Thin ZSM-5 film catalysts on quartz and alumina supports

Alumina beads, quartz and soda glass were coated with ZSM-5 films using a seeding method. Films with a thickness of 150, 350, 800 and 2300 nm were prepared. The catalysts were tested by para-xylene (pX) isomerization and triisopropylbenzene (TiPB) cracking. Model parameters, i.e. rate constants and diffusivities, were fitted to experimental results. The films on quartz glass were much more active for pX isomerization and for cracking of TiPB, which was also reflected by the model parameters. Low and zero rate constants for alumina and soda glass supported catalysts, respectively, were attributed to poisoning of the ZSM-5 film due to impurities in these supports. Larger diffusivity in quartz supported catalysts and thick films was attributed to more defects in the film.