A method for direct decomposition of magnesium-based hydrides driven by light

Abstract

The application discloses a method for directly decomposing magnesium-based hydride by light driving. The method is realized by a photolysis device, and the photolysis device comprises a reaction container, a light source, a buffer container and a water container. The light source is arranged on the oblique upper side of the reaction container, so that the magnesium-based hydride in the reaction container is decomposed and releases hydrogen under the irradiation of the light source. A hydrogen outlet is arranged on one side of the reaction container. One end of the buffer container filled with water is connected with the hydrogen outlet, and the other end is connected with the water container. The generated hydrogen amount is calculated through the water container. The method specifically comprises the following steps: after solid-phase ball milling treatment of the magnesium-based hydride, the ball-milled magnesium-based hydride is loaded in the reaction container of the photolysis device, and reacts under the irradiation of the light source of the photolysis device to directly decompose and obtain hydrogen. The method has the advantages of higher hydrogen production, greenness and controllable reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the hydrogen production technology field of hydride, in particular to a method for directly decomposing magnesium-based hydride driven by light. BACKGROUND

[0002] Since the 21st century, the energy crisis and environmental deterioration have appeared worldwide, forcing human society to develop various renewable clean energy. Solar energy is a rich renewable energy and has attracted widespread attention from researchers. Hydrogen energy, as a kind of green and efficient renewable energy, has a wide application market.

[0003] Mg-based hydride (such as MgH2) is a common hydrogen storage material system, which has the advantages of high energy storage density (2814kJ / kg), controllable decomposition temperature, abundant resources, low price, good safety, and high safety, and is the mainstream direction of energy storage materials. The research on Mg-based energy storage materials at present mainly focuses on the pyrolysis performance. The pyrolysis of Mg-based energy storage materials has problems such as high decomposition temperature, reduced thermal conductivity, and poor kinetic performance caused by sintering. In the heat storage reaction of Mg-based materials, two-step energy conversion (solar energy→thermal energy→hydrogen energy) is required, and the efficiency is low.

[0004] Dougherty et al. studied the decomposition performance of hydride (including MgH2, CaH2, SrH2 and BaH2) under ultraviolet light irradiation, but found that the hydrogen release amount was very low (for example, MgH2 could only release 0.0008wt% H2). SUMMARY

[0005] The present application solves the above-mentioned problems existing in the prior art, and the purpose of the present application is to provide a method for directly decomposing magnesium-based hydride driven by light. The method does not require water injection or catalyst addition in the hydrogen production reaction of magnesium-based hydride, has higher hydrogen production, and has the advantages of greenness and controllable reaction.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is: a method for directly decomposing magnesium-based hydride driven by light, which is realized by a photolysis device. The photolysis device comprises a reaction container, a light source, a buffer container and a metering container. The light source is arranged obliquely above the reaction container, so that the magnesium-based hydride in the reaction container decomposes and releases hydrogen gas under the irradiation of the light source. A hydrogen gas outlet is arranged on one side of the reaction container. One end of the buffer container filled with water is connected to the hydrogen gas outlet, and the other end is connected to a water container. The amount of hydrogen gas generated is calculated by the water container. The method specifically comprises the following steps: after solid-phase ball milling treatment of magnesium-based hydride, the ball-milled magnesium-based hydride is loaded into the reaction container of the photolysis device, and reacts under the irradiation of the light source of the photolysis device to directly decompose and obtain hydrogen gas.

[0007] In the photolysis device, the hydrogen generated in the reaction container enters the buffer container through the hydrogen outlet, so as to drive the water in the buffer container to enter the water container, which can be a metering container or a non-metering container, if it is a metering container, the amount of hydrogen generated in the reaction can be directly calculated, if it is a non-metering container, the water in the non-metering container can be weighed by a balance or other tools, and then the amount of hydrogen generated in the reaction can be calculated.

[0008] Generally, the particle size of the magnesium-based hydride is large (micron level), and the light absorption performance is not good. Through ball milling, the magnesium-based hydride can be reduced to nanoscale, and the nanoscale magnesium-based hydride can have better photolysis performance. After ball milling, the magnesium-based hydride reacts under the irradiation of the light source, and hydrogen is directly obtained by decomposition. At the same time, water does not need to be added or a catalyst is not needed in the reaction, and the reaction is more obvious. In addition, the photolysis performance of the magnesium-based hydride can be regulated by adjusting the light intensity and frequency. Therefore, the method has the advantages of higher hydrogen production and green and controllable reaction.

[0009] Preferably, the magnesium-based hydride is selected from one of MgH2, Mg2FeH6, NaMgH3, Mg2NiH4, a hydride of Mg-La alloy and a hydride of Mg-Li alloy.

[0010] Preferably, the solid-phase ball milling treatment adopts a swing ball mill or a planetary ball mill, the ball-to-material ratio is 35:1-45:1, the ball milling time is 6-8h, and the rotation speed is 350-450rpm.

[0011] Preferably, the power of the light source is greater than 40W, and the irradiation time is greater than 2min.

[0012] Preferably, the light source is ultraviolet light or visible light.

[0013] Further preferably, the ultraviolet light is ultraviolet light emitted by an ultraviolet lamp with a wavelength of 375-360nm.

[0014] Further preferably, the visible light is visible light emitted by a green light lamp with a wavelength of 530-520nm, a yellow light lamp with a wavelength of 595-585nm, a red light lamp with a wavelength of 732-725nm, or a blue light lamp with a wavelength of 470-465nm.

[0015] Compared with the prior art, the method for directly decomposing magnesium-based hydride driven by light irradiation has the advantages of higher hydrogen production, greenness and controllable reaction. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1is a schematic diagram of a device for hydrogen production by photolysis of magnesium-based hydrides driven by light;

[0017] Figure 2 is a picture showing the effect of hydrogen production by decomposition of MgH2 driven by different color visible light in Example 1;

[0018] Legend: 1, iron stand; 2, reaction bottle; 3, light source; 4, Monol wash bottle; 5, beaker; 6, electronic balance; 7, computer. DETAILED DESCRIPTION

[0019] The following examples are further illustrations of the application and are not intended to limit the application. Unless otherwise indicated, the materials used in these examples were obtained from common sources and used in accordance with conventional procedures generally employed by those skilled in the art. In the following examples, the planetary ball mill is a SP4 ball mill from Nan Da Instrument Factory.

[0020] The photolysis device comprises a reaction container, a light source, a buffer container and a water container. The light source is arranged obliquely above the reaction container, so that the magnesium-based hydride in the reaction container decomposes and releases hydrogen under the irradiation of the light source. A hydrogen outlet is arranged on one side of the reaction container. One end of the buffer container filled with water is connected to the hydrogen outlet, and the other end is connected to the water container. The amount of hydrogen generated is calculated through the water container. The method for directly decomposing magnesium-based hydrides driven by light proposed in the application can be carried out in a laboratory or as long as appropriate reaction conditions are provided. In the following examples, the reaction is carried out in a laboratory. The reaction container is preferably a reaction bottle, the buffer container is a Monol wash bottle, and the water container is a beaker.

[0021] As shown in Figure 1 , the reaction bottle 2 containing the magnesium-based hydride after ball milling and the light source 3 are placed on the iron stand 1. Under the irradiation of the light source 3, the magnesium-based hydride in the reaction bottle 2 decomposes and releases hydrogen, which pushes the water in the Monol wash bottle 4 to flow into the beaker 5 placed on the electronic balance 6. Finally, the electronic balance 6 is connected to analyze and record the amount of hydrogen produced by the computer 7.

[0022] The light source 3 can be ultraviolet light or visible light. The ultraviolet light is ultraviolet light emitted by an ultraviolet lamp with a wavelength of 375-360 nm. The visible light can be visible light emitted by a green light lamp with a wavelength of 530-520 nm, a yellow light lamp with a wavelength of 595-585 nm, a red light lamp with a wavelength of 732-725 nm, or a blue light lamp with a wavelength of 470-465 nm.

[0023] Example 1

[0024] A method for decomposing magnesium-based hydrides by ball milling and light irradiation includes the following steps: 2g of MgH2 and 80g of steel balls are ball-milled in a ball mill jar under an argon atmosphere of 1 atm for 5 hours at a speed of 400 rpm. After ball milling, the MgH2 is placed in a photocatalytic hydrogen production device and tested under blue, green, yellow, and red light irradiation, with each visible light having a power of 45W. The wavelengths of blue light are 470-465nm, green light 530-520nm, yellow light 595-585nm, and red light 732-725nm.

[0025] like Figure 2 As shown, MgH2 released 30.3 mL / g H2, 20 mL / g H2, 10.4 mL / g H2, and 10.0 mL / g H2 under 45W blue, green, yellow, and red light irradiation, respectively. Among these, ball-milled MgH2 released over 30 mL / g H2 (approximately 0.24 wt%) under 45W blue light irradiation. Compared to Dougherty et al., who only released 0.0008 wt% H2 when MgH2 was irradiated with ultraviolet light, the ball-milled MgH2 under light irradiation released over 0.24 wt% H2, indicating that this method effectively promotes the decomposition of MgH2.

[0026] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the direct decomposition of a magnesium-based hydride driven by light irradiation, characterized in that, The method is realized by a photolysis device, the photolysis device comprises a reaction container, a light source, a buffer container and a water container, the light source is arranged obliquely above the reaction container, so that the magnesium-based hydride in the reaction container is decomposed and releases hydrogen under the irradiation of the light source, a hydrogen outlet is arranged on one side of the reaction container, one end of the buffer container filled with water is connected with the hydrogen outlet, and the other end is connected with the water container, the generated hydrogen amount is calculated through the water container, and the method specifically comprises the following steps: after solid-phase ball milling treatment of magnesium-based hydride, the ball-milled magnesium-based hydride is obtained and is loaded in the reaction container of the photolysis device, and the ball-milled magnesium-based hydride is reacted under the irradiation of the light source of the photolysis device to directly decompose and obtain hydrogen; the light source is visible light, the visible light is visible light with a wavelength of 530-520 nm emitted by a green light lamp, visible light with a wavelength of 595-585 nm emitted by a yellow light lamp, visible light with a wavelength of 732-725 nm emitted by a red light lamp, or visible light with a wavelength of 470-465 nm emitted by a blue light lamp.

2. The method of direct decomposition of a magnesium-based hydride driven by light irradiation according to claim 1, characterized in that, The magnesium-based hydride is selected from one of MgH2, Mg2FeH6, NaMgH3, Mg2NiH4, a hydride of a Mg-La alloy and a hydride of a Mg-Li alloy.

3. The method of directly decomposing a magnesium-based hydride by light irradiation according to claim 1, characterized by, The solid-phase ball milling treatment adopts a swing ball mill or a planetary ball mill, the ball milling atmosphere is argon, the ball-to-material ratio is 35:1-45:1, the ball milling time is 6-8 h, and the rotating speed is 350-450 rpm.

4. The method of directly decomposing a magnesium-based hydride by light irradiation according to claim 1, characterized by, The power of the light source is greater than 40 W, and the irradiation time is greater than 2 min.

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