Investigation of (complex) hydrides as hydrogen storage systems using calorific methods
In the course of the global energy transition, i.e. the switch from fossil fuels to renewable energy sources, concepts for reversible energy storage are needed to compensate for fluctuations in the output of environmentally friendly energy sources that are only available intermittently. One variant currently being discussed is the chemical storage of hydrogen using complex hydrides such as NaAlH4:
3 NaAlH4 ↔ Na3AlH6 + 2 Al + 3 H2 ↔ NaH + 3 Al + 4.5 H2
Hydrogen is to be stored by hydrogenating the decomposition products of the complex hydride and released again through its thermal decomposition.
A large number of these hydrides can be produced by metathesis reactions. The synthesis is carried out either in solution or mechanochemically in a ball mill.
The aim of research at the Institute of Physical Chemistry with regard to complex hydrides and other related compounds is to carry out fundamental investigations into their suitability and optimisation for reversible hydrogen storage. With regard to mobile applications, the development of hydrides for the high-pressure range is of particular interest. For this purpose, various complex hydrides and mixtures of these are thermodynamically characterised with regard to their dehydrogenation and hydrogenation behaviour. This is mainly done using thermogravimetry coupled with dynamic differential scanning calorimetry and decomposition gas analysis (TG-DSC-FTIR/MS), with DSC measurements under high hydrogen pressure (HP-DSC, see Fig. 1) and by recording pressure-composition isotherms with a Sieverts apparatus (see Fig. 2).
The investigation of complex hydrides using TG-DSC primarily serves to elucidate the dehydrogenation reactions.
The influence of the hydrogen pressure on the hydrogenation and dehydrogenation temperatures and the reversibility of the reactions as well as cycle stabilities can be studied on the basis of the HP-DSC measurements. Furthermore, statements and data on the thermodynamics and kinetics of the processes taking place can be derived.
The reversible hydrogen storage capacity and the equilibrium pressures of the hydrogenation-dehydrogenation cycles investigated at different temperatures can be determined by recording pressure-composition isotherms. This can also be used to determine the thermodynamic data of the reactions.
Topics for graduate theses:
For interested students, topics for student research projects, bachelor's and master's theses/dissertations can be arranged individually on an ongoing basis.
Selected publications:
Publications in journals:
F. Habermann, K. Burkmann, B. Hansel, B. Störr, C. Schimpf, J. Seidel, M. Bertau, F. Mertens, "Hydrogen absorption and desorption in the V-Al-H system", Dalton Trans. 2023, 52, 4880-4890, https://doi.org/10.1039/D2DT03718A
F. Taubert, D. Thomas, R. Hüttl, J. Seidel, F. Mertens, "Experimental determination of enthalpies of formation of Li17Si4, Li16.42Si4 and Li13Si4" ,J. Alloys Compd. 2022, 897, 163147-163155, https://doi.org/10.1016/j.jallcom.2021.163147
L. Sandig-Predzymirska, J. Ortmeyer, J. Wagler, E. Brendler, F. Habermann, M. Anders, M. Felderhoff, F. Mertens, "The direct and reversible hydrogenation of activated aluminium supported by piperidine" Dalton Trans. 2020, 49, 17689-17698, doi.org/10.1039/D0DT03175E
J. Ortmeyer, A. Bodach, L. Sandig-Predzymirska, B. Zibrowius, F. Mertens, M. Felderhoff, "Direct Hydrogenation of Aluminum via Stabilisation with Triethylenediamine: A Mechanochemical Approach to Synthesise the Triethylenediamine ⋅ AlH3 Adduct", Chemphyschem 2019, 20, 1360-1368, doi.org/10.1002/cphc.201801093
D. Thomas, N. Bette, F. Taubert, R. Hüttl, J. Seidel, F. Mertens, "Experimental determination oft he enthalpies of formation oft he lithium silicides Li7Si3 and Li12Si7 based on hydrogen sorption measurements", J. Alloys Compd. 2017, 704, 398-405, doi.org/10.1016/j.jallcom.2017.02.010
Conference contributions:
F. Habermann, K. Burkmann, B. Störr, J. Seidel, K. Bohmhammel, F. Mertens, "Study of the Influence of NaCl and LiCl on the Decomposition of Sr(AlH4)2", The 25th Calorimetry Days, Braunschweig 2023, pdf download
K. Burkmann, F. Habermann, J. Kraus, E. Schumann, B. Störr, J. Seidel, K. Bohmhammel, J. Kortus, F. Mertens, "Thermodynamic Study of Zirconium and Hafnium Boranate - Zr(BH4)4 and Hf(BH4)4", Die 25. Kalorimetrietage, Braunschweig 2023, pdf-Download
L. Sandig-Predzymirska, K. Burkmann, J. Seidel, F. Mertens, "Influence of the aluminium addition on the hydrogenation/dehydrogenation behaviour of doped sodium alanate" Die 23. Kalorimetrietage, Braunschweig 2019, pdf download
Contact
- Prof. Dr Florian Mertens (Florian [dot] Mertens [at] chemie [dot] tu-freiberg [dot] de (email))
- Dr Jürgen Seidel (Juergen [dot] Seidel [at] chemie [dot] tu-freiberg [dot] de (email))
- M. Sc. Franziska Habermann (franziska [dot] habermann [at] chemie [dot] tu-freiberg [dot] de (email))
- Dipl.-Chem. Konrad Burkmann (Konrad-Joerg [dot] Burkmann [at] chemie [dot] tu-freiberg [dot] de (email))
