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Keywords:

  • ZSM5;
  • monoliths;
  • toluene disproportionation;
  • para-xylene selectivity;
  • modeling

Abstract

ZSM5 washcoated monoliths with zeolite loading ranging from 10 to 60 wt % were prepared, characterized, and examined for disproportionation of toluene. Toluene conversion increased with temperature and W/FAo but decreased with washcoat thickness. The selectivity of the most desirable isomer (p-xylene) increased with a decrease in temperature, W/FAo and washcoat thickness. The high selectivity to p-xylene indicates that the initially formed para isomer is easily removed from the zeolite pores in the thin washcoat to the bulk gas phase preventing further isomerization of the primary product. A reaction scheme has been proposed for this reaction and the kinetic parameters determined for the 10 wt % ZSM5 monolith. A one-dimensional reactor model was developed to predict the performance of the reactor for disproportionation of toluene. The model equations were coupled with a module to calculate the concentration profile in the washcoat by considering the effect of diffusion and reaction. © 2011 American Institute of Chemical Engineers AIChE J, 00: 000–000, 2011