Stable Al2O3 washcoat on additively manufactured 316L monoliths for ethanol steam reforming and hydrogen production

Abstract

Additive manufacturing enables metallic structured catalysts with tailored geometry, but stable ceramic washcoats on metallic monoliths remain a challenge under ethanol steam reforming (ESR) conditions. Here, selective-laser-melted 316L monoliths were pretreated by thermal and chemical routes, coated with $\gamma$-Al₂O₃, impregnated with Ni, and evaluated under thermal cycling to 600 °C and ESR. SEM/EDS showed that printing-induced surface features, including partially fused particles, pores, and staircasing, promoted mechanical anchoring of the washcoat. After 10 thermal cycles, untreated monoliths retained 93.8% of the alumina, while all pretreated samples remained above 95%. Under ESR, the bare 316L monolith showed moderate activity, whereas the Ni/$\gamma$-Al₂O₃/316L monolith achieved near-complete ethanol conversion from 425 °C, higher H₂ selectivity, and lower intermediate formation. This combination of structural design, surface engineering, and catalytic functionality positions additively manufactured metallic monoliths as promising structured catalysts for distributed hydrogen production from renewable ethanol.