CO2 Hydrogenation over Nickel

CO2 hydrogenation to methane is an attractive method to convert CO2 from the atmosphere or from industry to fuel or building block for other chemicals. Open questions in the field of CO2 hydrogenation to methane which this thesis aims to adress include the structure sensitivity of the reaction and the active reaction mechanism. Chapter two of the thesis covers a literature review of the reaction mechanism from a spectroscopic point of view, commenting on the various methods to discern active reaction intermediates from spectator species. In chapter three we explore synthetic methods to yield well defined catalysts sets to study structure sensitivity. We use solution-based colloidal synthesis methods to grow Ni nanoparticles, which are then deposited on five different support materials. After a reduction step some of the Ni particles have grown severely on some supports, while they remain small on silica. Chapter four features a study towards the structure sensitvity of the reaction mechanisms. Using 'probe molecules' formic acid, methanol and CO2 the reaction network is entered at various positions, after which conversion to various other surface species is observed. Catalysts with larger Ni nanoparticles perform several reaction steps faster, indicating a structure sensitive reaction. This method enables study of the structure senstivity of individual reaction steps instead of the reaction as a whole. Finally, chapter five details the structure in-sensitivity of N2 adsorption on Ni surfaces, and discusses the influence of hydrogen co-adsorption on the IR signature of N2 adsorption.