Kinetics of catalyst deactivation. An example: methylnaphthalene transformation

The progressive deactivation of various HNaY zeolite catalysts (Si/Al=2.4), during methylnaphthalene isomerisation, was studied at 573-663 K. The acti vity decay was expressed as a function of time-on-stream (t-o-s) and of cok e content (C-c). In both cases very simple exponential equations, whose par ameters depend on the degree of decationation of the zeolite and temperatur e were satisfactorily used to fit the experimental data. Coke analysis was performed on the most acidic catalyst (HNaY-98) at T=633 K and the composit ion of the coke soluble in methylene chloride was determined. The influence of temperature and ion-exchange degree on the coke deposition rate was als o examined. (C) 1999 Elsevier Science B.V. All rights reserved.