The oxidn. of an amorphous carbon black in the presence of a potassium-copper-vanadium catalyst supported on -alumina was studied. Burn-off temps. in the presence of catalyst were lowered by .apprx.300 K with respect to those for un catalyzed combustion. Cycles of temp.-programmed redn. and oxidn., along with TG-MS analyses demonstrated that a redox mechanism is at the basis of the catalyst strong activity. A differential flow reactor was employed to perform kinetic tests. The progress of the catalytic combustion process was followed measuring the concns. of carbon oxides in the product stream at the reactor outlet with online NDIR analyzers. The dependence of the reaction rate on the relevant variables was investigated. In particular, the apparent activation energy for the catalytic oxidn. was less than half that of the corresponding uncatalyzed process, while the carbon reactivity showed a linear dependence upon the amt. of catalyst and a square root dependence upon the oxygen partial pressure. The results allowed the formulation of a mechanism for the catalytic oxidn. of carbon black and suggest that the limiting step of the overall process is that of catalyst redn. On the basis of such findings a kinetic equation for catalytic carbon black oxidn. is proposed.
Catalytic oxidation of an amorphous carbon black
CIAMBELLI, Paolo;D'AMORE, Matteo;PALMA, Vincenzo;VACCARO, Salvatore
1994-01-01
Abstract
The oxidn. of an amorphous carbon black in the presence of a potassium-copper-vanadium catalyst supported on -alumina was studied. Burn-off temps. in the presence of catalyst were lowered by .apprx.300 K with respect to those for un catalyzed combustion. Cycles of temp.-programmed redn. and oxidn., along with TG-MS analyses demonstrated that a redox mechanism is at the basis of the catalyst strong activity. A differential flow reactor was employed to perform kinetic tests. The progress of the catalytic combustion process was followed measuring the concns. of carbon oxides in the product stream at the reactor outlet with online NDIR analyzers. The dependence of the reaction rate on the relevant variables was investigated. In particular, the apparent activation energy for the catalytic oxidn. was less than half that of the corresponding uncatalyzed process, while the carbon reactivity showed a linear dependence upon the amt. of catalyst and a square root dependence upon the oxygen partial pressure. The results allowed the formulation of a mechanism for the catalytic oxidn. of carbon black and suggest that the limiting step of the overall process is that of catalyst redn. On the basis of such findings a kinetic equation for catalytic carbon black oxidn. is proposed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
