Highly Efficient Reversible Hydrogenation of Carbon Dioxide to Formates Using a Ruthenium PNP‐Pincer Catalyst

Abstract

The use of hydrogen as a fuel requires both safe and robust technologies for its storage and transportation. Formic acid (FA) produced by the catalytic hydrogenation of CO2 is recognized as a potential intermediate H2 carrier. Herein, we present the development of a formate‐based H2 storage system that employs a Ru PNP‐pincer catalyst. The high stability of this system allows cyclic operation with an exceptionally fast loading and liberation of H2. Kinetic studies highlight the crucial role of the base promoter, which controls the rate‐determining step in FA dehydrogenation and defines the total H2 capacity attainable from the hydrogenation of CO2. The reported findings show promise for the development of practical technologies that use formic acid as a hydrogen carrier.

Highly Robust Hydrogen Generation by Bioinspired Ir Complexes for Dehydrogenation of Formic Acid in Water: Experimental and Theoretical Mechanistic Investigations at Different pH

“…In some cases, the hydrogen storage capability (i.e., reversible interconversion between CO 2 and FA) can be achieved using the same catalyst by changing reaction conditions such as pressure, temperature, and pH. [10][11][12][13][14][15][16][17] Various heterogeneous and homogeneous catalysts for FA dehydrogenation have been reported. [6][7][8]18 Despite recent important progress, [19][20][21][22] heterogeneous catalysts often suffer from low activity and selectivity (including the generation of CO that poisons fuel cell catalysts).…”

“…[34][35][36] Pincer complexes with non-innocent ligands have also shown outstanding catalytic activity in FA dehydrogenation in organic solvents. 10,28,37 Inspired by the active center of [Fe]-hydrogenase (Scheme 1c), 38,39 we have designed and synthesized a series of proton-responsive complexes (Scheme 1d) for efficient catalytic interconversion of formic acid/formate and H 2 /CO 2 in 4 water. 14,[40][41][42] The bipyridine or bipyrimidine ligands bearing pendent OH groups are redox noninnocent, proton-responsive, and act as cooperating ligands which have been demonstrated to be largely responsible for the high activity of the complexes.…”

Iridium Catalysts with Diazole-containing Ligands for Hydrogen Generation by Formic Acid Dehydrogenation

“…Enhancement of the catalytic activity was also observed with the N-methylated biimidazole complex 12 (Entry 19). The N _ H bond in the imidazole moiety as a ligand is essential for hydrogen-bond formation between the NH group and FA in FA dehydrogenation in an organic solvent 17) , but the protons of the N _ H moieties of the ligand in 10 may not be involved in the catalytic cycle in this aqueous reaction. Presumably the water solvent in our catalytic system prevented the formation of a hydrogen bond.…”

The role of Ir4 cluster in enhancing the adsorption of CO2 on selected zeolites – GCMC simulations

“…The approach that is the most interesting from both academic and industrial point of view, is the chemical conversion of the CO 2 into valuable chemicals or energy carriers [5]. However, due to high thermodynamical stability of the CO 2 molecule, highly active catalysts to be developed [1,2,6].…”