(687d) Liquid Organic Hydrogen Carrier and Their Application at Moderate Temperatures

Liquid Organic Hydrogen Carrier (LOHC) are able to store hydrogen in a dense and safe manner under ambient conditions. Hydrogen is fixed by covalent bonds to an organic molecule and can be released catalytically. This dehydrogenation reaction is endothermal and operated at temperatures of around 300 °C. With heteroaromatic systems this temperature would be lower, but several other disadvantages have to be dealt with.

Thermodynamically it is also possible to decrease the dehydrogenation temperature by reducing the hydrogen partial pressure. Yet, the reaction kinetics are still a challenge at moderate temperatures. An ultimate target would be releasing hydrogen at temperatures of around 200 °C. However, alternative catalytic concepts are needed for this operation. This can involve reaction via different types of transferring agent.

If temperature can be lowered, there is a huge potential for increasing energy efficiency. First, providing heat to the release unit is easier and losses to the ambience can be reduced. Second, completely different approaches for providing heat become available. These include utilizing waste heat from power generation units like fuel cell. Thus, the energy demand decreases significantly.

Different concepts for the provision of energy from hydrogen bound to LOHCs will be presented. The focus of the discussion will be on thermodynamics and catalysis of hydrogen release, but also alternative technological options and the application on large scale will be evaluated.

This work is funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy through the project “Emissionsfreier und stark emissionsreduzierter Bahnverkehr auf nicht-elektrifizierten Strecken”.