This work describes several studies into the electroreduction of carbon dioxide (CO2RR), both regarding mechanistical aspects and catalyst stability considerations. Mechanistic insights into carbon... Show moreThis work describes several studies into the electroreduction of carbon dioxide (CO2RR), both regarding mechanistical aspects and catalyst stability considerations. Mechanistic insights into carbon-carbon bond formation on a silver catalyst are described in Ch 2, were we find an acetaldehyde-like surface adsorbate to be a key intermediate. Gold stability in alkaline environment under strongly reducing conditions and the effect of near-surface CO on said stability is reported on in Ch 3, showing catalyst degradation under reductive conditions which is furthermore exacerbated by CO adsorption. Chapter 4 details the voltammetric behavior of variously oriented copper surfaces when prepared via a non-standard methodology, showing good agreement with prior literature. The last chapter (Ch 5) contains investigations into the stability of copper under reductive conditions in near-neutral buffered electrolyte and in alkaline electrolyte, where it was observed that copper is morphologically stable under strongly alkaline conditions and neutral conditions in the presence of CO2 and buffer ions, so long as strictly reducing potentials are applied. Show less
Bunschoten, A.; Chin, P.T.K.; Buckle, T.; Linden, M. van der; Barendregt, A.; Verheijen, M.A.; Leeuwen, F.W.B. van 2016
Clearly gold deposited as nanoparticles on a support is a very active catalyst in contrast to bulk gold which does not show any catalytic activity. The question arises if this particle size effect... Show moreClearly gold deposited as nanoparticles on a support is a very active catalyst in contrast to bulk gold which does not show any catalytic activity. The question arises if this particle size effect is exclusively valid for gold catalysis or can a similar effect be found in other metals? In the research described in this thesis we investigated copper and silver based catalysts for similar particle size effects as for gold based catalysts. In contrast to gold bulk silver and copper are known to be active in catalysis and both metals are used as catalysts. Silver is the metal of choice for the formation of ethylene oxide from ethylene but also for the formation of formaldehyde in the BASF process. A Cu/Zn-based catalyst is used for the synthesis of methanol from CO and \hydrogen, and copper-based catalysts are also active in oxidation reactions. As the interaction between the gold nanoparticles with the additives is very important for the catalytic activity, the effect of additions of lithiumoxide and ceria have also been investigated for the silver and copper based catalysts. These additives stabilize the nanoparticles and ceria which is known for its oxygen storage and oxidation capacities and is one of the best additives for gold based catalysts. Various oxidation and dehydrogenation reactions have been investigated over copper, silver and gold based catalysts, which are presented in this thesis. In chapter 2 the preferential oxidation of CO is discussed. Chapter 3 deals with the selective oxidation of \ammonia. Chapter 4 is devoted to the oxidation and dehydrogenation of methanol. Chapter 5 presents the results of formation of ethylene oxide in the oxidation and dehydrogenation of ethanol on silver and copper based catalysts. In chapter 6 more results of ethanol dehydrogenation and oxidation on gold based catalysts are presented. Chapter 7 gives insight into the activity of gold based catalysts in oxidation and dehydrogenation of 1-propanol and 2-propanol. Show less
The study of gas-surface interaction dynamics is important both for the fundamental knowledge it provides and also to aid the development of applications involving processes such as sputtering,... Show moreThe study of gas-surface interaction dynamics is important both for the fundamental knowledge it provides and also to aid the development of applications involving processes such as sputtering, plasma etching and heterogeneous catalysis. Elementary steps in the interactions, such as chemical reactions, adsorption and scattering are prototypical of more complex processes and better understanding of them deepens our knowledge of such processes. In addition, experimental measurements of specific interactions can be used to validate advanced computer models. Hence the experiments in this thesis have been carried out under well-defined condition, namely in ultrahigh vacuum and using high-purity single-crystal samples. The thesis is primarily focussed on understanding the interaction of hyperthermal Ar and N (~4-6 eV) with Ru(0001) and Ag(111) via scattering studies. Ar is very inert and its interaction with surfaces is primarily repulsive in nature, while N atoms probe the surface chemisorption well. From the study of Ar scattering dynamics, surface properties have been probed. From N scattering studies, chemisorption dynamics have been investigated. It is found that the electronic state of the incident particle may play an important role in the gas-surface interaction. Separately, the influence of pre-adsorbed CO on Ru(0001) on D2 dissociation have been unravelled. Show less
Described in this thesis are the investigations into the chemistry of N-heterocyclic carbene (NHC) ligands and transition-metal complexes thereof. Specifically, a variety of N-heterocyclic carbene... Show moreDescribed in this thesis are the investigations into the chemistry of N-heterocyclic carbene (NHC) ligands and transition-metal complexes thereof. Specifically, a variety of N-heterocyclic carbene complexes of nickel were prepared, characterized and used as catalysts in three types of homogeneous catalytic processes. First, nickel(II) complexes of monodentate NHC ligands were successfully used as catalysts in the hydrosilylation of internal alkynes. Second, nickel(II) complexes bearing bidentate N-heterocyclic carbene ligands or functionalized NHC ligands were shown to be highly effective in the Kumada coupling of aryl halides with aryl Grignard reagents. In addition, the nickel-catalyzed Kumada coupling was investigated using quantum-chemical calculations. Finally, all three types of nickel complex were tested for their catalytic activity in the vinyl polymerization of norbornene. Furthermore, a silv er(I) NHC complex was isolated, characterized and used in the preparation of a nickel(II) NHC complex. Show less
Against the background of a regional crisis caused by dynastic change in China and the closure of Japan in the middle of the seventeenth century, the Vietnamese kingdom of Tonkin rose to the fore... Show moreAgainst the background of a regional crisis caused by dynastic change in China and the closure of Japan in the middle of the seventeenth century, the Vietnamese kingdom of Tonkin rose to the fore as the major silk producing and exporting region in East Asia.Based on a wealth of so far unused primary sources from the Dutch East India Company (VOC) archives, this monograph explains how Dutch maritime traders played a critical role in Tonkin’s dramatic emergence as a trading power. The author examines the vicissitudes in political relations, the varying trends in the VOC-Tonkin import and export trade, and the Dutch influence on the seventeenth-century Vietnamese feudal society. Show less
