A study of the kinetics for the liquid phase isomerization of ortho-xylene over H-mordenite has been made at 505OK, 2.76 X lo5 N/m2, and 23 mole *% toluene diluent. This is the first known study reporting kinetic data for the liquid phase isomerization of xylene over a zeolite catalyst. High activity is indicated by the SOTo achievement of para-xylene equilibrium at 505OK, 2.76 X 105 N/m2, and 0.767 X kg/s/kg. Although high selectivity has previously been reported for a specifically prepared zeolite catalyst, the 99+ Yo selectivity of the isomerization reaction with H-mordenite as indicated by no Cg+ aromatics and less than 0.5 mole yo benzene in the product is most significant. Catalyst deactivation was also significant. Reaction rate constants are reported for a first-order reversible triangular model among the xylene isomers with catalyst deactivation incorporated into the model. J. R. HOPPER SCOPEOrtho and para-xylene are important chemical intermediates. New catalysts which offer high activity and selectivity can alter the optimum economic decision for their production. The objective of this study was to establish a kinetic model for xylene isomerization over a zeolite catalyst-H-mordenite. The study was performed under conditions of liquid phase, toluene diluent, and relatively lower temperature (505OK) for which kinetic data have not been previously reported but for which high activity and selectivity were recently demonstrated with an undisclosed zeolite catalyst (Grandio et al., 1971). H-mordenite is known to have high initial activity for this reaction (Hansford and Ward, 1968), but the selectivity is not reported. Catalyst deactivation, if it existed, was to be incorporated into the model. The results of this study can provide further insight into the catalytic properties of Hmordenite and quantitative kinetic information on the magnitude of the activity, selectivity, and catalyst deactivation which are of major value in process optimization and control evaluations. CONCLUSIONS AND SIGNIFICANCEThe isomerization of ortho-xylene over H-mordenite was investigated at 505OK, 2.76 X 105 N/m2 and about 23 mole '% toluene diluent. The most significant observation was the 99+ yo selectivity to the isomerization reaction and no formation of Cg+ aromatics. The activity was very good with an 807' achievement of para-xylene equilibrium at a space velocity of 0.767 X 10-3 kg/s/kg. Catalyst deactivation was significant. The reaction was modeled by the first-order reversible interconversion triangular reaction scheme among the isomers. The catalyst deactivation was correlated by an exponential decay function of the feed/ catalyst ratio. The model in compact notation is expressed as l 6 r . -2 BOk e-ak(e17) R~~ The reaction model constants given in Table 4 show the conversion of ortho to para-xylene occurs primarily by the series of 1, 2 methyl shifts first to meta-xylene and then to para-xylene.Hydrocarbon isomerization reactions have received considerable attention in the past two decades. Significant progress in p...

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