Detemplation of [B]MFI zeolite crystals by ozonication

Silanol nests within zeolites can be used as catalytic centres, or to facilitate T atom insertion. Deboronation provides a way of increasing the number of silanol nests. However, at high calcination temperatures, required to remove the templates, the silanol nests are condensed. Using ozone, the temperature required for calcination can be decreased drastically. Boron containing MFI type zeolite powder ([B]MFI) has been successfully detemplated by means of ozonication. After 18 h at 473 K under a flow of oxygen containing 80 g . Nm(-3) ozone, the template molecules are removed, while 80% of the boron is retained in the framework. The detemplation is confirmed by TGA as well as DRIFT analysis. The boron can subsequently be leached out using a HCl solution leaving silanol nests. (29)Si Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) shows the ozonicated and deboronated [B]MFI sample exhibits an increased number of silanol groups (13 Si-OH/u.c.) compared to conventionally deboronated [B]MFI (9 Si-OH/u.c.) and ozonicated silicalite-1 (8 Si-OH/u.c.). This method provides a faster and easier way of synthesizing MFI zeolite with a larger number of silanol groups, than previously developed methods, even without leaching of boron. (C) 2008 Elsevier Inc. All rights reserved.