Structure-activity relationships in heterogeneous catalysis are challenging to be measured on a single-particle level. For the first time, one X-ray beam is used to determine the crystallographic structure and reactivity of a single zeolite crystal. The method generates μm-resolved X-ray diffraction (μ-XRD) and X-ray excited optical fluorescence (μ-XEOF) maps of the crystallinity and Brønsted reactivity of a zeolite crystal previously reacted with a styrene probe molecule. The local gradients in chemical reactivity (derived from μ-XEOF) were correlated with local crystallinity and framework Al content, determined by μ-XRD. Two distinctly different types of fluorescent species formed selectively, depending on the local zeolite crystallinity. The results illustrate the potential of this approach to resolve the crystallographic structure of a porous material and its reactivity in one experiment via X-ray induced fluorescence of organic molecules formed at the reactive centers.
Lokale Kristallinität und säurekatalysierte Reaktionen in einem Zeolith‐Einkristall wurden mit Mikroröntgenbeugung (μ‐XRD) und optischer Fluoreszenz nach Anregung fluoreszierender Reaktionsprodukte (μ‐XEOF) mit einem Röntgen‐Strahl ermittelt. Verwachsungen und die Al‐Verteilung sind entscheidend für das Maß an Entaluminierung und die formselektive Produktbildung.
Keywords: Chemische Bildgebung; Heterogene Katalyse; Röntgenbeugung; ZSM-5; Zeolithe.