Kinetic modeling of heavy reformate conversion into xylenes over mordenite-ZSM5 based catalysts

Conversion of commercial heavy reformate into xylenes is investigated in a fluidized-bed batch reactor to develop a kinetic model. H-mordenite and H-ZSMS based catalysts containing equal amounts of H-mordenite and H-ZSM-5 (SiO2/Al2O3 ratio: 27) were used. The SiO2/Al2O3 ratio of H-mordenite in the catalysts was 18 and 180, which are named as MLZ and MHZ, respectively. The MLZ catalyst resulted in higher conversion of methylethylbenzenes (MEBs) and trimethylbenzenes (TMBs) and exhibited better selectivity toward xylenes due to higher acid-site concentration. Kinetic modeling was carried out using a simplified reaction network which includes: (i) dealkylation of MEBs; (ii) disproportionation of TMBs; (iii) transalkylation of TMBs with toluene; and (iv) paring reaction of tetramethylbenzenes. The results of the mathematical model closely match the experimental data, based on statistically significant estimate of the kinetic parameters, which indicates that the set of assumptions made for kinetic modeling are valid. The order of apparent activation energies, E-paring >> E-dealkylation = E-disproportionation > E-transalkylation, can be ascribed size of the reactant molecules involved in these reactions. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.