Multi-component high-activity ortho-parahydrogen conversion catalyst as well as preparation method and application thereof

Abstract

The invention discloses a multi-component high-activity ortho-parahydrogen conversion catalyst and a preparation method and application thereof.The method at least comprises the steps that a five-component catalyst containing Fe, Co and Ni and containing any two kinds of metal of Mn, Mg, Cr, Cu, Zn, Ga, Sn and Al is prepared, the catalyst is prepared through a precipitation method, and the specific steps are as follows: soluble salts of the metal components are dissolved in water and stirred, and a solution A is obtained; preparing a soluble alkaline aqueous solution to obtain a solution B; dropwise adding the solution A into the solution B, or dropwise adding the solution B into the solution A, and carrying out precipitation reaction; controlling the pH value at the end point of the precipitation reaction to be 8-13, and aging for 2-168 hours to obtain a precipitate; and filtering, washing, drying and roasting the precipitate to obtain the multi-component catalyst containing five metal components. The catalyst prepared by the method shows high activity when catalyzing low-temperature conversion of ortho-parahydrogen; the catalyst is simple in preparation process and easy for large-scale production.

Description

Technical Field

[0001] This application relates to a multi-component highly active positive and negative hydrogen conversion catalyst, its preparation method, and its application, belonging to the field of catalyst application technology. Background Technology

[0002] Liquid hydrogen, as a highly efficient liquid fuel and cryogenic cold source, has wide applications in chemical production, aerospace engineering, hydrogen fuel cell vehicles, neutron cooling, and particle detection. The large-scale use of hydrogen energy inevitably raises the question of how to efficiently store liquid hydrogen, which is inextricably linked to the chemical and physical properties of the hydrogen molecule.

[0003] The nuclear spins of the two hydrogen atoms in a hydrogen molecule can be parallel or antiparallel, resulting in two spin isomers: positive (positive) and negative (negative). As the temperature decreases, positive hydrogen spontaneously converts to negative (negative), causing the concentration of negative hydrogen to increase. The heat released during this positive-negative conversion exceeds the latent heat of vaporization of liquid hydrogen, leading to its evaporation. To reduce evaporation losses and the energy consumption of reliquefaction, and to extend the time for lossless storage of liquid hydrogen, the positive-negative conversion must be completed simultaneously with hydrogen liquefaction.

[0004] The natural conversion of ortho and parahydrogen is an extremely slow process, so catalysts are needed to accelerate the conversion rate. It is generally believed that the low-temperature conversion of ortho and parahydrogen involves a magnetic mechanism, where hydrogen atoms are transformed by the non-uniform magnetic field of the catalyst. Transition elements (such as iron, nickel, manganese, and chromium) have unpaired electrons in their 3d or 4f shells, making them a primary research focus for low-temperature conversion catalysts of ortho and parahydrogen, such as Cr₂O₃-Al₂O₃, Cr₂O₃+Ni, Cr(OH)₃, Mn(OH)₄, FeOOH, Co(OH)₃, and Ni(OH)₂. In addition, nano-gold, nano-silver, silicon, and activated carbon are also widely studied as low-temperature conversion catalysts for ortho and parahydrogen.

[0005] Currently, the main catalysts used for the conversion of n- and secondary hydrogen in liquid hydrogen production are hydrated iron oxide catalysts. However, hydrated iron oxide catalysts suffer from problems such as a narrow applicable temperature window and low catalytic activity. Therefore, it remains essential to develop low-temperature n- and secondary hydrogen conversion catalysts with high catalytic activity and simple preparation processes. Summary of the Invention

[0006] This application proposes a multi-component highly active positive and negative hydrogen conversion catalyst, its preparation method, and its application. The catalyst prepared by this method has high activity and the preparation process is simple.

[0007] According to a first aspect of this application, a method for preparing a multi-component highly active positive and negative hydrogen conversion catalyst is provided, the method comprising: (1) Dissolve a soluble metal salt containing Fe, Co, Ni and any two metals from Mn, Mg, Cr, Cu, Zn, Ga, Sn, and Al in water and stir to obtain solution A; (2) Prepare a soluble alkaline aqueous solution, stir, and obtain solution B; (3) Add solution A dropwise to solution B, or add solution B dropwise to solution A, and a precipitation reaction occurs under stirring. (4) Control the pH value at the end point of the precipitation reaction to be between 8 and 13, and age for 2h to 168h to obtain the precipitate; (5) The precipitate is filtered, washed, dried and calcined to obtain the multi-component high-activity ortho-parahydrogen conversion catalyst.

[0008] Optionally, in step (1), the soluble metal salt is at least one of nitrate, sulfate, chloride, and acetate.

[0009] Optionally, in solution A, the ratio of metal atoms in various metal salts is an equimolar ratio.

[0010] Optionally, the soluble metal salt aqueous solution is an aqueous solution with a mass percentage of 1 to 50%.

[0011] Optionally, the soluble metal salt aqueous solution is an aqueous solution with a mass percentage of 5-20%.

[0012] Optionally, in step (2), the soluble alkaline aqueous solution is an aqueous solution of one or a mixture of ammonium carbonate, ammonium bicarbonate, urea, ammonia, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, potassium hydroxide, and sodium hydroxide in any proportion.

[0013] Optionally, the soluble alkaline aqueous solution is an aqueous solution with a mass percentage of 1 to 50%.

[0014] Optionally, the soluble alkaline aqueous solution is an aqueous solution with a mass percentage of 5-30%.

[0015] Optionally, in step (3), the reaction temperature of the precipitation reaction is 5~90℃, preferably 10~80℃.

[0016] Optionally, the temperature of the precipitation reaction is independently selected from any one of 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C.

[0017] Optionally, in step (4), the pH value is between 8 and 12; the aging time is 6 to 96 hours; and the aging method is stirring aging or static aging.

[0018] Optionally, the aging time is independently selected from any one of 96 h, 90 h, 80 h, 70 h, 60 h, 50 h, 30 h, and 10 h.

[0019] Optionally, in step (5), the drying atmosphere is an air atmosphere or an inert gas atmosphere; the inert gas is nitrogen, argon or helium; Preferably, in step (5), the drying temperature is 60~160℃ and the time is 1~48h.

[0020] Optionally, the drying temperature is independently selected from any one of 160°C, 140°C, 120°C, 100°C, and 80°C, and the time is independently selected from any one of 48 h, 42 h, 36 h, 30 h, 24 h, 20 h, 14 h, 10 h, 4 h, and 1 h.

[0021] Preferably, in step (5), the calcination temperature is 140~900℃ and the time is 1~24h.

[0022] Optionally, the roasting temperature is independently selected from any one of 900℃, 800℃, 700℃, 600℃, 500℃, 400℃, 300℃, and 200℃, and the time is independently selected from any one of 24 h, 20 h, 16 h, 10 h, 6 h, and 2 h.

[0023] According to a second aspect of this application, a multi-component highly active secondary hydrogen conversion catalyst is provided, wherein the multi-component highly active secondary hydrogen conversion catalyst is selected from any one of the multi-component highly active secondary hydrogen conversion catalysts prepared according to the above preparation method.

[0024] According to a third aspect of this application, an application of the aforementioned multi-component highly active n- and secondary hydrogen conversion catalyst in catalyzing n- and secondary hydrogen conversion reactions is provided.

[0025] The beneficial effects that this application can produce include: The multi-component metal catalyst of this invention has structural lattice distortion effect, synergistic effect of multiple metal ions and high temperature stability, thus generating more active sites for low-temperature conversion of n- and para-hydrogens, significantly improving the catalyst's n- and para-hydrogen conversion activity; the catalyst preparation process is simple and easy to scale up. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the performance evaluation device for the low-temperature conversion reaction of n- and para-hydrogen in the embodiment described above. Detailed Implementation

[0027] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0028] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0029] The secondary hydrogen content analysis method involved using a multi-component high-activity ortho- and para-hydrogen conversion catalyst activity evaluation device combined with gas chromatography to detect the secondary hydrogen content. (See attached document). Figure 1 .

[0030] Comparative Example 1 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C, and a 10% ferric nitrate aqueous solution was added dropwise until the pH reached 9. The addition was then stopped to obtain an iron-based precipitate. The precipitate was filtered, washed with water until the pH reached approximately 7, and then dried in air at 110°C for 24 hours and calcined in air at 160°C for 6 hours to obtain catalyst #1.

[0031] Comparative Example 2 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C, and a 10% ferric nitrate aqueous solution was added dropwise until the pH reached 9. The addition was then stopped to obtain an iron-based precipitate. The precipitate was filtered, washed with water until the pH reached approximately 7, and then dried in air at 110°C for 24 hours and calcined in air at 600°C for 6 hours to obtain catalyst #2.

[0032] Comparative Example 3 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C, and equimolar amounts of ferric nitrate and gallium nitrate aqueous solutions (both ferric nitrate and gallium nitrate were 10% by mass) were added dropwise until the pH reached 9. The addition was then stopped, resulting in a mixed precipitate containing iron and gallium metal salts. The precipitate was filtered, washed with water until the pH reached approximately 7, and then dried in air at 110°C for 24 hours and calcined in air at 600°C for 6 hours to obtain catalyst #3.

[0033] Example 1 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C. Equivalent molar ratios of ferric nitrate, cobalt nitrate, nickel nitrate, gallium nitrate, and aluminum nitrate solutions (all metal salt solutions were 10% by mass) were added dropwise until pH=9. The addition was then stopped, resulting in a mixed precipitate containing five metal salts. After stirring and aging for 12 hours, the precipitate was filtered, washed with water until pH≈7, and then dried in air at 110°C for 24 hours. Finally, it was calcined in air at 160°C for 6 hours to obtain catalyst #4.

[0034] Example 2 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C. Equivalent molar ratios of ferric nitrate, cobalt nitrate, nickel nitrate, gallium nitrate, and aluminum nitrate solutions (all metal salt solutions were 10% by mass) were added dropwise until pH=9. The addition was then stopped, resulting in a mixed precipitate containing five metal salts. After stirring and aging for 12 hours, the precipitate was filtered, washed with water until pH≈7, and then dried in air at 110°C for 24 hours. Finally, it was calcined in air at 600°C for 6 hours to obtain catalyst #5.

[0035] Example 3 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C. Equivalent molar ratios of ferric chloride, cobalt chloride, nickel chloride, manganese chloride, and tin tetrachloride aqueous solutions (all metal salt solutions were 10% by mass) were added dropwise until the pH reached 9. The addition was then stopped, resulting in a mixed precipitate containing five metal salts. After stirring and aging for 12 hours, the precipitate was filtered, washed with water until the pH reached approximately 7, and then dried in air at 110°C for 24 hours. Finally, the precipitate was calcined in air at 600°C for 6 hours to obtain catalyst #6.

[0036] Example 4 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C. Equivalent molar ratios of ferric nitrate, cobalt nitrate, nickel nitrate, manganese nitrate, and tin tetrachloride aqueous solutions (all metal salt solutions were 10% by mass) were added dropwise until pH=9. The addition was then stopped, resulting in a mixed precipitate containing five metal salts. After stirring and aging for 12 hours, the precipitate was filtered, washed with water until pH≈7, and then dried in air at 110°C for 24 hours. Finally, it was calcined in air at 160°C for 6 hours to obtain catalyst #7.

[0037] Example 5 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C. Equivalent molar ratios of ferric nitrate, cobalt nitrate, nickel nitrate, manganese nitrate, and tin tetrachloride aqueous solutions (all metal salt solutions were 10% by mass) were added dropwise until pH=9. The addition was then stopped, resulting in a mixed precipitate containing five metal salts. After stirring and aging for 12 hours, the precipitate was filtered, washed with water until pH≈7, and then dried in air at 110°C for 24 hours. Finally, it was calcined in air at 600°C for 6 hours to obtain catalyst #8.

[0038] Example 6 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40°C. Equivalent molar ratios of ferric nitrate, cobalt nitrate, nickel nitrate, manganese nitrate, and gallium nitrate aqueous solutions (all metal salt solutions were 10% by mass) were added dropwise until pH=9. The addition was then stopped, resulting in a mixed precipitate containing five metal salts. After stirring and aging for 12 hours, the precipitate was filtered, washed with water until pH≈7, and then dried in air at 110°C for 24 hours. Finally, it was calcined in air at 600°C for 6 hours to obtain catalyst #9.

[0039] Example 7 300g of a 15% sodium hydroxide aqueous solution was placed in a reaction vessel; after sealing, the mixture was stirred and heated to 40℃, and aqueous solutions of ferric nitrate, cobalt nitrate, nickel nitrate, manganese nitrate, and gallium nitrate (all metal salt solutions were 10% by mass) with a metal atomic molar ratio of 2:1:1:1:1 were added dropwise until the pH reached 9, at which point the addition was stopped, resulting in a mixed precipitate containing five metal salts; after stirring and aging for 12h, the precipitate was filtered, washed with water until the pH ≈ 7, and then dried in air at 110℃ for 24h and calcined in air at 600℃ for 6h to obtain catalyst #10.

[0040] Application examples Catalyst activity evaluation in Figure 1 The reaction was performed using the low-temperature conversion evaluation apparatus for n- and secondary hydrogen shown. 0.5 g of catalyst was weighed and placed in the conversion furnace. The furnace was heated to 110 °C and purged with helium at a flow rate of 10 ml / min for 12 h. Heating and purging were then stopped, and the furnace was allowed to cool to room temperature before being placed in a Dewar flask. The Dewar flask was filled with liquid nitrogen, and once the temperature sensor indicated that the liquid nitrogen temperature had been reached, hydrogen was introduced to perform the n- and secondary hydrogen conversion. The converted hydrogen was then analyzed by gas chromatography for secondary hydrogen content. The reaction temperature was 79 K, the reaction pressure was 1.3 atm, and the hydrogen flow rate was 600 ml / min. The experimental results are shown in Table 1.

[0041] Table 1 Comparison of catalytic performance of different catalysts for the conversion of n- and secondary hydrogen

[0042] As shown in Table 1, under the same experimental conditions, the multi-component metal catalysts provided in the embodiments of the present invention all exhibited excellent catalytic activity. In particular, the catalysts prepared in Examples 1, 2, 5, 6, and 7 had a secondary hydrogen content >46.0% after the reaction, which was superior to the reference catalyst.

[0043] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a multi-component, highly active, positive and negative hydrogen conversion catalyst, characterized in that, The preparation method includes: (1) Dissolve a soluble metal salt containing Fe, Co, Ni and any two metals from Mn, Mg, Cr, Cu, Zn, Ga, Sn, and Al in water and stir to obtain solution A; (2) Prepare a soluble alkaline aqueous solution, stir, and obtain solution B; (3) Add solution A dropwise to solution B, or add solution B dropwise to solution A, and a precipitation reaction occurs under stirring. (4) Control the pH value at the end point of the precipitation reaction to be between 8 and 13, and age for 2h to 168h to obtain the precipitate; (5) The precipitate is filtered, washed, dried and calcined to obtain the multi-component high-activity ortho-parahydrogen conversion catalyst.

2. The preparation method according to claim 1, characterized in that, In step (1), the soluble metal salt is at least one of nitrate, sulfate, chloride, and acetate. Preferably, in solution A, the ratio of metal atoms in each metal salt is an equimolar ratio.

3. The preparation method according to claim 1, characterized in that, The aqueous solution of soluble metal salt is an aqueous solution with a mass percentage of 1-50%.

4. The preparation method according to claim 1, characterized in that, In step (2), the soluble alkaline aqueous solution is an aqueous solution of one or a mixture of any proportion of ammonium carbonate, ammonium bicarbonate, urea, ammonia, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, potassium hydroxide, and sodium hydroxide.

5. The preparation method according to claim 4, characterized in that, The soluble alkaline aqueous solution is an aqueous solution with a mass percentage of 1-50%.

6. The preparation method according to claim 1, characterized in that, In step (3), the reaction temperature of the precipitation reaction is 5~90℃, preferably 10~80℃.

7. The preparation method according to claim 1, characterized in that, In step (4), the pH value is between 8 and 12; the aging time is 6 to 96 hours; and the aging method is stirring aging or static aging.

8. The preparation method according to claim 1, characterized in that, In step (5), the drying atmosphere is an air atmosphere or an inert gas atmosphere; the inert gas is nitrogen, argon or helium; Preferably, in step (5), the drying temperature is 60~160℃ and the time is 1~48h; Preferably, in step (5), the calcination temperature is 140~900℃ and the time is 1~24h.

9. A multi-component, highly active, positive and negative hydrogen conversion catalyst, characterized in that, The multi-component highly active secondary hydrogen conversion catalyst is selected from any one of the multi-component highly active secondary hydrogen conversion catalysts prepared according to any one of claims 1 to 8.

10. The application of the multi-component highly active n- and secondary hydrogen conversion catalyst according to claim 9 in the catalytic n- and secondary hydrogen conversion reaction.

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