Magnesium Boride Hydrogenation Modifiers for Storage
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Solution Overview
Problem
The challenge lies in overcoming the slow kinetics of reversible hydrogen release from magnesium borohydride (Mg(BH4)2), which is essential for practical on-board PEM fuel cell applications, and the high pressures and temperatures required for its synthesis, making it commercially undesirable.
Innovation Solution
A method to synthesize magnesium borohydride at lower temperatures and pressures by hydrogenating magnesium boride (MgB2) in the presence of modifiers such as ethers, arenes, graphene, metal hydrides, and metals, using mechanical milling, sonication, or thermal treatment to improve hydrogenation efficiency and cycling capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If magnesium borohydride is synthesized directly from decomposition product MgB2 using high pressure and temperature, then magnesium borohydride can be formed, but the process becomes commercially undesirable due to high costs and energy consumption
Solution Approach 1:
The patent introduces modifiers (catalysts) as intermediaries to facilitate the hydrogenation reaction of MgB2. These modifiers lower the activation energy required for the reaction, enabling synthesis at reduced temperatures and pressures. The catalyst acts as a mediator between hydrogen and MgB2, making the process commercially viable by reducing energy input requirements.
Solution Approach 2:
The patent fundamentally changes the reaction parameters by using catalytic modifiers that enable hydrogenation to proceed at temperatures below 400°C and pressures below 900 bars, compared to the conventional high-energy requirements. This parameter transformation makes the synthesis process economically and energetically feasible for commercial applications.
2Quantity of substance
If magnesium borohydride is used for hydrogen storage, then high gravimetric H2 density (14.7 wt% H2) is achieved, but the reversible release kinetics are extremely slow
Solution Approach 1:
The patent employs catalytic modifiers as intermediaries to accelerate the hydrogen release kinetics from magnesium borohydride. These catalysts provide alternative reaction pathways with lower activation energies, enabling rapid and reversible hydrogen release while preserving the high gravimetric density of 14.7 wt%. The catalyst mediates the decomposition and recombination processes, making the material suitable for practical fuel cell applications.
Solution Approach 2:
The patent changes the kinetic parameters of hydrogen release by introducing catalytic species that lower the activation energy barriers. This enables the material to release hydrogen rapidly at moderate temperatures, transforming it from a slow-kinetics material into one with practical release rates for on-board fuel cell systems while maintaining high hydrogen capacity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the synthesis temperature and pressure of magnesium borohydride, enhancing its hydrogen cycling capacity and making it suitable for hydrogen storage systems, including vehicle applications, by maintaining a hydrogen cycling capacity of ≥4 wt% and controlling hydrogen release.
Implementation Method 1
hydrogenating a quantity of a reaction mixture of magnesium boride, MgB2, in the presence of a modifier, wherein the hydrogenation is performed at a temperature at or below 300° C. and at a hydrogenation pressure at or below 1000 bar
Implementation Method 2
milling magnesium boride in the presence of sub-stoichiometric amounts of at least one of an ether, arene, graphene, metal hydride, and metal in an inert atmosphere
Implementation Method 3
controlling the release of hydrogen upon heating the modified magnesium boride in a hydrogen reservoir system
Data Source
AI summary
Some embodiments described herein provide for methods for synthesizing magnesium borohydride from hydrogenation of magnesium boride at moderate temperature and pressure in the presence of a modifier. The modifier may be in form of hydrides, liquid hydrogen carriers, ammonia borane, metallic species, croconate anion based materials, ethers, amines or imines, metal carbides, borides, graphene, arenes, magnesium, aluminum, calcium or ionic liquids. Some embodiments provide for charging magnesium boride in presence of a modifier at high pressure hydrogen while simultaneously heating the material. The modification in some instances may lead to an improved magnesium boride product with enhanced properties for application in other hydrogen storage systems.