DEACTIVATION KINETIC-MODEL IN CATALYTIC POLYMERIZATIONS - TAKING INTOACCOUNT THE INITIATION STEP

A kinetic model based on the postulates of Langmuir-Hinshelwood has be en proposed for the catalyst deactivation by coke in heterogeneous pol ymerizations. The originality of the model lies in the fact that deact ivation is also taken into account during the initiation period by def ining the activity as the useful fraction of active sites throughout t he polymerization. The validity of the proposed deactivation kinetic m odel has been shown for the polymerization of gaseous benzyl alcohol i n an ample range of operating conditions: catalysts (silica/aluminas a nd a HY zeolite) with different acidity and different porous structure , temperature, and monomer concentration. The results are compared wit h those of the previously defined model, where activity referred to th e maximum polymerization rate.