Synthesis of new MCM-36 derivatives pillared with alumina or magnesia–alumina

Abstract

Alumina and magnesia-alumina have been applied for pillaring the layered precursor of zeolite MCM-22. Calcination of such materials has led to new varieties of MCM-36 molecular sieves. Pillaring with alumina yields mesoporous materials with lower surface areas than those pillared with silica. The pillaring process with alumina strongly depends upon the preparation conditions of the alumina species and requires an elongated aging of the pillaring solutions. Application of magnesia in addition to alumina results in a higher exfoliation of the MCM-22 layers and incorporation of an increased amount of alumina into the materials. MgO 6 Al 2 O 3 as pillaring agent yields a significantly higher mesoporosity in the range of 2-4 nm as compared with Al 2 O 3 . This synthesis method is a promising tool for tailoring the physicochemical properties and the structure of the slit-mesopores in relation to materials typically pillared with silica.

Preparation of microporous pillared magadiite from silylated magadiite and their unique inclusion behaviors of organic molecules

“…Among the resulting materials, pillared layered silicates are expected for the application of adsorption, catalysts, support of catalysts, molecular sieves, etc. Pillaring with polymeric silica or metal oxides such as titania, alumina and zirconia has been reported for various layered silicates, such as magadiite [2][3][4][5][6], kenyaite [7,8], octosilicate [9], MCM-22 [10][11][12][13], kanemite [14], kenyaite [15] and potassium layered silicate with kenyaitelike structure [16]. These pillared layered silicates are usually obtained by intercalation of polycations as precursors of pillars into interlayered regions of layered silicates and subsequent calcinations of the resulting materials.…”

One-pot synthesis of hierarchical porous layered hybrid materials based on aluminosilicate sheets and organic functional pillars

“…Moreover, it is difficult to avoid an inhomogeneous distribution of organic pillars located in the interlayer space, which could be a problem during the catalytic reactions. 32 There is no doubt that it would be of much interest to synthesize 39 The crystal structure determination has shown that an elevated number of these lamellar materials contain a double porous system: intra-layered conformed by microporous channels normally delimited by six member rings (6MR), and an inter-layered space owing to the galleries generated between inorganic sheets and rigid aromatic linkers. In this way, layered hybrid materials with specific surface areas and porous volumes, sometimes, close to 350 m 2 g -1 and 0.70 cm 3 g -1 were obtained.…”

Layered zeolitic materials: an approach to designing versatile functional solids

“…In this way, magnesia-alumina were used for pillaring the MWW layered zeolitic precursors, obtaining MCM-36 materials with significantly higher mesoporosity (pore size diameters between 2-4 nm) compared with the use of only alumina as structural pillars. 72 as acid-base bi-functional materials which would contain enhanced Lewis and Brönsted acidity, generated by pillaring with aluminum oxides and/or silica-alumina clusters, and base properties by the incorporation of alkaline earth oxide aluminates (MgO/BaO-Al 2 O 3 ), both located between the zeolitic layers in the interlayered space.…”