X‐ray Imaging of Zeolite Particles at the Nanoscale: Influence of Steaming on the State of Aluminum and the Methanol‐To‐Olefin Reaction

Abstract

We thank the NRSC-C (B.M.W.), the NWO-CW Top (B.M.W.), and the NWO-CW VICI (F.M.F.d.G.) for financial support and D. Cabaret (IMPMC, UniversitØ Pierre et Marie Curie) for providing the aluminum references. T. Tyliszczak (Lawrence Berkeley National Laboratory), J. Wang (Canadian Light Source), S. Svelle (University of Oslo), and A. M. J. van der Eerden (Utrecht University) are kindly thanked for their contributions.

3D Nanoscale Chemical Imaging of the Distribution of Aluminum Coordination Environments in Zeolites with Soft X‐Ray Microscopy

“…They correspond to 89 % and 11 % of 4-fold and 6-fold aluminum, respectively. It is comforting to see that these numbers are very close to those obtained by 27 Al MAS NMR measurements on ZSM-5-C. [29] Indeed, the NMR results of 87 % for 4-fold aluminum and 13 % for 6-fold aluminum are in line with the average numbers from the 3D STXM data analysis. In other words, the nanoscale imaging data are corroborated by independent bulk measurements on the same material.…”

“…[29] As a consequence, the STXM image obtained by subtracting the X-ray absorption at E 1 from that at E 2 is not indicative of a single alumi- Figure 1. Soft X-ray K-edge absorption spectra of aluminum for reference compounds albite (blue) and corundum (red), including the three energies (E 1 , E 2 and E 3 ) measured at every projection angle during the scanning transmission X-ray microscopy (STXM) tomography measurements.…”

Aluminum-Phosphate Binder Formation in Zeolites as Probed with X-ray Absorption Microscopy

“…62 25 The results of this fitting procedure are presented in Figure S9 and it can be observed that the fit correlates very well with the original spectra. We applied the same method to an H-mordenite sample that was steamed at more severe temperatures (500 °C) and found the fit to be good as well.…”

“…It has been shown previously that the coordination of aluminum in H-ZSM-5, H-beta and H-mordenite change upon dehydration as octahedrally coordinated aluminum is reverted into four-or three-coordination. 25,48,49 …”

“…Our group has recently been applying STXM in the field of zeolite chemistry and catalysis. [25][26][27]77 Using this experience it was possible to observe the crystallization of the extra-framework AlPO 4 phase of H-mordenite in space and time by application of an in situ nanoreactor. 28 X-ray tomography was used to create a 3-D nanoscale chemical reconstruction of the AlPO 4 phase in a single H-mordenite aggregate for the first time.…”