Hierarchical porous honeycomb NiCo/C catalyst for decarboxylation of fatty acids and upgrading of sludge bio-crude

Honeycomb NiCo/C-Na catalyst featured with a micro-meso-macroporous structure is fabricated and shows a significantly higher catalytic activity for decarboxylation of fatty acid compared to a series of other carbon-based catalysts. A 100 % conversion of stearic acid and a C15-18 alkane total yield of 70 % is achieved at 280 °C for 3 h under 1 MPa H₂ with heptadecane as the main product. NiCo/C-Na also achieves a complete conversion of monoglyceride into heptadecane when using edible oil as reactant. The catalyst is further evaluated for upgrading of sludge HTL bio-crude and proves to be highly efficient. The obtained upgraded biofuel exhibits a decreased viscosity and an increased density. Specifically, the higher heating value (HHV) increases to 47.32 MJ/kg. This result is attributed to the easier desorption of CO₂, better H₂ activation capacity and the unique hierarchical pore structure of the catalyst, which allows faster mass transfer and reaction rate.