In-situ potassium hydroxide catalysis improves bio-oil composition and bone-char quality during pyrolysis of chicken meat-bone waste.

The poultry industry generates significant amounts of chicken meat-bone waste (MBW). This study analysed the MBW pyrolysis products and evaluated the effects of potassium hydroxide (KOH) as a catalyst. Both untreated and KOH-impregnated MBW were pyrolysed at 400-800 °C. KOH addition increased biochar and gas yields but reduced bio-oil yield, and significantly improved bio-oil quality by reducing the yield of oxygenated and nitrogenous compounds. At 500 °C, KOH addition reduced the production of oxygenated compounds, mostly acids, in bio-oil by 85 % compared to non-catalysed pyrolysis. It also enhanced diesel-range hydrocarbons (C10-C19) production by 40 % and decreased production of monoaromatic hydrocarbons of the gasoline-range (C5 - C12). Bone chars were alkaline and rich in phosphorus (8-14 wt%), potassium (1-13 wt%), and calcium (15-19 wt%), with phosphorus contents comparable to or exceeding rock phosphate and single superphosphate fertilisers. KOH catalyst further enhanced water-soluble contents of P (15-fold) and K (20-fold). These findings highlight the potential of KOH-impregnated MBW pyrolysis for sustainable waste management and high-value biochar and bio-oil production.