A semi-embedded Ni@ZSM-5 catalyst for efficient fatty acid hydrodeoxygenation: the role of metal–support interactions

Abstract

Deoxygenation of biomass-derived fatty acids presents an effective and sustainable pathway for producing diesel-range alkanes. However, achieving hydrodeoxygenation (HDO) under relatively mild conditions while effectively mitigating carbon deposition remains challenging. Herein, we report a semi-embedded Ni@ZSM-5 catalyst synthesized via an acetic acid sodium-assisted hydrothermal strategy, which features smaller Ni nanoparticles and enhanced metal–support interactions. Ni@ZSM-5 exhibited excellent HDO performance for palmitic acid under mild conditions (240 °C, 2 MPa of H₂, 4 h), achieving 99% conversion and 99% selectivity towards C₁₅ + C₁₆ alkanes, with a C_n/C_n−1 ratio of 2.5. These results indicate favorable catalytic performance compared with those of previously reported systems. A poisoning experiment combined with density functional theory (DFT) calculations revealed that synergy between metal and acidic sites plays a crucial role: Ni nanoparticles efficiently dissociate hydrogen and activate the substrate, while the acidic sites facilitate C–O bond cleavage. More importantly, the unique semi-embedded structure of Ni@ZSM-5 significantly inhibits Ni sintering, thereby enhancing anti-coking capability and stability. This study provides a feasible strategy for improving the anti-coking performance of catalysts in biodiesel production.