Homepage

mmc2021 Abstract Database

Seeing is believing: atomic-scale imaging of catalysts under reaction conditions

Seeing is believing: atomic-scale imaging of catalysts under reaction conditions

Session

Stream 3: Operando Microscopy

Authors

Dr. Irene Groot (1)

Affiliations

1. Leiden Institute of Chemistry, Leiden University

Keywords

in situ measurements, scanning probe microscopy, optical microscopy, model catalyst, hydrodesulfurization, graphene growth, surface science, heterogeneous catalysis

Abstract text

The atomic-scale structure of a catalyst under reaction conditions determines its activity, selectivity, and stability. Recently it has become clear that essential differences can exist between the behavior of catalysts under industrial conditions (high pressure and temperature) and the (ultra)high vacuum conditions of traditional laboratory experiments. Differences in structure, composition, reaction mechanism, activity, and selectivity have been observed. These observations made it clear that meaningful results can only be obtained at high pressures and temperatures. Therefore, the last years have seen a tremendous effort in designing new instruments and adapting existing ones to be able to investigate catalysts in situ under industrially relevant conditions.

In this talk, I will give an overview of the in situ imaging techniques we use to study the structure of model catalysts under atmospheric pressures and elevated temperatures. We have developed setups that combine an ultrahigh vacuum environment for model catalyst preparation and characterization with a high-pressure flow reactor cell, integrated with either a scanning tunneling microscope or an atomic force microscope. With these setups we are able to perform atomic-scale investigations of well-defined model catalysts under industrial conditions. Additionally, we combine the structural information from scanning probe microscopy with mass spectrometry measurements. In this way, we can correlate structural changes of the catalyst due to the gas composition with its catalytic performance. Furthermore, we use other in situ imaging techniques such as transmission electron microscopy, surface X-ray diffraction, and optical microscopy, all combined with mass spectrometry. In addition, we make use of near-ambient-pressure X-ray photoelectron spectroscopy to obtain chemical information on the model catalysts during reaction. Scientific cases that I will discuss are hydrodesulfurization of S-containing organic molecules on (Co-promoted) MoS₂ and graphene growth on liquid copper.