The Influence of Oxygen in the Carbonization of Oil Palm Shell on Bio-Char Yield and Properties

The presence of oxygen from air infiltration during the carbonization process of biomass is expected to be detrimental to biochar yield and properties. Experimental study was carried out on oil palm shell in a fixed-bed pyrolyser under various oxygen concentrations ranging from 0% to 11 % by varying the nitrogen and oxygen fractions in the pyrolysing gas mixture. The two critical parameters: the bed temperature and holding time were also varied. Process optimization was carried out by Response Surface Methodology (RSM) by employing Central Composite Design (CCD) using Design Expert 6.0 Software. The effect of oxygen ratio and holding time on biochar yield within the temperature range studied were statistically significant. The optimum condition of 30.0 % biochar yield of palm shell was predicted at pyrolysis temperature of 420 °C, oxygen percentage of 2.3% and holding time of two hours. This prediction closely agreed with the experiment finding of 31.1% biochar yield.