Oxygen-resistant multifunctional catalyst for catalytic preparation of sulfur as well as preparation method and application of oxygen-resistant multifunctional catalyst

Abstract

The invention discloses an oxygen-resistant multifunctional catalyst for catalytic preparation of sulfur as well as a preparation method and application thereof, and belongs to the technical field of catalysts. The composition formula of the catalyst is LaMxFeyO3, La is a lanthanum element, M is a transition metal or a rare earth metal element, x is the molar ratio of M / La, and x is greater than or equal to 0.1 and less than or equal to 0.9; y is the molar ratio of Fe / La, and the value range of y is greater than or equal to 0.1 and less than or equal to 0.9. The catalyst provided by the invention has the functions of catalytic reduction and hydrolysis, can meet the requirements of low-temperature-section Claus reaction and high-temperature-section reaction of reducing SO2 by coal gas to prepare sulfur, and can be used under complex atmosphere conditions such as oxygen-containing, water-containing and hydrogen-containing atmosphere conditions. The catalyst disclosed by the invention can be pre-vulcanized under an aerobic atmosphere condition or an anaerobic atmosphere condition, and the activity of the catalyst is improved through pre-vulcanization, so that the yield of sulfur is improved in a catalytic application process.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and specifically relates to an oxygen-resistant multifunctional catalytic catalyst for sulfur production, its preparation method, and its application. Background Technology

[0002] Currently, methods for treating sulfur dioxide tail gas include direct tail gas disposal, acid recovery, regenerative desulfurization, and resource utilization. Among these, acid recovery is often used for low-concentration oxygen-containing SO2 flue gas generated from smelting. To further increase the added value of sulfur resources, there is an urgent need to develop sulfur production technology from low-concentration oxygen-containing smelting flue gas.

[0003] Currently, most SO2-to-sulfur technologies employ Claus and ultra-optimal Claus processes, catalyzing the reaction of H2S and SO2 to produce sulfur. The Claus reaction process flow is as follows: Figure 1 As shown, the process usually includes a sulfur production section and a tail gas treatment section. In the catalytic reaction stage, both stages of the Claus reactor use catalysts. Activated alumina catalyst is the most widely used Claus catalyst at present, while multi-component catalysts are also under development. Foreign companies engaged in the production (research and development) of sulfur recovery catalysts mainly include Axens, BASF, Catalysts & Chemicals Industries, UOP, Criterion and other companies. Domestically, they are mainly Sinopec Qilu Company Research Institute and PetroChina Southwest Oil and Gas Field Company Natural Gas Research Institute. The main varieties of sulfur recovery catalysts at home and abroad are shown in Table 1. They are mainly based on alumina and titanium oxide, and their performance is improved by adding transition metals and other additives. However, Claus catalysts have the following problems: (1) High requirements for flue gas: mainly for high-purity SO2 flue gas in the chemical industry. (3) Have gray hydrogen supply conditions: not only is it necessary to use hydrogen to generate hydrogen sulfide through hydrogenation reaction, but it is also necessary to accurately control the reaction ratio of H2S and SO2. (2) The applicable conditions of the catalyst are relatively strict: it needs to be used under oxygen-free conditions. The presence of oxygen will poison the catalyst and cause deactivation.

[0004] Table 1. Major types of sulfur recovery catalysts at home and abroad.

[0005]

[0006] The Claus process employs corresponding reduction, hydrolysis, and deoxygenation catalysts for different forms of sulfur. However, the stringent operating conditions and high costs limit its application in the smelting industry. Besides the Claus process, Deng Gengfeng et al. (Research on the process of producing sulfur from SO2 in smelting flue gas by reducing it with coal gas, *Journal of Jiangxi University of Science and Technology*, 2010, Vol. 31, No. 1, pp. 32-35) proposed a process for producing sulfur from SO2 in smelting flue gas by reducing it with coal gas. The core catalyst in this process is the Fe / Al2O3 catalyst, which can catalyze the reaction of CO, H2, and SO2 to produce sulfur at 400℃. However, this catalyst has poor selectivity, with hydrogen sulfide being the main product. Furthermore, Al2O3 lacks hydrolysis capabilities, so byproducts such as COS and CS2 cannot be further hydrolyzed to produce sulfur. The presence of oxygen causes the catalyst to deactivate rapidly in long-term experiments, indicating poor oxygen resistance. Therefore, the Fe / Al2O3 catalyst is not the optimal catalyst for producing sulfur from SO2 in smelting flue gas by reducing it with coal gas. Furthermore, Deng Gengfeng et al. (Catalytic Reduction of SO2 in Flue Gas to Sulfur, Materials Reports, 2010, Vol. 24, No. 15, pp. 421-424) pointed out that rare earth-doped catalysts have better performance; the sulfur yield can be increased to 85% after adding 1% Sm, but they still do not have hydrolysis function and cannot improve antioxidant capacity. Additionally, Jia Lishan et al. proposed a LaCoO3 perovskite catalyst for the catalytic production of sulfur from SO2 in flue gas.

[0007] In summary, the reported sulfur-producing catalysts include Al2O3, Fe / Al2O3, rare earth-modified Fe / Al2O3, and LaCoO3 perovskite. While these catalysts demonstrate certain sulfur-producing properties in research reports, they still suffer from the following drawbacks: ① Al2O3-based catalysts have limited functionality, typically exhibiting only Claus reaction performance and lacking hydrolysis capabilities; ② Fe / Al2O3-based catalysts have poor oxygen resistance and rapidly deactivate under oxygen-containing conditions; ③ The pre-sulfurization process for LaCoO3 perovskite catalysts is complex; ④ LaCoO3 perovskite catalysts only possess… The catalysts exhibit high-temperature catalytic performance for the reaction of CO and SO2, but do not show Claus catalytic performance; ⑤ There are no reports on the catalytic reduction of SO2 to sulfur by LaCoO3 perovskite catalysts under coal gas atmosphere; ⑥ The catalysts reported at this stage have stringent operating conditions, requiring strict gas mixing and pretreatment conditions, making them unsuitable for rapid and effective deployment; ⑦ There are no reports on the performance testing of existing catalysts under aqueous conditions, and the results of long-term performance evaluations are unsatisfactory; Given these numerous shortcomings, the catalysts reported at this stage are not well-suited for industrial applications of sulfur production from smelting flue gas.

[0008] Therefore, achieving sulfur production from catalytic reduction flue gas under conditions of low concentration, high oxygen content, and low temperature and energy consumption remains a major challenge in this field. Based on this, this invention proposes a multifunctional low-temperature oxygen-resistant sulfur production catalyst that integrates the Claus reaction and coal gas catalytic reduction reaction, pioneering a new approach for the recovery and utilization of sulfur resources from smelting flue gas and constructing an innovative technological system for the directional conversion of multi-source sulfur resources in metallurgy and power generation to produce sulfur. Summary of the Invention

[0009] To overcome the shortcomings of existing technologies, the main objective of this invention is to provide an oxygen-resistant multifunctional catalytic sulfur production catalyst, its preparation method, and its application. This catalyst is a multifunctional low-temperature oxygen-resistant sulfur production catalyst that integrates Claus reaction and coal gas catalytic reduction reaction, and can be directly applied to sulfur production from oxygen-containing, low-concentration, and complex smelting flue gas.

[0010] To achieve the above objectives, the present invention provides an oxygen-resistant, multifunctional catalytic catalyst for sulfur production, wherein the catalyst has the composition formula LaM x Fe y O3, where La is lanthanum, M is a transition metal or rare earth metal, x is the molar ratio of M / La, and the value of x is 0.1≤x≤0.9; y is the molar ratio of Fe / La, and the value of y is 0.1≤y≤0.9.

[0011] Furthermore, the transition metal element includes one or more of Co, Ni, and Mn, and the rare earth metal element includes one or more of Ce and Sr.

[0012] In another aspect, the present invention provides a method for preparing an oxygen-resistant multifunctional catalytic sulfur production catalyst, the method comprising the following steps: Step S1: Weigh out lanthanum salt, iron salt and M salt according to the stoichiometric molar ratio of each component in the catalyst composition. Step S2: Dissolve the above-mentioned lanthanum salt, iron salt and M salt in water to form a mixed solution, then add a complexing agent and a foaming agent to the mixed solution to obtain a mixture, and heat and stir the mixture to obtain a sol; Step S3: The sol is dried to form a gel, and then the gel is pre-calcined to obtain a powder material; Step S4: The powder material is calcined to obtain the oxygen-resistant multifunctional catalytic sulfur production catalyst.

[0013] Furthermore, the foaming agent is selected from one or both of ethanol and polyethylene glycol.

[0014] Furthermore, the complexing agent is selected from one or both of citric acid and sodium citrate.

[0015] Furthermore, the heating and stirring temperature is 50℃-80℃, and the rotation speed is 200-500r / min.

[0016] Furthermore, the drying temperature is 80℃-100℃, and the drying time is 10-12 hours.

[0017] Furthermore, the calcination temperature is 600-650℃, and the calcination time is 3-6 hours.

[0018] Furthermore, the complexing agent is added in an amount of 10-30% of the total mass of the mixture.

[0019] Furthermore, the amount of foaming agent added accounts for 0.5-5% of the total mass of the mixture.

[0020] Furthermore, in step S2, the mixing process of dissolving lanthanum salt, iron salt and M salt in water is carried out under ultrasonic oscillation conditions, wherein the frequency of ultrasonic oscillation is 5-20Hz and the rotation speed is 20-100r / min.

[0021] In another aspect, the present invention provides the application of the above-mentioned oxygen-resistant multifunctional catalytic sulfur production catalyst in the catalytic reduction of flue gas to produce sulfur.

[0022] Furthermore, the oxygen-resistant multifunctional catalytic sulfur-producing catalyst is first pre-sulfurized under an aerobic or anaerobic atmosphere, and then the pre-sulfurized catalyst is used for the catalytic reduction of flue gas to produce sulfur. The pre-sulfurization includes the following steps: Step S1: Place the oxygen-resistant multifunctional catalytic sulfur production catalyst into the reactor; Step S2: First, inert gas is introduced into the reactor for room temperature purging, and then the reactor is heated to the preset temperature before the gas inlet components are switched. Step S3: Oxygen-containing SO2 gas or oxygen-free SO2 gas and reducing gas CO are introduced into the reactor to pre-sulfurize the catalyst. In the oxygen-containing SO2 gas, the volume fraction of O2 is 1-3% and the volume fraction of SO2 is 2-6%. In the oxygen-free SO2 gas, the volume fraction of SO2 is 5-10%. The volume fraction of the reducing gas CO is twice the sum of the volume fractions of SO2 and O2 or twice the volume fraction of SO2. Step S4: After the catalyst pre-sulfurization is completed, switch the inlet gas components and introduce inert gas into the reactor for purging. Then, cool the catalyst to room temperature at a set cooling rate while maintaining the inert atmosphere until the catalyst is completely cooled.

[0023] Furthermore, in step S3, the pre-vulcanization temperature is 300-450℃ and the time is 1-2 hours.

[0024] Furthermore, during the pre-vulcanization process, the total gas space velocity is 500-800 h⁻¹. -1 The reactor pressure is 0.02-0.1 MPa.

[0025] Compared with the prior art, the present invention has the following beneficial effects: The oxygen-resistant multifunctional catalytic sulfur production catalyst of this invention adopts the iron-based perovskite catalyst LaM x Fe y O3, with transition metals and rare earth metals added in proportion as promoters, M including but not limited to Co, Mn, Ce, Sr, etc. This catalyst possesses both catalytic reduction and hydrolysis functions, capable of supporting both the low-temperature Claus reaction and the high-temperature SO2 reduction to sulfur reaction from coal gas. The oxygen-resistant multifunctional catalytic sulfur production catalyst LaM provided by this invention... x Fe y O3 has the following advantages: ① The catalyst preparation method is simple and can achieve one-step synthesis with the addition of auxiliary agents; ② It has multiple functions such as low temperature Claus, high temperature gas reduction, and hydrolysis reaction, which can meet the stable use under different working conditions; ③ The catalyst has a wide range of operating conditions and can be used in complex atmospheres such as those containing oxygen, water, and hydrogen; ④ The catalyst has a long service life and is stable, and it can react stably for 48 hours without deactivation under 20% water content conditions; ⑤ This catalyst exhibits a sulfur yield of over 80% even without pre-sulfurization under oxygen-containing conditions at 500℃. After pre-sulfurization, the catalytic performance is comprehensively optimized, with the following core effects: 1. The pre-sulfurization process of this invention generates highly active iron sulfide and lanthanum sulfide active phases in the catalyst, activating it and significantly improving its intrinsic activity; 2. It consumes highly active lattice oxygen and forms sulfur-oxygen vacancies, inhibiting the excessive oxidation of elemental sulfur to SO2 and significantly improving the selectivity of the target product; 3. It forms a stable sulfide layer, avoiding phase transformation and loss of active components, enhancing oxygen resistance, optimizing sulfur desorption performance, and resisting sulfur deposition deactivation; 4. It provides active sites suitable for the reaction, optimizes the reaction mechanism, lowers the activation temperature, and balances energy saving and suppression of side reactions. Attached Figure Description

[0026] Figure 1 The figure shows the performance test of the oxygen-free presulfurization catalyst of Example 1 of the present invention in catalyzing the reduction of SO2 from CO to sulfur under oxygen-free conditions; Figure 2 The figure shows the performance test results of the oxygen-free presulfurization catalyst of Example 1 of the present invention in catalyzing the reduction of SO2 from CO to sulfur under oxygen-containing conditions; Figure 3The figure shows the performance test results of the oxygen-free presulfurization catalyst of Example 1 of the present invention in reducing SO2 from H2S to sulfur. Figure 4 The figure shows the performance test of the oxygen-free presulfurization catalyst of Example 2 of the present invention in catalyzing the reduction of SO2 from CO to sulfur under oxygen-free conditions; Figure 5 The figure shows the performance test results of the oxygen-free presulfurization catalyst of Example 2 of the present invention in catalyzing the reduction of SO2 from CO to sulfur under oxygen-containing conditions; Figure 6 The figure shows the performance test results of the oxygen-free presulfurization catalyst of Example 2 of the present invention in reducing SO2 from H2S to sulfur. Figure 7 The graph shows the performance test results of the oxygen-free presulfurization catalyst of Comparative Example 1 of the present invention in catalyzing the reduction of SO2 from CO to sulfur under oxygen-free conditions. Figure 8 The graph shows the performance test results of the oxygen-free presulfurization catalyst of Comparative Example 1 of the present invention in catalyzing the reduction of SO2 from CO to sulfur under oxygen-containing conditions. Figure 9 The graph shows the performance test results of the oxygen-free presulfurization catalyst of Comparative Example 1 of the present invention in reducing SO2 from H2S to sulfur. Figure 10 The graph shows the performance test results of the oxygen-free presulfurization catalyst of Comparative Example 2 of the present invention in catalyzing the reduction of SO2 from CO to sulfur under oxygen-free conditions. Figure 11 The graph shows the performance test results of the oxygen-free presulfurization catalyst of Comparative Example 2 of the present invention in catalyzing the reduction of SO2 from CO to sulfur under oxygen-containing conditions. Figure 12 The diagram shows the performance test results of the oxygen-free pre-sulfurization catalyst of Comparative Example 2 of the present invention in reducing SO2 from H2S to sulfur. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range. The invention will now be described in detail with reference to embodiments.

[0028] To achieve the above objectives, a first aspect of the present invention provides an oxygen-resistant, multifunctional catalytic catalyst for sulfur production, the catalyst having the formula LaM x Fe yO3, where La is lanthanum, M is a transition metal or rare earth metal, x is the molar ratio of M / La, and the value of x ranges from 0.1 to 0.9 (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9); y is the molar ratio of Fe / La, and the value of y ranges from 0.1 to 0.9 (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9).

[0029] The oxygen-resistant multifunctional catalytic sulfur production catalyst of the present invention is based on a perovskite oxide (ABO3) core structure, wherein La 3+ Occupying the A-site lattice, Fe 3+ By controlling the molar ratio of transition metal / rare earth metal promoters M (such as Co, Ni, Mn, Ce, Sr, etc.) to co-occupy B sites, a composite oxide system with both structural stability and catalytic activity is formed. The formulation design of each component in this invention follows the principle of "lattice doping modification-active site enhancement," and the catalytic performance is optimized by precisely controlling the molar ratio of M and Fe to La (both 0.1-0.9).

[0030] Among them, transition metal additives (such as Co, Ni, Mn, etc.) utilize the variable valence state property (such as Co) 2+ / Co 3+ Ni 2+ / Ni 3+ Constructing multiple electron transfer channels enhances redox activity during catalysis and regulates lattice oxygen migration rate to strengthen catalytic conversion efficiency. Rare earth metal additives (such as Ce) utilize their unique 4f electron layer structure and oxygen storage-release capability to optimize the oxygen hole concentration of catalytic materials, inhibit Fe ion aggregation, and improve the structural stability of materials under harsh conditions such as high temperature and high salt.

[0031] By specifically limiting the molar ratio of M to La (0.1≤x≤0.9), the form in which M doping enters the perovskite lattice can be adjusted, lattice parameters can be fine-tuned to enhance the exposure of active sites, and a synergistic catalytic interface can be formed with the perovskite host, improving adaptability to complex reaction systems. Furthermore, by specifically limiting the molar ratio of Fe to La (0.1≤y≤0.9), the content of the core active component Fe can be adjusted, directly determining the density of active sites at B sites. Simultaneously, synergistic interaction sites (such as Fe-O-Fe bonds) can be formed between Fe ions, enhancing the adsorption and activation capacity of reactants. At the same time, the M promoter can also regulate and inhibit the formation of inert phases such as Fe2O3.

[0032] In some preferred embodiments of the present invention, the transition metal element includes one or more of Co, Ni, and Mn, and the rare earth metal element includes one or more of Ce and Sr.

[0033] A second aspect of the present invention also provides a method for preparing an oxygen-resistant multifunctional catalytic sulfur production catalyst, the method employing a sol-gel foaming method and comprising the following steps: Step S1: Weigh out lanthanum salt, iron salt and M salt according to the stoichiometric molar ratio of each component in the catalyst composition. Step S2: Dissolve the above-mentioned lanthanum salt, iron salt and M salt in water to form a mixed solution, then add a complexing agent and a foaming agent to the mixed solution to obtain a mixture, and heat and stir the mixture to obtain a sol; Step S3: The sol is dried to form a gel, and then the gel is pre-calcined to obtain a powder material; Step S4: The powder material is calcined to obtain the oxygen-resistant multifunctional catalytic sulfur production catalyst.

[0034] In a preferred embodiment of the present invention, the foaming agent is selected from one or two of ethanol and polyethylene glycol, and the complexing agent is selected from one or two of citric acid and sodium citrate. The polyethylene glycol used has a molecular weight range of 100-2000.

[0035] In some preferred embodiments of the present invention, lanthanum salts include, but are not limited to, lanthanum nitrate, lanthanum chloride, lanthanum acetate, etc.; cobalt salts include, but are not limited to, cobalt nitrate, cobalt chloride, cobalt acetate, cobalt carbonate, etc.; manganese salts include, but are not limited to, manganese nitrate, manganese chloride, manganese sulfate, manganese acetate, etc.; cerium salts include, but are not limited to, cerium nitrate, cerium chloride, cerium sulfate, cerium acetate, etc.; strontium salts include, but are not limited to, strontium nitrate, strontium chloride, strontium sulfate, strontium acetate, strontium carbonate, etc.; and iron salts include, but are not limited to, ferric nitrate, ferric chloride, ferric sulfate, ferric acetate, etc.

[0036] To further improve the reaction performance of the prepared catalyst, in a preferred embodiment of the present invention, the heating and stirring temperature is 50℃-80℃ and the rotation speed is 200-500 r / min; the drying temperature is 80℃-100℃ and the drying time is 10-12 h; the calcination temperature is 600-650℃ and the calcination time is 3-6 h.

[0037] In some preferred embodiments of the present invention, the complexing agent is added at a rate of 10-30% of the total mass of the mixture. The foaming agent is added at a rate of 0.5-5% of the total mass of the mixture. Further, according to mass percentage, the optimal content range of each raw material in the oxygen-resistant multifunctional catalytic sulfur production catalyst is 10%-30% lanthanum salt, 2%-10% iron salt, 0.5%-20% auxiliary agent M salt, 10%-30% complexing agent, 0.5%-5% foaming agent, and 20%-70% water.

[0038] In a preferred embodiment of the present invention, in step S2, the mixing process of dissolving the lanthanum salt, iron salt, and M salt in water is carried out under ultrasonic vibration conditions. The frequency of the ultrasonic vibration is 5-20 Hz, and the rotation speed is 20-100 r / min. By introducing ultrasonic vibration conditions during the preparation process, the salt solution can be mixed thoroughly and uniformly, resulting in powder particles with smaller particle size and larger specific surface area, which is beneficial to improving the reaction performance of the catalyst.

[0039] The method for preparing the oxygen-resistant multifunctional catalytic sulfur-producing catalyst of the present invention, in addition to the above-mentioned sol-gel foaming method, can also employ methods including but not limited to impregnation and co-precipitation. The impregnation method for preparing the oxygen-resistant multifunctional catalytic sulfur-producing catalyst includes the following steps: first, preparing LaFeO3 catalyst powder; then, preparing an auxiliary agent M salt solution; impregnating the LaFeO3 catalyst powder with an equal volume to prepare the catalyst precursor; drying the obtained catalyst precursor; and then calcining it to obtain the oxygen-resistant multifunctional catalytic sulfur-producing catalyst. The co-precipitation method for preparing the oxygen-resistant multifunctional catalytic sulfur-producing catalyst includes the following steps: mixing a lanthanum salt solution, an iron salt solution, an auxiliary agent M salt solution, and a precipitant (urea, etc.), then heating to produce a precipitate; drying the obtained precipitate; and then calcining it to obtain the oxygen-resistant multifunctional catalytic sulfur-producing catalyst.

[0040] In a third aspect of the embodiments of the present invention, the application of the aforementioned oxygen-resistant multifunctional catalytic sulfur production catalyst in the catalytic reduction of flue gas to produce sulfur is also provided.

[0041] The catalyst of this invention possesses both Claus properties for catalyzing the reaction of H2S and SO2 and the properties for catalyzing the reduction of SO2 from coal gas to produce sulfur. It is a multifunctional low-temperature oxygen-resistant sulfur production catalyst. In the low-temperature range of 200-300℃, the Claus reaction is dominant, while in the high-temperature range of 500-600℃, the reaction of reducing SO2 from coal gas to produce sulfur is dominant.

[0042] Furthermore, in the above application process, the oxygen-resistant multifunctional catalytic sulfur-producing catalyst is first pre-sulfurized under an aerobic or anaerobic atmosphere, and then the pre-sulfurized catalyst is used for the catalytic reduction of flue gas to produce sulfur. The pre-sulfurization includes the following steps: Step S1, Sample loading: Place the oxygen-resistant multifunctional catalytic sulfur production catalyst into the reactor; Step S2, inert gas purging: First, inert gas is introduced into the reactor for room temperature purging, and then the reactor is heated to the preset temperature and the gas inlet components are switched. Step S3, Pre-sulfurization: Oxygen-containing SO2 gas or oxygen-free SO2 gas and reducing gas CO are introduced into the reactor to pre-sulfurize the catalyst; wherein, in the oxygen-containing SO2 gas, the volume fraction of O2 is 1-3% and the volume fraction of SO2 is 2-6%; in the oxygen-free SO2 gas, the volume fraction of SO2 is 5-10%; and the volume fraction of reducing gas CO is twice the sum of the volume fractions of SO2 and O2 or twice the volume fraction of SO2. Step S4, Inert gas purging: After the catalyst pre-sulfurization is completed, switch the inlet gas components and introduce inert gas into the reactor for purging. Then, cool the catalyst to room temperature at a set cooling rate while maintaining an inert atmosphere until the catalyst is cooled completely.

[0043] Because the oxygen-resistant multifunctional catalytic sulfur production catalyst of the present invention has oxygen resistance, it can be pre-sulfurized under oxygen-containing or oxygen-free atmosphere conditions. Through pre-sulfurization, the metal oxides on the catalyst surface react with the sulfiding agent to generate active metal sulfides (La2O3→La2S3), thereby improving the activity of the catalyst and thus increasing the sulfur yield during catalytic application.

[0044] During the pre-sulfurization process under aerobic atmosphere, the volume fraction of O2 in the oxygen-containing SO2 gas needs to be controlled at 1-3% to avoid excessive concentration leading to catalyst oxidation. The volume fraction of SO2 should be 2-6% to match the actual on-site operating conditions. The volume fraction of CO in the reducing gas should be twice the sum of the volume fractions of SO2 and O2, or twice the volume fraction of SO2, to ensure that the residual amount of the reducing agent after reacting with oxygen and SO2 meets the stoichiometric ratio of 2:1, achieving complete reaction (2CO + SO2 = S + 2CO2). Too much reducing gas will reduce S to COS, while too little reducing gas will result in excessive unreacted SO2 residue.

[0045] In some preferred embodiments of the present invention, in step S3, during the pre-vulcanization process, the temperature is increased to the target vulcanization temperature at a rate of 2-5℃ / min for isothermal vulcanization, wherein the target vulcanization temperature is 300-450℃ (e.g., 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, 420℃, 440℃, 450℃), and the vulcanization time is 1-2 hours; during the pre-vulcanization process, the total gas space velocity is 500-800 h⁻¹. -1 (For example, it can be 500h) -1 550h -1 600h -1 650h -1 700h -1 750h -1 800h -1The reactor pressure is 0.02-0.1 MPa. Under these conditions, the sulfidation temperature is close to the reaction temperature, resulting in high activation of surface sulfur species and rapid generation of active sulfur species. Controlling the sulfidation time to 1-2 hours allows for the formation of an active sulfidation layer on the catalyst surface, enhancing the catalyst's oxygen resistance and preventing poisoning and deactivation. It also avoids deep sulfidation that could damage the catalyst structure. The space velocity and pressure are matched to actual field conditions, and the results closely reflect real-world requirements.

[0046] In an optional embodiment of the present invention, in step S1, the oxygen-resistant multifunctional catalytic sulfur production catalyst is crushed and sieved to 20-40 mesh (the specific size can be adjusted according to the specifications of the reaction device), and the amount of oxygen-resistant multifunctional catalytic sulfur production catalyst placed in it is controlled according to the reactor volume filling rate of 30%-50%.

[0047] In a preferred embodiment of the present invention, in step S2, when an inert gas (nitrogen or argon, purity ≥ 99.99%) is introduced, the gas space velocity is controlled to be 500-1000 h⁻¹. -1 The pressure inside the reactor is maintained at 0.1-0.3 MPa. After purging at room temperature for 30-60 minutes, the reactor temperature is programmed to rise (heating rate 5-10℃ / min) to the preset temperature (150-200℃).

[0048] In a preferred embodiment of the present invention, in step S4, the inlet gas component is switched, and an inert gas is introduced into the reactor for purging, wherein the purging time is 1-2 hours and the gas space velocity is 800-1200 h⁻¹. -1 The cooling rate is 5-10℃ / min.

[0049] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0050] Example 1 An oxygen-resistant, multifunctional catalytic catalyst for sulfur production, the catalyst having the formula LaM x Fe y O3, where x is the molar ratio of M / La, with a value of 0.8, y is the molar ratio of Fe / La, with a value of 0.2, and M is cobalt.

[0051] Its preparation method includes the following steps: Step S1: Weigh out lanthanum nitrate, ferric nitrate, and cobalt nitrate according to the stoichiometric molar ratio of each component in the catalyst composition. Step S2: Dissolve the above-mentioned lanthanum nitrate, ferric nitrate, and cobalt nitrate in water for 30 minutes until completely dissolved and mixed to form a mixed solution. Then, mix the above mixed solution with citric acid (20% by mass), which is an equimolar amount of the total amount of metal nitrates, and stir until homogeneous. Next, add ammonia water to adjust the pH of the mixture to 6-7. Subsequently, add a small amount of polyethylene glycol (3% by mass) and heat the resulting solution at 75°C. o Continue stirring at temperature C until a stable gel is formed; Step S3, the above sol is subjected to a temperature of 130°C. o After drying at C for 12 hours, a porous dry gel is formed. The dry gel is then subjected to auto-ignition to obtain a powder material.

[0052] Step S4: The powder material is then further calcined in a tube furnace at a temperature of 600°C for 2 hours to obtain the oxygen-resistant multifunctional catalytic sulfur production catalyst of this embodiment.

[0053] Example 2 An oxygen-resistant, multifunctional catalytic catalyst for sulfur production and its preparation method are disclosed. The only difference between this catalyst and Example 1 is the raw material ratio. The catalyst's composition formula is LaM... x Fe y O3, where x is 0.2, y is the molar ratio of Fe / La, y is 0.8, and M is nickel.

[0054] Example 3 An oxygen-resistant, multifunctional catalytic catalyst for sulfur production and its preparation method are disclosed. The only difference between this catalyst and Example 1 is the raw material ratio. The catalyst's composition is LaM... x Fe y O3, where x is 0.5, y is the molar ratio of Fe / La, and M is manganese.

[0055] Example 4 An oxygen-resistant, multifunctional catalytic catalyst for sulfur production and its preparation method are disclosed. The catalyst has the compositional formula LaM. x Fe y O3, where x is the molar ratio of M / La, with a value of 0.8, y is the molar ratio of Fe / La, with a value of 0.2, and M represents cobalt and cerium.

[0056] Example 5 An oxygen-resistant multifunctional catalytic sulfur production catalyst and its preparation method are disclosed. The only difference between this catalyst and Example 1 is the amount of organic additives. The complexing agent of this catalyst accounts for 30% of the total mass of the mixture, and polyethylene glycol accounts for 0.5% of the total mass of the mixture.

[0057] Example 6 An oxygen-resistant multifunctional catalytic sulfur production catalyst and its preparation method are disclosed. The only difference between this catalyst and Example 1 is the powder calcination method. The powder obtained after the catalyst dry gel self-ignition is not further calcined in a tube furnace.

[0058] Comparative Example 1 A sulfur catalyst having the formula LaFe y O3, where y is the molar ratio of Fe / La, and the value of y is 1.

[0059] Comparative Example 2 A sulfur catalyst having the formula LaM x O3, where x is the molar ratio of M / La, and the value of x is 1.

[0060] Comparative Example 3 A sulfur catalyst having the formula LaM x Fe y O3, where x is the molar ratio of M / La, with a value of 0.05, and y is the molar ratio of Fe / La, with a value of 0.95.

[0061] Performance testing: The above-described embodiments and comparative examples of sulfur catalyst performance testing methods for sulfur production: The experimental apparatus consists of a gas distribution system, a flow control system, a catalytic reactor, and a flue gas analysis system.

[0062] (1) Anaerobic pre-sulfurization: The catalysts of the above examples and comparative examples were pressed into tablets and placed in a fixed-bed reactor for pre-sulfurization under anaerobic conditions. The pre-sulfurization process included: Step S1, Sample loading: Crush the oxygen-resistant multifunctional catalytic sulfur production catalyst and load it into the constant temperature zone of the fixed bed reactor (loading rate 40%). Fix both ends with quartz wool to prevent the catalyst from being lost due to airflow impact. Check the reactor's sealing performance (pressurize with nitrogen for 30 minutes, pressure drop ≤0.02MPa is acceptable), and connect the inlet, outlet and detection pipelines.

[0063] Step S2, inert gas purging: First, inert gas (nitrogen) is introduced into the fixed-bed reactor for purging at room temperature. After 30 minutes (controlling the gas space velocity to 800 h⁻¹), -1 The pressure inside the reactor is maintained at 0.2 MPa. Then the reactor is programmed to heat up (heating rate of 8℃ / min) to 180℃ before the intake gas components are switched.

[0064] Step S3, Pre-sulfurization: Oxygen-free SO2 gas and reducing gas CO are introduced into the reactor for isothermal pre-sulfurization of the catalyst; wherein the volume fraction of SO2 in the oxygen-free SO2 gas is 5%, the volume fraction of CO in the reducing gas is 10%, and the remainder is a balance atmosphere; the total space velocity (HSV) during pre-sulfurization is 600 h⁻¹. -1 The reactor pressure was 0.5 MPa, the pre-vulcanization temperature was 400℃, the time was 1.5 h, and the pre-vulcanization heating rate was 3℃ / min.

[0065] Step S4, Inert Gas Purging: After the catalyst pre-sulfurization is completed, switch the inlet gas composition and introduce inert gas into the reactor for purging (gas space velocity is 1000 h⁻¹). -1 The catalyst was purged for 1.5 hours, and then cooled to room temperature at a rate of 8°C / min while maintaining an inert atmosphere until the catalyst was completely cooled.

[0066] (2) Pre-sulfurization under aerobic conditions: The oxygen-resistant multifunctional catalytic sulfur production catalyst is pre-sulfurized under aerobic conditions. The only difference between this and the pre-sulfurization process under anaerobic conditions is that oxygen-containing SO2 gas is used for pre-sulfurization in the pre-sulfurization process. The volume fraction of O2 is 2%, the volume fraction of SO2 is 5%, and the volume fraction of reducing gas CO is 14%.

[0067] The catalysts of the above-mentioned pre-sulfurized and unpre-sulfurized examples and comparative examples were tested for their catalytic SO2 reduction to sulfur production performance under five test conditions: ① Under anaerobic conditions of coal gas reduction, the catalyst pre-sulfurized under anaerobic conditions was introduced into the flue gas, and the SO2 conversion rate was tested. The flue gas composition was: 50 mL / min 10% SO2 + 50 mL / min 20% CO; the test results of Examples 1-2 are as follows. Figure 1 and Figure 4 For the test results of Comparative Examples 1-2, please refer to [link / reference]. Figure 7 and Figure 10 It can be observed that under these conditions, the SO2 conversion rate of Examples 1-2 is higher than that of Comparative Examples 1-2.

[0068] ② Under oxygen-assisted conditions, the catalyst pre-sulfurized under anaerobic conditions was passed into flue gas to test the SO2 conversion rate. The flue gas composition was: 38.5 mL / min (10% SO2 + 6% O2) + 61.5 mL / min 20% CO; the test results of Examples 1-2 are available in [reference needed]. Figure 2 and Figure 5 For the test results of Comparative Examples 1-2, please refer to [link / reference]. Figure 8 and Figure 11 It can be observed that under these conditions, the SO2 conversion rate of Examples 1-2 is higher than that of Comparative Examples 1-2.

[0069] ③ Under anaerobic H2S reduction conditions, the catalyst pre-sulfurized under anaerobic conditions was introduced into the flue gas, and the SO2 conversion rate was tested. The flue gas composition was: 50 mL / min 1% SO2 + 50 mL / min 2% H2S. The test results of Examples 1-2 are available in [reference needed]. Figure 3 and Figure 6 For the test results of Comparative Examples 1-2, please refer to [link / reference]. Figure 9 and Figure 12 It can be observed that under these conditions, the SO2 conversion rate of Examples 1-2 is higher than that of Comparative Examples 1-2.

[0070] ④ Under oxygen-assisted conditions, the conversion rate of SO2 was tested by passing the unpre-sulfurized catalyst into the flue gas. The flue gas composition was: 38.5 mL / min (10% SO2 + 6% O2) + 61.5 mL / min 20% CO.

[0071] ⑤ Under the anaerobic reaction conditions of coal gas reduction, the catalyst pre-sulfurized under aerobic conditions was introduced into the flue gas to test the conversion rate of SO2. The flue gas composition was: 50 mL / min 10% SO2 + 50 mL / min 20% CO.

[0072] In the above test, the proportions of SO2, O2, and CO were volume fractions, with N2 as the remaining gas, and a space velocity of 3000 h⁻¹. -1 The reaction temperature was controlled between 150℃ and 550℃. The performance test results are shown in Table 2.

[0073] Table 2

[0074] The above comparison reveals that: (1) the performance of the catalyst after pre-sulfurization is significantly improved compared to the untreated sample, indicating that the pre-sulfurization process generates active species, improves catalytic performance, and reduces the required reaction temperature; (2) the performance of the catalyst after anaerobic pre-sulfurization under oxygen-containing conditions is slightly lower than that under anaerobic conditions, indicating that the presence of oxygen will have a certain toxic effect on the catalyst and reduce its catalytic performance; (3) the catalysts not described in this invention have extremely poor performance under oxygen-containing conditions and are difficult to use stably in an oxygen-containing atmosphere; (4) the catalyst structures do not differ much in their performance for H2S to reduce SO2, but their performance for CO to reduce SO2 differs significantly. Overall performance analysis shows that the catalyst described in this invention not only has excellent catalytic performance under anaerobic conditions, but also exhibits stable high catalytic performance under oxygen-containing conditions.

[0075] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. The present invention can also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of the present invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. An oxygen-tolerant multifunctional catalytic sulfur production catalyst, characterized by, The composition formula of the catalyst is LaM x Fe y O3, wherein La is a lanthanum element, M is a transition metal or a rare earth metal element, x is a molar ratio of M / La, the value range of x is 0.1≤x≤0.9; y is a molar ratio of Fe / La, the value range of y is 0.1≤y≤0.

9.

2. The oxygen tolerant multifunctional catalytic sulfur production catalyst according to claim 1, characterized in that, The transition metal elements include one or more of Co, Ni, and Mn, and the rare earth metal elements include one or more of Ce and Sr.

3. The method for producing the oxygen-resistant multifunctional sulfur production catalyst according to claim 1 or 2, characterized by, The method is prepared by a sol-gel foaming method, and comprises the following steps: In step S1, according to the stoichiometric molar ratio of each component in the catalyst composition, lanthanum salt, iron salt and M salt are weighed; In step S2, the lanthanum salt, iron salt and M salt are dissolved in water to form a mixed solution, and then the mixed solution is added to a complexing agent and a foaming agent to obtain a mixture, and the mixture is heated and stirred to obtain a sol; In step S3, the sol is dried to form a gel, and then the gel is pre-fired to obtain a powder material; In step S4, the powder material is calcined to obtain the oxygen-resistant multifunctional catalytic sulfur production catalyst.

4. The method of claim 3, wherein the method is characterized by, The foaming agent is selected from one or both of ethanol and polyethylene glycol, and the complexing agent is selected from one or both of citric acid and sodium citrate.

5. The method of claim 3, wherein the method is characterized by: The temperature for heating and stirring is 50-80°C, and the rotation speed is 200-500 r / min; the drying temperature is 80-100°C, and the drying time is 10-12 h; and the calcination temperature is 600-650°C, and the calcination time is 3-6 h.

6. The method of claim 3, wherein the method is characterized by: The addition amount of the complexing agent accounts for 10-30% of the total mass of the mixture, and the addition amount of the foaming agent accounts for 0.5-5% of the total mass of the mixture.

7. The method of claim 3, wherein the method is characterized by, In step S2, the mixing process of dissolving the lanthanum salt, iron salt and M salt in water is carried out under ultrasonic oscillation conditions, and the frequency of the ultrasonic oscillation is 5-20 Hz, and the rotation speed is 20-100 r / min.

8. Use of the oxygen-resistant multifunctional catalytic sulfur production catalyst according to claim 1 or 2 in catalytic reduction of flue gas to produce sulfur.

9. Use according to claim 8, characterized in that, The oxygen-resistant multifunctional catalytic sulfur production catalyst is first pre-sulfurized under an oxygen-containing atmosphere or an oxygen-free atmosphere, and then the pre-sulfurized catalyst is used for catalytic reduction of flue gas to produce sulfur, and the pre-sulfurization comprises the following steps: In step S1, the oxygen-resistant multifunctional catalytic sulfur production catalyst is placed in a reactor; In step S2, inert gas is first introduced into the reactor for normal-temperature purging, and then the reactor is subjected to programmed temperature rise to a preset temperature, and then the gas composition is switched; In step S3, oxygen-containing SO2 gas or oxygen-free SO2 gas is introduced into the reactor together with reducing gas CO to pre-sulfurize the catalyst; In the oxygen-containing SO2 gas, the volume fraction of O2 is 1-3%, and the volume fraction of SO2 is 2-6%; in the oxygen-free SO2 gas, the volume fraction of SO2 is 5-10%; The volume fraction of the reducing gas CO is twice the sum of the volume fractions of SO2 and O2 or twice the volume fraction of SO2; In step S4, after the pre-sulfurization of the catalyst is completed, the gas composition is switched, inert gas is introduced into the reactor for purging, and then the catalyst is cooled to room temperature at a preset cooling rate, and the inert atmosphere is maintained until the cooling of the catalyst is completed.

10. Use according to claim 9, characterized in that, In step S3, the temperature of the pre-vulcanization is 300-450℃, and the time is 1-2h; during the pre-vulcanization, the total gas space velocity is 500-800h -1 , and the reactor pressure is 0.02-0.1MPa.

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