Vanadium-molybdenum disulfide / aluminum oxide composite material, preparation method thereof and application of vanadium-molybdenum disulfide / aluminum oxide composite material in preparation of sulfur and hydrogen by catalyzing thermal cracking of hydrogen sulfide

Abstract

The invention discloses a vanadium-molybdenum disulfide / aluminum oxide composite material, a preparation method thereof and application of the vanadium-molybdenum disulfide / aluminum oxide composite material in preparation of sulfur and hydrogen by catalyzing thermal cracking of hydrogen sulfide, and belongs to the technical field of resource utilization of gas pollutants. The vanadium-molybdenum disulfide / alumina composite material is formed by loading amorphous vanadium-doped molybdenum disulfide nanoparticles on a porous alumina carrier, the composite material shows excellent catalytic stability and catalytic activity in the process of preparing hydrogen and sulfur by catalyzing thermal cracking of hydrogen sulfide, and the composite material is simple and efficient in preparation process, short in flow and suitable for industrial production. Reaction conditions are mild, and large-scale industrial production potential is achieved.

Description

Technical Field

[0001] The present invention relates to a catalytic material, in particular to a vanadium-molybdenum disulfide / aluminum oxide composite material, and also to a preparation method of the vanadium-molybdenum disulfide / aluminum oxide composite material, and to the application of the vanadium-molybdenum disulfide / aluminum oxide composite material in catalyzing the thermal cracking of hydrogen sulfide to prepare hydrogen and sulfur, belonging to the technical field of resource utilization of gaseous pollutants. Background Art

[0002] Hydrogen sulfide is a highly toxic and corrosive acidic gas that is widely present in industrial processes such as petrochemicals, natural gas purification, and coal processing. It not only causes serious corrosion to industrial equipment, but also pollutes the ecological environment and poses a major threat to human health. Even at extremely low concentrations, hydrogen sulfide can cause damage to the respiratory system, and in severe cases can lead to poisoning or even death. Therefore, the effective and harmless treatment of hydrogen sulfide has become an important topic in the field of chemical engineering and environmental protection. Traditional hydrogen sulfide treatment methods, such as the Claus process, can effectively convert hydrogen sulfide, but it not only causes a waste of hydrogen resources, but is also accompanied by the emission of harmful gases such as sulfur dioxide, and cannot achieve efficient resource recovery and green treatment.

[0003] In recent years, thermal catalytic cracking technology has been considered a promising solution for treating hydrogen sulfide, especially in terms of utilizing industrial waste heat and mature equipment. However, the catalysts of existing thermal catalytic cracking methods often have problems such as insufficient activity, poor stability, and limited resistance to sulfur poisoning, which seriously restricts the industrial application of this technology. Therefore, the development of long-lasting catalysts with high catalytic activity, thermal stability, and resistance to sulfur poisoning has become an important task at present.

[0004] MoS2 is far superior to many traditional transition metal oxides and sulfides due to its unique layered structure and abundant edge active sites, and has been widely used in the catalytic cracking reaction of hydrogen sulfide. However, the catalytic performance of pure MoS2 is easily affected by particle agglomeration at high temperature, resulting in a rapid decrease in its activity. The literature (“Constrained Growth of MoS2 Nanosheets within a Mesoporous Silica Shell and Its Effects on DefectSites and Catalyst Stability for H2S Decomposition, Kelvin Mingyao Kwok, et al., ACS Catalysis 2018 8 (1), 714-724.”) discloses the catalytic cracking of hydrogen sulfide by pure MoS2 nanoparticles, but its catalytic stability is poor, the cracking efficiency decreases by 19% within 4 hours, and the performance declines significantly. A Chinese patent (publication number CN104524934B) discloses a method for producing hydrogen and sulfur by microwave catalytic decomposition of hydrogen sulfide. The composite catalyst includes an active component (such as a transition metal sulfide), an optional carrier (such as γ-Al2O3) and a co-catalyst component (such as a perovskite catalyst). It produces sulfur and hydrogen while removing the toxic and harmful gas hydrogen sulfide, and can utilize hydrogen sulfide in the exhaust gas with maximum efficiency. However, the catalyst composition is complex, a co-catalyst is required, the cost is high, and the degradation efficiency of hydrogen sulfide is low. In addition, the high-temperature stability of the transition metal sulfide catalyst is poor, and it does not solve the technical problem. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the first object of the present invention is to provide a vanadium-molybdenum disulfide / alumina composite material composed of amorphous vanadium-doped molybdenum disulfide nanoparticles loaded on a porous alumina carrier. The composite material has good thermal stability, abundant and uniformly distributed catalytic active sites, and exhibits high catalytic activity, so that it can maintain high catalytic performance for a long time under high temperature conditions.

[0006] The second object of the present invention is to provide a method for preparing a vanadium-molybdenum disulfide / aluminum oxide composite material, which is simple to operate, has mild conditions, is low in cost, and has good industrial applicability.

[0007] The third object of the present invention is to provide an application of a vanadium-molybdenum disulfide / alumina composite material in catalyzing the thermal cracking of hydrogen sulfide to prepare hydrogen and sulfur. The catalytic material exhibits high catalytic cracking efficiency and stable performance for hydrogen sulfide gas, and is particularly suitable for use in an industrial process of catalyzing the high-temperature cracking of hydrogen sulfide to prepare hydrogen and sulfur.

[0008] In order to achieve the above technical objectives, the present invention provides a vanadium-molybdenum disulfide / alumina composite material, which is composed of amorphous vanadium-doped molybdenum disulfide nanoparticles loaded on a porous alumina carrier; the molar amount of vanadium and molybdenum in the amorphous vanadium-doped molybdenum disulfide nanoparticles is 1-50% of the molar amount of alumina in the porous alumina carrier; the molar amount of vanadium in the amorphous vanadium-doped molybdenum disulfide nanoparticles is 1-50% of the molar amount of molybdenum.

[0009] The active component of the vanadium-molybdenum disulfide / alumina composite material of the present invention is vanadium-doped molybdenum disulfide, and the carrier is porous alumina. The porous alumina not only has strong thermal stability and corrosion resistance, and can withstand the high temperature environment and the strong corrosion environment of hydrogen sulfide gas in the thermal cracking process, but also has a high specific surface area and a developed pore structure, and there is a strong interaction between the alumina and the molybdenum disulfide, which can achieve high dispersion and stable loading of the vanadium-doped molybdenum disulfide active component, can expose more catalytic active sites, and can effectively prevent the agglomeration of molybdenum disulfide particles under high temperature conditions, thereby showing long-term stable high catalytic activity. At the same time, its porous structure and high specific surface area are also conducive to the adsorption of hydrogen sulfide gas and promote its thermal decomposition process. In vanadium-doped molybdenum disulfide, vanadium is doped in the lattice of molybdenum disulfide in an amorphous form, which can significantly improve the catalytic performance by enhancing the sulfur vacancy density and optimizing the generation of unsaturated molybdenum sites. The synergistic effect of vanadium and molybdenum disulfide can optimize the distribution of catalytic active sites of molybdenum disulfide, enabling it to exhibit higher efficiency and stability in the hydrogen sulfide cracking reaction.

[0010] The molar amount of vanadium and molybdenum in the amorphous vanadium-doped molybdenum disulfide nanoparticles of the present invention is 1 to 50% of the molar amount of aluminum oxide in the alumina carrier. A low vanadium-molybdenum loading will result in fewer catalytically active components and a low efficiency in treating high-concentration hydrogen sulfide. Too high a loading will reduce the specific surface area of ​​the catalyst and reduce the exposure of active components. Secondly, too high a vanadium-molybdenum loading will also lead to catalyst waste and increased catalyst production costs. The molar amount of vanadium and molybdenum in the amorphous vanadium-doped molybdenum disulfide nanoparticles is further preferably 10 to 30% of the molar amount of aluminum oxide in the alumina carrier.

[0011] The molar amount of vanadium in the amorphous vanadium-doped molybdenum disulfide nanoparticles of the present invention is 1 to 50% of the molar amount of molybdenum. As the amount of amorphous vanadium doped in molybdenum disulfide increases, the concentration of unsaturated molybdenum sites and sulfur vacancies in the catalyst increases, which is beneficial to improving the catalytic performance of the catalyst. However, if the doping amount of amorphous vanadium is further increased, the improvement in the catalytic performance of the catalyst will not be further significantly increased. The molar amount of vanadium in the amorphous vanadium-doped molybdenum disulfide nanoparticles is further preferably 5 to 25% of the molar amount of molybdenum.

[0012] The present invention also provides a method for preparing a vanadium-molybdenum disulfide / aluminum oxide composite material, which comprises the following steps:

[0013] (1) mixing a porous alumina carrier and a sulfur source with a molybdenum-vanadium mixed metal salt solution to form a sulfidation reaction solution;

[0014] (2) transferring the sulfidation reaction liquid to a high-pressure reactor for hydrothermal reaction to obtain a precursor material;

[0015] (3) Drying and calcining the precursor material under oxygen-free conditions to obtain the product.

[0016] The key to the preparation of the vanadium-molybdenum disulfide / alumina composite material of the present invention is to realize a step-by-step, orderly and efficient sulfurization process of the metal through a three-step heat treatment of "hydrothermal-drying-calcination". This process not only ensures the in-situ loading of molybdenum sulfide on the surface of porous alumina, realizes stable bonding and uniform dispersion, but also utilizes the vanadium element to regulate the structural defects and active sites of molybdenum disulfide, ultimately forming highly active nano-vanadium-molybdenum disulfide particles.

[0017] As a preferred solution, the molybdenum ion concentration in the molybdenum-vanadium mixed metal salt solution is 0.001~1 mol / L.

[0018] As a preferred embodiment, the molar ratio of vanadium ions to molybdenum ions in the molybdenum-vanadium mixed metal salt solution is 1-50:100.

[0019] As a preferred embodiment, the ratio of the molar amount of alumina in the porous alumina carrier to the total molar amount of vanadium ions and molybdenum ions in the molybdenum-vanadium mixed metal salt solution is 100:1-50.

[0020] As a preferred solution, the ratio of the molar amount of sulfur element in the sulfur source to the total molar amount of vanadium ions and molybdenum ions in the molybdenum-vanadium mixed metal salt solution is 2 to 6: 1. By using an appropriate excess of sulfur source, metal ions can be fully converted into metal sulfides, and the excess sulfur can prevent material oxidation and sulfur volatilization loss at high temperatures in subsequent heat treatment reactions.

[0021] As a preferred solution, the porous alumina carrier includes at least one of spherical porous alumina, fibrous porous alumina, and amorphous porous alumina. The porous alumina material is preferably a material having a high specific surface area and a rich pore structure, which can improve the dispersibility and loading stability of vanadium-molybdenum disulfide, and is conducive to the adsorption and enrichment of hydrogen sulfide gas, and promotes the pyrolysis process of hydrogen sulfide gas.

[0022] As a preferred solution, the molybdenum-vanadium mixed metal salt solution contains at least one molybdenum salt selected from ammonium dimolybdate, ammonium tetramolybdate, ammonium heptamolybdate, and ammonium tetrathiomolybdate. The preferred molybdenum salts are all common molybdenum salts with good water solubility.

[0023] As a preferred solution, the molybdenum-vanadium mixed metal salt solution contains at least one vanadium salt selected from ammonium polyvanadate and ammonium metavanadate. The preferred vanadium salts are all common vanadium salts with good water solubility.

[0024] As a preferred solution, the sulfur source includes at least one of sodium sulfide, thiourea, sodium thiosulfate, and thioacetamide. The preferred sulfur source is a common water-soluble sulfur-containing compound.

[0025] As a preferred solution, the conditions of the hydrothermal reaction are: temperature of 60-200°C and time of 1-24h. The preferred hydrothermal reaction conditions are conducive to the in-situ generation of molybdenum disulfide on the porous alumina support, and improve the bonding strength between molybdenum disulfide and the porous alumina support.

[0026] As a preferred solution, the drying conditions are: temperature of 30-120° C. and time of 1-48 h.

[0027] As a preferred solution, the calcination conditions are: temperature of 400-1000° C. and time of 1-24 h.

[0028] Through heat treatment processes such as drying and calcination, not only can the molybdenum be further thoroughly sulfurized, but the crystal structure of molybdenum disulfide can also be effectively regulated, so that low-crystallinity molybdenum disulfide is converted into high-crystallinity, ordered nano-molybdenum disulfide crystals. Under high temperature conditions, it is beneficial for excess sulfur to sublimate and expose more active sites, and it is also beneficial for vanadium doping to increase the formation of unsaturated molybdenum sites, further improving the catalytic performance of the catalytic material.

[0029] The oxygen-isolating environment of the present invention is under a protective atmosphere (such as nitrogen, argon, helium) or vacuum.

[0030] The present invention also provides an application of a vanadium-molybdenum disulfide / aluminum oxide composite material, which is used for catalyzing the thermal cracking of hydrogen sulfide to prepare sulfur and hydrogen. The present invention also provides a vanadium-molybdenum disulfide / aluminum oxide composite material that has a highly efficient catalytic thermal cracking effect on hydrogen sulfide under high temperature conditions, especially under common industrial high temperature conditions (such as above 600°C), showing excellent hydrogen sulfide catalytic thermal cracking efficiency, which is due to the active sites of the molybdenum disulfide structure regulated by vanadium doping and the enhanced thermal stability of the alumina carrier.

[0031] As a preferred solution, the mass volume ratio of the vanadium-molybdenum disulfide / aluminum oxide composite material to hydrogen sulfide gas is 0.1-10 mg / mL.

[0032] As a preferred solution, the volume concentration of the hydrogen sulfide gas is 0.01-100%.

[0033] As a preferred solution, the temperature range of the thermal cracking is 400-1500° C. As the temperature increases, the thermal cracking efficiency of the vanadium-molybdenum disulfide / alumina composite material for hydrogen sulfide first increases and then tends to stabilize, so the further preferred thermal cracking temperature range is 800-1000° C.

[0034] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0035] The active component of the vanadium-molybdenum disulfide / alumina composite material of the present invention, amorphous vanadium-doped molybdenum disulfide nanoparticles, has excellent dispersibility and stable bonding on the surface of a porous alumina carrier, has strong thermal stability and resistance to hydrogen sulfide corrosion, and has high activity in catalyzing the thermal decomposition of hydrogen sulfide.

[0036] The preparation method of the vanadium-molybdenum disulfide / aluminum oxide composite material of the present invention is simple to operate, has mild conditions, and has low cost, and is suitable for large-scale industrial production.

[0037] Compared with existing catalytic materials, the vanadium-molybdenum disulfide / alumina composite material of the present invention optimizes the crystal structure of molybdenum disulfide by doping with amorphous vanadium, forms more active sites, and the confinement effect of the porous alumina carrier effectively prevents the high-temperature agglomeration behavior of molybdenum disulfide, thereby improving the overall catalytic efficiency.

[0038] The vanadium-molybdenum disulfide / aluminum oxide composite catalyst of the present invention is suitable for various hydrogen sulfide treatment processes, especially in the context of the rapid development of the hydrogen production industry, and has great market prospects. Its economy and environmental protection enable it to replace the traditional desulfurization process and expand into a multifunctional catalytic material, providing a new path for efficient hydrogen production and comprehensive resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a schematic diagram of the process flow for preparing the vanadium-molybdenum disulfide / aluminum oxide composite material.

[0040] Figure 2 This is a schematic diagram of the hydrogen sulfide cracking efficiency of the vanadium-molybdenum disulfide / alumina composite material prepared in Example 1, Example 2, and Example 3 of the present invention.

[0041] Figure 3 Schematic diagram of a long-term hydrogen sulfide cracking test of the vanadium-molybdenum disulfide / aluminum oxide composite material prepared in Example 2 of the present invention.

[0042] Figure 4 This is a schematic diagram of the hydrogen sulfide cracking efficiency at different temperatures of the vanadium-molybdenum disulfide / aluminum oxide composite material prepared in Example 2 of the present invention.

[0043] Figure 5This is a schematic diagram of the hydrogen sulfide cracking efficiency of the materials prepared in Comparative Examples 1, 2 and 3 of the present invention.

[0044] Figure 6 This is the XRD spectrum of the vanadium-molybdenum disulfide / aluminum oxide composite material prepared in Example 1, Example 2, and Example 3 of the present invention.

[0045] Figure 7 This is a scanning electron microscope image of the vanadium-molybdenum disulfide / aluminum oxide composite material prepared in Example 2.

[0046] Figure 8 This is the R space fitting curve of the vanadium element Fourier transform extended X-ray absorption fine structure (EXAFS) of the vanadium-molybdenum disulfide / aluminum oxide composite material prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present invention will be described in detail in conjunction with the accompanying drawings. The embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, other embodiments that can be obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. The technical solutions between the various embodiments can be combined with each other, but it must be ensured that they are implemented under the premise that ordinary technicians in this field can do so. If there is a contradiction or inability to implement the technical solutions, it should be considered that the combination is not established and is not within the protection scope of the present invention. The numerical range in the embodiment, unless otherwise specified, each endpoint and any value between them can be selected. The technical and scientific terms used in the present invention are consistent with the understanding of the prior art by those skilled in the art, and the prior art methods similar or equivalent to the methods, equipment, and materials described in the embodiments can also be used. The following specific embodiments are preferred embodiments, and ordinary technicians can improve and embellish them without departing from the principle, and these improvements also belong to the protection scope of the present invention. The specific embodiments do not limit the protection scope of the present invention, and changing the implementation does not affect the protection scope of the main claim.

[0048] The following cases were all conducted in a high-temperature fluidized bed reactor. During the experiment, 20 mg of the catalyst was weighed and placed in a quartz column with an inner diameter of 3 mm, and the hydrogen sulfide cracking performance test was carried out in the temperature range of 600°C to 1000°C. The experimental conditions were: the flow rate of the flue gas containing hydrogen sulfide was set to 20 mL / min, the hydrogen sulfide concentration was 1%, and the balance gas was nitrogen. The change in hydrogen sulfide concentration was monitored in real time by an online hydrogen sulfide gas analyzer to evaluate the cracking performance and stability of the catalyst.

[0049] Example 1

[0050] Ammonium molybdate tetrahydrate (0.260 g) and ammonium metavanadate (0.009 g) were dissolved in 40 mL of deionized water, and then 1 g of amorphous porous alumina was weighed, 20 mL of ethanol was added as a dispersant, and the mixture was fully mixed with the above mixed solution, and then 0.5 g of thioacetamide was added to form a sulfidation reaction solution. The mixed solution was transferred to an autoclave and hydrothermally treated at 180 ° C for 24 hours. After the reaction was completed, it was naturally cooled to room temperature, the black precipitate was collected by filtration, and washed alternately with ethanol and deionized water to obtain a precursor material. The precursor material was placed in a vacuum environment, dried at 60 ° C for 10 hours, and then transferred to a tubular furnace, heated to 800 ° C at a heating rate of 5 ° C / min under nitrogen protection, and kept warm for 2 hours, and finally cooled naturally to obtain a vanadium-molybdenum disulfide / alumina composite material.

[0051] The vanadium-molybdenum disulfide / alumina composite material obtained in Example 1 has a theoretical molar ratio of vanadium / molybdenum ions of 5:95, which is recorded as AMV1. AMV1 was tested for hydrogen sulfide cracking performance at 800°C, and the cracking efficiency reached 65% after stabilization, showing excellent catalytic activity and stability, proving its application potential in high-temperature hydrogen sulfide treatment.

[0052] Example 2

[0053] Ammonium molybdate tetrahydrate (0.248 g) and ammonium metavanadate (0.018 g) were dissolved in 40 mL of deionized water, and then 1 g of amorphous porous alumina was weighed, 20 mL of ethanol was added as a dispersant, and it was fully mixed with the above mixed solution, and then 0.5 g of thioacetamide was added to form a sulfidation reaction solution. The mixed solution was transferred to an autoclave and hydrothermally treated at 180 ° C for 24 hours. After the reaction was completed, it was naturally cooled to room temperature, and the black precipitate was collected by filtration and washed alternately with ethanol and deionized water to obtain a precursor material. The precursor material was placed in a vacuum environment, dried at 60 ° C for 10 hours, and then transferred to a tubular furnace, heated to 800 ° C at a heating rate of 5 ° C / min under nitrogen protection, and kept warm for 2 hours, and finally cooled naturally to obtain a vanadium-molybdenum disulfide / alumina composite material.

[0054] The vanadium-molybdenum disulfide / aluminum oxide composite material obtained in Example 2 has a theoretical molar ratio of vanadium to molybdenum ions of 10:90, and is labeled as AMV2. The AMV2 sample was tested for hydrogen sulfide cracking performance at 800°C, and the cracking efficiency reached 72% after stabilization, which is further improved than that of AMV1.

[0055] Example 3

[0056] Ammonium molybdate tetrahydrate (0.220 g) and ammonium metavanadate (0.036 g) were dissolved in 40 mL of deionized water, and then 1 g of amorphous porous alumina was weighed, 20 mL of ethanol was added as a dispersant, and the mixture was fully mixed with the above mixed solution, and then 0.5 g of thioacetamide was added to form a sulfidation reaction solution. The mixed solution was transferred to an autoclave and hydrothermally treated at 180 ° C for 24 hours. After the reaction was completed, it was naturally cooled to room temperature, and the black precipitate was collected by filtration and washed alternately with ethanol and deionized water to obtain a precursor material. The precursor material was placed in a vacuum environment, dried at 60 ° C for 10 hours, and then transferred to a tubular furnace, heated to 800 ° C at a heating rate of 5 ° C / min under nitrogen protection, and kept warm for 2 hours, and finally cooled naturally to obtain a vanadium-molybdenum disulfide / alumina composite material.

[0057] The vanadium-molybdenum disulfide / aluminum oxide composite material obtained in Example 3 has a theoretical molar ratio of vanadium to molybdenum ions of 20:80, and is labeled AMV3. The AMV3 sample was tested for hydrogen sulfide cracking performance at 800°C, and the cracking efficiency reached 69% after stabilization, which was slightly lower than that of AMV2.

[0058] Example 4

[0059] Ammonium molybdate tetrahydrate (0.248 g) and ammonium metavanadate (0.018 g) were dissolved in 40 mL of deionized water, and then 1 g of amorphous porous alumina was weighed, 20 mL of ethanol was added as a dispersant, and it was fully mixed with the above mixed solution, and then 0.5 g of thioacetamide was added to form a sulfidation reaction solution. The mixed solution was transferred to an autoclave and hydrothermally treated at 200 ° C for 24 hours. After the reaction was completed, it was naturally cooled to room temperature, and the black precipitate was collected by filtration and washed alternately with ethanol and deionized water to obtain a precursor material. The precursor material was placed in a vacuum environment, dried at 60 ° C for 10 hours, and then transferred to a tubular furnace, heated to 900 ° C at a heating rate of 5 ° C / min under nitrogen protection, and kept warm for 2 hours, and finally cooled naturally to obtain a vanadium-molybdenum disulfide / alumina composite material.

[0060] The vanadium-molybdenum disulfide / aluminum oxide composite material obtained in Example 4 has a theoretical molar ratio of vanadium to molybdenum ions of 10:90, and is labeled as AMV4. The AMV4 sample was tested for hydrogen sulfide cracking performance at 800°C, and the cracking efficiency reached 72% after stabilization, showing the same catalytic performance as AMV2.

[0061] Example 5

[0062] The vanadium-molybdenum disulfide / aluminum oxide composite material of Example 2 was subjected to a long-term cracking performance test at 800°C. The results are as follows: Figure 3The hydrogen sulfide cracking efficiency of AMV2 was maintained at 72% within 10 hours, proving that it has good long-term cracking stability. In addition, the hydrogen sulfide cracking efficiency of AMV2 was evaluated at different temperatures. Figure 4 At 600°C, the cracking efficiency is 50%; at 1000°C, the cracking efficiency rises to 75%, showing high-efficiency catalytic performance over a wide operating temperature range.

[0063] Comparative Example 1

[0064] 2.0 g of polyether P123 was dissolved in 40 mL of ethanol, and 3.0 mL of 67% nitric acid and 4.0 g of aluminum isopropoxide were added under vigorous stirring. The mixture was covered with a polyethylene film and continued to be stirred at room temperature for about 12 hours to ensure thorough mixing. Then, the mixture was placed in an oven at 60°C and heated for 48 hours to fully evaporate the solvent. The dried solid precursor was calcined at 800°C for 2 hours with a heating rate of 2°C / min to finally prepare an amorphous porous alumina material.

[0065] The alumina material prepared in this comparative example 1 was subjected to a hydrogen sulfide cracking performance test at 800° C. The test showed that the hydrogen sulfide cracking efficiency was only 50%. Compared with the vanadium-molybdenum disulfide / alumina composite material prepared in Example 2, this comparative example exhibited a lower catalytic performance, indicating that only using the carrier alumina as a catalyst could not effectively improve the hydrogen sulfide cracking efficiency.

[0066] Comparative Example 2

[0067] Ammonium molybdate tetrahydrate (0.278 g) was dissolved in 40 mL of deionized water, 20 mL of ethanol was added as a dispersant, and the mixture was fully mixed with the above-mentioned mixed solution, followed by the addition of 0.5 g of thioacetamide to form a sulfidation reaction solution. The mixed solution was transferred to a high-pressure reactor and subjected to hydrothermal treatment at 200 ° C for 24 hours. After the reaction was completed, it was naturally cooled to room temperature, the black precipitate was collected by filtration, and washed alternately with ethanol and deionized water to obtain a precursor material. The precursor material was placed in a vacuum environment, dried at 60 ° C for 10 hours, and then transferred to a tubular furnace, heated to 800 ° C at a heating rate of 5 ° C / min under nitrogen protection, and kept warm for 2 hours, and finally cooled naturally to obtain a molybdenum disulfide material.

[0068] The molybdenum disulfide material obtained in this comparative example 2 was tested for hydrogen sulfide cracking performance at 800°C. The initial cracking efficiency was high, but the cracking efficiency gradually decreased to 57%, showing an obvious catalytic deactivation trend. The decline in performance is related to the thermal stability of molybdenum disulfide itself and the reduction of active sites during hydrogen sulfide cracking. In addition, vanadium or aluminum oxide was not introduced as a synergistic component, resulting in its catalytic performance being significantly lower than that of the composite material in Example 2. This further illustrates the important role of vanadium elements and aluminum oxide matrix in improving the thermal stability and catalytic activity of composite catalytic materials.

[0069] Comparative Example 3

[0070] Ammonium molybdate tetrahydrate (0.278 g) was dissolved in 40 mL of deionized water, and then 1 g of amorphous porous alumina was weighed, 20 mL of ethanol was added as a dispersant, and it was fully mixed with the above mixed solution, and then 0.5 g of thioacetamide was added to form a sulfidation reaction solution. The mixed solution was transferred to an autoclave and hydrothermally treated at 200 ° C for 24 hours. After the reaction was completed, it was naturally cooled to room temperature, and the black precipitate was collected by filtration and washed alternately with ethanol and deionized water to obtain a precursor material. The precursor material was placed in a vacuum environment, dried at 60 ° C for 10 hours, and then transferred to a tubular furnace, heated to 800 ° C at a heating rate of 5 ° C / min under nitrogen protection, and kept warm for 2 hours, and finally cooled naturally to obtain a molybdenum disulfide / alumina composite material.

[0071] The molybdenum disulfide / aluminum oxide composite material obtained in this comparative example 3 has a molybdenum disulfide loading of 20 wt%. The hydrogen sulfide cracking performance test was carried out at 800 ° C, and the cracking efficiency was only 62%, which was significantly lower than the vanadium-molybdenum disulfide / aluminum oxide composite material in Example 2. Although the sample showed a certain catalytic activity, the catalytic performance was limited due to the lack of the introduction of vanadium as an auxiliary active component. This shows that the introduction of vanadium can significantly improve the synergistic effect and overall performance of the catalytic material.

[0072] The crystal structures of the materials prepared in Example 1, Example 2 and Example 3 were analyzed by XRD. Figure 6 As shown. At 37.7 ° , 45.9 ° , 94.7 ° The diffraction peak at 14.4 ° , 32.7 ° , 39.6 ° , 58.4 °The diffraction peaks at are consistent with the (002), (100), (103), and (110) crystal planes of MoS2. No peaks of aggregated MoS2 were observed in the catalyst, indicating that alumina effectively restricts the agglomeration behavior of MoS2 nanosheets and prevents them from combining into aggregated MoS2 during high temperature processes. The addition of vanadium to MoS2 has no effect on the crystal structure of MoS2. No vanadium sulfide-related crystalline phases were detected in AM1, AM2, and AMV3, indicating that vanadium exists in the MoS2 lattice in an amorphous form, which is conducive to the formation of more sulfur vacancies, thereby improving the hydrogen sulfide cracking performance of the catalyst.

[0073] The vanadium-molybdenum disulfide / aluminum oxide composite material prepared in Example 2 was subjected to SEM analysis. The results are as follows: Figure 7 As shown in Figure 2, MoS2 is stacked on the surface of alumina in the form of three-dimensional sheets. This loading form exposes more active components and effectively enhances the catalytic performance.

[0074] The vanadium element Fourier transform extended X-ray absorption fine structure (EXAFS) R spatial fitting curve of the vanadium-molybdenum disulfide / aluminum oxide composite material prepared in Example 2 is as follows: Figure 8 As shown. Based on the Fourier transform extended X-ray absorption fine structure (EXAFS) R space fitting, there is only a single significant main scattering peak in the local coordination environment of vanadium. The fitting results show that the peak is completely attributed to the first coordination shell interaction (VS bond) between vanadium and sulfur atoms, and the corresponding average coordination number is 3.5±0.4. It was further verified by full spectrum fitting and multi-shell structure model, and no scattering signals related to VV, VO or V-Mo were found. The above shows that the coordination environment of vanadium is dominated by sulfur atoms, excluding the possibility of oxidation state (VO bond) or vanadium-molybdenum hybrid structure. Vanadium atoms are highly dispersed and embedded in the material matrix in a completely isolated single atom form, and no vanadium metal clusters or vanadium metal sulfides are formed.

[0075] The contents disclosed above are only preferred embodiments of the present invention, which are intended to better illustrate the technical solutions of the present invention, rather than limiting the scope of protection of the claims of the present invention. A person of ordinary skill in the art can understand and implement all or part of the processes of the above embodiments, and make equivalent transformations or improvements within the technical concept and scope of the claims of the present invention, and these transformations or improvements still fall within the scope of protection of the present invention. All equivalent structural transformations made according to the contents of this specification and the drawings under the technical concept of the present invention, or solutions directly or indirectly applied to other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A vanadium-molybdenum disulfide / aluminum oxide composite material, characterized in that: It is composed of amorphous vanadium-doped molybdenum disulfide nanoparticles loaded on a porous alumina support; The molar amount of vanadium and molybdenum in the amorphous vanadium-doped molybdenum disulfide nanoparticles is 1 to 50% of the molar amount of alumina in the porous alumina support; The molar amount of vanadium element in the amorphous vanadium-doped molybdenum disulfide nanoparticles is 1-50% of the molar amount of molybdenum element.

2. The method for preparing a vanadium-molybdenum disulfide / aluminum oxide composite material according to claim 1, characterized in that: The following steps are involved: (1) mixing a porous alumina carrier and a sulfur source with a molybdenum-vanadium mixed metal salt solution to form a sulfidation reaction solution; (2) transferring the sulfidation reaction liquid to a high-pressure reactor for hydrothermal reaction to obtain a precursor material; (3) Drying and calcining the precursor material under oxygen-free conditions to obtain the product.

3. The method for preparing a vanadium-molybdenum disulfide / aluminum oxide composite material according to claim 2, characterized in that: The molybdenum ion concentration in the molybdenum-vanadium mixed metal salt solution is 0.001-1 mol / L; The molar ratio of vanadium ions to molybdenum ions in the molybdenum-vanadium mixed metal salt solution is 1 to 50:100; The ratio of the molar amount of aluminum oxide in the porous aluminum oxide carrier to the total molar amount of vanadium ions and molybdenum ions in the molybdenum-vanadium mixed metal salt solution is 100:1-50; The ratio of the molar amount of sulfur element in the sulfur source to the total molar amount of vanadium ions and molybdenum ions in the molybdenum-vanadium mixed metal salt solution is 2-6:

1.

4. The method for preparing a vanadium-molybdenum disulfide / aluminum oxide composite material according to claim 2, characterized in that: The porous alumina carrier includes at least one of spherical porous alumina, fibrous porous alumina, and amorphous porous alumina; The molybdenum-vanadium mixed metal salt solution contains at least one molybdenum salt selected from the group consisting of ammonium dimolybdate, ammonium tetramolybdate, ammonium heptamolybdate, and ammonium tetrathiomolybdate; The molybdenum-vanadium mixed metal salt solution contains at least one vanadium salt selected from ammonium polyvanadate and ammonium metavanadate; The sulfur source includes at least one of sodium sulfide, thiourea, sodium thiosulfate and thioacetamide.

5. The method for preparing a vanadium-molybdenum disulfide / aluminum oxide composite material according to any one of claims 2 to 4, characterized in that: The conditions of the hydrothermal reaction are: temperature of 60-200° C. and time of 1-24 h.

6. The method for preparing a vanadium-molybdenum disulfide / aluminum oxide composite material according to any one of claims 2 to 4, characterized in that: The drying conditions are: temperature of 30-120° C. and time of 1-48 h.

7. The method for preparing a vanadium-molybdenum disulfide / aluminum oxide composite material according to any one of claims 2 to 4, characterized in that: The calcination conditions are: temperature of 400-1000° C. and time of 1-24 h.

8. The use of a vanadium-molybdenum disulfide / aluminum oxide composite material according to claim 1, characterized in that: Used for catalytic thermal cracking of hydrogen sulfide to produce sulfur and hydrogen.

9. The use of a vanadium-molybdenum disulfide / aluminum oxide composite material according to claim 8, characterized in that: The mass volume ratio of the vanadium-molybdenum disulfide / aluminum oxide composite material to hydrogen sulfide gas is 0.1-10 mg / mL; The volume concentration of the hydrogen sulfide gas is 0.01-100%; The temperature range of the thermal cracking is 400-1500°C.

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