Anthony S. Fung

MCM-36: The first pillared molecular sieve with zeoliteproperties

Publisher Summary This chapter describes the physical characterization of MCM-36, which unequivocally establishes its existence as a novel large pore pillared material with zeolite properties. MCM-36 is a pillared material obtained from MCM-22 layers. The preparation of MCM-36 involves a lamellar intermediate, designated MCM-22 precursor, produced in a hydrothermal process. The structural information concerning pore system of MCM-36 is revealed by adsorption methods. The layers in MCM-22 posses two kinds of pore systems. One consists of 10-ring interconnected channels within the layers. The second are isolated 12-ring cages on the surface, which result in pockets on the outside of MCM-22 crystal and internal supercages, accessible through 10-ring apertures, inside the crystal. Accordingly, the pore size distribution plot obtained for MCM-22 by Ar physisorption shows two distinct peak in the 6–7 A region. The complex pore structure of MCM-22 is also reflected in the unique three step uptake profile of bulky 2,2-dimethylbutane (DMB) observed in the dynamic sorption experiment.