Project

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Influence of borane on the sorption of complex hydrides

Applicant Züttel Andreas
Number 129603
Funding scheme Project funding (Div. I-III)
Research institution Mobilität, Energie und Umwelt Empa
Institution of higher education Swiss Federal Laboratories for Materials Science and Technology - EMPA
Main discipline Physical Chemistry
Start/End 01.04.2010 - 31.03.2012
Approved amount 234'594.00
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All Disciplines (3)

Discipline
Physical Chemistry
Condensed Matter Physics
Inorganic Chemistry

Keywords (9)

tetrahydroborates; borane; hydrogen; storage; mechanism; sorption; hydrogen storage; complex hydrides; synthesis

Lay Summary (English)

Lead
Lay summary
Apart from being widely applied reagents in organic and inorganic synthesis, complex hydrides are ideal candidates to be used as future energy carriers. They can store high amounts of hydrogen per volume and hence present compounds with very high energy densities. In particular alkaline and alkaline-earth tetrahydroborates with one of the highest volumetric and gravimetric hydrogen capacity are intensively studied as hydrogen storage materials. However, due to thermodynamic and kinetic constraints, usually high pressures and temperatures have to be applied during hydrogen sorption. This is, especially for technical applications, a problem and the reason why they are not yet applied as hydrogen storage material. Much research has been performed on the synthesis of these compounds and their sorption behavior, however the mechanisms of formation and decomposition is far from being understood. An understanding of these mechanisms in tetrahydroborates is the basis for improving the sorption behavior and for a final application as hydrogen storage materials.For the synthesis and decomposition of tetrahydroborates, boron-hydrogen compounds, and in particular diborane, play an important role. Tetrahydroborates are known to emit diborane at lower temperatures as a decomposition product. This presents in particular a problem for reversible hydrogen storage. The material looses B to the gas phase, which is needed for a re-absorption process. Additionally, the emitted diborane is difficult to handle, since it is a toxic gas. The emission of diborane has to be avoided. Taking advantage of the low stability of diborane, there is reasonable hope to overcome this problem by application of appropriate catalysts. On the other side the preparation of tetrahydroborates has been shown by reacting metal -carbonates, -oxides, -hydroxides, -hydrides with diborane in solvents. Thereby the formation of B-H bonds originating from the borane seems to be important for the formation process. Understanding the role of borane during formation and decomposition of tetrahydroborates is an important step towards understanding the formation and decomposition processes of tetrahydroborates. This is the main objective of the project. The understanding of these mechanisms will serve as a basis for optimization of tetrahydroborates to be used in hydrogen storage. Characterizations by different complementing techniques will give new insights on structural, chemical, kinetic and thermodynamic properties of the system and its evolution during gas uptake and release.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Solvent-free synthesis and decomposition of Y(BH4)(3)
Remhof A, Borgschulte A, Friedrichs O, Mauron P, Yan Y, Zuttel A (2012), Solvent-free synthesis and decomposition of Y(BH4)(3), in SCRIPTA MATERIALIA, 66(5), 280-283.
Towards room temperature, direct, solvent free synthesis of tetraborohydrides
Remhof Arndt, Yan Yigang, Friedrichs Oliver, Kim Ji Woo, Mauron Philippe, Borgschulte Andreas, Wallacher D., Buchsteiner A., Hoser A., Oh K. H., Cho Y. W., Züttel Andreas (2012), Towards room temperature, direct, solvent free synthesis of tetraborohydrides, in Journal of Physics: Conference Series, 340, 1-8.
Impurity Gas Analysis of the Decomposition of Complex Hydrides
Borgschulte A, Callini E, Probst B, Jain A, Kato S, Friedrichs O, Remhof A, Bielmann M, Ramirez-Cuesta AJ, Zuttel A (2011), Impurity Gas Analysis of the Decomposition of Complex Hydrides, in JOURNAL OF PHYSICAL CHEMISTRY C, 115(34), 17220-17226.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Gordon Research Conference, Hydrogen-Metal Systems 17.07.2011 Stonehill College, 320 Washington St, North Easton, MA 02356, USA
5th European Conference on Neutron Scattering 17.07.2011 Prague, Czech Republic


Self-organised

Title Date Place
6th International Symposium Hydrogen & Energy 22.01.2012 Seminarhotel Stoos, Stoos, Switzerland

Abstract

In the project the influence of boron-hydrogen compounds on the formation and decomposition of tetrahydroborates is analyzed. The main objective is to understand the related mechanisms based on reactions of hydrogen/borane uptake and release. The understanding of these mechanisms will serve as a basis for optimization of tetrahydroborates to be used in hydrogen storage. Characterizations by different complementing techniques will give new insights on structural, chemical, kinetic and thermodynamic properties of the system and its evolution during gas uptake and release. Apart from investigations on the mechanisms, a new way of synthesis of tetrahydroborates is investigated and optimized. Since tetrahydroborates are widely applied reagents in organic and inorganic synthesis, this invention is of particular interest for the chemical industry. It will be protected by a patent. With respect to hydrogen storage a main goal is to find a catalyst, which promotes hydrogen and prevents borane release of tetrahydroborates at low temperatures. The hydrogen storage material looses B irreversibly via gaseous BHx, which is then missing for a re-absorption process. Furthermore, the emitted diborane is difficult to handle, since it is a toxic gas. Hence the prevention of the formation of borane is a main step towards reversible hydrogen storage in tetrahydroborates at low temperature, which is mandatory for future automotive applications. During the project I want to determine and evaluate the kinetics and thermodynamics of processes involving boranes and answer questions about reaction mechanisms and mass transport in the material. The synthesis I am going to perform is exposing metal hydrides to diborane atmosphere under heating and/or milling conditions. Thereby I want to shed light onto the reaction processes, whenever possible by “in situ” methods including Raman spectroscopy, X-ray diffraction, differential scanning calorimetry, neutron diffraction and gravimetric/volumetric measurements. By our recently developed “controllable reactive milling device”, we have the unique possibility to perform “in situ” kinetic and thermodynamic analysis under high energy milling conditions in vacuum, hydrogen or borane atmosphere. For the decomposition reaction we focus on the thermal desorption of tetrahydroborates monitored by thermal mass spectrometry. In addition we will analyze the influence of additives known for promoting the decomposition of diborane.
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