A water and sulfur resistant primary and secondary hydrogen conversion catalyst and a method for making the same

Abstract

The application discloses a kind of water-resistant and sulfur-resistant primary and secondary hydrogen conversion catalyst and its preparation method, the primary and secondary hydrogen conversion catalyst is MnO2-CaO-WO3-TiO2, it includes MnO2 as active agent, CaO as sacrificial agent, WO3 as structure auxiliary agent and TiO2 as sulfur-resistant oxide four components, four components according to mass percentage, the content of MnO2 is 50~80% of the total mass of primary and secondary hydrogen conversion catalyst, the content of CaO is 5~10% of the total mass of primary and secondary hydrogen conversion catalyst, the content of WO3 is 1~5% of the total mass of primary and secondary hydrogen conversion catalyst, the content of TiO2 is 5~44% of the total mass of primary and secondary hydrogen conversion catalyst;Advantages are that the primary and secondary hydrogen conversion catalyst does not contain iron, and is water-resistant, sulfur-resistant, and will not appear the phenomenon of rapid deactivation.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and in particular relates to a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst and its preparation method. Background Technology

[0002] Green hydrogen, characterized by zero carbon emissions, is rapidly developing in China. Green hydrogen (referred to as green hydrogen) can be used as a power fuel in fuel cells, as a reducing agent to replace CO in the steel and metallurgical industries, and is also an important hydrogenation feedstock in the chemical and food industries. It has very wide applications in global industry. Currently, hydrogen produced by electrolyzing water using electricity generated from renewable energy sources such as wind and solar power is called green hydrogen. The large-scale storage and transportation of green hydrogen urgently needs to be addressed.

[0003] Liquefying hydrogen at low temperatures of 20–77 K to obtain liquid hydrogen (referred to as liquid hydrogen) can significantly increase the volumetric energy density of hydrogen storage and transportation (70 times that of high-pressure gaseous hydrogen), and can greatly reduce the cost of long-distance hydrogen transportation, thus enabling large-scale transoceanic storage and transportation of green hydrogen. Therefore, hydrogen liquefaction is a very promising green hydrogen storage and transportation technology.

[0004] A hydrogen molecule has two H atoms, namely two protons and two electrons, and has two configurations: 1) when the two protons have the same spin, it is called orthohydrogen; 2) when the two protons have opposite spins, it is called secondary hydrogen. At room temperature, hydrogen gas is composed of 75% orthohydrogen and 25% secondary hydrogen. As the storage temperature decreases, orthohydrogen spontaneously converts to secondary hydrogen, but the conversion rate is very slow. The conversion process releases a large amount of heat, which can cause the liquid hydrogen in the vacuum liquid hydrogen storage tank to completely vaporize, resulting in significant losses. Therefore, during hydrogen liquefaction, a catalyst is needed to rapidly convert orthohydrogen into the more stable secondary hydrogen, ensuring that the secondary hydrogen content in the liquid hydrogen leaving the plant exceeds 95%. This reaction is called orthohydrogen-secondary hydrogen conversion, and the catalyst is called an orthohydrogen-secondary hydrogen conversion catalyst.

[0005] Currently, commercially available n- and bis-hydrogen conversion catalysts are produced by Molecular Corporation in the United States. The catalyst is Fe₂O₃. The reaction was carried out at 1.36 bar, 77 K, and a gas hourly space velocity (GHSV) of 1200 ml / min. -1 ·ml cat -1Under reaction conditions where the inlet gas composition is 75% positive hydrogen and 25% negative hydrogen, a negative hydrogen concentration of no less than 46.5% can be achieved at the outlet. However, this catalyst is not resistant to sulfur; trace amounts of SO2 and H2S in the feed gas will cause rapid and irreversible deactivation of the catalyst. The catalyst is also not water-resistant. Although an adsorption drying device is installed before the positive and negative hydrogen reactor for feed dehydration, due to the adsorption equilibrium, trace amounts of water will still enter the positive and negative hydrogen reactor, contact the catalyst, and cause rapid deactivation of the Fe2O3 catalyst. In severe cases, ice formation and blockage of the positive and negative hydrogen reactor can occur.

[0006] Meanwhile, domestic efforts have also been undertaken to develop secondary hydrogen catalysts. Patent document CN116966914A discloses a secondary hydrogen catalyst with a metal single atom supported on iron oxide, where the iron oxide content is as high as 95-99.9%. Patent document CN116532117A prepares a Fe / Co bimetallic oxide catalyst using ammonia precipitation, with a Fe:Co ratio of 10:(1-5). Patent document CN116532116A prepares a Fe / Al2O3 catalyst via precipitation, with Fe:Al2O3 = (8-12):1. Patent document CN115920919A prepares a Fe / α-MnO2 catalyst, with an α-MnO2:Fe ratio of 100:5-20. Patent document CN114367288B prepares a pure Fe-based catalyst with low alkali metal content using a weak precipitant. Patent document CN112844443A requires a mesoporous ordered material as a catalyst support. As can be seen from the reported patent literature, all of them use Fe as the main active component, and imported commercial catalysts. There is no essential difference, and no attempt has been made to solve the problem of catalysts being susceptible to sulfur and water in the conversion of positive and negative hydrogen, which leads to the need for complicated pretreatment processes in the liquid hydrogen process.

[0007] Therefore, there is an urgent need to develop an iron-free, water-resistant, and sulfur-resistant catalyst for the conversion of n- and tertiary hydrogen. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst and its preparation method. The secondary hydrogen conversion catalyst is iron-free, water-resistant, sulfur-resistant, and will not exhibit rapid deactivation.

[0009] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst, characterized in that the secondary hydrogen conversion catalyst is MnO2-CaO-WO3-TiO2, the secondary hydrogen conversion catalyst comprises four components: MnO2 as an activator, CaO as a sacrificial agent, WO3 as a structural aid, and TiO2 as an anti-sulfur oxide. The content of MnO2, CaO, WO3, and TiO2 is 50-80% of the total mass of the secondary hydrogen conversion catalyst, 5-10% of the total mass of the secondary hydrogen conversion catalyst, 1-5% of the total mass of the secondary hydrogen conversion catalyst, and 5-44% of the total mass of the secondary hydrogen conversion catalyst, by mass percentage.

[0010] In a preferred embodiment, the content of MnO2 is 60-70% of the total mass of the n- and secondary hydroconversion catalyst, the content of CaO is 6-8% of the total mass of the n- and secondary hydroconversion catalyst, the content of WO3 is 2-3% of the total mass of the n- and secondary hydroconversion catalyst, and the content of TiO2 is 19-32% of the total mass of the n- and secondary hydroconversion catalyst.

[0011] A method for preparing the above-mentioned water-resistant and sulfur-resistant secondary hydrogen conversion catalyst is characterized by comprising the following steps:

[0012] Step S1: Dissolve the required amounts of soluble precursor salts of Mn and W together in a mixed solution of deionized water and ethanol to form solution A;

[0013] Step S2: Add dispersant to solution A and stir until the dispersant is completely dissolved to form solution B; here, the addition of dispersant can effectively inhibit the rapid growth of crystals during nucleation and avoid particle aggregation.

[0014] Step S3: Dissolve the required amount of the soluble precursor salt of Ti in ethanol to form solution C;

[0015] Step S4: Slowly add solution C dropwise to solution B while vigorously stirring solution B during the addition process; after the addition is complete, continue stirring for a period of time to form suspension D;

[0016] Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand and react for a period of time at a certain temperature; then let it cool naturally to room temperature to obtain the mixture E;

[0017] Step S6: Discard the supernatant of mixture E and remove the lower precipitate; then wash the removed lower precipitate alternately with deionized water and ethanol to obtain precipitate F;

[0018] Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at a certain temperature; then calcine it at a certain temperature for a period of time; and then cool it naturally to room temperature to obtain powder G;

[0019] Step S8: Dissolve the required amount of soluble precursor salt of Ca in deionized water to obtain solution H; then add powder G to solution H, heat to a certain temperature, and evaporate the water in solution H under stirring to obtain powder I impregnated with Ca.

[0020] Step S9: Transfer powder I to an oven and let it stand and dry overnight at a certain temperature; then calcine it at a certain temperature for a period of time; and then cool it naturally to room temperature to obtain the target material, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2.

[0021] In step S1, the soluble precursor salt of Mn is selected from at least one of manganese nitrate and manganese chloride. In practice, usually only one is selected, and it is rare to select multiple types for mixing. The soluble precursor salt of W is selected from at least one of ammonium metatungstate, ammonium tungstate, and sodium tungstate. In practice, usually only one is selected, and it is rare to select multiple types for mixing. The volume ratio of deionized water to ethanol in the mixed solution is (15-3):1, preferably (10-5):1. The total ion concentration of Mn and W in solution A is 0.2-3 mol / L, preferably 1-2 mol / L.

[0022] In step S2, the dispersant is PEG4000 (Polyethylene Glycol 4000), and the molar amount of the dispersant is 0.2-3% of the total molar amount of Mn and W ions, preferably 0.5-1%.

[0023] In step S3, the soluble precursor salt of Ti is selected from at least one of tetrabutyl titanate, tetraethyl titanate, and isopropyl titanate. In actual implementation, one of them is usually selected, and it is rare to select multiple ones for mixing. The mass ratio of solvent (ethanol) to solute (soluble precursor salt of Ti) in solution C is (5-30):1, preferably (10-20):1.

[0024] In step S4, after the addition is completed, stirring continues for 0.5 to 3 hours, preferably 1 to 2 hours; in step S5, the reaction temperature in the oven is 120 to 200°C, preferably 150 to 180°C, and the reaction time is 12 to 36 hours, preferably 16 to 24 hours; in steps S7 and S9, the drying temperature in the oven is 100 to 150°C, preferably 110 to 120°C; the calcination temperature is 400 to 700°C, preferably 500 to 600°C, and the calcination time is 3 to 8 hours.

[0025] In step S6, the amount of deionized water used is 250 ml, the amount of ethanol used is 250 ml, and the number of times the washing is alternated is 5.

[0026] In step S8, the soluble precursor salt of Ca is selected from at least one of calcium nitrate, calcium chloride, calcium acetate, and calcium propionate. In practice, usually only one is selected, and it is rare to select multiple types for mixing; Ca in solution H 2+ The ion concentration is 0.05–0.2 mol / L; powder G is added to solution H, and the water in solution H is evaporated to dryness while stirring after the temperature is raised to 90°C.

[0027] Compared with the prior art, the advantages of the present invention are as follows:

[0028] 1) This invention uses MnO2 as a component of the ortho- and para-hydrogen conversion catalyst. This is because the outer valence electron structure of Mn in MnO2 is 4S. 2 3D 5 The atomic magnetic moment is 5μ B It is very similar to Fe (Fe has an outer valence electron structure of 4S). 2 3D 6 In actual tests, MnO2 also exhibited high activity for the conversion of n- and secondary hydrogen, therefore MnO2 was used as an activator. This invention uses CaO as a component of the n- and secondary hydrogen conversion catalyst. Since CaO is an alkaline earth metal oxide with strong water absorption properties, it is used as a sacrificial agent, allowing trace amounts of water in the reaction gas to preferentially adsorb onto the surface of CaO, thereby protecting the n- and secondary hydrogen conversion activity of MnO2. This invention uses WO3 as a component of the n- and secondary hydrogen conversion catalyst. WO3 is an excellent structural additive; its appropriate addition to the catalyst can enhance its hardness and structural stability. This invention uses TiO2 as a component of the n- and secondary hydrogen conversion catalyst. TiO2 is an excellent sulfur-resistant oxide.

[0029] 2) The proposed secondary hydrogen conversion catalyst does not contain Fe, which breaks through the traditional Fe-based catalyst.

[0030] 3) By adding Ca, W and Ti to Mn, this invention effectively achieves the water resistance and sulfur resistance of the catalyst through synergistic effects, greatly expands the range of sources of raw hydrogen, simplifies the pretreatment of raw gas, extends the service life of the catalyst, and accelerates the development of hydrogen liquefaction technology.

[0031] 4) The four-component MnO2-CaO-WO3-TiO2 positive and negative hydrogen conversion catalyst prepared by the method of the present invention has high activity and strong resistance to water and sulfur. When the SO2 content in the feed gas is in the range of 1 to 200 ppm and H2O is in the range of 1 to 500 ppm, the conversion rate can reach more than 95% at 77 K and the secondary hydrogen equilibrium concentration exceeds 48%.

[0032] 5) The preparation process of the method of the present invention is simple, the raw materials are widely available, the cost is low, and the solvents used in the preparation process are only water and ethanol, which are non-corrosive strong alkaline solvents. The whole preparation process is environmentally friendly and economical. Attached Figure Description

[0033] Figure 1 SEM image of the MnO2-CaO-WO3-TiO2 four-component n-parahydrogen conversion catalyst prepared by the preparation method of Example 1. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] Example 1:

[0036] This embodiment presents an iron-free, water-resistant, and sulfur-resistant secondary hydrogen conversion catalyst, which is MnO2-CaO-WO3-TiO2. It comprises four components: MnO2 as an activator, CaO as a sacrificial agent, WO3 as a structural aid, and TiO2 as an anti-sulfur oxide. The four components are present in the following mass percentages: MnO2 accounts for 60% of the total mass of the secondary hydrogen conversion catalyst, CaO accounts for 6% of the total mass of the secondary hydrogen conversion catalyst, WO3 accounts for 2% of the total mass of the secondary hydrogen conversion catalyst, and TiO2 accounts for 32% of the total mass of the secondary hydrogen conversion catalyst.

[0037] The preparation method of the above-mentioned MnO2-CaO-WO3-TiO2 hydrogen conversion catalyst includes the following steps:

[0038] Step S1: Weigh 39.6g of manganese nitrate hexahydrate as the soluble precursor salt of Mn, and weigh 0.4g of ammonium metatungstate as the soluble precursor salt of W; then dissolve the soluble precursor salts of Mn and W together in a mixed solution of 127mL of deionized water and 12.7mL of ethanol, and stir until completely dissolved to form solution A. The total ion concentration of Mn and W in solution A is 1mol / L.

[0039] Step S2: Weigh 5.6g of commercially available polyethylene glycol PEG4000 as a dispersant; then add the dispersant to solution A and stir until the dispersant is completely dissolved to form solution B. Here, the addition of the dispersant can effectively inhibit the rapid growth of crystals during nucleation and avoid particle aggregation; the molar amount of PEG4000 is 1% of the total molar amount of Mn and W ions.

[0040] Step S3: Weigh 27.2g of tetrabutyl titanate as the soluble precursor salt of Ti; then dissolve the soluble precursor salt of Ti in 272g of ethanol and stir until completely dissolved to form solution C. The mass ratio of solvent (ethanol) to solute (soluble precursor salt of Ti) in solution C is 10:1.

[0041] Step S4: Slowly add solution C dropwise to solution B while stirring solution B vigorously during the addition process; after the addition is complete, continue stirring for 1 hour to form suspension D.

[0042] Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand at 150°C for 24 hours; then let it cool naturally to room temperature to obtain a layered mixture E.

[0043] Step S6: Discard the supernatant of mixture E, separate and remove the lower precipitate; then wash the removed lower precipitate alternately with 250ml of deionized water and 250ml of ethanol, for a total of 5 washes, to obtain precipitate F.

[0044] Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at 120°C; then take it out and place it in a muffle furnace and calcine it at 500°C for 4 hours; then let it cool naturally to room temperature to obtain powder G.

[0045] Step S8: Weigh 5.1 g of calcium nitrate tetrahydrate as the soluble precursor salt of Ca; then dissolve the soluble precursor salt of Ca in 214 mL of deionized water to obtain solution H. The Ca in solution H... 2+ The ion concentration was 0.1 mol / L; then powder G was added to solution H, and the temperature was raised to 90℃. The water in solution H was evaporated while stirring to obtain powder I impregnated with Ca.

[0046] Step S9: Transfer powder I to an oven and let it stand and dry overnight at 120°C; then take it out and place it in a muffle furnace and calcine it at 500°C for 4 hours; then cool it naturally to room temperature to obtain the target product, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2. According to the mass percentage, the content of MnO2 is 60% of the total mass of the secondary hydrogen conversion catalyst, the content of CaO is 6% of the total mass of the secondary hydrogen conversion catalyst, the content of WO3 is 2% of the total mass of the secondary hydrogen conversion catalyst, and the content of TiO2 is 32% of the total mass of the secondary hydrogen conversion catalyst.

[0047] Figure 1 SEM images of the MnO2-CaO-WO3-TiO2 four-component n-parahydrogen conversion catalyst prepared by the preparation method in Example 1 are provided.

[0048] Example 2:

[0049] This embodiment presents an iron-free, water-resistant, and sulfur-resistant secondary hydroconversion catalyst, which is MnO2-CaO-WO3-TiO2. It comprises four components: MnO2 as an activator, CaO as a sacrificial agent, WO3 as a structural aid, and TiO2 as an anti-sulfur oxide. The four components are present in the following mass percentages: MnO2 accounts for 50% of the total mass of the secondary hydroconversion catalyst, CaO accounts for 5% of the total mass of the secondary hydroconversion catalyst, WO3 accounts for 5% of the total mass of the secondary hydroconversion catalyst, and TiO2 accounts for 40% of the total mass of the secondary hydroconversion catalyst.

[0050] The preparation method of the above-mentioned MnO2-CaO-WO3-TiO2 hydrogen conversion catalyst includes the following steps:

[0051] Step S1: Weigh 34.1g of manganese chloride tetrahydrate as the soluble precursor salt of Mn, and weigh 1.6g of ammonium metatungstate as the soluble precursor salt of W; then dissolve the soluble precursor salts of Mn and W together in a mixed solution of 298mL of deionized water and 60mL of ethanol, and stir until completely dissolved to form solution A. The total ion concentration of Mn and W in solution A is 0.5mol / L.

[0052] Step S2: Weigh 3.6g of commercially available polyethylene glycol PEG4000 as a dispersant; then add the dispersant to solution A and stir until the dispersant is completely dissolved to form solution B. Here, the addition of the dispersant can effectively inhibit the rapid growth of crystals during nucleation and avoid particle aggregation; the molar amount of PEG4000 is 0.5% of the total molar amount of Mn and W ions.

[0053] Step S3: Weigh 42.7g of isopropyl titanate as the soluble precursor salt of Ti; then dissolve the soluble precursor salt of Ti in 854g of ethanol and stir until completely dissolved to form solution C. The mass ratio of solvent (ethanol) to solute (soluble precursor salt of Ti) in solution C is 20:1.

[0054] Step S4: Slowly add solution C dropwise to solution B while stirring solution B vigorously during the addition process; after the addition is complete, continue stirring for 0.5 hours to form suspension D.

[0055] Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand at 150°C for 24 hours; then let it cool naturally to room temperature to obtain a layered mixture E.

[0056] Step S6: Discard the supernatant of mixture E, separate and remove the lower precipitate; then wash the removed lower precipitate alternately with 250ml of deionized water and 250ml of ethanol, for a total of 5 washes, to obtain precipitate F.

[0057] Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at 110°C; then take it out and place it in a muffle furnace and calcine it at 600°C for 4 hours; then cool it naturally to room temperature to obtain powder G.

[0058] Step S8: Weigh 4.7g of calcium acetate as the soluble precursor salt of Ca; then dissolve the soluble precursor salt of Ca in 535mL of deionized water to obtain solution H. The Ca in solution H... 2+ The ion concentration was 0.05 mol / L; then powder G was added to solution H, heated to 90℃, and the water in solution H was evaporated while stirring to obtain powder I impregnated with Ca.

[0059] Step S9: Transfer powder I to an oven and let it stand and dry overnight at 110°C; then take it out and place it in a muffle furnace and calcine it at 600°C for 4 hours; then cool it naturally to room temperature to obtain the target product, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2. According to the mass percentage, the content of MnO2 is 50% of the total mass of the secondary hydrogen conversion catalyst, the content of CaO is 5% of the total mass of the secondary hydrogen conversion catalyst, the content of WO3 is 5% of the total mass of the secondary hydrogen conversion catalyst, and the content of TiO2 is 40% of the total mass of the secondary hydrogen conversion catalyst.

[0060] Example 3:

[0061] This embodiment presents an iron-free, water-resistant, and sulfur-resistant secondary hydroconversion catalyst, which is MnO2-CaO-WO3-TiO2. It comprises four components: MnO2 as an activator, CaO as a sacrificial agent, WO3 as a structural aid, and TiO2 as an anti-sulfur oxide. The four components are, by mass percentage, 80% of the total mass of the secondary hydroconversion catalyst, 6% of the total mass of the secondary hydroconversion catalyst of MnO2, 1% of the total mass of the secondary hydroconversion catalyst of CaO, 13% of the total mass of the secondary hydroconversion catalyst of WO3, and 13% of the total mass of the secondary hydroconversion catalyst of TiO2.

[0062] The preparation method of the above-mentioned MnO2-CaO-WO3-TiO2 hydrogen conversion catalyst includes the following steps:

[0063] Step S1: Weigh 54.6g of manganese chloride tetrahydrate as the soluble precursor salt of Mn, and weigh 0.3g of ammonium metatungstate as the soluble precursor salt of W; then dissolve the soluble precursor salts of Mn and W together in a mixed solution of 130mL of deionized water and 8.7mL of ethanol, and stir until completely dissolved to form solution A. The total ion concentration of Mn and W in solution A is 2mol / L.

[0064] Step S2: Weigh 2.2g of commercially available polyethylene glycol PEG4000 as a dispersant; then add the dispersant to solution A and stir until the dispersant is completely dissolved to form solution B. Here, the addition of the dispersant effectively inhibits rapid crystal growth during nucleation and prevents particle aggregation; the molar amount of PEG4000 is 0.2% of the total molar amount of Mn and W ions.

[0065] Step S3: Weigh 16.6g of tetrabutyl titanate as the soluble precursor salt of Ti; then dissolve the soluble precursor salt of Ti in 498g of ethanol and stir until completely dissolved to form solution C. The mass ratio of solvent (ethanol) to solute (soluble precursor salt of Ti) in solution C is 30:1.

[0066] Step S4: Slowly add solution C dropwise to solution B while stirring solution B vigorously during the addition process; after the addition is complete, continue stirring for 3 hours to form suspension D.

[0067] Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand at 180°C for 16 hours; then let it cool naturally to room temperature to obtain a layered mixture E.

[0068] Step S6: Discard the supernatant of mixture E, separate and remove the lower precipitate; then wash the removed lower precipitate alternately with 250ml of deionized water and 250ml of ethanol, for a total of 5 washes, to obtain precipitate F.

[0069] Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at 130°C; then take it out and place it in a muffle furnace and calcine it at 400°C for 8 hours; then cool it naturally to room temperature to obtain powder G.

[0070] Step S8: Weigh 3.6g of calcium chloride as the soluble precursor salt of Ca; then dissolve the soluble precursor salt of Ca in 160mL of deionized water to obtain solution H. The Ca in solution H... 2+ The ion concentration was 0.2 mol / L; then powder G was added to solution H, and the temperature was raised to 90℃. The water in solution H was evaporated while stirring to obtain powder I impregnated with Ca.

[0071] Step S9: Transfer powder I to an oven and let it stand and dry overnight at 130°C; then take it out and place it in a muffle furnace and calcine it at 400°C for 8 hours; then cool it naturally to room temperature to obtain the target product, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2. According to the mass percentage, the content of MnO2 is 80% of the total mass of the secondary hydrogen conversion catalyst, the content of CaO is 6% of the total mass of the secondary hydrogen conversion catalyst, the content of WO3 is 1% of the total mass of the secondary hydrogen conversion catalyst, and the content of TiO2 is 13% of the total mass of the secondary hydrogen conversion catalyst.

[0072] Example 4:

[0073] This embodiment presents an iron-free, water-resistant, and sulfur-resistant secondary hydroconversion catalyst, which is MnO2-CaO-WO3-TiO2. It comprises four components: MnO2 as an activator, CaO as a sacrificial agent, WO3 as a structural aid, and TiO2 as an anti-sulfur oxide. The four components are present in the following mass percentages: MnO2 accounts for 70% of the total mass of the secondary hydroconversion catalyst, CaO accounts for 10% of the total mass of the secondary hydroconversion catalyst, WO3 accounts for 1% of the total mass of the secondary hydroconversion catalyst, and TiO2 accounts for 19% of the total mass of the secondary hydroconversion catalyst.

[0074] The preparation method of the above-mentioned MnO2-CaO-WO3-TiO2 hydrogen conversion catalyst includes the following steps:

[0075] Step S1: Weigh 69.3g of manganese nitrate hexahydrate as the soluble precursor salt of Mn, and weigh 0.3g of ammonium tungstate as the soluble precursor salt of W; then dissolve the soluble precursor salts of Mn and W together in a mixed solution of 364mL of deionized water and 121mL of ethanol, and stir until completely dissolved to form solution A. The total ion concentration of Mn and W in solution A is 0.5mol / L.

[0076] Step S2: Weigh 29.3g of commercially available polyethylene glycol PEG4000 as a dispersant; then add the dispersant to solution A and stir until the dispersant is completely dissolved to form solution B. Here, the addition of the dispersant can effectively inhibit the rapid growth of crystals during nucleation and avoid particle aggregation; the molar amount of PEG4000 is 3% of the total molar amount of Mn and W ions.

[0077] Step S3: Weigh 16.3g of tetraethyl titanate as the soluble precursor salt of Ti; then dissolve the soluble precursor salt of Ti in 244g of ethanol and stir until completely dissolved to form solution C. The mass ratio of solvent (ethanol) to solute (soluble precursor salt of Ti) in solution C is approximately 15:1.

[0078] Step S4: Slowly add solution C dropwise to solution B while stirring solution B vigorously during the addition process; after the addition is complete, continue stirring for 2 hours to form suspension D.

[0079] Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand at 200°C for 12 hours; then let it cool naturally to room temperature to obtain a layered mixture E.

[0080] Step S6: Discard the supernatant of mixture E, separate and remove the lower precipitate; then wash the removed lower precipitate alternately with 250ml of deionized water and 250ml of ethanol, for a total of 5 washes, to obtain precipitate F.

[0081] Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at 110°C; then take it out and place it in a muffle furnace and calcine it at 700°C for 4 hours; then cool it naturally to room temperature to obtain powder G.

[0082] Step S8: Weigh 10g of calcium propionate as the soluble precursor salt of Ca; then dissolve the soluble precursor salt of Ca in 357mL of deionized water to obtain solution H. The Ca in solution H... 2+ The ion concentration was 0.15 mol / L; then powder G was added to solution H, and the temperature was raised to 90℃. The water in solution H was evaporated while stirring to obtain powder I impregnated with Ca.

[0083] Step S9: Transfer powder I to an oven and let it stand and dry overnight at 110°C; then take it out and place it in a muffle furnace and calcine it at 700°C for 4 hours; then cool it naturally to room temperature to obtain the target product, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2. According to the mass percentage, the content of MnO2 is 70% of the total mass of the secondary hydrogen conversion catalyst, the content of CaO is 10% of the total mass of the secondary hydrogen conversion catalyst, the content of WO3 is 1% of the total mass of the secondary hydrogen conversion catalyst, and the content of TiO2 is 19% of the total mass of the secondary hydrogen conversion catalyst.

[0084] Example 5:

[0085] This embodiment presents an iron-free, water-resistant, and sulfur-resistant secondary hydrogen conversion catalyst, which is MnO2-CaO-WO3-TiO2. It comprises four components: MnO2 as an activator, CaO as a sacrificial agent, WO3 as a structural aid, and TiO2 as an anti-sulfur oxide. The four components are, by mass percentage, 65% of the total mass of the secondary hydrogen conversion catalyst, 8% of the total mass of the secondary hydrogen conversion catalyst, 3% of the total mass of the secondary hydrogen conversion catalyst, and 24% of the total mass of the secondary hydrogen conversion catalyst.

[0086] The preparation method of the above-mentioned MnO2-CaO-WO3-TiO2 hydrogen conversion catalyst includes the following steps:

[0087] Step S1: Weigh 44.4g of manganese chloride tetrahydrate as the soluble precursor salt of Mn, and weigh 1.3g of sodium tungstate as the soluble precursor salt of W; then dissolve the soluble precursor salts of Mn and W together in a mixed solution of 338mL of deionized water and 42.2mL of ethanol, and stir until completely dissolved to form solution A. The total ion concentration of Mn and W in solution A is 0.6mol / L.

[0088] Step S2: Weigh 18.3g of commercially available polyethylene glycol PEG4000 as a dispersant; then add the dispersant to solution A and stir until the dispersant is completely dissolved to form solution B. Here, the addition of the dispersant can effectively inhibit the rapid growth of crystals during nucleation and avoid particle aggregation; the molar amount of PEG4000 is 2% of the total molar amount of Mn and W ions.

[0089] Step S3: Weigh 30.7g of tetrabutyl titanate as the soluble precursor salt of Ti; then dissolve the soluble precursor salt of Ti in 920g of ethanol and stir until completely dissolved to form solution C. The mass ratio of solvent (ethanol) to solute (soluble precursor salt of Ti) in solution C is approximately 30:1.

[0090] Step S4: Slowly add solution C dropwise to solution B while stirring solution B vigorously during the addition process; after the addition is complete, continue stirring for 1 hour to form suspension D.

[0091] Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand at 160°C for 36 hours; then let it cool naturally to room temperature to obtain a layered mixture E.

[0092] Step S6: Discard the supernatant of mixture E, separate and remove the lower precipitate; then wash the removed lower precipitate alternately with 250ml of deionized water and 250ml of ethanol, for a total of 5 washes, to obtain precipitate F.

[0093] Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at 105°C; then take it out and place it in a muffle furnace and calcine it at 500°C for 3 hours; then cool it naturally to room temperature to obtain powder G.

[0094] Step S8: Weigh 7.5g of calcium acetate as the soluble precursor salt of Ca; then dissolve the soluble precursor salt of Ca in 214mL of deionized water to obtain solution H. The Ca in solution H... 2+ The ion concentration was 0.2 mol / L; then powder G was added to solution H, and the temperature was raised to 90℃. The water in solution H was evaporated while stirring to obtain powder I impregnated with Ca.

[0095] Step S9: Transfer powder I to an oven and let it stand and dry overnight at 105°C; then take it out and place it in a muffle furnace and calcine it at 500°C for 3 hours; then cool it naturally to room temperature to obtain the target product, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2. According to the mass percentage, the content of MnO2 is 65% of the total mass of the secondary hydrogen conversion catalyst, the content of CaO is 8% of the total mass of the secondary hydrogen conversion catalyst, the content of WO3 is 3% of the total mass of the secondary hydrogen conversion catalyst, and the content of TiO2 is 24% of the total mass of the secondary hydrogen conversion catalyst.

[0096] Example 6:

[0097] This embodiment presents an iron-free, water-resistant, and sulfur-resistant secondary hydroconversion catalyst, which is MnO2-CaO-WO3-TiO2. It comprises four components: MnO2 as an activator, CaO as a sacrificial agent, WO3 as a structural aid, and TiO2 as an anti-sulfur oxide. The four components are, by mass percentage, 75% of the total mass of the secondary hydroconversion catalyst, 5% of the total mass of the secondary hydroconversion catalyst of MnO2, 2% of the total mass of the secondary hydroconversion catalyst of CaO, 18% of the total mass of the secondary hydroconversion catalyst of WO3, and 18% of the total mass of the secondary hydroconversion catalyst of TiO2.

[0098] The preparation method of the above-mentioned MnO2-CaO-WO3-TiO2 hydrogen conversion catalyst includes the following steps:

[0099] Step S1: Weigh 74.3g of manganese nitrate hexahydrate as the soluble precursor salt of Mn, and weigh 0.6g of ammonium metatungstate as the soluble precursor salt of W; then dissolve the soluble precursor salts of Mn and W together in a mixed solution of 1120mL of deionized water and 186.7mL of ethanol, and stir until completely dissolved to form solution A. The total ion concentration of Mn and W in solution A is 0.2mol / L.

[0100] Step S2: Weigh 10.4g of commercially available polyethylene glycol PEG4000 as a dispersant; then add the dispersant to solution A and stir until the dispersant is completely dissolved to form solution B. Here, the addition of the dispersant can effectively inhibit the rapid growth of crystals during nucleation and avoid particle aggregation; the molar amount of PEG4000 is 1% of the total molar amount of Mn and W ions.

[0101] Step S3: Weigh 23g of tetrabutyl titanate as the soluble precursor salt of Ti; then dissolve the soluble precursor salt of Ti in 184g of ethanol and stir until completely dissolved to form solution C. The mass ratio of solvent (ethanol) to solute (soluble precursor salt of Ti) in solution C is 8:1.

[0102] Step S4: Slowly add solution C dropwise to solution B while stirring solution B vigorously during the addition process; after the addition is complete, continue stirring for 2 hours to form suspension D.

[0103] Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand at 180°C for 24 hours; then let it cool naturally to room temperature to obtain a layered mixture E.

[0104] Step S6: Discard the supernatant of mixture E, separate and remove the lower precipitate; then wash the removed lower precipitate alternately with 250ml of deionized water and 250ml of ethanol, for a total of 5 washes, to obtain precipitate F.

[0105] Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at 150°C; then take it out and place it in a muffle furnace and calcine it at 600°C for 8 hours; then let it cool naturally to room temperature to obtain powder G.

[0106] Step S8: Weigh 6.3g of calcium nitrate as the soluble precursor salt of Ca; then dissolve the soluble precursor salt of Ca in 267mL of deionized water to obtain solution H. The Ca in solution H... 2+ The ion concentration was 0.1 mol / L; then powder G was added to solution H, and the temperature was raised to 90℃. The water in solution H was evaporated while stirring to obtain powder I impregnated with Ca.

[0107] Step S9: Transfer powder I to an oven and let it stand and dry overnight at 150°C; then take it out and place it in a muffle furnace and calcine it at 600°C for 8 hours; then cool it naturally to room temperature to obtain the target product, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2. According to the mass percentage, the content of MnO2 is 75% of the total mass of the secondary hydrogen conversion catalyst, the content of CaO is 5% of the total mass of the secondary hydrogen conversion catalyst, the content of WO3 is 2% of the total mass of the secondary hydrogen conversion catalyst, and the content of TiO2 is 18% of the total mass of the secondary hydrogen conversion catalyst.

[0108] To further illustrate the concentration of secondary hydrogen and the conversion rate of secondary hydrogen generated by the MnO2-CaO-WO3-TiO2 catalyst of the present invention, experiments were conducted.

[0109] The MnO2-CaO-WO3-TiO2 catalyst prepared from Examples 1-6 and its commercial use Three g of each catalyst was taken and subjected to the following processes: It was placed in a positive and negative hydrogen conversion furnace immersed in liquid nitrogen, and a mixture of 75% positive hydrogen and 25% negative hydrogen was introduced, with the hydrogen flow rate controlled by a flow meter; the hydrogen gas after the reaction was analyzed by gas chromatography to determine the negative hydrogen content, and the positive and negative hydrogen conversion rates were calculated. Table 1 shows the positive and negative hydrogen conversion catalysts MnO2-CaO-WO3-TiO2 prepared in Examples 1-6 and their commercial applications. The concentration of secondary hydrogen and the conversion rate of primary and secondary hydrogen were determined when the hydrogen flow rate was fixed at 90 ml / min and the reaction temperature was 77 K.

[0110] Table 1. MnO2-CaO-WO3-TiO2 catalysts prepared in Examples 1-6 and their commercial applications. The concentration of secondary hydrogen and the conversion rate of primary and secondary hydrogen at a fixed hydrogen flow rate of 90 ml / min and a reaction temperature of 77 K.

[0111]

[0112]

[0113] As shown in Table 1, the MnO2-CaO-WO3-TiO2 catalyst prepared by the method of this invention exhibits high reactivity and excellent water and sulfur resistance. Under the conditions of a reaction temperature of 77K, a gas flow rate of 90 ml / min, a catalyst loading of 3 g, and raw materials containing 500 ppm H2O and 200 ppm SO2, the conversion rates of n- and secondary hydrogen are all above 95%, and the outlet secondary hydrogen concentration is greater than 48%. Compared with commercially available catalysts... The catalyst exhibits superior reactivity in the conversion of hydrogen containing H2O and SO2.

[0114] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A water-resistant and sulfur-resistant secondary hydrogen conversion catalyst, characterized in that... The secondary hydroconversion catalyst is MnO2-CaO-WO3-TiO2, comprising four components: MnO2 as an activator, CaO as a sacrificial agent, WO3 as a structural aid, and TiO2 as an antioxidant. The content of MnO2, CaO, WO3, and TiO2 is 60-70% of the total mass of the catalyst, 6-8% of the catalyst, 2-3% of the catalyst, and 19-32% of the catalyst, respectively, by mass percentage. The preparation method of the secondary hydroconversion catalyst includes the following steps: Step S1: Dissolve the required amounts of soluble precursor salts of Mn and W together in a mixed solution of deionized water and ethanol to form solution A; Step S2: Add dispersant to solution A and stir until the dispersant is completely dissolved to form solution B; Step S3: Dissolve the required amount of the soluble precursor salt of Ti in ethanol to form solution C; Step S4: Slowly add solution C dropwise to solution B while vigorously stirring solution B during the addition process; after the addition is complete, continue stirring for a period of time to form suspension D; Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand and react for a period of time at a certain temperature; then let it cool naturally to room temperature to obtain the mixture E; Step S6: Discard the supernatant of mixture E and remove the lower precipitate; then wash the removed lower precipitate alternately with deionized water and ethanol to obtain precipitate F; Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at a certain temperature; then calcine it at a certain temperature for a period of time; and then cool it naturally to room temperature to obtain powder G; Step S8: Dissolve the required amount of soluble precursor salt of Ca in deionized water to obtain solution H; then add powder G to solution H, heat to a certain temperature, and evaporate the water in solution H under stirring to obtain powder I impregnated with Ca. Step S9: Transfer powder I to an oven and let it stand and dry overnight at a certain temperature; then calcine it at a certain temperature for a period of time; and then cool it naturally to room temperature to obtain the target material, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2.

2. A method for preparing the water-resistant and sulfur-resistant secondary hydrogen conversion catalyst according to claim 1, characterized in that... Includes the following steps: Step S1: Dissolve the required amounts of soluble precursor salts of Mn and W together in a mixed solution of deionized water and ethanol to form solution A; Step S2: Add dispersant to solution A and stir until the dispersant is completely dissolved to form solution B; Step S3: Dissolve the required amount of the soluble precursor salt of Ti in ethanol to form solution C; Step S4: Slowly add solution C dropwise to solution B while vigorously stirring solution B during the addition process; after the addition is complete, continue stirring for a period of time to form suspension D; Step S5: Pour the suspension D into a hydrothermal reactor, then transfer it to an oven and let it stand and react for a period of time at a certain temperature; then let it cool naturally to room temperature to obtain the mixture E; Step S6: Discard the supernatant of mixture E and remove the lower precipitate; then wash the removed lower precipitate alternately with deionized water and ethanol to obtain precipitate F; Step S7: Transfer the precipitate F to an oven and let it stand and dry overnight at a certain temperature; then calcine it at a certain temperature for a period of time. After naturally cooling to room temperature, powder G is obtained; Step S8: Dissolve the required amount of soluble precursor salt of Ca in deionized water to obtain solution H; then add powder G to solution H, heat to a certain temperature, and evaporate the water in solution H under stirring to obtain powder I impregnated with Ca. Step S9: Transfer powder I to an oven and let it stand and dry overnight at a certain temperature; then calcine it at a certain temperature for a period of time. After naturally cooling to room temperature, the target material, namely the secondary hydrogen conversion catalyst MnO2-CaO-WO3-TiO2, is obtained.

3. The method for preparing a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst according to claim 2, characterized in that... In step S1, the soluble precursor salt of Mn is selected from at least one of manganese nitrate and manganese chloride; the soluble precursor salt of W is selected from at least one of ammonium metatungstate, ammonium tungstate, and sodium tungstate; the volume ratio of deionized water to ethanol in the mixed solution is (15-3):1; the total ion concentration of Mn and W in solution A is 0.2-3 mol / L.

4. The method for preparing a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst according to claim 2, characterized in that... In step S2, PEG4000 is selected as the dispersant, and the number of moles of the dispersant is 0.2 to 3% of the total number of moles of Mn and W ions.

5. The method for preparing a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst according to claim 2, characterized in that... In step S3, the soluble precursor salt of Ti is selected from at least one of tetrabutyl titanate, tetraethyl titanate, and isopropyl titanate; the mass ratio of solvent (ethanol) to solute (soluble precursor salt of Ti) in solution C is (5-30):

1.

6. The method for preparing a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst according to claim 2, characterized in that... In step S4, after the addition is completed, stirring continues for 0.5 to 3 hours; in step S5, the reaction temperature in the oven is 120 to 200°C, and the reaction time is 12 to 36 hours; in steps S7 and S9, the drying temperature in the oven is 100 to 150°C; the calcination temperature is 400 to 700°C, and the calcination time is 3 to 8 hours.

7. The method for preparing a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst according to claim 2, characterized in that... In step S6, the amount of deionized water used is 250 mL, the amount of ethanol used is 250 mL, and the number of times the washing is alternated is 5.

8. The method for preparing a water-resistant and sulfur-resistant secondary hydrogen conversion catalyst according to claim 2, characterized in that... In step S8, the soluble precursor salt of Ca is selected from at least one of calcium nitrate, calcium chloride, calcium acetate, and calcium propionate; Ca in solution H 2+ The ion concentration is 0.05–0.2 mol / L; powder G is added to solution H, and the water in solution H is evaporated to dryness under stirring after the temperature is raised to 90 °C.

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