The Effect of Y-zeolite Acidity on m-Xylene Transformation Reactions

m-Xylene transformation has been studied on as-prepared H-Y and a series of dealuminated Y zeolite catalysts. The conversion of m-xylene was found to increase initially with acidity, however, decreases subsequently. It has been proposed that the high concentration of acid sites in the H-Y catalyst increases paring reaction, in addition to the well-known isomerization and disproportionation pathways. A significant decrease was observed with respect to disproportionation/paring (D/Pa) ratio versus reaction temperature. This indicates that higher activation energy is required for paring as compared to disproportionation reaction. The p-xylene/o-xylene (P/O) was established to be independent of zeolite acidity. A higher coke deposition was found for the transformation of m-xylene over the parent H-Y as compared to the highly dealuminated USY zeolite. The formation of benzene and C2 C4 gases were found to be proportional to zeolite acid concentration.