1 June 2017
Alessandro Coumans MSc
“Catalytic hydrodeoxygenation of biomass to sustainable fuels”
Promotores: Prof. E. Hensen, Prof. T. Weber (Eindhoven University of Technology)
Summary of thesis
The research work of Alessandro Coumans deals with catalytic methods for the upgrading of biomass into fuels and chemicals. The core of the thesis is an extensive study of hydrodeoxygenation (HDO) of model compounds, i.e. methyl oleate, triolein, representing vegetable oils, into diesel-range hydrocarbons. The kinetics of an alumina-supported NiMo-sulfide catalyst were investigated under trickle-flow conditions with a focus on the reaction mechanism, the active sites for the main reactions steps (hydrolysis, hydrodeoxygenation, decarboxylation) and catalyst stability. A study of the support (alumina, silica, silica-alumina, carbon) effect for NiMo sulfide identified carbon as the most suitable support: carbon-supported NiMo-sulfide shows high intrinsic activity and is more stable than alumina- and silica-based catalysts. The periodic trends of first and second row transition metal sulfides and phosphides for the HDO of methyl valerate as a simple model compound were also investigated. A number of transition metal phosphides were investigated as catalysts for the HDO of aromatic oxygenates obtained from lignin.
22 May 2017
Peter Lewis Bramwell
“Pore-confined light metal hydrides for energy storage and catalysis”
Promotores: Prof.dr. P.E. de Jongh, Prof.dr. R.J.M. Klein Gebbink (Utrecht University)
15 May 2017
Anton Litke MSc
“Transition metal sulfides and oxides: synthesis, energy conversion application, and charge carrier dynamics”
Promotores: Prof. E. Hensen, Prof. T. Weber, Dr. J.P. Hofmann (Eindhoven University of Technology)
Summary of thesis
The main focus of the work was on gaining understanding of photocatalytic materials synthesis, parameters limiting their performance, and dynamics of photogenerated charge carriers. The systems studied are mixed Cd-Zn sulfides, titania and combinations thereof. The work can be divided into two main parts.
The first part deals with synthesis, characterization, and testing of transition metals sulfide-based materials in the visible-light driven water reduction reaction. This section explores hydrothermal synthesis of mixed Cd-Zn sulfides and their composites with TiO2.
The highlights of this work include:
• Formation mechanism of mixed Cd-Zn sulfides from mixtures of insoluble Cd and Zn hydroxides under hydrothermal conditions was elucidated.
• The effect of nano-twinned particles present in sulfide samples on their apparent activity was resolved.
• Analysis of the crystal phase composition of mixed Cd-Zn sulfides revealed the presence of compositional inhomogeneities.
• Composite materials based on highly active Cd-Zn sulfides and commercial TiO2 were explored for visible light-driven reduction of water. Electron transport in oxide particles was found to limiting performance of these materials.
The second part is devoted to investigation of charge carriers dynamics in photocatalytic materials under model conditions by steady-state and time-resolved FTIR spectroscopy. Highlights include:
• Influence of adsorbed water on dynamics of photogenerated charge carriers in P25 TiO2 photocatalysts at subsecond to minutes time scale.
• Investigation of shallow trapped electrons formation in TiO2–based materials.
• Interaction of photogenerated charge carriers with probe molecules adsorbed on TiO2-supported Pt nanoparticles.
25 April 2017
“Engineering Selective and Stable Methanol to Olefins Catalysts”
Promotores: Prof.dr. F. Kapteijn, Prof.dr. J. Gascon (Delft University of Technology)
19 April 2017
“Controlling Radical-Type Reactivity with Transition Metals and Supramolecular Cages”
Promotores: Prof.dr. B. de Bruin, Prof.dr. J.N.H. Reek (University of Amsterdam)