Catalytic characteristics of specialty carbon blacks in decomposition of methane for hydrogen production

Catalytic characteristics of specialty (color and conductive) carbon blacks (CBs) for methane decomposition were investigated and compared with those of rubber blacks. The catalytic characteristics of the color blacks were more similar to those of the rubber blacks, in such that both blacks exhibited very stable activity, a positive correlation of the activity with increasing specific surface area, and higher activation energies. However, the conductive blacks showed quasi-stable behavior, leveling-off of the activity at a somewhat higher value despite their specific surface areas being several times higher than the most active color black, and significantly lower activation energies, These differences were attributed to their morphology differences: the color and rubber blacks were nonporous, whereas the conductive blacks were highly porous. Particularly, the conductive blacks had many dented corners at the pore wall with a highly active armchair structure, resulting in the lower activation energies. Meanwhile, the reaction orders over all the specialty and rubber blacks lay between ca. 0.7 and 1, but no obvious trend in the reaction order was discernible with respect to the surface area or type of CBs. (C) 2008 Elsevier Ltd. All rights reserved.