1995 Volume 21 Issue 6 Pages 1127-1132
The reaction of p-chlorotoluene over HY, H-mordenite and HZSM-5 zeolites was carried out in a fixed-bed type flow reactor to elucidate the effect of catalyst deactivation on the selectivity of the product. The main products of the reaction were chlorobenzene and m-chlorotoluene over HY and HZSM-5 zeolite, respectively. The difference in the coke production rates between the zeolites was responsible for the selectivity difference. The catalytic activity and m-chlorotoluene selectivity for the reaction over HZSM-5 zeolite decreased with process time, despite the low coke formation rate. The reduction of micropore size by coke deposition on the HZSM-5 zeolite caused a decrease in the catalytic acitivity and m-chlorotoluene selectivity. This interpretation was supported by the reaction of o-chlorotoluene over the same zeolite.
The catalytic activity and the surface area of the spent zeolites decreased with process time due to catalyst deactivation. The deactivation coefficient of HZSM-5 calculated from the relationship between rate constant and process time decreased with reaction temperature. These results suggest that the selectivity for PCT reaction was dependent on the kind of zeolite.