Robust Catalyst for the Dehydrogenation of Formic Acid

Robust Catalyst for the Dehydrogenation of Neat Formic Acid

Elyse Kedzie

According to the U.S. Energy Information Administration (EIA), global energy consumption is projected to grow by 48% by year 2040.¹ This presents a clear obstacle for the worldÕs continued economic growth. The rate of energy consumption is much greater than its production; thus, it is necessary to find new and methodical ways to harvest energy and convert it to portable fuels. In regards to transportation, liquid petroleum is most commonly used to operate our vehicles, which creates sustainability and global carbon balance issues. A developing form of alternative energy is the use of hydrogen. However, because it exists as a gas at ambient temperatures, it has low energy density and some safety risks.

Formic acid (FA) is a promising hydrogen storage material because it is an inexpensive, nontoxic, easily handled liquid.² FA can be converted to CO₂ and H₂, the latter being a clean energy carrier with application in fuel cells in which the byproduct is water. In this research, we investigated iridium complex 1 and showed it to be the first efficient homogeneous catalyst for the decomposition of neat formic acid (FA) into H₂ and CO₂.³ Complex 1 works under mild conditions in the presence of air, is remarkably robust with a turnover number (TON) greater than 2,000,000 (which is more than twice the highest TON previously reported), and is reusable without regeneration. Furthermore, the decomposition reaction proceeds with high selectivity (carbon monoxide, CO, a possible byproduct which poisons fuel cell catalysts) is not produced at a detectable level. 

Figure 1: Iridium Complex 1

This is the first truly practicable, high throughput system for generating H₂ from formic acid for fuel cell applications.

1. ÒEIA projects 48% increase in world energy consumption by 2040Ó. US Energy Information Administration: Independent Statistics and Analysis. 2016.
2. Yamamoto, Y. Chem. Rev. 2012, 112, 4736-4769.
3. Celaje, J. J. A.; Lu, Z.; Kedzie, E. A.; Terrile, N. J.; Lo, J. N.; Williams, T. J. ÒA Prolific Catalyst for Dehydrogenation of Neat Formic AcidÓ Nature Commun. 2016, 7, 11308