Catalyst Characterization
M. F. Baidoo
5.02.2024
What is Catalyst Characterization?
The determination of physical and chemical
properties responsible for the performance
of the catalyst in a reaction.
Which Properties are determined?
• Chemical Composition of the Bulk and Surface of the
Solid
• Surface Area and Porosity (micro, meso and macro)
• Bulk Solid Structure, Phase Composition, Crystallite
Size
• Surface Morphology (Shape, texture and distribution
of a material at a surface)
Which Properties are determined?
• Surface chemical properties such as:
• Location and oxidation state of active metals
• Acid-base property
• Reducible-oxidizable property
• Aggregate properties such as particle size, density,
mechanical strength and attrition resistance
• Catalytic properties such as: activity, selectivity,
stability
Why is Characterisation Important?
• Primary objective is to understand the relationship between
physical, chemical and catalytic properties.
• Essential for catalyst design and process optimization.
• Monitor changes in physical and chemical properties of
catalysts during preparation, activation and reaction stages
for better understanding and quality control.
• Determine the extent of deactivation during the reaction
process and how to minimize it.
• Helps to design procedures for catalysts regeneration.
Mode of Characterisation
Ex situ or In situ or
operando
Ref: Zaera, F., In-situ
and operando
spectroscopies for the
characterization of
catalysts and of
mechanisms of catalytic
reactions, J. Catal.
Volume 404, December
2021, Pages 900-910
Application of In situ Catalyst Characterisation
Ref: Zaera, F., In-situ and operando spectroscopies for the characterization of catalysts and of mechanisms of catalytic reactions, J. Catal. Volume 404, December 2021, Pages
900-910
Description of image on previous slide
Example of the use of IR in operando mode to follow the formation
and consumption of surface intermediates during catalysis [27]. (a)
IR spectra acquired at different times after the start of an ethylene
hydroformylation reaction promoted by a Rh/alumina catalyst,
highlighting the peak at 1636 cm1 due to the C–O stretching (m(C–
O)) frequency of a propionyl surface intermediate (shown in red on
the right). (b) Plot of the peak signal intensity of that feature as a
function of time to show its transient nature and to calculate the
kinetic parameters of the reaction. Adapted. from Ref. [27] with
permission, Copyright 2011 American Chemical Society. (For
interpretation of the references to colour in this figure legend, the
reader is referred to the web version of this article.)
Catalyst Characterisation Techniques
• Structural analysis
• BET surface area
• Pore analysis: mercury intrusion , BJH method
• XRD
• Chemisorption
• Temperature programmed methods
• TPR/TPO
• TPD
• TPSR
• DTA
• TGA
Catalyst Characterisation Techniques
• Nuclear Magnetic Resonance
• Spectroscopic techniques Infrared spectroscopy
Raman spectroscopy EXAFS/XANES/XAS
XPS-Auger UV-Vis-NIR
• Microscopic techniques
Scanning Electron Microscopy
Transmission Electron Microscopy
