Exploring new catalysts for conversion of sustainable energy in μ-reactors: Study of mass-selected atoms, clusters, and nanoparticles

This PhD thesis investigates catalytic reactions under reaction conditions that is comparable to industrial catalysts.
Heterogeneous catalysis plays a pivotal role in the transition to a renewable energy future, moving away from fossil fuel-based energy sources and contributing to clean energy access for all, in accordance with United Nation (UN) Sustainable Development Goal 7 (SDG 7). In this thesis, a Si-based μ-reactors is used to investigate heterogeneous catalysis, bridging the pressure gap between traditional academic surface science and industrially viable catalytic reaction conditions.
The μ-reactor, a state-of-the-art testing platform, allows for activity testing and analysis of catalytic reactions under a wide range of conditions. In this work, the primary study is the investigation of AuTi mass selected nanoparticles in the size range of 28 nm for their potential application in thermal catalysis. By alloying Au with Ti, AuTi nanoparticles is expected to exhibit enhanced stability compared to Au on SiO₂, which is then evaluated systematically for their catalytic performance using the μreactor.
The key reaction studied in this thesis is CO oxidation, a well known process with industrial applications.
Through this work, the μ-reactor platform has demonstrated the versatility and potential as a powerful tool for investigating heterogeneous catalysis it is.
During this work, it has been important to enhance the technical aspects of the μ-reactor. This research examines the calibration processes of the quadrupole mass spectrometer (QMS). An understanding of this procedure is important, as it sets the stage for accurate and reliable data analysis in subsequent experimental stages. Complementing this is the validation the molecular flow through the capillary of the μ-reactor to enable calibration of gasses not available as a pure gas or as a gas mixture for direct calibration in the QMS. Technical effort is put into setting up and optimising protocols for using the μ-reactors in catalysis research. Detailed attention is given to the heating methods and monitoring of temperatures in vacuum, ensuring that the reactors are heated homogeneous and the true temperature is reported for optimal performance across various experimental scenarios.
The platform relies heavily on the anodic bonding procedure to hermetically close the reactor prior to testing. This step has proven to include huge variation and unreliable catalytic testing for the AuTi system investigated and effort is put into designing and conceptualising a new reusable μ-reactor-platform for thermal catalysis as is the case for Electrochemical Catalysis (EC) and is proven to work for Photocatalysis.