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.
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