Zeolitic intralayer microchannels of magadiite, a natural layered silicate, to boost green organic synthesis.

Yusuke Ide,Rahul Ram,Akihiko Machida,Nao Tsunoji,Satoshi Tominaka,Hiroyuki Kono

doi:10.1039/c8sc03712d

Abstract

Despite the considerable attention given to the applications of magadiite in previous research, the properties of this natural layered silicate have remained mysterious due to the lack of crystal structure information. On the other hand, no one has doubted the intercalation capability between the layers. Here we succeed in determining the structure of magadiite using X-ray pair distribution functions and synchrotron powder diffractometry. We discover unexpected zeolitic microchannels within the layers. We describe efficient synthesis of 100% pure benzoic acid from toluene by using magadiite as an additive in a TiO2 photocatalytic system oxidizing toluene. Based on the uncovered structure of magadiite, we clarify the mechanism of this unique photocatalytic system: the microchannels of magadiite not only separate/accommodate the desired partially oxidized product formed on TiO2 but also prevent the accumulation of the overoxidized products on the TiO2 surface that deactivates the photocatalytic activity.

Highlights

Development of microporous materials such as metal–organic frameworks and zeolites, with unique and better properties, is crucially important, while yet challenging, from scienti c and practical viewpoints.[1]
We revisited the structural analysis of magadiite, the natural form containing sodium ions, named “Na-magadiite”, and its protonated form, “H-magadiite”, and nally succeeded in solving their atomic structures through X-ray pair distribution function (PDF) analysis with the help of composition analysis data and other characterization data such as X-ray diffraction (XRD) and solid-state 1H and 29Si NMR data (Table S1 and Fig. S1–S7†)
As written in detail in the methodology section, we analyzed the atomic arrangement of magadiite by solving the local-to-medium-range structure by PDF analysis, determining the unit cell from the XRD pattern and determining the crystal structure by the real-space method using the network structure obtained by the PDF analysis

Summary

Introduction

Development of microporous materials such as metal–organic frameworks and zeolites, with unique and better properties, is crucially important, while yet challenging, from scienti c and practical viewpoints.[1]. ISSN 2041-6539 EDGE ARTICLE Yusuke Ide, Satoshi Tominaka et al Zeolitic intralayer microchannels of magadiite, a natural layered silicate, to boost green organic synthesis

Results

Conclusion