Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5146700 | International Journal of Hydrogen Energy | 2017 | 9 Pages |
Abstract
According to catalytic effects of TiO2 on kinetic properties of hydrides and thermal conductivity of multiwall carbon nanotubes (MWCNTs) favoring heat transfer during de/rehydrogenation, improvement of dehydrogenation kinetics of compacted 2LiBH4-MgH2 by doping with MWCNTs decorated with TiO2 (MWCNTs-TiO2) is proposed. Via solution impregnation of Ti-isopropoxide on MWCNTs and hydrothermal reaction to produce TiO2, high surface area and good dispersion of TiO2 on MWCNTs surface are obtained. Composite of 2LiBH4-MgH2 is doped with 5-15 wt. % MWCNTs-TiO2 and compacted into the pellet shape (diameter and thickness of 8 and 1.00-1.22 mm, respectively). By doping with 15 wt. % MWCNTs-TiO2, not only fast dehydrogenation kinetics is obtained, but also reduction of onset dehydrogenation temperature (ÎT = 25 °C). Besides, gravimetric and volumetric hydrogen storage capacities of compacted 2LiBH4-MgH2 increase to 6.8 wt. % and 68 gH2/L, respectively, by doping with 15 wt. % MWCNTs-TiO2 (â¼twice as high as undoped sample). The more the MWCNTs-TiO2 contents, the higher the apparent density (up to â¼1.0 g/cm3 by doping with 15 wt. % MWCNTs-TiO2). The latter implies good compaction, resulting in the development of volumetric hydrogen capacity. In the case of mechanical stability during cycling, compacted 2LiBH4-MgH2 doped with at least 10 wt. % MWCNTs-TiO2 maintains the pellet shape after rehydrogenation. Although increase of porosity (up to 30%), leading to the reduction of thermal conductivity, is detected after rehydrogenation of compacted 2LiBH4-MgH2 doped with 15 wt. % MWCNTs-TiO2, comparable kinetics during cycling is obtained. This benefit can be achieved from thermal conductivity of MWCNTs.
Related Topics
Physical Sciences and Engineering
Chemistry
Electrochemistry
Authors
Praphatsorn Plerdsranoy, Songwuit Chanthee, Rapee Utke,