by the formation of a dense surface chloride layer; the ionic liquid-carbonate complex plays a role in precise molecular capture first, and its immobilized structure ensures that the ionic liquid does not flow away, and through the rapid reaction of carbonate and HCl, it realizes initial efficient purification.

Description

Technical Field

[0001] This invention relates to the field of dechlorination agents, and more specifically, to a syngas dechlorination agent and its preparation method. Background Technology

[0002] Syngas (mainly composed of CO and H2) is a key intermediate in coal chemical, natural gas reforming and biomass gasification processes. Its purity directly affects the efficiency and catalyst life of downstream catalytic processes (such as Fischer-Tropsch synthesis, methanol synthesis, etc.). Hydrogen chloride (HCl) is a common trace impurity in syngas, which is extremely harmful. It can not only cause equipment corrosion, but also cause irreversible poisoning and deactivation of downstream precious metal catalysts.

[0003] Given the unique electronic structure and excellent oxygen storage and release capabilities of rare earth elements (such as cerium and lanthanum), they have shown great potential in constructing efficient dechlorination active centers and have become a key direction for the research and development of high-performance dechlorination agents. However, although existing dechlorination agents have initial adsorption activity for HCl, they tend to form a strong and stable chloride layer on their surface after adsorbing HCl. This dense layer covers the remaining active sites, leading to the phenomenon of "chlorine passivation," which prevents the deep activity of the dechlorination agent from being exerted and the chlorine capacity from being far lower than the theoretical value. In view of this, we propose a syngas dechlorination agent and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a syngas dechlorination agent and its preparation method, in order to solve the problem mentioned in the background art that although existing dechlorination agents have initial adsorption activity for HCl, they easily form a strong and stable chloride layer on their surface after adsorbing HCl. This dense layer will cover the remaining active sites, resulting in "chlorine passivation" phenomenon, which causes the deep activity of the dechlorination agent to be unable to be exerted and the chlorine capacity to be far lower than the theoretical value.

[0005] This invention provides a syngas dechlorination agent, comprising the following raw materials: γ-alumina, rare earth composite core-shell particles, ionic liquid-carbonate complex, and polyvinyl alcohol;

[0006] Rare earth composite core-shell particles are formed by reducing nano-cerium oxide with hydrogen to form an oxygen-rich vacancy core, and then depositing and calcining lanthanum-manganese precursor on its surface to obtain a coated lanthanum manganate shell.

[0007] The ionic liquid-carbonate composite is formed by silanizing the surface of SBA-15 with 3-chloropropyltrimethoxysilane and grafting N-methylimidazolium, followed by impregnation with carbonate and drying to form an immobilized ionic liquid-carbonate composite.

[0008] Preferably, the composition comprises 5-10 parts by weight of γ-alumina, 15-35 parts by weight of rare earth composite core-shell particles, 15-30 parts by weight of ionic liquid-carbonate composite, and 1-3 parts by weight of polyvinyl alcohol.

[0009] As a preferred embodiment, the rare earth composite core-shell particles are prepared as follows:

[0010] Nano-cerium oxide was placed in a tube furnace and first purged with nitrogen for 30 minutes. Then it was treated with hydrogen gas at 350-450℃ with a volume concentration of 5-10% for 1-3 hours. After treatment, the nitrogen gas was used to replace the cerium oxide core and the core was removed to obtain the cerium oxide core.

[0011] Citric acid was added to a mixed metal nitric acid solution, with a total molar ratio of citric acid to metal ions of 1:1. The pH was adjusted to 5-6 with 0.1 mol / L ammonia water, and the solution was stirred at 200-300 rpm to obtain a lanthanum-manganese precursor solution.

[0012] The cerium oxide cores are ultrasonically dispersed in deionized water at a solid-liquid ratio of 1:20-50 with a power of 100-200W to form a cerium oxide suspension.

[0013] The lanthanum-manganese precursor solution was added dropwise to the cerium oxide suspension under stirring at 300-400 rpm for 20-60 min. After the addition was completed, stirring was continued for 1-2 h, and the mixture was concentrated by evaporation at 60-80 °C under normal pressure. Then it was dried at 80-100 °C for 12 h to obtain the dry powder coated with the precursor.

[0014] The dry powder is placed in a tube furnace, purged with nitrogen for 30 minutes, and then heated to 500-550℃ at a rate of 2-5℃ / min. The temperature is then maintained for 2-4 hours. The powder is cooled to room temperature to obtain rare earth composite core-shell particles.

[0015] Preferably, the mixed metal nitric acid solution comprises a 0.2-0.5 mol / L lanthanum nitrate solution and a 0.2-0.5 mol / L manganese nitrate solution, wherein the molar ratio of lanthanum to manganese is 1:1.

[0016] Preferably, the mass ratio of the lanthanum-manganese precursor solution to the cerium oxide core is 0.05-0.20:1.

[0017] As a preferred embodiment, the preparation method of the ionic liquid-carbonate complex is as follows:

[0018] Dry SBA-15 was added to anhydrous toluene at a solid-liquid ratio of 1:20 and ultrasonically dispersed at 100-200W for 5-10 min. Then, 12-15% of 3-chloropropyltrimethoxysilane by mass of SBA-15 was added, and the mixture was stirred at 200-300 rpm for 12 h at 80-90 °C under nitrogen protection. After the reaction, the mixture was cooled to room temperature, washed three times with anhydrous ethanol, filtered, and dried under nitrogen. The mixture was then vacuum dried at 80 °C for 2 h to obtain the support-Cl.

[0019] The carrier-Cl was dispersed in anhydrous methanol at a solid-liquid ratio of 1:10 and sonicated at 100-200W for 5 min. N-methylimidazolium with a molar ratio of 3:1 to 3-chloropropyltrimethoxysilane was added, and the mixture was stirred at 300-400 rpm for 12-18 h at 50-65 °C under nitrogen protection. After the reaction was completed, the mixture was washed 3-5 times alternately with acetonitrile and ethanol, and then dried under vacuum at 60 °C for 6 h to obtain the surface-immobilized ionic liquid-Cl.

[0020] The surface-immobilized ionic liquid -Cl was dispersed in deionized water at a solid-liquid ratio of 1:5-10, and 0.5-1.0 mol / L potassium carbonate solution was added. The mixture was stirred at 300-400 rpm for 30-60 min, and then evaporated and concentrated. Under nitrogen atmosphere, it was dried at 120 °C for 2 h, and then the temperature was slowly increased to 150-180 °C and held at this temperature for 2-4 h. After cooling, the ionic liquid-carbonate complex was obtained.

[0021] Preferably, the molar ratio of carbonate ions in the potassium carbonate to the surface-immobilized ionic liquid -Cl is 0.5-2.0:1.

[0022] On the other hand, the present invention provides a method for preparing a syngas dechlorination agent, which includes the following steps:

[0023] S1.1 Weigh the following raw materials in parts by weight: 5-10 parts by weight of γ-alumina, 15-35 parts by weight of rare earth composite core-shell particles, 15-30 parts by weight of ionic liquid-carbonate composite, and 1-3 parts by weight of polyvinyl alcohol.

[0024] S1.2. Place the γ-alumina, rare earth composite core-shell particles, and ionic liquid-carbonate composite into a mixer and dry mix at 100-200 rpm for 10-15 min;

[0025] Then add polyvinyl alcohol solution and knead at 200-300 rpm for 15-30 minutes to form a plastic wet material;

[0026] S1.3. The wet material is extruded and granulated to obtain wet granules; then pre-drying at 50-60℃ for 2 hours, and then curing and drying at 100-120℃ for 4-6 hours to obtain the syngas dechlorination agent.

[0027] Preferably, in step S1.2, the polyvinyl alcohol solution is obtained by adding polyvinyl alcohol to deionized water at a mass ratio of 1:10 and stirring at 300-400 rpm for 1-2 hours at 90°C.

[0028] Preferably, in step S1.3, the diameter of the wet granules is 2-4 mm; and the pressure of the extrusion granulator is 5-10 MPa.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] In this invention, a syngas dechlorination agent and its preparation method are disclosed. The rare earth composite core-shell particles, with their oxygen-rich vacancy core and perovskite shell, exhibit excellent HCl chemical adsorption and catalytic oxidation activity. They can efficiently fix HCl and promote its diffusion to deeper layers. Their unique core-shell structure effectively delays the "chlorine passivation" effect caused by the dense chloride layer on the surface. The ionic liquid-carbonate complex plays a leading role in precise molecular-level capture. Its immobilized structure ensures that the ionic liquid is not lost, and it achieves efficient initial purification through the rapid reaction of carbonate and HCl. The ionic liquid complex effectively reduces the risk of direct impact and shielding of rare earth active sites by low-temperature HCl at the front end, while the rare earth core-shell particles ensure high overall chlorine capacity and long-term stability at the rear. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a syngas dechlorination agent, comprising the following raw materials: γ-alumina, rare earth composite core-shell particles, ionic liquid-carbonate complex, and polyvinyl alcohol;

[0033] Rare earth composite core-shell particles are formed by reducing nano-cerium oxide with hydrogen to form an oxygen-rich vacancy core, and then depositing and calcining lanthanum-manganese precursor on its surface to obtain a coated lanthanum manganate shell.

[0034] The ionic liquid-carbonate composite is formed by silanizing the surface of SBA-15 with 3-chloropropyltrimethoxysilane and grafting N-methylimidazolium, followed by impregnation with carbonate and drying to form an immobilized ionic liquid-carbonate composite.

[0035] γ-alumina (purity ≥99.0%, CAS No.: 68389-42-4) was purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd.

[0036] Nano-cerium oxide (99.5% purity) was purchased from Shanghai Myriel Biochemical Technology Co., Ltd.

[0037] Lanthanum nitrate (CAS No. 100587-94-8, purity 99.99%) was purchased from Jining Maikerui Rare Earth Co., Ltd.

[0038] Manganese nitrate (CAS No. 10377-66-9, 50% purity solution) was purchased from Shanxi Wencheng Chemical Co., Ltd.

[0039] SBA-15 (CAS No. 14639-89-5) Shanghai Jingkang Bioengineering Co., Ltd.

[0040] 3-Chloropropyltrimethoxysilane (CAS No. 2530-87-2, purity 99%) was purchased from Hubei Chenghai Chemical Co., Ltd.

[0041] N-Methylimidazole (CAS No. 616-47-7, purity 99%) was purchased from Sichuan Hainuowei Technology Co., Ltd.

[0042] Polyvinyl alcohol (CAS No. 9002-89-5) was purchased from Sichuan Laitejuxin Pharmaceutical Excipients Co., Ltd.

[0043] The dried SBA-15 is prepared by pre-drying SBA-15 under vacuum at 120°C for 6 hours.

[0044] The polyvinyl alcohol solution is obtained by adding polyvinyl alcohol to deionized water at a mass ratio of 1:10 and stirring at 400 rpm for 2 hours at 90°C.

[0045] Example 1: A method for preparing a syngas dechlorination agent, comprising the following steps:

[0046] S1.1 Weigh the following raw materials in parts by weight: 5 parts by weight of γ-alumina, 15 parts by weight of rare earth composite core-shell particles, 15 parts by weight of ionic liquid-carbonate composite, and 1 part by weight of polyvinyl alcohol.

[0047] S1.2, Place the γ-alumina, rare earth composite core-shell particles, and ionic liquid-carbonate composite into a mixer and dry mix at 100 rpm for 15 min;

[0048] Then add polyvinyl alcohol solution and knead at 200 rpm for 15 minutes to form a plastic wet material;

[0049] S1.3. The wet material is extruded through a granulator (pressure 5MPa) to obtain wet granules with a diameter of 2mm; then pre-drying at 50℃ for 2h, and then curing and drying at 100℃ for 6h to obtain a syngas dechlorination agent.

[0050] The preparation method of rare earth composite core-shell particles is as follows:

[0051] Nano-cerium oxide was placed in a tube furnace and first purged with nitrogen for 30 minutes. Then it was treated with 5% hydrogen at 350°C for 3 hours. After treatment, it was replaced with nitrogen to return to room temperature and removed to obtain the cerium oxide core.

[0052] A 0.2 mol / L lanthanum nitrate solution and a 0.2 mol / L manganese nitrate solution were mixed, with a molar ratio of lanthanum to manganese of 1:1, to obtain a mixed metal nitric acid solution. Citric acid was added to the mixed metal nitric acid solution, with a total molar ratio of citric acid to metal ions of 1:1. The pH was adjusted to 5 with 0.1 mol / L ammonia water, and the solution was stirred at 300 rpm to obtain a lanthanum-manganese precursor solution.

[0053] The cerium oxide cores were ultrasonically dispersed in deionized water at a solid-liquid ratio of 1:20 using a power of 100W to form a cerium oxide suspension.

[0054] The lanthanum-manganese precursor solution was added dropwise to the cerium oxide suspension (mass ratio 0.05:1) under stirring at 300 rpm for 30 min. After the addition was completed, stirring was continued for 1 h, and the solution was concentrated by evaporation at 60 °C under normal pressure. Then it was dried at 80 °C for 12 h to obtain the dry powder coated with the precursor.

[0055] The dry powder was placed in a tube furnace and purged with nitrogen for 30 minutes. The temperature was then increased to 500°C at a rate of 2°C / min and held for 2 hours. The powder was then cooled to room temperature to obtain rare earth composite core-shell particles.

[0056] The preparation method of ionic liquid-carbonate complex is as follows:

[0057] Dry SBA-15 was added to anhydrous toluene at a solid-liquid ratio of 1:20 and ultrasonically dispersed at 100W for 5 min. Then, 3-chloropropyltrimethoxysilane (12% by mass of SBA-15) was added, and the mixture was stirred at 200 rpm at 80 °C for 12 h under nitrogen protection. After the reaction, the mixture was cooled to room temperature, washed three times with anhydrous ethanol, filtered, and dried under nitrogen. The mixture was then vacuum dried at 80 °C for 2 h to obtain the support-Cl.

[0058] The carrier-Cl was dispersed in anhydrous methanol at a solid-liquid ratio of 1:10 and sonicated at 100W for 5 min. N-methylimidazolium with a molar ratio of 3:1 to 3-chloropropyltrimethoxysilane was added, and the mixture was stirred at 300 rpm for 12 h at 60 °C under nitrogen protection. After the reaction was completed, the mixture was washed three times alternately with acetonitrile and ethanol, and then dried under vacuum at 60 °C for 6 h to obtain the surface-immobilized ionic liquid-Cl.

[0059] The surface-immobilized ionic liquid -Cl was dispersed in deionized water at a solid-liquid ratio of 1:5, and a 0.5 mol / L potassium carbonate solution was added, wherein the molar ratio of carbonate ions in potassium carbonate to surface-immobilized ionic liquid -Cl was 0.5:1. The mixture was stirred at 300 rpm for 30 min, and then evaporated and concentrated. Under nitrogen atmosphere, it was dried at 120 °C for 2 h, and then kept at 150 °C for 2 h. After cooling, the ionic liquid-carbonate complex was obtained.

[0060] Example 2: The difference between this example and Example 1 is that the volume concentration of hydrogen is 8%.

[0061] Example 3: The difference between this example and Example 1 is that the volume concentration of hydrogen is 10%.

[0062] Example 4: The difference between this example and Example 1 is that the mass ratio of the lanthanum-manganese precursor solution to the cerium oxide core is 0.12:1.

[0063] Example 5: The difference between this example and Example 1 is that the mass ratio of the lanthanum-manganese precursor solution to the cerium oxide core is 0.20:1.

[0064] Determination of static chlorine adsorption capacity: Accurately weigh a certain mass (e.g., 0.5 g) of rare earth composite core-shell particle sample and place it in a quartz reaction tube. Under an inert gas atmosphere (e.g., nitrogen), raise the temperature to its optimal operating temperature (e.g., 300 °C) and purge for 1 hour to clean the surface. Cool the system to the predetermined test temperature (e.g., 250 °C) and introduce a standard HCl gas of known concentration (e.g., 1000 ppm) carried by an inert gas, controlling a constant space velocity. Use a downstream ion chromatograph to detect the HCl concentration in the outlet gas in real time. When the outlet concentration reaches 5% of the inlet concentration (i.e., the breakthrough point), stop the gas flow. Calculate the total amount of HCl adsorbed from the start to the breakthrough point by integration, and divide by the sample mass to obtain the static chlorine adsorption capacity.

[0065] Determination of resistance to chlorine passivation (dynamic chlorine capacity retention): Similar to the static chlorine adsorption capacity test described above, proceed to the breakthrough point and record the amount of chlorine adsorbed (denoted as C1). Without changing the sample, switch to an inert gas and heat to a higher temperature (e.g., 500°C), purge for a period of time to desorb physically adsorbed and partially weakly chemically adsorbed chlorine-containing species, and remove Cl... - Deep oxidation to release Cl2; cool the system to the same temperature as the initial adsorption, and then pass HCl standard gas under the same conditions again for a second adsorption test until breakthrough occurs again. Record the amount of chlorine adsorbed this time (denoted as C2); calculate the dynamic chlorine capacity retention rate (%) = (C2 / C1) × 100%.

[0066] Specific surface area determination: Accurately weigh a small amount of sample (e.g., 0.1 g), and degas it for several hours under vacuum or high-purity N2 gas flow at 200-300℃ to thoroughly remove adsorbed moisture and impurities from the surface; use a specific surface area and pore size analyzer to perform nitrogen adsorption-desorption isotherm tests at liquid nitrogen temperature (-196℃); calculate the specific surface area (m²) using the BET model. 2 / g).

[0067] Table 1 Performance data of rare earth composite core-shell particles

[0068] Static chlorine adsorption capacity Dynamic chlorine retention rate Specific surface area Example 1 <![CDATA[78.5mg Cl - / g]]> 72% <![CDATA[95m 2 / g]]> Example 2 <![CDATA[92.3mg Cl - / g]]> 85% <![CDATA[88m 2 / g]]> Example 3 <![CDATA[89.6mg Cl - / g]]> 81% <![CDATA[75m 2 / g]]> Example 4 <![CDATA[108.7mg Cl - / g]]> 89% <![CDATA[68m 2 / g]]> Example 5 <![CDATA[125.2mg Cl - / g]]> 76% <![CDATA[52m 2 / g]]>

[0069] Comparing Examples 1, 2, and 3, it can be seen that when the shell thickness is fixed, increasing the hydrogen concentration from 5% to 8% significantly improves both the static chlorine adsorption capacity and the dynamic chlorine capacity retention rate. This indicates that moderate reduction treatment creates more oxygen vacancies, enhancing the core's ability to activate and transfer chlorine species.

[0070] When the concentration was further increased to 10% (Example 3), the specific surface area decreased significantly due to slight sintering, resulting in a decline in both the static chlorine adsorption capacity and the dynamic chlorine capacity retention rate.

[0071] Comparing Examples 1, 4, and 5, it can be seen that increasing the proportion of the precursor directly increases the loading of the active component, thus significantly improving the static chlorine adsorption capacity.

[0072] In Example 1, the protection was insufficient, resulting in a low dynamic chlorine capacity retention rate; Example 4 showed better protection, maintaining excellent stability under high chlorine capacity (retention rate of 89%).

[0073] Although Example 5 showed the highest static chlorine adsorption capacity, it blocked some of the core pores, hindering the internal diffusion of HCl molecules and the desorption of products, resulting in a sharp decrease in specific surface area and a further reduction in dynamic chlorine capacity retention.

[0074] Example 6: A method for preparing a syngas dechlorination agent, comprising the following steps:

[0075] S1.1 Weigh the following raw materials in parts by weight: 10 parts by weight of γ-alumina, 35 parts by weight of rare earth composite core-shell particles, 30 parts by weight of ionic liquid-carbonate composite, and 3 parts by weight of polyvinyl alcohol.

[0076] S1.2. Place the γ-alumina, rare earth composite core-shell particles, and ionic liquid-carbonate composite into a mixer and dry mix at 200 rpm for 15 min;

[0077] Then add polyvinyl alcohol solution and knead at 300 rpm for 30 minutes to form a plastic wet material;

[0078] S1.3. The wet material is extruded and granulated to obtain wet granules with a diameter of 2-4 mm; then pre-dried at 60℃ for 2 h, and then cured and dried at 120℃ for 6 h to obtain the syngas dechlorination agent.

[0079] The preparation method of rare earth composite core-shell particles is as follows:

[0080] Nano-cerium oxide was placed in a tube furnace and first purged with nitrogen for 30 minutes. Then it was treated with 5% hydrogen at 450°C for 3 hours. After treatment, it was replaced with nitrogen to return to room temperature and removed to obtain the cerium oxide core.

[0081] A 0.5 mol / L lanthanum nitrate solution and a 0.5 mol / L manganese nitrate solution were mixed, with a molar ratio of lanthanum to manganese of 1:1, to obtain a mixed metal nitric acid solution. Citric acid was added to the mixed metal nitric acid solution, with a total molar ratio of citric acid to metal ions of 1:1. The pH was adjusted to 6 with 0.1 mol / L ammonia water, and the solution was stirred at 300 rpm to obtain a lanthanum-manganese precursor solution.

[0082] The cerium oxide cores were ultrasonically dispersed in deionized water at a solid-liquid ratio of 1:50 using a power of 200W to form a cerium oxide suspension.

[0083] The lanthanum-manganese precursor solution was added dropwise to the cerium oxide suspension (mass ratio 0.12:1) under stirring at 400 rpm for 60 min. After the addition was completed, stirring was continued for 2 h, and the solution was concentrated by evaporation at 80 °C under normal pressure. Then, it was dried at 100 °C for 12 h to obtain the dry powder coated with the precursor.

[0084] The dry powder was placed in a tube furnace and purged with nitrogen for 30 minutes. The temperature was then increased to 550°C at a rate of 5°C / min and held for 4 hours. The powder was then cooled to room temperature to obtain rare earth composite core-shell particles.

[0085] The preparation method of ionic liquid-carbonate complex is as follows:

[0086] Dry SBA-15 was added to anhydrous toluene at a solid-liquid ratio of 1:20 and ultrasonically dispersed at 200W for 10 min. Then, 15% of 3-chloropropyltrimethoxysilane by mass of SBA-15 was added, and the mixture was stirred at 300 rpm at 90 °C for 12 h under nitrogen protection. After the reaction, the mixture was cooled to room temperature, washed three times with anhydrous ethanol, filtered, and dried under nitrogen. The mixture was then vacuum dried at 80 °C for 2 h to obtain the support-Cl.

[0087] The carrier-Cl was dispersed in anhydrous methanol at a solid-liquid ratio of 1:10 and sonicated at 200W for 5 min. N-methylimidazolium with a molar ratio of 3:1 to 3-chloropropyltrimethoxysilane was added, and the mixture was stirred at 400 rpm at 60 °C for 18 h under nitrogen protection. After the reaction was completed, the mixture was washed 5 times alternately with acetonitrile and ethanol, and then dried under vacuum at 60 °C for 6 h to obtain the surface-immobilized ionic liquid-Cl.

[0088] The surface-immobilized ionic liquid -Cl was dispersed in deionized water at a solid-liquid ratio of 1:10, and a 1.0 mol / L potassium carbonate solution was added, wherein the molar ratio of carbonate ions in potassium carbonate to surface-immobilized ionic liquid -Cl was 0.5:1. The mixture was stirred at 400 rpm for 60 min, and then evaporated and concentrated. Under nitrogen atmosphere, it was dried at 120 °C for 2 h, and then kept at 180 °C for 3 h. After cooling, the ionic liquid-carbonate complex was obtained.

[0089] Example 7: The difference between this example and Example 6 is that the molar ratio of carbonate ions in potassium carbonate to surface-immobilized ionic liquid -Cl is 1.0:1.

[0090] Example 8: The difference between this example and Example 6 is that the molar ratio of carbonate ions in potassium carbonate to surface-immobilized ionic liquid -Cl is 2.0:1.

[0091] Determination of ion exchange capacity: Accurately weigh 0.1-0.2 g of dried complex sample and place it in an Erlenmeyer flask; add excess standard hydrochloric acid solution of known concentration (e.g., 0.1 mol / L, 20.00 mL), and stir magnetically for 2-4 hours to ensure that carbonate and H+ ions in the complex are in equilibrium. + Complete the reaction; filter the solution, wash the solid thoroughly with deionized water, and combine the filtrate and washings; back-titrate the excess hydrochloric acid with a standard sodium hydroxide solution (e.g., 0.1 mol / L) using methyl orange-bromocresol green as an indicator; calculate the number of moles of basic groups per unit mass of sample based on the amount of hydrochloric acid consumed.

[0092] Determination of low-temperature breakthrough chlorine capacity: A certain volume (e.g., 1 mL) of composite particles is packed into a fixed-bed reaction tube and activated by purging at 120 °C for 1 hour under an inert gas (e.g., nitrogen); the system is cooled to a low temperature (e.g., 80-120 °C), and a simulated synthesis gas containing a certain concentration of HCl (e.g., 100 ppm) is introduced while maintaining a constant space velocity; the concentration of HCl in the reactor outlet gas is monitored in real time using an online hydrogen ion flame detector, and the time from the start to the outlet concentration reaching 5% of the inlet concentration (breakthrough point) is recorded; a concentration-time curve (breakthrough curve) is plotted, and the breakthrough chlorine capacity (the amount of adsorption at the breakthrough point) is calculated.

[0093] Determination of thermal stability (component retention): Accurately weigh a certain mass (m1) of the composite sample, place it in a muffle furnace, and under a nitrogen atmosphere, program the temperature to a set temperature (e.g., 250℃, higher than its working temperature but lower than the preparation and curing temperature), and maintain the temperature for 2 hours; after cooling, immediately remove it and accurately weigh its mass (m2); component retention (%) = (m2 / m1) × 100%.

[0094] Table 2 Performance data of ionic liquid-carbonate complexes

[0095] Ion exchange capacity Low temperature penetration chlorine capacity Thermal stability (component retention rate) Example 6 <![CDATA[0.85mmol OH - / g]]> 24.5mg / g 98.5% Example 7 <![CDATA[1.58mmol OH - / g]]> 45.8mg / g 97.2% Example 8 <![CDATA[1.62mmol OH - / g]]> 47.1 mg / g 94.0%

[0096] In Example 6 (molar ratio 0.5:1), the ionic liquid failed to completely transform from the Cl type to the more active carbonate type, resulting in a large number of chloride ions still occupying sites; therefore, its ion exchange capacity (0.85 mmol / g) was much lower than that of Examples 7 and 8.

[0097] Example 7 (molar ratio 1.0:1) achieved maximum ion exchange, with the density of basic sites reaching a peak (1.58 mmol / g).

[0098] Example 8 (molar ratio 2.0:1) showed only a slight increase in capacity (1.62 mmol / g). This slight increase did not come from more surface sites, but from the introduction of free potassium carbonate. These free salts were physically adsorbed or deposited in the pores and also contributed a small amount of alkalinity.

[0099] Example 6 had the lowest chlorine penetration capacity (24.5 mg / g) due to insufficient active sites; Examples 7 and 8, due to their high density of basic sites, exhibited significantly higher chlorine penetration capacities (approximately 46-47 mg / g), meaning that more HCl gas could be processed before penetration.

[0100] Example 6 contains a large amount of stable Cl - Ions have the highest thermal stability (98.5%), but this comes at the cost of reduced activity.

[0101] Example 7 achieved high activity while maintaining excellent stability (97.2%), demonstrating that the surface-immobilized ionic liquid-carbonate structure itself is stable.

[0102] The stability of Example 8 showed a significant decrease (94.0%), possibly because excess potassium carbonate existed in the pores as physical adsorption or microcrystals, without forming a strong chemical bond with the support. Under the test conditions of 250°C, this free carbonate may have slightly decomposed or caused structural changes, resulting in mass loss. In actual operation, this loss of active components can lead to performance degradation and downstream contamination.

[0103] Example 9: A method for preparing a syngas dechlorination agent, comprising the following steps:

[0104] S1.1 Weigh the following raw materials in parts by weight: 8 parts by weight of γ-alumina, 25 parts by weight of rare earth composite core-shell particles, 22 parts by weight of ionic liquid-carbonate composite, and 2 parts by weight of polyvinyl alcohol.

[0105] S1.2. Place the γ-alumina, rare earth composite core-shell particles, and ionic liquid-carbonate composite into a mixer and dry mix at 200 rpm for 15 min;

[0106] Then add polyvinyl alcohol solution and knead at 300 rpm for 30 minutes to form a plastic wet material;

[0107] S1.3. The wet material is extruded and granulated to obtain wet granules with a diameter of 2-4 mm; then pre-dried at 60℃ for 2 h, and then cured and dried at 120℃ for 6 h to obtain the syngas dechlorination agent.

[0108] The preparation method of rare earth composite core-shell particles is as follows:

[0109] Nano-cerium oxide was placed in a tube furnace and first purged with nitrogen for 30 minutes. Then it was treated with 5% hydrogen at 450°C for 3 hours. After treatment, it was replaced with nitrogen to return to room temperature and removed to obtain the cerium oxide core.

[0110] A 0.5 mol / L lanthanum nitrate solution and a 0.5 mol / L manganese nitrate solution were mixed, with a molar ratio of lanthanum to manganese of 1:1, to obtain a mixed metal nitric acid solution. Citric acid was added to the mixed metal nitric acid solution, with a total molar ratio of citric acid to metal ions of 1:1. The pH was adjusted to 6 with 0.1 mol / L ammonia water, and the solution was stirred at 300 rpm to obtain a lanthanum-manganese precursor solution.

[0111] The cerium oxide cores were ultrasonically dispersed in deionized water at a solid-liquid ratio of 1:40 using a power of 200W to form a cerium oxide suspension.

[0112] The lanthanum-manganese precursor solution was added dropwise to the cerium oxide suspension (mass ratio 0.12:1) under stirring at 400 rpm for 60 min. After the addition was completed, stirring was continued for 2 h, and the solution was concentrated by evaporation at 60 °C under normal pressure. Then it was dried at 80 °C for 12 h to obtain the dry powder coated with the precursor.

[0113] The dry powder was placed in a tube furnace and purged with nitrogen for 30 minutes. The temperature was then increased to 500°C at a rate of 3°C / min and held for 4 hours. The powder was then cooled to room temperature to obtain rare earth composite core-shell particles.

[0114] The preparation method of ionic liquid-carbonate complex is as follows:

[0115] Dry SBA-15 was added to anhydrous toluene at a solid-liquid ratio of 1:20 and ultrasonically dispersed at 200W for 10 min. Then, 3-chloropropyltrimethoxysilane (14% by mass of SBA-15) was added, and the mixture was stirred at 300 rpm at 80 °C for 12 h under nitrogen protection. After the reaction, the mixture was cooled to room temperature, washed three times with anhydrous ethanol, filtered, and dried under nitrogen. The mixture was then vacuum dried at 80 °C for 2 h to obtain the support-Cl.

[0116] The carrier-Cl was dispersed in anhydrous methanol at a solid-liquid ratio of 1:10 and sonicated at 200W for 5 min. N-methylimidazolium with a molar ratio of 3:1 to 3-chloropropyltrimethoxysilane was added, and the mixture was stirred at 400 rpm at 60 °C for 12 h under nitrogen protection. After the reaction was completed, the mixture was washed 5 times alternately with acetonitrile and ethanol, and then dried under vacuum at 60 °C for 6 h to obtain the surface-immobilized ionic liquid-Cl.

[0117] The surface-immobilized ionic liquid -Cl was dispersed in deionized water at a solid-liquid ratio of 1:8, and a 0.5 mol / L potassium carbonate solution was added, wherein the molar ratio of carbonate ions in potassium carbonate to surface-immobilized ionic liquid -Cl was 1.0:1. The mixture was stirred at 400 rpm for 60 min, and then evaporated and concentrated. Under nitrogen atmosphere, it was dried at 120 °C for 2 h, and then kept at 160 °C for 3 h. After cooling, the ionic liquid-carbonate complex was obtained.

[0118] Example 10: The difference between this example and Example 9 is that 15 parts by weight of rare earth composite core-shell particles are used.

[0119] Example 11: The difference between this example and Example 9 is that 35 parts by weight of rare earth composite core-shell particles are used.

[0120] Example 12: The difference between this example and Example 9 is that 15 parts by weight of ionic liquid-carbonate complex are used.

[0121] Example 13: The difference between this example and Example 9 is that 30 parts by weight of ionic liquid-carbonate complex are used.

[0122] Determination of lateral pressure crushing strength: Randomly select at least 30 complete and regularly shaped dechlorinating agent particles; using a particle strength tester, place a single particle horizontally between two plates and apply pressure at a constant rate until the particle breaks; record the force (in Newtons, N) that the particle experiences when it breaks.

[0123] Determination of breakthrough chlorine capacity: A certain volume (e.g., 5 mL) of dechlorinating agent granules is packed into a fixed-bed reactor. Under a nitrogen atmosphere, the temperature is programmed to a predetermined temperature (e.g., 200 °C) and activated by purging for 1 hour. The temperature is then adjusted to the test point (e.g., 120 °C for low temperature, 250 °C for medium temperature). Simulated synthesis gas (containing H2, CO, CO2, N2, etc.) containing a specific concentration of HCl (e.g., 100 ppm) is introduced while maintaining a constant space velocity. The concentration of HCl in the reactor outlet gas is monitored in real time using an online hydrogen ion flame detector. An outlet HCl concentration-time curve (breakthrough curve) is plotted. The breakthrough time (the time when the outlet concentration reaches 1% or 5% of the inlet concentration) and the saturation time (the time when the outlet concentration reaches 95% of the inlet concentration) are recorded. The breakthrough chlorine capacity at 120 °C and 250 °C is calculated by integration.

[0124] Wear rate determination: In the chlorine penetration capacity test device, when clean inert gas is introduced, the pressure difference before and after the gas passes through the dechlorinating agent bed is measured using a differential pressure gauge; a certain mass (m0) of dechlorinating agent sample is weighed and placed in a standard wear test device (such as a Ro-Tap vibrating sieve or a specific wear drum); after running for a specified time (such as 30 minutes), it is sieved with a sieve of a specific mesh size (such as 20 mesh), and the mass (m1) of the unwearied particles is collected and weighed; the wear rate (%) is calculated as [(m0-m1) / m0]×100%.

[0125] Table 3 Performance data of syngas dechlorination agent

[0126] Lateral crushing strength Chlorine penetration tolerance (120℃) Chlorine penetration tolerance (250℃) Wear rate Example 9 48N 42.5mg / g 98.2 mg / g 0.8% Example 10 52N 43.1 mg / g 72.5mg / g 0.7% Example 11 41N 41.8 mg / g 115.6 mg / g 1.2% Example 12 51N 31.2 mg / g 99.5mg / g 0.9% Example 13 45N 48.9 mg / g 96.0 mg / g 1.1%

[0127] When the number of rare earth composite core-shell particles increases (as in Example 11), the space of the carrier is compressed, resulting in a decrease in lateral crushing strength (41N) and an increase in wear rate (1.2%). Conversely, Example 10, with the lowest active component, exhibits the highest strength (52N) and the lowest wear rate (0.7%).

[0128] When the number of ionic liquid-carbonate complexes increased from 15 parts (Example 12) to 30 parts (Example 13), the chlorine penetration capacity at 120°C significantly increased from 31.2 mg / g to 48.9 mg / g; while the change in the number of rare earth particles (Examples 9, 10, 11) had a negligible effect on the chlorine penetration capacity at 120°C.

[0129] When the number of rare earth composite core-shell particles increased from 15 parts (Example 10) to 35 parts (Example 11), the chlorine penetration capacity at 250°C jumped significantly from 72.5 mg / g to 115.6 mg / g.

[0130] In the high-temperature zone (e.g., 200-300℃), the dechlorination task is mainly undertaken by rare earth composite core-shell particles with high chlorine capacity and passivation resistance. At this time, if the proportion of ionic liquid-carbonate complex is too high (Example 13), since its thermal stability is good but not unlimited, a small amount of decomposed or migrated components will slightly block some pores or active sites of rare earth particles, thereby slightly inhibiting the ultimate chlorine capacity in the high-temperature zone.

[0131] Based on the above measurements, Example 9 is selected as the optimal example.

[0132] Comparative Example 1: The difference between this example and Example 9 is that no rare earth composite core-shell particles were added.

[0133] Comparative Example 2: The difference between this example and Example 9 is that no ionic liquid-carbonate complex was added.

[0134] Comparative Example 3: The difference between this example and Example 9 is that rare earth composite core-shell particles were not added, and cerium oxide and lanthanum manganate were directly physically mixed.

[0135] Comparative Example 4: The difference between this example and Example 9 is that no ionic liquid-carbonate complex was added, and SBA-15 was directly impregnated in carbonate.

[0136] Table 4 Performance data of syngas dechlorination agent

[0137] Lateral crushing strength Chlorine penetration tolerance (120℃) Chlorine penetration tolerance (250℃) Wear rate Example 9 48N 42.5mg / g 98.2 mg / g 0.8% Comparative Example 1 55N 40.1 mg / g 35.4 mg / g 0.7% Comparative Example 2 52N 8.5mg / g 76.8 mg / g 0.9% Comparative Example 3 47N 40.8mg / g 75.6 mg / g 1.0% Comparative Example 4 45N 38.5mg / g 90.1 mg / g 1.1%

[0138] Comparative Example 1 (without rare earth composite core-shell particles) showed a sharp drop in chlorine penetration capacity at 250°C (35.4 mg / g), which was less than 40% of that in Example 9. This proves that rare earth composite core-shell particles are the absolute main force in undertaking deep and high-temperature dechlorination and ensuring overall chlorine capacity. Its higher strength is only due to the increased proportion of inert carrier γ-alumina.

[0139] Comparative Example 2 (without ionic liquid-carbonate complex) almost lost its chlorine penetration capacity (8.5 mg / g) at 120 °C, indicating that the dechlorinating agent is basically ineffective at low temperatures in the absence of ionic liquid complex.

[0140] Meanwhile, the performance of its chlorine penetration capacity at 250℃ (76.8 mg / g) and that of Example 9 (98.2 mg / g) indicates that in the high-temperature region, the dechlorination task is mainly undertaken by rare earth composite core-shell particles. These particles can make full use of the synergistic effect of their oxygen vacancies and perovskite shell at high temperatures to achieve chemical adsorption and catalytic oxidation of HCl. Therefore, even in the absence of ionic liquid complexes, the high-temperature chlorine capacity can still be maintained.

[0141] Comparative Example 3, which uses a physically mixed cerium oxide and lanthanum manganate, has a significantly lower high-temperature chlorine capacity (75.6 mg / g) than Example 9 (98.2 mg / g). This difference demonstrates that simple physical mixing cannot achieve the synergistic effect brought about by the core-shell structure. In the core-shell structure, the oxygen vacancies in the core are tightly coupled with the catalytically active sites in the shell, which can more effectively transfer and convert chlorine species, thereby significantly delaying the "chlorine passivation" phenomenon and releasing a higher chlorine capacity.

[0142] Comparative Example 4 uses the direct impregnation method. Although the chlorine penetration capacity is acceptable, its mechanical strength is the lowest (45N) and the wear rate is the highest (1.1%). More importantly, its active component (carbonate) is only physically attached and is easily lost or migrated during subsequent drying and use (especially when exposed to water or heated), resulting in unstable performance.

[0143] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A syngas dechlorination agent, characterized in that, It includes the following raw materials: γ-alumina, rare earth composite core-shell particles, ionic liquid-carbonate complex, and polyvinyl alcohol; wherein the γ-alumina is 5-10 parts by weight, the rare earth composite core-shell particles are 15-35 parts by weight, the ionic liquid-carbonate complex is 15-30 parts by weight, and the polyvinyl alcohol is 1-3 parts by weight. Rare earth composite core-shell particles are made by reducing nano-cerium oxide with hydrogen at a volume concentration of 5-10% to form an oxygen-rich vacancy core, and then depositing and calcining a lanthanum-manganese precursor on its surface to obtain a coated lanthanum manganate shell. The ionic liquid-carbonate composite is formed by silanizing the surface of SBA-15 with 3-chloropropyltrimethoxysilane and grafting N-methylimidazolium to obtain a surface-immobilized ionic liquid-Cl, followed by impregnation with carbonate and drying to form an immobilized ionic liquid-carbonate composite. The carbonate in the ionic liquid-carbonate composite is potassium carbonate, and the molar ratio of carbonate ions in the potassium carbonate to the surface-immobilized ionic liquid-Cl is 0.5-2.0:

1.

2. The syngas dechlorination agent according to claim 1, characterized in that, The preparation method of the rare earth composite core-shell particles is as follows: Nano-cerium oxide is placed in a tube furnace and first purged with nitrogen for 30 minutes. Then it is treated with hydrogen gas at a volume concentration of 5-10% at 350-450°C for 1-3 hours. After treatment, it is replaced with nitrogen gas, and after returning to room temperature, it is taken out to obtain cerium oxide cores. Citric acid was added to a mixed metal nitric acid solution, with a total molar ratio of citric acid to metal ions of 1:

1. The pH was adjusted to 5-6 with 0.1 mol / L ammonia water, and the solution was stirred at 200-300 rpm to obtain a lanthanum-manganese precursor solution. The cerium oxide cores are ultrasonically dispersed in deionized water at a solid-liquid ratio of 1:20-50 with a power of 100-200W to form a cerium oxide suspension. The lanthanum-manganese precursor solution was added dropwise to the cerium oxide suspension under stirring at 300-400 rpm for 20-60 min. After the addition was completed, stirring was continued for 1-2 h, and the solution was concentrated by evaporation at 60-80 °C under normal pressure. Then, the solution was dried at 80-100 °C for 12 h to obtain a dry powder coated with the precursor. The mass ratio of the lanthanum-manganese precursor solution to the cerium oxide core was 0.05-0.20:

1. The dry powder is placed in a tube furnace, purged with nitrogen for 30 minutes, and then heated to 500-550℃ at a rate of 2-5℃ / min. The temperature is then maintained for 2-4 hours. The powder is cooled to room temperature to obtain rare earth composite core-shell particles.

3. The syngas dechlorination agent according to claim 2, characterized in that, The mixed metal nitric acid solution comprises a 0.2-0.5 mol / L lanthanum nitrate solution and a 0.2-0.5 mol / L manganese nitrate solution, wherein the molar ratio of lanthanum to manganese is 1:

1.

4. The syngas dechlorination agent according to claim 1, characterized in that, The preparation method of the ionic liquid-carbonate complex is as follows: Dry SBA-15 was added to anhydrous toluene at a solid-liquid ratio of 1:20 and ultrasonically dispersed at 100-200W for 5-10 min. Then, 12-15% of 3-chloropropyltrimethoxysilane by mass of SBA-15 was added, and the mixture was stirred at 200-300 rpm for 12 h at 80-90 °C under nitrogen protection. After the reaction, the mixture was cooled to room temperature, washed three times with anhydrous ethanol, filtered, and dried under nitrogen. The mixture was then vacuum dried at 80 °C for 2 h to obtain the support-Cl. The carrier-Cl was dispersed in anhydrous methanol at a solid-liquid ratio of 1:10 and sonicated at 100-200W for 5 min. N-methylimidazolium with a molar ratio of 3:1 to 3-chloropropyltrimethoxysilane was added, and the mixture was stirred at 300-400 rpm for 12-18 h at 50-65 °C under nitrogen protection. After the reaction was completed, the mixture was washed 3-5 times alternately with acetonitrile and ethanol, and then dried under vacuum at 60 °C for 6 h to obtain the surface-immobilized ionic liquid-Cl. The surface-immobilized ionic liquid -Cl was dispersed in deionized water at a solid-liquid ratio of 1:5-10, and 0.5-1.0 mol / L potassium carbonate solution was added. The mixture was stirred at 300-400 rpm for 30-60 min, and then evaporated and concentrated. Under nitrogen atmosphere, it was dried at 120℃ for 2 h, and then the temperature was slowly increased to 150-180℃ and held at this temperature for 2-4 h. Upon cooling, an ionic liquid-carbonate complex is obtained.

5. A method for preparing a syngas dechlorination agent, used to prepare the syngas dechlorination agent as described in any one of claims 1-4, characterized in that, The preparation method of the syngas dechlorination agent is as follows: S1.1 Weigh the following raw materials in parts by weight: 5-10 parts by weight of γ-alumina, 15-35 parts by weight of rare earth composite core-shell particles, 15-30 parts by weight of ionic liquid-carbonate composite, and 1-3 parts by weight of polyvinyl alcohol. S1.

2. Place the γ-alumina, rare earth composite core-shell particles, and ionic liquid-carbonate composite into a mixer and dry mix at 100-200 rpm for 10-15 min; Then add polyvinyl alcohol solution and knead at 200-300 rpm for 15-30 minutes to form a plastic wet material; S1.

3. The wet material is extruded and granulated to obtain wet granules; then pre-drying at 50-60℃ for 2 hours, and then curing and drying at 100-120℃ for 4-6 hours to obtain the syngas dechlorination agent.

6. The method for preparing the syngas dechlorination agent according to claim 5, characterized in that, In step S1.2, the polyvinyl alcohol solution is obtained by adding polyvinyl alcohol to deionized water at a mass ratio of 1:10 and stirring at 300-400 rpm for 1-2 hours at 90°C.

7. The method for preparing the syngas dechlorination agent according to claim 5, characterized in that, In S1.3, the diameter of the wet granules is 2-4 mm; the pressure of the extrusion granulator is 5-10 MPa.