A TiO2-based catalyst, its preparation method and application

Abstract

The present invention provides a TiO2-based catalyst, a preparation method thereof and an application. The TiO2-based catalyst is prepared by subjecting TiO2 to a reduction reaction with an alkali metal compound containing a nitrogen atom and / or an alkaline earth metal compound containing a nitrogen atom. By subjecting TiO2 to a reduction reaction with an alkali metal compound containing a nitrogen atom and / or an alkaline earth metal compound, a part of titanium dioxide is reduced to titanate, and a titanate composite doped with an alkali metal / alkaline earth metal and a nitrogen anion, namely, the TiO2-based catalyst, is obtained. Through research, the magnesium-based hydrogen storage material compounded with the TiO2-based catalyst has a lower hydrogen absorption and desorption temperature, and the hydrogen absorption and desorption kinetic performance is significantly improved, and it also has good cycle stability. At the same time, the raw material cost of the TiO2-based catalyst is low, and the preparation process is simple and easy to implement, which is suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen storage materials, and particularly relates to a TiO2-based catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous progress and development of human society, the energy crisis caused by the large consumption of fossil fuels such as coal, oil, and natural gas and the resulting environmental problems are the most severe challenges currently faced by mankind. Therefore, the development of clean energy has become a topic of common concern worldwide. As a clean energy with rich reserves, clean and pollution-free, high mass energy density, and diverse utilization forms, in the foreseeable future, its large-scale application will have a significant impact on the development of human society. However, the efficient and safe storage of hydrogen has always been the main technical bottleneck restricting the development of hydrogen energy.

[0003] Since the proposal of metal-based hydrogen storage materials, they have always been the focus and key points of research in the energy field. Among them, magnesium-based metal hydrides represented by MgH2, because Mg is an element with rich reserves (the content of Mg in the earth's crust is about 2.5 wt%), has a high mass hydrogen storage density (7.6 wt%), a volume hydrogen storage density (110 kg / m 3 ) and the advantages of low raw material prices, etc., and is considered to be one of the most promising hydrogen storage materials. However, due to the relatively strong chemical bond between Mg metal and hydrogen, the thermal stability of Mg metal hydride is relatively high, and its hydrogen absorption and desorption thermodynamics and kinetics are poor. The hydrogen absorption and dehydrogenation operation temperature of pure magnesium hydride is higher than 350 °C, and the temperature for releasing 0.1 MPa equilibrium hydrogen pressure is higher than 300 °C, which seriously hinders its further application.

[0004] Currently, adding a catalyst to magnesium-based metal hydrides is one of the effective methods to improve the hydrogen absorption and desorption performance of magnesium-based hydrogen storage materials. Currently, the catalysts with better catalytic effects mainly include transition metals and their oxides, such as Ti-based material TiO2. Some studies have shown that in the system of TiO2-doped magnesium-based metal hydrides, the dehydrogenation rate exceeds 20 kW / kg, and the dehydrogenation activation energy of the material can be reduced. However, although adding TiO2 can improve the hydrogen absorption and desorption performance of magnesium-based metal hydrides to a certain extent, the hydrogen absorption and desorption temperature is still higher than 300 °C, and the cycle stability is poor, which still has a certain gap from the actual application requirements of magnesium-based hydrogen storage materials. Therefore, further developing highly efficient catalysts with low cost and reducing the working temperature of magnesium-based hydrogen storage materials for hydrogen absorption and desorption have important practical significance and value for promoting the actual application of hydrogen storage materials. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a TiO2-based catalyst, a preparation method thereof and an application. The TiO2-based catalyst is obtained by reacting a nitrogen-containing alkali metal compound and / or an alkaline earth metal compound with TiO2, and the obtained catalyst is compounded with a magnesium-based hydrogen storage material, which can reduce the working temperature of the magnesium-based hydrogen storage material for hydrogen absorption and desorption and has good cycle stability.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a TiO2-based catalyst, which is prepared by subjecting TiO2 to a reduction reaction with a nitrogen-containing alkali metal compound and / or a nitrogen-containing alkaline earth metal compound.

[0008] Preferably, the nitrogen-containing alkali metal compound is selected from any one or more of alkali metal nitrides, amino compounds or imino compounds.

[0009] Preferably, the nitrogen-containing alkaline earth metal compound is selected from any one or more of alkaline earth metal nitrides, amino compounds or imino compounds.

[0010] Preferably, the mass ratio of the nitrogen-containing alkali metal compound and / or the nitrogen-containing alkaline earth metal compound to TiO2 is 1:(0.5-10).

[0011] Preferably, the configuration of the TiO2 is a rutile structure and / or anatase structure.

[0012] In the second aspect, the present invention provides a preparation method of the above TiO2-based catalyst, which includes the following steps:

[0013] React TiO2 with a nitrogen-containing alkali metal compound and / or a nitrogen-containing alkaline earth metal compound in a protective atmosphere or a vacuum environment by any one of ball milling, calcination or stirring to obtain the TiO2-based catalyst.

[0014] Preferably, the pressure of the ball milling is 0.1-1 MPa, the temperature is 10-100 °C, the rotation speed is 50-600 rpm, and the ball-to-material ratio is (20-120):1.

[0015] Preferably, the pressure of the stirring is 0.1-10 MPa, the temperature is 10-100 °C, the time is 1-40 h, and the stirring rate is 500-30000 rpm.

[0016] Preferably, the pressure of the calcination is 0.01-10 bar, the temperature is 200-800 °C, the time is 1-20 h, and the heating rate is 1-10 °C / min.

[0017] Thirdly, the present invention provides the application of the TiO2-based catalyst involved in the above technical solution in the hydrogen storage reaction.

[0018] Fourthly, the present invention provides a magnesium-based hydrogen storage material, which includes a catalyst and a magnesium-based material.

[0019] The catalyst is the TiO2-based catalyst involved in the above technical solution.

[0020] Preferably, the magnesium-based material is selected from any one or more of MgH2, magnesium powder, magnesium-based alloy hydride or magnesium-based alloy.

[0021] Preferably, the mass ratio of the catalyst to the magnesium-based material is (5-10):(90-95).

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The present invention provides a TiO2-based catalyst for magnesium-based hydrogen storage materials. The TiO2-based catalyst undergoes a reduction reaction with an alkali metal compound and / or an alkaline earth metal compound containing a nitrogen atom to reduce part of the titanium dioxide to titanate, obtaining an alkali metal / alkaline earth metal, nitrogen anion-doped titanate composite. Through research, the introduction of N anions can significantly narrow the band gap of the titanate, making the outermost electrons more easily excited into free electrons. Through research, the magnesium-based hydrogen storage material compounded with the TiO2-based catalyst has lower hydrogen absorption and desorption temperatures (below 300 °C), and the hydrogen absorption and desorption kinetic performance is significantly improved. Initial hydrogen absorption and desorption do not require activation, not only maintaining a fast hydrogen absorption and desorption speed but also having good cycle stability (it can operate stably for more than 800 h). At the same time, the raw material cost of the TiO2-based catalyst is low, and the preparation process is simple and easy to implement, suitable for large-scale production. Description of the Drawings

[0024] Figure 1 It is the temperature-programmed dehydrogenation curve of the MgH2 hydrogen storage material in Example 1;

[0025] Figure 2 It is the XRD pattern of the MgH2 hydrogen storage material in Example 1;

[0026] Figure 3 It is the temperature-programmed dehydrogenation curve of the MgH2 hydrogen storage material in Example 2;

[0027] Figure 4 It is the XRD pattern of the MgH2 hydrogen storage material in Example 2;

[0028] Figure 5 It is the XRD pattern of the MgH2 hydrogen storage material in Example 3;

[0029] Figure 6 It is the temperature-programmed dehydrogenation curve of the MgH2 hydrogen storage material in Example 4;

[0030] Figure 7 It is the temperature-programmed dehydrogenation mass spectrometry curve of the MgH2 hydrogen storage material in Example 5;

[0031] Figure 8 It is the SEM image of the MgH2 hydrogen storage material in Example 5;

[0032] Figure 9 It is the temperature-programmed dehydrogenation mass spectrometry curve of the MgH2 hydrogen storage material in Example 6;

[0033] Figure 10 It is the temperature-programmed dehydrogenation mass spectrometry curve of the MgH2 hydrogen storage material in Comparative Example 1;

[0034] Figure 11 It is the temperature-programmed dehydrogenation curve of the MgH2 hydrogen storage material in Comparative Example 1;

[0035] Figure 12 It is the cycle performance graph of the MgH2 hydrogen storage material in Example 1. Detailed implementation manners

[0036] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] In view of the problems that the system of TiO2-doped magnesium-based metal hydrides in the prior art still has high hydrogen absorption and desorption temperatures and poor cycle stability, the present invention provides a TiO2-based catalyst, which is prepared by subjecting TiO2 to a reduction reaction with an alkali metal compound containing a nitrogen atom and / or an alkaline earth metal compound containing a nitrogen atom. Among them, TiO2 can be a general commercially available product, and its configuration can be a rutile structure and / or anatase structure. The alkali metal compound containing a nitrogen atom is selected from any one or more of nitrides, amino compounds or imino compounds of alkali metals, and the alkali metal is selected from any one or more of Li, Na, K or Rb. The alkaline earth metal compound containing a nitrogen atom is selected from any one or more of nitrides, amino compounds or imino compounds of alkaline earth metals, and the alkaline earth metal is selected from any one or more of Mg, Ca, Ba or Sr. In some embodiments of the present invention, the mass ratio of the alkali metal compound containing a nitrogen atom and / or the alkaline earth metal compound containing a nitrogen atom to TiO2 is preferably 1:(0.5-10), such as 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, etc. The remaining ratios within the range are also within the protection scope of the present invention and will not be elaborated one by one here.

[0038] The TiO2-based catalyst provided by the present invention, through the reduction reaction of TiO2 with an alkali metal compound containing a nitrogen atom and / or an alkaline earth metal compound, reduces part of the titanium dioxide to titanate, and obtains an alkali metal / alkaline earth metal, nitrogen anion-doped titanate composite. Through research, the introduction of nitrogen anions can significantly narrow the band gap of titanate, making the outermost electrons easier to be excited into free electrons. At the same time, alkali metals and alkaline earth metals are abundant in the earth's crust, easy to obtain and low in cost. Applying the above low-cost TiO2-based catalyst in the field of magnesium-based hydrogen storage materials helps to realize the hydrogen absorption and desorption behavior of magnesium-based hydrogen storage materials at a lower working temperature.

[0039] The TiO2-based catalyst can be obtained by subjecting TiO2 and an alkali metal compound and / or an alkaline earth metal compound containing nitrogen atoms to a reduction reaction in a protective atmosphere or in vacuo by any one of ball milling, calcination or stirring. The protective atmosphere can be an inert gas, hydrogen or nitrogen. The inert atmosphere is an atmosphere well-known to those skilled in the art. In some embodiments of the present invention, argon and / or helium are preferred, and argon is more preferred. In some embodiments of the present invention, it is preferred to mix TiO2 and an alkali metal compound and / or an alkaline earth metal compound containing nitrogen atoms in a mass ratio of 1:(0.5-10) in a protective atmosphere of 0.1-10 MPa, and ball mill and compound them for 1-40 h at 10-100 °C and 50-600 rpm. More preferably, ball mill and compound them for 10-20 h at 30-50 °C and 100-400 rpm to obtain the TiO2-based catalyst. Among them, the ball-to-material ratio of the ball milling is preferably (20-120):1, and more preferably 30-100:1. In some embodiments of the present invention, it is preferred to mix TiO2 and an alkali metal compound and / or an alkaline earth metal compound containing nitrogen atoms in a mass ratio of 1:(0.5-10) in a protective atmosphere of 0.1-10 MPa, and stir them for 1-40 h at 10-100 °C and 500-30000 rpm. More preferably, stir them for 5-20 h at 20-30 °C and 500-2000 rpm to obtain the TiO2-based catalyst. In some embodiments of the present invention, it is preferred to mix TiO2 and an alkali metal compound and / or an alkaline earth metal compound containing nitrogen atoms in a mass ratio of 1:(0.5-10) in a protective atmosphere of 0.01-10 bar, heat them to 200-800 °C at a rate of 1-10 °C / min and then calcine them for 1-20 h. More preferably, heat them to 350-600 °C at a rate of 2-6 °C / min and then calcine them for 3-18 h to obtain the TiO2-based catalyst.

[0040] The preparation method of the above TiO2-based catalyst is simple and easy to implement, and is suitable for large-scale production.

[0041] The above TiO₂-based catalyst can be applied to hydrogen storage reactions. In some embodiments of the present invention, the above TiO₂-based catalyst can be compounded with a magnesium-based material in a protective atmosphere or a vacuum environment to obtain a magnesium-based hydrogen storage material. Among them, the magnesium-based material is selected from any one or more of MgH₂, magnesium powder, magnesium-based alloy hydrides or magnesium-based alloys. The protective atmosphere can be an inert gas, hydrogen or nitrogen, and the inert atmosphere is an atmosphere well-known to those skilled in the art. In some embodiments of the present invention, argon and / or helium are preferred, and argon is more preferred. In some embodiments of the present invention, the mass ratio of the TiO₂-based catalyst to the magnesium-based material is (5-10):(90-95), such as 5:95, 6:94, 7:93, 8:92, 9:91 or 10:90, etc. The remaining ratios within the range are also within the protection scope of the present invention and will not be elaborated one by one here.

[0042] In the present invention, the TiO₂-based catalyst is compounded with the magnesium-based material. Through research, the obtained magnesium-based hydrogen storage material has lower hydrogen absorption and desorption temperatures, and the hydrogen absorption and desorption kinetic performance is significantly improved. Initial hydrogen absorption and desorption do not require activation, not only maintaining a fast hydrogen absorption and desorption speed, but also having good cycle stability.

[0043] In some embodiments of the present invention, the magnesium-based hydrogen storage material can be mechanically mixed and compounded by a TiO₂-based catalyst and a magnesium-based material in a protective atmosphere or a vacuum environment, and the mechanical mixing includes ball milling or stirring. In some embodiments of the present invention, preferably in a protective atmosphere of 0.1-10 MPa, the TiO₂-based catalyst and the magnesium-based material are mixed in a mass ratio of (5-10):(90-95), and ball milled and mixed for 1-60 h under the conditions of 10-100 °C and 50-600 rpm. More preferably, it is ball milled and mixed for 10-30 h under the conditions of 10-100 °C and 100-400 rpm to obtain the magnesium-based hydrogen storage material. Among them, the ball-to-material ratio of the ball milling is preferably (10-150):1, more preferably (40-80):1, and most preferably 40:1. In some embodiments of the present invention, preferably in a protective atmosphere of 0.1-10 MPa, the TiO₂-based catalyst and the magnesium-based material are mixed in a mass ratio of (5-10):(90-95), and stirred for 1-40 h under the conditions of 10-100 °C and 2000-10000 rpm to obtain the magnesium-based hydrogen storage material.

[0044] The preparation method of the above-mentioned magnesium-based hydrogen storage material is simple and easy to implement. Through mechanical mixing, the catalyst and the magnesium-based material can be more closely and evenly contacted, which helps to improve the catalytic effect. At the same time, the grain size of the magnesium-based material can be significantly reduced during the mechanical mixing process, so that the absorption / desorption kinetics of the magnesium-based hydrogen storage material is significantly improved. Moreover, the preparation method does not require expensive instruments or equipment, is easy to implement, and is suitable for large-scale production.

[0045] Through XRD characterization of the prepared magnesium-based hydrogen storage material of the present invention, it is found that the magnesium-based main body in the magnesium-based hydrogen storage material is not significantly oxidized due to the addition of the TiO2-based catalyst. Through the HPSA-auto instrument for hydrogen absorption and dehydrogenation analysis of the magnesium-based hydrogen storage material, it is found that the addition of the TiO2-based catalyst can significantly reduce the initial dehydrogenation temperature (below 250 °C) and the peak dehydrogenation temperature (below 300 °C) of the magnesium-based hydrogen storage material, significantly improve the kinetic performance of dehydrogenation of the magnesium-based hydrogen storage material, and the magnesium-based hydrogen storage material has a high hydrogen storage capacity. In addition, for the obtained magnesium-based hydrogen storage material, cyclic tests of hydrogen absorption and dehydrogenation are carried out, and it is found that it has good cyclic stability and can operate stably for more than 800 h.

[0046] To further illustrate the present invention, the following examples are used for detailed description. The experimental raw materials used in the following examples of the present invention can be purchased from the market or prepared according to the conventional preparation methods well-known to those skilled in the art.

[0047] Example 1

[0048] This example provides a MgH2 hydrogen storage material, and the preparation method is as follows:

[0049] In an argon-protected glove box, 3 g of sodium amide particles and TiO2 (rutile type) were weighed respectively at a mass ratio of 1:1, mixed and loaded into a ball mill jar. According to a ball-to-material ratio of 30:1, in an argon atmosphere of 0.1 MPa and at 30 °C, ball milling was carried out for 10 h at a rotation speed of 100 rpm to obtain a TiO2-based catalyst;

[0050] In an argon-protected glove box, 2 g of a mixture of a TiO2-based catalyst and MgH2 was weighed at a mass ratio of 5:95 and loaded into a ball mill jar. According to a ball-to-material ratio of 40:1, under an argon atmosphere of 0.1 MPa at room temperature, ball milling was carried out for 12 h at a rotation speed of 200 rpm to obtain a MgH2 hydrogen storage material.

[0051] The HPSA-auto instrument was used to conduct hydrogen absorption and dehydrogenation analysis tests on the MgH2 hydrogen storage material, and the test method was as follows:

[0052] In the glove box, weigh 150 mg of the MgH2 hydrogen storage material obtained in Example 1 and load it into the pressure-resistant reactor provided in the instrument. Use a temperature controller to heat the reactor from room temperature to 400°C at a heating rate of 2°C / min, and record the curve of the dehydrogenation amount changing with time and temperature. The dehydrogenation amount is automatically converted by the instrument according to the change in the gas volume of the system.

[0053] Test results such as Figure 1 As shown, Figure 1 The temperature-programmed dehydrogenation curve of the MgH2 hydrogen storage material shows that the initial and peak dehydrogenation temperatures of the MgH2 hydrogen storage material composited with the TiO2-based catalyst are both low, wherein the initial dehydrogenation temperature is lower than 250° C. and the peak dehydrogenation temperature is lower than 300° C. In addition, it is calculated that the MgH2 hydrogen storage material has a high hydrogen storage capacity of 7.15wt%.

[0054] The MgH2 hydrogen storage material was characterized by X'Pert3 X-ray powder crystal diffractometer, and the obtained XRD pattern is as follows: Figure 2 As shown, it can be seen that the MgH2 hydrogen storage material composited with the TiO2-based catalyst does not show significant oxidation due to the addition of the TiO2-based catalyst.

[0055] Example 2

[0056] This embodiment provides a MgH2 hydrogen storage material, and the preparation method is as follows:

[0057] In an argon-protected glove box, potassium amide particles and TiO2 (rutile type) were weighed in a mass ratio of 1:3, 3 grams in total, mixed and loaded into a ball mill, and the ball-to-material ratio was 30:1. In a 0.1 MPa argon atmosphere, at 40°C, the ball milling was performed for 10 hours at a speed of 100 rpm to obtain a TiO2-based catalyst;

[0058] In an argon-protected glove box, a mixture of TiO2-based catalyst and MgH2 in a mass ratio of 5:95 was weighed and loaded into a ball mill with a ball-to-material ratio of 40:1. The mixture was ball-milled for 15 h at a speed of 150 rpm at room temperature and 0.1 MPa argon atmosphere to obtain MgH2 hydrogen storage material.

[0059] Referring to Example 1, the MgH2 hydrogen storage material was subjected to absorption and dehydrogenation analysis tests. The temperature-programmed dehydrogenation curve of the MgH2 hydrogen storage material is shown in FIG. Figure 3 As shown, it can be seen that the initial and peak dehydrogenation temperatures of the MgH2 hydrogen storage material composited with the TiO2-based catalyst are both low, wherein the initial dehydrogenation temperature is lower than 250° C. and the peak dehydrogenation temperature is lower than 300° C. In addition, it is calculated that the MgH2 hydrogen storage material has a high hydrogen storage capacity of 7.17 wt%.

[0060] The MgH2 hydrogen storage material was characterized by an X'Pert3 X-ray powder diffractometer, and the obtained XRD pattern is as Figure 4 shown. It can be seen that the MgH2 hydrogen storage material composite with the TiO2-based catalyst did not show significant oxidation due to the addition of the TiO2-based catalyst.

[0061] Example 3

[0062] This example provides a MgH2 hydrogen storage material, and the preparation method is as follows:

[0063] In an argon-protected glove box, 3 g of sodium nitride particles and TiO2 (rutile type) were weighed respectively at a mass ratio of 1:3, mixed and loaded into a reaction tube. In an argon atmosphere of 0.1 MPa, it was heated to 500 °C at a rate of 2 °C / min and calcined at 500 °C for 5 h to obtain a TiO2-based catalyst;

[0064] In an argon-protected glove box, 2 g of a mixture of the TiO2-based catalyst and MgH2 were weighed at a mass ratio of 5:95 and loaded into a ball mill tank. According to a ball-to-material ratio of 40:1, it was ball milled for 10 h at room temperature in an argon atmosphere of 0.1 MPa with a rotation speed of 150 rpm to obtain a MgH2 hydrogen storage material.

[0065] The MgH2 hydrogen storage material was characterized by an X'Pert3 X-ray powder diffractometer, and the obtained XRD pattern is as Figure 5 shown. It can be seen that the half-peak width of the diffraction peak of the MgH2 hydrogen storage material is relatively wide, indicating that its grain size is small. In addition, a weak diffraction peak belonging to MgO can also be observed, indicating that during the ball milling process, the TiO2-based catalyst reacted with MgH2 and was further reduced.

[0066] Example 4

[0067] This example provides a MgH2 hydrogen storage material, and the preparation method is as follows:

[0068] In an argon-protected glove box, 3 g of calcium nitride particles and TiO2 (anatase type) were weighed respectively at a mass ratio of 1:3, mixed and loaded into a reaction tube. In an argon atmosphere of 0.1 MPa, it was heated to 500 °C at a rate of 3 °C / min and calcined at 500 °C for 5 h to obtain a TiO2-based catalyst;

[0069] In an argon-protected glove box, 2 g of a mixture of the TiO2-based catalyst and MgH2 were weighed at a mass ratio of 5:95 and loaded into a ball mill tank. According to a ball-to-material ratio of 40:1, it was ball milled for 15 h at room temperature in an argon atmosphere of 0.1 MPa with a rotation speed of 150 rpm to obtain a MgH2 hydrogen storage material.

[0070] Referring to Example 1, the hydrogen absorption and dehydrogenation analysis tests were carried out on the MgH2 hydrogen storage material. The temperature-programmed dehydrogenation curve of the MgH2 hydrogen storage material is as follows Figure 6 shown. It can be seen that both the starting and peak dehydrogenation temperatures of the MgH2 hydrogen storage material compounded with the TiO2-based catalyst are relatively low. Among them, the starting dehydrogenation temperature is lower than 250 °C, and the peak dehydrogenation temperature is lower than 300 °C. In addition, after calculation, the MgH2 hydrogen storage material has a high hydrogen storage capacity of 7.16 wt%.

[0071] Example 5

[0072] In an argon-protected glove box, 3 g of sodium amide particles and TiO2 (anatase type) were weighed respectively at a mass ratio of 2:1, mixed and loaded into a stirring tank. In an argon atmosphere of 0.1 MPa, mechanical stirring was carried out at 30 °C at a rate of 1000 rpm for 5 h to obtain a TiO2-based catalyst;

[0073] In an argon-protected glove box, 2 g of a mixture of TiO2-based catalyst and MgH2 were weighed at a mass ratio of 5:95 and loaded into a ball-milling tank. According to the ball-to-material ratio of 40:1, ball milling was carried out at room temperature in an argon atmosphere of 0.1 MPa for 15 h, and the rotation speed was 150 rpm to obtain a MgH2 hydrogen storage material.

[0074] Using a self-made temperature-programmed instrument combined with a mass spectrometer, the starting temperature and peak temperature of the dehydrogenation of the MgH2 hydrogen storage material were detected and tracked. The specific test method is as follows;

[0075] In the glove box, 20 mg of the MgH2 hydrogen storage material was weighed and loaded into a reaction tube, and an argon carrier gas with a flow rate of 20 mL / min was introduced, and the temperature was raised to 400 °C at a heating rate of 2 °C / min, and the curve of the hydrogen signal detected by the mass spectrometer during the heating process changing with time and temperature was recorded.

[0076] The test results are as Figure 7 shown, Figure 7 which is the temperature-programmed dehydrogenation mass spectrometry curve of the MgH2 hydrogen storage material. It can be seen that the MgH2 hydrogen storage material starts to dehydrogenate slowly at 170 °C and reaches the highest dehydrogenation rate at 260 °C, indicating that the introduction of the TiO2-based catalyst can significantly reduce the starting and peak dehydrogenation temperatures of the MgH2 hydrogen storage material.

[0077] The surface morphology of the sample of the obtained MgH2 hydrogen storage material after dehydrogenation was characterized by a scanning electron microscope. The obtained SEM image is as Figure 8 shown. It can be seen that after dehydrogenation, regular sodium particles are present on the surface of the material.

[0078] Example 6

[0079] In an argon - protected glove box, 3 grams of sodium amide particles and TiO₂ (diamond - type) were weighed respectively at a mass ratio of 1:1, mixed and loaded into a stirring tank. In an argon atmosphere of 0.1 MPa, mechanical stirring was carried out at 30 °C at a rate of 500 rpm for 5 h to obtain a TiO₂ - based catalyst;

[0080] In an argon - protected glove box, 2 grams of a mixture of TiO₂ - based catalyst and MgH₂ were weighed at a mass ratio of 5:95 and loaded into a ball - milling tank. According to a ball - to - material ratio of 60:1, under an argon atmosphere of 0.1 MPa at room temperature, ball - milling was carried out for 10 h at a rotation speed of 150 rpm to obtain a MgH₂ hydrogen storage material.

[0081] Referring to Example 5, the obtained MgH₂ hydrogen storage material was subjected to hydrogen absorption and desorption tests. The temperature - programmed dehydrogenation mass spectrometry curve of the obtained MgH₂ hydrogen storage material is as Figure 9 shown. It can be seen that the MgH₂ hydrogen storage material starts to slowly dehydrogenate at 180 °C and reaches the highest dehydrogenation rate at 265 °C, indicating that the introduction of the TiO₂ - based catalyst can significantly reduce the initial and peak dehydrogenation temperatures of the MgH₂ hydrogen storage material and improve the dehydrogenation kinetic performance.

[0082] Example 7

[0083] This example provides a MgH₂ hydrogen storage material, and the preparation method is as follows:

[0084] In an argon - protected glove box, 2 grams of lithium amide particles and TiO₂ (rutile - type) were weighed respectively at a mass ratio of 1:2, mixed and loaded into a ball - milling tank. According to a ball - to - material ratio of 30:1, in an argon atmosphere of 0.1 MPa at 40 °C, ball - milling was carried out for 15 h at a rotation speed of 200 rpm to obtain a TiO₂ - based catalyst;

[0085] In an argon - protected glove box, 2 grams of a mixture of TiO₂ - based catalyst and MgH₂ were weighed at a mass ratio of 5:95 and loaded into a ball - milling tank. According to a ball - to - material ratio of 70:1, under an argon atmosphere of 0.1 MPa at room temperature, ball - milling was carried out for 10 h at a rotation speed of 200 rpm to obtain a MgH₂ hydrogen storage material.

[0086] Example 8

[0087] This example provides a MgH₂ hydrogen storage material, and the preparation method is as follows:

[0088] In an argon - protected glove box, 2 grams of lithium nitride particles and TiO₂ (anatase - type) were weighed respectively at a mass ratio of 1:1, mixed and loaded into a reaction tube. In an argon atmosphere of 0.1 MPa, the temperature was raised to 600 °C at a rate of 2 °C / min and calcined at 600 °C for 5 h to obtain a TiO₂ - based catalyst;

[0089] In an argon - protected glove box, 2 g of a mixture of TiO2 - based catalyst and MgH2 with a mass ratio of 5:95 was weighed and loaded into a ball - milling tank. According to a ball - to - material ratio of 40:1, under an argon atmosphere at room temperature and 0.1 MPa, ball - milling was carried out for 15 h at a rotation speed of 150 rpm to obtain the MgH2 hydrogen storage material.

[0090] Example 9

[0091] This example provides an MgH2 hydrogen storage material, and the preparation method is as follows:

[0092] In an argon - protected glove box, 3 g of sodium amide particles and TiO2 (anatase type) were respectively weighed according to a mass ratio of 1:1, mixed and loaded into a reaction tube. In an argon atmosphere of 0.1 MPa, it was heated to 400 °C at a rate of 5 °C / min and calcined at 400 °C for 5 h to obtain the TiO2 - based catalyst;

[0093] In an argon - protected glove box, 2 g of a mixture of TiO2 - based catalyst and MgH2 with a mass ratio of 5:95 was weighed and loaded into a ball - milling tank. According to a ball - to - material ratio of 40:1, under an argon atmosphere at room temperature and 0.1 MPa, ball - milling was carried out for 10 h at a rotation speed of 150 rpm to obtain the MgH2 hydrogen storage material.

[0094] Comparative Example 1

[0095] This comparative example provides a pure magnesium hydride material, and the preparation method is as follows:

[0096] In an argon - protected glove box, 2 g of magnesium hydride was weighed and loaded into a ball - milling tank. According to a ball - to - material ratio of 40:1, under an argon atmosphere at room temperature and 0.1 MPa, ball - milling was carried out for 10 h at a rotation speed of 150 rpm to obtain a pure magnesium hydride material without adding a catalyst.

[0097] The obtained pure magnesium hydride material was characterized by referring to the method in the reference example. Among them, the temperature - programmed dehydrogenation mass spectrometry curve of the pure magnesium hydride material is as Figure 10 shown, and the temperature - programmed dehydrogenation curve is as Figure 11 shown. From Figure 10 and 11 it can be seen that its initial dehydrogenation temperature is close to 300 °C, the peak dehydrogenation temperature is about 350 °C, and the temperature corresponding to the highest dehydrogenation rate is as high as 327 °C. Compared with the results obtained in the above examples, it shows that the dehydrogenation kinetic performance of the MgH2 hydrogen storage material compounded with the TiO2 - based catalyst provided by the present invention is significantly improved.

[0098] In addition, the present invention carried out a cyclic stability test on the hydrogen absorption and desorption of the MgH2 hydrogen storage material obtained in Example 1. The test method is as follows:

[0099] In the glove box, 150 mg of the MgH2 hydrogen storage material was weighed and loaded into the reactor. Isothermal cycling tests were carried out at 300 °C. The dehydrogenation process of the material was carried out at a pressure of 0.3 bar, and the hydrogen absorption process was carried out under a hydrogen backpressure of 30 bar. Dehydrogenation was carried out until the equilibrium hydrogen pressure was reached and then hydrogen absorption began. Hydrogen absorption was carried out until the equilibrium hydrogen pressure was reached and then dehydrogenation began. This process was repeated.

[0100] The test results are as Figure 12 shown, Figure 12 which is the cycling performance graph of the MgH2 hydrogen storage material. It can be seen that the MgH2 hydrogen storage material has excellent cycling stability. After continuous operation for 800 h, its hydrogen absorption and dehydrogenation kinetic performance has not decreased significantly.

[0101] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A TiO2-based catalyst, characterized in that, An alkali metal / alkaline earth metal, nitrogen anion-doped titanate composite is prepared by a reduction reaction between TiO2 and an alkali metal compound containing a nitrogen atom and / or an alkaline earth metal compound containing a nitrogen atom; The TiO2-based catalyst is prepared according to the following method: The TiO2 and an alkali metal compound containing a nitrogen atom and / or an alkaline earth metal compound containing a nitrogen atom are subjected to a reduction reaction in a protective atmosphere or a vacuum environment by any one of ball milling, calcination or stirring to obtain the TiO2-based catalyst; The pressure of the calcination is 0.01 to 10 bar.

2. The TiO2-based catalyst according to claim 1, characterized in that, The alkali metal compound containing a nitrogen atom is selected from any one or more of nitrides, amino compounds or imino compounds of alkali metals; The alkaline earth metal compound containing a nitrogen atom is selected from any one or more of nitrides, amino compounds or imino compounds of alkaline earth metals.

3. The TiO2-based catalyst according to claim 1, wherein The mass ratio of the alkali metal compound containing a nitrogen atom and / or the alkaline earth metal compound containing a nitrogen atom to TiO2 is 1:(0.5 to 10).

4. The TiO₂-based catalyst according to claim 1, wherein The configuration of the TiO2 is a rutile structure and / or anatase structure.

5. The preparation method of the TiO2-based catalyst according to any one of claims 1 to 4, characterized in that, It includes the following steps: The TiO2 and an alkali metal compound containing a nitrogen atom and / or an alkaline earth metal compound containing a nitrogen atom are subjected to a reduction reaction in a protective atmosphere or a vacuum environment by any one of ball milling, calcination or stirring to obtain the TiO2-based catalyst.

6. The preparation method according to claim 5, wherein The pressure of the ball milling is 0.1 to 1 MPa, the temperature is 10 to 100 °C, the rotation speed is 50 to 600 rpm, and the ball-to-material ratio is (20 to 120):1; The pressure of the stirring is 0.1 to 10 MPa, the temperature is 10 to 100 °C, the time is 1 to 40 h, and the stirring rate is 500 to 30000 rpm; The pressure of the calcination is 0.01 to 10 bar, the temperature is 200 to 800 °C, the time is 1 to 20 h, and the heating rate is 1 to 10 °C / min.

7. The application of the TiO2-based catalyst according to any one of claims 1 to 4 or the TiO2-based catalyst prepared by the preparation method according to claim 5 or 6 in a hydrogen storage reaction.

8. A magnesium-based hydrogen storage material, characterized in that, It includes a catalyst and a magnesium-based material; The catalyst is the TiO2-based catalyst according to any one of claims 1 to 4 or the TiO2-based catalyst prepared by the preparation method according to claim 5 or 6.

9. The magnesium-based hydrogen storage material according to claim 8, wherein, The magnesium-based material is selected from any one or more of MgH2, magnesium powder, magnesium-based alloy hydrides or magnesium-based alloys.

10. The magnesium-based hydrogen storage material according to claim 8, characterized in that, The mass ratio of the catalyst to the magnesium-based material is (5 to 10):(90 to 95).

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