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 path...

Xylenes transformations have been investigated over ZSM-5 zeolite in a riser simulator that mimics closely the operation of commercial fluidized-bed reactors. P-xylene was found to be more reactive than the other isomers followed by o-xylene and m-xylene was found to be least reactive. The order of reactivity is consistent with the order of diffusivity. At low temperature (400°C), isomerization...

The effect of H2 on isomerization pathways and on the acid site density on WOx-ZrO2 catalysts was explored using kinetic measurements of acid-catalyzed o-xylene isomerization reactions. Initial o-xylene isomerization rates on WOx-ZrO2 at 523 K are proportional to the H2 concentration even though H atoms are not involved directly in reaction turnovers, as shown by the low deuterium content in th...

In the present work, the transformation of m-xylene was studied over fresh and pre-coked HZSM-5 catalyst in a riser simulator over the temperature range of 350-500C.Significant differences were observed in both the activity and product selectivity pattern for the two forms of the catalyst. While, the fresh catalyst generally gave higher m-xylene conversion, the pre-coked catalyst produced highe...

The acid properties of mesostructured aluminosilicates synthesized from gels precursors of colloidal ZSM-5 zeolite have been studied by FTIR spectroscopy of basic probe molecules (ammonia, CO and propene). It is shown that these materials possess stronger acid sites with higher thermal stability than those of conventional Al-MCM-41. These results explain the enhaced m-xylene isomerization activ...