A dual-function desulfurizing agent for acidic gases and its preparation method

Abstract

This invention belongs to the field of catalyst technology, specifically relating to a bifunctional desulfurizing agent for acidic gases and its preparation method. The bifunctional desulfurizing agent for acidic gases includes an iron-based matrix support and active ingredients; the iron-based matrix support is Fe2O3 and M... x O y and M a (SO4) b A mixture, wherein M is selected from Group IIA and IIIA metals, preferably at least one of Ca, Mg, Ba, B, Al, Ga, and In; the active ingredient is A. c O d A is selected from at least one of Na, K, Li, and Cs. This desulfurizing agent can be used to remove hydrogen sulfide and small-molecule organic sulfides from acidic gases such as blast furnace gas and carbon dioxide, and has the advantages of large sulfur capacity and high desulfurization precision.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to an acidic gas bifunctional desulfurizer and its preparation method. Background Technology

[0002] The extensive use of fossil resources such as coal, oil, and natural gas has brought unprecedented prosperity to human society. However, this has also been accompanied by massive carbon dioxide emissions, exacerbating global warming and placing enormous pressure on the ecological environment. Therefore, reducing and lowering CO2 emissions is urgently needed. One approach is to generate electricity using renewable energy sources (such as wind and solar power), then electrolyze water to produce green hydrogen, which can be used to reduce CO2 and convert it into high-value-added chemicals and fuels. This can not only effectively reduce greenhouse gas emissions but also promote sustainable economic and social development. In recent years, the conversion of CO2 into high-value-added chemicals and fuels such as methanol (green alcohol), ammonia (green ammonia), and natural gas (green LNG) has attracted widespread attention, and significant progress has been made in its industrialization.

[0003] However, industrial CO2 emissions contain trace amounts of sulfides, such as hydrogen sulfide (H2S), carbonyl sulfide (COS), and carbon disulfide (CS2). If these sulfides cannot be removed to below 0.1 ppm, they can easily poison and deactivate downstream catalysts, such as copper-based catalysts for methanol synthesis, iron-based catalysts for ammonia synthesis, and nickel-based catalysts for natural gas synthesis. Industrially, COS and CS2 are typically converted to H2S via catalytic hydrogenation, followed by the removal of H2S using zinc oxide, activated carbon, or iron oxide desulfurizing agents. However, carbon dioxide does not contain hydrogen (H2), and adding it would inevitably increase operating costs. Furthermore, the hydrogenation reaction requires high temperatures, resulting in high energy consumption. Another industrial solution is to use organic sulfur hydrolysis catalysts to convert COS and CS2 to H2S, followed by the removal of H2S using zinc oxide, activated carbon, or iron oxide desulfurizing agents. The principle of the hydrolysis reaction is as follows:

[0004] COS + H2O = H2S + CO2 (1)

[0005] CS2 + H2O = 2H2S + CO2 (2)

[0006] For conventional gases, the CO2 content is usually below 5% (e.g., coke oven gas). The conversion rate of the above reaction proceeding to the right is relatively high. If a combination of desulfurizing agent-hydrolyzing agent-desulfurizing agent is used, the total sulfur content can be controlled at a low level. However, the removal of trace sulfides, especially trace organic sulfides, from pure CO2 or feed gas with high CO2 content becomes very difficult, mainly because the reverse reaction of the above organic sulfur hydrolysis reaction becomes dominant.

[0007] H2S + CO2 = COS + H2O (3)

[0008] 2H₂S + CO₂ = CS₂ + H₂O (4)

[0009] Studies have shown that the reaction of hydrogen sulfide with carbon dioxide to form COS and CS2 mainly occurs through the reaction of nascent single-atom sulfur on the surface of the desulfurizing agent with CO2. For example, the removal of H2S by iron oxide desulfurizing agents and activated carbon desulfurizing agents mainly occurs through the following reactions:

[0010] H₂S + 1 / 2O₂ = 1 / XS x +H2O (5)

[0011] If the organic sulfur hydrolysis reaction and the sulfur hydroxide oxidation reaction can be concentrated on a single desulfurizing agent, the effects of reactions (3) and (4) can be effectively avoided.

[0012] Chinese invention patent application CN 113244752 A discloses a desulfurizing agent composed of carbon-based iron materials, alkaline earth metal oxides, alkali metal oxides, zinc oxide, and titanium oxide. It is claimed to have a high H2S removal capacity and some removal effect on organic sulfur, but specific data on its performance with organic sulfur are not provided. Furthermore, the reaction evaluation conditions only list a hydrogen sulfide content of 0.5%, without mentioning the composition of organic sulfur and raw material gas. Chinese invention patent application CN 121060536 A discloses a bifunctional desulfurizing agent. First, a mixture of alumina, alkali metal (one or more of K, Ca, Na, Mg) compounds, and a binder is prepared. Then, the mixture is spherically rolled, dried, and calcined to obtain a catalyst support. Next, a solution of one or more transition metal compounds such as Co, Cu, Ni, Mn, and Fe is loaded onto the catalyst support. After drying and calcination, a room-temperature bifunctional desulfurizing agent is obtained. Evaluation conditions: H2S 175ppm, COS 20ppm, methanethiol 5ppm, balance N2. This desulfurizer has a sulfur capacity of 10% for H2S, while the sulfur capacity for organic sulfur is between 5% and 10%. Chinese invention patent application CN 109045993 B discloses a bifunctional desulfurizer, which is obtained by co-precipitation reaction of ferrous salt solution and sodium aluminate to obtain a mixture containing FeOOH and Al(OH)3. This mixture is then extruded using bentonite or polyvinyl alcohol as a binder and dried at low temperature to obtain a bifunctional room-temperature desulfurizer. Syngas (CO+H2) is used as the base gas, but the specific composition is not specified. It contains 107ppm H2S and 89ppm COS, and is produced at 80℃ and a space velocity of 1000... -1Experiments were conducted under a pressure of 0.2 MPa, with outlet H2S at 0.12 ppm and COS at 25 ppm, indicating good removal efficiency for hydrogen sulfide and low hydrolysis rate of organic sulfur. Chinese invention patent application CN 120618449 B discloses a bifunctional desulfurizing agent. It uses a mixture of CuO, ZnO, and Al2O3 and a second binder as the inner core, and FeOOH and a first binder as the outer layer, obtained through a double-layer extrusion mill. This desulfurizing agent can simultaneously remove hydrogen sulfide and carbonyl sulfur under aerobic conditions. Evaluation conditions: H2S 1000 ppm, COS 100 ppm, CH3SH 10 ppm, O2 1%, balance N2; space velocity 500 h⁻¹. -1 The temperature was 150℃, and the pressure was normal. The sulfur capacity was between 10% and 20%. The patent did not specify the desulfurization precision, and the base gas used was nitrogen.

[0013] The above-mentioned invention patents are all used under conditions of no or low CO2 (such as CN 109045993 B), and do not consider the influence of CO2 on the hydrolysis of organic sulfur. However, research has shown that under a CO2 atmosphere, the hydrolysis reaction of organic sulfur is significantly inhibited and its reverse reaction, i.e., the formation of organic sulfur, is favored. Therefore, it is particularly important to develop a bifunctional desulfurizer suitable for acidic gases, i.e., gases with a CO2 content ≥ 50%. Summary of the Invention

[0014] To address the shortcomings of the prior art, this invention provides a bifunctional desulfurizing agent for acidic gases and its preparation method. This bifunctional desulfurizing agent can effectively reduce the inhibition of organic sulfur hydrolysis by CO2, making it suitable for use under high CO2 content conditions.

[0015] The specific plan is as follows:

[0016] A dual-function desulfurizing agent for acidic gases includes an iron-based matrix carrier and active ingredients; the iron-based matrix carrier is Fe2O3 and M. x O y and M a (SO4) b A mixture, wherein M is selected from at least one metal from Group IIA and IIIA, preferably Ca, Mg, Ba, B, Al, Ga, or In; the active ingredient is A. c O d A is selected from at least one of Na, K, Li, and Cs.

[0017] Furthermore, the active ingredient also includes a polyol; preferably, the polyol is selected from at least one of ethylene glycol, diethylene glycol, glycerol, diglycerol, polyethylene glycol with a molecular weight of 200-600, glucose, fructose, sucrose, and lactose.

[0018] Furthermore, in the acidic gas dual-function desulfurizing agent, A, by mass parts, c O d It accounts for 2wt%~20wt% of the desulfurizing agent; polyol accounts for 0wt%~10wt% of the desulfurizing agent; and iron-based parent carrier accounts for 70wt%~98wt% of the desulfurizing agent.

[0019] Furthermore, in the iron-based parent carrier, Fe2O3 accounts for 20wt%~60wt% of the carrier mass by weight; M x O y 20wt%~60wt% of the carrier mass; M a (SO4) b It accounts for 20wt% to 60wt% of the carrier mass.

[0020] A method for preparing an acidic gas bifunctional desulfurizer includes the following steps:

[0021] S1 utilizes iron salt, salt containing M, and water to knead and shape to obtain an iron-based matrix carrier; wherein, at least one of the raw materials, iron salt and salt containing M, contains sulfate ions;

[0022] S2. Prepare a mixed aqueous solution using a salt containing A; impregnate the iron-based parent carrier obtained in step S1 to obtain the bifunctional desulfurizer.

[0023] Furthermore, in step S1, the iron salt is selected from at least one of ferrous sulfate, ferric hydroxide, and active iron oxide γ-Fe2O3; the salt containing M is selected from at least one of hydroxide, oxide, and sulfate.

[0024] Preferably, step S1 further includes drying; the drying temperature is 20~100℃, and the drying time is 2~20h.

[0025] Furthermore, in step S2, the salt containing A is at least one of oxides, hydroxides, carbonates, and basic carbonates, preferably Na2O, NaOH, Na2CO3, NaHCO3, K2O, KOH, K2CO3, or KHCO3.

[0026] Furthermore, in step S2, the mixed aqueous solution also includes a polyol.

[0027] Preferably, step S2 further includes drying; the drying temperature is 30~200℃, and the drying time is 1~20h.

[0028] The beneficial effects are as follows:

[0029] Since the reaction of hydrogen sulfide with carbon dioxide to generate COS and CS2 mainly occurs through the reaction of nascent single-atom sulfur on the surface of the desulfurizer with CO2, this invention accelerates the aggregation of nascent single-atom sulfur on the surface of the desulfurizer into sulfur particles (S) by adding polyols. x This reduces the probability of single-atom sulfur reacting with CO2. Secondly, by impregnating the carrier with a mixture of alkaline substances and polyols, a local aggregation effect on water molecules can be formed, reducing the concentration of CO2 on the surface and effectively promoting the hydrolysis reaction of organic sulfur. Simultaneously, these two components react with Fe2O3 and M in the iron-based parent carrier. x O y (e.g., CaO) at the molecular level can accelerate the oxidation reaction of H2S, thereby improving desulfurization efficiency. The combined result of the triple effect is that it increases both sulfur capacity and improves the purification degree of organic sulfur. This desulfurizing agent can be used to remove hydrogen sulfide and small molecule organic sulfur compounds from acidic gases such as blast furnace gas and carbon dioxide, and has the advantages of large sulfur capacity and high desulfurization precision. Detailed Implementation

[0030] The embodiments of the present invention will be described in further detail below. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention. Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0031] Example 1

[0032] Weigh 50g of ferrous sulfate (FeSO4·7H2O) and 50g of calcium hydroxide (Ca(OH)2), mix the two materials evenly, add 30mL of deionized water and knead for 10min, extrude into strips using a 3-4mm perforated plate extruder, and dry at 30℃ for 15h to obtain the iron-based matrix carrier; weigh 10g of sodium carbonate (Na2CO3) and dissolve in 15mL of deionized water, then add 5g of glycerol (C3H8O3) and stir evenly to form a mixed solution; add 66.6g of the iron-based matrix carrier to 19mL of the mixed solution and impregnate for 30min, then remove and dry at 60℃ for 8h to obtain the acidic gas bifunctional desulfurizer.

[0033] The acid gas dual-function desulfurizer contains 18.5 wt% Fe2O3, 35.8 wt% CaO, 31.7 wt% CaSO4, 7.56 wt% Na2O, and 6.44 wt% glycerol.

[0034] Example 2

[0035] Weigh 50g of ferrous sulfate (FeSO4·7H2O) and 30g of calcium hydroxide (Ca(OH)2), mix the two materials thoroughly, add 20mL of deionized water and knead for 10min, then extrude into strips using a 3-4mm perforated sheet extruder and dry at 40℃ for 10h to obtain the iron-based matrix carrier; weigh 15g of potassium carbonate (K2CO3) and dissolve in 20mL of deionized water, then add 5g of diethylene glycol (C4H2O) 10 O3) Stir evenly to form a mixed solution; add 55.5g of iron-based parent carrier to 25mL of the mixed solution and impregnate for 30min with an equal volume, then remove and dry at 70℃ for 5h to obtain the acidic gas dual-function desulfurizer.

[0036] The acid gas dual-function desulfurizer contains 20.3 wt% Fe2O3, 23.5 wt% CaO, 34.7 wt% CaSO4, 14.4 wt% K2O, and 7.10 wt% diethylene glycol.

[0037] Example 3

[0038] Weigh 30g of iron hydroxide (FeOOH), 40g of calcium hydroxide (Ca(OH)2), and 20g of anhydrous calcium sulfate (CaSO4), mix the three materials thoroughly, add 50mL of deionized water and knead for 10min, then extrude into strips using a 3-4mm perforated sheet extruder and dry at 40℃ for 10h to obtain the iron-based matrix carrier; weigh 10g of sodium carbonate (Na2CO3) and dissolve it in 15mL of deionized water, then add 2g of glucose (C6H2O) 12 O6) Stir evenly to form a mixed solution; add 77.2g of iron-based parent carrier to 16mL of the mixed solution and impregnate for 30min with an equal volume, then remove and dry at 70℃ for 10h to obtain the acidic gas dual-function desulfurizer.

[0039] The acid gas dual-function desulfurizer contains 31.7 wt% Fe2O3, 35.6 wt% CaO, 23.5 wt% CaSO4, 6.86 wt% Na2O, and 2.34 wt% glucose.

[0040] Example 4

[0041] Weigh out 40g of iron hydroxide (FeOOH), 50g of calcium hydroxide (Ca(OH)2), and 20g of anhydrous calcium sulfate (CaSO4). Mix the three materials thoroughly, add 60mL of deionized water, knead for 10min, and extrude into strips using a 3-4mm perforated sheet extruder. Dry at 25℃ for 15h to obtain the iron-based matrix carrier. Weigh out 12g of potassium carbonate (K2CO3), dissolve in 15mL of deionized water, and then add 4g of polyethylene glycol (HO(CH2CH2O) with a molecular weight of 200. nH) Stir until a mixed solution is formed; add 93.8g of iron-based parent carrier to 18mL of the mixed solution and impregnate for 30min. After removal, dry at 60℃ for 10h to obtain the acidic gas dual-function desulfurizer.

[0042] The acid gas dual-function desulfurizer contains 33.9 wt% Fe2O3, 35.7 wt% CaO, 18.9 wt% CaSO4, 7.72 wt% K2O, and 3.78 wt% polyethylene glycol.

[0043] Comparative Example 1

[0044] Weigh out 50g of ferrous sulfate (FeSO4·7H2O) and 50g of calcium hydroxide (Ca(OH)2), mix the two materials evenly, add 30mL of deionized water and knead for 10min, extrude into strips using a 3-4mm perforated plate extruder, and dry at 30℃ for 15h to obtain the desulfurizing agent.

[0045] The desulfurizer contains 21.6 wt% Fe2O3, 41.7 wt% CaO, and 36.7 wt% CaSO4.

[0046] Comparative Example 2

[0047] Weigh out 30g of iron hydroxide (FeOOH), 40g of calcium hydroxide (Ca(OH)2), and 20g of anhydrous calcium sulfate (CaSO4). Mix the three materials thoroughly, add 50mL of deionized water and knead for 10min. Extrude the mixture into strips using a 3-4mm perforated sheet extruder and dry at 40℃ for 10h to obtain the desulfurizing agent.

[0048] The desulfurizer contains 34.9 wt% Fe2O3, 39.2 wt% CaO, and 25.9 wt% CaSO4.

[0049] test

[0050] The desulfurizing agents prepared according to the embodiments and comparative examples of the present invention were applied to the desulfurization reaction of acidic gas in a fixed-bed reactor with a catalyst loading of 10 mL and a gas space velocity of 1000 h⁻¹. -1 The reaction was conducted at 50℃ and atmospheric pressure. The simulated gas composition (V / V) was: H₂S 0.1%, CO₂ 0.01%, O₂ 1%, H₂O 2%, CO 20%, with the remainder being CO₂. The sulfur content of the tail gas was determined using a trace sulfur analyzer. Bed breakthrough was considered to occur when the H₂S content exceeded 0.1 ppm. The CO₂ conversion rate was continuously monitored. The experimental results are shown in Table 1.

[0051] Table 1 Performance Test Table

[0052]

[0053] The above data show that the sulfur capacity and organic sulfur hydrolysis activity of the desulfurizing agent of this invention are significantly better than those of the catalyst prepared in the comparative example.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-function desulfurizing agent for acidic gases, characterized in that, It includes an iron-based matrix carrier and active ingredients; the iron-based matrix carrier is Fe2O3, M x O y and M a (SO4) b A mixture, wherein M is selected from at least one group IIA or IIIA metal; the active ingredient is A. c O d A is selected from at least one of Na, K, Li, and Cs.

2. The acidic gas dual-function desulfurizer according to claim 1, characterized in that, M is selected from at least one of Ca, Mg, Ba, B, Al, Ga, and In.

3. The acidic gas dual-function desulfurizer according to claim 1, characterized in that, The active ingredients also include polyols; the polyols are selected from at least one of ethylene glycol, diethylene glycol, glycerol, diglycerol, polyethylene glycol with a molecular weight of 200-600, glucose, fructose, sucrose, and lactose.

4. The acidic gas dual-function desulfurizer according to claim 1 or 3, characterized in that, In the aforementioned acidic gas dual-function desulfurizing agent, A, by mass fraction, c O d It accounts for 2wt%~20wt% of the desulfurizing agent; polyol accounts for 0wt%~10wt% of the desulfurizing agent; and iron-based parent carrier accounts for 70wt%~98wt% of the desulfurizing agent.

5. The acidic gas dual-function desulfurizer according to claim 4, characterized in that, In the iron-based parent carrier, Fe2O3 accounts for 20wt%~60wt% of the carrier mass by weight; M x O y 20wt%~60wt% of the carrier mass; M a (SO4) b It accounts for 20wt% to 60wt% of the carrier mass.

6. The preparation method of the acidic gas bifunctional desulfurizer according to claim 1, characterized in that, Includes the following steps: S1 utilizes iron salt, salt containing M, and water to knead and shape to obtain an iron-based matrix carrier; wherein, at least one of the raw materials, iron salt and salt containing M, contains sulfate ions; S2. Prepare a mixed aqueous solution using a salt containing A; impregnate the iron-based parent carrier obtained in step S1 to obtain the acidic gas bifunctional desulfurizer.

7. The preparation method according to claim 6, characterized in that, In step S1, the iron salt is selected from at least one of ferrous sulfate, ferric hydroxide, and active iron oxide γ-Fe2O3; the salt containing M is selected from at least one of hydroxide, oxide, and sulfate.

8. The preparation method according to claim 6, characterized in that, In step S2, the salt containing A is at least one of oxides, hydroxides, carbonates, and basic carbonates.

9. The preparation method according to claim 6, characterized in that, In step S2, the mixed aqueous solution also includes polyols.

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