Acidity Regulation of Ni-Fe/ZSM-5 Catalysts for Enhanced Lipids Deoxygenation toward Renewable Diesel Production

Abstract

Catalytic deoxygenation of lipids provides a sustainable route for producing renewable diesel-range hydrocarbons. Herein, Ni-Fe/ZSM-5 catalysts with different Si/Al molar ratios were fabricated to unravel the correlation between catalyst acidity and lipid deoxygenation performance. Comprehensive characterizations confirmed that tuning the Si/Al ratio could precisely regulate the acidity, metal dispersion and textural properties of the catalysts, which significantly dominated the catalytic activity and product selectivity. Notable, the Ni-Fe/ZSM-5 catalyst with a Si/Al ratio of 25 achieved the best activity and maximum selectivity toward diesel-range alkanes. The appropriate acid site density and highly dispersed Ni-Fe bimetallic sites facilitated the hydrodeoxygenation (HDO) pathway and simultaneously inhibited undesired cracking reactions. Additionally, the Ni-Fe synergistic effect effectively improved catalytic stability. This study validates that acidity tuning of ZSM-5 supports is an effective strategy to enhance lipid deoxygenation, and provides fundamental insights for the rational design of high-performance catalysts for sustainable conversion of lipids biomass into renewable diesel.