Ruthenium Clusters on Carbon Nanofibers for Formic Acid Decomposition: Effect of Doping the Support with Nitrogen

The catalytic properties of 1wt% Ru catalysts with the same mean Ru cluster size of 1.4-1.5nm supported on herringbone-type carbon nanofibers with different N contents were compared for H-2 production from formic acid decomposition. The Ru catalyst on the support with 6.8wt% N gave a 1.5-2times higher activity for the dehydrogenation reaction (CO2, H-2) than the catalyst on the undoped support. The activity in the dehydration reaction (CO, H2O) was the same. As a result, the selectivity to H-2 increased significantly from 83 to 92% with N-doping, and the activation energies for both reactions were close (55-58kJmol(-1)). The improvement could be explained by the presence of Ru clusters stabilized by pyridinic N located on the open edges of the external surface of the carbon nanofibers. This N may activate formic acid by the formation of an adduct (>NH+HCOO-) followed by its dehydrogenation on the adjacent Ru clusters.