Purifying agent for removing carbonyl iron as well as preparation method and application of purifying agent

Abstract

The invention discloses a purifying agent for removing carbonyl iron as well as a preparation method and application of the purifying agent, and belongs to the field of gas purification. The purifying agent comprises an active carrier and an active component, the active carrier comprises macroporous Al2O3; the active component comprises at least one of a compound of Zn, a compound of Mg, a compound of Ti, a compound of Na, a compound of Si and a compound of Ca. According to the purifying agent obtained by the adopted preparation method, active components are uniformly dispersed in aluminum oxide, surface agglomeration is not prone to occurring, the number of adsorption sites is large, the stability is good, the carbonyl iron removal capacity is high, the purifying agent is used for removing carbonyl iron in dimethyl ether carbonylation reaction raw material gas, the purifying effect is good, and the service life is long. The conversion rate and the service life of the carbonylation catalyst corresponding to the purified feed gas are obviously improved.

Description

Technical Field

[0001] This application relates to a purifying agent for removing carbonyl iron, its preparation method, and its application, belonging to the field of gas purification. Background Technology

[0002] In numerous industrial production processes using syngas as a raw material, the formation of iron carbonyl is a common and significant phenomenon. Taking methanol synthesis as an example, in the gas transportation stage, the CO present in large quantities in the syngas has strong chemical reactivity. It can react chemically with iron elements on the surfaces of the transportation pipelines and related equipment. The reaction process follows the principles of chemisorption and surface reaction. CO molecules first undergo chemisorption on the iron surface, altering the electron cloud distribution of iron atoms and weakening the chemical bonds between iron atoms. Subsequently, under suitable temperature and pressure conditions, CO further reacts with iron to form iron carbonyl. The chemical equation can be represented as: Fe + 5CO → Fe(CO)5. In chemical production using syngas as a feedstock, the presence of iron carbonyl poses serious threats to the production process in several ways, most notably causing catalyst poisoning and deactivation, and triggering a series of side reactions. In the methanol synthesis reaction, the copper-based catalyst plays a crucial role in the efficient execution of the reaction. When iron carbonyl is present in the syngas, it decomposes upon entering the reactor as the reaction temperature increases. The decomposition equation is: Fe(CO)₅ → Fe + 5CO. The resulting metallic iron is deposited as fine particles on the surface of the copper-based catalyst. These iron particles gradually cover the active sites of the catalyst, making it difficult for reactant molecules to contact these sites, thus reducing the catalyst's catalytic activity for the methanol synthesis reaction. As the reaction continues, the amount of iron deposited increases, further reducing the catalyst's activity and ultimately leading to catalyst deactivation. Studies have shown that when the amount of iron deposited on the catalyst surface reaches a certain level, the product distribution of the Fischer-Tropsch synthesis reaction changes significantly, the selectivity of the target product decreases sharply, and the amount of by-products generated increases significantly. To address the hazards of iron carbonyl to industrial production, various methods for removing iron carbonyl have been developed, mainly divided into wet and dry methods. However, these methods all have certain limitations. In wet processes for removing iron carbonyl, direct absorption involves a specific absorbent that reacts directly with the iron carbonyl through physical or chemical reactions, transferring it from the syngas to the liquid phase. However, this method requires specialized absorption towers, circulating pumps, and other equipment, resulting in complex structures and high investment costs. During operation, precise control of parameters such as absorbent flow rate, temperature, and pressure is crucial to ensure absorption efficiency, making the process challenging. Furthermore, the resulting rich solution contains significant impurities and unreacted absorbent, necessitating subsequent treatments such as regeneration and separation. This not only increases the complexity of the process but also generates substantial amounts of wastewater, causing environmental pollution. Oxidative absorption involves adding an oxidant to the absorption system, transforming iron carbonyl into a more readily absorbable substance through oxidation. While this method improves removal efficiency to some extent, it also faces challenges due to its complex equipment, requiring additional oxidation reaction devices and supporting facilities. During operation, conditions such as the amount of oxidant added, reaction time, and reaction temperature must be strictly controlled; otherwise, the removal effect and the lifespan of the absorbent will be affected. Furthermore, the oxidation absorption process generates some byproducts, the treatment of which is also a challenge, increasing production costs and environmental burden. Among dry methods for removing iron carbonyl, physical adsorption using diatomaceous earth microspheres is a common approach. Diatomaceous earth microspheres have a certain specific surface area, enabling them to adsorb iron carbonyl onto their surface through physical adsorption. However, this physical adsorption force is relatively weak, and the adsorption of iron carbonyl is not robust. Under airflow impact or changes in temperature and pressure, the adsorbed iron carbonyl is easily desorbed, resulting in low purification efficiency. Once the diatomaceous earth microspheres are saturated, they cannot be regenerated using simple methods and must be replaced, which not only increases operating costs but also wastes resources. Catalytic removal utilizes the chemical reaction between the active metal of the adsorbent and iron carbonyl, converting it into a harmless or easily separable substance. The most common catalytic removal method is oxidation, which, while capable of removing iron carbonyl to some extent, suffers from insufficient removal precision. For processes with extremely high iron carbonyl content requirements, such as high-end methanol synthesis and fine chemical synthesis, existing catalytic removal methods are insufficient. Furthermore, the adsorption capacity of catalytic removal methods is limited; when processing syngas with high concentrations of iron carbonyl, frequent adsorbent replacements are necessary, increasing operating costs and labor intensity. With the continuous development of modern industry, the scale of chemical production using syngas as raw material is expanding, and the requirements for syngas purification are becoming increasingly stringent. Against this backdrop, the development of a high-precision, high-capacity purifier for removing iron carbonyl is particularly important and urgent. Summary of the Invention According to a first aspect of this application, a purifying agent for removing carbonyl iron is provided. The purifying agent comprises an active support and an active component, wherein the active support is alumina, and the active component is one or more of a Zn, Mg, Ti, Na, Si, and Ca complex.

[0003] A purifying agent for removing iron carbonyl, the purifying agent comprising an active carrier and an active component; The active carrier comprises macroporous Al2O3; The active component includes at least one of the following: a Zn complex, a Mg complex, a Ti complex, a Na complex, a Si complex, and a Ca complex. The Zn complex includes Zn oxides or Zn hydroxyl complexes. The Mg complex includes Mg oxides or Mg hydroxy complexes. The Ti complex includes Ti oxides or Ti hydroxyl complexes; The Na complex includes Na oxides or sodium salts; The Si complex includes Si oxides or silicates; The Ca complexes include Ca oxides or calcium salts.

[0004] Optionally, the purifying agent is composed of an active carrier and active components; The active carrier is macroporous Al2O3; The active component is at least one of a Zn complex, a Mg complex, and a Ti complex.

[0005] Optionally, the active component is at least one of the oxides of Zn, Mg, and Ti.

[0006] Optionally, the active component is at least one of a Zn hydroxyl complex, a Mg hydroxyl complex, and a Ti hydroxyl complex.

[0007] Optionally, the active component is a Zn complex.

[0008] Optionally, the active component is a complex of Zn and a complex of Mg.

[0009] Optionally, the active component is a complex of Zn and a complex of Ti.

[0010] Optionally, the active component is a complex of Zn, a complex of Mg, and a complex of Ti.

[0011] Optionally, the specific surface area of ​​the macroporous Al2O3 is greater than or equal to 150 m². 2 / g.

[0012] Preferably, the specific surface area of ​​the macroporous Al2O3 is 180~350m². 2 / g.

[0013] Optionally, the specific surface area of ​​the macroporous Al2O3 is selected from 150 m². 2 / g、160m 2 / g、170m 2 / g、180m 2 / g、200m 2 / g、220m 2 / g、240m 2 / g、250m 2 / g、260m 2 / g、280m 2 / g、300m 2 / g、320m 2 / g、340m 2 / g, 350m 2 Any value in / g or a range of values ​​between both.

[0014] Optionally, the mass ratio of the active component to the active carrier is 1:5 to 1:60.

[0015] Preferably, the mass ratio of the active component to the active carrier is 1:10 to 1:50.

[0016] Optionally, the mass ratio of the active component to the active carrier is any value or a range between 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, and 1:60.

[0017] In this application, macroporous activated alumina is used as a carrier to provide a "high-quality channel." Furthermore, the surface of macroporous alumina contains a large number of hydroxyl groups (-OH), whose polarity allows them to form van der Waals forces or weak coordination with carbonyl iron (Fe(CO)5 is a weakly polar molecule, and the CO ligand contains lone pairs of electrons). This "captures" Fe(CO)5 molecules in the syngas, enriching them on the carrier surface through the porous structure, preventing them from rapidly passing through the purifier bed with the gas flow, thus creating sufficient time for subsequent chemical transformation. The various active components work synergistically; the Zn, Mg, and Ti complex undergoes a decarbonylation reaction with Fe(CO)5 at high temperature, releasing Fe. 2+ And form a corresponding solid solution, while fixing free Fe with ionic bonds through lattice oxygen and support hydroxyl groups. 2+The Na complex enhances the polarity of the support's hydroxyl groups to improve initial capture efficiency, and also helps lower the reaction energy barrier and reduce component aggregation; the Si complex forms a silica-alumina framework with the support to enhance stability, and its silanol groups expand adsorption sites and help immobilize Fe. 2+ The Ca complex accelerates the dissociation of CO ligands through basic sites, forming a solid solution that immobilizes Fe. 2+ It also prevents the aggregation of other components. The overall system forms a "physical capture-chemical transformation-multiple fixation" system, which is suitable for high temperature and high pressure conditions, and efficiently removes carbonyl iron from the feed gas of dimethyl ether carbonylation, significantly improving the conversion rate and lifespan of subsequent catalysts.

[0018] According to a second aspect of this application, a method for preparing a purifying agent for removing iron carbonyl is provided. The active component element is prepared into a solution in the form of a soluble salt, and then added during the molding process with an active carrier to obtain a precursor. The precursor is then obtained through kneading, molding, drying, and calcination.

[0019] The preparation method of the above-described purifying agent, when the active component includes an oxide corresponding to an active component element, the preparation method includes: A mixed solution containing active component elements is prepared, and then the mixed solution is mixed with activated alumina. Nitric acid is added to obtain a precursor, which is then kneaded, shaped, dried, and calcined to obtain the purifying agent. When the active component includes a hydroxyl complex corresponding to an active component element, the preparation method includes: Nitric acid is added to activated alumina, and after kneading, molding, drying, and calcination (I), γ-Al2O3 is obtained. Then, it is immersed in a salt solution of the active component elements, dried, and calcined (II) to obtain the purifying agent. The temperature of the calcination I is 400~600℃; The calcination temperature II is 100~300℃.

[0020] Optionally, in the mixed solution containing the active component element, the active component element is dissolved in the nitric acid solution in the form of a soluble salt.

[0021] Optionally, the soluble salt corresponding to the active component element is a nitrate.

[0022] Optionally, the preparation of the mixed solution containing the active component element includes: dissolving the soluble salt corresponding to the active component element in nitric acid solution to prepare the mixed solution.

[0023] In this application, the active component element Zn corresponds to zinc nitrate, and the active component element Mg corresponds to magnesium nitrate. When the active component element is Ti, it is added to the solution containing nitric acid in the form of nano-titanium oxide.

[0024] Optionally, the drying temperature is 60~150℃.

[0025] According to a third aspect of this application, an application of a purifying agent for removing iron carbonyl is provided. The removal rate of iron carbonyl reaches over 99.5%. Compared with the feed gas without the purifying agent, the feed gas treated with the purifying agent has an impact of over 20% on the conversion rate of the carbonylation catalyst, and the lifespan can be extended by at least 2000 hours, which can greatly improve the utilization efficiency of the carbonylation catalyst.

[0026] The above-mentioned purifying agent is used to remove iron carbonyl from the feed gas of the dimethyl ether carbonylation reaction.

[0027] Optionally, the purifying agent can be used under the following conditions: reaction temperature of 20~260℃, reaction pressure of 0~7MPa, and space velocity of 100~10000h. -1 .

[0028] Preferably, the conditions for using the purifying agent are: reaction temperature of 20~240℃, reaction pressure of 0~5MPa, and space velocity of 1000~9000h⁻¹. -1 .

[0029] Optionally, the reaction temperature is any value or a range between any two of 20℃, 40℃, 50℃, 60℃, 80℃, 100℃, 120℃, 140℃, 150℃, 160℃, 180℃, 200℃, 220℃, 240℃, 250℃, and 260℃.

[0030] Optionally, the reaction pressure is any value or a range between any two of 0 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, and 7 MPa.

[0031] Optionally, the airspeed is 100 h. -1 200h -1 500h -1 800h -1 1000h -1 2000h -1 3000h -1 4000h -1 5000h -1 6000h -1 7000h -1 8000h -1 9000h -1 10000h -1 Any value in the range or any value between the two.

[0032] The beneficial effects that this application can produce include: The purification agent for removing iron carbonyl provided in this application, its preparation method, and its application are as follows: the purification agent obtained by the preparation method has active components that are uniformly dispersed inside alumina, are not prone to surface aggregation, have many adsorption sites, good stability, and strong removal ability of iron carbonyl. When used to remove iron carbonyl from the feed gas of dimethyl ether carbonylation reaction, it has a good purification effect, and the conversion rate and lifespan of the corresponding carbonylation catalyst in the purified feed gas are significantly improved. Attached Figure Description

[0033] Figure 1 The XRD pattern of the purifying agent prepared in Example 10; Figure 2 The image shows the XRD pattern of the purifying agent prepared in Example 11. Detailed Implementation The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0034] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0035] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0036] In the examples, the concentration of the 8% nitric acid solution was 8 mol / L.

[0037] The concentration of carbonyl metal compounds in the feed gas was determined by gas chromatography with an electron capture detector (GC-ECD).

[0038] Example 1 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 250m²). 2 / g); 5.48g of zinc nitrate hexahydrate was dissolved in 15mL of 8% nitric acid solution to prepare a zinc salt solution; 9.54g of magnesium nitrate hexahydrate was dissolved in 40mL of 8% nitric acid solution to prepare a magnesium salt solution; 1.5g of nano-titanium oxide was added to the above zinc and magnesium salt mixed solution and ultrasonically dispersed for 10min; the mixed solution was slowly added to alumina, and 8% nitric acid solution was added to adjust the pH of the material to 3.0, and kneaded for 30min until a plastic material was formed; the material was extruded into strips, placed in a drying oven, and dried at 60℃ for 8h; then transferred to a muffle furnace and calcined at 400℃ for 4h, and naturally cooled to obtain the purifying agent. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(MgO): m(TiO2): m(Al2O3) = 1: 1: 1: 100.

[0039] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 50 ppm was prepared (the remaining components were dimethyl ether 10 vol%, CO 70 vol%, N2 10 vol%, H2 10 vol%). The reaction conditions were set as follows: temperature 20 °C, pressure 0 MPa (atmospheric pressure), and space velocity 1000 h⁻¹. -1 After the feed gas passes through the purifying agent bed, the concentration of iron carbonyl in the outlet gas is detected by GC-ECD. The results show that iron carbonyl was not detected in the outlet gas (detection limit < 0.001 ppm), and the iron carbonyl removal rate is > 99.9%.

[0040] Example 2 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 250m²). 2 / g); Weigh 5.48g of zinc nitrate hexahydrate and dissolve it in 15mL of 8% nitric acid solution to prepare a zinc salt solution; weigh 9.54g of magnesium nitrate hexahydrate and dissolve it in 20mL of 8% nitric acid solution to prepare a magnesium salt solution; weigh 2.06g of sodium nitrate and dissolve it in 10mL of 8% nitric acid solution to prepare a sodium salt solution; weigh 3.07g of calcium nitrate and 1.5g of nano titanium dioxide, add them to the above mixed solutions of zinc salt, magnesium salt, and sodium salt, and ultrasonically disperse for 10min; slowly add the mixed solution to alumina, continue to add 8% nitric acid solution to adjust the pH of the material to 3.0, and continue to knead for 30min until a plastic material is formed; extrude the material into strips, place them in a drying oven, and dry them at 80℃ for 4h; then transfer them to a muffle furnace and calcine them at 450℃ for 4h, and obtain the purifying agent after natural cooling. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(MgO): m(Na2O): m(CaO): m(TiO2): m(Al2O3) = 1: 1: 0.5: 0.7: 1:100.

[0041] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 50 ppm was prepared (the remaining components were dimethyl ether 10 vol%, CO 70 vol%, N2 10 vol%, H2 10 vol%). The reaction conditions were set as follows: temperature 20 °C, pressure 0 MPa (atmospheric pressure), and space velocity 1000 h⁻¹. -1 After the feed gas passes through the purifying agent bed, the concentration of iron carbonyl in the outlet gas is detected by GC-ECD. The results show that iron carbonyl was not detected in the outlet gas (detection limit < 0.001 ppm), and the iron carbonyl removal rate is > 99.9%.

[0042] Example 3 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 200m²). 2 / g); Weigh 16.45g of zinc nitrate hexahydrate and dissolve it in 15mL of 8% nitric acid solution to prepare a zinc salt solution. Heat the solution to 40℃ and stir to dissolve. Weigh 28.63g of magnesium nitrate hexahydrate and dissolve it in 40mL of 8% nitric acid solution to prepare a magnesium salt solution. Heat the solution to 40℃ and stir to dissolve. Weigh 3g of nano-titanium oxide and add it to the above zinc and magnesium salt mixed solution. Disperse it ultrasonically for 15min. Add the mixed solution to alumina and continue to add 8% nitric acid solution to adjust the pH of the material to 2.8. Knead for 40min until a plastic material is formed. Extrude it into strips, dry it at 80℃ for 6h, and then calcine it at 450℃ for 4h. After cooling, the purifying agent is obtained. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(MgO): m(TiO2): m(Al2O3) = 3: 3: 5: 100.

[0043] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 150 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 120 °C, pressure 2 MPa, and space velocity 1000 h⁻¹. -1 The test results showed that carbonyl iron was not detected in the outlet gas, and the removal rate of carbonyl iron was >99.9%.

[0044] Example 4 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 300m²). 2 / g); Weigh 27.42g of zinc nitrate hexahydrate and dissolve it in 15mL of 8% nitric acid solution to prepare a zinc salt solution. Heat the solution to 40℃ and stir to dissolve. Weigh 47.72g of magnesium nitrate hexahydrate and dissolve it in 40mL of 8% nitric acid solution to prepare a magnesium salt solution. Heat the solution to 40℃ and stir to dissolve. Weigh 7.5g of nano-titanium oxide and add it to the above zinc and magnesium salt mixed solution. Disperse it ultrasonically for 15min. Add the mixed solution to alumina and continue to add 8% nitric acid solution to adjust the pH of the material to 3.2. Knead for 35min until a plastic material is formed. Extrude it into strips, dry it at 110℃ for 4h, and then calcine it at 500℃ for 4h. After cooling, the purifying agent is obtained. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(MgO): m(TiO2): m(Al2O3) = 5: 5: 2: 100.

[0045] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 400 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 200 °C, pressure 4.5 MPa, and space velocity 8000 h⁻¹. -1 The test results showed that the concentration of iron carbonyl in the outlet gas was 0.13 ppm, and the iron carbonyl removal rate was >99.9%.

[0046] Example 5 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 350m²). 2 / g); Weigh 43.87g of zinc nitrate hexahydrate and dissolve it in 15mL of 8% nitric acid solution to prepare a zinc salt solution. Heat the solution to 40℃ and stir to dissolve. Weigh 28.63g of magnesium nitrate hexahydrate and dissolve it in 40mL of 8% nitric acid solution to prepare a magnesium salt solution. Heat the solution to 40℃ and stir to dissolve. Add the mixed solution to alumina, and continue to add 8% nitric acid solution to adjust the pH of the material to 3.1. Knead for 30min until a plastic material is formed. Extrude into strips, dry at 100℃ for 5h, and then calcine at 550℃ for 4h. After cooling, the purifying agent is obtained. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(MgO): m(Al2O3) = 8: 3: 100.

[0047] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 300 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 150 °C, pressure 3 MPa, and space velocity 5000 h⁻¹. -1 The test results showed that the concentration of iron carbonyl in the outlet gas was 0.62 ppm, and the iron carbonyl removal rate was >99.7%.

[0048] Example 6 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 220m²). 2 / g); Weigh 54.84g of zinc nitrate hexahydrate and dissolve it in 15mL of 8% nitric acid solution to prepare a zinc salt solution. Heat the solution to 40℃ and stir to dissolve. Weigh 9.84g of magnesium nitrate hexahydrate and dissolve it in 40mL of 8% nitric acid solution to prepare a magnesium salt solution. Add the mixed solution to alumina, and continue to add 8% nitric acid solution to adjust the pH of the material to 2.9. Knead for 40min until a plastic material is formed. Extrude into strips, dry at 130℃ for 3h, and then calcine at 600℃ for 4h. After cooling, the purifying agent is obtained. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(MgO): m(Al2O3) = 10: 1: 100.

[0049] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 800 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 250 °C, pressure 4.5 MPa, and space velocity 9000 h⁻¹. -1 The test results showed that the concentration of iron carbonyl in the outlet gas was 3.34 ppm, and the iron carbonyl removal rate was >99.5%.

[0050] Example 7 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 250m²). 2 / g); 27.42g of zinc nitrate hexahydrate was dissolved in 15mL of 8% nitric acid solution to prepare a zinc salt solution. The solution was heated to 40℃ and stirred to dissolve. 1.5g of nano-titanium oxide was weighed and added to the above zinc salt solution, and ultrasonically dispersed for 20min. The mixed solution was added to alumina, and 8% nitric acid solution was added to adjust the pH of the material to 3.0. The mixture was kneaded for 30min until a plastic material was formed. The material was extruded, dried at 150℃ for 2h, and then calcined at 600℃ for 3h. After cooling, the purifying agent was obtained. The mass ratio of the active component to the carrier in the purifying agent was: m(ZnO): m(TiO2): m(Al2O3) = 5: 1: 100.

[0051] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a loading volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 600 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 220 °C, pressure 5 MPa, and space velocity 7500 h⁻¹. -1The test results showed that the carbonyl iron concentration in the outlet gas was 1.83 ppm, and the carbonyl iron removal rate was >99.6%; the conversion rate of the carbonylation catalyst corresponding to the purified feed gas was increased by 22%, and the lifespan was extended by 2150 hours.

[0052] Example 8 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 220m²). 2 / g); 16.45g of zinc nitrate hexahydrate was dissolved in 15mL of 8% nitric acid solution to prepare a zinc salt solution. The solution was heated to 40℃ and stirred to dissolve. 9.54g of magnesium nitrate hexahydrate was dissolved in 40mL of 8% nitric acid solution to prepare a magnesium salt solution. 1.5g of nano-titanium oxide was added to the above zinc and magnesium salt mixed solution and ultrasonically dispersed for 20min. The mixed solution was added to alumina, and 8% nitric acid solution was added to adjust the pH of the material to 3.0. The mixture was kneaded for 30min until a plastic material was formed. The material was extruded, dried at 120℃ for 4h, and then calcined at 550℃ for 4h. After cooling, the purifying agent was obtained. The mass ratio of the active component to the carrier in the purifying agent was: m(ZnO): m(MgO): m(TiO2): m(Al2O3) = 3: 1: 1: 100.

[0053] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 700 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 210 °C, pressure 5 MPa, and space velocity 9000 h⁻¹. -1 The test results showed that the carbonyl iron concentration in the outlet gas was 0.08 ppm, and the carbonyl iron removal rate was >99.9%. The conversion rate of the carbonylation catalyst corresponding to the purified feed gas was increased by 18%, and the lifespan was expected to be extended by 1900 hours.

[0054] Example 9 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 220m²). 2 / g); Weigh 16.45g of zinc nitrate hexahydrate and dissolve it in 15mL of 8% nitric acid solution to prepare a zinc salt solution. Heat the solution to 40℃ and stir to dissolve. Weigh 1.23g of sodium nitrate and dissolve it in 10mL of 8% nitric acid solution to prepare a sodium salt solution. Weigh 5.68g of sodium silicate nonahydrate and dissolve it in 10mL of water. Weigh 4.39g of calcium nitrate. Add the zinc salt, sodium salt, and silicate solutions to alumina, and continue to add 8% nitric acid solution to adjust the pH of the material to 3.0. Knead for 30min until a plastic material is formed. Extrude into strips, dry at 110℃ for 4h, and then calcine at 550℃ for 4h. After cooling, the purifying agent is obtained. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(Na2O): m(SiO2): m(CaO): m(Al2O3) = 3: 0.3: 0.8: 1: 100.

[0055] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 600 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 200 °C, pressure 4.5 MPa, and space velocity 8000 h⁻¹. -1 The test results showed that the carbonyl iron concentration was 0.02 ppm and the carbonyl iron removal rate was >99.9%. After running for 4 hours, the carbonyl iron concentration in the outlet gas rose to 2.1 ppm, and the carbonyl iron removal rate was still >99.6%.

[0056] Example 10 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 220m²). 2 / g); Weigh 16.45g of zinc nitrate hexahydrate and dissolve it in 15mL of 8% nitric acid solution to prepare a zinc salt solution. Heat the solution to 40℃ and stir to dissolve. Add the zinc salt solution to alumina, and continue to add 8% nitric acid solution to adjust the pH of the material to 2.9. Knead for 30min until a plastic material is formed. Extrude into strips, dry at 110℃ for 4h, and then calcine at 550℃ for 4h. After cooling, the purifying agent is obtained. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(Al2O3) = 3: 100.

[0057] Figure 1The XRD pattern of the purifying agent prepared in Example 10 is shown. The peaks marked with circles are characteristic peaks of the Zn complex (ZnO), indicating that during calcination, zinc nitrate undergoes decomposition and other reactions, ultimately mainly producing ZnO crystals. The peaks marked with squares are characteristic peaks of γ-Al₂O₃, indicating that boehmite transforms into γ-Al₂O₃ crystals after calcination. The spectrum shows that ZnO and γ-Al₂O₃ have good crystallinity, providing stable active sites and contributing to their role in removing carbonyl iron. The absence of strong diffraction peaks for other impurity phases in the spectrum indicates that after kneading and calcination, ZnO and γ-Al₂O₃ are mainly formed.

[0058] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 600 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 180 °C, pressure 4.5 MPa, and space velocity 7500 h⁻¹. -1 The test results showed that the carbonyl iron concentration was 0.03 ppm, and the carbonyl iron removal rate was >99.9%. After 4 hours of operation, the carbonyl iron concentration in the outlet gas rose to 2.8 ppm, and the carbonyl iron removal rate was still >99.5%. The carbonylation catalyst conversion rate corresponding to the purified feed gas increased by 22%, and its lifespan is expected to be extended by 2200 hours.

[0059] Example 11 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 220m²). 2 Add 8% nitric acid solution to adjust the pH of the material to 3.0, knead for 30 min until a plastic material is formed; extrude into strips, dry at 120℃ for 4 h, then calcine at 550℃ for 4 h, and cool to obtain γ-Al2O3, with a water absorption rate of 55%. Weigh 5.475 g of zinc nitrate hexahydrate and dissolve it in 27.5 mL of water, then take 50 g of γ-Al2O3 and impregnate it using the equal volume impregnation method. Dry at 80℃ for 4 h, then calcine at 140℃ for 4 h, and cool to obtain the purifying agent. The mass ratio of active component to carrier in the purifying agent is: m(ZnO): m(Al2O3) = 3: 100.

[0060] Figure 2The XRD pattern of the purifying agent prepared in Example 11 is shown. The peaks marked with circles are characteristic peaks of the Zn hydroxyl complex, indicating that during calcination, zinc nitrate reacts with the hydroxyl groups in the sample through decomposition and other reactions to form the Zn hydroxyl complex. The peaks marked with squares are characteristic peaks of γ-Al₂O₃, indicating that boehmite is transformed into γ-Al₂O₃ crystals after calcination. The spectrum shows that the Zn hydroxyl complex and γ-Al₂O₃ have good crystallinity, providing stable active sites and contributing to their role in removing carbonyl iron. The absence of strong diffraction peaks for other impurity phases in the spectrum indicates that after impregnation and calcination, the main components formed are the Zn hydroxyl complex and γ-Al₂O₃.

[0061] 2. Application of purification agents A fixed-bed reactor was used. The above-mentioned purifying agent was filled into a reaction tube (10 mm inner diameter) at a loading volume of 1 mL. A dimethyl ether carbonylation reaction feed gas with a carbonyl iron concentration of 700 ppm was prepared (the other components were the same as in Example 1). The reaction conditions were: temperature 200 °C, pressure 4.5 MPa, and space velocity 8500 h⁻¹. -1 The test results showed that the carbonyl iron concentration was 0.05 ppm and the carbonyl iron removal rate was >99.9%. After running for 5 hours, the carbonyl iron concentration in the outlet gas rose to 3.2 ppm, and the carbonyl iron removal rate was still >99.5%.

[0062] Comparative Example 1 (Immersion Method) 1. Preparation of purifying agent Weigh out 150g of activated alumina (BET specific surface area is 220m²). 2 Add 5g of guar gum powder and a certain amount of 8% nitric acid solution; knead for 30 minutes until a plastic material is formed, and extrude it into strips; dry at 110℃ for 4 hours, then calcine at 550℃ for 4 hours, and cool to obtain alumina strip particles; the water absorption rate is measured to be 0.53. Prepare a mixed solution according to the metal components and proportions in Example 8 (the solution volume is 1.2 times the saturated water absorption of alumina); use the traditional equal-volume impregnation method to immerse the alumina strip particles in the mixed solution, let it stand at room temperature for 24 hours, then dry at 110℃ for 4 hours and calcine at 550℃ for 3 hours to prepare the impregnation method purifying agent. 2. Application of purification agents The application conditions were the same as in Example 8. The test results showed that the concentration of iron carbonyl in the outlet gas was 30.81 ppm, and the iron carbonyl removal rate was approximately 95.6%. The results of Example 8 and Comparative Example 1 are shown in Table 1.

[0063] Table 1 Summary of results from Example 8 and Comparative Example 1

[0064] Comparative Example 1 revealed that the traditional impregnation method cannot uniformly disperse the active components inside the alumina, and surface aggregation is prone to occur, resulting in a reduction of adsorption sites and a decrease in stability. The purification effect is significantly different from the kneading molding process of this application.

[0065] Comparative Example 2 (Copper-based purifier) 1. Preparation of purifying agent The purifying agent is derived from existing industrial copper-based purifying agents. It is black in appearance, 3×5mm in size, and has a sheet-like structure.

[0066] 2. Application of purification agents Without H2 reduction, the performance was evaluated directly under the conditions of Example 10. The results showed that the concentration of iron carbonyl in the outlet gas was 356 ppm, far below the purification effect of iron carbonyl. The copper-based purifier was refilled and reduced under 80 vol% N2 and 20 vol% H2 conditions. The reduced purifier was then evaluated under the same conditions as in Example 10. The results showed that the concentration of iron carbonyl in the outlet gas was 7.97 ppm, and the iron carbonyl removal rate was approximately 98.7%. After 4 hours of operation, the purifier activity significantly decreased, the concentration of iron carbonyl in the outlet gas rose to 95.27 ppm, and the removal rate dropped to 84.1%. The results of Example 10 and Comparative Example 2 are shown in Table 2.

[0067] Comparative Example 2 revealed that direct use of copper-based purifiers resulted in poor removal of iron carbonyl; however, reduction treatment under H2 conditions significantly improved the removal of high-concentration iron carbonyl, but the performance deteriorated rapidly.

[0068] Comparative Example 3 (Molecular sieve purifier) 1. Preparation of purifying agent The purifying agent is derived from existing industrial 5A molecular sieves. It is gray in appearance, 3×5mm in size, and has a spherical structure. 2. Application of purification agents The application conditions were the same as in Example 10. The test results showed that the concentration of iron carbonyl in the outlet gas was 230.57 ppm, and the iron carbonyl removal rate was approximately 67.1%. The results of Example 10 and Comparative Example 3 are shown in Table 1.

[0069] Industrially available 5A molecular sieves are mainly composed of elements such as potassium, calcium, sodium, aluminum, silicon, and oxygen. Although they can be used as desiccants and adsorbents, their pore size is relatively small, typically in the range of 0.3~0.5 nm, and they lack effective active metal components, resulting in poor removal capabilities for carbonyl iron.

[0070] Table 2 Summary of results from Example 10 and Comparative Examples 2 and 3

[0071] Conclusion: The comparative examples, due to the use of traditional processes, parameter deviations, or missing key components in their preparation methods, exhibited significantly inferior adsorption activity, stability, and synergistic effect on carbonylation catalysts compared to the examples in this application. This fully demonstrates the innovation and superiority of the purification agent preparation method in this application.

[0072] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A purifying agent for removing iron carbonyl, characterized in that, The purifying agent includes an active carrier and active components; The active carrier comprises macroporous Al2O3; The active component includes at least one of the following: a Zn complex, a Mg complex, a Ti complex, a Na complex, a Si complex, and a Ca complex. The Zn complex includes Zn oxides or Zn hydroxyl complexes. The Mg complex includes Mg oxides or Mg hydroxy complexes. The Ti complex includes Ti oxides or Ti hydroxyl complexes; The Na complex includes Na oxides or sodium salts; The Si complex includes Si oxides or silicates; The Ca complexes include Ca oxides or calcium salts.

2. The purifying agent according to claim 1, characterized in that, The specific surface area of ​​the macroporous Al2O3 is greater than or equal to 150 m². 2 / g; Preferably, the specific surface area of ​​the macroporous Al2O3 is 180~350m². 2 / g.

3. The purifying agent according to claim 1, characterized in that, The mass ratio of the active component to the active carrier is 1:5 to 1:60; Preferably, the mass ratio of the active component to the active carrier is 1:10 to 1:

50.

4. The method for preparing the purifying agent according to any one of claims 1 to 3, characterized in that, When the active component includes an oxide corresponding to an active component element, the preparation method includes: A mixed solution containing active component elements is prepared, and then the mixed solution is mixed with activated alumina. Nitric acid is added to obtain a precursor, which is then kneaded, shaped, dried, and calcined to obtain the purifying agent. When the active component includes a hydroxyl complex corresponding to an active component element, the preparation method includes: Nitric acid is added to activated alumina, and after kneading, molding, drying, and calcination (I), γ-Al2O3 is obtained. Then, it is immersed in a salt solution of the active component elements, dried, and calcined (II) to obtain the purifying agent. The temperature of the calcination I is 400~600℃; The calcination temperature II is 100~300℃.

5. The preparation method according to claim 4, characterized in that, In the mixed solution containing the active component elements, the active component elements are dissolved in the nitric acid solution in the form of soluble salts.

6. The preparation method according to claim 5, characterized in that, The soluble salt corresponding to the active component element is nitrate.

7. The preparation method according to claim 4, characterized in that, The drying temperature is 60~150℃.

8. The application of the purifying agent according to any one of claims 1 to 3 in removing iron carbonyl from the feed gas of the dimethyl ether carbonylation reaction.

9. The application according to claim 8, characterized in that, The operating conditions for the purifying agent are: reaction temperature 20~260℃, reaction pressure 0~7MPa, and space velocity 100~10000h. -1 .

10. The application according to claim 8, characterized in that, The operating conditions for the purifying agent are: reaction temperature 20~240℃, reaction pressure 0~5MPa, and space velocity 1000~9000h⁻¹. -1 .

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