On the mechanism of zeolite growing:: Crystallization by seeding with delayered zeolites

Seeds of a delaminated precursor of MWW (ITQ-2) are more active for the synthesis of MCM-22 than crystals of MWW or the corresponding layered precursor. The effect is due on one hand to larger surface area and reactivity of the former, as demonstrated when seeding with MCM-41 or other delaminated zeolitic materials, and on the other hand to the crystalline structure of ITQ-2. Seeding with the delayered material yields smaller crystallites of MWW which should be positive from a catalytic point of view. The directing effect of seeding with different delayered materials on the synthesis of zeolites other than MWW is also presented. (c) 2005 Elsevier Inc. All rights reserved.