Densification of ordered microporous carbons and controlling their micropore size by hot-pressing

Ordered microporous carbons synthesized by the template method using zeolite Y were hot-pressed at 573 K up to 147 MPa, aiming at densification of the templated carbons for the future use as energy storage media. Upon the hot-pressing, the powdery templated carbons were easily pelletized without any binder and the bulk density was significantly increased from 0.2 g/cm³ to 0.7-0.9 g/cm³. As a result, both the surface area and micropore volume per unit volume were increased. Surprisingly, it was found that the hot-pressing treatment reduced the average micropore size and it was tunable by simply adjusting a pressure in the treatment. In contrast, such changes in the density and the pore structure were not observed for commercial KOH-activated carbons when they were hot-pressed under the same conditions. The observed peculiar behavior of the templated carbons upon the hot-pressing can be explained by their unique molecular structure as compared to the conventional activated carbons.