Influence of operating conditions on pyrolysis of oil palm mesocarp fibre biomass for sustainable biochar production and energy recovery

This research advances circular bio-economy principles in the oil palm agro-industry by valorising oil palm mesocarp fibre (MF-Raw) into biochar and energy carriers from biosyngas and bio-oil. Predicting pyrolysis outputs remains challenging as outcomes depend strongly on feedstock properties and operational parameters. A slow pyrolysis process of MF-Raw was investigated in a laboratory-scale batch tubular reactor using a fractional factorial design of experiments (DoE) to evaluate the influence of key process parameters including temperature (300, 500, 700 °C), N 2 flow rate (0.5, 0.75, 1 SLPM), heating rate (5, 10, 15 °C min −1 ), residence time (30, 60, 90 min), and particle size (granulated 0.13–2 mm; pellet 8 mm). Their interactions on biochar properties were analysed, while also examining the mass and energy potentials of biosyngas and bio-oil. Temperature (A) was the dominant factor across all measured responses, followed by the significant interactions between temperature and N 2 flow (AB), and N 2 flow and heating rate (BC), whereas the individual effects of heating rate (C) and particle size (E) were not statistically significant. Self-energised MF pyrolysis was theoretically feasible at all the tested temperatures, with 500–700 °C giving the best energy surplus (13.75–14.71 MJ kg −1 ) together with the highest product yields. Biochar produced at 500 and 700 °C exhibited H/C and VM/FC ratios below 0.4, indicating high stability with a long-term carbon sequestration potential. These findings highlight a strong suitability of MF-derived biochar for industrial applications in oil palm plantations, thereby potentially to contribute to the decarbonisation of Colombian agro-industrial sectors. • Fractional factorial design identified temperature–N 2 and N 2 –heating rate interactions controlling pyrolysis outcomes. • Temperature showed the strongest statistical individual effect on yields, energy distribution, and biochar composition. • Heating rate and particle size had no significant effect on MF slow pyrolysis in a lab-scale tube reactor. • Energy self-sufficient pyrolysis is theoretically feasible at 500–700 °C based on HHV-derived energy balances. • Stable MF biochar produced (H/C < 0.4; VM/FC < 0.4).