Synergistic Co–Ni Alloy Enables Efficient Fatty Acid Transfer Hydrodeoxygenation via Dual-Site-Driven Tandem Catalysis

Hydrodeoxygenation (HDO) is crucial for producing lipid-based jet fuels but faces challenges like harsh conditions and reliance on fossil-derived hydrogen. Herein, a Ni-based CoAl-layered double oxide (Ni/CoAl-LDO) bimetallic catalyst with highly dispersed Co–Ni alloy was synthesized via a successive hydrothermal-impregnation strategy for efficient transfer HDO of fatty acids under mild temperatures without pressurized H2. Notably, this catalyst achieved 94.5% alkane yield and 1.47 mmol/gmetal/h alkane productivity at 230 °C (isopropanol as H-donor/solvent), outperforming monometallic CoAl-LDO (0.134 mmol/gmetal/h) and NiAl-LDO (0.233 mmol/gmetal/h) by factors of 10.8 and 6.3 in productivity, respectively. Moreover, this catalyst demonstrated excellent stability in continuous transfer HDO of stearic acid and versatility in processing diverse fatty acids of different chain lengths. Kinetic studies indicated that Co promoted fatty acid HDO to octadecanol, while Ni promoted the dehydrogenation and decarbonylation of octadecanol to heptadecane. This Co–Ni synergy significantly enhanced catalytic efficiency. This work provides valuable insights into the rational design of an efficient catalyst for the hydrogen-free, mild synthesis of oil-based jet fuels.