Tailoring product distribution during upgrading of palmitic acid over bi-functional metal/zeolite catalysts

•Ni-/Co-H-ZSM-5 enhanced hydrodeoxygenation to decrease hydrodecarbonylation.•Deoxygenation, isomerization and cracking occurred over Ni-/Co-H-ZSM-5 catalysts.•More C16 and iso-products formed over Co-H-ZSM-5 catalysts.•H-ZSM-5 favored hydrodecarbonylation and the direct cracking of palmitic acid.

Bi-functional metal (Ni and Co)/zeolite catalysts were designed to upgrade palmitic acid. No isomerization products were observed over parent zeolitic supports H-ZSM-5 without metal phase, but hydrodeoxygenation (minor route), hydrodecarbonylation (major route) and the direct cracking were observed. On one hand, the impregnation of Ni or Co species, enhanced hydrodeoxygenation via hydration-hygenation route and decreased hydrodecarbonylation route. On the other hand, metal phase decreased the isomerization temperature, which is consistent with enhanced the acidic strength of whole bi-functional catalysts especially for Co/zeolite catalysts. Simultaneous deoxygenation of palmitic acid, isomerization of hydrogenated products and cracking were achieved over bi-functional Ni/H-ZSM-5 and Co/H-ZSM-5 catalysts, with more C16 and iso-products formation. Furthermore, the introduction of mesopores obviously enhanced iso-products and C16 formation for Co-based catalysts.

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