A more precise classification of the micropores would distinguish two types of micropores, narrow and wide pores [10]:

• ultramicropores: pore size <0.7 nm

• supermicropores: pore size in the range of 0.7-2.0 nm

Micropores in porous carbons are very important for gas adsorption because their quantity and size are closely related to the specific surface area and the interaction with adsor-bates. As a consequence of the overlapping of the adsorption potential of opposite pore walls, the filling of the microporosity corresponds to the initial steep portion of the

Table 1. Classification of pore.

1. Classification by size (see text)

Ultramicropore <0.7 nm Supermicropore 0.7-2.0 nm

2. Classification by origin

• Intraparticle pore: existing in crystallites

Intrinsic pore: originated from crystal structure Extrinsic pore: induced by doping of foreign substances

• Interparticle pore: generating by aggregation of primary particles

Rigid pore Flexible pore

3. Classification by pore situation

• Open pore: accessible to adsorbates

• Latent pore: open, but very narrow so as to be inaccessible to adsorbates

• Closed pore: isolated from surface and inaccessible to adsorbates

Source: Reprinted with permission from [16], M. Inagaki and K. Kaneko, in "Commentary on Carbon Family—Variety and Evaluation" (M. Inagaki, Ed.), p. 156. Agune Syoufuu Sha, Tokyo, 2001. © 2001, Agune Syoufuu Sha Publishing.

adsorption isotherm at low relative pressure. The classification of adsorption isotherm curves will be explained in detail in Section 2.3.1.

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