Porosity development along the synthesis of carbons from metal carbides

Carbide derived carbons (CDCs) are materials containing a wide range of pore size, their properties and applications being a function of the pore structure. For this reason it is important to find the relationship between synthesis parameters, such as initial carbide and temperature, and resulting structure. In this work, CDCs were prepared from VC, TiC, WC, TaC, NbC, HfC and ZrC at different temperatures and they have been characterized by means of gas adsorption. Nitrogen at −196 °C and carbon dioxide at 0 °C adsorptions were used to obtain structural information such as apparent surface area (SBET), micropore volume (Vmicro) and pore size distribution (PSD). These studies show that these parameters vary strongly depending on synthesis temperature (700–1200 °C) and initial carbide. Since the size of micropores is near the range suggested as being ideal for methane (CH4) storage, the high-pressure methane adsorption at 25 °C was performed to check the possible use of CDCs as storage material. The CH4 adsorption capacity of CDCs can compete with other carbons on a gravimetric basis, though the volumetric one is far from desired due to their low packing density.