Dealumination of HY zeolites

As observed previously (11,12) dealumination of HY zeolites during steaming leads to the formation of extraframework aluminium species (AlNF) a part of which remains in the microporous structure. These AlNF species (AlOx groups) act as... [Pg.266]

Progressive steam dealumination of HY zeolite at high temperatures causes the same effect observed above for high temperature calcination (149,... [Pg.192]

In Section V it was shown that the Si/AI ratio has a strong influence o the acidic properties of zeolites. Dealumination, as discussed previously, is a widely used means of changing the acid character of zeolite catalysts. Such changes in the acid strength distribution are manifested as changes in catalytic behavior. For example, dealumination of HY zeolites increased the catalytic activity for cumene cracking at 573 K, reaching a maximum at a... [Pg.231]

AICI3 reacts with the chloride salt of the alkali metals and forms the corresponding alkali metal tetrachloro aluminate complexes (ref.26). The aluminium atoms of these complexes exhibit a chemical shift of ca. 100 ppm (refs.29,33) with respect to aqueous sodium aluminate. HCl and AICI3 are formed during dealumination of HY zeolites (ref.28). [Pg.361]

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