EXPERIMENTAL OPTIMIZATION OF BIO-OIL YIELD FROM COCONUT SHELL PYROLYSIS USING BOX BEHNKEN DESIGN.

Abstract

Pyrolysis of coconut shell for maximum yield of bio- oil in a fixed bed reactor was investigated in this study. Box Behnken design of experiment in the Response Surface Methodology (RSM) was used to investigate the effect of temperature (400, 500 and 600^oC), reaction time (5, 10 and 25 minutes) and feed particle size (6, 9.5 and 13 mm) on the yield of bio-oil. RSM was used to estimate the optimum conditions for maximum yield of bio-oil. Preliminary pyrolysis experiment showed that bio-oil increased with temperature up to 500^oC where it was thermally decomposed into gas and then reduced to minimum. Other pyrolytic products (char and gas) were also significantly influenced by temperature, time and feed particle size. The coefficient of determination (R²) of the model of bio-oil yield in terms of temperature, time and size was 0.9893 at p < 0.05. The maximum bio-oil yield was 47.00% at 486.67 ^oC, 22.78 minutes and 6.78 mm and these was experimentally verified. The pyrolysis oil obtained at these optimum process conditions was analysed using Fourier Transform Infrared Spectroscopy (FTIR) and the oil yield obtained agreed with the predicted value with percentage absolute error of 0.85%.