Efficient and stable Cu-Ni/ZrO₂ catalysts for in situ hydrogenation and deoxygenation of oleic acid into heptadecane using methanol as a hydrogen donor

In this work, a series of ZrO₂-supported Cu, Ni and bimetallic Cu-Ni catalysts were synthesized and evaluated for their activity and stability in the in situ hydrogenation and decarboxylation of oleic acid using methanol as a hydrogen donor. High-angle annular dark-field scanning transmission electron microscopy (HADDF-STEM), energy dispersive X-ray spectroscopy (EDS-mapping), X-ray diffraction (XRD) and temperature programmed reduction (TPR) characterizations revealed that the as-synthesized Cu-Ni/ZrO₂ was a Cu-Ni alloy that was highly dispersed on mixed m-ZrO₂ and t-ZrO₂. The bimetallic Cu-Ni/ZrO₂ nanostructures not only exhibited better catalytic activity for the conversion of oleic acid compared to monometallic Cu/ZrO₂ and Ni/ZrO₂ catalysts but also demonstrated good reuse performance. The formation of the Cu-Ni alloy facilitated the decarboxylation reaction and inhibited the cracking reaction, leading to enhanced catalytic performance. The good stability of Cu-Ni/ZrO₂ was primarily due to the good hydrothermal stability of the ZrO₂ support.