Preparation method and application of catalytic hydrolysis-hydrogenation coupling desulfurization catalyst

Abstract

The invention discloses a preparation method and application of a catalytic hydrolysis-hydrogenation coupling desulfurization catalyst, and belongs to the technical field of environment-friendly materials. The preparation method comprises the following steps: dissolving ammonium molybdate as a precursor in water, adding a metal oxide as a carrier, drying, and carrying out temperature programming in a CS2 / H2 mixed atmosphere to obtain the composite catalyst. The catalyst has two functions of catalytic hydrolysis and hydro-conversion desulfurization, and can convert organic sulfur in coal gas through catalytic hydrolysis-hydrogenation coupling at low temperature. The MoO2 / MoS2 composite material can be regenerated and recycled after being soaked in alkali liquor and purged by N2, the MoO2 and MoS2 structures in the recycled catalyst are kept complete, the chemical form is stable, and the MoO2 / MoS2 composite material has good conductivity and ion diffusivity, can be rapidly charged and discharged, and can be used for capacitors. The catalyst provided by the invention provides an effective technical support for deep desulfurization of coal gas, and also provides a thought for resource utilization of the desulfurization catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection, and in particular to a preparation method and application of a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst. Background Art

[0002] In the production process of steel, coking, and nonferrous metal industries, a large amount of coal gas is produced as a by-product. The total amount of these by-product gases can reach trillions of cubic meters per year, and is showing an increasing trend year by year. By-product coal gas is the main source of production fuel for enterprises. With the improvement of national policy requirements and the advancement of technology, the high-value recovery and utilization of industrial coal gas has become a development trend. Sulfur-containing pollutants in coal gas limit its high-value resource utilization. Taking blast furnace gas as an example, blast furnace gas is a by-product of the ironmaking process. The main components include carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2), methane (CH4) and other gases. There are also sulfides such as COS, CS2, H2S, sulfide, and mercaptan. The total sulfur concentration is 100-200 mg·Nm -3 , which will affect the quality of the gas and the subsequent CO x The existing technology for removing H2S from blast furnace gas is quite mature. However, since organic sulfur is stable and difficult to remove directly, conventional desulfurization methods cannot achieve the requirements of deep desulfurization. Therefore, efficient removal of organic sulfur from gas has become a key issue in gas purification.

[0003] At present, conventional organic sulfur conversion technologies in blast furnace gas mainly include hydrogenation conversion (HDS) and catalytic hydrolysis conversion and adsorption. For example, patent CN105772036A discloses a method for preparing a carbon-supported monolayer molybdenum disulfide composite catalyst for low-temperature hydrogenation conversion of carbonyl sulfide. Although single hydrodesulfurization technology can effectively remove organic sulfur, it requires a higher reaction temperature, which limits its application potential at low temperatures and has problems with the stability and regeneration effect of the catalyst. While separate hydrolysis desulfurization technologies, such as CN115445602A, which discloses a method for preparing and applying a catalyst for carbonyl sulfide hydrolysis, can achieve the conversion of carbonyl sulfide, it cannot show sufficient desulfurization efficiency when treating multiple organic sulfurs. In contrast, catalytic hydrolysis-hydrogenation coupled desulfurization technology combines the synergistic effect of hydrogenation reaction and hydrolysis reaction, can significantly improve the desulfurization efficiency, and can operate at a lower temperature, thereby overcoming the limitations of single hydrogenation or hydrolysis technology.

[0004] Molybdenum-based materials, especially molybdenum sulfide (MoS2) and molybdenum dioxide (MoO2), play an important role in catalytic reactions. Molybdenum sulfide (MoS2) has abundant sulfur vacancies, which can significantly enhance the activity of hydrogenation reactions and is suitable for hydrodesulfurization; while molybdenum dioxide (MoO2) has abundant oxygen vacancies, which can effectively promote hydrolysis reactions. Therefore, the composite structure of these two materials exhibits excellent performance in the catalytic hydrolysis-hydrogenation coupling effect. The composite catalyst of molybdenum sulfide and molybdenum dioxide can not only provide a wider range of catalytic reaction sites, but also enhance the desulfurization efficiency of the catalyst through the synergistic effect of different vacancies. In addition, MoO2-MoS2 composite materials have shown broad application prospects in high-power application fields such as supercapacitors due to their excellent electrical conductivity and ion diffusion capacity. For example, CN109207957A discloses a preparation method for MoO2-MoS2 composite materials, proposes their application in supercapacitors, and demonstrates their superior performance as electrode materials. However, this synthesis method requires a higher reaction temperature, reaching above 800°C, and sulfur vapor is in excess. The mass ratio of S to MoO3 powder is as high as 100:3. This method has safety issues caused by sulfur vapor clogging the instrument.

[0005] Therefore, in order to address the problems of low hydrolysis conversion efficiency and high desulfurization temperature of organic sulfur in coal gas, a MoO2-MoS2 composite catalyst was developed to deeply remove various organic sulfur impurities through catalytic hydrolysis-hydrogenation coupling at a lower temperature, and further remove hydrogen sulfide gas to achieve deep desulfurization of coal gas. This is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0006] In light of this, the present invention provides a method for preparing a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst and its application. The present invention utilizes a temperature-programmed reduction method to prepare a MoO2-MoS2 composite catalyst. This simple preparation method exhibits excellent low-temperature catalytic hydrolysis-hydrogenation performance and stability. The catalyst can be recycled after regeneration through alkaline solution impregnation and N2 purge, and the recycled catalyst is then reclaimed as a resource.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst comprises the following steps:

[0009] (1) dissolving ammonium molybdate tetrahydrate in water to form an ammonium molybdate solution, and then adding ammonia water dropwise to adjust the pH to 8-9;

[0010] (2) drying the solution to obtain a solid;

[0011] (3) The dried solid material is placed in the center of a tube furnace and heated and calcined in a mixed atmosphere of 0.5-1% CS2 and 3-5% H2 to obtain a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst.

[0012] Furthermore, the step (1) further includes adding M2O3 before adding ammonia water;

[0013] Wherein, the M2O3 is any one of Al2O3, La2O3 and Tm2O3.

[0014] Furthermore, the volume concentration of the ammonia water added dropwise in step (1) is 2-5%.

[0015] Further, in step (1), the mass ratio of ammonium molybdate tetrahydrate to M2O3 is 1-3:2-6.

[0016] Furthermore, in step (2), the drying temperature is 100-120° C., and the drying time is 10-12 hours.

[0017] Furthermore, in the mixed atmosphere of step (3), the volume proportion of CS2 is 0.5-1%, the volume proportion of H2 is 3-5%, and the rest is N2.

[0018] Furthermore, the calcination in step (3) is performed by heating from room temperature to 400-450°C at a heating rate of 2-5°C / min and keeping the temperature for 3-4 hours.

[0019] The present invention also provides the use of the catalytic hydrolysis-hydrogenation coupled desulfurization catalyst prepared by the above method in removing organic sulfur from coal gas, comprising the following steps:

[0020] 1) Blast furnace gas is passed into a fixed-bed quartz tube reactor, and a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst is used to catalyze the hydrolysis-hydrogenation conversion of organic sulfur in the blast furnace gas, thereby converting the difficult-to-remove organic sulfur (carbonyl sulfide, carbon disulfide, methyl mercaptan) into easily removable inorganic sulfur (H2S);

[0021] 2) The coal gas after organic sulfur removal is sent to the hydrogen sulfide removal tower, where alkali-modified activated carbon is used to adsorb and purify the H2S contained in the coal gas to achieve precise H2S removal;

[0022] 3) After desulfurization is completed, the catalytic hydrolysis-hydrogenation coupled desulfurization catalyst with reduced desulfurization efficiency is immersed in a 0.5-1 mol / L alkaline solution for 2-3 hours, and then heated to 180-200°C under a 60-80 mL / min N2 atmosphere for 2-3 hours to complete regeneration. The conversion rate of the regenerated hydrogenation-hydrolysis coupled desulfurization catalyst can be increased to more than 95%, and it can be recycled 3-5 times;

[0023] The conversion rate of the hydrogenation-hydrolysis coupled desulfurization catalyst after regeneration can be increased to more than 95%.

[0024] 4) The desulfurization catalyst after recycling is recycled and used as a negative electrode material for lithium-ion batteries after the excess S element is blown off with H2 and N2.

[0025] Furthermore, in step 1), the flow rate of blast furnace gas is 150-200 mL / min, and the reaction space velocity is 30,000-40,000 h -1 , relative humidity is 5%-10%RH.

[0026] The catalytic hydrolysis-hydrogenation coupled desulfurization catalyst prepared by the present invention can achieve a catalytic hydrolysis-hydrogenation conversion rate of more than 98% for organic sulfur in coal gas at 150-170° C. and maintain a catalytic stability of more than 95% within 70 hours.

[0027] Furthermore, in step 4), a specific method for resource utilization of the spent catalytic hydrolysis-hydrodesulfurization catalyst is as follows:

[0028] 5-10g of spent catalytic hydrolysis-hydrodesulfurization catalyst was placed in a tubular furnace and calcined in a mixed atmosphere of 5-10% H2 and N2 at a gas flow rate of 100-150ml / min, a temperature of 180-200°C, and a duration of 2-4 hours. The high-temperature H2 and N2 atmosphere removed excess sulfur (S) from the catalyst, thereby improving the conductivity of the MoO2-MoS2 composite catalyst. The MoO2-MoS2 composite catalyst, with excess sulfur removed, was capable of 40-50 charge-discharge cycles at a rated current density of 80-100mA / g, and its discharge specific capacity remained stable after multiple cycles.

[0029] The beneficial effects of the present invention are:

[0030] The composite catalyst of this invention efficiently catalyzes hydrolysis-hydrogenation coupled desulfurization at 160°C, converting organic sulfur in coal gas by combining sulfur vacancies in MoS2 with oxygen vacancies in MoO2. The catalyst exhibits a synergistic effect in the hydrogenation and hydrolysis reactions, increasing desulfurization efficiency by over 40%.

[0031] 2. The catalyst can be regenerated by soaking in alkaline solution and purging with N2, and can be recycled more than 3 times. The catalytic performance remains stable after each regeneration, reducing the cost of catalyst replacement.

[0032] 3. The composite catalyst is prepared by programmed temperature reduction, which is a simple process and suitable for large-scale production. The evenly distributed active sites in the catalyst and its high catalytic performance make it suitable for industrial applications.

[0033] 4. The recycled catalyst can be used as a negative electrode material for lithium-ion batteries after excess sulfur is purged with H2 and N2, exhibiting excellent electrochemical performance. This enables resource utilization and reduces environmental pollution from waste disposal. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 50-cycle performance curve of the catalytic hydrolysis-hydrogenation coupled desulfurization catalyst of Examples 1-3 at a current density of 100 mA / g;

[0035] Figure 2 The XRD patterns of the catalysts prepared in Examples 1-3 are as follows;

[0036] Figure 3 Figure 1 is a graph of the O vacancy and S vacancy content of the catalysts prepared in Examples 1-3;

[0037] Figure 4 Elemental analysis of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Example 1

[0040] 3g(NH4)6Mo7O 24 ·4H2O was dissolved in 30 mL of deionized water, and 2% NH3·H2O was added to adjust the pH to 8. The product was then dried in an oven at 120°C for 12 hours. The dried solid was placed in the center of a tube furnace and heated from room temperature to 400°C at a rate of 5°C / min in a 0.5% CS2 / 5% H2 mixed atmosphere, where it was maintained for 4 hours, to obtain catalytic hydrolysis-hydrogenation coupled desulfurization catalyst A.

[0041] Catalyst A was passed through a 40-60 mesh sieve, and 0.2 g of the sieved catalyst was placed in a fixed-bed quartz tube reactor. 100 ppm COS, 30 ppm CS2, 5 vol% H2, N2 were used as carrier gases to simulate blast furnace gas. The total flow rate was controlled at 200 mL / min, and the reaction space velocity was 40,000 h -1 , relative humidity is 5%, and the catalyst is used to catalyze hydrolysis-hydrogenation coupling conversion of COS, CS2 and CH3SCH3 in blast furnace gas.

[0042] The catalyst performance was tested at 160°C. The conversion rates of COS, CS2 and CH3SCH3 of catalytic hydrolysis-hydrogenation coupled desulfurization catalyst A were 65%, 62% and 57% under hydrolysis catalysis only, and 100%, 100% and 98% after adding H2. The H2S yield was 60% under hydrolysis catalysis only, and 98% after adding H2.

[0043] Example 2

[0044] 3g(NH4)6Mo7O 24 ·4H2O was dissolved in 30 mL of deionized water, 6 g of γ-Al2O3 was added, and 2% NH3·H2O was added to adjust the pH to 8. The mixture was then dried in an oven at 120°C for 12 hours. The dried solid was placed in the center of a tube furnace and heated from room temperature to 400°C at a rate of 5°C / min in a 0.5% CS2 / 5% H2 mixed atmosphere, where it was maintained for 4 hours, to obtain catalytic hydrolysis-hydrogenation coupled desulfurization catalyst B.

[0045] Catalyst B was passed through a 40-60 mesh sieve, and 0.2 g of the sieved catalyst was placed in a fixed-bed quartz tube reactor. 100 ppm COS, 30 ppm CS2, 5 vol% H2, N2 were used as carrier gases to simulate blast furnace gas. The total flow rate was controlled at 200 mL / min, and the reaction space velocity was 40,000 h -1 , relative humidity is 5%, and the catalyst is used to catalyze hydrolysis-hydrogenation coupling conversion of COS, CS2 and CH3SCH3 in blast furnace gas.

[0046] The catalyst performance was tested at 160°C. The conversion rates of COS, CS2 and CH3SCH3 of catalytic hydrolysis-hydrogenation coupled desulfurization catalyst B were 70%, 66% and 65% under hydrolysis catalysis only. After the addition of H2, COS, CS2 and CH3SCH3 were completely converted. The H2S yield was 65% under hydrolysis catalysis only, and 100% after the addition of H2.

[0047] Example 3

[0048] 3g(NH4)6Mo7O 24 ·4H2O was dissolved in 30 mL of deionized water, 6 g of La2O3 was added, and 2% NH3·H2O was added to adjust the pH to 8. The mixture was then dried in an oven at 120°C for 12 hours. The dried solid was placed in the center of a tube furnace and heated from room temperature to 400°C at a rate of 5°C / min in a 0.5% CS2 / 5% H2 mixed atmosphere, where it was maintained for 4 hours, to obtain catalytic hydrolysis-hydrogenation coupled desulfurization catalyst C.

[0049] The catalyst was passed through a 40-60 mesh sieve, and 0.2 g of the sieved catalyst was placed in a fixed-bed quartz tube reactor. 100 ppm COS, 30 ppm CS2, 5 vol% H2, N2 were used as carrier gases to simulate blast furnace gas. The total flow rate was controlled at 200 mL / min, and the reaction space velocity was 40,000 h -1 , relative humidity is 5%, and the catalyst is used to catalyze hydrolysis-hydrogenation coupling conversion of COS, CS2 and CH3SCH3 in blast furnace gas.

[0050] The catalyst performance was tested at 160°C. The conversion rates of COS, CS2 and CH3SCH3 of catalytic hydrolysis-hydrogenation coupled desulfurization catalyst C were 70%, 65% and 63% under hydrolysis catalysis alone. After the addition of H2, COS, CS2 and CH3SCH3 were completely converted. The H2S yield was 62% under hydrolysis catalysis alone and 100% after the addition of H2.

[0051] Test Example 1

[0052] 1.0 g of each of the catalytic hydrolysis-hydrogenation coupled desulfurization catalysts with reduced desulfurization efficiency from Examples 1-3 was soaked in 1 mol / L NaOH for 2 hours and heated to 200°C under a 60 mL / min N2 atmosphere for 2 hours. Simulated blast furnace gas was then introduced into a fixed-bed quartz tube reactor, and the conversion efficiencies of catalytic hydrolysis-hydrogenation coupled desulfurization catalysts A, B, and C for COS, CS2, and CH3SCH3 were calculated.

[0053] After five regenerations, the conversion efficiencies of the three catalysts for COS, CS2, and CH3SCH3 dropped below 95%.

[0054] Test Example 2

[0055] Figure 1 The following are the cycle performance curves of different catalytic hydrolysis-hydrogenation coupled desulfurization catalysts in the examples at a current density of 100 mA / g for 50 weeks. Figure 1 It can be seen from the discharge curve that after 50 cycles, the discharge specific capacities are 706.1 mAh / g, 652.3 mAh / g, and 503.1 mAh / g, respectively. Catalytic hydrolysis-hydrogenation coupled desulfurization catalyst A has the best charge and discharge cycle performance.

[0056] The composition and crystallinity of the catalyst were characterized by XRD. Figure 2XRD patterns of the prepared catalysts revealed that the diffraction peaks of all samples included the MoO2 (011), (-211), and (022) crystal planes and the MoS2 (002) crystal plane. The diffraction peaks of catalytic hydrolysis-hydrogenation coupled catalyst B were the weakest and significantly broadened, indicating a higher dispersion of the active phase. XRD characterization of catalytic hydrolysis-hydrogenation coupled desulfurization catalyst B, which had been recycled five times, revealed that the positions of the main crystal plane diffraction peaks (002, 011, 211, and 022) were essentially consistent before and after the reaction, with no new phase formation or peak position shifts, indicating that the catalyst's crystal structure remained intact.

[0057] The O vacancy and S vacancy contents of the three catalysts before the reaction were tested by electron paramagnetic resonance (EPR). Figure 3 In the EPR test, the three catalytic hydrolysis-hydrogenation coupled desulfurization catalysts all showed characteristic signals of g≈2.003 and g≈2.007, corresponding to oxygen vacancies (VO) and sulfur vacancies (VS), respectively. Figure 3 The signal intensity of catalytic hydrolysis-hydrogenation coupled desulfurization catalyst B is significantly higher than that of other materials. This is mainly due to the fact that the alumina support has a larger specific surface area, which increases the number of surface active sites, making MoS2 and MoO2 in the catalyst highly dispersed and rich in edge defect sites.

[0058] The MoO2-MoS2 composite catalyst was characterized by transmission electron microscopy (TEM) elemental analysis. Figure 4 (ad) show elemental mapping images of MoO2-MoS2. Elemental analysis results indicate that sulfur (S), oxygen (O), and molybdenum (Mo) are uniformly distributed in the catalyst, demonstrating the effective compounding of MoO2 and MoS2 and verifying the successful preparation of the MoO2-MoS2 composite catalyst.

[0059] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst, characterized in that: The following steps are involved: (1) dissolving ammonium molybdate tetrahydrate in water to form an ammonium molybdate solution, and then adding ammonia water dropwise to adjust the pH to 8-9; (2) drying the solution to obtain a solid; (3) The dried solid material is placed in the center of a tube furnace and heated and calcined in a mixed atmosphere of CS2 and H2 to obtain a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst.

2. The method for preparing a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst according to claim 1, characterized in that: Before adding ammonia water in step (1), M2O3 is also added; Wherein, the M2O3 is any one of Al2O3, La2O3 and Tm2O3.

3. The method for preparing a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst according to claim 2, characterized in that: In step (1), the mass ratio of ammonium molybdate tetrahydrate to M2O3 is 1-3:2-6.

4. The method for preparing a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst according to claim 1, characterized in that: In step (2), the drying temperature is 100-120° C. and the drying time is 10-12 hours.

5. The method for preparing a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst according to claim 1, characterized in that: In the mixed atmosphere of step (3), the volume proportion of CS2 is 0.5-1%, the volume proportion of H2 is 3-5%, and the rest is N2.

6. The method for preparing a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst according to claim 1, characterized in that: The calcination in step (3) is carried out by heating from room temperature to 400-450°C at a heating rate of 2-5°C / min and keeping the temperature for 3-4 hours.

7. Use of a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst prepared according to the method according to any one of claims 1 to 6 in removing organic sulfur from coal gas.

8. Use of a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst in removing organic sulfur from coal gas according to claim 7, characterized in that: The following steps are involved: 1) Blast furnace gas is passed into a fixed-bed quartz tube reactor, and a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst is used to catalytically hydrolyze and hydrogenate the organic sulfur in the blast furnace gas, thereby converting the difficult-to-remove organic sulfur into easily removable inorganic sulfur; 2) The coal gas after organic sulfur removal is sent to the hydrogen sulfide removal tower, where alkali-modified activated carbon is used to adsorb and purify the H2S contained in the coal gas to achieve precise H2S removal; 3) After desulfurization is completed, the catalytic hydrolysis-hydrogenation coupled desulfurization catalyst with reduced desulfurization efficiency is immersed in a 0.5-1 mol / L alkaline solution for 2-3 hours, and then heated to 180-200°C in a 60-80 mL / min N2 atmosphere for 2-3 hours to complete regeneration, and then recycled 3-5 times; The conversion rate of the hydrogenation-hydrolysis coupled desulfurization catalyst after regeneration can be increased to more than 95%. 4) The desulfurization catalyst after recycling is recycled and used as a negative electrode material for lithium-ion batteries after the excess S element is blown off with H2 and N2.

9. Use of a catalytic hydrolysis-hydrogenation coupled desulfurization catalyst in removing organic sulfur from coal gas according to claim 8, characterized in that: In step 1), the flow rate of blast furnace gas is 150-200 mL / min, and the reaction space velocity is 30,000-40,000 h -1 , relative humidity is 5%-10%RH.

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