A catalyst for the synthesis of methanethiol from COS / H2S and its preparation method

Abstract

The application discloses a catalyst for catalyzing COS / H2S to synthesize methyl mercaptan and a preparation method thereof, and belongs to the technical field of catalysts. The catalyst is spherical alumina, and the preparation method comprises the following steps: dissolving alumina precursors, a sulfate and a precipitating agent in water to obtain a mixed solution, and performing a hydrothermal reaction by heating; and after the hydrothermal reaction is completed, cooling, filtering, washing, drying and calcining are performed to obtain the spherical alumina catalyst. The spherical alumina catalyst is prepared by a hydrothermal and calcination method, the catalyst has a unique microsphere structure and acid-base sites, can provide more active centers and a better reaction environment, greatly enhances the activity and selectivity of COS / H2S in synthesizing methyl mercaptan, and thus has a better catalytic effect in a reaction related to COS / H2S cooperative removal and resource synthesis of methyl mercaptan.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a catalyst for the synthesis of methanethiol from COS / H2S and a method for its preparation. Background Technology

[0002] Traditional coal combustion methods produce large amounts of oxidized sulfur species (SO₄). x New clean coal utilization technologies (such as coal-to-oil, coal-to-olefins, and coal-to-methanol) are more economical, cleaner, and lower carbon-carbon, effectively avoiding SO2 emissions. x However, the clean utilization of coal and the production and processing of oil and natural gas inevitably generate large amounts of sulfur-containing pollutants such as hydrogen sulfide (H2S) and carbonyl sulfide (COS), which pose a significant threat to human health and the environment. Furthermore, methanethiol, as an important chemical raw material, is widely used in pharmaceuticals, synthetic pesticides, feed additives, food, and synthetic materials industries. Therefore, removing various sulfur-containing species generated during clean coal utilization (such as coal gasification) and other chemical production processes, and synergistically catalytically converting two-component sulfur-containing pollutants (COS / H2S) to synthesize methanethiol, can become a new approach to achieve clean coal utilization and alleviate smog pollution. Currently, the directional conversion behavior and mechanism of sulfur-containing pollutants are not yet clear. Therefore, it is essential to elucidate the reaction mechanism of methanethiol synthesis under this reaction atmosphere from macroscopic to microscopic levels, and further develop catalysts with high catalytic performance to improve the COS conversion rate and CH3SH selectivity of this reaction. In this process, both types of sulfur-containing pollutants are treated simultaneously, and methanethiol, a chemical product with high added value, is synthesized directionally.

[0003] Currently, research on the removal of reducing sulfur species (H2S / COS, etc.) mainly employs physical, chemical, and biological methods to treat single sulfur-containing species. For the removal of odorous H2S, methods primarily include dilution masking, solution absorption, adsorption, biological methods, Claus / modified Claus processes, photoelectrocatalysis, and catalytic cracking. Among these, the most widely used and mature H2S treatment technology in industry is the Claus / modified Claus process, which mainly obtains sulfur or sulfuric acid through catalytic oxidation of H2S, but the resulting products generally have low added value. Furthermore, research on COS removal both domestically and internationally mainly employs adsorption, catalytic hydrolysis, and catalytic hydrogenation techniques. Catalytic hydrolysis has become the primary method for COS removal due to its ability to achieve highly efficient COS conversion at ambient temperature and pressure. However, regardless of the method used to treat reduced sulfur species, they ultimately convert to H2S, further producing sulfur (900-1500 yuan / ton) or sulfuric acid (300-500 yuan / ton). This results in low economic benefits and low added value, making it difficult to cover the manufacturing and operating costs of desulfurization equipment and instruments. Therefore, the synergistic removal of two-component sulfur-containing pollutants (COS / H2S) to prepare methanethiol can not only effectively remove sulfur species such as H2S, but also yield a high-value-added product—methanethiol (20,000-100,000 yuan / ton), which is of great significance both environmentally and economically.

[0004] The catalysts used in the traditional synthesis of methanethiol are mainly alkali metal-promoted Mo / W / V catalysts. These catalysts require the active ingredient to be supported on a carrier, resulting in complex preparation methods, high raw material costs, and room for improvement in catalytic efficiency (conversion and selectivity). Therefore, it is essential to find catalysts with simple composition, easy preparation methods, and good catalytic performance. Summary of the Invention

[0005] The purpose of this invention is to provide a catalyst for the synthesis of methanethiol from COS / H2S and its preparation method, so as to solve the above-mentioned problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of the present invention is a method for preparing a spherical alumina catalyst, comprising the following steps: dissolving an alumina precursor, a sulfate and a precipitant in water to obtain a mixed solution, heating to carry out a hydrothermal reaction; after the hydrothermal reaction is completed, cooling, filtering, washing, drying and calcining to obtain the spherical alumina (Al2O3) catalyst.

[0008] Spherical alumina has a larger surface area, which helps to improve the reactivity and adsorption of the material.

[0009] The reaction principle of this invention is as follows: under high temperature and pressure, and with the promotion of sulfate ions, Al3+ Amorphous aluminum hydroxide spheres are precipitated by alternating hydrolysis and condensation of urea and precipitant. During the process of the solution reaching equilibrium, crystal nuclei undergo secondary nucleation and growth. After washing, drying and calcination, spherical aluminum oxide is obtained.

[0010] The spherical alumina prepared by the method of the present invention has a unique structure and acid-base sites, which can provide more active centers and a better reaction environment, thereby effectively promoting the synthesis of methanethiol.

[0011] Furthermore, the alumina precursor is aluminum nitrate.

[0012] Furthermore, the aluminum nitrate is aluminum nitrate containing water of crystallization.

[0013] Aluminum nitrate is highly water-soluble and readily dissolves in water. Using aluminum nitrate as a precursor in an aqueous phase makes the synthesis reaction more convenient and allows for better control of reaction conditions and product morphology.

[0014] Furthermore, the sulfate is potassium sulfate, sodium sulfate, or ammonium sulfate.

[0015] Furthermore, the precipitant is urea.

[0016] Furthermore, the ratio of the alumina precursor, sulfate, precipitant, and water is 0.02–0.06 mol: 0.02–0.06 mol: 0.06–0.10 mol: 150–200 mL.

[0017] Dissolve the alumina precursor, sulfate, and precipitant in water and stir for 20–40 minutes.

[0018] Furthermore, the filtration specifically refers to filtration until the TDS value of the filtrate is <10.

[0019] Furthermore, the washing process specifically involves alternating between washing with water and ethanol.

[0020] Furthermore, the hydrothermal reaction is carried out at a temperature of 150–200°C for a duration of 2–6 hours.

[0021] Furthermore, the drying temperature is 60–100°C, and the time is 6–12 hours.

[0022] Furthermore, the calcination temperature is 500–600°C, and the time is 2–4 hours.

[0023] Furthermore, the roasting time is preferably 2 hours.

[0024] The second technical solution of the present invention: a spherical alumina catalyst prepared according to the above preparation method.

[0025] The third technical solution of the present invention: the application of the above-mentioned spherical alumina catalyst in the catalytic synthesis of methanethiol (CH3SH) from a COS / H2S mixed gas.

[0026] The above-mentioned spherical alumina catalyst is used to synergistically remove COS / H2S and utilize it as a resource (catalytic synthesis of methanethiol).

[0027] Furthermore, the spherical alumina catalyst can be used alone as a catalyst for the synthesis of methanethiol from a COS / H2S mixed gas without the need to add other catalysts or load any other active ingredients.

[0028] Furthermore, the volume concentration of COS in the COS / H2S mixed gas is 10,000–800,000 ppm, and the volume concentration of H2S is 100,000–900,000 ppm; the space velocity of the COS / H2S mixed gas is 1,000–10,000 h⁻¹. -1 The synthesis reaction temperature is 200–500℃, and the reaction pressure is 0–0.2 MPa.

[0029] The present invention discloses the following technical effects:

[0030] (1) The present invention prepared a spherical alumina catalyst by hydrothermal synergistic calcination. The catalyst has a unique microsphere structure and acid-base sites, which can provide more active centers and a better reaction environment, greatly enhancing the activity and selectivity of COS / H2S to synthesize methanethiol. Thus, it has a better catalytic effect in reactions involving the synergistic removal and resource-based synthesis of methanethiol from COS / H2S.

[0031] (2) The spherical alumina of the present invention can be used alone as a catalyst for the synthesis of methanethiol from COS / H2S without the need to add other active ingredients. It has a simple composition, low cost, and good catalytic effect.

[0032] (3) The spherical alumina of this invention is expected to become a highly efficient and environmentally friendly catalyst in the synthesis of methanethiol. It can not only improve the efficiency and yield of the reaction, but also reduce the energy consumption and environmental pollution. This is of great significance for realizing green chemistry and promoting the sustainable development of the chemical industry.

[0033] (4) The preparation method of the catalyst of the present invention is simple, economical and efficient, and does not require complex equipment or harsh conditions, thus having high practical value. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 Here is a SEM image of the spherical alumina catalyst prepared in Example 1;

[0036] Figure 2 The image shows the SEM image of the alumina catalyst prepared in Comparative Example 1.

[0037] Figure 3 The graph shows the change in COS conversion rate as a function of temperature during the synthesis of CH3SH from COS / H2S catalyzed by the catalysts prepared in Examples 1-2 and Comparative Examples 1-3.

[0038] Figure 4 The graph shows the change in CH3SH selectivity as a function of temperature during the synthesis of CH3SH from COS / H2S catalyzed by the catalysts prepared in Examples 1-2 and Comparative Examples 1-3.

[0039] Figure 5 The N2 adsorption-desorption curves are shown for the catalysts prepared in Examples 1-2 and Comparative Examples 1-3.

[0040] Figure 6 The images show the pore size distribution of the catalysts prepared in Examples 1-2 and Comparative Examples 1-3. Detailed Implementation

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to 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. Every 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 in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0045] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0046] Example 1

[0047] A spherical alumina catalyst is prepared by the following steps:

[0048] 0.03 mol of alumina precursor (Al(NO3)3·6H2O), 0.03 mol of sulfate (potassium sulfate), and 0.07 mol of precipitant (urea) were dissolved in 170 mL of deionized water and stirred thoroughly for 30 min. The resulting mixed solution was transferred to a 250 mL high-pressure reactor and hydrothermally reacted at 160 °C for 4 h. After the reactor cooled to room temperature, the white precipitate in the solution was filtered and separated (the TDS value of the filtrate was <10). The solution was then washed 6 times alternately with water and ethanol. The white precipitate was collected, dried at 80 °C for 12 h, and then transferred to a muffle furnace for calcination. The temperature was increased to 550 °C at a rate of 5 °C / min and calcined for 2 h to obtain spherical alumina catalyst calcined for 2 h.

[0049] The SEM image of the spherical alumina catalyst prepared in this embodiment is shown below. Figure 1 As shown, by Figure 1 It can be seen that the spherical alumina catalyst prepared in this embodiment has a microsphere structure.

[0050] Application Example 1

[0051] The spherical alumina catalyst prepared in Example 1 and calcined for 2 hours was loaded into a tubular furnace reactor. The catalyst was pressed into tablets and sieved to a mesh size of 40–60 mesh. The loading mass was 0.4 g. A COS / H2S mixture (COS volume concentration of 10,000 ppm and H2S volume concentration of 900,000 ppm) was introduced, and the reactor was heated to carry out the catalytic reaction to synthesize CH3SH. The total space velocity of the gas feed was 3000 h⁻¹. -1 The reaction temperature range was 200–500℃, with temperature intervals of 25℃ or 50℃. The COS conversion and CH3SH selectivity were tested at temperatures of 200, 250, 300, 325, 350, 375, 400, 425, 450, 475, and 500℃, respectively. The reaction system pressure was 0.2 MPa.

[0052] The change of COS conversion rate with temperature during the reaction is as follows: Figure 3 As shown, the CH3SH selectivity changes with temperature as follows: Figure 4 As shown, from Figures 3-4 As can be seen from the data, the highest COS conversion rate reached 70.1% at 450℃, and the highest CH3SH selectivity reached 58.2% at 400℃ during the reaction process.

[0053] Example 2

[0054] Same as Example 1, except that the calcination time was 4 hours, resulting in a spherical alumina catalyst calcined for 4 hours.

[0055] Application Example 2

[0056] The spherical alumina catalyst prepared in Example 2 and calcined for 4 hours was loaded into a tubular furnace reactor. The catalyst was pressed into tablets and sieved to a mesh size of 40–60 mesh. The loading mass was 0.4 g. A COS / H2S mixture (COS volume concentration of 10,000 ppm and H2S volume concentration of 900,000 ppm) was introduced, and the reactor was heated to carry out the catalytic reaction to synthesize CH3SH. The total space velocity of the gas feed was 3000 h⁻¹. -1 The reaction temperature range is 200–500℃, with temperature intervals of 25℃ or 50℃, and the reaction system pressure is 0.2MPa.

[0057] During the reaction, the highest COS conversion rate reached 66.8% at 450℃, and the highest CH3SH selectivity reached 55.3% at 400℃.

[0058] Comparative Example 1

[0059] Same as Example 1, except that the calcination time was 6 hours to obtain an alumina catalyst.

[0060] The SEM image of the alumina catalyst prepared in this comparative example is shown below. Figure 2 As shown, by Figure 2 It can be seen that the alumina catalyst prepared in this comparative example has a sheet-like stacked structure.

[0061] Comparative Application Example 1

[0062] The alumina catalyst prepared in Comparative Example 1 and calcined for 6 hours was loaded into a tubular furnace reactor. The catalyst was pressed into tablets and sieved to a mesh size of 40–60 mesh, with a loading mass of 0.4 g. A COS / H2S mixture (COS volume concentration of 10,000 ppm and H2S volume concentration of 900,000 ppm) was introduced, and the reactor was heated to carry out the catalytic reaction to synthesize CH3SH. The total space velocity (HSV) of the gas feed was 3000 h⁻¹. -1 The reaction temperature range is 200–500℃, with temperature intervals of 25℃ or 50℃, and the reaction system pressure is 0.2MPa.

[0063] The change of COS conversion rate with temperature during the reaction is as follows: Figure 3 As shown, the CH3SH selectivity changes with temperature as follows: Figure 4 As shown, from Figures 3-4 As can be seen from the data, the highest COS conversion rate reached 59.2% at 450℃, and the highest CH3SH selectivity reached 49.7% at 425℃ during the reaction process.

[0064] Comparative Example 2

[0065] An alumina is prepared by the following steps:

[0066] 3g of P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) was dissolved in 80mL of anhydrous ethanol. After stirring on a magnetic stirrer for 2h, 6.4mL of concentrated nitric acid (68wt%) and 40mmol of aluminum isopropoxide were added to the above mixed solution in sequence. After stirring for another 8h, the final solution was placed in a forced-air drying oven and dried and aged at 80℃ for 60h. The dried pale yellow solid was placed in a muffle furnace and calcined at 550℃ at a rate of 5℃ / min for 2h to obtain the alumina catalyst calcined for 2h.

[0067] Comparative Application Example 2

[0068] The alumina catalyst prepared in Comparative Example 2 and calcined for 2 hours was loaded into a tubular furnace reactor. The catalyst was pressed into tablets and sieved to a mesh size of 40–60 mesh, with a loading mass of 0.4 g. A COS / H2S mixture (COS volume concentration of 10,000 ppm and H2S volume concentration of 900,000 ppm) was introduced, and the reactor was heated to carry out the catalytic reaction to synthesize CH3SH. The total space velocity of the gas feed was 3000 h⁻¹. -1The reaction temperature range is 200–500℃, with temperature intervals of 25℃ or 50℃, and the reaction system pressure is 0.2MPa.

[0069] The change of COS conversion rate with temperature during the reaction is as follows: Figure 3 As shown, the CH3SH selectivity changes with temperature as follows: Figure 4 As shown, from Figures 3-4 As can be seen from the data, the highest COS conversion rate reached 53.6% at 425℃, and the highest CH3SH selectivity reached 45.2% at 400℃.

[0070] Comparative Example 3

[0071] Similar to Comparative Example 2, the only difference is that the calcination time was 4 hours, resulting in an alumina catalyst calcined for 4 hours.

[0072] Comparative Application Example 3

[0073] The alumina catalyst prepared in Comparative Example 3 and calcined for 4 hours was loaded into a tubular furnace reactor. The catalyst was pressed into tablets and sieved to a mesh size of 40–60. The loading mass was 0.4 g. A COS / H2S mixed gas (COS volume concentration of 10,000 ppm and H2S volume concentration of 900,000 ppm) was introduced, and the reactor was heated to carry out the catalytic reaction to synthesize CH3SH. The total space velocity of the gas feed was 3000 h⁻¹. -1 The reaction temperature range is 200–500℃, with temperature intervals of 25℃ or 50℃, and the reaction system pressure is 0.2MPa.

[0074] The change of COS conversion rate with temperature during the reaction is as follows: Figure 3 As shown, the CH3SH selectivity changes with temperature as follows: Figure 4 As shown, from Figures 3-4 As can be seen from the data, the highest COS conversion rate reached 50.7% at 425℃, and the highest CH3SH selectivity reached 43.5% at 425℃.

[0075] The pore size distribution of the alumina catalysts prepared in Examples 1-2 and Comparative Examples 1-3 was analyzed, and N2 adsorption-desorption experiments were conducted. The experimental method was as follows: N2 adsorption-desorption was measured using a Quantachrome NOVA4200e instrument at a liquid nitrogen temperature of 77K to study the pore structure of the samples. Before analysis, 0.1 g of catalyst was degassed in a vacuum at 300℃ for 3 h to remove moisture and other contaminants. After pretreatment, the actual weight was recorded in the dialog box, and then the catalyst was loaded into the analysis station for analysis. Specific surface area and pore volume were determined using the BET method and the BJH method, respectively.

[0076] The N2 adsorption-desorption curve is shown in the figure below. Figure 5 As shown, the aperture distribution diagram is as follows: Figure 6 As shown, by Figure 5 and Figure 6 It can be seen that the catalyst prepared in Example 1 exhibits a type IV adsorption-desorption curve, indicating the presence of mesopores. The spherical alumina of Example 1 exhibits a large hysteresis loop due to the presence of numerous mesopores within the relative pressure range of P / P0 = 0.4–1.0, with the curve showing an H3-type hysteresis loop. This suggests that the mesopores in the spherical alumina calcined at 550℃ for 2 hours in Example 1 are more likely slit pores formed by the stacking of sheet-like (nanofacial) structures, with a specific surface area of ​​157 m². 2 / g, pore volume is 0.608cm³ 3 / g. The catalyst prepared in Comparative Example 1 exhibited a type IV adsorption-desorption curve, indicating the presence of mesopores. In the relative pressure range of 0.7 to 1.0, the alumina in Comparative Example 1 showed a curve more inclined towards an H1 type hysteresis loop, indicating that the mesopores in the alumina calcined at 550℃ for 6 h in Comparative Example 1 were mainly uniformly ordered cylindrical pores with a specific surface area of ​​144 m². 2 / g, pore volume is 0.397cm³ 3 / g. Compared with the spherical alumina calcined at 550℃ for 2h and 4h in Examples 1-2, it showed a significant difference, with poorer activity and selectivity. This may be due to the collapse of its spherical structure caused by excessive calcination time, resulting in a stacked lamellar structure. This indicates that calcination time has a significant impact on the morphology and performance of alumina prepared using the methods of the embodiments of the present invention. The catalyst prepared in Comparative Example 2 exhibited a type IV adsorption-desorption curve, indicating the presence of mesopores. In the relative pressure range between 0.7 and 1.0, the curve of the alumina in Comparative Example 2 tended to be a type H1 hysteresis loop, indicating that the mesopores in the alumina calcined at 550℃ for 2h in Comparative Example 2 were mainly uniformly ordered straight cylindrical pores with a specific surface area of ​​145m². 2 / g, pore volume is 0.574cm³ 3 / g. The catalyst prepared in Comparative Example 3 exhibited a type IV adsorption-desorption curve, indicating the presence of mesopores. In the relative pressure range between 0.7 and 1.0, the curve of the alumina in Comparative Example 3 tended to be a type H1 hysteresis loop, indicating that the mesopores in the alumina calcined at 550℃ for 4 h in Comparative Example 3 were mainly uniformly ordered cylindrical pores with a specific surface area of ​​141 m². 2 / g, pore volume is 0.575cm³ 3 / g. The alumina obtained by calcining at 550℃ for 2h in Comparative Example 2 was not significantly different from that obtained by calcining at 550℃ for 2h, and its activity was consistent, indicating that the calcination time had little effect on the mesoporous alumina obtained by the method of Comparative Example 2-3.

[0077] Comparative Example 4

[0078] Same as Example 1, except that the use of sulfate is omitted.

[0079] Comparative Application Example 4

[0080] The alumina catalyst prepared in Comparative Example 4 was loaded into a tubular furnace reactor. The catalyst was pressed into tablets and sieved to a mesh size of 40–60 mesh, with a loading mass of 0.4 g. A COS / H2S mixture (COS volume concentration of 10,000 ppm and H2S volume concentration of 900,000 ppm) was introduced, and the reactor was heated to carry out the catalytic reaction to synthesize CH3SH. The total space velocity of the gas feed was 3000 h⁻¹. -1 The reaction temperature range is 200–500℃, with temperature intervals of 25℃ or 50℃, and the reaction system pressure is 0.2MPa.

[0081] During the reaction, the highest COS conversion rate reached 46.3% at 450℃, and the highest CH3SH selectivity reached 35.5% at 425℃.

[0082] Comparative Example 5

[0083] Same as Example 1, except that aluminum sulfate is used instead of Al(NO3)3·6H2O in equal molar amounts, and the use of sulfate is omitted.

[0084] Comparative Application Example 5

[0085] The alumina catalyst prepared in Comparative Example 5 was loaded into a tubular furnace reactor. The catalyst was pressed into tablets and sieved to a mesh size of 40–60 mesh, with a loading mass of 0.4 g. A COS / H2S mixture (COS volume concentration of 10,000 ppm and H2S volume concentration of 900,000 ppm) was introduced, and the reactor was heated to carry out the catalytic reaction to synthesize CH3SH. The total space velocity of the gas feed was 3000 h⁻¹. -1 The reaction temperature range is 200–500℃, with temperature intervals of 25℃ or 50℃, and the reaction system pressure is 0.2MPa.

[0086] During the reaction, the highest COS conversion rate reached 49.4% at 450℃, and the highest CH3SH selectivity reached 34.6% at 425℃.

[0087] Comparative Example 6

[0088] Magnesium-based catalysts were prepared using an equal-volume impregnation method, wherein the mass fraction of active metal Mg was 8%. The specific preparation steps were as follows: 1.115 g of Mg(NO3)2·6H2O was dissolved in 3 mL of deionized water and ultrasonically vibrated for 15 min to obtain a magnesium nitrate solution. 2 g of commercial alumina (purchased from Shanghai Aladdin Reagent Co., Ltd., CAS: 1344-28-1) was poured into a crucible containing the above magnesium nitrate solution, stirred with a glass rod for 10 min, and allowed to stand for 12 h. Then, it was dried in an oven at 80 °C for 12 h, and subsequently calcined in a muffle furnace at a rate of 5 °C / min to 550 °C for 2 h to obtain the Mg / Al2O3 catalyst.

[0089] Comparative Application Example 6

[0090] The alumina catalyst prepared in Comparative Example 6 was loaded into a tubular furnace reactor. The catalyst was pressed into tablets and sieved to a mesh size of 40–60 mesh, with a loading mass of 0.4 g. A COS / H2S mixture (COS volume concentration of 10,000 ppm and H2S volume concentration of 900,000 ppm) was introduced, and the reactor was heated to carry out the catalytic reaction to synthesize CH3SH. The total space velocity of the gas feed was 3000 h⁻¹. -1 The reaction temperature range is 200–500℃, with temperature intervals of 25℃ or 50℃, and the reaction system pressure is 0.2MPa.

[0091] During this reaction, the highest COS conversion rate reached 35.3% at 450℃, and the highest CH3SH selectivity reached 30.9% at 425℃.

[0092] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. The application of a spherical alumina catalyst in the catalytic synthesis of methanethiol from a COS / H2S mixed gas, characterized in that, The preparation steps of the spherical alumina catalyst include: dissolving an alumina precursor, sulfate, and precipitant in water to obtain a mixed solution, heating to carry out a hydrothermal reaction; after the hydrothermal reaction is completed, cooling, filtering, washing, drying, and calcining to obtain the spherical alumina catalyst. The alumina precursor is aluminum nitrate; The precipitant is urea; The hydrothermal reaction is carried out at a temperature of 150–200°C for a duration of 2–6 hours. The roasting temperature is 500-600℃, and the time is 2-4 hours; The COS / H2S mixture has a volume concentration of 10,000–800,000 ppm and a H2S volume concentration of 100,000–900,000 ppm; the space velocity of the COS / H2S mixture is 1,000–10,000 h⁻¹. -1 The synthesis reaction temperature is 200–500℃, the reaction pressure is 0–0.2 MPa, and the reaction pressure is not 0.

2. The application of the spherical alumina catalyst as described in claim 1 in the catalytic synthesis of methanethiol from a COS / H2S mixed gas, characterized in that, The sulfate is potassium sulfate, sodium sulfate, or ammonium sulfate.

3. The application of the spherical alumina catalyst as described in claim 1 in the catalytic synthesis of methanethiol from a COS / H2S mixed gas, characterized in that, The ratio of alumina precursor, sulfate, precipitant and water is 0.02-0.06 mol: 0.02-0.06 mol: 0.06-0.10 mol: 150-200 mL.

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