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Improving Hydrogen Storage Properties of LiBH4-MgH2 System by Doping Different Catalyst

Author: ZhangHongLiang
Tutor: ZhuMin
School: South China University of Technology
Course: Materials Processing Engineering
Keywords: Hydrogen storage materials MgH2 LiBH4 Catalyst Rare earth chloride
CLC: TG139.7
Type: Master's thesis
Year: 2010
Downloads: 93
Quote: 2
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Abstract


With the rapid development of global economy and the increasing demand for energy, mankind is facing the dual pressures of fossil energy depletion and deterioration of the ecological environment, so the development of significant new green energy. Hydrogen is an ideal energy carrier, hydrogen storage technology is the premise and foundation of the hydrogen scale application. In this thesis, the history and current situation of the development of hydrogen storage materials, LiBH4 and MgH2 representatives ligand hydrides and metal hydride hydrogen storage materials is an important application prospects because of its high hydrogen capacity. These two kinds of material absorbing and releasing hydrogen harsh conditions, poor dynamic performance issues to be resolved. This thesis problems MgH2 and LiBH4 exist, research. First, using high-energy ball milling method and add a different catalyst preparation LiBH4-MgH2 composites. Then study the milling process, catalyst type and amount of catalyst added LiBH4-MgH2 composite system put hydrogen performance. Test to measure the hydrogen storage properties of hydrogen desorption performance; using X-ray diffraction, scanning electron microscopy and other methods to characterize the organizational structure of the material after milling and hydrogen. The results showed that the particles of the LiBH4-of MgH2 composite system decreases gradually with increasing milling time, making the amount of hydrogen desorption kinetics gradual increase, but when the milling time to 10 hours, LiBH4-of MgH2 composite system particle size did not continue to reduce, but somewhat increased, decreased the amount of hydrogen desorption kinetics. In the same ball-powder ratio and milling time, the vibration milling composite system LiBH4-MgH2 hydrogen desorption kinetics than planetary ball better. Studies have shown that hydrogen desorption performance of different molar ratio LiBH4-MgH2 composite system, put the amount of hydrogen desorption kinetics increased with the increase in the content of MgH2. Hydrogen is divided into two phases, the first phase mainly the LiBH4 put hydrogen, and hydrogen second stage MgH2. And the hydrogen front and rear have LiBH4 exist, the the LiBH4 first step decomposition reaction is not fully carried out. Transition metal single quality Ni and Nb oxides TiO2 and Nb2O5, and chloride NiCl2, FeCl2 and YCl3 can improve desorption of LiBH4-MgH2 composite system performance. The catalyst in this thesis, Nb2O5 and YCl3 catalytic effect best, makes LiBH4 and MgH2 decomposition reaction can be carried out simultaneously. Catalytic effect of Ni and Nb LiBH4-MgH2 composite system put the amount of hydrogen is not obvious, and have the same catalytic effect of TiO2 and Nb2O5 on the amount of hydrogen, the catalytic effect of the YCl3 obvious, hydrogen desorption capacity increased by 2%. Rare earth chlorides of LaCl3, CeCl3, NdCl3, of SmCl3 can varying degrees improve LiBH4 and MgH2 hydrogen desorption capacity and desorption rate. LaCl3, CeCl3, NdCl3, SmCl3 desorption kinetics of MgH2 catalytic effect is basically the same. The desorption amount NdCl3 the catalytic effect of LaCl3, CeCl3, of SmCl3 and superior. MgH2 a discharge amount of hydrogen, and the hydrogen desorption rate is increased as the temperature rises. When the temperature reaches 350 ° C, the desorption amount of 7.5%, close to the theoretical hydrogen storage capacity of MgH2. Activated carbon load NdCl3 can effectively improve the dispersion and NdCl3 NdCl3 with MgH2 contact area, thus contributing to the raise NdCl3 catalytic role of MgH2. Adding 20wt% of NdCl3 on different molar ratio of the composite system of LiBH4-MgH2 have better catalysis, a molar ratio of 1:2 LiBH4-MgH2, 1 hour at 330 ℃ can emit 80% of its theoretical capacity of hydrogen . Moreover, with MgH2 content increases, LiBH4 a discharge amount of hydrogen increased.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > The alloy learn with a variety of properties of alloys > Other special nature of the alloy > Hydrogen storage alloy
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