A preparation method of a molybdenum-based catalytic material for methane-hydrogen sulfide reforming and application thereof

Abstract

The present application relates to the technical field of methane-hydrogen sulfide reforming, and particularly relates to a preparation method of a molybdenum-based catalytic material for methane-hydrogen sulfide reforming and application thereof. The preparation method comprises the following steps: S1, calcining nano-gamma alumina; S2, treating the calcined nano-gamma alumina with a sodium citrate solution; S3, treating polystyrene microspheres with dodecyl trimethyl ammonium bromide; S4, combining the nano-gamma alumina treated in step S2 with the polystyrene microspheres treated in step S3; S5, adding ammonium molybdate tetrahydrate, a metal salt and the nano-gamma alumina assembled in step S3 into deionized water to obtain a precursor; S6, calcining and grinding the precursor obtained in step S5 to obtain a primary catalytic material; and S7, sulfidizing the primary catalytic material obtained in step S6 to obtain a catalytic material. The catalytic material prepared in the present application has high activity and high conversion efficiency for methane.

Description

Technical Field

[0001] This invention relates to the field of methane-hydrogen sulfide reforming technology, specifically a method for preparing a molybdenum-based catalytic material for methane-hydrogen sulfide reforming and its application. Background Technology

[0002] With the continuous increase in energy demand, conventional oil and gas fields can no longer meet the supply, leading to the development of numerous acidic oil and gas fields. However, the acidic gases in these fields, especially hydrogen sulfide, are toxic and harmful, requiring purification. While the traditional Claus process can efficiently process hydrogen sulfide, its complex process, high energy consumption, and low-value sulfur production result in a waste of hydrogen resources. Therefore, researchers are dedicated to developing hydrogen production technologies from hydrogen sulfide to achieve its resource utilization. Among these, methane hydrogen sulfide reforming is the most mature and promising technology. It not only yields two high-value products, hydrogen and carbon disulfide, but also allows for the direct utilization of acidic natural gas, bypassing the purification process.

[0003] Molybdenum (Mo) exhibits high activity as an active component in processes such as hydrodesulfurization and hydrogen sulfide decomposition. Numerous researchers have experimentally discovered that it is also an active component in methane-hydrogen sulfide reforming, thus making it a preferred choice. However, while Mo is generally considered to activate hydrogen sulfide, the activation of methane requires the participation of other metals. Therefore, different metals were co-loaded with Mo to simultaneously promote the activation of both methane and hydrogen sulfide, thereby enhancing the overall activity.

[0004] The support plays a crucial role in the dispersion of active components, ensuring effective enhancement of catalytic activity while reducing the amount of active component required. Simultaneously, the methane-hydrogen sulfide reaction is a strongly endothermic reaction requiring high reaction temperatures; therefore, the support must be resistant to high-temperature sintering. Alumina has applications in numerous high-temperature reactions; its large specific surface area and high-temperature resistance effectively ensure the dispersion of active components. Furthermore, alumina itself is resistant to hydrogen sulfide corrosion and maintains structural stability, making it an ideal choice as a support.

[0005] Furthermore, when loading active metal ions onto alumina, the alumina used is typically nanoscale. During the loading process, the nanoscale alumina is prone to agglomeration, resulting in uneven loading of the active metal ions and a decrease in the catalytic efficiency of the catalyst. Therefore, to address the problems mentioned in the background, those skilled in the art have proposed a method for preparing a molybdenum-based catalyst for methane-hydrogen sulfide reforming. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a molybdenum-based catalytic material for methane-hydrogen sulfide reforming and its application, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing a molybdenum-based catalyst for methane-hydrogen sulfide reforming includes the following steps:

[0009] S1. Place the nano-γ-alumina in a muffle furnace and calcine it at 450-600℃ for 1-2 hours;

[0010] S2. Disperse the nano-γ-alumina treated in step S1 into a sodium citrate solution and treat for 1-2 hours. Then filter, wash the filtered product with sufficient deionized water until neutral, and dry it at 80-100℃ to constant weight.

[0011] S3. Disperse polystyrene microspheres in sulfuric acid solution, then add dodecyltrimethylammonium bromide and react continuously for 4-10 hours. After filtration, wash the filtered product with sufficient deionized water until neutral, and then dry it at 40-60℃ to constant weight.

[0012] S4. Disperse the nano-γ-alumina treated in step S2 into deionized water, add ammonia dropwise to adjust the pH to 8.5-10, then add the polystyrene microspheres treated in step S3, stir continuously for 1-3 hours, then filter, and dry the filtered product at 40-60℃ to constant weight to obtain a mixture.

[0013] S5. Add ammonium molybdate tetrahydrate and metal salt to deionized water, then add the mixture obtained in step S4, and evaporate to constant weight at 60-80℃ under stirring conditions to obtain the precursor.

[0014] S6. Place the precursor obtained in step S5 in a muffle furnace and calcine it at 450-600℃ for 4-6 hours. After natural cooling, grind it to obtain the primary catalyst material.

[0015] S7. The primary catalyst material obtained in step S6 is subjected to sulfidation treatment to obtain the catalyst material.

[0016] The metal salt in step S5 is one of the following: ferric nitrate nonahydrate, copper nitrate trihydrate, cerium nitrate hexahydrate, ruthenium chloride hydrate, cobalt nitrate hexahydrate, and nickel nitrate hexahydrate.

[0017] Furthermore, in step S2, the concentration of sodium citrate in the sodium citrate solution is 0.5-1 wt%.

[0018] Furthermore, in step S3, the concentration of sulfuric acid in the sulfuric acid solution is 0.1-0.5 mol / L, and the mass ratio between dodecyltrimethylammonium bromide, polystyrene microspheres and sulfuric acid solution is 1:(10-20):(200-400).

[0019] Furthermore, in step S4, the concentration of ammonia is 5-10 wt%, and the mass ratio between the nano-γ-alumina treated in step S2, the polystyrene microspheres treated in step S3, and deionized water is (1-2):1:(100-200).

[0020] Furthermore, the metal salt is nickel nitrate hexahydrate, and the mass ratio between ammonium molybdate tetrahydrate, nickel nitrate hexahydrate, the mixture and deionized water in step S5 is 1:(5-7):(20-30):(300-400).

[0021] Furthermore, the heating rate in step S1 is 10℃ / min, and the heating rate in step S6 is 5℃ / min.

[0022] Furthermore, the vulcanization treatment in step S7 specifically includes the following steps:

[0023] The primary catalyst material is filled into a quartz tube and placed in a fixed-bed reactor. A mixture of hydrogen sulfide and argon is introduced at a flow rate of 50-60 sccm. After heating to 500-800℃, sulfidation is carried out for 1-2 hours. Then, argon is introduced at a flow rate of 20-40 sccm and the heating is turned off for natural cooling.

[0024] Furthermore, the volume ratio of hydrogen sulfide to argon in the mixed gas of hydrogen sulfide and argon is 1:49, and the heating rate is 2℃ / min.

[0025] The application of the molybdenum-based catalyst prepared by the above-mentioned method for methane-hydrogen sulfide reforming in methane-hydrogen sulfide reforming.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. This invention improves the activity of catalytic materials and increases the conversion efficiency of methane by incorporating metal salts such as ferric nitrate nonahydrate, copper nitrate trihydrate, cerium nitrate hexahydrate, ruthenium chloride hydrate, cobalt nitrate hexahydrate, and nickel nitrate hexahydrate into alumina.

[0028] 2. This invention loads nano-gamma alumina by electrostatic means, and then the nano-gamma alumina adsorbs doped metal ions, which can effectively improve the catalytic ability of the catalytic material. This is because the polystyrene microspheres act as a carrier, preventing the nano-gamma alumina from agglomerating with each other, and the doping of metal ions is more uniform. In addition, during the calcination process, polystyrene generates gas, which is conducive to the formation of pores, increases the specific surface area of ​​the catalytic material, and improves the catalytic efficiency. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the present invention;

[0030] Figure 2 The images show the XRD patterns of the catalysts prepared in Examples 1, 4-8 and Comparative Example 4 of this invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Please see Figures 1 to 2 The present invention provides:

[0033] Example 1

[0034] A method for preparing a molybdenum-based catalyst for methane-hydrogen sulfide reforming includes the following steps:

[0035] S1. Place 4.0g of nano-γ-alumina in a muffle furnace and calcine it at 500℃ for 1.5h at a rate of 10℃ / min.

[0036] S2. The nano-γ-alumina treated in step S1 is dispersed in 100g of sodium citrate solution with a concentration of 0.6wt% and treated for 1.5h. After filtration, the filtered product is washed with sufficient deionized water until neutral and then dried at 90℃ to constant weight.

[0037] S3. Disperse 3.0g of polystyrene microspheres into 60g of 0.2mol / L sulfuric acid solution, then add 0.2g of dodecyltrimethylammonium bromide and react continuously for 6h. After filtration, wash the filtered product with sufficient deionized water until neutral, and then dry it at 50℃ to constant weight.

[0038] S4. Disperse 3.0g of nano-γ-alumina treated in step S2 into 300g of deionized water, add 8wt% ammonia water to adjust the pH to 9, then add 2.0g of polystyrene microspheres treated in step S3, stir continuously for 2h, then filter, and dry the filtered product at 50℃ to constant weight to obtain a mixture.

[0039] S5. Add 0.16g of ammonium molybdate tetrahydrate and 0.93g of nickel nitrate hexahydrate (metal salt) to 56g of deionized water, then add 4.0g of the mixture obtained in step S4, and evaporate to constant weight at 70°C under stirring to obtain the precursor.

[0040] S6. The precursor obtained in step S5 is placed in a muffle furnace and calcined at 500°C at a rate of 5°C / min for 5 hours. After natural cooling, it is ground to obtain the primary catalytic material.

[0041] S7. The primary catalyst material obtained in step S6 is subjected to sulfidation treatment to obtain the catalyst material. The specific steps of the sulfidation treatment are as follows:

[0042] The primary catalyst material was filled into a quartz tube and placed in a fixed-bed reactor. A mixture of hydrogen sulfide and argon was introduced at a flow rate of 55 sccm, with a volume ratio of 1:49. The temperature was increased to 600℃ at a rate of 2℃ / min and then sulfided for 1.2 hours. After that, argon was introduced at a flow rate of 30 sccm and the heating was turned off for natural cooling.

[0043] Example 2

[0044] A method for preparing a molybdenum-based catalyst for methane-hydrogen sulfide reforming includes the following steps:

[0045] S1. Place 4.0g of nano-γ-alumina in a muffle furnace and calcine it at 450℃ for 1h at a rate of 10℃ / min.

[0046] S2. The nano-γ-alumina treated in step S1 is dispersed in 100g of sodium citrate solution with a concentration of 0.5wt% and treated for 1h. After filtration, the filtered product is washed with sufficient deionized water until neutral and then dried at 80℃ to constant weight.

[0047] S3. Disperse 3.0g of polystyrene microspheres into 60g of 0.1mol / L sulfuric acid solution, then add 0.3g of dodecyltrimethylammonium bromide, react continuously for 5h, then filter, wash the filtered product with sufficient deionized water until neutral, and dry it at 40℃ to constant weight.

[0048] S4. Disperse 2.5g of nano-γ-alumina treated in step S2 into 250g of deionized water, add 5wt% ammonia water to adjust the pH to 8.5, then add 2.5g of polystyrene microspheres treated in step S3, stir continuously for 1h, then filter, and dry the filtered product at 40℃ to constant weight to obtain a mixture.

[0049] S5. Add 0.2g of ammonium molybdate tetrahydrate and 1.0g of nickel nitrate hexahydrate to 60g of deionized water, then add 4.0g of the mixture obtained in step S4, and evaporate to constant weight at 60°C under stirring to obtain the precursor.

[0050] S6. The precursor obtained in step S5 is placed in a muffle furnace and calcined at 450°C at a rate of 5°C / min for 4 hours. After natural cooling, it is ground to obtain the primary catalytic material.

[0051] S7. The primary catalyst material obtained in step S6 is subjected to sulfidation treatment to obtain the catalyst material. The specific steps of the sulfidation treatment are as follows:

[0052] The primary catalyst material was filled into a quartz tube and placed in a fixed-bed reactor. A mixture of hydrogen sulfide and argon was introduced at a flow rate of 50 sccm, with a volume ratio of 1:49. The temperature was increased to 500℃ at 2℃ / min and sulfided for 1 hour. Then, argon was introduced at a flow rate of 20 sccm and the heating was turned off for natural cooling.

[0053] Example 3

[0054] A method for preparing a molybdenum-based catalyst for methane-hydrogen sulfide reforming includes the following steps:

[0055] S1. Place 4.0g of nano-γ-alumina in a muffle furnace and calcine it at 600℃ for 2h at a rate of 10℃ / min.

[0056] S2. The nano-γ-alumina treated in step S1 is dispersed in 100g of sodium citrate solution with a concentration of 1wt% and treated for 2h. After filtration, the filtered product is washed with sufficient deionized water until neutral and then dried at 100℃ to constant weight.

[0057] S3. Disperse 3.0g of polystyrene microspheres into 60g of 0.5mol / L sulfuric acid solution, then add 0.15g of dodecyltrimethylammonium bromide, react continuously for 10h, then filter, wash the filtered product with sufficient deionized water until neutral, and dry it at 60℃ to constant weight;

[0058] S4. Disperse 3.0g of nano-γ-alumina treated in step S2 into 300g of deionized water, add 10wt% ammonia water to adjust the pH to 10, then add 1.5g of polystyrene microspheres treated in step S3, stir continuously for 3h, then filter, and dry the filtered product at 60℃ to constant weight to obtain a mixture.

[0059] S5. Add 0.13 g of ammonium molybdate tetrahydrate and 0.91 g of nickel nitrate hexahydrate to 52 g of deionized water, then add 4.0 g of the mixture obtained in step S4, and evaporate to constant weight at 80 °C under stirring to obtain the precursor.

[0060] S6. The precursor obtained in step S5 is placed in a muffle furnace and calcined at 600°C at a rate of 5°C / min for 6 hours. After natural cooling, it is ground to obtain the primary catalytic material.

[0061] S7. The primary catalyst material obtained in step S6 is subjected to sulfidation treatment to obtain the catalyst material. The specific steps of the sulfidation treatment are as follows:

[0062] The primary catalyst material was filled into a quartz tube and placed in a fixed-bed reactor. A mixture of hydrogen sulfide and argon was introduced at a flow rate of 60 sccm, with a volume ratio of 1:49. The temperature was increased to 800℃ at a rate of 2℃ / min and then sulfided for 2 hours. After that, argon was introduced at a flow rate of 40 sccm and the heating was turned off for natural cooling.

[0063] The metal salt in step S5 can also be one of ferric nitrate nonahydrate, copper nitrate trihydrate, cerium nitrate hexahydrate, ruthenium chloride hydrate, and cobalt nitrate hexahydrate.

[0064] Example 4

[0065] The difference between Example 4 and Example 1 is that nickel nitrate hexahydrate in step S5 is replaced with 0.93g of cobalt nitrate hexahydrate, while the rest of the steps are exactly the same as in Example 1.

[0066] Example 5

[0067] The difference between Example 5 and Example 1 is that nickel nitrate hexahydrate in step S5 is replaced with 0.73g of copper nitrate trihydrate, while the rest of the steps are exactly the same as in Example 1.

[0068] Example 6

[0069] The difference between Example 6 and Example 1 is that nickel nitrate hexahydrate in step S5 is replaced with 0.61g of cerium nitrate hexahydrate, while the rest of the steps are exactly the same as in Example 1.

[0070] Example 7

[0071] The difference between Example 7 and Example 1 is that nickel nitrate hexahydrate in step S5 is replaced with 1.21g of ferric nitrate nonahydrate, while the rest of the steps are exactly the same as in Example 1. Comparative Example 1

[0072] Example 8

[0073] The difference between Example 5 and Example 1 is that nickel nitrate hexahydrate in step S5 is replaced with 0.49g of ruthenium chloride hydrate, while the rest of the steps are exactly the same as in Example 1.

[0074] Comparative Example 1

[0075] The difference between Comparative Example 1 and Example 1 is that step S2 was completely omitted, and nano-γ-alumina that had not been treated in step S2 was added in step S4. The remaining steps were exactly the same as in Example 1.

[0076] Comparative Example 2

[0077] The difference between Comparative Example 2 and Example 1 is that step S3 was completely omitted, and polystyrene microspheres that had not been treated in step S3 were added in step S4. The remaining steps were exactly the same as in Example 1.

[0078] Comparative Example 3

[0079] The difference between Comparative Example 3 and Example 1 is that steps S2-S4 were omitted, and nano-gamma alumina treated in step S1 was directly added in step S5. The amount of nano-gamma alumina used was 2.4g. The remaining steps were exactly the same as in Example 1.

[0080] Comparative Example 4

[0081] The difference between Comparative Example 4 and Example 1 is that the addition of nickel nitrate hexahydrate in step S5 was completely eliminated, while the remaining steps are exactly the same as in Example 1.

[0082] The polystyrene microspheres used in the above embodiments have a particle size of 50-100 μm, and the nano-γ-alumina has a particle size of 10-50 nm.

[0083] The catalytic materials prepared in Examples 1-8 and Comparative Examples 1-4 were subjected to activity testing. The specific test conditions were as follows: methane:hydrogen sulfide ratio of 1:2, total gas flow rate of 100 sccm, reaction pressure of 0.1 MPa, catalytic material dosage of 0.05 g, and reaction temperature of 800 °C. The specific test steps were as follows: First, the catalytic material was filled into a quartz tube and installed on a fixed-bed reactor. Methane and hydrogen sulfide were introduced in proportion. After the gas flow rate stabilized, the fixed-bed reactor was set to heat to 800 °C at a rate of 5 °C / min and maintained at this temperature. The gas chromatograph was set to automatically inject the sample, and data were collected every 30 min. The test results are shown in Table 1 below.

[0084] Table 1: Methane conversion rate of the catalysts prepared in Examples 1-8 and Comparative Examples 1-4

[0085]

[0086] A comparison of Examples 1-8 and Comparative Example 4 shows that incorporating metal salts such as ferric nitrate nonahydrate, copper nitrate trihydrate, cerium nitrate hexahydrate, ruthenium chloride hydrate, cobalt nitrate hexahydrate, and nickel nitrate hexahydrate in step S5 can effectively improve the conversion efficiency of methane. A comparison of Example 1 and Comparative Examples 1-3 shows that in this invention, using polystyrene microspheres as a template, electrostatically loading nano-gamma alumina, and then allowing the nano-gamma alumina to adsorb doped metal ions, can effectively improve the catalytic ability of the catalytic material. This is because the polystyrene microspheres act as a carrier, preventing the nano-gamma alumina from agglomerating, resulting in more uniform metal ion doping. Figure 2 The XRD pattern shows that no obvious peaks of molybdenum oxide and other metal oxides appeared after loading Mo and other metals, indicating that the metals are highly dispersed on the surface of alumina. In addition, during the calcination process, polystyrene generates gas, which can facilitate the formation of pores, increase the specific surface area of ​​the catalytic material, and improve the catalytic efficiency.

[0087] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a molybdenum-based catalytic material for methane-hydrogen sulfide reforming, characterized in that, Includes the following steps: S1. Place the nano-γ-alumina in a muffle furnace and calcine it at 450-600℃ for 1-2 hours; S2. Disperse the nano-γ-alumina treated in step S1 into a sodium citrate solution and treat for 1-2 hours. Then filter, wash the filtered product with sufficient deionized water until neutral, and dry it at 80-100℃ to constant weight. S3. Disperse polystyrene microspheres in sulfuric acid solution, then add dodecyltrimethylammonium bromide and react continuously for 4-10 hours. After filtration, wash the filtered product with sufficient deionized water until neutral, and then dry it at 40-60℃ to constant weight. S4. Disperse the nano-γ-alumina treated in step S2 into deionized water, add ammonia dropwise to adjust the pH to 8.5-10, then add the polystyrene microspheres treated in step S3, stir continuously for 1-3 hours, then filter, and dry the filtered product at 40-60℃ to constant weight to obtain a mixture. S5. Add ammonium molybdate tetrahydrate and metal salt to deionized water, then add the mixture obtained in step S4, and evaporate to constant weight at 60-80℃ under stirring conditions to obtain the precursor. S6. Place the precursor obtained in step S5 in a muffle furnace and calcine it at 450-600℃ for 4-6 hours. After natural cooling, grind it to obtain the primary catalyst material. S7. The primary catalyst material obtained in step S6 is subjected to sulfidation treatment to obtain the catalyst material. The metal salt in step S5 is one of the following: ferric nitrate nonahydrate, copper nitrate trihydrate, cerium nitrate hexahydrate, ruthenium chloride hydrate, cobalt nitrate hexahydrate, and nickel nitrate hexahydrate; In step S2, the concentration of sodium citrate in the sodium citrate solution is 0.5-1 wt%. In step S3, the concentration of sulfuric acid in the sulfuric acid solution is 0.1-0.5 mol / L, and the mass ratio between dodecyltrimethylammonium bromide, polystyrene microspheres and sulfuric acid solution is 1:(10-20):(200-400).

2. The method for preparing the molybdenum-based catalytic material for methane-hydrogen sulfide reforming according to claim 1, characterized in that, In step S4, the concentration of ammonia is 5-10 wt%, and the mass ratio of nano-γ-alumina treated in step S2, polystyrene microspheres treated in step S3, and deionized water is (1-2):1:(100-200).

3. The method for preparing the molybdenum-based catalyst for methane-hydrogen sulfide reforming according to claim 1, characterized in that, The metal salt is nickel nitrate hexahydrate, and the mass ratio of ammonium molybdate tetrahydrate, nickel nitrate hexahydrate, the mixture and deionized water in step S5 is 1:(5-7):(20-30):(300-400).

4. The method for preparing the molybdenum-based catalyst for methane-hydrogen sulfide reforming according to claim 1, characterized in that, The heating rate in step S1 is 10℃ / min, and the heating rate in step S6 is 5℃ / min.

5. The method for preparing the molybdenum-based catalyst for methane-hydrogen sulfide reforming according to claim 1, characterized in that, The vulcanization treatment in step S7 specifically includes the following steps: The primary catalyst material is filled into a quartz tube and placed in a fixed-bed reactor. A mixture of hydrogen sulfide and argon is introduced at a flow rate of 50-60 sccm. After heating to 500-800℃, sulfidation is carried out for 1-2 hours. Then, argon is introduced at a flow rate of 20-40 sccm and the heating is turned off for natural cooling.

6. The method for preparing the molybdenum-based catalyst for methane-hydrogen sulfide reforming according to claim 5, characterized in that, The volume ratio of hydrogen sulfide to argon in the mixed gas is 1:49, and the heating rate is 2℃ / min.

7. The application of the catalytic material prepared by the method for preparing molybdenum-based catalytic material for methane-hydrogen sulfide reforming as described in any one of claims 1-6 in methane-hydrogen sulfide reforming.

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