Influence of layer structure preservation on the catalytic properties of the pillared zeolite MCM-36

MCM-36 is a catalytically active material made by swelling and subsequent pillaring of a layered zeolite precursor, MCM-22(P). However, the swelling procedures lead to significant destruction of layer structure and alteration of framework silicon/aluminum (Si/Al) ratio, which are likely to influence the acidity and catalytic activity of the final materials. We report a milder swelling and pillaring process to prevent such structural destruction. The resulting pillared materials show higher crystallinity and improved retention of the zeolitic layer structure when compared to the ones prepared by the previously reported methods involving more aggressive treatments. Implications of such structural preservation on the physicochemical, acidic and catalytic properties of the materials have been investigated using a variety of characterization methods. The milder swelling results in catalytic materials with stronger acid sites and, at similar Si/Al ratios, higher acid site density and higher catalytic activity when compared to the MCM-36 materials produced using the previously reported more aggressive swelling process. (C) 2010 Elsevier Inc. All rights reserved.