CN112408317A - Carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material and preparation method thereof - Google Patents
Carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material, which is prepared from lithium aluminum hydride and carbon-loaded titanium dioxide TiO generated in situ2The material is prepared by mixing and mechanically milling @ C. The carbon-supported titanium dioxide TiO2The micro-morphology of @ C is a three-dimensional flower shape with the diameter of 1 mu m, and the micro-morphology is prepared by calcining a precipitate generated by heating butyl titanate in a mixed solution of glycerol and ethanol for reaction; carbon-supported titanium dioxide TiO2The addition amount of @ C is 2-8 wt% of the total mass. The preparation method comprises the following steps: 1) preparing carbon-supported titanium dioxide generated in situ; 2) preparing the carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material. The doping amount of the catalyst is 2-6 wt% for the application in the field of hydrogen storageWhen the hydrogen content is larger than percent, the hydrogen releasing temperature of the system is reduced to 57-69 ℃, and the hydrogen releasing quantity reaches 7.12-7.36 wt%. The invention has the following advantages: 1. the carbon-supported titanium dioxide generated in situ effectively reduces the hydrogen release temperature of the lithium aluminum hydride, and has high final hydrogen release amount; 2. has the advantages of low cost, simple preparation process, controllable reaction and easy large-scale preparation.
Description
Technical Field
The invention relates to the technical field of hydrogen storage materials of new energy materials, in particular to an in-situ generated carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material and a preparation method thereof.
Background
Traditional fossil energy such as petroleum and coal is gradually exhausted along with continuous use of human beings, so that the energy crisis caused by the depletion limits the development of the human society, and the search for green, efficient and renewable new energy to replace the fossil energy is common knowledge of all human beings and has achieved a great deal of research results. The hydrogen energy has the advantages of rich raw material sources, high energy density, environment-friendly products, renewability and the like, and becomes one of the most potential alternative energy sources at present. At present, the development and utilization of hydrogen energy mainly face three key problems of production, storage and transportation. Among them, how to safely and efficiently use hydrogen energy as a vehicle-mounted energy storage carrier is the research topic with the most challenging and commercial value at present. The traditional high-pressure liquid and gaseous hydrogen storage method has low efficiency, high production energy consumption and low use safety, restricts the commercial use of vehicle-mounted hydrogen storage, and the solid hydrogen storage technology has great research potential as a safe and efficient hydrogen storage method, and is a hydrogen storage method which is most likely to be used on a large scale in the future.
Lithium aluminum hydride (LiAlH)4) Has high hydrogen storage capacity(10.6 wt%) is considered to be one of the most potential solid-state hydrogen storage materials, but the characteristics of overhigh hydrogen release temperature, slow hydrogen release kinetics, poor reversibility and the like restrict the use of the solid-state hydrogen storage material as an on-vehicle energy storage carrier.
In recent years, researchers improve LiAlH through modes of doping modification, nanocrystallization, composite system construction, confinement and the like4The hydrogen storage performance of (1) namely, the hydrogen release temperature is reduced, and the hydrogen release kinetics and reversibility are improved. Among them, doping modification, i.e., addition of a carbon-based material and various transition metal compounds (oxides, chlorides, nitrides, and the like), has been studied more. Reported examples are MWCNT and NiCl2、Nb2O5And TiN etc. are effective in reducing LiAlH4The initial hydrogen evolution temperature of (1).
Titanium dioxide (TiO)2) The composite material is a common material in daily production and life, has the characteristics of simple preparation, low cost, no toxicity, no pollution and the like, and is widely applied to the industrial production of coatings, plastics, papermaking, printing ink, chemical fibers, rubber, cosmetics and the like. Besides the application of titanium dioxide in the above fields, much research is carried out on the hydrogen release performance of doped modified hydrogen storage materials, such as MgH2And NaAlH4Modification studies, and is believed to be on MgH2、NaAlH4One of the catalysts with the best hydrogen release catalytic effect.
Doping titanium dioxide with modified lithium aluminum hydride (LiAlH)4) There are also a few studies reporting hydrogen evolution performance. Rangsubvigt et al used 10 wt% TiO2Doping catalytic LiAlH4The initial hydrogen release temperature of the system is reduced to 95 ℃, and the final hydrogen release amount reaches 7.0 wt% [ Rangsubevit P, Purasaka P, Chaisuwan T, et al. Effects of carbon-based materials and catalysts on the hydrogen desorption/adsorption of LiAlH [ ]4[J]. Chemistry Letters, 2012, 41(10): 1368-1370.]. However, TiO2Doping catalytic LiAlH4The initial hydrogen discharge temperature of (a) is higher than the operating temperature (ambient temperature) of the vehicle-mounted hydrogen storage system specified by the U.S. department of energy, and needs to be further improved.
Zhao Y et al react TiO2doping/C to LiAlH4Addition of (25 wt% TiO) was found2+38 wt% of C) toLiAlH4When the hydrogen release temperature is reduced to 64 deg.C, the hydrogen release amount is less than 5.0 wt% [ ZHao Y, Han M, Wang H, LiAlH ]4 supported on TiO2/hierarchically porous carbon nanocomposites with enhanced hydrogen storage properties[J]. Inorganic Chemistry Frontiers, 2016.]. The target hydrogen storage mass density of 5.5 wt% of the on-board hydrogen storage system specified by the U.S. department of energy was not achieved.
Separately using TiO for the above two works2、TiO2doping/C to LiAlH4Modified to LiAlH4The hydrogen release performance is improved to a certain extent, but the two works respectively have the problems that the initial hydrogen release temperature is higher, and the final hydrogen release amount is reduced due to the addition of a large amount of catalyst. Comparing the work of Rangsubevigt and Zhao Y, both are shown by LiAlH4As hydrogen storage material, TiO is used2、TiO2The hydrogen-releasing performance of the catalyst is improved due to TiO2The addition amount is increased and the carbon material C is added so that the addition amount is increased to LiAlH4The catalytic effect of (3) is more remarkable.
However, the inventors have found that the catalytic effect of the catalyst does not simply become better with an increase in the amount of the catalyst added, but depends on the specific electronic structure of the catalyst itself, that is, the root of the above problems lies in solving the electronic structure of the catalyst and LiAlH4The problem of matching.
Disclosure of Invention
The invention aims to provide a carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material and a preparation method thereof.
The inventor researches and discovers that: the carbon material has electronegativity, when the titanium dioxide is loaded on the carbon material in situ, the composite material of titanium dioxide loaded by carbon shows electronegativity as a whole through the interaction between the two materials, and the electronegativity can induce Li+To ensure charge balance, [ AlH ]4]-The charge of the group is changed, so that the instability of Al-H bond is caused, the dissociation of H is facilitated, and the LiAlH is realized4The hydrogen discharge has better effect.
The inventors theorize hereOn the basis of the TiO provided by the invention2@ C doped LiAlH4The hydrogen storage material is regulated to effectively control LiAlH4The hydrogen discharging process of the hydrogen storage material simultaneously realizes the following 2 technical effects:
1. reducing the initial hydrogen release temperature in the hydrogen release process;
2. the addition amount of the catalyst is reduced, so that more hydrogen is released in the whole hydrogen releasing process, and the final hydrogen releasing amount reaches 7.12 wt%.
In order to achieve the purpose of the invention, the invention adopts the technical scheme that:
a carbon-supported titanium dioxide doped lithium aluminum hydride hydrogen storage material is prepared from lithium aluminum hydride and carbon-supported titanium dioxide TiO generated in situ2Prepared by mixing and mechanically ball-milling the @ C and the carbon-loaded titanium dioxide TiO generated in situ2The micro-morphology of @ C is a three-dimensional flower-like morphology, the diameter of which is 1 μm; the in-situ generated carbon-supported titanium dioxide TiO2@ C is prepared by calcining the deposit generated by heating butyl titanate in the mixed solution of glycerin and alcohol
The addition amount of the carbon-supported titanium dioxide accounts for 2-8 wt% of the total mass.
The preparation method of the carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material comprises the following steps:
step 1) preparing carbon-supported titanium dioxide generated in situ, weighing glycerol, ethanol and butyl titanate according to a certain volume ratio, uniformly mixing the glycerol and the ethanol to serve as a solvent, dropwise adding the butyl titanate into the solvent under a certain condition, carrying out solvothermal reaction under a certain condition, washing and drying under a certain condition after the reaction is finished, and calcining under a certain condition to obtain carbon-supported titanium dioxide generated in situ;
in the step 1, the volume ratio of the glycerol to the ethanol to the butyl titanate is 5:15: 1;
the condition of dropwise adding the solvent into the butyl titanate in the step 1 is stirring condition, the stirring temperature is 20-30 ℃, the stirring speed is 40-60 rpm/min, and the stirring time is 5-8 min;
the conditions of the solvothermal reaction in the step 1 are that the temperature of the solvothermal reaction is 180 ℃ and the solvothermal reaction time is 24 hours;
the washing and drying conditions in the step 1 are anhydrous conditions to avoid hydrolysis, the specific conditions are that anhydrous ethanol is used as a detergent, filtering and washing are carried out for 3-4 times, the drying condition is vacuum drying, the drying temperature is 60-80 ℃, and the drying time is 10-12 hours;
the calcining condition in the step 1 is a nitrogen environment, the heating rate is 5-8 ℃/min, the calcining temperature is 450 ℃, and the calcining time is 3-4 h;
and 2) preparing the carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material, namely performing ball milling on the carbon-loaded titanium dioxide and the lithium aluminum hydride under a certain condition by taking the carbon-loaded titanium dioxide obtained in the step 1 to meet a certain mass fraction, so as to obtain the carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material.
The mass fraction of the carbon-supported titanium dioxide in the step 2 is 2-8 wt% of the total mass of the carbon-supported titanium dioxide;
the ball milling condition in the step 2 is argon protection, and the ball-to-material ratio is (60-40): 1, the ball milling speed is 400-.
The carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material is applied to the field of hydrogen storage,
when the doping amount of the catalyst is 2 wt%, the hydrogen releasing temperature of the system is reduced to 69 ℃, and the hydrogen releasing amount reaches 7.36 wt%;
when the doping amount of the catalyst is 6 wt%, the hydrogen releasing temperature of the system is reduced to 57 ℃, and the hydrogen releasing amount reaches 7.12 wt%.
In order to prove that the carbon-supported titanium dioxide material generated in situ is successfully prepared, an X-ray diffraction test is carried out on the carbon-supported titanium dioxide material, and the result is shown in figure 1, diffraction peaks appear in the obtained spectrum at 25.37 degrees, 48.12 degrees, 55.10 degrees and 62.74 degrees and respectively correspond to the (101), (200), (211) and (204) crystal faces of the titanium dioxide, and the carbon material is in an amorphous state and does not have corresponding diffraction peaks, which indicates that the carbon-supported titanium dioxide material is successfully prepared.
In order to prove the structural characteristics of the in-situ generated carbon-supported titanium dioxide material, the material prepared by the method has a three-dimensional flower-like shape with the diameter of 1 mu m through the test of a scanning electron microscope.
To demonstrate the mass of carbon and titanium dioxide in the in situ generated carbon-supported titanium dioxide material, comparison by TG tests in nitrogen and oxygen atmospheres indicated that the carbon content of the carbon-supported titanium dioxide material was 15 wt% and the titanium dioxide content was 85 wt%.
In order to prove the influence of the addition amount of the in-situ generated carbon-supported titanium dioxide as a catalyst on the hydrogen release performance of lithium aluminum hydride, TiO is prepared2TiO with @ C contents of 0 wt%, 2 wt%, 6 wt% and 8 wt%, respectively2@ C is a doped lithium aluminum hydride hydrogen storage material. The temperature rise dehydrogenation test is carried out to confirm that TiO is added2The initial hydrogen releasing temperature of the lithium aluminum hydride hydrogen storage material of @ C is 55-69 ℃, which is reduced by 85-99 ℃ compared with pure lithium aluminum hydride, and the total hydrogen releasing amount reaches 6.89-7.36 wt%.
Therefore, compared with the prior art, the invention has the following advantages:
1. the hydrogen storage material prepared by the invention effectively improves the hydrogen release performance of lithium aluminum hydride, has lower initial hydrogen release temperature, and obtains high final hydrogen release amount by adding a small amount of catalyst. When TiO is present2When the doping amount of @ C is 6 wt%, the initial hydrogen release temperature is reduced to 57 ℃, the final hydrogen release amount reaches 7.12 wt%, and the hydrogen release performance is greatly improved;
2. TiO prepared by the invention2The method used by @ C has the advantages of low cost, simple preparation process, controllable reaction, easy large-scale preparation and the like.
Description of the drawings:
FIG. 1 is a diagram of the TiO prepared according to example 1 of the present invention2The XRD pattern of @ C;
FIG. 2 is a three-dimensional flower-like TiO prepared according to embodiment 1 of the present invention2A field emission scanning electron micrograph of @ C;
FIG. 3 is a TG plot of the 80 ℃ vacuum dried product heated to 450 ℃ at a temperature rise rate of 5 ℃/min under nitrogen environment during the preparation of example 1 of the present invention;
FIG. 4 is a TG graph of a vacuum dried product at 80 ℃ in the preparation process of the embodiment 1 of the present invention, which is heated to 450 ℃ at a heating rate of 5 ℃/min in an oxygen environment;
FIG. 5 shows doped TiO of examples 1 to 3 of the present invention2LiAlH with @ C content of 6 wt%, 2 wt% and 8 wt%, respectively4The dehydrogenation graph of (a);
FIG. 6 is a 0 wt% TiO doped sample of comparative example 1 of the present invention2@ C LiAlH4The dehydrogenation graph of (a);
FIG. 7 shows the TiO prepared according to the embodiment of comparative example 2 of the present invention2Scanning electron microscope image of field emission.
FIG. 8 is a 6 wt% TiO doping of a specific comparative example 2 of the present invention2LiAlH of4The dehydrogenation graph of (a);
FIG. 9 shows CNTs/TiO prepared according to the embodiment of comparative example 3 of the present invention2A field emission scanning electron microscope image of (a);
FIG. 10 is a 6 wt% CNTs/TiO doped sample of specific comparative example 3 of the present invention2LiAlH of4The dehydrogenation graph of (a);
FIG. 11 is a CNTs-TiO doped 6 wt% according to a specific comparative example 4 of the present invention2LiAlH of4Dehydrogenation profile of (a).
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, which are given by way of examples, but are not intended to limit the present invention.
Example 1
A preparation method of a carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material comprises the following steps:
step 1) preparing carbon-supported titanium dioxide generated in situ, weighing glycerol, ethanol and butyl titanate according to a volume ratio of 5:15:1, uniformly mixing glycerol and ethanol to serve as a solvent, magnetically stirring the solvent at a rotating speed of 50 rpm/min at 25 ℃, dropwise adding butyl titanate into the solvent while stirring for 8 min, carrying out solvothermal reaction on the obtained mixed solvent at 180 ℃, wherein the reaction time is 24 h, washing the product for 3 times after the reaction is finished, and washing the product with absolute ethyl alcohol to avoid hydrolysis by using absolute ethyl alcohol as a washing agentDrying the washed product at 60 ℃ for 12 h in vacuum, heating the dried product to 450 ℃ at the heating rate of 5 ℃/min in the nitrogen atmosphere, and calcining for 3 h to obtain the in-situ generated carbon-supported titanium dioxide named TiO2@C；
Step 2) preparation of carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material, under the protection of argon, weighing 0.0300 g of TiO obtained in step 12@ C and 0.4700 g of lithium aluminum hydride under the protection of argon gas, the ball-to-feed ratio is 40: 1, ball milling at the ball milling speed of 450 r/min for 1 h to obtain TiO2The carbon-supported titanium dioxide doped lithium aluminum hydride hydrogen storage material with the doping amount of @ C being 6 wt percent.
In order to prove that the carbon-supported titanium dioxide material generated in situ is successfully prepared, an X-ray diffraction test is carried out on the carbon-supported titanium dioxide material, and the result is shown in figure 1, diffraction peaks appear in the obtained spectrum at 25.37 degrees, 48.12 degrees, 55.10 degrees and 62.74 degrees and respectively correspond to the (101), (200), (211) and (204) crystal faces of the titanium dioxide, and the carbon material is in an amorphous state and does not have corresponding diffraction peaks, which indicates that the carbon-supported titanium dioxide material is successfully prepared.
In order to prove the structural characteristics of the in-situ generated carbon-supported titanium dioxide material, the scanning electron microscope test shows that the material structure prepared by the method is a three-dimensional flower-like morphology with the diameter of 1 μm, and the result is shown in fig. 2.
To demonstrate the mass of carbon and titanium dioxide in the in situ generated carbon-supported titanium dioxide material, comparison by TG tests in nitrogen and oxygen atmospheres, as shown in fig. 3, 4, indicates that the carbon content of the carbon-supported titanium dioxide material is 15 wt% and the titanium dioxide content is 85 wt%.
The obtained TiO is2A temperature rise dehydrogenation test is carried out on the lithium aluminum hydride hydrogen storage material with the @ C content of 6 wt%, and the test method comprises the following steps: a proper amount of sample (600 mg-800 mg) is weighed, the temperature is increased to 300 ℃ at the heating rate of 2 ℃/min to test the hydrogen release performance of the hydrogen storage material, the detection result is shown in figure 5, the initial hydrogen release temperature is 57 ℃, the hydrogen release amount is 7.12 wt% when the temperature is increased to 300 ℃, and the hydrogen release rate reaches 98.2% of the theoretical value.
To demonstrate the effect of in situ generated carbon-supported titania as a catalyst on the hydrogen evolution performance of lithium aluminum hydride, a lithium aluminum hydride hydrogen storage material having a carbon-supported titania content of 0 wt% was prepared by comparative example 1.
Comparative example 1
Without adding TiO2Lithium aluminum hydride hydrogen storage materials of @ C, i.e. TiO2A method for producing a lithium aluminum hydride hydrogen storage material having a @ C content of 0 wt%, which comprises the same steps as in example 1 except that: in the step 2, TiO is not added2@ C, i.e. weighing only 0.5 g LiAlH4。
The obtained TiO is2A temperature-rising dehydrogenation test was carried out on a lithium aluminum hydride hydrogen storage material having a @ C content of 0 wt%, the test method was the same as in example 1, and the test results are shown in FIG. 6, in which the initial hydrogen desorption temperature was 154 ℃, the hydrogen desorption amount was 7.20 wt% when the temperature was raised to 300 ℃, and the hydrogen desorption rate reached 90.6% of the theoretical value.
As can be seen from a comparison of example 1 with comparative example 1, the in-situ generated carbon-supported titania as a catalyst reduced the initial hydrogen evolution temperature of lithium aluminum hydride from 154 ℃ to 57 ℃, and increased the hydrogen evolution rate from 90.6% to 98.2%.
To demonstrate the effect of the presence of carbon material in titania on the hydrogen evolution performance of lithium aluminum hydride, a titania-doped lithium aluminum hydride hydrogen storage material was prepared by comparative example 2.
Comparative example 2
The preparation method of the titanium dioxide doped lithium aluminum hydride hydrogen storage material comprises the same steps as the steps in the example 1 except that: the calcining atmosphere in the step 1 is air instead of nitrogen, and the obtained titanium dioxide is named as TiO2(ii) a In the step 2, TiO is weighed2Instead of TiO2@ C, to obtain TiO2Doped lithium aluminum hydride hydrogen storage materials.
To prove the TiO prepared2The structural characteristics of the material are tested by a scanning electron microscope, and the result is shown in figure 7, and the material structure prepared by the method is a three-dimensional flower-shaped appearance with the diameter of 2 mu m.
Will obtainTiO2The temperature-rising dehydrogenation test of the lithium aluminum hydride-doped hydrogen storage material was carried out in the same manner as in example 1, and the test results are shown in fig. 8, in which the initial hydrogen desorption temperature was 106 ℃, the hydrogen desorption amount was 6.99 wt% when the temperature was raised to 300 ℃, and the hydrogen desorption rate reached 96.4% of the theoretical value.
As can be seen by comparing example 1 with comparative example 2, the carbon-supported titania material containing carbon reduced the initial hydrogen evolution temperature of lithium aluminum hydride from 106 ℃ to 57 ℃, and increased the hydrogen evolution rate from 96.4% to 98.2%.
In order to prove the influence of the source mode of carbon in the carbon and titanium dioxide composite material on the hydrogen release performance of the lithium aluminum hydride, the carbon nanotube composite titanium dioxide doped lithium aluminum hydride hydrogen storage material was prepared by the comparative example 3.
Comparative example 3
A preparation method of a carbon nano tube composite titanium dioxide doped lithium aluminum hydride hydrogen storage material is the same as that of example 1 in steps which are not particularly described, and the difference is that: the step 1 is the preparation of the carbon nano tube composite titanium dioxide, but not the preparation of the carbon-loaded titanium dioxide generated in situ, and the preparation process of the carbon nano tube composite titanium dioxide comprises the following steps: weighing 0.1 g of CNTs, completely immersing the CNTs in 80 ml of 65% concentrated nitric acid, acidifying for 24 h, washing with deionized water for 3 times, carrying out suction filtration, drying for 10 h at 50 ℃ under vacuum condition, ultrasonically stirring 0.05 g of dried CNTs and 5 ml of butyl titanate for 4 h at 60 kHz, slowly dripping the obtained mixed suspension into 300 ml of deionized water, standing for 24 h, carrying out suction filtration, washing to neutrality at 60 ℃ under vacuum condition, drying for 12 h at 60 ℃, grinding a dried product, and then carrying out N-ion treatment on the obtained product2Heating to 400 ℃ at a speed of 5 ℃/min under the atmosphere condition, and keeping the temperature for 1 h to obtain the carbon nano tube composite titanium dioxide material named CNTs/TiO2(ii) a Step 2, weighing CNTs/TiO2Instead of TiO2@ C, to obtain CNTs/TiO2Doped lithium aluminum hydride hydrogen storage materials.
To demonstrate the CNTs/TiO prepared2The structural characteristics of the material, as measured by a scanning electron microscope, are shown in fig. 9, and the material prepared by the present invention has a structure of particles with a diameter of 2 μm and a surface loaded with 100 nm-sized agglomerated particles formed by fine wires.
The obtained CNTs/TiO2The temperature-rising dehydrogenation test of the lithium aluminum hydride-doped hydrogen storage material was carried out in the same manner as in example 1, and the test results are shown in fig. 10, in which the initial hydrogen desorption temperature was 100 ℃, the hydrogen desorption amount was 7.18 wt% when the temperature was raised to 300 ℃, and the hydrogen desorption rate reached 99.1% of the theoretical value.
As can be seen by comparing example 1 with comparative example 3, the carbon supported titania with in situ generated carbon reduced the initial hydrogen evolution temperature of lithium aluminum hydride from 100 ℃ to 57 ℃.
In order to demonstrate the influence of the source mode of carbon and titanium dioxide in the carbon and titanium dioxide composite material on the hydrogen release performance of lithium aluminum hydride, the mechanical ball milling carbon nanotube and titanium dioxide mixed composite material doped lithium aluminum hydride hydrogen storage material was prepared by comparative example 4.
Comparative example 4
A preparation method of a mechanical ball milling mixed carbon nanotube and titanium dioxide composite material doped lithium aluminum hydride hydrogen storage material is the same as that in example 1, except that: step 1, CNTs and TiO2Preparation of carbon-supported titanium dioxide for direct purchase, rather than in situ generation; in the step 2, 0.015 g of CNT and 0.015 g of TiO are weighed2Instead of 0.03 g TiO2@ C, namely CNTs-TiO2Doped lithium aluminum hydride hydrogen storage materials.
The obtained CNTs-TiO2The lithium aluminum hydride hydrogen storage material doped with the lithium aluminum hydride hydrogen storage material was subjected to a temperature-rising dehydrogenation test in the same manner as in example 1, and the test results are shown in fig. 11, in which the initial hydrogen-evolving temperature was 124 ℃, the hydrogen-evolving amount was 6.89 wt% when the temperature was raised to 300 ℃, and the hydrogen-evolving rate reached 95.1% of the theoretical value.
It can be seen from a comparison of example 1 with comparative example 4 that carbon and titanium dioxide, both carbon-supported titanium dioxide generated in situ, reduce the initial hydrogen evolution temperature of lithium aluminum hydride from 124 ℃ to 57 ℃ and increase the hydrogen evolution rate from 95.1% to 98.2%.
To obtain TiO2Optimum doping amount of @ C for lithium aluminum hydride hydrogen storage Material TiO was prepared by examples 2, 32@ C content of2, 8 wt% of carbon-supported titanium dioxide doped lithium aluminum hydride hydrogen storage material.
Example 2
Carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material (TiO)2@ C content 2% by weight), the procedure not specifically described being the same as in example 1, except that: in the step 2, TiO2The amount of @ C added was 2 wt%, and 0.0100 g of TiO was weighed in an argon atmosphere glove box, respectively2@ C and 0.4900 g LiAlH4。
The obtained TiO is2A temperature-rising dehydrogenation test was carried out on a lithium aluminum hydride hydrogen storage material having a @ C content of 2 wt%, the test method was the same as in example 1, and the test results are shown in FIG. 5, in which the initial hydrogen desorption temperature was 69 ℃, the hydrogen desorption amount was 7.36 wt% when the temperature was raised to 300 ℃, and the hydrogen desorption rate reached 97.4% of the theoretical value.
Example 3
Carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material (TiO)2@ C content 8 wt%), the same procedure as in example 1, except that: in the step 2, TiO2The amount of @ C added was 8 wt%, and 0.0400 g of TiO was weighed in an argon atmosphere glove box2@ C and 0.4600 g LiAlH4。
The obtained TiO is2A temperature-rising dehydrogenation test was carried out on a lithium aluminum hydride hydrogen storage material having a @ C content of 8 wt%, the test method was the same as in example 1, and the test results are shown in FIG. 5, in which the initial hydrogen desorption temperature was 55 ℃, the hydrogen desorption amount was 6.89 wt% when the temperature was raised to 300 ℃, and the hydrogen desorption rate reached 97.1% of the theoretical value.
Thus, TiO2The comprehensive hydrogen release performance of the lithium aluminum hydride hydrogen storage material with the @ C content of 6 wt% is optimal. As shown in FIG. 5, the initial hydrogen release temperature was 57 ℃, which is 97% lower than that of pure lithium aluminum hydride, and the hydrogen release rate reached 98.2% of the theoretical value, when the temperature was raised to 300 ℃.
Claims (8)
1. A carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material is characterized in that: titanium dioxide TiO supported on carbon generated in situ from lithium aluminium hydride2@ C mixing machineBall-milling to obtain the carbon-supported titanium dioxide TiO generated in situ2The micro-morphology of @ C is a three-dimensional flower-like morphology, the diameter of which is 1 μm; the in-situ generated carbon-supported titanium dioxide TiO2@ C is prepared by calcining the precipitate generated by heating butyl titanate in the mixed solution of glycerol and ethanol for reaction.
2. The in-situ generated carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material of claim 1, wherein: the carbon-supported titanium dioxide TiO2The addition amount of @ C is 2-8 wt% of the total mass.
3. The method of preparing a carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material as claimed in claim 1, wherein the method comprises the steps of:
step 1) preparing carbon-supported titanium dioxide generated in situ, weighing glycerol, ethanol and butyl titanate according to a certain volume ratio, uniformly mixing the glycerol and the ethanol to serve as a solvent, dropwise adding the butyl titanate into the solvent under a certain condition, carrying out solvothermal reaction under a certain condition, washing and drying under a certain condition after the reaction is finished, and calcining under a certain condition to obtain carbon-supported titanium dioxide generated in situ;
and 2) preparing the carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material, namely performing ball milling on the carbon-loaded titanium dioxide and the lithium aluminum hydride under a certain condition by taking the carbon-loaded titanium dioxide obtained in the step 1 to meet a certain mass fraction, so as to obtain the carbon-loaded titanium dioxide-doped lithium aluminum hydride hydrogen storage material.
4. The production method according to claim 3, characterized in that: in the step 1, the volume ratio of glycerol to ethanol to butyl titanate is 5:15:1, the amount of glycerol is 10-15 ml, the amount of ethanol is 30-45 ml, and the addition amount of butyl titanate is 2-3 ml.
5. The production method according to claim 3, characterized in that: the step 1 is that under the condition that the solvent is dripped into the butyl titanate, the stirring temperature is 20-30 ℃ and the stirring time is 5-8 min under the magnetic stirring condition that the rotating speed is 40-60 rpm/min; the reaction is carried out in a forced air drying oven, the reaction temperature is 180 ℃, and the reaction time is 24 hours; the condition of filtering and washing is to use absolute ethyl alcohol as a detergent to avoid product hydrolysis, and the filtering times are 3-4 times; the drying condition is vacuum drying, the drying temperature is 60-80 ℃, and the drying time is 10-12 h; the calcining conditions are that the heating rate is 5-8 ℃/min, the calcining temperature is 450 ℃, the calcining time is 3-4 h, and the calcining atmosphere is nitrogen.
6. The production method according to claim 3, characterized in that: the mass fraction of the carbon-supported titanium dioxide in the step 2 meets the condition that the addition amount accounts for 2-8 wt% of the total mass; the ball milling conditions are that argon is used as protective atmosphere, the ball-material ratio is (60-40): 1, the ball milling speed is 400-.
7. The application of the carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material as the hydrogen storage field according to claim 1 is characterized in that: when the doping amount of the catalyst is 2 wt%, the hydrogen releasing temperature of the system is reduced to 69 ℃, and the hydrogen releasing amount reaches 7.36 wt%.
8. The application of the carbon-supported titanium dioxide-doped lithium aluminum hydride hydrogen storage material as the hydrogen storage field according to claim 1 is characterized in that: when the doping amount of the catalyst is 6 wt%, the hydrogen releasing temperature of the system is reduced to 57 ℃, and the hydrogen releasing amount reaches 7.12 wt%.
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