Simple fabrication of molecular sieving carbon for biogas upgrading via a temperature controlled carbonization of Phyllostachys pubescens

In this study, molecular sieving carbons (MSCs) for biogas upgrading were successfully fabricated by a simple temperature controlled carbonization of moso bamboo (Phyllostachys pubescens) without energy consuming steps (i.e. char activation and pore modification). As the carbonization temperature increased from 600 to 900 °C, the specific surface area of bamboo charcoals increased and the pore size distribution of bamboo charcoal became narrower and closer to the dimensions of CH4 (0.38 nm). Bamboo charcoals had a more disordered carbon stacking structure than commercial MSC and contained more surface oxides, which contribute to greater surface reactivity than commercial activated carbon. Bamboo charcoal carbonized at 900 °C had the highest CO2 adsorption capacity (121.6 g kg−1), even higher than commercial MSC (102.88 g kg−1). Despite the poor kinetic CO2 adsorption properties of bamboo charcoals compared to commercial MSC, synthetic biogas (60% CH4 + 40% CO2) was successfully upgraded to concentrated CH4 (>90%) by small-scale pressure swing adsorption using bamboo charcoal. It is expected that bamboo charcoals can contribute to sustainable small-scale biogas upgrading.