Influence of pyrolysis conditions on pore development of oil-palm-shell activated carbons

Oil-palm shells were used to prepare activated carbons. The shells were first subjected to a pyrolysis process and the resulting chars were then treated under a physical activation process in the presence of carbon dioxide. The influences of the operating pyrolysis parameters on the activated carbon were investigated in particular. These parameters included the pyrolysis temperature and hold time, the volume flow rate of the purging gas (N2) and the process heating rate. All the chars were subjected to fixed activation conditions, i.e., CO2 activated at 900 °C, 30 min hold time, CO2 flow rate of 100 cm3/min and heating rate of 10 °C/min under a nitrogen flow rate of 150 cm3/min. Proximate analyses were conducted to determine the constituents of the activated carbons while surface area and porosimetry were carried out to evaluate their pore characteristics. The specific pore surface area and the micropore volume of the activated carbon were used as the criteria for selecting the optimum pyrolysis parameters. The optimum conditions for pyrolysis were a temperature of 600 °C, hold time of 2 h, nitrogen flow rate of 150 cm3/min and heating rate of 10 °C/min.