Continuous Hydrogen Generation from Formic Acid: Highly Active and Stable Ruthenium Catalysts

The ruthenium-catalyzed decomposition of formic acid was investigated with respect to continuous hydrogen generation and long-term stability of the catalytic systems. A highly active and stable system is presented, which was studied in batch and continuous modes for up to two months. The optimized catalyst system containing N,N-dimethyl-n-hexylamine with an in situ generated catalyst from (benzene)ruthenium dichloride dimer [RuCl2 (benzene)](2) and 6 equivalents of 1,2-bis(diphenyl-phosphino)ethane (dppe) reached at room temperature a total turnover number (TON) of approximatly 260,000 with average turnover frequency (TOF) of about 900 h(-1). Only hydrogen and carbon dioxide were detected in the produced gas mixture which makes this system applicable for direct use in fuel cells.