Optimal Single-Walled Carbon Nanotube Vessels for Short-Term Reversible Storage of Carbon Dioxide at Ambient Temperatures

Optimized light vessels composed of single-walled carbon nanotubes have high gravimetric and volumetric capacity for short-term reversible storage of CO2 at 298 K and near-ambient operating pressures. We use grand canonical Monte Carlo simulation for modeling of CO2 adsorption at 298 K and pressures up to 5.7 MPa. It is shown that both gravimetric and volumetric uptake of CO2 strongly depend on the pore size in nanotubes but not on their chiral vector. Moreover, for any operating storage pressure, a unique optimal size of carbon nanotubes is well-defined. At 1.5 MPa, the most efficient nanotubes that maximize both gravimetric and volumetric uptake of CO2 (i.e., 13.6 mmol g-1 and 11.4 mol dm-3) have diameters of 3.8 nm. This size corresponds to the (28,28) armchair nanotubes.