Isomerization of m-Xylene without Side Reactions, over a Perfluorinated Polymer Sulfonic Acid. A Kinetic Study

A solid superacidic catalyst was obtained from the corresponding potassium salt (Nafion-K) and employed for studying the m-xylene isomerization in a fixed bed flow reactor. Temperature ranged from 143 to 173°C. A mixture of m-xylene with toluene, trimethylbenzenes, and 1,2,4,5-tetramethylbenzene, in ratios closely approaching the overall equilibrium between polymethylbenzene fractions, was fed in a nitrogen stream. Disproportionation reactions were thus avoided, a clean isomerization of m- to o- and p-xylene observed, and its kinetics measured. Since the catalyst deactivates, checks of its decreasing activity were performed at intervals and a correction of kinetic measurements devised, in order to evaluate the rate coefficients for a fresh catalyst.