Preparation of coconut shell-based activated carbon for separation and enrichment of ventilation air methane

The activated carbon was prepared by steam activation, with coconut shells as the raw material, phenolic resin as the binder and polyethylene glycol (PEG) as the pore-making agent and dispersant. Then it was used as the adsorbent in the separation and enrichment of ventilation air methane (VAM) by vacuum pressure swing adsorption (VPSA). The porous properties of activated carbon under different activation parameters and the efficiency of the enrichment of VAM under different VPSA conditions were systematically investigated. The results showed that the precursor of activated carbon was a molding carbon made of phenolic resin and powdered carbon with the mass ratio of 0.5 g/g. If the activate carbon was prepared under such operation conditions with the activation time of 5 h, the flow rate of water of 1.96 cm³/min and the activation temperature of 825 ℃, its specific surface area, micropore volume and micropore ratio would be 795 m²/g, 0.37 cm³/g and 84.1%, respectively. With such activated carbon as the adsorbent, under the optimum operation conditions, CH₄ concentration in the gas production increased from 0.52 vol. % up to 1.51 vol. % and its recovery rate reached about 96% after the enrichment of VAM.