CATALYTIC ACTIVITY AND SHAPE SELECTIVITY OF METHYLATION OF TOLUENE OVER HZSM-5 ZEOLITE IN AN INTEGRAL REACTOR

A model was developed for representing the activity and the shape selectivity of HZSM-5 zeolite catalyst in an integral reactor for the methylation of toluene with methanol. This model took account of the catalytic properties, such as the intracrystalline diffusivity, and the acidic properties within and on the outer surface of the zeolite crystallite. These properties were directly measured by methods developed by the authors. Two kinds of HZSM-5 zeolites with different Si/Al ratios were prepared. The methylation of toluene was performed using an integral reactor at 673 to 773 K. The experimental results were found to be well predicted by the proposed model. A chart based on the model is also presented which predicts the influence of the size of the zeolite crystallite and of the acidic properties on shape selectivity in a wide range of the methanol conversions.