Synthesis of Mesoporous Carbons from Bituminous Coal Tar Pitch Using Combined Nanosilica Template and KOH Activation

Mesoporous carbons (MCs) facilitate mass transport in pore networks and enhance the performance of porous carbon. By combining a nanosilica template with KOH activation, highly porous MCs with BET specific surface areas (SBET) greater than 1000 m2/g were synthesized from unmodified commercial coal tar pitch. The MCs had a honeycomblike morphology with randomly arranged macropores. An increase in template amount resulted in an increase in pores larger than 20 nm, the size of silica template. An MC sample activated at 850 °C for 2 h with a KOH-to-carbon ratio of 2.7:1 and a pitch-to-template ratio of 3:1 had an SBET value of 1366 m2/g, 65 vol % mesopores, 19 vol % macropores, and an average pore diameter of 25 nm. Whereas the silica template was largely responsible for macropores and large mesopores, KOH created new micropores and enlarged existing pores through KOH–carbon reactions. Moreover, KOH enhanced the formation of carbonyl, carboxyl, and lactonic groups on the carbon surface. The feasibility of synthesizing MCs from an unmodified commercial carbon precursor with a simpler route was demonstrated.