Studying the atomic structure of an electron beam sensitive catalyst
Typ
Examensarbete för masterexamen
Program
Publicerad
2021
Författare
Andersson, Carl
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This work concerns catalysts and the optimisation of atomic structure to increase the
catalytic efficiency and lifetime of said systems. Catalysts are used in many different
applications, for example vehicles, chemical synthesis, biological reactions and
food processing. The increasingly stringent regulations regarding vehicular emissions
have brought about an intense research in automotive catalyst systems during
the last decades. In this work we focus on the zeolite system Cu-SSZ-13, one of the
leading candidates for state-of-the-art heavy-duty automotive catalyst systems, and
developing a methodology for studying it with atomic resolution scanning transmission
electron microscopy (STEM) imaging. Proper specimen preparation is one of
the most important factors in order to achieve high-resolution. A substantial part
of this work therefore concerns the study how to optimally prepare SSZ-13 samples
for high-resolution imaging. Specifically, we try to find methods for imaging and
specimen preparation that limit electron beam damage of Cu-SSZ-13. We present
a protocol for specimen preparation of SSZ-13 that also includes information about
different means of controlling the degree of sample hydration and its effect upon the
sensitivity to electron beam damage. Beam damage effects and underlying mechanisms
are discussed as well. We also present results from simulations of atomic
resolution images of Cu-SSZ-13, which in turn can be used to support experimental
results of future works.
Beskrivning
Ämne/nyckelord
SCR , Zeolite , Cu-SSZ-13 , Electron microscopy , High resolution , HAADF STEM , Specimen preparation , Simulation