Research and development of the hottest hydrogen s

Research and development of hydrogen storage technology Preface

in recent years, due to the rapid increase of traditional energy consumption and the increasingly serious problem of environmental pollution, many countries have carried out large-scale exploration of new energy, among which hydrogen energy is one of the important secondary energy

hydrogen is a kind of clean energy. When burning, it does not produce soot and SOX that pollute the environment. Its combustion product is water, which does not destroy the material cycle of the earth. People place great expectations on the development of hydrogen energy technology. In order to develop a hydrogen energy system, it is necessary to solve the problems of economic and mass production process of hydrogen, safe and economic hydrogen storage and transportation methods, safe and pollution-free combustion methods, fuel cells and other utilization methods. The storage and transportation of hydrogen is one of the keys

fuel cell is one of the most promising systems to use hydrogen energy. It is a device that directly converts the chemical energy of hydrogen and oxygen into electrical energy. Its characteristics are: high energy conversion rate, diversified fuels, clean exhaust, low noise, less environmental pollution, good reliability and maintainability, etc. However, as the hydrogen source of fuel cell, there are still many problems, which seriously restrict the application of fuel cell. In order to promote the practicality of fuel cells, the most economical and convenient way of hydrogen storage should be found

II Development status at home and abroad

at present, high-pressure gas and liquid methods are mostly used for the transportation and storage of hydrogen. In recent years, solid-state hydrogen storage technology has attracted attention. Using hydrogen storage materials to store and transport hydrogen has the following characteristics: (1) high volumetric hydrogen storage density; (2) No need for high-pressure containers and insulated containers: (3) good safety, no explosion hazard; (4) High purity hydrogen can be obtained. Taking the hydrogen storage device of mmni4.5al0.5 hydrogen storage alloy as an example, compared with the previous 150atm high-pressure gas cylinder, the volume of its container is only 1/4 of that of the high-pressure gas cylinder under the same hydrogen storage capacity. In this way, the volume of the whole system becomes smaller, so that the amount of hydrogen transported by the vehicle increases correspondingly, and the pressure of the container is reduced to less than 10ATM, which improves the safety. At the same time, it also improves the purity of hydrogen (99.9999% high-purity hydrogen can be obtained from this device), which increases the added value of hydrogen

at present, the problems existing in the large-scale application of hydrogen storage materials are: first, how to improve the hydrogen storage capacity of hydrogen storage materials; second, how to reduce the cost of materials and save precious metal resources

ti Mn hydrogen storage alloy is a nickel free hydrogen storage alloy suitable for large-scale engineering applications because of its low cost, and China is a country rich in titanium. In practical engineering applications, Ti Mn alloy has been widely used because of its large hydrogen storage capacity and excellent platform characteristics. According to the research of Takeshi Pusheng and others in Japan, ti1-xzrxmn2-y-zcrzvy (x=0.1~0.2, y=0.2, z=0.2~0.6) alloy has good hydrogen storage characteristics without heat treatment. In the five element system, the hydrogen storage ring ratio of ti0.9zr0.1mn1.4v0.2cr0.4 with a reduction of 5.8pct is the best. The maximum hydrogen absorption capacity is h/m ~ 1.07, that is, 240ml/g, and the maximum hydrogen release capacity is 233ml/g. In order to further reduce the cost of the alloy, Zhejiang University has carried out a study on substituting ferrovanadium alloy for pure V, and substituting Al, Ni for Zr. It is found that ti0.9zr0.2mn1.4cr0.4 (V-Fe) 0.2 has good hydrogen storage characteristics and platform characteristics. At 30 ℃, the hydrogen absorption capacity is 240ml/g, and the hydrogen evolution rate is 94%. The hydrogen storage capacity of ti0.98zr0.02v0.45fe0.1cr0.05mn1.4 alloy developed by Benz company in Germany reaches 2.0wt.%, The platform features are also very good. Japanese E. Akiba et al. Studied the TIV solid solution alloy, and the developed ti25cr30v40 alloy has a hydrogen storage capacity of 2.2wt.%

magnesium based alloys belong to medium temperature hydrogen storage alloys, and their hydrogen absorption and desorption properties are relatively poor. However, due to their large hydrogen storage capacity, light weight, rich resources and low price, many scientists are committed to developing new magnesium based hydrogen storage materials. After a long time of exploration and research, it is found that the hydrogen absorption and desorption properties of the alloy formed by adding a single metal to mg or Mg2Ni cannot be changed much, while adding a certain weight percentage of other series of hydrogen storage alloys (such as TiFe, TiNi, etc.) to mg or Mg2Ni will achieve unexpected results. Mandal et al. Found that adding a certain amount of TiFe and LaNi5 to Mg can significantly catalyze the hydrogen absorption and desorption properties of Mg. Such as mg+40wt.% FETI (MN), hydrogen absorption 3.3wt.% at room temperature, Moreover, at room temperature of 30atm, 80% hydrogen can be absorbed within 10 minutes and saturated within 40 minutes. Mechanical alloying of magnesium alloys can also effectively improve the dynamic properties of hydrogen absorption and desorption of magnesium alloys

in 1998, the International Energy Agency (IEA) determined the standard for new hydrogen storage materials in the future. Its hydrogen storage capacity should be greater than 5wt%, and it can absorb and release hydrogen under mild conditions. According to this standard, most of the current hydrogen storage alloys can not meet this performance requirement. Therefore, in addition to improving the existing metal based hydrogen storage materials, scientists all over the world have also been working to find new solid-state hydrogen storage methods:

1) carbon nanotubes

carbon nanotubes are a kind of carbon materials with large surface area. The material size is very small, usually 1 ~ 100 μ m. Therefore, it has a very large surface area; At the same time, carbon nanotubes contain many micropores with uniform size. In this way, when hydrogen reaches the material surface, on the one hand, it is adsorbed on the material surface; On the other hand, under the action of capillary force, hydrogen is compressed into micropores. Under the action of this capillary force, hydrogen can change from gaseous state to solid state. Therefore, this material can store a considerable amount of hydrogen. The current experimental results show that the hydrogen storage capacity can reach 8.4wt.% at 82k and 0.07MPa hydrogen pressure. Researchers are working to improve the hydrogen storage performance of this material near room temperature

2) graphite nanofibers

recently, Dr. Nelly Rodriguez and Dr. Terry Baker of Northeastern University in the United States claimed that they had found a new hydrogen storage material. Using this material can increase the mileage of fuel cell vehicles to 8000km in the future. This material is called graphite nanofiber, and its typical size is 5 ~ 100 μ m. The diameter is 5 ~ 100nm. Its hydrogen storage density can reach 75wt.%, That is, 1 gram of graphite nanofibers can store 3 grams of hydrogen. Dr. Cheng Huiming of Shenyang Metal Institute and others repeatedly obtained more than 8 wt% hydrogen storage capacity by using self-made graphite nanofibers in early November last year. Although the research of this material is still in the laboratory stage, and there are still deficiencies. However, once the research is successful and popularized, it may bring a new revolution to the hydrogen storage technology, so as to promote the development and application of the whole hydrogen energy system

3) carbon gel

carbon gel is a substance similar to foamed plastics. This material is characterized by ultra-fine pores, large surface area, and a solid matrix. It is usually obtained by supercritical separation and pyrolysis of resorcinol and formaldehyde solution after polycondensation at 1050 ℃ in an inert atmosphere. This material has a nanocrystalline structure, and its micropore size is less than 2nm. Recent test results show that its hydrogen storage capacity can reach 3.7wt.% at a high pressure of 8.3mpa

4) glass microsphere

the size of this material is 25 ~ 500 μ M, the thickness of the spherical wall is only 1 μ m。 In the range of 200 ~ 400 ℃, the penetrability of the material increases, so that hydrogen can be immersed into the glass under a certain pressure. When the temperature drops to near room temperature, the penetration of the glass body disappears, and then hydrogen can be released with the increase of temperature. It is found that this material can store 10wt.% hydrogen under the hydrogen pressure of 62mpa, After testing, 95% of the microspheres contain hydrogen, and at 370 ℃, the whole hydrogen absorption or desorption process can be completed within 15 minutes

there are two kinds of hydrogen storage devices using hydrogen storage materials: fixed and mobile. As a fixed hydrogen storage device, its volume should be small, and the mobile hydrogen storage device should be light and have large hydrogen storage capacity

the research and development of various hydrogen storage devices are shown in Table 1. Table 1 Performance list of metal hydride hydrogen storage containers in the world

name of manufacturer type hydrogen storage capacity (M3) hydrogen storage alloy remarks Brookhaven National Laboratory (USA) internal cold and hot type internal cold and hot type 70260tife 400kg 1.56% tife0.9mn0.1 1700kg, 1.36% diameter 300mm, hydrogen pressure 3.5Mpa diameter 660mm, hydrogen pressure 3.4mpa Mannesmann company Daimler Benz (Germany) internal isolation, external cold and hot 2000ti0.98zr0.02v0.43fe0.09cr0.05mn1.5 10t 1.78% hydrogen pressure 5.0mpa, temperature 100 ℃ 7 ×Φ 114.3mm Osaka Industrial Technology Testing Institute sunshine plan (Japan) is internally equipped with an isolation wall type 16mmni4.5mn0.5 106kg, 1.34% 250 ×Φ 750mm, hydrogen pressure 0.8MPa, temperature 80 ℃, Japan Institute of Chemical Technology (Japan) internal cold and hot 240mmni5 series alloy 1200kg, 1.78% three containers, high pressure 5MPa Φ 350, medium pressure 2MPa Φ 500, low pressure 1MPa Φ 500,80 ℃ Kawasaki Heavy Industry Research Institute (Japan) internal cold and hot 175ln Ni Al alloy 1000kg, 1.56% hydrogen pressure 0.7MPa, Kawasaki Heavy Industry Research Institute (Japan) internal cold and hot 20mmni4.5al0.5 120kg, 1.48% diameter 165mm, length 2280mm

Osaka hydrogen Industry Research Institute (Japan) multi tube, atmospheric heat exchange 134.4ti Mn series, tifemn series, 672kg, 1.78% hydrogen pressure 3.3 ~ 3.5Mpa, normal temperature Nippon Steel Research Institute.(Japan) internal hot and cold type 68ti0.95femm0.08 400kg, 1.5% diameter 381mm, length 1955mm, temperature 85 ℃, hydrogen pressure 3Mpa, atmospheric heat exchange type 70mm Ni Fe 480KG, 1.3% 16 Al alloy pipes, p=0.2mpa, flow 7m3/h, manufacturer name, type hydrogen storage capacity (M3) hydrogen storage alloy remarks Japan's joint Oxygen Company Automotive 11.3mmni4.5mn0.570kg, 1.44% pressure vessel 21l, 80 ℃ hydrogen release, 141.6 (12.6kg) TiFe 1002kg, 1.26% hydrogen storage container weight 400kg, It is used in 19 people's bread postal car. Japan Heavy Chemical Industry Corporation multi tube type 1.6fe0.94ti0.96zr0.04nb0.0410kg, 1.42% alloy powder is filled in Al foam, and the hydrogen release rate is 80l/min. Japan Panasonic Electric Appliance Corporation multi tube type 2.9timn1.5, 7.7kg (?) 28 pieces Φ 25.4al tube composition (with fins) German Mannesmann automotive 17ti-v-fe-mn alloy 80kg, 1.89% 1005 × three hundred and eighty × 145mm, total weight 140kg, 0.2MPa German Benz 60.7 (5.4kg) low temperature Ti Cr Mn 2%, high temperature Mg2Ni storage box total weight 340kg, the box accounts for about 30% tizrcrmn alloy 280kg, 1.93% storage box total weight 360kg, the box accounts for 22% 38.2 (3.4kg) 190kg, 1.79% storage box total weight 245kg, the box accounts for 22%

in order to further improve the performance of hydrogen storage device, we should further strengthen the optimization of internal structure of hydrogen storage container, the optimization of hydrogen absorption and desorption conditions and container materials.Lightweight research

at present, only Toyota of Japan has developed a hydrogen storage device using metal hydride for hydrogen storage in fuel cell vehicles in the world. In addition, the United States is conducting the test of a fuel cell driven golf cart using metal hydride for hydrogen supply. In the application of fuel cell miniaturization, American hydrogen energy company has developed a fuel cell driven wheelchair for the disabled and a portable fuel cell power supply with a power of 40 watts, which can be used for portable computers, portable radios or other portable devices; The Japanese company has developed a small fuel cell lighting power supply by using metal hydride to provide hydrogen; Canada Ballard company developed and rotated the upper collet handle to grasp the upper end of the wire to produce a titanium metal hydride hydrogen storage device matched with the fuel cell in the notebook computer; At present, the development of practical fuel cells in China has just started, but with the growth of social demand and the progress of science and technology, the application of fuel cells will be more and more widely. Now Taiwan has great interest in fuel cell driven motorcycles, so it is promising to carry out research on fuel cell hydrogen sources