Abstract
Understanding how catalysts work during chemical reactions is crucial when developing efficient catalytic materials. The dynamic processes involved are extremely sensitive to changes in pressure, gas environment and temperature. Hence, there is a need for spatially resolved operando techniques to investigate catalysts under working conditions and over time. The use of dedicated operando techniques with added detection of catalytic conversion presents a unique opportunity to study the mechanisms underlying the catalytic reactions systematically. Herein, we report on the detailed setup and technical capabilities of a modular, homebuilt gas feed system directly coupled to a quadrupole mass spectrometer, which allows for operando transmission electron microscopy (TEM) studies of heterogeneous catalysts. The setup is compatible with conventional, commercially available gas cell TEM holders, making it widely accessible and reproducible by the community. In addition, the operando functionality of the setup was tested using CO oxidation over Pt nanoparticles.
Highlights
Most of the functional materials that are currently used in catalysis undergo dynamic changes during operation that can be expressed by alterations of their geometric or electronic states (Hansen et al, 2002; Kalz et al, 2017; Kooyman, 2017)
The system can be divided into a gas mixing stage and a flow and pressure controlling stage, which is coupled to a quadrupole mass spectrometer (QMS)
To add more flexibility to the setup, the gas feeding stage, equipped with a QMS, gas pressure and flow controllers, is movable to minimize the distance between the transmission electron microscopy (TEM) holder and the QMS (Fig. 2a)
Summary
Most of the functional materials that are currently used in catalysis undergo dynamic changes during operation that can be expressed by alterations of their geometric or electronic states (Hansen et al, 2002; Kalz et al, 2017; Kooyman, 2017). As some of these changes are thought to be stable during operation only, ex situ studies comparing pristine and spent materials alone are not sufficient to provide the complete description of catalysts at work. Probing catalysts under relevant industrial conditions (temperature, pressure, flows and gas hourly space velocity) is, challenging
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