Carbonization of Synthesized Resins as Means to Control Micropores of Porous Carbon

Four methods were examined to prepare porous carbons with controlled micropores from phenolic resins. Firstmethod carbonizes phenolic resins synthesized from formaldehyde and various phenols. At the carbonization temperatureof 600°C, phenol-resin or 1, 2, 3-trihydroxybenzene-resin had uniform micropores of 0.4 to 0.45nm in diameter, whereas 1, 5-dihydroxynaphthalene-resin had larger micropores of 0.4 to 0.5nm in diameter. The larger pores werefound to be formed through the devolatilization of 1, 5-dihydroxynaphthalene remaining in the resin. This presenteda possibility to control micropores by devolatilizing the substance incorporated in the resin during carbonization.Second method carbonizes resins prepared from the mixture of two different phenols. The mixed resin synthesizedfrom 1, 2, 3-trihydroxybenzene and 1, 5-dihydroxynaphthalene had large micropores of 0.9 to 1.1nm which did notexist in either 1, 2, 3-trihydroxybenzene or 1, 5-dihydroxynaphthalene-resin. This presented a possibility to controlmicropores by carbonizing mixed resins.Third method uses resin of different cross-link densities as starting materials. However, the cross-link densitydid not affect significantly the size of micropores of carbonized resins.Fourth method is to control the carbonization by loading mechanical pressure, and consequently to controlmicropores of carbonized resins. This method was found to be effective to decrease the size of micropores.