Influence of compressing pressure on macro void formation of carbon monolith for methane adsorption

Carbon monoliths for adsorbed natural gas (ANG) storage were prepared from Mongolian anthracite-based activated carbons using carboxy-methyl cellulose as a binder under different compressing pressures. Nitrogen adsorption/desorption experiments were carried out to obtain the specific surface area, pore volume, and pore size distribution of the monoliths. Methane adsorption experiments on the carbon monoliths were conducted at different temperatures and pressures up to around 3.5 MPa in a high pressure volumetric adsorption apparatus. As expected, adsorption results indicated that the methane adsorption capacity of the carbon monoliths increased with increasing specific surface area and packing density. The maximum volumetric adsorption of methane was observed as 163 V/V at 293 K and 3.5 MPa on a carbon monolith sample, PMAC1/2-3-65, that does not have the highest specific surface area but relatively high packing density comparing with other monoliths, which implies that two physical properties contribute contradictorily to the methane adsorption capacity. Based on experimental results, the carbon monoliths prepared from Mongolian anthracite-based activated carbons can be promising media for ANG storage application