This study was carried out on catalyst A (Dˆ53%) at 5008C under normal pressure. The TPO curves reported in Fig. 1 (curves (1)±(4)) show that the peak corresponding to the coke oxidized at low temperature reaches a level which remains practically constant as a function of time of coking. On the other hand, the amount of coke grows on the metallic sites responsible for the second TPO peak (at ca. 4008C) and on the support (near 5508C) as the reaction time increases