Sustainable and efficient production of formic acid via additive-free CO2 hydrogenation enabled by amine-functionalized Pd catalysts

Formic acid (FA), an essential industrial feedstock and promising liquid organic hydrogen carrier, is currently predominantly produced via fossil fuel-dependent routes. The hydrogenation of CO 2 to FA offers a sustainable alternative, but prevailing catalytic processes typically rely on non-recyclable alkali additives to overcome thermodynamic limitations, complicating product separation and generating waste. Herein, we report a novel amino-functionalized, hierarchical porous carbon-supported Pd catalyst (Pd/HPC-DETA, where DETA denotes diethylenetriamine) for the alkaline additive-free hydrogenation of CO 2 to FA. This design synergistically integrates a hierarchically porous architecture for efficient mass transfer, amine groups for in situ CO 2 activation, and highly dispersed Pd nanoparticles for H 2 dissociation. The catalyst achieves an apparent turnover number (TON) of 266 and an apparent turnover frequency (TOF) of 33 h −1 , comparable to conventional alkali-assisted systems while demonstrating robust stability. This is a state-of-the-art performance achieved by a heterogeneous catalyst without the use of basic additives under the similar conditions. This work provides a sustainable and scalable strategy for green FA production, paving the way for efficient carbon utilization.