Direct exfoliation of layered zeolite Nu-6(1)

Nu-6(1) is a layered zeolite that can be converted by calcination into the framework zeolite Nu-6(2). In addition, Nu-6(1) can give rise to the delaminated zeolite ITQ-18 by treatment with a cationic surfactant and ultrasounds. This work reports the monitoring by Vis-UV spectroscopy of the desorption of the template species (4,4′-bipyridine) from zeolitic precursor Nu-6(1) when carrying out Na+ and CTA+ (cetyltrimethylammonium) ion exchange. Different conditions of pH and temperature were tested. No swelling was observed. However, mild conditions (pH around 9 and ambient temperature) were identified as leading to the direct exfoliation of Nu-6(1). This exfoliation produced, upon calcining, exfoliated Nu-6(2) which presents the XRD pattern of Nu-6(2) and a BET specific surface area of around 300 m2/g. Conventional Nu-6(2) has an area of about 50 m2/g. The characterization of the obtained materials was completed with TGA, XRF, SEM, TEM, SAED, and 29Si NMR analyses.

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► Monitoring by Vis-UV spectroscopy of the desorption of the template species (4,4′-bipyridine) from zeolitic precursor Nu-6(1) when carrying out Na+ and CTA+ (cetyltrimethylammonium) ion exchange.
► Identification of mild conditions (pH around 9 and ambient temperature) for the direct (without swelling) exfoliation of Nu-6(1).
► Obtaining of exfoliated Nu-6(2) with the XRD pattern of Nu-6(2) and a BET specific surface area of 300 m2/g.