Preparation and applications of hierarchical porous carbons from direct coal liquefaction residue

Hierarchical porous carbons (HPCs) were prepared from direct coal liquefaction residue (CLR) by KOH activation with addition of silica or silicate. Based on the template role of the mineral salts formed during the KOH activation process, the obtained HPCs have both mesopores and micropores. Several series of samples with different preparation conditions, such as different silica sources, additive dosages, washing procedures after carbonization and additional KOH for the additive in the activation process, were prepared and characterized. The results show that the microporosity of the carbons can increase by more than 28% owing to the addition of silica or silicate, along with the ratio of mesoporosity to microporosity being close to 1:1. Compared with the CLR-based carbon from traditional KOH activation, HPCs with appropriate preparation conditions have improved catalytic performance for catalytic methane decomposition and higher capacitances for supercapacitors. (C) 2012 Elsevier Ltd. All rights reserved.