Catalyst design for clean and efficient fuels

This thesis contains a theoretical approach to specific problems in catalysis and is based upon fundamental concepts from thermodynamics and density functional theory calculations. It investigates the already existing and well established process of hydrodesulfurization and a novel process of synthesizing dimethyl carbonate electrochemically.
Hydrodesulfurization is an industrial refining process in which sulfur is removed from oil in order to reduce SO₂ emissions. The study on hydrodesulfurization involves determining the active sites and their atomic scale structure for the industrially used cobalt promoted MoS₂ catalyst. Reactivity of a series of model molecules, found in oil prior to desulfurization, is studied on cobalt promoted MoS₂. Such an approach has the potential to explain the underlying processes involved in the removal of sulfur at each specific site of the catalyst. The goal is to identify which sites are active towards specific molecules and in getting insight to what the ideal catalyst should look like in terms of morphology. Dimethyl carbonate is an environmentally benign compound that can be used as a solvent and precursor in chemical synthesis or as a fuel and fuel additive. It can replace different toxic compounds that are nowadays used as precursors for various reactions. An electrocatalytic process for synthesizing dimethyl carbonate is studied as part of this thesis. Producing dimethyl carbonate electrochemically makes it possible to avoid using hazardous chemical processes currently used. It is found that noble metals can be used as electrocatalysts for the synthesis of dimethyl carbonate, significantly lowering the potential when using copper instead of gold. Besides being active, copper was found to be selective towards dimethyl carbonate. A non-selective catalyst will yield unwanted coproducts, causing the need for additional separation techniques to extract pure dimethyl carbonate after synthesis. This in return increases the production cost of dimethyl carbonate.
This thesis is another step in the collective effort to make today’s fuels and chemicals environmentally friendlier and creating new, efficient and clean technologies for chemical and fuel production.