Steam Gasification of Biochar Obtained from Oil Palm Empty Fruit Bunches Using Peridotite as Catalytic Bed Material

Oil palm empty fruit bunch (OPEFB) is considered a recalcitrant agricultural waste due to the hard-to-digest structure of lignin. In this study, peridotite, a waste rock from the mining industry, was valorized as a suitable and cheap bed material for the gasification of OPEFB biochar. Besides, the effectiveness of three kinetic models on the representation of gasification was investigated. The gasification experiments were carried out in a stainless-steel fixed bed reactor at three temperatures: 700◦C, 760◦C, and 830◦C, using sand and calcined peridotite as bed materials. The experimental data were fitted using three kinetic models: volume reaction model (VRM), grain model (GM), and random pore model (RPM). The calcination of peridotite caused structural and surface changes in the material, such as sintering and the formation of ????-Fe2O3 and forsterite (Mg2SiO4). The maximum biochar conversions were higher with peridotite in comparison to sand. The predictive capacity of the tested models followed this order: RPM>VRM>GM. The activation energies (Ea) obtained with all models were lower for the gasifications with peridotite. The results proved a significant catalytic effect of peridotite for the OPEFB gasification in comparison to sand.