Beschreibung
The world transitions toward sustainable energy sources. In this context, hydrogen plays a key role.$^{[1]}$ Efficient storage and release of hydrogen are essential for its practical application in various fields, including fuel cells and transportable energy storage systems.$^{[2]}$ Here, energy transport and storage via liquid organic hydrogen carrier (LOHC) systems is a significant vector.$^{[3]}$ Notable LOHC systems include toluene/methylcyclohexane and dibenzyltoluene (H0-DBT)/perhydro dibenzyltoluene (H18-DBT).$^{[4]}$ Understanding the diffusion behavior of this hydrogen storage molecules is critical for optimizing materials and systems to enhance performance, safety, and cost-effectiveness.$^{[5]}$
We investigate the diffusion of the LOHC molecule dibenzyltoluene (DBT) and of water in porous monoliths by neutron radiography. The technique leverages the fact that the neutron absorption cross section of hydrogen is approximately 1000 times greater than that of deuterium (D or $^{2}$H).$^{[6]}$ The resulting contrast in radiographic imaging allows for the observation of time-dependent concentration profiles arising from self-diffusion of the molecules within a monolith. The process is induced by controllably bringing the deuterated liquid in contact with a non-deuterated liquid ensuring an initially sharp boundary at a well-defined starting point.
Preliminary results will be presented. We anticipate that this method will enable fast, straightforward, and accurate determination of the diffusion of hydrogen carrier molecules in porous systems of different pore size and surface chemistry, providing novel insights into the transport mechanisms of LOHCs. Additionally, this method will be explored to measure the surface-, bulk- and wetting dynamics of LOHCs in porous systems.
[1] B. Pivovar et al., Electrochem. Soc. Interface 27, 47 (2018).
[2] A. Saberi Mehr et al., Int. J. Hydrogen Energy 70, 786-815 (2024).
[3] H. Jorschick et al., Int. J. Hydrogen Energy 45, 29,14897-14906 (2020).
[4] T. Rüde et al., Sustainable Energy Fuels 6, 1541-1553 (2022).
[5] K. Koizumi et al., Phys. Chem. Chem. Phys. 21, 7756-7764 (2019).
[6] V.F. Sears, Neutron News 3, 29 (1992).
