Engineering 3D Pd/AC catalysts for the continuous production of hydrogen from formic acid

Formic acid is a liquid organic hydrogen carrier for the safe hydrogen storage and transport. This study presents the fabrication of 3D-printed activated carbon (AC) monoliths by robocasting and their use as supports for Pd-based catalysts in the continuous hydrogen production (25–55 °C, 0.5–1 M FA, τ = 20–540 g CAT h L −1 ). The aim is to identify the optimal internal architecture for process scale-up. While monolith geometry does not alter Pd nanoparticle properties (size ∼ 2.2 nm, dispersion 20–28%, Pd 2+ /Pd 0 = 1), it significantly affects flow behaviour and structural robustness. The optimal design, incorporating a central axial channel, achieves initial TOFs up to 5087 h −1 at 55 °C. After over 100 h of operation, only a 23% activity loss is observed. Kinetic analysis reveals a second-order rate law in FA and 36 kJ mol −1 activation energy. These results demonstrate the potential of engineered 3D Pd/AC monoliths for efficient and scalable hydrogen production. • 3D-printed Pd/AC monoliths fabricated by robocasting for continuous hydrogen production. • Catalyst geometry influenced fluid dynamics, mass transfer and mechanical stability. • Optimized CAT#2 with closely packed square channels and one central large cylindrical channel. • 23 % deactivation after 100 h of operation due to Pd sintering and loss of dispersion. • A kinetic model confirmed FA second-order reaction and accurately predicted hydrogen flow.