Issue 3, 2016

Development of a post-synthetic method for tuning the Al content of OSDA-free Beta as a catalyst for conversion of methanol to olefins

Abstract

Zeolites synthesized without any organic structure-directing agent (OSDA) have several advantages over conventional zeolites synthesized with OSDAs. Their Al-rich compositions, however, are sometimes not suitable for applications as catalysts. In the present study, post-synthetic modification was performed using an Al-rich Beta zeolite synthesized without any OSDAs (designated as “Beta(OF)”) to obtain high-silica Beta zeolites. We have successfully developed a facile post-synthetic method for tuning the Al content of Beta(OF) with the *BEA-type structure retained by calcination at >750 °C followed by acid treatment. Solid-state 29Si and 27Al MAS NMR analyses revealed that during calcination, framework Al atoms were isomorphously substituted with Si atoms to form high-silica frameworks and concomitant extra-framework Al species. The stability of the obtained frameworks against acid treatment was evaluated in terms of the framework Al content, finding that the framework with the Si/Al ratio higher than 12 is well stabilized enough for acid treatment. Thus, dealuminated Beta(OF) zeolites with high-silica compositions were found to be effective catalysts for the methanol-to-olefin (MTO) reaction; particularly, the Beta zeolite with the Si/Al ratio of 112 maintained the conversion of methanol over 90% with selectivity to C2–C4 olefins over 70% even at 40 hours on stream at WHSV = 3.2 h−1.

Graphical abstract: Development of a post-synthetic method for tuning the Al content of OSDA-free Beta as a catalyst for conversion of methanol to olefins

Supplementary files

Article information

Article type
Paper
Submitted
24 Jun 2015
Accepted
19 Aug 2015
First published
20 Aug 2015

Catal. Sci. Technol., 2016,6, 713-721

Development of a post-synthetic method for tuning the Al content of OSDA-free Beta as a catalyst for conversion of methanol to olefins

R. Otomo, U. Müller, M. Feyen, B. Yilmaz, X. Meng, F. Xiao, H. Gies, X. Bao, W. Zhang, D. De Vos and T. Yokoi, Catal. Sci. Technol., 2016, 6, 713 DOI: 10.1039/C5CY00944H

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