Promoting Hydrodeoxygenation of Inedible Biolipids Via Coking and Sintering Resistant Co-Loaded ZrO2–SiO2 Dual-Support Catalyst

Deoxygenation of various fatty acid methyl esters (FAMEs) and inedible biolipids to diesel-range alkanes was investigated over an efficient dual-supported Co-based catalyst (Co/Zr_n–SiO₂). The combination of SiO₂ and ZrO₂ dual-support improves the catalytic performance and reduces the apparent activation energy of the Co-based catalyst, with three advantages: (i) both the high surface area of SiO₂ and the encapsulating effect of ZrO₂ favor the formation of smaller Co nanoparticles and fine dispersion, which in turn reduces coke deposition; (ii) incorporating oxyphilic Zr increases the content of Co⁰ while also improving the electron density of Co and the ratio of oxygen deficient (O_D), which is favorable for the dissociation of H₂ and adsorption of C=O/C–O bonds; (iii) hydroxyl-rich SiO₂ and abundant ZrO_x−O_D−Co interfaces synergistically promote the hydrodeoxygenation (HDO) and suppress the decarbonylation (–CO)/decarboxylation (–COO) pathways, effectively preventing carbon loss. The Co/Zr_0.25–SiO₂ with 10 wt% Co and 0.25 Zr/Si molar ratio is used for the deoxygenation of methyl palmitate, yielding 97.6% selectivity towards diesel-range alkanes, with 85.1% hexadecane at full MP conversion. Complex inedible biolipids such as jatropha oil and waste cooking oil can be easily transformed into diesel-range alkanes with a selectivity of 93.9% and 91.6%, respectively. Furthermore, the catalyst shows stable recyclability in the current catalytic deoxygenation system.