Simultaneous oxidation of carbon black and volatile organic compounds over Ru/CeO2 catalysts

Ru/CeO2 catalysts with Ru loading of 1-5 wt.% were prepared by wet impregnation from aqueous ruthenium (III) nitrosyl nitrate solution and activation with an air flow at 600 degrees C for 4 h. This activation resulted in a considerable reactivity for the catalytic oxidation of carbon black (CB) (T-50%similar to 350 degrees C "tight contact" mixtures and T-50%similar to 515 degrees C "loose contact" mixtures) and volatile organic compounds (VOCs) (T-50%=175 degrees C for propene, T-50%=215 degrees C for toluene). When carbon black oxidation was conducted under "propene (6000 ppm) + air" or "toluene (2000 ppm) + air" flow, the elimination of an important part of CB was observed at relatively low temperatures comparing to its elimination under pure air flow. These temperatures correspond to the total oxidation of the VOC present in the reactant gases. Carbon black total elimination was also investigated under isotherm conditions in the presence and in the absence of propene. Total elimination occurred during shorter times when combustion was performed under propene. TPR study showed that ruthenium species present in the catalysts after activation reduces at relatively low temperatures (< 100 degrees C) and that from a Ru loading of 1.5 wt.%, agglomerated ruthenium oxide was formed and that this latter is more difficult to reduce (> 100 degrees C). (C) 2008 Elsevier B.V. All rights reserved.