Use of Lithium Magnesium Nitrogen Hydrogen Material

Abstract

The present invention discloses a use of a lithium magnesium nitride hydrogen material, belonging to the technical field of organic liquid hydrogen storage. This use is as a co-catalyst during the hydrogenation reaction of a liquid organic hydrogen storage material. Among them, the main catalyst during the hydrogenation reaction of the liquid organic hydrogen storage material is a noble metal catalyst. During the hydrogenation reaction process of the liquid organic hydrogen storage material, the dehydrogenated lithium magnesium nitride hydrogen material can be used as a co-catalyst for the noble metal catalyst to activate hydrogen molecules and provide active hydrogen for the hydrogenation reaction. Through the synergistic reaction of the catalyst and the co-catalyst, the hydrogenation reaction rate of the noble metal catalyst for catalyzing the organic liquid hydrogen storage material can be effectively improved, the hydrogenation saturation time can be shortened, the energy consumption can be reduced, which helps to reduce the usage amount of noble metals and save costs.

Description

Technical Field

[0001] The present invention relates to the use of a lithium magnesium nitrogen hydrogen material, belonging to the technical field of organic liquid hydrogen storage. Background Art

[0002] The principle of the organic liquid hydrogen storage technology is to realize the storage and release of hydrogen by means of the reversible hydrogenation and dehydrogenation reactions of some liquid organic hydrogen storage carriers (Liquid Organic Hydrogen Carriers, LOHC) with unsaturated bonds and hydrogen. Its advantages are that it is in a liquid form at normal temperature and pressure, has a high hydrogen storage mass density, and can undergo hydrogenation and dehydrogenation reactions only under certain catalytic conditions. Therefore, it can transport hydrogen energy safely at normal temperature and pressure by means of the existing infrastructure.

[0003] Currently, the commonly used hydrogenation catalysts in the process of organic hydrogen storage liquid hydrogen storage are mainly expensive noble metal catalysts, such as palladium-based catalysts, platinum-based catalysts, ruthenium-based catalysts, and rhodium-based catalysts. As the active center, noble metals have the advantages of high activity, low requirements for temperature and pressure, etc. However, the high cost limits their wide application. In the commercialization process of the organic hydrogen carrier hydrogen storage and release technology, reducing costs is the only way. How to reduce the amount of noble metal catalysts used in the operation of organic hydrogen storage liquids has become an urgent problem to be solved in the technical field of organic liquid hydrogen storage. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a new use of the lithium magnesium nitrogen hydrogen material, which can reduce the amount of noble metal catalysts used in the operation of organic hydrogen storage liquids.

[0005] The use of the lithium magnesium nitrogen hydrogen material is: as a co-catalyst for the hydrogenation reaction of a liquid organic hydrogen storage material, and the main catalyst in the hydrogenation reaction is a noble metal catalyst.

[0006] The use of the lithium magnesium nitrogen hydrogen material provided by the present application helps to improve the hydrogenation and dehydrogenation kinetic performance and reactant conversion efficiency of the organic liquid hydrogen storage medium by using a co-catalyst, enhances the catalytic reaction activity of the catalyst, and further reduces the amount of noble metal catalysts, thereby reducing the catalyst cost.

[0007] Further, the liquid organic hydrogen storage material is selected from at least one of aromatic compounds and nitrogen-containing heterocyclic compounds.

[0008] Further, the aromatic compound is selected from at least one of benzene, toluene, dibenzyltoluene, naphthalene, and naphthalene derivatives.

[0009] Preferably, the nitrogen-containing heterocyclic compound is selected from at least one of carbazole, N-ethylcarbazole, N-propylcarbazole, indole, 1-methylindole, and 2-methylindole. The hydrogenation temperature of the above-preferred nitrogen-containing heterocyclic compound matches the hydrogenation temperature of lithium magnesium nitride hydride and the temperature that has a co-catalytic effect on the hydrogenation reaction, and can simultaneously achieve the effects of co-catalysis and maintaining a high hydrogen storage density in the whole system.

[0010] Further, the noble metal catalyst includes at least one of a platinum-based catalyst, a palladium-based catalyst, a ruthenium-based catalyst, and a rhodium-based catalyst.

[0011] Further, the noble metal catalyst includes a carrier material and a noble metal material supported on the carrier material, and the carrier material is selected from at least one of C, CeO 2 , Al 2 O 3 .

[0012] Further, the noble metal material is Pt, Pd, Ru, or Rh.

[0013] Further, the steps of the hydrogenation reaction include:

[0014] Mixing the liquid organic hydrogen storage material with the powdery lithium magnesium nitride hydride material to form a slurry;

[0015] Adding the noble metal catalyst to the slurry;

[0016] Heating the slurry and introducing hydrogen gas.

[0017] Further, the particle size of the lithium magnesium nitride hydride material is 10 nm to 10 μm.

[0018] Further, the dosage of the lithium magnesium nitride hydride material is 0.1 wt% to 10 wt% of the liquid organic hydrogen storage material.

[0019] Further, the preparation steps of the lithium magnesium nitride hydride material include:

[0020] Mixing LiNH 2 powder with MgH 2 powder, or mixing Mg(NH 2 ) 2 powder with LiH powder in a protective atmosphere to obtain a mixed powder;

[0021] Ball-milling the mixed powder for 12 h to 48 h in a protective atmosphere, with a ball-to-material ratio of 20:1 to 100:1 and a rotation speed of 150 rpm to 400 rpm, to obtain preliminary dehydrogenated particles;

[0022] Performing a dehydrogenation treatment on the preliminary dehydrogenated particles to obtain the lithium magnesium nitride hydride material.

[0023] The beneficial effects of the present invention are as follows: during the hydrogenation reaction of the liquid organic hydrogen storage material, the dehydrogenated lithium magnesium nitride hydride material can be used as a promoter for noble metal catalysts to activate hydrogen molecules, provide active hydrogen for the hydrogenation reaction, and through the synergistic reaction of the catalyst and the promoter, effectively improve the hydrogenation reaction rate of noble metal catalysts for organic liquid hydrogen storage materials, shorten the hydrogenation saturation time, reduce energy consumption, help reduce the usage amount of noble metals, and save costs.

[0024] Other features and advantages of the present application will be described in the subsequent specification, and part of them will become obvious from the specification or be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained by the written specification and the attached drawings. Description of the Drawings

[0025] Figure 1 It is the XRD pattern of the raw materials of Preparation Example 1, the nanosized lithium magnesium nitride hydride particles and the dehydrogenated lithium magnesium nitride hydride powder obtained in Preparation Example 1.

[0026] Figure 2 It is the comparison chart of the hydrogenation amount curves of Example 1 and Comparative Example 1.

[0027] Figure 3 It is the comparison chart of the hydrogenation amount curves of Example 2 and Comparative Example 2.

[0028] Figure 4 It is the comparison chart of the hydrogenation amount curves of Example 3 and Comparative Example 3.

[0029] Figure 5 It is the comparison chart of the fitting curve of Comparative Example 4 and Comparative Example 2, and the curves of Example 2, Comparative Example 4 and Comparative Example 2.

[0030] Figure 6 It is the comparison chart of the hydrogenation amount curves of Example 2, Example 4, Comparative Example 2, Comparative Example 5 and Comparative Example 6. Detailed Embodiments

[0031] To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0032] It should be understood that on the premise of no conflict, any and all implementation schemes of the present invention can be combined with the technical features in any other implementation scheme or multiple other implementation schemes to obtain additional implementation schemes. The present invention includes such additional implementation schemes obtained by combination.

[0033] In this specification, groups and their substituents can be selected by those skilled in the art to provide stable structural moieties and compounds. When a substituent is described by a conventional chemical formula written from left to right, the substituent also includes the chemically equivalent substituent obtained when the structural formula is written from right to left.

[0034] Unless otherwise specified, all technical and scientific terms used herein have the standard meanings in the field to which the claimed subject matter pertains. If there are multiple definitions for a term, the definition herein shall prevail.

[0035] Currently, there is still room for improvement in the hydrogenation kinetics of liquid organic hydrogen storage materials, and it is difficult to reduce the amount of noble metal catalysts used. Liquid organic hydrogen storage materials still mainly use noble metal-based catalysts for catalytic hydrogenation to meet application requirements. The catalysts are expensive, severely restricting the application and popularization of the LOHC technology.

[0036] The project team's experiments have confirmed that lithium magnesium nitride hydride materials can be used as co-catalysts for the hydrogenation reaction of liquid organic hydrogen storage materials. Among them, the main catalyst in the hydrogenation reaction is a noble metal catalyst. Lithium magnesium nitride hydride materials can not only be used as co-catalysts for the hydrogenation reaction of organic liquid hydrogen storage materials, but also have good hydrogen storage capacity, and can maintain a relatively high hydrogen storage density of the composite slurry as a whole.

[0037] Specifically, the liquid organic hydrogen storage material is selected from at least one of aromatic compounds and nitrogen-containing heterocyclic compounds. The aromatic compound is selected from at least one of benzene, toluene, dibenzyltoluene, naphthalene, and naphthalene derivatives. The nitrogen-containing heterocyclic compound is selected from at least one of carbazole, N-ethylcarbazole, N-propylcarbazole, indole, 1-methylindole, and 2-methylindole.

[0038] The noble metal catalyst includes a carrier material and a noble metal material supported on the carrier material. The carrier material is selected from at least one of carbon materials, cerium dioxide, and alumina.

[0039] The steps of the hydrogenation reaction include:

[0040] S1: Mix the liquid organic hydrogen storage material with the powdered lithium magnesium nitride hydride material to form a slurry.

[0041] S2: Add a noble metal catalyst to the slurry.

[0042] S3: Heat the slurry and introduce hydrogen gas.

[0043] Before introducing hydrogen gas in step S3, the gas in the reaction vessel can be replaced with nitrogen multiple times. The heating temperature in step S3 is the hydrogenation temperature when the liquid organic hydrogen storage material is catalyzed by a common noble metal catalyst.

[0044] The preparation steps of the lithium magnesium nitride hydride material include:

[0045] R1: Mix the LiNH 2 powder with the MgH 2 powder in a protective atmosphere, or mix the Mg(NH 2 ) 2 powder with the LiH powder to obtain a mixed powder.

[0046] R2: Ball-mill the mixed powder for 12 h to 48 h in a protective atmosphere, with a ball-to-powder ratio of 20:1 to 100:1 and a rotation speed of 150 rpm to 400 rpm to obtain preliminary dehydrogenated particles.

[0047] R3: Perform dehydrogenation treatment on the preliminary dehydrogenated particles to obtain a lithium-magnesium-nitrogen-hydrogen material.

[0048] In step R3, a hydrogen storage material performance tester or other dehydrogenation equipment can be used to perform more sufficient dehydrogenation on the nanosized lithium-magnesium-nitrogen-hydrogen powder.

[0049] Preparation Example 1

[0050] Mix the commercially available LiNH 2 powder and the commercially available MgH 2 powder in proportion in a glove box, and grind them using a planetary ball mill for 48 h, with a ball-to-powder ratio of 80:1 and a rotation speed of 300 rpm to obtain nanosized lithium-magnesium-nitrogen-hydrogen particles (the preliminary dehydrogenated particles mentioned in step R2). During this process, partial dehydrogenation occurs due to the externally applied mechanical energy. Then, use a hydrogen storage material performance tester (P-C-T) to perform more sufficient dehydrogenation on the nanosized lithium-magnesium-nitrogen-hydrogen particles at 200 °C to obtain a dehydrogenated lithium-magnesium-nitrogen-hydrogen (L-M-N-H) powder (the lithium-magnesium-nitrogen-hydrogen material mentioned in step R3).

[0051] The XRD results of the preliminary dehydrogenated particles (corresponding to the curve named "Ball-milled Li-Mg-N-H" in Figure 1 ), the lithium-magnesium-nitrogen-hydrogen material (corresponding to the curve named "200 °C dehydrogenated Li-Mg-N-H" in Figure 1 ), the commercially available LiNH 2 powder used as raw material, and the MgH 2 powder used as raw material are as shown in Figure 1 to confirm that the main phases of the preliminary dehydrogenated particles and the lithium-magnesium-nitrogen-hydrogen material are still LiNH 2 and MgH 2 .

[0052] Example 1: The dehydrogenated L-M-N-H forms a composite slurry with 1-methylindole and serves as a co-catalyst for Ru / Al 2 O 3 catalytic hydrogenation.

[0053] 10 g of 1-methylindole was premixed with the dehydrogenated lithium magnesium nitride hydrogen powder prepared in Preparation Example 1 to obtain a composite slurry with a mass fraction of dehydrogenated lithium magnesium nitride hydrogen powder of 3 wt%, which was added to a reaction kettle. At the same time, 2 g of Ru / Al 2 O 3 catalyst (ruthenium metal supported on alumina) was added. Then, the reaction kettle was evacuated and purged with hydrogen three times, and finally kept in a vacuum state.

[0054] The evacuated reaction kettle was heated to 145 °C, hydrogen with a pressure of 8 MPa was introduced, and stirring was maintained to carry out the hydrogenation reaction of 1-methylindole. The progress of the reaction was detected by the change in the pressure of the reaction kettle, and the results were corrected by GC-MS.

[0055] The results are as Figure 2 shown ( Figure 2 the curve named "hydrogenation after compounding with L-M-N-H" in 2 O 3 ). When 3 wt% of dehydrogenated L-M-N-H was used as a co-catalyst, the kinetic curve of the hydrogenation reaction of 1-methylindole catalyzed by Ru / Al

[0056] at 145 °C showed that the maximum addition value of the complex of L-M-N-H and 1-methylindole could reach 5.46 wt% in 270 min, and the hydrogenation amount reached 5.08 wt% in 210 min, which was 87.7% of the theoretical saturated hydrogenation amount (here, when L-M-N-H was compounded with LOHC, the hydrogenation amount was calculated based on the whole complex, and the same calculation method was used in the subsequent examples).

[0056] Comparative Example 1: Directly use Ru / Al 2 O 3 to catalyze the hydrogenation of 1-methylindole.

[0057] 10 g of 1-methylindole was added to a reaction kettle, and at the same time, 2 g of Ru / Al 2 O 3 catalyst was added. Then, the reaction kettle was evacuated and purged with hydrogen three times, and finally kept in a vacuum state.

[0058] The evacuated reaction kettle was heated to 145 °C, hydrogen with a pressure of 8 MPa was introduced, and stirring was maintained to carry out the hydrogenation reaction of 1-methylindole. The progress of the reaction was detected by the change in the pressure of the reaction kettle, and the results were corrected by GC-MS.

[0059] The results are as Figure 2 shown ( Figure 2 the curve named "hydrogenation of 1-methylindole" in 2 O 3The kinetic curve of the catalytic hydrogenation reaction of 1-methylindole shows that the maximum addition amount of 1-methylindole can reach 5.72 wt% in 390 min, and the hydrogenation amount reaches 2.89 wt% in 210 min, which is 49.9% of the theoretical saturated hydrogenation amount.

[0060] As can be seen from the comparison in Figure 2 after adding L-M-N-H as a co-catalyst, the hydrogenation rate is significantly accelerated, reaching the maximum hydrogenation amount faster. When hydrogenating to the same hydrogenation amount, Example 1 takes less time than Comparative Example 1.

[0061] Example 2: Dehydrogenated L-M-N-H and 1-methylindole form a composite slurry as a co-catalyst for Pd / Al 2 O 3 catalytic hydrogenation.

[0062] 10 g of 1-methylindole was pre-mixed with the dehydrogenated lithium magnesium nitride hydrogen powder prepared in Preparation Example 1 to obtain a composite slurry with a mass fraction of dehydrogenated lithium magnesium nitride hydrogen powder of 3 wt%, which was added to the reaction kettle. At the same time, 4 g of Pd / Al 2 O 3 catalyst was added, and then the reaction kettle was evacuated and purged with hydrogen three times, and finally kept in a vacuum state.

[0063] The evacuated reaction kettle was heated to 145 °C, hydrogen gas at 8 MPa was introduced, and stirring was maintained to carry out the hydrogenation reaction of 1-methylindole. The progress of the reaction was detected by the change in the pressure of the reaction kettle, and the results were corrected by GC-MS.

[0064] Comparative Example 2: Directly use Pd / Al 2 O 3 to catalyze the hydrogenation of 1-methylindole.

[0065] 10 g of 1-methylindole was added to the reaction kettle, and at the same time, 4 g of Pd / Al 2 O 3 catalyst was added, and then the reaction kettle was evacuated and purged with hydrogen three times, and finally kept in a vacuum state.

[0066] The evacuated reaction kettle was heated to 145 °C, hydrogen gas at 8 MPa was introduced, and stirring was maintained to carry out the hydrogenation reaction of 1-methylindole. The progress of the reaction was detected by the change in the pressure of the reaction kettle, and the results were corrected by GC-MS.

[0067] As Figure 3 shown, comparing Example 2 ( Figure 3 the curve named "hydrogenation after compounding with L-M-N-H" in Figure 3Results of the curve named "1-methylindole hydrogenation" in the figure), when 3 wt% dehydrogenated L-M-N-H is used as a cocatalyst, Pd / Al at 145 °C 2 O 3 The kinetic curve of the catalytic hydrogenation of 1-methylindole shows that the maximum addition value of 1-methylindole can reach 5.39 wt% in 240 min, and the hydrogenation amount reaches 5.23 wt% in 180 min, which is 90.3% of the theoretical saturated hydrogenation amount. Without using dehydrogenated L-M-N-H as a cocatalyst, Pd / Al at 145 °C 2 O 3 The kinetic curve of the catalytic hydrogenation of 1-methylindole shows that the maximum addition value of 1-methylindole can reach 5.79 wt% in 660 min, and the hydrogenation amount reaches 2.51 wt% in 180 min, which is 43.4% of the theoretical saturated hydrogenation amount.

[0068] Figure 3 The comparison in the figure also confirms that after adding L-M-N-H as a cocatalyst, the hydrogenation rate is significantly accelerated, reaching the maximum hydrogenation amount faster, and when hydrogenating to the same hydrogenation amount, Example 2 takes less time than Comparative Example 2.

[0069] Example 3: Dehydrogenated L-M-N-H and N-ethylcarbazole form a composite slurry as a cocatalyst for Pd / Al 2 O 3 catalytic hydrogenation.

[0070] Pre-mix 10 g of N-ethylcarbazole with the dehydrogenated lithium magnesium nitride hydride powder prepared in Preparation Example 1 to obtain a composite slurry with a mass fraction of dehydrogenated lithium magnesium nitride hydride powder of 3 wt%, add it to the reaction kettle, and at the same time add 4 g of Pd / Al 2 O 3 catalyst, then evacuate and hydrogenate the reaction kettle 3 times, and finally keep it in a vacuum state.

[0071] Heat the evacuated reaction kettle to 180 °C, introduce 8 MPa of hydrogen, keep stirring, carry out the hydrogenation reaction of N-ethylcarbazole, detect the progress of the reaction through the pressure change of the reaction kettle, and correct the results by GC-MS.

[0072] Comparative Example 3: Directly use Pd / Al 2 O 3 to catalyze the hydrogenation of N-ethylcarbazole.

[0073] Add 10 g of N-ethylcarbazole to the reaction kettle, and at the same time add 4 g of Pd / Al 2 O 3 catalyst, then evacuate and hydrogenate the reaction kettle 3 times, and finally keep it in a vacuum state.

[0074] The evacuated autoclave was heated to 180 °C, hydrogen gas at 8 MPa was introduced, stirring was maintained, and the hydrogenation reaction of N-ethylcarbazole was carried out. The progress of the reaction was detected by the change in the pressure of the autoclave, and the results were corrected by GC-MS.

[0075] As Figure 4 shown, comparing the results of Example 3 ( Figure 4 the curve named "hydrogenation after compounding with L-M-N-H" in Figure 4 ) and Comparative Example 3 ( 2 O 3 the curve named "N-ethylcarbazole" in 2 O 3 ), when 3 wt% dehydrogenated L-M-N-H was used as a cocatalyst, the kinetic curve of the hydrogenation reaction of N-ethylcarbazole catalyzed by Pd / Al

[0076] at 180 °C showed that the maximum addition value of N-ethylcarbazole could reach 5.57 wt% in 420 min, and the hydrogenation amount reached 5.01 wt% in 300 min, which was 86.5% of the theoretical saturated hydrogenation amount. Without using dehydrogenated L-M-N-H as a cocatalyst, the kinetic curve of the hydrogenation reaction of N-ethylcarbazole catalyzed by Pd / Al 2 O 3 at 180 °C showed that the maximum addition value of N-ethylcarbazole could reach 5.54 wt%, and the hydrogenation amount reached 4.42 wt% in 300 min, which was 76.3% of the theoretical saturated hydrogenation amount.

[0077] Comparative Example 4: A composite slurry of dehydrogenated L-M-N-H and n-hexane (n-hexane is an inert solvent, and prior art has proven its lack of hydrogen absorption ability) was formed, and the Pd / Al 2 O 3 catalyst was used to test the hydrogenation curve of dehydrogenated L-M-N-H itself.

[0078] 10 g of n-hexane was pre-mixed with the dehydrogenated lithium magnesium nitride hydrogen powder prepared in Preparation Example 1 with a mass fraction of 3 wt% based on n-hexane, added to the autoclave, and at the same time 4 g of Pd / Al 2 O 3 catalyst was added. Then, the autoclave was evacuated and hydrogen gas was introduced, and this was repeated 3 times. Finally, the vacuum state was maintained.

[0078] The evacuated autoclave was heated to 145 °C, hydrogen gas at 8 MPa was introduced, stirring was maintained, and the hydrogenation reaction of dehydrogenated L-M-N-H was carried out. The progress of the reaction was detected by the change in the pressure of the autoclave.

[0079] The results were as Figure 5 shown. In a dispersion state similar to that of the composite slurry in Example 2, the Pd / Al 2 O 3The kinetic curve of the dehydrogenation of 3 wt% L-M-N-H hydrogenation shows that ( Figure 5 the curve named "Self-hydrogenation of dehydrogenated L-M-N-H" in

[0080] ), its addition amount reaches 2.41 wt% at 480 min and tends to be stable. Figure 5 The ordinate of the hydrogenation amount curve of Comparative Example 4 is multiplied by 3 wt% and added to the ordinate of the hydrogenation amount curve of Comparative Example 2 multiplied by 97 wt% to obtain the ordinate of the fitted hydrogenation curve. This curve (

[0081] Comparison Figure 5 It can be seen that whether it is compared with the hydrogenation curve of a single dehydrogenated L-M-N-H (Comparative Example 2, Figure 5 the curve named "Hydrogenation of 1-methylindole" in Figure 5 the curve named "Self-hydrogenation of dehydrogenated L-M-N-H" in Figure 5 ), or compared with the fitted hydrogenation curve of the combination of the two, the actual hydrogenation curve (Example 2,

[0082] Example 4: The preliminary dehydrogenated particles and 1-methylindole form a composite slurry as a co-catalyst for Pd / Al 2 O 3 catalytic hydrogenation.

[0083] 10 g of 1-methylindole is pre-mixed with the nanosized lithium magnesium nitride hydrogen particles prepared in Preparation Example 1 to obtain a composite slurry with a mass fraction of nanosized lithium magnesium nitride hydrogen particles of 3 wt%. It is added to the reaction kettle, and at the same time, 4 g of Pd / Al 2 O 3 catalyst is added. Then, the reaction kettle is evacuated and hydrogen is introduced, and this is repeated 3 times. Finally, it is kept in a vacuum state.

[0084] The evacuated reaction kettle is heated to 145 °C, hydrogen with a pressure of 8 MPa is introduced, stirring is maintained, and hydrogenation reaction of 1-methylindole is carried out. The progress of the reaction is detected by the pressure change of the reaction kettle, and the results are corrected by GC-MS.

[0085] Comparative Example 5: Commercial LiNH 2 forms a composite slurry with 1-methylindole, and then Pd / Al 2 O 3 is used as the main catalyst.

[0086] 10 g of 1-methylindole was premixed with the commercial LiNH of the raw materials in Preparation Example 1 2 to obtain a composite slurry with a mass fraction of 3 wt% of commercial LiNH 2 which was added to a reaction kettle. Meanwhile, 4 g of Pd / Al 2 O 3 catalyst was added. Then, the reaction kettle was evacuated and purged with hydrogen three times, and finally kept in a vacuum state.

[0087] The evacuated reaction kettle was heated to 145 °C, hydrogen gas at 8 MPa was introduced, and stirring was maintained to carry out the hydrogenation reaction of 1-methylindole. The progress of the reaction was detected by the change in the pressure of the reaction kettle, and the results were corrected by GC-MS.

[0088] Comparative Example 6: Commercial MgH 2 formed a composite slurry with 1-methylindole, and then Pd / Al 2 O 3 was used as the main catalyst.

[0089] 10 g of 1-methylindole was premixed with the commercial MgH of the raw materials in Preparation Example 1 2 to obtain a composite slurry with a mass fraction of 3 wt% of commercial LiNH 2 which was added to a reaction kettle. Meanwhile, 4 g of Pd / Al 2 O 3 catalyst was added. Then, the reaction kettle was evacuated and purged with hydrogen three times, and finally kept in a vacuum state.

[0090] The evacuated reaction kettle was heated to 145 °C, hydrogen gas at 8 MPa was introduced, and stirring was maintained to carry out the hydrogenation reaction of 1-methylindole. The progress of the reaction was detected by the change in the pressure of the reaction kettle, and the results were corrected by GC-MS.

[0091] The results of Example 4, Comparative Example 5, and Comparative Example 6 are as Figure 6 shown.

[0092] In Example 2, 3 wt% dehydrogenated L-M-N-H was used as a co-catalyst. The kinetic curve of the hydrogenation reaction of 1-methylindole catalyzed by Pd / Al 2 O 3 at 145 °C showed that the maximum addition value of 1-methylindole could reach 5.39 wt% in 240 min, and the hydrogenation amount reached 5.23 wt% in 180 min, which was 90.3% of the theoretical saturated hydrogenation amount.

[0093] In Example 4, 3 wt% of the ball-milled nanosized L-M-N-H powder was used as a co-catalyst. At 145 °C, Pd / Al2 O 3 The kinetic curve of the catalytic hydrogenation reaction of 1-methylindole shows that the maximum addition value of 1-methylindole can reach 5.18 wt% in 600 min, and the hydrogenation amount reaches 4.38 wt% in 180 min, which is 75.6% of the theoretical saturated hydrogenation amount.

[0094] In Comparative Example 5, 3 wt% of commercial LiNH 2 was used as a composite additive, and Pd / Al 2 O 3 The kinetic curve of the catalytic hydrogenation reaction of 1-methylindole shows that the maximum addition value of 1-methylindole can reach 4.80 wt% in 500 min, and the hydrogenation amount reaches 2.55 wt% in 180 min, which is 44.0% of the theoretical saturated hydrogenation amount.

[0095] In Comparative Example 6, 3 wt% of commercial MgH 2 was used as a composite additive, and Pd / Al 2 O 3 The kinetic curve of the catalytic hydrogenation reaction of 1-methylindole shows that the maximum addition value of 1-methylindole can reach 5.33 wt% in 720 min, and the hydrogenation amount reaches 2.05 wt% in 180 min, which is 35.4% of the theoretical saturated hydrogenation amount.

[0096] In Comparative Example 2, L-M-N-H was not used as a cocatalyst, and Pd / Al 2 O 3 The kinetic curve of the catalytic hydrogenation reaction of 1-methylindole shows that the maximum addition value of 1-methylindole can reach 5.79 wt% in 660 min, and the hydrogenation amount reaches 2.51 wt% in 180 min, which is 43.4% of the theoretical saturated hydrogenation amount.

[0097] This comparison result shows that ball-milled L-M-N-H has a cocatalytic effect, and after dehydrogenation treatment, the cocatalytic rate and the final hydrogenation capacity can be further improved. However, when using commercial LiNH 2 or commercial MgH 2 alone, there is no such effect. The above comparison proves that the nanostructured lithium-magnesium-nitrogen-hydrogen powder has unique cocatalytic characteristics, and this cocatalytic effect may be positively correlated with the ability of each additive to provide active hydrogen (i.e., inversely proportional to the dehydrogenation degree of each additive). A similar rule can also be observed from the comparison of the maximum hydrogenation amounts of composite slurries containing various additives.

[0098] In the description of this specification, the descriptions with reference to the terms "one embodiment", "certain embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0099] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. Application of lithium magnesium nitrogen hydrogen material, characterized in that: As a co-catalyst in the hydrogenation reaction of the liquid organic hydrogen storage material, the main catalyst in the hydrogenation reaction is a precious metal catalyst; The liquid organic hydrogen storage material is selected from at least one of an aromatic compound and a nitrogen-containing heterocyclic compound; The steps of preparing the lithium magnesium nitrogen hydrogen material include: Mixing LiNH2 powder and MgH2 powder, or mixing Mg(NH2)2 powder and LiH powder in a protective atmosphere to obtain a mixed powder; Ball milling the mixed powder for 12 h to 48 h under a protective atmosphere, with a ball-to-powder ratio of 20:1 to 100:1 and a rotation speed of 150 rpm to 400 rpm, to obtain preliminary dehydrogenated particles; The preliminary dehydrogenated particles are subjected to a dehydrogenation treatment to obtain the lithium magnesium nitrogen hydrogen material.

2. The use of the lithium magnesium nitrogen hydrogen material according to claim 1, characterized in that: The aromatic compound is selected from at least one of benzene, toluene, dibenzyltoluene, naphthalene and naphthalene derivatives.

3. The use of the lithium magnesium nitrogen hydrogen material according to claim 1, characterized in that: The nitrogen-containing heterocyclic compound is at least one selected from carbazole, N-ethylcarbazole, N-propylcarbazole, indole, 1-methylindole, and 2-methylindole.

4. The use of the lithium magnesium nitrogen hydrogen material according to claim 1, characterized in that: The noble metal catalyst includes at least one of a platinum-based catalyst, a palladium-based catalyst, a ruthenium-based catalyst, and a rhodium-based catalyst.

5. The use of the lithium magnesium nitrogen hydrogen material according to claim 1, characterized in that: The noble metal catalyst comprises a carrier material and a noble metal material loaded on the carrier material, and the carrier material is selected from at least one of C, CeO2, and Al2O3.

6. The use of the lithium magnesium nitrogen hydrogen material according to claim 1, characterized in that: The steps of the hydrogenation reaction include: Mixing the liquid organic hydrogen storage material and the powdered lithium magnesium nitrogen hydrogen material into a slurry; adding the noble metal catalyst to the slurry; The slurry was heated and hydrogen was passed through.

7. The use of the lithium magnesium nitrogen hydrogen material according to claim 6, characterized in that: The particle size of the lithium magnesium nitrogen hydrogen material is 10nm~10μm.

8. The use of the lithium magnesium nitrogen hydrogen material according to claim 1, characterized in that: The amount of the lithium magnesium nitrogen hydrogen material is 0.1 wt% to 10 wt% of the liquid organic hydrogen storage material.

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