Fundamental Material Properties of the 2LiBH4-MgH2 Reactive Hydride Composite for Hydrogen Storage: (II) Kinetic Properties

Abstract

Reaction kinetic behaviour and cycling stability of the 2LiBH 4-MgH 2 reactive hydride composite (Li-RHC) are experimentally determined and analysed as a basis for the design and development of hydrogen storage tanks. In addition to the determination and discussion about the properties; different measurement methods are applied and compared. The activation energies for both hydrogenation and dehydrogenation are determined by the Kissinger method and via the fitting of solid-state reaction kinetic models to isothermal volumetric measurements. Furthermore, the hydrogen absorption-desorption cycling stability is assessed by titration measurements. Finally, the kinetic behaviour and the reversible hydrogen storage capacity of the Li-RHC are discussed.

Tuning LiBH4 for Hydrogen Storage: Destabilization, Additive, and Nanoconfinement Approaches

“…Based on this analysis, it is clear that the mutual destabilization effect between LiBH 4 and MgH 2 only occurs upon hydrogenation, but at relatively low temperatures (<413 • C) under equilibrium conditions. For the hydrogenation process carried out under dynamic conditions, the applied temperatures were usually in the range between 300 • C and 400 • C [33][34][35][36][37][38][56][57][58][59][60][61][62][63][64][65][66][67]; hence, the mutual destabilization effect was verified by a one-step curve of hydrogen uptake against time. However, for the dehydrogenation, the thermodynamics limits the behavior of Li-RHC to two main reaction steps, losing the benefit of the destabilization effect.…”

“…The most applied approach to improve the kinetic behavior of the 2LiBH 4 + MgH 2 system was the addition of transition metal (TM) and transition metal compounds (TMC) via mechanical milling [68]. Several works were published about the improvement of the kinetic behavior, and also cycling stability of TM-and TMC-added Li-RHC [56][57][58][59][60][61][62][63][64][65][66][67]. In 2010, Bösenberg et al [57] studied the effects of TMC on the kinetic behavior of Li-RHC and proposed global reaction rate mechanisms for the absorption and mainly desorption of hydrogen.…”

“…Therefore, it was proposed that nanostructured TMB species can act as heterogeneous nucleation sites for MgB 2 , thus improving the dehydrogenation rate of the slowest step, i.e., the decomposition of LiBH 4 (second step), since the decomposition of MgH 2 is quite fast. Based on this concept, either TMBs were added to Li-RHC or TM, and TMC were used as sources to form in situ TMB through the interaction with the Li-RHC [40,[56][57][58][59][60][61][62][63][64][65][66][67]. Puszkiel et al [39,69] proposed another mechanism to explain the effect of a specific TMC on the kinetic behavior of Li-RHC.…”

Enrichment of Hydrogen from a Hydrogen/Propylene Gas Mixture Using ZIF-8/Water-Glycol Slurry

“…The demand for hydrogen is expected to increase in both the near and long terms, and, therefore, an effective hydrogen purification method is required. Many different approaches have been proposed for hydrogen production, but producing hydrogen from fossil fuels is by far the most common and commercially viable method [10,11]. Recently, hydrogen production via steam reforming processes from fossil fuel sources like propane, propene, isopropanol, and acetone was investigated [12][13][14], and a propylene byproduct was found among the products.…”

Effects of Native Vacancies on Nb-Doped MgH2 Using Density Functional Theory Calculations

“…During the last four decades the hydrogen storage in fuel cells and its subsequent reconversion to energy has been studied extensively. [6][7][8] This is mainly because the requirements for an effective, safe and reliable way to store hydrogen is not yet met. Storage it as gas can be dangerous and the ratio volume/capacity of storage is the lowest; on the other hand, storing hydrogen as a liquid require temperatures around 20 ºK and it make it energetically expensive.…”