Estimation of Rate Parameters in Reaction Rate Equations for Catalytic Caracking of Butane in View of Catalyst Deactivation

Abstract

In order to take the progress of deactivation into consideration in the rate equations derived in the previous paper, the cracking of butane over a silica-alumina catalyst in a tubular flow reactor was investigated at 600°C, under atomosperic pressure and with feed rates of butane of 16 to 59 m//min. Particular attention was paid to the changes of the amount and the atomic ratios of hydrogen to carbon of coke (Figs.1 and 2) and the distributions of gaseous products (Figs.3 and 4) as a function of process time.
The stoichiometric equations derived in the previous paper were modified by introducing the two-step reactions of coke formation which could explain the observed decrease in the H/C ratios in coke with increasing process time (Table 1). By solving simultaneously the rate eqUations (Eq. ( 1 ) ) and the process equations containing the position of reactor and the process time as the variables by Marquardt method, the rate parameters were obtained (Table 2). These values explain satisfactorily the changes in coke formation and gaseous product distributions with process time.