Using granular activated carbon prepared from oil palm shell by ZnCl2 and physical activation for methane adsorption

Granular activated carbons for methane adsorption have been prepared by impregnation of oil palm shell with various solutions of ZnCl2 followed by heat treatment at 500 °C under a flow of nitrogen. For this precursor, large micropore volume of micropores (with a very small volume of mesopores and macropores) was obtained with intermediate ZnCl2 mass ratio. Methane capacity at 800 mmHg was in the range of 10–12 cm3/g. All the samples were further activated by reaction under a flow of carbon dioxide. Although such activation resulted in a decrease in the BET surface area, average pore width, micropore and pore volume (except very low impregnation ratio, XZn = 0.15 g/g), however, there was a 100% net increase in the methane capacity.