Oxygen adsorbent, method for producing the same, and use thereof

Abstract

The application discloses an oxygen adsorbent and a preparation method and application thereof, and relates to the field of fuel gas deoxygenation. The preparation process of the oxygen adsorbent comprises the following steps: mixing a lanthanum source, a strontium source, an iron source and a titanium source to prepare LSTF precursor powder; loading CeO2 on the LSTF precursor powder; and performing superficial reduction treatment on the LSTF loaded with CeO2, and then loading Fe to prepare an Fe-CeO2-LSTF type adsorbent. The Fe-CeO2-LSTF type adsorbent prepared in the application has a multi-level and reversible oxygen storage network, the network can realize efficient adsorption of oxygen at a low temperature of 100-150 DEG C, and the effect of deep deoxygenation is achieved; and the oxygen can be desorbed at a medium temperature of 220-300 DEG C, and the recycling of the material is realized.

Description

Technical Field

[0001] This application relates to the field of fuel gas deoxygenation, and in particular to an oxygen adsorbent, its preparation method, and its application. Background Technology

[0002] Coal gas is a synthetic gas obtained from coal-based raw materials through processes such as coal gasification, dry distillation, or coking. Its main components include hydrogen, carbon monoxide, methane, carbon dioxide, and small amounts of hydrogen sulfide and nitrogen. Natural gas, on the other hand, is a hydrocarbon gas primarily composed of methane, naturally formed in underground sedimentary rock formations. It has a high calorific value and burns cleanly, and is widely used in city gas, gas turbines, liquefied natural gas (LNG), and as a chemical feedstock. As two major types of fuels, both coal gas and natural gas require extremely low oxygen content during transmission, distribution, storage, and end-use to ensure safe production and use.

[0003] To effectively remove oxygen from coal gas and natural gas, the mainstream oxygen adsorbents currently include activated carbon, carbon molecular sieves, and zeolites. Activated carbon utilizes its high specific surface area for physical adsorption of oxygen, but its adsorption capacity is relatively low. The weak van der Waals interactions between oxygen and non-polar gases such as nitrogen and methane result in poor selectivity, making deep oxygen removal difficult. Carbon molecular sieves primarily rely on physical adsorption through physical sieving; their equilibrium adsorption capacity is similar to that of nitrogen, but their low equilibrium selectivity also hinders deep oxygen removal. Zeolites do not have a superior equilibrium adsorption capacity for oxygen compared to nitrogen, and most zeolites exhibit stronger nitrogen adsorption, further limiting their oxygen removal efficiency. Summary of the Invention

[0004] The main objective of this application is to propose an oxygen adsorbent, its preparation method, and its application, aiming to solve the problem that existing adsorbents are unable to deeply remove oxygen from natural gas and coal gas.

[0005] Firstly, this application provides a process for preparing an oxygen adsorbent, comprising the following steps:

[0006] S1. Provide water, add lanthanum source, strontium source, iron source and titanium source to the water, stir, add citric acid and adjust the pH to 6~7 to obtain sol, place the sol at 70~90℃ and stir for 8~12h, dry and grind, keep the ground powder at 400~500℃ for 2~5h to obtain LSTF precursor powder;

[0007] S2. Polyvinylpyrrolidone is added to an aqueous solution containing a cerium source, the pH is adjusted to 8.5-9.5, the LSTF precursor powder obtained in step S1 is added, and the mixture is ultrasonically dispersed. The dispersed mixture is placed in a closed hydrothermal reactor and reacted at 120-180℃ for 10-15 hours. The mixture is then removed and subjected to solid-liquid separation, washing and drying. It is then kept at 600-700℃ for 3-5 hours to obtain CeO2-LSTF.

[0008] S3. Place the CeO2-LSTF obtained in step S2 in a hydrogen reducing atmosphere, heat it to 300-400°C at a heating rate of 3-7°C / min, maintain it at this temperature for 0.5-1h, introduce argon gas, and cool it to room temperature.

[0009] S4. The product obtained by cooling in step S3 is immersed in a 0.5-2 mol / L iron triacetylacetone solution for 10-15 h. Solid-liquid separation is performed. The solid obtained by solid-liquid separation is placed under a nitrogen protective atmosphere and the temperature is controlled at 350-400℃. The solid is kept at this temperature for 2-4 h to obtain Fe-CeO2-LSTF type adsorbent.

[0010] By employing the above-mentioned technical solution, using lanthanum, strontium, iron, and titanium sources as raw materials, and employing the sol-gel method combined with medium-temperature pre-calcination, LSTF perovskite precursor powder was prepared. Using the LSTF perovskite precursor powder as a carrier, a cerium source was loaded, followed by high-temperature calcination and interface solidification to obtain CeO2-LSTF. The specific preparation process described above yields LSTF perovskite carriers with good structural rigidity, high temperature resistance, and corrosion resistance, providing stable support for the dispersion of CeO2 and subsequent Fe. It can also form oxygen migration channels at the CeO2-Fe interface, providing a large number of lattice oxygen vacancies, enabling rapid diffusion and storage of oxygen within the solid. The CeO2 surface is rich in hydroxyl groups and defect sites, readily adsorbing oxygen, and oxygen can also be absorbed through CeO2. 4+ / Ce 3+ Electron transfer enables chemisorption, allowing for rapid capture of oxygen. It interacts with oxygen vacancies in the LSTF, resulting in oxygen migration / compensation and increasing overall oxygen storage.

[0011] CeO2-LSTF was subjected to a low-temperature, mild reduction treatment in a hydrogen reducing atmosphere to introduce controlled and appropriately deep oxygen vacancies on the material surface, thereby anchoring Fe more stably and uniformly, resulting in a Fe-CeO2-LSTF type adsorbent. The surface hydroxyl groups of iron form a strong interfacial coupling with CeO2 and LSTF. Iron exhibits reversible divalent and trivalent oxidation states, providing a second set of chemisorption for the adsorbent, further enhancing its oxygen capture capacity. In the Fe-CeO2-LSTF type adsorbent, oxygen atoms generated from Fe decomposition rapidly migrate through the Fe-CeO2 / Fe-LSTF interface to oxygen vacancies on the CeO2 surface or in the LSTF lattice, where they combine accordingly, achieving efficient oxygen adsorption. The Fe-CeO2-LSTF type adsorbent forms a multi-layered, reversible oxygen storage network that can achieve efficient oxygen adsorption at low temperatures of 100–150 °C, achieving deep oxygen removal. Furthermore, oxygen desorption can be carried out at a medium temperature of 220~300℃, enabling the recycling of materials.

[0012] When loading CeO2, polyvinylpyrrolidone is added. The unique steric hindrance effect and coordination ability of polyvinylpyrrolidone can be used to uniformly disperse the cerium source, ensuring that the cerium source is fully loaded on the LSTF precursor powder. It also helps to improve the uniform loading of CeO2 formed on the LSTF support during the high-temperature calcination and interface curing process.

[0013] Optionally, in step S3, cooling to room temperature includes: cooling to 120-150°C at a cooling rate of 15-25°C / min, and then cooling to room temperature at a cooling rate of 1-5°C / min.

[0014] By employing the above technical solution, CeO2-LSTF is placed in a hydrogen reducing atmosphere for a low-temperature, gentle reduction treatment to introduce controlled oxygen vacancies at an appropriate depth on the material surface, thereby anchoring Fe more stably and uniformly. After reduction, the hydrogen reducing atmosphere is switched to argon, and argon flow is used for cooling to effectively isolate oxygen, prevent the disappearance of the formed oxygen vacancies, and control an appropriate cooling rate to effectively lock the controlled defects on the material surface. Too rapid a cooling rate can cause lattice stress defects, while too slow a cooling rate can lead to changes in the controlled defects. When the temperature drops to 120-150℃, a slower cooling rate is applied to reduce thermal shock and maintain the locked structure more stably.

[0015] Optionally, in step S3, the hydrogen reducing atmosphere comprises 1% hydrogen by volume and 99% nitrogen by volume.

[0016] By adopting the above technical solution and controlling the volume percentage of hydrogen and nitrogen, controlled and appropriately deep oxygen vacancies are introduced into the material surface.

[0017] Optionally, in step S2, the polyvinylpyrrolidone is acrylic acid-modified polyvinylpyrrolidone, and the preparation method of the acrylic acid-modified polyvinylpyrrolidone includes:

[0018] S21. Polyvinylpyrrolidone, sodium hypophosphite and acrylic acid are added to water to obtain the first mixture;

[0019] S22. Add ammonium persulfate to water to obtain a second mixture;

[0020] S23. Under nitrogen protection, the first mixture and the second mixture are mixed, the temperature is controlled at 70~90℃, the mixture is stirred and reacted for 1~2 hours, cooled, and the pH is adjusted to 5.5~7.0 to obtain acrylic acid modified polyvinylpyrrolidone.

[0021] By adopting the above technical solution, acrylic acid-modified polyvinylpyrrolidone is used to introduce carboxyl groups onto polyvinylpyrrolidone, which improves the coordination ability of polyvinylpyrrolidone, significantly enhances the fixation and dispersion of cerium source on the support, and also improves the uniform loading of CeO2 formed on the LSTF support during high-temperature calcination and interface curing, thus ensuring the crystal structure of the material.

[0022] Optionally, in step S21, the polyvinylpyrrolidone is polyvinylpyrrolidone K60.

[0023] By adopting the above technical solution and controlling the molecular weight of polyvinylpyrrolidone, suitable steric hindrance effect and coordination ability are obtained, ensuring the fixation and dispersion of the cerium source on the support.

[0024] Optionally, in step S21, polyvinylpyrrolidone includes polyvinylpyrrolidone K60 and polyvinylpyrrolidone K30, and the weight ratio of polyvinylpyrrolidone K60 to polyvinylpyrrolidone K30 is (1.5~2.5):1.

[0025] Preferably, the weight ratio of the polyvinylpyrrolidone K60 to the polyvinylpyrrolidone K30 is 2:1.

[0026] By adopting the above technical solution, and further optimizing the polyvinylpyrrolidone obtained by compounding two polyvinylpyrrolidones with specific molecular weights, the high molecular weight polyvinylpyrrolidone has a stronger steric hindrance effect, while the low molecular weight polyvinylpyrrolidone has a certain degree of deep penetration. By using two molecular weight polyvinylpyrrolidones, the effects of dispersion stability and penetration can be taken into account, and an alternating coordination effect can be produced, so as to achieve a more sufficient and stable loading of the cerium source on the carrier.

[0027] Optionally, in step S2, the cerium source is cerium nitrate hexahydrate, and the weight ratio of cerium nitrate hexahydrate to polyvinylpyrrolidone is 1.41:(0.15~0.28).

[0028] By adopting the above technical solution and controlling the amount of polyvinylpyrrolidone, the cerium source can be loaded onto the carrier more uniformly and stably.

[0029] Optionally, in step S1, the lanthanum source is lanthanum nitrate, the strontium source is strontium nitrate, the titanium source is tetrabutyl titanate, and the iron source is ferric nitrate, and the molar ratio of the lanthanum nitrate, the strontium nitrate, the tetrabutyl titanate, and the ferric nitrate is 0.6:0.4:0.4:0.6.

[0030] By adopting the above technical solution, using lanthanum nitrate as the lanthanum source, strontium nitrate as the strontium source, tetrabutyl titanate as the titanium source, and ferric nitrate as the iron source, and controlling the proportion of each component, the resulting LSTF crystal structure is guaranteed to have good rigidity and high temperature resistance, and can increase a large number of mobile lattice oxygen vacancies, thereby realizing the rapid diffusion and storage of oxygen inside the solid.

[0031] Secondly, this application proposes an adsorbent prepared using the preparation process of an oxygen adsorbent as described in any of the above claims.

[0032] By adopting the above technical solution, the Fe-CeO2-LSTF type adsorbent provided in this application can achieve efficient oxygen adsorption at low temperatures of 100~150℃, achieving deep oxygen removal. Furthermore, oxygen desorption can occur at medium temperatures of 220~300℃, enabling the material to be recycled.

[0033] Thirdly, this application also proposes the application of the adsorbent as described above in removing oxygen from coal gas and natural gas.

[0034] By adopting the above technical solution, the Fe-CeO2-LSTF type adsorbent can effectively adsorb oxygen from coal gas and natural gas, achieving high oxygen adsorption efficiency and deep deoxygenation. Furthermore, oxygen desorption can occur at a moderate temperature of 220~300℃, enabling the material to be recycled.

[0035] In summary, this application includes at least one of the following beneficial technical effects:

[0036] 1. The Fe-CeO2-LSTF type adsorbent prepared in this application has a multi-layered, reversible oxygen storage network. This network can achieve efficient oxygen adsorption at low temperatures of 100~150℃, achieving deep oxygen removal. Furthermore, oxygen desorption can occur at intermediate temperatures of 220~300℃, enabling the material to be recycled.

[0037] 2. Using lanthanum, strontium, iron, and titanium sources as raw materials, LSTF perovskite precursor powder was prepared via a sol-gel method combined with medium-temperature pre-calcination. The LSTF perovskite precursor powder was then used as a carrier to load a cerium source, followed by high-temperature calcination and interfacial solidification to obtain CeO2-LSTF. The resulting LSTF perovskite carrier exhibits good structural rigidity, high temperature resistance, and corrosion resistance, providing stable support for the dispersion of CeO2 and subsequent Fe. It also forms oxygen migration channels at the CeO2-Fe interface, providing a large number of lattice oxygen vacancies, enabling rapid diffusion and storage of oxygen within the solid.

[0038] 3. CeO2-LSTF is placed in a hydrogen reducing atmosphere and subjected to a low-temperature, mild reduction treatment to introduce controlled and appropriately deep oxygen vacancies on the material surface, thereby anchoring Fe more stably and uniformly, resulting in a Fe-CeO2-LSTF type adsorbent. Iron exhibits reversible divalent and trivalent oxidation states, providing a second set of chemisorption for the adsorbent and further enhancing its oxygen capture capacity. In the Fe-CeO2-LSTF type adsorbent, oxygen atoms generated from Fe decomposition rapidly migrate through the Fe-CeO2 / Fe-LSTF interface to oxygen vacancies on the CeO2 surface or in the LSTF lattice, where they combine accordingly, achieving highly efficient oxygen adsorption.

[0039] 4. When loading CeO2, polyvinylpyrrolidone is added. The unique steric hindrance effect and coordination ability of polyvinylpyrrolidone can be used to uniformly disperse the cerium source, ensuring that the cerium source is fully loaded on the LSTF precursor powder. It also helps to improve the uniform loading of CeO2 formed on the LSTF carrier during the high-temperature calcination and interface curing process. Detailed Implementation

[0040] The present application will be further described in detail below with reference to the embodiments. All raw materials involved in the embodiments are commercially available, wherein...

[0041] Polyvinylpyrrolidone K30, Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.;

[0042] Polyvinylpyrrolidone K60, Wuhan Lanabai Pharmaceutical Chemical Co., Ltd. Example 1

[0043] A process for preparing an oxygen adsorbent includes the following steps:

[0044] S1. Provide 80 mL of deionized water, add 5.98 g of lanthanum nitrate hexahydrate [La(NO3)3∙6H2O] and 1.95 g of strontium nitrate [Sr(NO3)2] to the water, and stir at 200 rpm for 15 min to obtain mixture A; dissolve 5.58 g of ferric nitrate nonahydrate [Fe(NO3)3∙9H2O] in 30 mL of deionized water to obtain an iron solution; add 3.13 g of titanate n-butyl ester to 20 mL of n-butanol, and stir at 200 rpm for 10 min to obtain a titanium solution; add the iron solution and titanium solution to mixture A, and stir at 200 rpm. The system was stirred at a stirring rate of 100 rpm for 10 hours to obtain a sol. The sol was then placed in a constant temperature oil bath at 80 ℃ and stirred at a stirring rate of 100 rpm for 10 hours. After drying at 110 ℃ for 12 hours, the sol was ground and sieved to obtain a powder with an average particle size of 110 μm. The powder was then placed in a tube furnace and heated to 450 ℃ at a heating rate of 3 ℃ / min. The temperature was maintained at this temperature for 3 hours and then allowed to cool naturally to obtain the LSTF precursor powder.

[0045] S2. Add 1.41g of cerium nitrate hexahydrate [Ce(NO3)3∙6H2O] to 80mL of deionized water and stir magnetically for 10min. Add 0.23g of polyvinylpyrrolidone K60 and stir magnetically for 15min. Add 10wt% ammonia solution dropwise to adjust the pH of the system to 9, obtaining mixture B. Add the LSTF precursor powder obtained in step S1 to an ethanol solution (5mL of anhydrous ethanol and 30mL of deionized water) and stir magnetically for 5min to obtain a suspension. Add the suspension to mixture B and ultrasonically disperse at 200W for 15m. The dispersed mixture was placed in a sealed hydrothermal reactor and the temperature was controlled at 150℃. The mixture was stirred at 100 rpm for 12 h. The mixture was then removed and centrifuged at 4000 rpm for 5 min to obtain a solid. The solid was washed with deionized water and anhydrous ethanol in sequence to complete one washing. The solid was then washed twice more in the same manner. The washed solid was dried at 80℃ for 12 h. The dried solid was then placed in a muffle furnace and heated to 650℃ at a heating rate of 3℃ / min. The solid was held at this temperature for 4 h and then allowed to cool naturally to obtain CeO2-LSTF.

[0046] S3. Place the CeO2-LSTF obtained in step S2 in a hydrogen reducing atmosphere (1% hydrogen by volume and 99% nitrogen by volume), heat it to 300°C at a heating rate of 5°C / min, hold it at this temperature for 45 min, introduce argon gas, cool it to 150°C at a cooling rate of 15°C / min, and then cool it to 25°C at a cooling rate of 5°C / min to obtain the cooled product.

[0047] S4. Dissolve ferric triacetylacetonate in anhydrous ethanol to obtain a 1 mol / L ferric triacetylacetonate solution. Take 80 mL of the 1 mol / L ferric triacetylacetonate solution and add the cooled product obtained in step S3 to the ferric triacetylacetonate solution. Soak for 12 h, filter to remove the solution, and obtain a solid. Dry the solid under vacuum at 70 °C for 8 h, place it in a nitrogen protective atmosphere, heat it to 380 °C at a heating rate of 2 °C / min, and hold it at this temperature for 3 h to obtain calcined powder. Extrude the calcined powder into spherical bodies with an average diameter of 3 mm to obtain Fe-CeO2-LSTF type adsorbent.

[0048] Examples 2-3

[0049] Examples 2 and 3 are based on Example 1, the difference being that in step S3, the cooling conditions to room temperature are changed, while the other steps remain the same as in Example 1. Specifically,

[0050] Step S3 of Example 2: The CeO2-LSTF obtained in step S2 was placed in a hydrogen reducing atmosphere (1% hydrogen by volume and 99% nitrogen by volume), heated to 300°C at a heating rate of 5°C / min, held at this temperature for 45 min, argon was introduced, and the temperature was lowered to 145°C at a cooling rate of 20°C / min, and then lowered to 25°C at a cooling rate of 4°C / min to obtain the cooled product.

[0051] Step S3 of Example 3: The CeO2-LSTF obtained in step S2 was placed in a hydrogen reducing atmosphere (1% hydrogen by volume and 99% nitrogen by volume), heated to 300°C at a heating rate of 5°C / min, held at this temperature for 45 min, argon was introduced, and the temperature was lowered to 140°C at a cooling rate of 25°C / min, and then lowered to 25°C at a cooling rate of 2°C / min to obtain the cooled product. Example 4

[0052] This embodiment is based on Example 2, the difference being that in step S2, 0.23g of acrylic acid-modified polyvinylpyrrolidone is used instead of 0.23g of polyvinylpyrrolidone K60 in Example 2, and the other steps are the same as in Example 2.

[0053] The preparation method of acrylic acid-modified polyvinylpyrrolidone in this embodiment includes the following steps:

[0054] (1) Mix polyvinylpyrrolidone K60, sodium hypophosphite, acrylic acid and deionized water in a mass ratio of 11.2:0.6:7.6:30 to obtain the first mixture for later use;

[0055] (2) Mix ammonium persulfate and deionized water at a mass ratio of 0.45:35 to obtain a second mixture for later use;

[0056] (3) Take 50g of the first mixture and place it in an oil bath container at 80℃. Pour nitrogen into the oil bath container and stir the first mixture at a stirring speed of 100rpm. Add 36g of the second mixture to the first mixture. After the addition is complete, keep it in a constant temperature oil bath at 80℃ for 2h and cool it naturally to 25℃. Adjust the pH of the system to 6.2 with a sodium hydroxide solution with a concentration of 1mol / L to obtain acrylic acid modified polyvinylpyrrolidone.

[0057] Examples 5-6

[0058] Examples 5 and 6 are based on Example 4, except that the amount of acrylic acid-modified polyvinylpyrrolidone used in step S2 is changed; the other steps remain the same as in Example 4. Specifically,

[0059] In Example 5, the amount of acrylic acid-modified polyvinylpyrrolidone used was 0.15g.

[0060] In Example 6, the amount of acrylic acid-modified polyvinylpyrrolidone used was 0.28g. Example 7

[0061] This embodiment is based on Example 4, the difference being that in step (1), a mixture of polyvinylpyrrolidone K60 and polyvinylpyrrolidone K30 is used to replace polyvinylpyrrolidone K60, and the total weight of polyvinylpyrrolidone K60 and polyvinylpyrrolidone K30 is the same as the weight of polyvinylpyrrolidone K60 in Example 4. In this example, polyvinylpyrrolidone K60 and polyvinylpyrrolidone K30 are mixed in a weight ratio of 2:1, and the other steps are the same as in Example 4. Comparative Example 1

[0062] This comparative example is based on Example 1, the difference being that step S3 is omitted. Step S4 in this example is as follows: iron triacetylacetonate is dissolved in anhydrous ethanol to obtain a 1 mol / L iron triacetylacetonate solution. 80 mL of the 1 mol / L iron triacetylacetonate solution is taken, and CeO2-LSTF obtained in step S2 is added to the iron triacetylacetonate solution. The solution is impregnated for 12 h, filtered to remove the solution, and a solid is obtained. The solid is dried under vacuum at 70 °C for 8 h, placed in a nitrogen protective atmosphere, and heated to 380 °C at a heating rate of 2 °C / min. The temperature is maintained at this temperature for 3 h to obtain calcined powder. The calcined powder is extruded into spherical bodies with an average diameter of 3 mm to obtain the adsorbent. Comparative Example 2

[0063] This comparative example is based on Example 1, the difference being that the cooling rate during cooling to room temperature in step S3 is different, while the other steps remain the same as in Example 1. Specifically,

[0064] Step S3 of this comparative example: The CeO2-LSTF obtained in step S2 was placed in a hydrogen reducing atmosphere (1% hydrogen by volume and 99% nitrogen by volume), heated to 300°C at a heating rate of 5°C / min, held at this temperature for 45 min, then argon was introduced, and cooled to 25°C at a cooling rate of 15°C / min to obtain the cooled product. Comparative Example 3

[0065] This comparative example is based on Example 1, the difference being that the cooling rate during cooling to room temperature in step S3 is different, while the other steps remain the same as in Example 1. Specifically,

[0066] Step S3 of this comparative example: The CeO2-LSTF obtained in step S2 was placed in a hydrogen reducing atmosphere (1% hydrogen by volume and 99% nitrogen by volume), heated to 300°C at a heating rate of 5°C / min, held at this temperature for 45 min, then argon was introduced, and cooled to 25°C at a cooling rate of 5°C / min to obtain the cooled product.

[0067] Performance Test 1

[0068] Oxygen adsorption tests were conducted on the adsorbents prepared in Examples 1-7 and Comparative Examples 1-3. The test methods are as follows:

[0069] 2g of adsorbent was placed in a fixed-bed reactor. The experimental conditions were: the simulated gas contained 2000ppm O2, the equilibrium gas was N2, the total inlet flow rate was 120mL / min, and the space velocity ratio was 2000 h⁻¹. -1The temperature was 130℃. After 5 minutes of testing, the oxygen concentration in the gas discharged from the outlet was measured to obtain the oxygen removal rate (%). The experimental results are shown in Table 1 below.

[0070] Wherein, oxygen removal rate = [(C0-C1) / C0]×100%; C0 is the oxygen concentration in the gas to be purified input through the inlet, and C1 is the oxygen concentration in the gas after adsorption treatment discharged through the outlet.

[0071] Table 1 Oxygen Removal Rate

[0072]

[0073] Performance Test 2

[0074] After adsorbing oxygen in performance test 1, the adsorbent was placed in a nitrogen environment and heated to 250℃ to desorb oxygen for 1 hour. The adsorbent after desorption was then subjected to the same adsorption method as in performance test 1, and the oxygen removal rate was tested. The test results are shown in Table 2 below.

[0075] Table 2 Oxygen removal rate after desorption treatment

[0076]

[0077] As shown in Tables 1 and 2, the Fe-CeO2-LSTF type adsorbent prepared in this application possesses a multi-layered, reversible oxygen storage network. This network can achieve efficient oxygen adsorption at low temperatures of 100–150°C, achieving deep oxygen removal. Furthermore, oxygen desorption can occur at intermediate temperatures of 220–300°C, enabling the material to be recycled.

[0078] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the principles of this application should be covered within the scope of protection of this application.

Claims

1. A preparation process for an oxygen adsorbent, characterized in that, Includes the following steps: S1. Provide water, add lanthanum source, strontium source, iron source and titanium source to the water, stir, add citric acid and adjust the pH to 6~7 to obtain sol, place the sol at 70~90℃ and stir for 8~12h, dry and grind, keep the ground powder at 400~500℃ for 2~5h to obtain LSTF precursor powder; S2. Polyvinylpyrrolidone is added to an aqueous solution containing a cerium source, the pH is adjusted to 8.5-9.5, the LSTF precursor powder obtained in step S1 is added, and the mixture is ultrasonically dispersed. The dispersed mixture is placed in a closed hydrothermal reactor and reacted at 120-180℃ for 10-15 hours. The mixture is then removed and subjected to solid-liquid separation, washing and drying. It is then kept at 600-700℃ for 3-5 hours to obtain CeO2-LSTF. S3. Place the CeO2-LSTF obtained in step S2 in a hydrogen reducing atmosphere, heat it to 300-400°C at a heating rate of 3-7°C / min, maintain it at this temperature for 0.5-1h, introduce argon gas, and cool it to room temperature. S4. The product obtained by cooling in step S3 is immersed in a 0.5-2 mol / L iron triacetylacetone solution for 10-15 h, and the solid and liquid are separated. The solid obtained by solid-liquid separation is placed under a nitrogen protective atmosphere and the temperature is controlled at 350-400℃. The solid is kept at this temperature for 2-4 h to obtain Fe-CeO2-LSTF type adsorbent. In step S3, cooling to room temperature includes: cooling to 120-150°C at a cooling rate of 15-25°C / min, and then cooling to room temperature at a cooling rate of 1-5°C / min. In step S1, the lanthanum source is lanthanum nitrate, the strontium source is strontium nitrate, the titanium source is tetrabutyl titanate, and the iron source is ferric nitrate. The molar ratio of the lanthanum nitrate, the strontium nitrate, the tetrabutyl titanate, and the ferric nitrate is 0.6:0.4:0.4:0.

6.

2. The preparation process of the oxygen adsorbent according to claim 1, characterized in that, In step S3, the hydrogen reducing atmosphere comprises 1% hydrogen by volume and 99% nitrogen by volume.

3. The preparation process of the oxygen adsorbent according to claim 1, characterized in that, In step S2, the polyvinylpyrrolidone is acrylic acid-modified polyvinylpyrrolidone, and the preparation method of the acrylic acid-modified polyvinylpyrrolidone includes: S21. Polyvinylpyrrolidone, sodium hypophosphite and acrylic acid are added to water to obtain the first mixture; S22. Add ammonium persulfate to water to obtain a second mixture; S23. Under nitrogen protection, the first mixture and the second mixture are mixed, the temperature is controlled at 70~90℃, the mixture is stirred and reacted for 1~2 hours, cooled, and the pH is adjusted to 5.5~7.0 to obtain acrylic acid modified polyvinylpyrrolidone.

4. The preparation process of the oxygen adsorbent according to claim 3, characterized in that, In step S21, the polyvinylpyrrolidone is polyvinylpyrrolidone K60.

5. The preparation process of the oxygen adsorbent according to claim 3, characterized in that, In step S21, polyvinylpyrrolidone includes polyvinylpyrrolidone K60 and polyvinylpyrrolidone K30, and the weight ratio of polyvinylpyrrolidone K60 to polyvinylpyrrolidone K30 is (1.5~2.5):

1.

6. The preparation process of the oxygen adsorbent according to claim 3, characterized in that, In step S2, the cerium source is cerium nitrate hexahydrate, and the weight ratio of cerium nitrate hexahydrate to polyvinylpyrrolidone is 1.41:(0.15~0.28).

7. An adsorbent prepared using the preparation process of the oxygen adsorbent as described in any one of claims 1 to 6.

8. The application of the adsorbent as described in claim 7 in removing oxygen from coal gas and natural gas.

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