A catalyst for catalyzing the absorption and release of hydrogen by a liquid organic hydrogen carrier and a preparation method thereof

Abstract

The present invention belongs to the fields of hydrogen storage technology and catalytic technology, and specifically relates to a catalyst for catalyzing the absorption and desorption of hydrogen by a liquid organic hydrogen carrier and a preparation method thereof. The catalyst comprises a catalyst carrier and a precious metal active catalytic component loaded on the catalyst carrier, wherein the catalyst carrier is a shaped nano-LaNi5, and the precious metal active catalytic component is Pd or Ru; the loading amount of the precious metal active catalytic component is 0.3%-1% of the mass of the catalyst carrier. Compared with existing precious metal catalyst technology, the present invention has the following advantages: (1) The catalyst of the present invention is a bidirectional catalyst, and the carrier is a nano hydrogen storage material, which can complete the hydrogen absorption and desorption process by itself, and can assist in improving the catalytic performance of the precious metal active catalytic component in the hydrogen absorption and desorption process; (2) The catalyst prepared by the present invention has excellent performance and can achieve or even exceed the hydrogen absorption and desorption catalytic performance of catalysts with higher precious metal loadings while using a small amount of precious metal.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen storage and catalysis, and particularly relates to a catalyst for catalyzing hydrogen absorption and desorption by a liquid organic hydrogen carrier and a preparation method thereof. Background Art

[0002] Liquid organic hydrogen carrier (LOHC) hydrogen storage, a technology that stores hydrogen in an organic liquid, is an emerging hydrogen energy storage method. Compared to solid-state high-pressure hydrogen storage, this technology offers advantages such as higher mass hydrogen storage density, reversible hydrogen absorption and desorption, excellent thermal conductivity, and inherent non-flammability. These advantages suggest that LOHC has a broad potential market for large-scale hydrogen storage and transportation.

[0003] Among the numerous liquid organic hydrogen carriers (LOHCs), N-ethylcarbazole holds the greatest potential for development and market application due to its high mass hydrogen storage density and low hydrogen absorption and desorption temperatures. However, the hydrogen absorption and desorption kinetics of LOHCs are generally poor, and they typically require high loadings of precious metal catalysts such as Ru and Pd. Furthermore, the need for two different catalysts for hydrogen absorption and desorption significantly limits their development and application in the hydrogen energy market.

[0004] Professor Li Xingguo's team at Peking University has successfully developed nano-LaNi5 using a molten salt method. Testing by the team has shown that the prepared nano-LaNi5 is insensitive to water and oxygen and successfully catalyzes the absorption and desorption of hydrogen from N-ethylcarbazole, demonstrating its bidirectional performance. While its performance for hydrogen desorption from N-ethylcarbazole is excellent, comparable to that of Pd-based catalysts, its catalytic performance for hydrogen absorption is relatively poor, requiring more than six hours for hydrogen absorption to reach saturation.

[0005] Therefore, in order to promote the development of N-ethylcarbazole in the field of hydrogen storage and enable its large-scale industrial application, there is an urgent need for efficient and low-cost bidirectional catalysts with excellent hydrogen absorption and desorption catalytic properties. Summary of the Invention

[0006] In order to solve the problems existing in the above-mentioned prior art, one of the objectives of the present invention is to provide a catalyst for catalyzing the absorption and desorption of hydrogen by a liquid organic hydrogen carrier, which can greatly improve the hydrogen absorption performance without sacrificing the efficient desorption performance, thereby greatly shortening the absorption and desorption process time of the liquid organic hydrogen carrier, further meeting the actual large-scale industrial production needs.

[0007] Another object of the present invention is to provide a method for preparing a catalyst for catalyzing the absorption and release of hydrogen by a liquid organic hydrogen carrier.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention provides a catalyst for catalyzing the absorption and release of hydrogen by a liquid organic hydrogen carrier. The catalyst comprises a catalyst carrier and a noble metal active catalytic component supported on the catalyst carrier, wherein the catalyst carrier is a shaped nano-LaNi5; the noble metal active catalytic component is Pd or Ru, and the loading amount of the noble metal active catalytic component is 0.3%-1% of the mass of the catalyst carrier.

[0010] Preferably, the catalyst of the present invention is obtained by impregnating a formed nano-LaNi5 catalyst carrier in a noble metal precursor salt solution, followed by reaction, washing, and drying.

[0011] Further preferably, the shaped nano-LaNi5 catalyst carrier of the present invention is prepared by the following steps:

[0012] Step 1) Place 50-200 mesh LaNi5 alloy powder, dilute ammonium fluoride solution, zirconium oxide balls, and grinding aids into a ball mill;

[0013] Step 2), the ball mill is vacuumed and filled with argon gas for protection, and then the ball mill is turned on and ball milling is performed;

[0014] Step 3) After the ball milling is completed, the obtained product is washed with deionized water, and then centrifuged and vacuum dried to obtain nano-LaNi5 powder;

[0015] Step 4), mixing the nano-LaNi5 powder, binder, oxide carrier and deionized water obtained in step 3) to obtain a viscous mixture, wherein the mass ratio of the nano-LaNi5 powder, binder, oxide carrier and deionized water is (5-10): (2-4): (20-40): (40-50);

[0016] Step 5) placing the viscous mixture obtained in step 4) into an extrusion molding device to obtain a wet strip-shaped catalyst carrier;

[0017] Step 6) placing the wet strip-shaped catalyst carrier obtained in step 5) in a drying device to obtain a dried strip-shaped catalyst carrier, that is, a shaped nano-LaNi5-containing catalyst carrier.

[0018] Further preferably, the noble metal precursor salt solution of the present invention is selected from one of palladium acetate, palladium nitrate, palladium chloride, ruthenium trichloride, ruthenium acetylacetonate or ruthenium acetate solution.

[0019] The present invention provides a method for preparing a catalyst for catalyzing hydrogen absorption and desorption by a liquid organic hydrogen carrier, which comprises the following preparation steps:

[0020] (1) Preparation of shaped nano-LaNi5 catalyst carrier

[0021] Step 1) Place 50-200 mesh LaNi5 alloy powder, dilute ammonium fluoride solution, zirconium oxide balls, and grinding aids into a ball mill;

[0022] Step 2), the ball mill is vacuumed and filled with argon gas for protection, and then the ball mill is turned on and ball milling is performed;

[0023] Step 3) After the ball milling is completed, the obtained product is washed with a large amount of deionized water, and then centrifuged and vacuum dried to obtain nano-LaNi5 powder;

[0024] Step 4), mixing the nano-LaNi5 powder obtained in step 3), a binder, an oxide carrier and deionized water to obtain a viscous mixture;

[0025] Step 5) placing the viscous mixture obtained in step 4) into an extrusion molding device to obtain a wet strip-shaped catalyst carrier;

[0026] Step 6), placing the wet strip catalyst carrier obtained in step 5) in a drying device to obtain a dried strip catalyst carrier, that is, a shaped nano-LaNi5-containing catalyst carrier;

[0027] (II) Preparation of catalysts for catalyzing hydrogen absorption and desorption on liquid organic hydrogen carriers

[0028] A metal precursor salt of Pd or Ru, a metal precursor salt solvent, and the formed nano-LaNi5 catalyst carrier obtained in step (1) are mixed, stirred at a temperature of 20-80°C for 0.5-4h, allowed to stand for 6-12h after stirring, and sequentially washed and dried to obtain a catalyst for catalyzing hydrogen absorption and desorption of a liquid organic hydrogen carrier.

[0029] Further preferably, the mass concentration of the dilute ammonium fluoride solution in step 1) is 5-20%; the grinding aid is selected from one of NaCl, KCl or CaCl2; the mass ratio of the LaNi5 alloy powder to the dilute ammonium fluoride solution, zirconium oxide balls, and grinding aid is 1:(0.5-1):(5-10):(0.5-1); the ball mill speed in step 2) is set to 200-400 rpm, and the ball milling time is 3-6 h.

[0030] Further preferably, the mass ratio of the nano-LaNi5, binder, oxide carrier and deionized water in step 4) is (5~10):(2~4):(20~40):(40~50); the binder is selected from one of sesbania gum powder, dry starch or sodium carboxymethyl cellulose, and the oxide carrier is selected from one of γ-Al2O3, CeO2 or SiO2.

[0031] Further preferably, the length of the dried strip-shaped catalyst carrier of the present invention is 2-8 mm.

[0032] Further preferably, the metal precursor salt of Pd in ​​the present invention is selected from one of palladium acetate, palladium nitrate or palladium chloride; the metal precursor salt of Ru is selected from one of ruthenium trichloride, ruthenium acetylacetonate or ruthenium acetate; and the metal precursor salt solvent is selected from one of hydrochloric acid, acetylacetone or tetrahydrofuran.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) The catalyst of the present invention is a bidirectional catalyst that can catalyze both the hydrogen absorption and dehydrogenation processes of N-ethylcarbazole. In practical applications, the amount of catalyst used can be reduced, thereby lowering the catalyst cost.

[0035] (2) The catalyst of the present invention has excellent performance in both hydrogen absorption and desorption, and can achieve or even exceed the catalytic performance of a catalyst with a higher noble metal loading at a low noble metal loading.

[0036] (3) The preparation method of the present invention is simple, can be produced in large quantities, and is easy to promote and use in industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a physical picture of the 0.5% Pd / LaNi5 catalyst prepared in Example 1 of the present invention;

[0038] Figure 2 The hydrogen absorption kinetic curves of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 of the present invention are shown;

[0039] Figure 3 The hydrogen release kinetic curves of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 of the present invention are shown;

[0040] Figure 4 Schematic diagram of the device for testing the hydrogen absorption and desorption kinetic curves of liquid organic hydrogen carriers in the present invention. DETAILED DESCRIPTION

[0041] The present invention is further described in detail with specific examples below.

[0042] The present invention provides a catalyst for catalyzing hydrogen absorption and desorption by a liquid organic hydrogen carrier. The catalyst comprises a catalyst carrier and a precious metal active catalytic component supported on the catalyst carrier. The catalyst carrier is a shaped catalyst carrier containing nano-LaNi5; the precious metal active catalytic component is Pd or Ru. The catalyst is obtained by immersing the shaped catalyst carrier containing nano-LaNi5 in a precious metal precursor salt solution, reacting, washing, and drying.

[0043] The commercially available LaNi5 alloy powder and 1% Pd / Al2O3 catalyst used in the present invention can be purchased through commercial channels. Example

[0044] (1) 10g of commercially available 100-mesh LaNi5 alloy powder, 5g of a 20% by mass ammonium fluoride dilute solution, 100g of zirconium oxide balls, and 5g of NaCl were placed in a ball mill. The mill was then evacuated and filled with argon gas for protection. The mill was then turned on, the speed set to 300rpm, and the milling was continued for 3h to obtain a ball milled product. The obtained ball milled product was washed three times with deionized water and centrifuged in a centrifuge. After filtering off the upper liquid, the product was dried at 80℃ under vacuum for 8h to obtain nano-LaNi5 powder.

[0045] (2) Weigh 5 g of the nano-LaNi5 powder obtained above, and then weigh 2 g of sesbania rubber powder, 45 g of γ-Al2O3 and 40 mL of deionized water. Put the weighed materials into a beaker and mix and stir for 15 minutes. After stirring evenly, knead them into a ball, put them into an extruder, and set the speed to 120 rpm. Extrude to obtain a 4-6 mm long strip-shaped wet-molded catalyst carrier containing nano-LaNi5, and then dry it in a boiling dryer at 60°C for 3 hours for use.

[0046] (3) Add 0.316 g of palladium acetate and 100 mL of tetrahydrofuran to a beaker, and stir magnetically at 60°C for 30 min. Add the shaped nano-LaNi5 catalyst carrier dried in step (2) to the beaker, continue stirring magnetically for 2 h, let it stand for 8 h, and then dry it in an oven at 120°C to prepare a 0.3% Pd / LaNi5 catalyst.

[0047] The 0.3% Pd / LaNi5 catalyst was evaluated for its catalytic performance in the absorption and desorption of N-ethylcarbazole. The absorption reaction was complete within 1.6 hours at 180°C and 8 MPa H₂, and the corresponding desorption reaction was capable of releasing nearly 99% of hydrogen within 4 hours at 200°C and 0.1 MPa H₂. The apparatus for testing the kinetic curves of hydrogen absorption and desorption of liquid organic hydrogen carriers is available at [see figure 1]. Figure 4 . Example

[0048] (1) 20g of commercially available 200-mesh LaNi5 alloy powder, 10g of a 20% by mass ammonium fluoride dilute solution, 200g of zirconium oxide balls, and 10g of KCl were placed in a ball mill. The ball mill was evacuated and filled with argon gas for protection. The ball mill was then turned on and the speed was set to 300rpm. The ball mill was milled for 3 hours to obtain a ball milled product. The ball milled product was washed three times with deionized water and centrifuged in a centrifuge. After filtering off the upper liquid, it was dried at 80℃ under vacuum for 8 hours to obtain nano-LaNi5 powder.

[0049] (2) Weigh 10g of the nano-LaNi5 powder obtained above, and then weigh 2g of dry starch, 40g of CeO2 and 40g of deionized water. Put the weighed materials into a beaker and mix and stir for 15 minutes. After stirring evenly, knead them into a ball, put them into an extruder, and set the speed to 120rpm. Extrude to obtain a 4~6mm long strip-shaped wet-molded nano-LaNi5 catalyst carrier, and then dry it in a boiling dryer at 60℃ for 3h for use.

[0050] (3) Add 0.527 g of palladium acetate and 100 mL of tetrahydrofuran to a beaker and stir magnetically at 60 °C for 30 min. Add the catalyst support dried in step 1 to the beaker and continue stirring magnetically for 2 h. Allow to stand for 8 h and then dry in an oven at 120 °C to prepare a 0.5% Pd / LaNi5 catalyst.

[0051] The 0.5% Pd / LaNi5 catalyst was evaluated for its catalytic performance in catalyzing the absorption and desorption of N-ethylcarbazole. The absorption reaction was complete within 1.5 hours at 180°C and 8 MPa of H₂. The corresponding desorption reaction, at 200°C and 0.1 MPa of H₂, achieved near-99% hydrogen release within 3.1 hours. The apparatus used to test the hydrogen absorption and desorption kinetics of the liquid organic hydrogen carrier was the same as that used in Example 1. Example

[0052] (1) Place 10g of commercially available 50-mesh LaNi5 alloy powder, 5g of a 20% by mass ammonium fluoride dilute solution, 100g of zirconium oxide balls, and 5g of CaCl2 into a ball mill. The mill is then evacuated and filled with argon for protection. The mill is then turned on, the speed set to 300rpm, and the mill is milled for 3h to obtain a ball milled product. The ball milled product is washed three times with deionized water and centrifuged in a centrifuge. After filtering off the upper liquid, the product is dried at 80℃ under vacuum for 8h to obtain nano-LaNi5 powder.

[0053] (2) Weigh 5 g of the nano-LaNi5 powder obtained above, and then weigh 2 g of sodium carboxymethyl cellulose, 45 g of SiO2 and 40 g of deionized water. Put the weighed materials into a beaker and mix and stir for 15 minutes. After stirring evenly, knead them into a ball, put them into an extruder, and set the speed to 120 rpm. Extrude to obtain a 4-6 mm long strip-shaped wet-molded LaNi5 catalyst carrier, and then dry it in a boiling dryer at 60 ° C for 4 hours for use.

[0054] (3) Add 1.054 g of ruthenium trichloride and 100 mL of tetrahydrofuran to a beaker and stir magnetically at 60°C for 30 min. Add the catalyst support dried in step (2) to the beaker and continue stirring magnetically for 4 h. Allow the mixture to stand for 12 h and then dry in an oven at 80°C to prepare a 1% Ru / LaNi5 catalyst.

[0055] The 1% Ru / LaNi5 catalyst was evaluated for its catalytic performance in catalyzing the absorption and desorption of N-ethylcarbazole. The absorption reaction was complete within 1.3 hours at 180°C and 8 MPa H₂. The corresponding desorption reaction, at 200°C and 0.1 MPa H₂, achieved near-99% hydrogen release within 2.5 hours. The apparatus used to test the hydrogen absorption and desorption kinetics of the liquid organic hydrogen carrier was the same as that used in Example 1.

[0056] Comparative Example

[0057] Commercially available 1% Pd / Al2O3 (Shaanxi Kaida Chemical Co., Ltd.) was used as the catalyst. The hydrogen absorption and desorption test conditions and testing apparatus were the same as in Example 1. The hydrogen absorption reaction was complete within 2.5 hours at 180°C and 8 MPa H2, while the corresponding desorption reaction achieved near 99% hydrogen release within 6.5 hours at 200°C and 0.1 MPa H2. Although the commercially available 1% Pd / Al2O3 catalyst had a higher precious metal loading than the 0.3% Pd / LaNi5 catalyst in Example 1, its hydrogen absorption and dehydrogenation performance remained significantly inferior to those in Example 1.

[0058] Comparative Example

[0059] (1) Weigh 2 g of sesbania rubber powder, 50 g of γ-Al2O3 and 40 g of deionized water, put the weighed materials into a beaker, mix and stir for 15 min, stir evenly and knead into a ball, put it into an extruder, set the speed to 120 rpm, extrude to obtain 4-6 mm long strips of γ-Al2O3 carrier, and then dry them in a boiling dryer at 60 ° C for 3 h for use.

[0060] (2) Add 0.316 g of palladium acetate and 100 mL of tetrahydrofuran to a beaker and stir magnetically at 60 °C for 30 min. Add the strip-shaped γ-Al2O3 carrier dried in step (1) to the beaker and continue stirring magnetically for 2 h. Allow the mixture to stand for 8 h and then dry in an oven at 120 °C to prepare a 0.3% Pd / Al2O3 catalyst.

[0061] The 0.3% Pd / Al2O3 catalyst was evaluated for its ability to catalyze the absorption and desorption of hydrogen by N-ethylcarbazole. The absorption and desorption test conditions and test apparatus were the same as those in Example 1. The absorption reaction was complete within 2.5 hours at 180°C and 8 MPa H2, while the desorption reaction was capable of releasing nearly 99% of hydrogen within 8.5 hours at 200°C and 0.1 MPa H2. Compared to Example 1, the carrier lacked the nano-LaNi5 component, and the comparative catalyst exhibited slightly inferior hydrogen absorption performance, while its dehydrogenation performance significantly differed from that of the catalyst in Example 1. When the catalyst carrier contained nano-LaNi5, the active component Pd had a significantly lower dehydrogenation performance than the hydrogen-containing organic liquid carrier (H x -LOHC, x=0-12) to activate the C-H bonds in the catalyst, while nano-LaNi5 assists the dissociation and transfer of hydrogen. The synergistic effect of the two allows the rapid release of free hydrogen, so the dehydrogenation performance will be greatly improved. When the catalyst carrier does not contain nano-LaNi5, it cannot effectively form the release channel of H2, so the dehydrogenation performance will be significantly different.

[0062] Comparative Example

[0063] (1) Place 10g of commercially available 100-mesh LaNi5 alloy powder, 100g of zirconia balls, and 5g of NaCl into a ball mill. Evacuate the mill and fill it with argon. Then, turn on the ball mill, set the speed to 300rpm, and mill for 3h. Wash the milled product three times with deionized water and centrifuge it. After filtering off the upper liquid, dry it at 80℃ under vacuum for 8h to obtain nano-LaNi5 powder.

[0064] (2) Weigh 5 g of the nano-LaNi5 powder obtained above, and then weigh 2 g of sesbania rubber powder, 45 g of γ-Al2O3 and 40 g of deionized water. Put the weighed materials into a beaker and mix and stir for 15 minutes. After stirring evenly, knead them into a ball. Put it into an extruder and set the speed to 120 rpm. Extrude to obtain a 4-6 mm long strip of wet γ-Al2O3 carrier, and then dry it in a boiling dryer at 60 ° C for 3 hours for use.

[0065] (3) Add 0.316 g of palladium acetate and 100 mL of tetrahydrofuran to a beaker, and stir magnetically at 60°C for 30 min. Add the catalyst support dried in step (2) to the beaker, continue stirring magnetically for 2 h, let it stand for 8 h, and then dry it in an oven at 120°C to prepare a 0.3% Pd / LaNi5 catalyst.

[0066] The 0.3% Pd / LaNi5 catalyst was evaluated for its performance in catalyzing the absorption and desorption of hydrogen by N-ethylcarbazole. The hydrogen absorption and desorption test conditions and the test apparatus were the same as those in Example 1. The hydrogen absorption reaction was able to be completed in 1.8 hours under the conditions of 180°C and 8 MPa H2, and the corresponding desorption reaction was able to release nearly 99% of hydrogen in 5 hours under the conditions of 200°C and 0.1 MPa H2. Compared with Example 1, no dilute ammonium fluoride solution was added during the ball milling process, and the comparative catalyst was slightly inferior to the catalyst in Example 1 in terms of hydrogen absorption and dehydrogenation performance. The dilute ammonium fluoride solution can form a loose LaF3 and a Ni-rich sub-surface layer on LaNi5, while the surface structure becomes loose and cracks are increased. This not only improves the nano-crystallization efficiency of LaNi5, but also the Ni-rich sub-surface layer contributes to the dissociation of adsorbed H2. Without the addition of the dilute ammonium fluoride solution, the above effective gains cannot be obtained, so the hydrogen absorption and dehydrogenation performances are slightly worse.

[0067] Comparative Example

[0068] (1) 10 g of commercially available 100-mesh LaNi5 alloy powder, 5 g of 20% by mass ammonium fluoride dilute solution, 100 g of zirconia balls and 5 g of NaCl were placed in a ball mill, and the ball mill was evacuated and filled with argon for protection. Then, the ball mill was turned on, the speed was set to 300 rpm, and the ball milling was carried out for 3 h to obtain a ball milling product; the ball milling product obtained above was washed with deionized water for 3 times and then centrifuged in a centrifuge. After filtering off the upper liquid, it was dried at 80 ° C under vacuum for 8 h to obtain nano-LaNi5 powder.

[0069] (2) Weigh 5 g of the nano-LaNi5 powder obtained above, then weigh 5 g of sesbania rubber powder, 95 g of γ-Al2O3 and 40 g of deionized water, put the weighed materials into a beaker, mix and stir for 15 minutes, stir evenly and knead into a ball, put it into an extruder, and set the speed to 120 rpm. Extrude to obtain a 4-6 mm long wet strip of γ-Al2O3 carrier, and then dry it in a boiling dryer at 60 ° C for 3 hours for use.

[0070] (3) Add 0.316 g of palladium acetate and 100 mL of tetrahydrofuran to a beaker and stir magnetically at 60°C for 30 min. Add the catalyst support dried in step (2) to the beaker and continue stirring magnetically for 2 h. Allow the mixture to stand for 8 h and then dry in an oven at 120°C to prepare a 0.3% Pd / Al2O3 catalyst.

[0071] The 0.3% Pd / Al2O3 catalyst was evaluated for its ability to catalyze the absorption and desorption of hydrogen by N-ethylcarbazole. The absorption and desorption test conditions and test apparatus were the same as those in Example 1. The hydrogen absorption reaction was complete within 3 h at 180°C and 8 MPa H2, and the corresponding desorption reaction was capable of releasing nearly 99% of hydrogen within 8 h at 200°C and 0.1 MPa H2. Compared with Example 1, the amount of binder and oxide support added during the preparation of this comparative catalyst was greater. The test results showed that both the hydrogen absorption and dehydrogenation performance were significantly lower than those of Example 1. This is because when the binder and oxide support are excessive, the LaNi5 content is small and too dispersed, and the partially dissociated H cannot be effectively released through the LaNi5, increasing the competitive adsorption effect of H2.

[0072] Comparative Example

[0073] (1) Place 10g of commercially available LaNi5 alloy powder, 5g of a 20% by mass dilute ammonium fluoride solution, 100g of zirconium oxide balls, and 5g of NaCl into a ball mill. The mill is then evacuated and filled with argon gas for protection. The mill is then turned on, set to a speed of 300rpm, and milled for 3h to obtain a ball milled product. The ball milled product is washed three times with deionized water and centrifuged in a centrifuge. After filtering off the upper liquid, it is dried at 80°C under vacuum for 8h to obtain nano-LaNi5 powder.

[0074] (2) Weigh 5 g of the nano-LaNi5 powder obtained above, and then weigh 2 g of sesbania rubber powder, 45 g of MgAl2O4 and 40 g of deionized water. Put the weighed materials into a beaker and mix and stir for 15 minutes. After stirring evenly, knead them into a ball. Put it into an extruder and set the speed to 120 rpm. Extrude to obtain a 4-6 mm long strip MgAl2O4 carrier, and then dry it in a boiling dryer at 60 ° C for 3 hours for use.

[0075] (3) Add 0.527 g of palladium acetate and 100 mL of tetrahydrofuran to a beaker and stir magnetically at 60 °C for 30 min. Add the catalyst support dried in step 1 to the beaker and continue stirring magnetically for 2 h. Allow the mixture to stand for 8 h and then dry in an oven at 120 °C to prepare a 0.5% Pd / MgAl2O4 catalyst.

[0076] The 0.5% Pd / MgAl2O4 catalyst was evaluated for its catalytic performance in catalyzing the absorption and desorption of N-ethylcarbazole. The absorption and desorption test conditions and test apparatus were the same as in Example 1. The hydrogen absorption reaction did not reach saturation after 6 hours at 180°C and 8 MPa H2, while the corresponding desorption reaction failed to reach near 99% hydrogen release after 10 hours at 200°C and 0.1 MPa H2. Compared to Example 2, the oxide support was modified, and the comparative catalyst exhibited poor hydrogen absorption and dehydrogenation performance. This may be because the basic sites provided by MgAl2O4 reduced the number of acidic sites, thereby weakening the adsorption and dissociation of H2 from N-ethylcarbazole, preventing it from forming an effective dissociated H transport channel with LaNi5, resulting in a decrease in the catalyst's hydrogen absorption and desorption performance.

[0077] The above description is only a preferred embodiment of the present invention and does not limit the invention. It should be noted that for those skilled in the art, under the technical enlightenment provided by the present invention, other equivalent improvements can be made, all of which can achieve the purpose of the present invention and should be considered as the scope of protection of the present invention.

Claims

1. A catalyst for catalyzing the absorption and release of hydrogen by a liquid organic hydrogen carrier, the catalyst comprising a catalyst carrier and a noble metal active catalytic component supported on the catalyst carrier, characterized in that: The catalyst carrier is a shaped nano-LaNi5 catalyst carrier; the noble metal active catalytic component is Pd or Ru, and the loading amount of the noble metal active catalytic component is 0.3%-1% of the mass of the catalyst carrier; The shaped nano-LaNi5 catalyst carrier is prepared by the following steps: Step 1) Place 50-200 mesh LaNi5 alloy powder, dilute ammonium fluoride solution, zirconium oxide balls, and grinding aids into a ball mill; Step 2), the ball mill is vacuumed and filled with argon gas for protection, and then the ball mill is turned on and ball milling is performed; Step 3) After the ball milling is completed, the obtained product is washed with deionized water, and then centrifuged and vacuum dried to obtain nano-LaNi5 powder; Step 4), mixing the nano-LaNi5 powder, binder, oxide carrier and deionized water obtained in step 3) to obtain a viscous mixture, wherein the mass ratio of the nano-LaNi5 powder, binder, oxide carrier and deionized water is (5-10): (2-4): (20-40): (40-50); Step 5) placing the viscous mixture obtained in step 4) into an extrusion molding device to obtain a wet strip-shaped catalyst carrier; Step 6), placing the wet strip catalyst carrier obtained in step 5) in a drying device to obtain a dried strip catalyst carrier, that is, a shaped nano-LaNi5-containing catalyst carrier; Wherein, the oxide carrier is one of γ-Al2O3, CeO2 or SiO2.

2. The catalyst for catalyzing hydrogen absorption and desorption of a liquid organic hydrogen carrier according to claim 1, characterized in that: The catalyst is obtained by immersing a formed nano-LaNi5 catalyst carrier in a noble metal precursor salt solution, and then reacting, washing and drying.

3. The catalyst for catalyzing hydrogen absorption and desorption of a liquid organic hydrogen carrier according to claim 2, characterized in that: The noble metal precursor salt solution is selected from one of palladium acetate, palladium nitrate, palladium chloride, ruthenium trichloride, ruthenium acetylacetonate or ruthenium acetate solution.

4. The catalyst for catalyzing hydrogen absorption and desorption by a liquid organic hydrogen carrier according to claim 3, characterized in that: The mass concentration of the dilute ammonium fluoride solution in step 1) is 5-20%; the grinding aid is selected from one of NaCl, KCl or CaCl2; the mass ratio of the LaNi5 alloy powder to the dilute ammonium fluoride solution, zirconium oxide balls, and grinding aid is 1:(0.5-1):(5-10):(0.5-1); The binder is one of sesbania gum powder, dry starch or sodium carboxymethyl cellulose.

5. A method for preparing the catalyst for catalyzing hydrogen absorption and desorption of a liquid organic hydrogen carrier as claimed in claim 1, characterized in that: The preparation steps are as follows: (1) Preparation of shaped nano-LaNi5 catalyst carrier Step 1) Place 50-200 mesh LaNi5 alloy powder, dilute ammonium fluoride solution, zirconium oxide balls, and grinding aids into a ball mill; Step 2), the ball mill is vacuumed and filled with argon gas for protection, and then the ball mill is turned on and ball milling is performed; Step 3) After the ball milling is completed, the obtained product is washed with a large amount of deionized water, and then centrifuged and vacuum dried to obtain nano-LaNi5 powder; Step 4), mixing the nano-LaNi5 powder obtained in step 3), a binder, an oxide carrier and deionized water to obtain a viscous mixture; wherein the mass ratio of the nano-LaNi5, the binder, the oxide carrier and the deionized water is (5-10): (2-4): (20-40): (40-50), and the oxide carrier is selected from one of γ-Al2O3, CeO2 or SiO2; Step 5) placing the viscous mixture obtained in step 4) into an extrusion molding device to obtain a wet strip-shaped catalyst carrier; Step 6), placing the wet strip catalyst carrier obtained in step 5) in a drying device to obtain a dried strip catalyst carrier, that is, a shaped nano-LaNi5-containing catalyst carrier; (II) Preparation of catalysts for catalyzing hydrogen absorption and desorption on liquid organic hydrogen carriers A metal precursor salt of Pd or Ru, a metal precursor salt solvent, and the formed nano-LaNi5 catalyst carrier obtained in step (1) are mixed, stirred at a temperature of 20-80°C for 0.5-4h, allowed to stand for 6-12h after stirring, and sequentially washed and dried to obtain a catalyst for catalyzing hydrogen absorption and desorption of a liquid organic hydrogen carrier.

6. The method according to claim 5, characterized in that: The mass concentration of the dilute ammonium fluoride solution in step 1) is 5-20%; the grinding aid is selected from one of NaCl, KCl or CaCl2; the mass ratio of the LaNi5 alloy powder to the dilute ammonium fluoride solution, zirconium oxide balls, and grinding aid is 1:(0.5-1):(5-10):(0.5-1); the ball mill speed in step 2) is set to 200-400 rpm, and the ball milling time is 3-6 hours.

7. The method according to claim 5, characterized in that: The binder is selected from one of sesbania gum powder, dry starch or sodium carboxymethyl cellulose.

8. The method according to claim 5, characterized in that: The length of the dried strip catalyst carrier is 2-8 mm.

9. The method according to claim 5, characterized in that: The metal precursor salt of Pd is selected from one of palladium acetate, palladium nitrate or palladium chloride; the metal precursor salt of Ru is selected from one of ruthenium trichloride, ruthenium acetylacetonate or ruthenium acetate; the metal precursor salt solvent is selected from one of hydrochloric acid, acetylacetone or tetrahydrofuran; the active catalytic component loading in the metal precursor salt of Pd or Ru is 0.3%~1% of the mass of the strip catalyst support.

Images