| comprehensive kinetic study on the influences of cations introduced and their concentration on coke reactivity during regeneration in oxygen-containing gases was undertaken. It is found that coke reactivity is independent of coke loading for both H-form and cation-exchanged zeolite-Y catalysts. However, coke reactivity strongly depends on the type of introduced cations and their concentration. A significant difference in coke reactivity, of up to three orders of magnitude, is observed when cation type changes from potassium to copper. It is of interest to note that coke reactivity even increases exponentially with increasing cation concentration for all studied cations. The sensitivity of coke reactivity to cation concentration is found to change significantly from one cation to another. The order of sensitivity for the studied cations was determined to be: ;For comparison, char gasification with and without cations was carried out under same conditions. It is observed that there are substantial similarities in kinetics (such as the activation energy, pre-exponential factor and the reaction order with respect to oxygen) between catalyzed char gasification and catalyst regeneration. However, the effectiveness of cations in char gasification, with the order of... |
