Ni‐Doped CeO ₂ as Ceramic Catalyst for Gamhar Sawdust Pyrolysis: Product Distribution and Enriched Bio‐Oil Production

ABSTRACT The current study investigated the effect of Ni‐CeO 2 catalysts on the product distribution and bio‐oil enrichment during catalytic upgrading of gamhar sawdust (GS) pyrolysis. Structural characterization of Ni‐CeO 2 catalysts confirmed CeO 2 lattice retained the cubic fluorite structure. The average crystallite size was ∼43 nm, and XPS analysis confirmed defect redistribution. Catalyst addition showed a remarkably positive effect on both bio‐oil yield and optimum temperature. Optimum bio‐oil yield for thermal pyrolysis was determined to be 41.07 wt% at 600°C, while the bio‐oil yield increased to 47.80 wt% at 550°C in the case of 10 wt% Ni/CeO 2 ‐assisted pyrolysis. Furthermore, catalytic bio‐oil showed superior properties to the thermal pyrolysis‐derived bio‐oil. GC–MS and FTIR confirmed that catalytic upgrading redirected the bio‐oil selectivity from oxygen‐rich furans and carbonyl compounds to more aromatic hydrocarbons and partially deoxygenated phenolics. Unlike thermal pyrolysis, the catalytic process reduced the oxygenated functionalities and changed the pathways of vapor‐phase cracking, without major structural collapse of ceria support. BET surface area of solid residue was further estimated as 393 m 2 /g at 700°C, Overall, tuned oxygen vacancies and surface redox properties of Ni‐CeO 2 have successfully modulated the devolatilization chemistry and selective vapor upgrading during GS pyrolysis.