Lamellar ZrO2-supported Ni-Fe catalysts for sulfur-free lipid upgrading toward renewable diesel

Developing sulfur-free non-noble-metal catalysts that can selectively regulate hydrogenation, deoxygenation, and C-C bond cleavage is essential for upgrading lipid-derived feedstocks into renewable diesel. Herein, a hydrothermally derived lamellar ZrO 2 support was constructed to tailor the interfacial structure and surface chemistry of Ni-Fe catalysts for fatty acid hydrotreatment. Compared with conventional precipitation-derived ZrO 2 , the lamellar ZrO 2 support induced a t-ZrO 2 -rich phase, higher surface area, slit-like mesoporosity, enhanced acidity, oxygen-vacancy-associated Zr sites, and stronger Ni-Fe-ZrO 2 interactions. These features created more accessible metal-oxide interfacial sites for the adsorption and transformation of oxygenated intermediates. At 240 °C and 2.0 MPa H 2 , Ni-Fe/ZrO 2 -H achieved 86.0% fatty acid conversion, substantially higher than conventional Ni-Fe/ZrO 2 , while suppressing cracking to only 0.4%. The dominant formation of fatty alcohols revealed that the lamellar catalyst preferentially accelerated the hydrogenation and partial deoxygenation of fatty acid-derived intermediates under mild conditions, whereas complete C-O bond cleavage to alkanes remained kinetically limited. Response-surface-assisted analysis further demonstrated that H 2 pressure mainly enhanced fatty acid conversion by improving hydrogen availability, while reaction temperature governed fatty alcohol consumption and diesel-range alkane formation. This work clarifies how hydrothermal support engineering regulates Ni-Fe/ZrO 2 interfacial chemistry and provides a rational strategy for designing sulfur-free catalysts for lipid upgrading.