INFLUENCE OF THE TREATMENT OF MORDENITE BY AMMONIUM HEXAFLUOROSILICATE ON PHYSICOCHEMICAL AND CATALYTIC PROPERTIES

Different samples were prepared by treating a NH(4)MOR sample (Si/Al = 5) with ammonium hexafluorosilicate. The dealumination of the outer s urface of mordenite crystallites was more pronounced than that of the bulk. A decrease in the adsorption rate and capacity for organic molec ules and in activity and stability for m-xylene transformation was obs erved. Furthermore, the isomerization selectivity was improved because of inhibition of desorption of bulky products of m-xylene disproporti onation. All of these observations can be related to a dealumination o f the mordenite limited to the pore mouth with deposit, at the entranc e of channels, of aluminum species extracted from the framework.