Over the past decades, the hydrogenation of CO₂ to more valuable products such as formic acid or methanol has been highly emphasized in the academic field because of the continuous increase of CO₂ in the earth’s atmosphere. The challenge of converting CO₂ results mainly from its considerable Gibbs free energy (ΔG° = -394.4 kJ/mol). Therefore active co-reactants and/or catalysts are usually needed. Formic acid, one of the CO₂ hydrogenation derivatives, is an efficient hydrogen carrier and has great potential to be applied in fuel cells. Nowadays various efficient homogeneous catalytic systems have been developed to convert CO₂ to formic acid, such as the iridium complexes with PNP pincer-type^1,2 and bipyridine-type ligands³ or⁴ ruthenium complexes with N-heterocyclic carbenes.⁴ However, the above-mentioned homogeneous catalysts were only applied in batch reactors, which are less favored in industrial continuous processes, and efficient well-defined immobilized catalysts are still sparse in CO₂ hydrogenation. Here, we aim at synthesizing new immobilized catalysts, which are supported on well-defined silica-based hybrid materials or synthetic polymers, and applying them in a continuous CO₂ hydrogenation process.

[1] Tanaka, R.; Yamashita, M.; Nozaki, K. Journal of the American Chemical Society 2009, 131, 14168.
[2] Tanaka, R.; Yamashita, M.; Chung, L. W.; Morokuma, K.; Nozaki, K. Organometallics 2011, 30, 6742.
[3] Hull, J. F.; Himeda, Y.; Wang, W.-H.; Hashiguchi, B.; Periana, R.; Szalda, D. J.; Muckerman, J. T.; Fujita, E. Nat Chem 2012, 4, 383.
[4] Filonenko, G. A.; Smykowski, D.; Szyja, B. M.; Li, G.; Szczygieł, J.; Hensen, E. J. M.; Pidko, E. A. ACS Catalysis 2015, 5, 1145.