scholarly journals Hydrogen Storage in Carbon and Oxygen Co‐Doped Porous Boron Nitrides

2020 ◽  
pp. 2007381
Author(s):  
Qunhong Weng ◽  
Lula Zeng ◽  
Zhiwei Chen ◽  
Yuxin Han ◽  
Kang Jiang ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Boron Nitrides ◽  
Co Doped

scholarly journals A Study of K/Ti-co-doped NaAlH4 on Thermodynamic Tailoring, Surplus Hydrogen Amount and Metal Hydride Molar Volume

2021 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Hydrogen Storage ◽  
Molar Volume ◽  
Metal Hydride ◽  
Chemical Potential ◽  
Reaction Pathway ◽  
Ideal Gas ◽  
Point Of View ◽  
Phase Point ◽  
Desorption Enthalpy ◽  
Co Doped

A remarkable finding of metal hydride hydrogen storage is that substituting 4 mol % sodium by potassium in 4 mol % Ti-doped NaAlH<sub>4</sub> raises the reversible hydrogen storage capacity from 3.3 % w/w H to 4.7 % w/w H. This increase by 42% is concomitant with a slightly lower desorption enthalpy: intriguingly enough, it is substantially more hydrogen capacity at slightly less desorption enthalpy. The general solution to that puzzle has been already derived from a gas phase point of view, taking advantage of the equilibrium nature of the matter, which thus comes in terms of an ideal gas chemical potential. However, it is also interesting to investigate for the flipside effect in the sorbent phase, affecting molar volume. This paper elucidates by the example of K/Ti-co-doped NaAlH<sub>4</sub> the relation of doping modifications to surplus hydrogen amount and hydride molar volume, defining the term “reaction pathway” in this context, yielding the according figures.<br>

The Effect of AlCl3 and Ti on Hydrogen Storage Performance of 4MgH2-Li3AlH6 System

2016 ◽  
Vol 852 ◽  
pp. 876-882
Author(s):  
Fang Yu ◽  
Fen Xu ◽  
Li Xian Sun ◽  
Xiang Fei Zhang ◽  
Lin Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Catalytic Activity ◽  
Hydrogen Storage ◽  
Onset Temperature ◽  
High Catalytic Activity ◽  
Storage Performance ◽  
Preparation Conditions ◽  
Solid Ball ◽  
Hydrogen Storage Performance ◽  
Co Doped

The AlCl3/Ti co-doped 4MgH2-Li3AlH6 has been successfully synthesized using solid ball-milled method. The effect of AlCl3/Ti and different preparation conditions on reversible hydrogen storage of 4MgH2-Li3AlH6 were investigated. It was found that the formed Al3Ti and Al can improve the de/rehydriding performance. The onset temperature of the system dehydrogenation decreased to 58 °C, and it can release hydrogen of 7.2 wt.% at 400 °C. The hydriding of the system was found that the adsorption rate greatly increased from 0.02 to 0.35 wt.% min-1. The activation energy (Ea) of MgH2 dehydrogenation decreased from 147 to 113.7 kJ mol-1 by adding additive AlCl3 and Ti. The AlCl3/Ti improved the thermodynamic and kinetic performance of the 4MgH2-Li3AlH6 composite, which was attributed to the high catalytic activity of Al3Ti and Al.

scholarly journals The Master Key to the Problem of Reversible Chemical Hydrogen Storage is 12 kJ (mol H2)-1

2021 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Hydrogen Storage ◽  
Storage Capacity ◽  
Ideal Gas ◽  
Equilibrium Thermodynamics ◽  
Ideal Gas Law ◽  
Chemical Hydrogen Storage ◽  
Co Doped ◽  
Normative Role ◽  
The Ideal

<p>This article shows up the intrinsic thermodynamic boundaries to reversible mass transfer on basis of the ideal gas law and classic equilibrium thermodynamics in relation to chemical hydrogen storage. In the event, a global picture of reversible chemical hydrogen storage is unveiled, including an explanation of partial reversibility. The findings of this work help to clarify problems of metal hydride chemistry which otherwise are difficult if not impossible to solve in convergent manner, e.g. why the substitution of 4 mol % Na by K in Ti-doped NaAlH<sub>4</sub> raises the reversible storage capacity by 42 % or the way the dopants take effect in (Rb/K)-co-doped Mg(NH<sub>2</sub>)<sub>2</sub>/2LiH. This work's result is of a wider significance since based on two cornerstones of physical chemistry and particularly for the normative role of hydrogen electrodes to electrochemistry.</p>

scholarly journals How to Assess the Relative Volume Change of Reversible Metal Hydrides Easily, Speedily and Concisely (Enough) with a Surprising Relevance for Clarifying Thermodynamic Tailoring Effects

2019 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Hydrogen Storage ◽  
Volume Change ◽  
Reaction Pathway ◽  
Metal Hydrides ◽  
Relative Volume ◽  
Reaction Parameters ◽  
Relative Volume Change ◽  
Open Issue ◽  
Chemical Hydrogen Storage ◽  
Co Doped

<p>A practical way for assessing the relative volume change of reversible metal hydrides upon hydrogenation, based on the van’t Hoff reaction parameters, is outlined. Hitherto computational methods can provide that information only at a much higher level of complexity. By that method, the open issue of assessing the minimum pressure for complete [AlH<sub>4</sub>]-formation in Ti-doped NaAlH<sub>4</sub> is resolved and the nature of the additional reaction pathway in KH/Ti-co-doped NaAlH<sub>4</sub> elucidated. This work summarizes the essentials for the thermodynamic tailoring of metal hydrides in nine points and adds thus a central missing piece to the puzzle of understanding reversible chemical hydrogen storage in metal hydrides.</p>

KH+Ti co-doped NaAlH4 for high-capacity hydrogen storage

2005 ◽  
Vol 98 (7) ◽  
pp. 074905 ◽  
Author(s):  
Ping Wang ◽  
Xiang-Dong Kang ◽  
Hui-Ming Cheng
Keyword(s):  
Hydrogen Storage ◽  
High Capacity ◽  
Co Doped

How to Assess the Relative Volume Change of Reversible Metal Hydrides Easily, Speedily and Concisely (Enough) with a Surprising Relevance for Clarifying Thermodynamic Tailoring Effects

2019 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Hydrogen Storage ◽  
Volume Change ◽  
Reaction Pathway ◽  
Metal Hydrides ◽  
Relative Volume ◽  
Reaction Parameters ◽  
Relative Volume Change ◽  
Open Issue ◽  
Chemical Hydrogen Storage ◽  
Co Doped

<p>A practical way for assessing the relative volume change of reversible metal hydrides upon hydrogenation, based on the van’t Hoff reaction parameters, is outlined. Hitherto computational methods can provide that information only at a much higher level of complexity. By that method, the open issue of assessing the minimum pressure for complete [AlH<sub>4</sub>]-formation in Ti-doped NaAlH<sub>4</sub> is resolved and the nature of the additional reaction pathway in KH/Ti-co-doped NaAlH<sub>4</sub> elucidated. This work summarizes the essentials for the thermodynamic tailoring of metal hydrides in nine points and adds thus a central missing piece to the puzzle of understanding reversible chemical hydrogen storage in metal hydrides.</p>

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