Strengthened by Support: Metal-Support Interactions in Nickel-based Catalysts for Carbon Dioxide Hydrogenation

We are currently facing major challenges related to the energy, resources, and materials transitions to reach the sustainability goals of 2050. One of the strategies is to reduce the emission of greenhouse gases, such as carbon dioxide (CO2). Besides reducing CO2 emissions, the CO2 itself can also be used as a carbon feedstock for producing fuels, chemicals, and materials. For this purpose, new and improved catalyst materials have to be developed that can operate under realistic conditions to facilitate these chemical conversion processes. In this dissertation, we examined the hydrogenation of CO2 to methane (or synthetic natural gas) over nickel metal nanoparticles supported on various metal oxides as catalyst materials. Through spectroscopic and microscopic tools, we zoomed in on the interaction between molecules on one hand and the nickel metal nanoparticles and metal oxide support material on the other hand. The overall aim is to improve catalyst performance. Infrared light spectroscopy is a powerful technique for following the intermediate steps of the chemical reaction and thus discovering structure-composition-performance relationships. This dissertation has shown that by changing the support material, we can modify the reaction mechanism on the catalyst surface and obtain different activities and selectivities. By using titanium dioxide, we demonstrated that the catalyst's performance depends on the different crystal structures and the reduction temperatures during pretreatment. Finally, we describe how nickel-based catalysts can be used to produce CH4 at high conversion levels, and that this can be coupled with other systems, such as the reaction from methane to aromatics, to produce valuable chemical building blocks, like benzene and toluene. This highlights the promise of catalysis to mitigate CO2 emissions from industrial point sources, thereby reaching the sustainability goals.