Engineering of the N-doped carbon support for improved performance of supported Pd catalysts in hydrogen production from gas-phase formic acid

Abstract

Development of N-doped Pd/C catalysts for hydrogen production from gas-phase formic acid is a challenge. To elucidate the efficient routes of nitrogen insertion on the surface of a mesoporous carbon support, the latter was treated with melamine (Mel), dicyandiamide or NH3 at 673 and 823 K. Pyrolysis of the melamine/carbon mixture taken in a 1:2 ratio provides an increase in the reaction rate by a factor of 5. The inserted N-sites strongly interact with Pd leading to the formation of highly dispersed Pd nanoparticles (∼1.6 nm) and active atomically dispersed Pd2+ species. With a further increase of the Mel/C ratio, the number of surface N-sites decreases due to occupation of carbon support pores with a g–C3N4–type residue. This provides a decrease in the Pd dispersion leading to lower reaction rates. Therefore, melamine is an efficient N precursor. The considered synthesis of N-doped catalysts could be scaled.