(740d) Nanoscale Catalytic Materials by Swelling, Pillaring and Exfoliation of a Zeolite Precursor
The zeolite MCM-22 is formed by calcination of a layered precursor, MCM-22(P). The layered structure of the precursor allows swelling, pillaring and exfoliation to single layers to produce a host of nanomaterials[2,3]. However, these procedures result in significant degradation of the structure of the layers with partial loss of crystallinity[4,5]. In this work, we describe a modified approach to swell, pillar and exfoliate the MCM-22 layered precursor with improved preservation of crystal morphology and alumino-silicate layer structure. XRD reveals that the swollen derivative evolves to a new ordered layer structure upon washing with water. Solid state NMR spectroscopy indicates preservation of framework connectivity. This ordered material can act as starting material to form inorganic/organic hybrid catalysts with specific guest-host interactions. Interestingly, the swollen derivative can be restored back to the precursor structure by acidification. It can be successfully pillared to produce an MCM-36 analogue or exfoliated to produce a high surface area material analogous to ITQ-2 but with improved crystallinity. The resulting materials are expected to exhibit distinct catalytic behavior compared to the pre-existing analogues, due to the improved preservation of the pore structure and catalytic sites.
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