A comparative assessment of biofuel products from rice husk and oil palm empty fruit bunch obtained from conventional and microwave pyrolysis

Abstract

• This work is significance as sustainable alternative energy from biomass waste. • MP produced bio-oil with high monoaromatic and phenolic compound and low PAH. • High reaction temperature favour the production of biogas due to intensified secondary reactions. • A remarkable increase in syngas formation when reacted using MP in contrast to CP. Pyrolysis is an alternative heating method developed to produce bio-oil, biogas, and biochar from biomass, including oil palm empty fruit bunch (EFB) and rice husk (RH) pellets. This work focused on the comparison of the products obtained from microwave pyrolysis (MP) and conventional pyrolysis (CP). The experimental work was carried out using MP and CP at 500 °C and 800 °C. The properties of biochars produced from these reactions were characterized. The biofuels were characterized using FTIR and GC-MS, while the biogas was measured using GC-TCD. The composition of the H 2 gas or syngas was also analyzed. MP improved the yield of bio-oil and biochar, but the percentage of biogas yield decreased. The yield of bio-oil produced from the MP of RH and EFB pellets reacted at 800 °C increased significantly from 12.2 to 20.6 wt.% and 15.5 to 20.2 wt.%, respectively. The bio-oil derived from MP has a high content of monoaromatics and phenolic compounds compared to the oil produced from CP. Meanwhile, the bio-oil derived from CP contained a significant amount of polycyclic aromatic hydrocarbons. Although the yield of biogas produced via MP was slightly lower than CP, the total syngas produced from MP was significantly high for both EFB (78 vol.%) and RH (70 vol.%). For CP, only 62 vol.% and 68 vol.% of syngas was produced using EFB and RH, respectively. The findings highlight the potential of MP technology to synthesize environmentally-friendly bio-oil and biogas with a high percentage of syngas. Graphical Abstract .