Adsorbent for removing COS in natural gas by low temperature and method for preparing the same

Abstract

The application discloses an adsorbent for removing COS in natural gas by low-temperature and anti-CO2 competitive adsorption and a preparation method thereof, and belongs to the technical field of adsorbent preparation. The method comprises the following steps: firstly, dissolving melamine and sodium alginate in deionized water at room temperature to obtain a colloidal dispersion system; dissolving glucose in the colloidal dispersion system to obtain a melamine-sodium alginate-glucose ternary composite water-based viscous colloid; then, adding the melamine-sodium alginate-glucose ternary composite water-based viscous colloid into an aqueous solution containing metal ions, and stirring and standing at room temperature to obtain water-bonding beads with a 3D reticular porous structure; washing and freeze-drying the water-bonding beads to obtain air-bonding beads; and finally, carbonizing the air-bonding beads under a nitrogen atmosphere, and the adsorbent is obtained. The adsorbent prepared by the method has high adsorption efficiency at a low-temperature section, such as 40 DEG C, and can efficiently remove COS in natural gas under the condition of CO2.

Description

Technical Field

[0001] This invention belongs to the field of adsorbent preparation technology, specifically relating to an adsorbent for low-temperature removal of COS from natural gas and its preparation method. Background Technology

[0002] Natural gas, as a high-quality clean energy source and a basic raw material for chemical engineering, occupies a crucial position in the transformation of the energy structure and the advancement of the "dual carbon" goal. With the continuous growth of my country's energy demand and the comprehensive coverage of long-distance natural gas pipelines, the clean utilization of natural gas has become a core demand of the industry. However, in addition to the main hydrocarbon components, raw natural gas also contains a variety of acidic gases and impurities. Among them, carbonyl sulfide (COS), as a typical organic sulfur compound, has become a key technological bottleneck for the deep purification of natural gas due to its stable chemical properties, difficulty in dissociation, and difficulty in liquefaction.

[0003] The volume fraction of carbonyl sulfide (COS) in natural gas is generally in the range of 0-100 ppm. Although its content is lower than that of hydrogen sulfide (H2S), its removal and treatment are far more difficult. Its core hazards are mainly reflected in three aspects: First, corrosion risk: COS slowly hydrolyzes to generate H2S in the presence of water, exacerbating corrosion and wear on pipelines and equipment, and shortening the service life of industrial plants. Second, catalyst poisoning: When natural gas is used as a chemical feedstock (such as in the production of synthetic ammonia and methanol), trace amounts of COS can cause permanent deactivation of precious metal and transition metal catalysts in downstream processes. Third, environmental and compliance risks: COS combustion generates sulfur oxides, causing environmental problems such as acid rain and ozone layer depletion.

[0004] Existing research reports on the removal of carbonyl sulfides include: Application No. 202010597608.2 discloses a composite catalytic adsorbent for removing carbonyl sulfides, which is prepared by drying a catalytic support and a catalytically active substance under the action of an alkaline binder. The catalytically active substance is a mixture of activated alumina and calcium citrate. The operating conditions of this catalyst are 40–800℃. This patent application, by setting a catalyst with a catalytic support and a catalytically active substance, enables the decomposition reaction of carbonyl sulfides under weakly alkaline conditions, thus decomposing carbonyl sulfides. It innovatively uses an adsorbent in conjunction with the catalyst to pre-treat the carbonyl sulfides, reducing catalyst poisoning. However, the optimal operating range of this catalyst is 400–800℃, with low efficiency in the low-temperature range of 40–200℃. Its applicable conditions are biased towards high temperatures, with insufficient activity at low temperatures, and it has weak resistance to carbon dioxide and water vapor. Application No. 201911025500.X discloses an adsorbent for removing carbonyl sulfides, its preparation method, and its application. The preparation steps are as follows: 1) contacting an alkaline earth metal oxide with a weakly acidic or neutral solution, then drying and pulverizing the resulting mixture to obtain adsorbent powder; 2) granulating the adsorbent powder or mixing the adsorbent powder with a binder and then granulating to obtain adsorbent particles. The application scope of the adsorbent in this patent application is limited to olefin systems, exhibiting narrow applicability, and no research has been conducted on natural gas operating conditions.

[0005] It is evident that existing adsorbents and catalysts for COS removal often suffer from insufficient active sites, poor selectivity, weak stability, and susceptibility to CO2 poisoning. During high-temperature pyrolysis to prepare desulfurization carbon materials, the support and active components readily react with carbon dioxide in the system, leading to damage to the pore structure and failure of active sites, significantly weakening the material's desulfurization capacity in a carbon dioxide-containing atmosphere. Overcoming the challenge of carbon dioxide interference and developing carbonyl sulfide removal materials with both high selectivity and high activity has become a key bottleneck in the technological development of the natural gas purification field. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2. The adsorbent prepared by this method has high adsorption efficiency at low temperatures, such as 40°C, and can efficiently remove COS from natural gas under CO2 conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a low-temperature adsorbent for COS removal from natural gas that resists CO2 competitive adsorption includes the following steps: a. Melamine and sodium alginate are dissolved in deionized water at room temperature to obtain a colloidal dispersion system; the mass-to-volume ratio of melamine, sodium alginate and deionized water is 0.5-1.0 g: 100 mL. b. Weigh 1-2.5g of glucose and dissolve it in the colloidal dispersion system to obtain a melamine-sodium alginate-glucose ternary composite water-based viscous colloid. c. Containing Cu 2+ Crystalline hydrates and Ni-containing 2+ The crystalline hydrate of the metal was added to deionized water to prepare an aqueous solution containing metal ions; d. Add the melamine-sodium alginate-glucose ternary composite water-based viscous colloid to the aqueous solution containing metal ions obtained in step c, and let it stand and stir at room temperature for 6-8 hours to obtain hydrogel beads with a 3D network porous structure, containing Cu metal ions. 2+ Ni 2+ Distributed within the network of the aforementioned hydrogel beads; e. Wash and freeze-dry the hydrogel beads obtained in step d to obtain aerogel beads; carbonize the aerogel beads under a nitrogen atmosphere. The carbonization temperature is divided into three stages: the first stage is 300℃ < T1 ≤ 500℃, the heating rate is 5°C / min, and the carbonization time is 40min; the second stage is 500℃ < T2 ≤ 700℃, the heating rate is 20°C / min, and the carbonization time is 10min; the third stage is 700℃ < T3 ≤ 900℃, the heating rate is 5°C / min, and the carbonization time is 40min; thus, the adsorbent is obtained. The conditions for low-temperature removal of COS from natural gas to resist competitive CO2 adsorption are as follows: Temperature 40℃, air velocity 70000h -1 The simulated gas composition, by volume percentage, is: 25% CO, 40ppm COS, 20% CO2, and balanced nitrogen.

[0008] The above-mentioned method for preparing a low-temperature adsorbent for COS removal from natural gas with anti-CO2 competitive adsorption, in step c, contains Cu 2+ The crystalline hydrate is copper nitrate trihydrate.

[0009] The above-mentioned method for preparing an adsorbent for low-temperature removal of COS from natural gas with resistance to CO2 competitive adsorption, in step c, contains Ni 2+ The crystalline hydrate is nickel nitrate hexahydrate.

[0010] The above-mentioned method for preparing a low-temperature adsorbent for COS removal from natural gas with anti-CO2 competitive adsorption, in step c, contains Cu 2+ The mass-to-volume ratio of the crystalline hydrate to deionized water is 1–2:165 g / mL; containing Ni2+ The mass-to-volume ratio of the crystalline hydrate to deionized water is 0.3–0.6:165 g / mL.

[0011] In the above-mentioned method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2, in step a, melamine and sodium alginate are dissolved at room temperature for 12 hours, and the stirring speed is 300-500 r / min.

[0012] In the above-mentioned method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2, in step d, a constant flow pump is used to uniformly add the melamine-sodium alginate-glucose ternary composite water-based viscous colloid to the aqueous solution containing metal ions obtained in step c.

[0013] In the above-mentioned method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2, in step e, the hydrogel beads are washed 6 times with deionized water, and the water is changed every 2 minutes during washing; the beads are then freeze-dried in a vacuum freeze dryer for 10-13 hours.

[0014] The above-mentioned method for preparing a low-temperature adsorbent for CO2 competitive adsorption in natural gas involves melamine generating weak and medium-alkaline sites to inhibit CO2 competitive adsorption; in step e, during the carbonization process, the Ni-containing gas condensate beads in the first stage... 2+ The crystallization hydrate forms nickel oxide, containing Cu 2+ In the first stage, the crystalline hydrate forms copper oxide; in the second stage, the copper oxide is reduced; and in the third stage, the nickel oxide is reduced to elemental nickel.

[0015] Another object of the present invention is to provide an adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2, which is prepared by the above-described preparation method.

[0016] The aforementioned low-temperature adsorbent for COS removal from natural gas, which resists competitive CO2 adsorption, has a BET specific surface area ≥ 220 m² / g. -1 The average pore size is ≥5.5nm, and the proportion of macropores is ≥15%.

[0017] The preparation mechanism of the adsorbent of this invention is as follows: Using sodium alginate as a template and carbon source, and melamine as a nitrogen source, the melamine-sodium alginate-glucose ternary composite water-based viscous colloid is added to a copper nitrate and nickel nitrate bimetallic solution. The metal ions rapidly chelate onto the sodium alginate, forming spherical, stable hydrogel microspheres. After drying and high-temperature pyrolysis, melamine generates pyridine nitrogen and pyrrole nitrogen, among other basic active sites, in situ, enhancing the selective adsorption of COS. The carbonization process is divided into three stages: the first stage generates nickel oxide; the second stage reduces copper oxide, thus shortening its residence time; and the third stage reduces nickel oxide to elemental nickel, which does not react with CO2, endowing the material with resistance to CO2 interference. The bimetallic structure and carbon framework synergistically stabilize the pore structure, ultimately yielding an adsorbent with high specific surface area, high activity, and resistance to CO2.

[0018] Compared with the prior art, the present invention brings the following beneficial technical effects: (1) This invention proposes a method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2. In terms of raw material selection, sodium alginate is used as the spherical framework, melamine provides abundant nitrogen source and pyridine nitrogen sites (which also resist competitive adsorption of carbon dioxide during subsequent carbonization), and copper nitrate and nickel nitrate bimetallic salts are used. The raw materials are inexpensive, readily available, green, and safe. Melamine can significantly increase the content of pyridine nitrogen active sites, enhancing the selective removal of COS. Under the condition of glucose heating and electron release, nickel oxide is reduced to elemental nickel, which does not react with CO2, achieving stable desulfurization resistant to CO2 interference. The pores do not collapse after pyrolysis, resulting in higher stability. The material possesses high activity, high selectivity, and high stability, enabling deep removal of COS from natural gas. The pyrolysis of nickel oxide to generate elemental nickel endows the material with excellent resistance to CO2 poisoning from the raw material level. Bimetallic synergistic crosslinking significantly improves the structural stability and desulfurization activity of the material.

[0019] (2) In terms of preparation method: The melamine-sodium alginate-glucose ternary composite water-based viscous colloid is added at a constant flow rate to an aqueous solution containing metal ions using a constant flow pump. This allows for the control of obtaining droplets of uniform size, which has the advantages of good molding consistency and high stability. The resulting hydrogel beads have a larger specific surface area and better mass transfer. One-step ion crosslinking molding is carried out under mild conditions and with strong controllability, solving the problems of uneven molding, low activity, and poor stability of existing methods.

[0020] (3) The adsorbent prepared by this invention is suitable for an environment with a temperature of 40°C. This solves the technical problem of the inability to deeply remove COS at low temperatures in the prior art. More importantly, the adsorbent prepared by this invention can remove carbonyl sulfide (COS) at low temperatures and also possesses excellent anti-carbon dioxide competitive adsorption capacity. Experimental verification shows that the removal efficiency of the CO2-resistant adsorbent of this invention can reach 100% within 240 minutes and over 90% within 360 minutes. Furthermore, after three cycles at a regeneration temperature of 90°C, it still retains an efficiency of 85.2% for fresh samples. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings: Figure 1 The diagram shows the COS removal efficiency of the adsorbents prepared in Examples 1-4 of this invention.

[0022] Figure 2 The diagram shows the COS removal efficiency of the adsorbents prepared in Comparative Examples 1-6 of this invention.

[0023] Figure 3 This is an appearance diagram of the hydrogel beads prepared according to the present invention.

[0024] Figure 4 This is an appearance diagram of the adsorbent prepared according to the present invention. Detailed Implementation

[0025] This invention proposes an adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2, and its preparation method. To make the advantages and technical solutions of this invention clearer and more explicit, the invention will be further described below with reference to specific embodiments.

[0026] All the raw materials required in this invention can be purchased through commercial channels.

[0027] The specific method for low-temperature COS removal using the anti-CO2 competitive adsorbent prepared by this invention is as follows: Detection method: A fixed-bed reactor was used, and the concentration of COS at the outlet was detected by gas chromatograph (GC-9720P1us).

[0028] Experimental conditions: air velocity 70,000 h⁻¹ -1 The temperature was 40°C. The simulated gas composition, by volume percentage, was: 25% CO, 40 ppm COS, 20% CO2, and balanced nitrogen. Water was supplied using a saturator system, and the water content was expressed as relative humidity (RH). A fixed-bed heating system simulated a natural gas environment, and a mass flow controller was used to control the total flow rate at 100 mL / min.

[0029] The main technical concept of this invention is as follows: This invention addresses the problems of poor CO2 resistance, insufficient active sites, uneven molding, and low removal efficiency at low temperatures in COS removal from natural gas. Sodium alginate is used as the spheroidizing substrate, and melamine is used as a nitrogen-rich precursor to provide pyridine nitrogen active sites (which also resist competitive adsorption of carbon dioxide during subsequent carbonization). Nickel nitrate is added after chelation with copper nitrate, and reduced to elemental nickel after pyrolysis to achieve resistance to CO2 interference. Hydrogel microspheres with uniform particle size and large specific surface area are obtained by constant-flow pump dripping, improving mass transfer and desulfurization efficiency. After cross-linking, drying, and pyrolysis, a highly stable, highly selective, and CO2-resistant high-efficiency COS removal material is obtained. The technical effects achieved by this invention are: uniform particle size of the hydrogel beads; high specific surface area and high pyridine nitrogen content in the prepared adsorbent; and significantly improved resistance to carbon dioxide interference.

[0030] Example 1: A method for preparing a low-temperature adsorbent for COS removal from natural gas that resists CO2 competitive adsorption includes the following steps: Step 1: Dissolve 0.5g of melamine and 0.5g of sodium alginate in 100ml of deionized water at room temperature for 12 hours to obtain a colloidal dispersion system; Step 2: Dissolve 1g of glucose in the colloidal dispersion system and continue dissolving to obtain a melamine-sodium alginate-glucose ternary composite water-based viscous colloid. Step 3: Dissolve 1g of copper nitrate trihydrate and 0.3g of nickel nitrate hexahydrate in 165ml of deionized water to obtain an aqueous solution containing metal ions; Step 4: Place the melamine-sodium alginate-glucose ternary composite water-based viscous colloid in a constant flow pump and squeeze it dropwise into an aqueous solution containing metal ions. Let it stand and stir at room temperature for 6-8 hours to obtain hydrogel beads with a 3D network porous structure. The metal ions Cu 2+ Ni 2+ Distributed within the network of the aforementioned hydrogel beads.

[0031] Step 5: Wash the hydrogel beads with deionized water 6 times, changing the water every 2 minutes, and then freeze-dry them in a vacuum freeze dryer for 10 hours to obtain aerogel beads; carbonize the aerogel beads in a nitrogen atmosphere for one hour, with a heating rate of 5°C / min, until 300°C is reached, and continue carbonizing for 40 minutes until T1=500 is reached, thus obtaining the product.

[0032] The adsorbent prepared in this embodiment for low-temperature COS removal from natural gas, which resists CO2 competitive adsorption, was tested at low temperature with a space velocity of 70,000 h⁻¹. -1The temperature was 40℃. The simulated gas composition was: 25% CO, 40ppm COS, 20% CO2, and balanced nitrogen. A saturator system was used to supply water, and the water content was expressed as relative humidity (RH). In this invention, RH was always taken as 20%. A water bath heating method was used to simulate a natural gas environment. A mass flow controller was used to control the total flow rate at 100mL / min. The results showed that within 120min, the CO2-resistant competitive adsorbent prepared in this embodiment maintained a COS removal rate of over 90%, and within 240min, the COS removal rate remained above 80%.

[0033] Example 2: A low-temperature COS removal adsorbent for natural gas that resists CO2 competitive adsorption and its preparation method include the following steps: Step 1: Dissolve 0.7g of melamine and 0.8g of sodium alginate in 100ml of deionized water for 12 hours to obtain a colloidal dispersion system; Step 2: Dissolve 1.5g of glucose in the colloidal dispersion system to obtain a melamine-sodium alginate-glucose ternary composite water-based viscous colloid. Step 3: Dissolve 1.3g of copper nitrate trihydrate and 0.4g of nickel nitrate hexahydrate in 165ml of deionized water to obtain an aqueous solution containing metal ions; Step 4: Place the melamine-sodium alginate-glucose ternary composite water-based viscous colloid in a constant flow pump and squeeze it dropwise into an aqueous solution containing metal ions. Let it stand and stir at room temperature for 6-8 hours to obtain hydrogel beads with a 3D network porous structure. The metal ions Cu 2+ Ni 2+ Distributed within the network of the aforementioned hydrogel beads.

[0034] Step 5: Wash the hydrogel beads with deionized water 6 times, changing the water every 2 minutes, and then freeze-dry them in a vacuum freeze dryer for 11 hours to obtain aerogel beads. Carbonize the aerogel beads in a nitrogen atmosphere. The carbonization is divided into two stages. The first stage is 300℃<T1≤500℃, with a heating rate of 5°C / min and a carbonization time of 40 minutes. Then, heat the temperature to 700℃ and carbonize for 10 minutes at a heating rate of 20°C / min to obtain the final product.

[0035] The anti-CO2 competitive adsorbent prepared in this embodiment was tested at low temperature, using the same method as in Example 1. The results showed that the removal rate of COS by the anti-CO2 competitive adsorbent in this embodiment was over 90% within 360 min, and remained above 80% within 510 min.

[0036] Example 3: A low-temperature COS removal adsorbent for natural gas that resists CO2 competitive adsorption and its preparation method include the following steps: Step 1: Dissolve 0.9g of melamine and 1g of sodium alginate in 100ml of deionized water for 12 hours to obtain a colloidal dispersion system; Step 2: Dissolve 2g of glucose in the colloidal dispersion system to obtain a melamine-sodium alginate-glucose ternary composite water-based viscous colloid. Step 3: Dissolve 1.5g of copper nitrate trihydrate and 0.5g of nickel nitrate hexahydrate in 165ml of deionized water to obtain an aqueous solution containing metal ions; Step 4: Place the melamine-sodium alginate-glucose ternary composite water-based viscous colloid in a constant flow pump and drip it into an aqueous solution containing metal ions. Let it stand and stir at room temperature for 6-8 hours to obtain hydrogel beads with a 3D network porous structure. The metal ions Cu 2+ Ni 2+ Distributed within the network of the hydrogel beads. An image of the hydrogel beads is shown below. Figure 3 As shown.

[0037] Step 5: Wash the hydrogel beads 6 times with deionized water, changing the water every 2 minutes. Then, freeze-dry them in a vacuum freeze dryer for 12 hours to obtain aerogel beads. Carbonize the aerogel beads under a nitrogen atmosphere in two stages: the first stage is 300℃ < T1 ≤ 500℃, with a heating rate of 5°C / min and a carbonization time of 40 minutes; the second stage is 500℃ < T1 ≤ 700℃, with a heating rate of 20°C / min and a carbonization time of 10 minutes; finally, heat to 850℃ and carbonize for 30 minutes at a heating rate of 5°C / min to obtain the final product. The appearance of the adsorbent is shown in the image below. Figure 4 As shown.

[0038] The anti-CO2 competitive adsorbent prepared in this embodiment was tested at low temperature, using the same method as in Example 1. The results showed that the removal rate of COS by the anti-CO2 competitive adsorbent in this embodiment was over 90% within 420 min, and remained above 80% within 540 min.

[0039] Example 4: A low-temperature COS removal adsorbent for natural gas that resists CO2 competitive adsorption and its preparation method include the following steps: Step 1: Dissolve 1g of melamine and 1g of sodium alginate in 100ml of deionized water for 12 hours to obtain a colloidal dispersion system; Step 2: Dissolve 2.5g of glucose in the colloidal dispersion system to obtain a melamine-sodium alginate-glucose ternary composite water-based viscous colloid.

[0040] Step 3: Dissolve 2g of copper nitrate trihydrate and 0.6g of nickel nitrate hexahydrate in 165ml of deionized water to obtain an aqueous solution containing metal ions.

[0041] Step 4: Place the melamine-sodium alginate-glucose ternary composite water-based viscous colloid in a constant flow pump and drip it into an aqueous solution containing metal ions. Let it stand and stir at room temperature for 6-8 hours to obtain hydrogel beads with a 3D network porous structure. The metal ions Cu 2+ Ni 2+ Distributed within the network of the aforementioned hydrogel beads.

[0042] Step 5: Wash the aerosol beads 6 times with deionized water, changing the water every 2 minutes, then freeze-dry them in a vacuum freeze dryer for 13 hours to obtain aerosol beads. Carbonize the aerosol beads under a nitrogen atmosphere in three stages: Stage 1: 300℃ < T1 ≤ 500℃, heating rate 5°C / min, carbonization time 40 min; Stage 2: 500℃ < T2 ≤ 700℃, heating rate 20°C / min, carbonization time 10 min; Stage 3: 900℃, heating rate 5°C / min, carbonization time 40 min; thus, the adsorbent is obtained. The anti-CO2 competitive adsorbent prepared in this embodiment was tested at low temperature using the same method as in Example 1. The results showed that the carbonyl sulfur removal rate was over 90% within 190 min, and the desulfurization efficiency remained above 80% within 280 min.

[0043] Comparative Example 1: The difference from Example 3 is as follows: In step one, 0.9g of ethylenediamine and 1g of sodium alginate were dissolved in 100ml of deionized water for 12 hours to obtain a colloidal dispersion system. The rest is the same as in Example 3.

[0044] The results showed that the COS removal rate of this comparative CO2-resistant competitive adsorbent remained above 90% within 60 minutes, and remained above 80% within 90 minutes.

[0045] Comparative Example 2: The difference from Example 3 is as follows: In step one, 0.9g of urea and 1g of sodium alginate are dissolved in 100ml of deionized water for 12 hours to obtain a colloidal dispersion system. The rest is the same as in Example 3.

[0046] The results showed that the COS removal rate of this comparative CO2-resistant competitive adsorbent was over 90% within 180 min, and remained above 80% within 210 min.

[0047] Comparative Example 3: The difference from Example 3 is that in step three, 2g of copper nitrate trihydrate is dissolved in 165ml of deionized water to obtain an aqueous solution containing metal ions. The rest is the same as in Example 3.

[0048] The results showed that the COS removal rate of this comparative CO2-resistant competitive adsorbent remained above 90% within 80 minutes, and remained above 80% within 120 minutes.

[0049] Comparative Example 4: The difference from Example 3 is that in step three, 1.5g of copper nitrate trihydrate and 0.5g of tin nitrate trihydrate are dissolved in 165ml of deionized water to obtain an aqueous solution containing metal ions; the rest is the same as in Example 3.

[0050] The results showed that the COS removal rate of this comparative CO2-resistant competitive adsorbent remained above 90% within 120 min, and remained above 80% within 140 min.

[0051] Comparative Example 5: The difference from Example 3 is that glucose is not added in step two.

[0052] Step 1: Dissolve 0.9g of melamine and 1g of sodium alginate in 100ml of deionized water for 12 hours to obtain a colloidal dispersion system; Step 2: Dissolve 1.5g of copper nitrate trihydrate and 0.5g of nickel nitrate hexahydrate in 165ml of deionized water to obtain an aqueous solution containing metal ions; Step 3: Place the colloidal dispersion system in a constant flow pump and drip it into an aqueous solution containing metal ions. Let it stand and stir at room temperature for 6-8 hours to obtain hydrogel beads with a 3D network porous structure. The metal ions Cu 2+ Ni 2+ Distributed within the network of the aforementioned hydrogel beads.

[0053] Step 4: Wash the hydrogel beads 6 times with deionized water, changing the water every 2 minutes, and then freeze-dry them in a vacuum freeze dryer for 12 hours to obtain aerogel beads. Carbonize the aerogel beads under a nitrogen atmosphere in three stages: the first stage is 300℃ < T1 ≤ 500℃, with a heating rate of 5°C / min and a carbonization time of 40 minutes; the second stage is 500℃ < T1 ≤ 700℃, with a heating rate of 20°C / min and a carbonization time of 10 minutes; then heat to 850℃ and carbonize for 30 minutes at a heating rate of 5°C / min to obtain the final product.

[0054] The results showed that the COS removal rate of this comparative CO2-resistant competitive adsorbent was over 90% within 200 min, and remained above 80% within 300 min.

[0055] Comparative Example 6: The difference from Example 3 is that a constant flow pump was not used in step four; instead, a separatory funnel was used.

[0056] Step 1: Dissolve 0.9g of melamine and 1g of sodium alginate in 100ml of deionized water for 12 hours to obtain a colloidal dispersion system; Step 2: Dissolve 2g of glucose in the colloidal dispersion system to obtain a melamine-sodium alginate-glucose ternary composite water-based viscous colloid. Step 3: Dissolve 1.5g of copper nitrate trihydrate and 0.5g of nickel nitrate hexahydrate in 165ml of deionized water to obtain an aqueous solution containing metal ions; Step 4: Place the melamine-sodium alginate-glucose ternary composite water-based viscous colloid in a separatory funnel and squeeze it dropwise into an aqueous solution containing metal ions. Let it stand and stir at room temperature for 6-8 hours to obtain hydrogel beads with a 3D network porous structure. The metal ions Cu 2+ Ni 2+ Distributed within the network of the aforementioned hydrogel beads.

[0057] Step 5: Wash the hydrogel beads 6 times with deionized water, changing the water every 2 minutes, and then freeze-dry them in a vacuum freeze dryer for 12 hours to obtain aerogel beads. Carbonize the aerogel beads under a nitrogen atmosphere in three stages: the first stage is 300℃ < T1 ≤ 500℃, with a heating rate of 5°C / min and a carbonization time of 40 minutes; the second stage is 500℃ < T1 ≤ 700℃, with a heating rate of 20°C / min and a carbonization time of 10 minutes; then heat to 850℃ and carbonize for 30 minutes at a heating rate of 5°C / min to obtain the final product.

[0058] The results showed that the COS removal rate of this comparative CO2-resistant competitive adsorbent remained above 90% within 150 min, and above 80% within 200 min.

[0059] Figure 1 The diagram shows the COS removal efficiency of the adsorbents prepared in Examples 1-4 of this invention. Figure 2This is a COS removal efficiency diagram of the adsorbents prepared in Comparative Examples 1-6 of this invention. As shown in the examples, the optimal preparation conditions of this invention are: sodium alginate:melamine mass = 1:0.9, nickel nitrate hexahydrate:copper nitrate trihydrate mass = 0.5:1.5, combined with a constant flow pump dropping process. Under these conditions, the components synergistically enhance each other, resulting in a high degree of cross-linking and abundant active sites in the material, significantly outperforming the other examples. When the sodium alginate:melamine mass ratio is 1:0.9, sodium alginate can form cross-links with melamine, stabilizing the three-dimensional gel network while providing sufficient nitrogen active sites to effectively anchor and disperse metal ions. Cu² + To ensure gel formation and structural stability, constant-flow pump-assisted, uniform dripping avoids localized metal ion aggregation, guaranteeing uniform and stable material properties. Replacing melamine with urea and ethylenediamine significantly degrades performance. Urea has weak cross-linking ability and few active sites. Ethylenediamine can only form simple linear cross-links and cannot construct a three-dimensional network structure. The nitrogen sites formed by urea and ethylenediamine doping have low activity, making it difficult to coordinate with metal ions, resulting in overall performance far lower than the melamine system. Tin ions replacing nickel ions have extremely poor compatibility and weak coordination with the matrix and nitrogen sites, failing to construct a highly active metal-nitrogen-oxygen structure and introducing structural defects. Glucose serves as a supplementary carbon source for reduction; direct dripping without a constant-flow pump easily leads to excessively high local metal salt concentrations, causing aggregation and precipitation, and disrupting the regular gel structure.

[0060] Any parts not mentioned in this invention can be achieved by referring to existing technologies.

[0061] It should be noted that those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed by this application.

Claims

1. A method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2, characterized in that, The steps are as follows: a. Melamine and sodium alginate are dissolved in deionized water at room temperature to obtain a colloidal dispersion system; the mass-to-volume ratio of melamine, sodium alginate and deionized water is 0.5-1.0 g: 100 mL. b. Weigh 1-2.5g of glucose and dissolve it in the colloidal dispersion system to obtain a melamine-sodium alginate-glucose ternary composite water-based viscous colloid. c. Containing Cu 2+ Crystalline hydrates and Ni-containing 2+ The crystalline hydrate of the metal was added to deionized water to prepare an aqueous solution containing metal ions; d. Add the melamine-sodium alginate-glucose ternary composite water-based viscous colloid to the aqueous solution containing metal ions obtained in step c, and let it stand and stir at room temperature for 6-8 hours to obtain hydrogel beads with a 3D network porous structure, containing Cu metal ions. 2+ Ni 2+ Distributed within the network of the aforementioned hydrogel beads; e. Wash and freeze-dry the hydrogel beads obtained in step d to obtain aerogel beads; carbonize the aerogel beads under a nitrogen atmosphere. The carbonization temperature is divided into three stages: the first stage is 300℃ < T1 ≤ 500℃, the heating rate is 5°C / min, and the carbonization time is 40min; the second stage is 500℃ < T2 ≤ 700℃, the heating rate is 20°C / min, and the carbonization time is 10min; the third stage is 700℃ < T3 ≤ 900℃, the heating rate is 5°C / min, and the carbonization time is 40min; thus, the adsorbent is obtained. The conditions for low-temperature removal of COS from natural gas to resist competitive CO2 adsorption are as follows: Temperature 40℃, air velocity 70000h -1 The simulated gas composition, by volume percentage, is: 25% CO, 40ppm COS, 20% CO2, and balanced nitrogen.

2. The method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists CO2 competitive adsorption according to claim 1, characterized in that: In step c, Cu 2+ The crystalline hydrate is copper nitrate trihydrate.

3. The method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists CO2 competitive adsorption according to claim 1, characterized in that: In step c, Ni 2+ The crystalline hydrate is nickel nitrate hexahydrate.

4. The method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists CO2 competitive adsorption according to claim 1, characterized in that: In step c, Cu 2+ The mass-to-volume ratio of the crystalline hydrate to deionized water is 1–2:165 g / mL; containing Ni 2+ The mass-to-volume ratio of the crystalline hydrate to deionized water is 0.3–0.6:165 g / mL.

5. The method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists CO2 competitive adsorption according to claim 1, characterized in that: In step a, melamine and sodium alginate are dissolved at room temperature for 12 hours with a stirring speed of 300-500 r / min.

6. The method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists CO2 competitive adsorption according to claim 1, characterized in that: In step d, the melamine-sodium alginate-glucose ternary composite water-based viscous colloid is added at a constant rate to the aqueous solution containing metal ions obtained in step c using a constant flow pump.

7. The method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists CO2 competitive adsorption according to claim 1, characterized in that: In step e, the hydrogel beads are washed 6 times with deionized water, with the water changed every 2 minutes during washing; then they are freeze-dried in a vacuum freeze dryer for 10–13 hours.

8. The method for preparing an adsorbent for low-temperature removal of COS from natural gas that resists CO2 competitive adsorption according to claim 1, characterized in that: Melamine generates weak and medium-basic sites to inhibit competitive adsorption of CO2; in step e, during the carbonization process, the Ni-containing condensate beads in the first stage... 2+ The crystallization hydrate forms nickel oxide, containing Cu 2+ In the first stage, the crystalline hydrate forms copper oxide; in the second stage, the copper oxide is reduced; and in the third stage, the nickel oxide is reduced to elemental nickel.

9. An adsorbent for low-temperature removal of COS from natural gas that resists competitive adsorption of CO2, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

10. The adsorbent for low-temperature removal of COS from natural gas with resistance to CO2 competitive adsorption as described in claim 9, characterized in that: The adsorbent has a BET specific surface area ≥ 220 m² / g -1 The average pore size is ≥5.5nm, and the proportion of macropores is ≥15%.

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