Influence of preparative conditions on the structure, acidity and catalytic activity of dealuminated Y zeolite

Deammoniation of NH4Y (NH4Y --> HY + NH3) followed by partial dehydroxylation of HY removed part of the aluminium from zeolitic framework and most of this non-framework aluminium is conveniently extracted with ethanolic solutions of acetylacetone. A series of dealuminated Y zeolite is prepared by this method varying the Si/Al ratio. These dealuminated Y zeolites are characterized by chemical analysis, XRD, BET surface area, acidity, IR, TPD of ammonia and catalytic activity in acid catalyzed reactions like cumene cracking, aniline alkylation, phenol alkylation and cyclohexanol dehydration. Shift of 1010 cm(-1) frequency in IR spectra to 1068 cm(-1) and decrease in unit cell parameter a(0) from 24.74 (NaY) to 24.32 (DHY24)(Angstrom) have demonstrated N-Al/U.C similar or equal to 12, a state of advanced dealumination. TPD of ammonia and catalytic activity over these dealuminated Y zeolites clearly show the presence of weak-moderate-strong acidity.