Exploiting The HCOOH/CO2 Cycle For Hydrogen Production And Storage By Homogeneous Catalysis

In the quest for sustainable routes to efficient hydrogen production and storage, liquid organic hydrogen carriers (LOHC) are nowadays considered as promising materials for this purpose. Among them, formic acid (FA, 4.4 % wt) affords H2 + CO2 gas mixtures by dehydrogenation in an "atom efficient" process. The CO2 (or bicarbonate) by-product can be re-hydrogenated back to FA (or formate), affording a zero-carbon footprint cycle for hydrogen storage and release. Among the methods to deliver such reactions, homogeneous catalysts based on precious and non-precious transition metal complexes have shown remarkable activities and are currently studied by many research groups worldwide. In the past few years, our Research Unit at CNR-ICCOM has developed efficient catalytic processes for both FA dehydrogenation and NaHCO3 hydrogenation based on Ru-water soluble phosphines, Ru(II) and Fe(II) polydentate phosphine complexes working under mild conditions of pressure and temperature. An overview of principal results, including mechanistic studies, will be here presented.