Microporosity Development in Carbons for Gas-Storage Applications

Gas storage by adsorption on activated carbon is possible at relatively low pressures using activated carbons with a well-developed microporosity. Microporosity is desirable due to the presence of stronger carbon-adsorbate interactions within small pores, which leads to a higher gas-storage density expressed in grams of adsorbed gas per unit of sorbent weight. Another important consideration is the degree of sorbent packing within the storage container. To achieve maximum volumetric storage density, the voidage in the container needs to be minimized. Although some amount of voidage is desirable to ensure good gas transport within the sorbent-filled container, the 30-40% voidage typical of randomly packed sorbent particles is excessive. Thus, an ideal gas-storage system would consist of a nearly 100% microporous sorbent in the form of tightly packed, shaped elements, e.g., discs 5-10 mm in thickness.