Extraction of bio-oil during pyrolysis of locally sourced palm kernel shells: Effect of process parameters

The aim of this study was to determine the effect of particle size, pyrolysis temperature and residence time on the pyrolysis of locally sourced palm kernel shells and to characterize the bio-oil products. Pyrolysis experiments were performed at pyrolysis temperatures between 350 °C and 550 °C and particles sizes of 1.18 mm, 2.36 mm and 5 mm for a residence time not greater than 120 min. The maximum bio-oil yield was 38.67 wt% at 450 °C for a feed particle size of 1.18 mm with a residence time of 95 min. It was observed that the percentage of liquid collection was 28% of the total biomass feed for particle size of 1.18 mm. In terms of the effect of temperature, the lowest bio-oil yield was 28% of the total biomass feed at temperature of 550 °C. For the variation in residence time and the associated effects, the maximum liquid product was 38.67 wt% of biomass feed, at a particle size of 1.18 mm for 95 min. As observed, the optimum residence time was 95 min as times either side led to a decrease in the liquid yield. The bio-oil products were analysed by Fourier Transform Infra-Red Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS). The FTIR analysis showed that the bio-oil was dominated by phenol and its derivatives. The phenol (38.44%), 2-methoxy-phenol (17.34%) and 2, 6-dimethoxy phenol (8.65%) that were identified by GC-MS analyses are highly suitable for extraction from bio-oil as value-added chemicals. The highly oxygenated oils can therefore be upgraded in order to be used in other applications such as transportation fuels.