Abstrakt
Heterogeneous catalysis is crucial branch of chemistry, having unprecedented impact on nearly every aspect of our life. Zeolites as crystalline microporous solids have found application in many industrial catalytic processes like fluid catalytic cracking (FCC), hydrogenations, polymerisations, or alkylations.
Their main advantages are defined pore structure resulting in so-called shape/size-selectivity and presence of Bronsted acid sites due to the trivalent atoms (such as Al) in the framework. The proper design of zeolite catalysts, study of the crystal formation, their morphology, structural properties, location of active species, porosity and structural determination of new materials often requires support by advanced characterisation techniques Among them, electron microscopy and related methods are often essential for the thorough description of mentioned features.
Scanning electron microscopy (SEM) and atomic force microscopy (AFM) describe the morphology and surface of crystals of zeolite catalysts. Transmission electron microscopy (TEM), including scanning mode (STEM), supported by electron diffraction (ED) methods can give crucial information about structure, especially when conventional methods are limited for the full description of solid catalysts, like zeolites.
Often those techniques are supported by energy-dispersive X-ray spectroscopy (EDS) for the elemental analysis of the samples. This chapter is an overview focused on electron microscopy and related characterisation techniques as well as their utilisation in the fields of design, synthesis, and formation of crystals, characterisation, and performance of zeolites as heterogeneous catalysts.