Preparation of nanoporous carbon particles and their cryogenic hydrogen storage capacities

Spherical nanoporous carbon particles were synthesized from carbon precursor solutions of sucrose with either silica sols or colloidal silica particles, or both, in a direct one-step aerosol-assisted process followed by carbonization and then removal of the silica template. The resulting carbon particles show very high porosity with narrow pore size distributions, surface areas up to 2000 m(2)/g, and pore volumes up to 4.0 cm(3)/g. Three different kinds of spherical nanoporous carbon particles were prepared: (1) unimodal nanoporous particles using tetraethyl orthosilicate (TEOS) as the only silica source for the template, (2) bimodal nanoporous particles using both TEOS and colloidal silica nanoparticles as a composite template, and (3) foamlike highly porous particles using only colloidal silica for the template. The porosity and pore sizes for these carbon particles depend on the type and amount of silica template precursor added to the sucrose precursor solutions. These carbon particles were characterized by transmission electron microscopy, field emission scanning electron microscopy, and nitrogen sorption surface area measurements, and we measured hydrogen adsorption at various temperatures and pressures. Hydrogen sorption of > 4.0 wt % at 77 K and > 20 bar was found for the unimodal nanoporous carbon particles.