Mass and Energy Yields of Bio-oil Obtained by Microwave-induced Pyrolysis of Oil Palm Kernel Shell

Microwave-induced pyrolysis of palm kernel shell was carried out to investigate the effects of microwave power and bed temperature on the mass and energy yields of bio-oil. The conditions were 573 K and 1 kW, 623 K and 1 kW, 573 K and 2 kW, and 623 K and 2 kW. The biomass conversion was enhanced by higher pyrolysis temperature. The target product, i. e. the liquid or so-called bio-oil, consisted of two layers; upper watery and lower oily layers. Higher microwave irradiation power favored higher selectivity towards the lower layer bio-oil. This result implies that higher irradiation enhanced faster heating, thus a higher selectivity towards the lower layer bio-oil. The calorific value and carbon content of bio-oil obtained showed considerable dependency on the bed temperature and microwave power. On the other hand, char properties showed little dependency on the bed temperature and microwave power. The highest overall bio-oil energy yield of 32 % was obtained at 2 kW and 573 K.