X-ray Analysis in Catalyst Research

X-ray Diffraction (XRD) is a fundamental tool in the design, development, and manufacture of catalytic materials as it can provide information on the bulk structure and composition of solid catalysts like metal oxides and zeolites. XRD instruments are regularly used to monitor the manufacture of FCC catalysts and are especially useful for analyzing unit cell sizes and crystallinity. XRD can also be used to determine crystallite size by analyzing peak width from typical diffraction measurements or by using small-angle X-ray scattering (SAXS). Non-crystalline materials can be explored using pair distribution function (PDF) analysis. Malvern Panalytical offers benchtop XRD systems like Aeris for routine analysis and floor-standing XRD devices like Empyrean for more detailed structural analysis.

X-ray Fluorescence (XRF) is widely used to analyze the elemental composition of various catalysts due to its high accuracy and reproducibility. Examples include measuring Pt, Pd, Rh in catalytic converters, Al, Ni, V, Ti, Fe, S in FCC catalyst processes, and the Si/Al ratio in zeolites.

XRF is also used to detect the presence and concentration of catalyst poisons which can cause chemical deactivation, such as Cl, S, Sn, and Pb. Compared to other measurement techniques, X-ray fluorescence analysis can save significant time and cost. Malvern Panalytical provides the Epsilon series for benchtop XRF systems, Wavelength Dispersive X-ray Fluorescence Spectrometers Zetium, and Epsilon Xflow for online elemental analysis.

X-ray Photoelectron Spectroscopy (XPS) is a method that analyzes what is happening within the catalytic processes by observing the surface of catalyst particles. Catalytic reactions occur on the surface of the catalyst, where chemical bonds are formed and broken during the reaction. XPS allows scientists to observe the elemental composition and chemical states on the catalyst surface, including reaction mechanisms, active sites, and the mechanisms behind deactivation.

X-ray Absorption Spectroscopy (XAS) is a critical method in catalyst research that provides detailed information about the local structure and electronic properties of catalysts. Similar to XPS, it can provide similar information, but it also shows how specific elements behave within bulk rather than being limited to the surface. This is crucial, as it is important to understand reactions on a larger scale in catalyst research, and many reactions occur within the bulk material due to the porous structure where catalysts are supported. XAS is typically performed at synchrotrons, and with the advantage of a powerful light source, it is possible to track all reactions in situ and in real-time without bringing the catalyst into the analyzer.