Iron-Catalyzed Hydrogen Production from Formic Acid

Abstract

Hydrogen represents a clean energy source, which can be efficiently used in fuel cells generating electricity with water as the only byproduct. However, hydrogen generation from renewables under mild conditions and efficient hydrogen storage in a safe and reversible manner constitute important challenges. In this respect formic acid (HCO(2)H) represents a convenient hydrogen storage material, because it is one of the major products from biomass and can undergo selective decomposition to hydrogen and carbon dioxide in the presence of suitable catalysts. Here, the first light-driven iron-based catalytic system for hydrogen generation from formic acid is reported. By application of a catalyst formed in situ from inexpensive Fe(3)(CO)(12), 2,2':6'2''-terpyridine or 1,10-phenanthroline, and triphenylphosphine, hydrogen generation is possible under visible light irradiation and ambient temperature. Depending on the kind of N-ligands significant catalyst turnover numbers (>100) and turnover frequencies (up to 200 h(-1)) are observed, which are the highest known to date for nonprecious metal catalyzed hydrogen generation from formic acid. NMR, IR studies, and DFT calculations of iron complexes, which are formed under reaction conditions, confirm that PPh(3) plays an active role in the catalytic cycle and that N-ligands enhance the stability of the system. It is shown that the reaction mechanism includes iron hydride species which are generated exclusively under irradiation with visible light.

Improved hydrogen generation from formic acid

“…[5] Applying a catalyst formed in situ from inexpensive Fe3(CO)12, 2,2':6'2''-terpyridine and triphenylphosphine hydrogen generation is possible under visible light irradiation and ambient temperature. Applying 1,10-phenanthroline as Nligand significant catalyst turnover numbers (>100) are observed, which is the highest activity known to date for non-precious metal catalyzed hydrogen generation from formic acid.…”

Biomass oxidation to formic acid in aqueous media using polyoxometalate catalysts – boosting FA selectivity by in-situ extraction

“…6 More recently, FA has been proposed as a suitable hydrogen storage compound because it can be easily and selectively decomposed to hydrogen and CO 2 through metal catalysed processes under very mild conditions. [7][8][9][10] It should be noted that by thermal decomposition (above 373 K), FA can also be converted into CO and water. Thus, FA can be regarded as a liquid syngas equivalent.…”

Single Isolated Pd2+ Cations Supported on N-Doped Carbon as Active Sites for Hydrogen Production from Formic Acid Decomposition

“…[48][49][50] These complexes were used as homogeneous catalysts for different reactions. Thus, recently it was shown that complexes of some noble metals 51 and iron 52 with phenanthroline type ligands are active in conversion of CO 2 to formate species 51 and in dehydrogenation of formic acid. 52 Generally, the activity of homogeneous catalysts based on metal complexes is higher in formic acid dehydrogenation than that of heterogeneous catalysts containing metal nanoparticles.…”