Zeolite-catalyzed chlorination of toluene by sulfuryl chloride: Activity, selectivity and deactivation of NaX and NaY zeolites

Chlorination of toluene with sulfuryl chloride was studied using NaX and NaY zeolites as catalysts under conditions where ring chlorination predominates. The zeolites are more selective than conventional Lewis acid catalysts with initial para-chlorotoluene : ortho-chlorotoluene ratios of 1.2. Both faujasites studied underwent rapid deactivation under reaction conditions. The deactivation of NaX was much more rapid than that of NaY. The accumulation of polychlorinated toluenes in the pores of the catalyst may be initially responsible for the loss of activity. In the case of NaY, this lost activity can be partially recovered by soaking the catalyst in fresh toluene, whereas attempts to regenerate by burning out the deposited materials cause a rapid disintegration of the catalyst. Zeolite fouling is accompanied by a more severe dealumination process that eventually leads to structural collapse and complete loss of activity.