Emerging analytical methods to characterize zeolite-based materials

Abstract

Zeolites and zeolitic materials are, through their use in numerous conventional and sustainable applications, very important to our daily lives, including to foster the necessary transition to a more circular society. The characterization of zeolite-based materials has a tremendous history and a great number of applications and properties of these materials have been discovered in the past decades. This review focusses on recently developed novel as well as more conventional techniques applied with the aim of better understanding zeolite-based materials. Recently explored analytical methods, e.g., atom probe tomography (APT), scanning transmission X-ray microscopy (STXM), confocal fluorescence microscopy (CFM) and photo-induced force microscopy (PiFM) are discussed on their important contributions to the better understanding of zeolites as they mainly focus on the micro- to nanoscale chemical imaging and the revelation of structure—composition-performance relationships. Some other techniques have a long and established history, e.g., nuclear magnetic resonance (NMR), infra-red (IR), neutron scattering (NS), electron microscopy (EM) and X-ray diffraction (XRD) techniques, and have gone through increasing developments allowing the techniques to discover new and important features in zeolite-based materials. Additional to the increasing application of these methods, multiple techniques are nowadays used to study zeolites under working conditions (i.e., the in-situ/operando mode of analysis) providing new insights in reaction and deactivation mechanisms.

Micro‐ and Nanoscale Heterogeneities in Zeolite Beta as Measured by Atom Probe Tomography and Confocal Fluorescence Microscopy

“…[21,[26][27][28] Further studies using microscopic techniques such as μ-XRD and high resolution electron microscopy, would provide interesting insights in follow-up studies. [28,29] However, the bulk technique 27 Al NMR could be extremely important tool as it provides information on the orientation of the aluminum atoms. [30][31][32] Micro-and nanoscale coking behaviour of zeolite Beta: The hydrocarbon distribution formed after 5 and 30 min coking was studied on the hundreds of nm length scale using Confocal Fluorescence Microscopy (CFM).…”

A review of recent developments for the in situ/operando characterization of nanoporous materials

“…Recently published reviews provide a detailed overview of the theory and applications of XAFS, the details of which are beyond the scope of this article. [132,133] As discussed before, the combination of adsorption experiments with structure-sensitive methods is mandatory for understanding the structure-property relationships of porous materials. Performing in situ XRD experiments during gas adsorption into the metal-organic framework DUT-8(Ni) provides direct insight into the gate opening mechanism, which is influenced by different probe molecules.…”

Probing coke formation during the methanol-to-hydrocarbon reaction on zeolite ZSM-5 catalyst at the nanoscale using tip-enhanced fluorescence microscopy

“…confocal fluorescence microscopy (CFM), scanning transmission X-ray microscopy, atomic force microscopy (AFM) etc.). 36 By investigating zeolite ZSM-5 catalysts, subjected to 10 and 90 min of MTH reaction, we show that hyperspectral CFM allows one to visualize the formation of multiple coke species over the entire zeolite crystal surface at the submicron scale, whilst TEFL imaging can be used to zoom into a specific part of the sample and probe coke formation with a spatial resolution of up to 35 nm. Furthermore, TEFL analysis can be performed non-destructively and in a labelfree manner under ambient conditions.…”