Mesopores in USY Zeolites

Zeolites of type NaY synthesised by use of seed-solution and zeolite X-secds to initialise the crystallisation were compared. A different homogeneity of the internal framework structure related to the Si/Al ratio was expected. Thus, the formation of closed bulk mesopores should be influenced during treatment of NH4NaY modification for 7 hours at 450 degrees C and 600 degrees C, respectively, in the water steam of l bar. Occurrence of different mesopores was actually observed in obtained ultra-stable USY zeolites using nitrogen adsorption. Whereas USY prepared by use of seed-solution contains only open mesopores at the crystal surface, the X-seed synthesised material contains open and closed mesopores at the surface and in the nuclei of samples, respectively.