One promising possibility for the storage of hydrogen without the drawbacks of other technologies is the conversion of formic acid to hydrogen by means of homogeneous catalysis. Thus it is possible – starting from room temperature – to decompose formic acid into hydrogen and carbon dioxide. The use of formic acid as base material for chemical industry purposes offers the advantage of existing infrastructure for liquid fuels. Additionally, formic acid is only slightly toxic. This leads to a number of advantages in terms of efficiency, compact system design and low emissions for off-grid and mobile applications.
In a recently completed project funded by the Federal Ministry of Economics and Technology ZBT in close cooperation with Leibniz – Institute for Catalysis e.V., Rostock (LIKAT) could prove that a fuel cell can be operated with hydrogen from formic acid decomposition. In such a system formic acid is selectively and almost without the formation of CO decomposed with the support of a ruthenium-based catalyst into hydrogen and carbon dioxide. The resultant gas mixture can be converted in the fuel cell into electricity without further separation. The favourable temperature range of about 60 ° C for the decomposition is provided by the fuel cell’s waste heat via an integrated cooling circuit.
The focus of the project was the identification of appropriate catalytic systems for the selective decomposition of formic acid (LIKAT), development of a reactor system suitable for scaling the decomposition process for higher power ranges (ZBT with LIKAT), adapting the NTPEM fuel cell operating conditions and the thermal coupling of the components to a functional system (ZBT).
The integrated system was fed with formic acid and continuously provided about 65 W of electrical power for several hours. The potential of the use of formic acid as a hydrogen storing material for fuel cells could clearly be demonstrated. In the project the operation as a functional model could be shown. However, a number of additional questions were raised, which led to the previously announced application for a follow-up project.
The final report can be obtained from the applicant Member Association IUTA which summarizes the project results.
