Recent Advances in Catalytic Transfer Hydrogenation with Formic Acid over Heterogeneous Transition Metal Catalysts

Transition-metal-catalyzed transfer hydrogenation with an in situ hydrogen donor has received a great deal of attention from both academia and industry as an alternative to the traditional high-pressure-hydrogen process, owing to its better efficiency, atom economy, and sustainability features. Hydrogen stored in the chemical bonds of formic acid (FA), a promising hydrogen storage compound that could be derived from biomass or reduction of CO₂, can be extracted selectively and used for diverse catalytic transformations. This Review summarizes and compares recent progress in catalytic transfer hydrogenation (CTH) via heterogeneous hydrogen transfer from FA. Transformations of biomass-derived platform chemicals (e.g., aromatic units, C5 and C6 sugars, furans, glycerol, fatty acids, levulinic acid (LA)), nitrogen-containing compounds (e.g., nitroarenes, quinolines), and organochlorinated compounds via transfer hydrogenation, hydrogenolysis, and hydrodechlorination (HDC) are outlined. Synthesis strategies of the heterogeneous metal catalysts (e.g., metal and support type, metal-support interaction, single-atom, alloy effect, and confinement effect) and optimization of the reaction conditions (e.g., temperature, solvents, additives, and FA dosages) for enhancing the catalytic activity and regulating the product distribution are presented. Structure-activity relationships based on both dehydrogenation and hydrogenation of metal catalysts as well as the mechanistic interpretation of CTH with FA are also highlighted. Finally, current challenges and outlook for the future development of the field are discussed. © 2021 American Chemical Society. All rights reserved.