Thermal liquefaction of olive tree pruning waste into bio-oil in water and ethanol with NaOH catalyst

In this study the effect of catalysts and solvents at varying temperatures on the production of bio-oil from olive tree pruning waste (OPW). The thermal liquefaction process was conducted at 200degree celsius, 225degree celsius, and 250 degree celsius for 90 min, employing either water or ethanol as solvents, with alkaline catalysts (0.125 M, 0.25 M, and 0.5 M NaOH) introduced for the first time. Raw material, solid byproducts, and bio-oil samples underwent FTIR analysis for structural changes, TGA for proximate analysis, and GC-MS for bio-oil analysis. Results revealed that NaOH enhanced biomass conversion in water, yet didn't increase bio-oil yield, whereas in ethanol, biomass conversion was relatively lower, but bio-oil yield improved despite the adverse effects of catalyst. The highest biomass conversion (94 %) was achieved at 250degree celsius with 0.5 M NaOH, but the maximum bio-oil yield (25 %) occurred without a catalyst in water. Conversely, the highest bio-oil yield (55 %) was attained using ethanol without a catalyst at 250degree celsius.