Development of an Iridium-Based Catalyst for High-Pressure Evolution of Hydrogen from Formic Acid

• Published in: ChemSusChem Vol. 9; no. 19; pp. 2749 - 2753
• Main Authors: Iguchi, Masayuki, Himeda, Yuichiro, Manaka, Yuichi, Kawanami, Hajime
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 06.10.2016; Wiley Subscription Services, Inc; John Wiley and Sons Inc
• Subjects: Catalysis; Catalysts; Communication; Communications; Dehydrogenation; Evolution; Filtration; Formates - chemistry; Formic acid; high pressure; hydrogen; Hydrogen - chemistry; iridium; Iridium - chemistry; Ligands; Pressure; Purification; Solubility; formic acid; iridium; catalysis; hydrogen; high pressure
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201600697

A highly efficient and recyclable Ir catalyst bearing a 4,7‐dihydroxy‐1,10‐phenanthroline ligand was developed for the evolution of high‐pressure H2 gas (>100 MPa), and a large amount of atmospheric pressure H2 gas (>120 L), over a long term (3.5 months). The reaction proceeds through the dehydrogenation of highly concentrated aqueous formic acid (FA, 40 vol %, 10 mol L−1) at 80 °C using 1 μmol of catalyst, and a turnover number (TON) of 5 000 000 was calculated. The Ir catalyst precipitated after the reaction owing to its pH‐dependent solubility in water, and 94 mol % was recovered by filtration. Thus, it can be treated and recycled like a heterogeneous catalyst. The catalyst was successfully recycled over 10 times for highpressure FA dehydrogenation at 22 MPa without any treatment or purification. Robust recycle: A highly durable and recyclable Ir catalyst containing a 4,7‐dihydroxy‐1,10‐phenanthroline ligand was developed for high‐pressure gas evolution under 100 MPa by dehydrogenation of formic acid. Simple filtration can recover 94 % of the catalyst after the reaction and it can be successfully recycled over 10 times without deactivation.