Organic−Inorganic Hybrid Zeolites with Framework Organic Groups

Abstract

A novel type of organic−inorganic hybrid zeolite has been successfully synthesized, in which lattice oxygen atoms are partially superseded by methylene groups. Various types of hybrid materials with the LTA, MFI, and *BEA structures are obtained from an organosilane in which a methylene group bridges two silicon atoms under synthesis conditions similar to those for conventional zeolites. The presence of a methylene group in the framework is demonstrated by 29Si and 13C MAS NMR and IR, although the Si−C bonds are partially cleaved during the hydrothermal synthesis to give rise to terminal methyl groups. The organic framework is thermally stable enough to remain after the combustion of the occluded organic structure directing agents (SDAs). The thermal stability of the organic framework is much higher than that in amorphous materials synthesized from the same silicon source and is dependent on the zeolite structures. The SDA-free materials not only show microporosity like ordinary zeolites but also exhibit distinctively high lipophilicity/hydrophobicity in a shape-selective way. These findings clearly indicate that these materials are not physical mixtures of conventional inorganic zeolites and amorphous organic-containing materials but contain true organic−inorganic hybrid zeolites.

The effect of framework organic moieties on the acidity of zeolites: A DFT study

“…Recently, Yamamoto et al [5,6] have prepared successfully a new family of microporous molecular sieves (MMS) called ZOL. ZOL refers to zeolites with organic groups bridged lattices and are defined as a true hybrid organic-inorganic material, where true means that the organic moieties, i.e., methylene groups (CH 2 ) are incorporated in the framework of the zeolites.…”

ECS‐3: A Crystalline Hybrid Organic–Inorganic Aluminosilicate with Open Porosity

“…[5] A more successful approach for synthesizing hybrid zeolites involves using bis-silylated organic precursors of general formula (R'O) 3 SiÀRÀSi(OR') 3 (R = CH 2 , CH 2 CH 2 ; R' = CH 3 , CH 2 CH 3 ) as silica source. [6][7][8] However, the much lower than expected organic content indicates that the Si À C bonds undergo hydrolysis. In any case, incorporation of methylene groups within the zeolite framework (an isomorphous substitution of ÀOÀ by ÀCH 2 À) is still debated because of the impossibility to distinguish a methylene group in the framework from one in the amorphous impurities that are usually present.…”

Direct Synthesis of Functional Zeolitic Materials

“…The organomodified LTA zeolite showed larger n-hexane adsorption capacity than regular LTA zeolite. The same authors reported the preparation of other organo-modified zeolitic materials, ZOL family [86,87]. Díaz et al [88] and Su et al [89] have described the synthesis and characterization of new hybrid organozeolites containing high organic content following a similar synthesis methodology to Yamamoto.…”