Catalytic dehydrogenation of formic acid

Hydrogen of biogenic origin is a promising alternative to fossil fuels. Within the BMBF project the dehydrogenation of biomass-derived formic acid is utilized as an efficient method for hydrogen production. The concept offers the advantage of spatial and temporal decoupling of biomass utilization and hydrogen production. A wide variety of catalyst systems, both homogeneous and heterogeneous, can be used for the dehydrogenation of formic acid. However, heterogeneous catalysts enable a simple catalyst separation in a technical application, even with high water contents of the aqueous formic acid.

Developing a suitable supported catalyst system for a continuous dehydrogenation process as gas and liquid phase reaction is the primary objective. In addition to a high activity, a high catalytic stability is required in the continuous process. Due to poisoning of the active centers or leaching of catalytically active material, there is a risk of decrease in activity. Consequently, catalyst development is focused on achieving long-term stability to ensure constant activity at continuous dehydrogenation processes. For example, palladium-based catalysts or copper-based materials are possible catalytically active species. To enhance stability, foreign elements like phosphorus can be incorporated in the catalyst system. Phosphorus modification leads to increased CO tolerance, limiting consequently catalyst poisoning.

In addition to catalyst modification, a reactivation process is integrated into the technical process in order to counteract catalyst deactivation. Treatment with atmospheric oxygen restores the poisoned catalyst to its original activity. In a technical application the continuous dehydrogenation of formic acid alternates automatic with oxygen-based reactivation cycles.