Effects of the heating history of impregnated lignocellulosic material on pore development during phosphoric acid activation

Activated carbon samples have been prepared by heating China fir (Cunninghamia lanceolata) wood impregnated with phosphoric acid in an effort to elucidate the effect of the heating history of impregnated material on the porous texture of the activated carbon. Analysis of the pore structure of the activated carbon in terms of nitrogen adsorption isotherms showed that both using an intermediate isothermal treatment and slowing the heating rate up to 300 °C favor pore development but have a detrimental effect above 300 °C. Therefore, it is recommended that a two-step heating program is applied for phosphoric acid activation.