Issue 37, 2019

Tracking the rearrangement of atomic configurations during the conversion of FAU zeolite to CHA zeolite

Abstract

In order to realize designed synthesis, understanding the formation mechanism of zeolites at an atomic level has long been aspired, but remains challenging due to the fact that the knowledge of atomic configurations of the species formed during the process is limited. We focus on a synthesis system that crystallizes CHA zeolite from FAU zeolite as the sole source of tetrahedral atoms of Si and Al, so that end-to-end characterization can be conducted. Solid-state 29Si MAS NMR is followed by high-throughput computational modeling to understand how atomic configurations changed during the interzeolite conversion. This reveals that the structural motif commonly found in FAU and CHA is not preserved during the conversion; rather, there is a specific rearrangement of silicates and aluminates within the motif. The atomic configuration of CHA seems to be influenced by that of the starting FAU, considering that CHA synthesized without using FAU results in a random Al distribution. A Metropolis Monte-Carlo simulation combined with a lattice minimization technique reveals that CHA derived from FAU has energetically favorable, biased atomic locations, which could be a result of the atomic configurations of the starting FAU. These results suggest that by choosing the appropriate reactant, Al placement could be designed to enhance the targeted properties of zeolites for catalysis and adsorption.

Graphical abstract: Tracking the rearrangement of atomic configurations during the conversion of FAU zeolite to CHA zeolite

Supplementary files

Article information

Article type
Edge Article
Submitted
07 jun. 2019
Accepted
06 ago. 2019
First published
07 ago. 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2019,10, 8533-8540

Tracking the rearrangement of atomic configurations during the conversion of FAU zeolite to CHA zeolite

K. Muraoka, Y. Sada, A. Shimojima, W. Chaikittisilp and T. Okubo, Chem. Sci., 2019, 10, 8533 DOI: 10.1039/C9SC02773D

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