Renewable Energy Global Innovations features: Hydrogen storage properties and mechanisms of magnesium based alloys with mesoporous surface

Significance Statement

The United Nations Conference on Climate Change held in Paris charts the course for green, circular and low-carbon development featuring both economic growth and an effective response to climate change. One of the effective and sustainable methods is increasing the share of the renewable energy in the energy consumption structure.

Nowadays, hydrogen energy has been viewed as a kind of ideal renewable energy due to its non-pollution, abundant source and cyclic utilization. In order to achieve the practical applications of hydrogen energy, an efficient, safe and economic hydrogen storage technology is a key issue.

Mg-based metal hydride is one of the most promising candidates for hydrogen storage because of its low cost, high hydrogen storage capacity, good safety and environmental benignity. Unfortunately, high reaction temperature during hydrogen absorption/desorption processes imposes restrictions on the applications of Mg-based metal hydride. Lowering the reaction temperature has become crucial for Mg-based metal hydride hydrogen storage material.

Our research is aimed to reduce the hydrogen absorption/desorption temperature, thus improving the low-temperature hydrogen storage properties of Mg-based metal hydride, which is the hot topic in the field of hydrogen storage technology. A new kind of mesoporous material with the highly developed surface, called as HDS Mg-Ni hydride, is designed based on conventional Mg-based hydride. The new method of mechanically alloying and subsequent alkali washing was applied to prepare the HDS Mg-Ni hydride.

On the basis of our observations, the specific surface areas of this kind of Mg-based mesoporous material are 5~10 times as large as those of conventional Mg-based hydride. The larger specific surface area with abundant mesopores provides more and easier paths for the diffusion of hydrogen into the unreacted layer, thus facilitating the hydrogen absorption/desorption processes of Mg-based hydride. As a result, the HDS Mg-Ni hydride has favorable hydrogen storage properties at low temperatures. The hydrogen absorption/desorption temperature is remarkably reduced to near room temperature. According to a study on the hydrogen storage mechanisms, it was also found that the hydrogen storage capacity could be further increased by mixing other hydrogen storage materials into the HDS Mg-Ni; for example, activated carbon. The synergistic effects between the HDS Mg-Ni and activated carbon could lead to an increase of about 30% in the hydrogen storage capacity of the composite system. The improvements in the reaction temperature and hydrogen storage capacity make Mg-based metal hydride more attracting in the practical applications of hydrogen storage technology. Besides, it is significant and helpful in the design and development of new advanced Mg-based composite systems for hydrogen storage.

About The Author

Zhen Wu, Assistant professor, School of Chemical Engineering and Technology, Xi’an Jiaotong University. He received his Ph.D. degree in Power Engineering and Engineering Thermophysics from Xi’an Jiaotong University. From Sep 2013 to Sep 2014, he obtained the National Government Study Abroad Scholarship to make research in Kyoto University as a visiting scholar. Now he is undertaking the National Natural Science Foundation of China (No. 51506174), the General and Special Programs of China Postdoctoral Science Foundation (No. 2015M570830) and Fundamental Research Funds for the Central Universities (No. xjj2016047) as the project leader. In 2015, his paper published in Applied Energy was awarded as the ‘Best Paper Award of Excellence‘ jointly by Elsevier Publishing Co. Ltd. and the prestigious international journal of Applied Energy. His research interests include: 1) Design and development of advanced hydrogen storage materials. 2) Optimal design of hydrogen storage reactors. 3) System integration of on-board hydrogen source unit and energy management of integrated on-board hydrogen source system.

About The Author

Zaoxiao Zhang, Professor, Dean of Department of Chemical Process Equipment, Xi’an Jiaotong University. He received his Ph.D. degree in Power Engineering and Engineering Thermophysics from Xi’an Jiaotong University in 1998. During the period of 2001 – 2004, he successively worked in Japanese International Cooperation Agency (JICA) and the University of Queensland, Australia, as a visiting scholar. So far, he has undertaken more than 30 projects from the National Natural Science Foundation of China, Chinese Ministry of Education and the industries. His research work has been awarded by Chinese Ministry of Education, Beijing City Government and China Petrochemical Corporation (Sinopec Group), respectively. He has been involved with the research of energy system optimization. Since he has lots of cooperation experiences with the industries, he combines industrial demand and lab studies to build an interdisciplinary research program with emphasis on energy system and fossil fuel resources. An important research field in the last ten years is the energy and environmental technologies for the increase of the energy efficiency and reducing CO₂ emissions in the industrial processes. He has published more than 100 peer-reviewed papers, 10 patents, 5 academic monographs and delivered more than 50 presentations in academia and industry up till now.

About The Author

Fusheng Yang is an associate professor in the School of Chemical Engineering and Technology at Xi’an Jiaotong University, Xi’an, China. He got his Ph.D. degree at the same university in 2010 and once worked as postdoctoral researcher at Tokyo University of Science, Noda, Japan. His present research interests include: 1) Development of novel metal hydride reactor prototype for heat & mass transfer enhancement. 2) Consistent measurement and modeling of P-C-T properties and intrinsic hydriding/dehydriding kinetics of metal hydride materials. 3) Industrial applications of energy saving techniques, such as steam ejector based heat pump. He has published about 20 peer-reviewed journal papers, 1 book chapter, and delivered ~10 presentations in academia and industry.

About The Author

Penghui Feng is currently a Ph.D. candidate in the major of Power Engineering and Engineering Thermophysics in School of Chemical Engineering and Technology at Xi’an Jiaotong University. He focuses on the research of high temperature thermal storage technology based on metal hydrides. 

About The Author

Yuqi Wang received his Ph.D. degree from Xi’an Jiaotong University specializing in power engineering and engineering thermophysics. Now he is currently a professor in School of Chemical Engineering at Northwest University. From Mar 2009-Sep 2009, he worked in Low Carbon Green Technology Laboratory, University of Nevada(Reno) as a visiting scholar. Dr. Wang proposed several new type of metal hydride reactors and conducted a few simulation study on metal hydride heat pumps and thermal compressors. Now he is undertaking 6 projects including Natural Science Foundation of China and other projects from Ministry of Science and Technology, Shaanxi government. He has published more than 60 academic papers, authorized 10 national invention patents, and he was awarded 22 teaching and scientific research prizes, like “the China Young Backbone Teacher Scholarship” and “the second prize of Science and Technology at Shaanxi Institutions of Higher Learning (15C21)”. He was awarded in 2008. His research focuses on: 1) H₂ storage kinetics and investigation of metal hydride reactor. 2) Chemical energy engineering and hydrogen Energy. 3) Supercritical fluid technology. 4) Reforming and transfer reaction of CH₄ and utilization of clean energy.

Journal Reference

International Journal of Hydrogen Energy, Volume 41, Issue 4,  2016, Pages 2771-2780.

Z. Wu¹, Z.X. Zhang^1,2, F.S. Yang¹, P.H. Feng¹, Y.Q. Wang³ 

Show Affiliations

1. School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
2. State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
3. School of Chemical Engineering, Northwest University, Xi’an 710069, People’s Republic of China

Abstract

A new kind of magnesium based hydrogen storage alloy with highly developed surface (HDS) was prepared using the technique of mechanical alloying followed by alkali washing in this paper. The phase composition, morphology, hydrogen storage properties and mechanisms of the alloy thus prepared, named HDS Mg-Ni, were further investigated by multiple methods including X-ray diffraction, scanning electron microscope, Sieverts volumetric method and differential scanning calorimeter. The specific surface area, average pore size and pore volume of the alloy are 50.95 m² g⁻¹, 36.2 nm and 0.34 cc g⁻¹, respectively. Also, it was discovered that the HDS Mg-Ni powder takes in about 0.65 wt.% of hydrogen even at a low temperature of 323 K, at which the conventional Mg and Mg₂Ni materials could not react with H₂. It suggests that the highly developed surface remarkably improves the hydrogen storage properties at low temperatures. Besides, the synergistic effects between the HDS Mg-Ni powder and activated carbon(AC) on the improvement of low-temperature behaviors were discussed. The results showed that the addition of AC further improves the hydrogen capacity and absorption kinetics due to the increased specific surface area, providing easier and more paths for the diffusion of hydrogen into the alloy powder.

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