Quantitative aqueous phase formic acid dehydrogenation using iron(II) based catalysts

- Formic acid is a safe and easy to handle liquid phase hydrogen source.
- H2 can be generated in aqueous solution under mild conditions.
- For the first time aqueous Fe(II) catalyst is used for the selective H2 production.

We present here the results of our investigation on aqueous phase formic acid (FA) dehydrogenation using non-noble metal based pre-catalysts. This required the synthesis of m-trisulfonated-tris[2-(diphenylphosphino)ethyl]phosphine sodium salt (PP3TS) as a water soluble polydentate ligand. New catalysts, particularly those with iron(II), were formed in situ and produced H2 and CO2 from aqueous FA solutions, requiring no organic co-solvents, bases or any additives. Manometry, multinuclear NMR and FT-IR techniques were used to follow the dehydrogenation reactions, calculate kinetic parameters, and analyze the gas mixtures for purity. The catalysts are entirely selective and the gaseous products are free from CO contamination. To the best of our knowledge, these represent the first examples of first row transition metal based catalysts that dehydrogenate quantitatively formic acid in aqueous solution.

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