Attrition of catalyst particles in a laboratory-scale fluidized-bed reactor

Attrition of fluid catalytic cracking catalysts is investigated in a laboratory scale fluidized bed. It is shown that the catalyst attrition arises from a mixed mechanism of particle fragmentation and surface abrasion. The measured conventional attrition rate always decreases with time, even for a long-time attrition; therefore, a relative attrition rate is suggested. Experiments indicate that after a nonsteady-state attrition where the measured relative attrition rate decreases with time, the attrition gets into a steady state and the measured relative attrition rate Lends to a constant value. Furthermore, the Lime-dependence of particle attrition is discussed. It is seen that the widely-used Gwyn equation cannot model the catalyst attrition accurately. Alternatively, an exponential decay attrition model is proposed and confirmed to describe the Lime-dependent attrition behavior, It is found that the model parameters have definite meanings and are strongly related to the particle properties, fluidization conditions and fluidized bed structure. (C) 2015 Elsevier Ltd. All rights reserved,