Scaled-up reactor for microwave induced pyrolysis of oil palm shell

•A bench-scale microwave (MW) reactor was designed and constructed.•The design with two magnetrons was based on FEM simulations.•The dual magnetrons inducing standing waves were superior to single magnetron.•Activated carbon and oil palm shells had synergistic MW absorption.•During MW induced pyrolysis the 400 g mixture batches reached 700 °C temperatures.

We designed and implemented bench-scale equipment for the microwave pyrolysis of biomass, and tested its effects on oil palm shell (OPS). The design uses the interference of two MW sources to increase the electric field intensity, based on model predictions by finite elements simulations. The MW pyrolysis experiments were done varying the mixture ratio of OPS and activated carbon (75:25, 50:50, or 25:75 by weight), the MW power (450 or 800 W), and the use of MW source magnetrons (left, right, or both). The pyrolysis temperature depended on the varied experimental parameters. The highest temperature and the highest yields of liquid bio-oil and gas were obtained with the 75:25 mixture treated with 800 W total power using both magnetrons. The end-products were analyzed with bomb calorimeter, GC–MS, and the solid residue with SEM. The results demonstrate that the bench-scale equipment is suited for experimental work on the pyrolysis of biomass (OPS).