Pengcheng Huang promoted December 16th, 2022In this thesis, a thermal-responsive polymer (p-NIPAM) that has a lower critical solution temperature (LCST) has been employed as polymer coating on a model Pd/SiO2 catalyst to validate this concept. The effect of the solvent and polymer-induced solvation effects on the reaction selectivity and activity have been studied using the nitrite and nitrobenzene hydrogenation reactions as probe chemistries.....

Maria Enes da Silva promoted December 1st, 2022Thus far, the self-regulating mechanism using stimuli responsive polymers has never been demonstrated for heterogeneous catalysis. Instead, an external stimulus is applied to alter the catalyst activity depending on the polymer conformational state when polymeric brushes are coated on a nano cluster. In the presence of a thermo-responsive polymer, such as poly(n-isopropylacrylamide) (p-NIPAM), the increase of temperature causes the polymeric brushes to collapse after surpassing a certain temperature, the so called Lower Critical Solution Temperature (LCST). .....

Kevin Rouwenhorst promoted cum laude 2022 September 9th.This PhD thesis presents an investigation into plasma-catalytic ammonia synthesis in a dielectric barrier discharge (DBD) plasma reactor. Ammonia (NH3) can be synthesized from hydrogen gas (H2) and nitrogen gas (N2). Ammonia has current applications as intermediate for the fertilizer industry and the chemical industry. About 45% of the current pure hydrogen demand in industry is used for ammonia production. Future applications of ammonia include its use as zero-carbon fuel and as hydrogen carrier. Thus, ammonia may play a significant role in a decarbonized energy landscape.

Rolf Postma promoted December 3rd, 2021This thesis presents a detailed investigation into the reaction performance characteristics of non-oxidative coupling of methane using the Fe©SiO2 catalyst. Natural gas, consisting for 75-99 vol% of methane (CH4), is seen as a high potential substitute for crude oil in the synthesis of light olefins (ethylene and propylene) and aromatics (benzene, toluene and xylene). Current industrial processes converting natural gas to olefins and aromatics consist of multiple conversion steps starting with methane steam reforming to obtain syngas. For this reason, these processes tend to be energy intensive and require large installed capacity to become economically viable.

Pengyu Xu promoted Ocktober 2nd 2020In order to gain better understanding of the mechanism of nitrite hydrogenation over Pd/γ-Al2O3 catalyst, the intrinsic kinetics was determined in a wide window of nitrite and hydrogen concentrations.

Guido Giammaria promoted February 7th 2020This research aims at the assessment of potential benefits of a Dielectric Barrier Discharge (DBD) non‐thermal plasma on the calcium carbonate decomposition, in terms of 1) decomposition temperature decrease and 2) direct conversion to added value chemicals such as CO.

Tushar Ramesh Sakpal promoted June 7th 2019This study reports the effect of metal (Ni and Ru) particle size on the activity of catalysts. Moreover, we also studied the morphology effect of CeO2 nano-shapes by keeping identical metal particle size on all three supports. The thesis is mainly divided into two parts, studying the morphology and particle size effects using Ru/CeO2 (chapter 2 and 3) and Ni/CeO2 (chapter 4) catalysts.

Joline Roemers - van Beek promoted Februari 16th 2018The work in this thesis explores a novel catalyst support design. In this design a macro-porous basis is used to immobilize a layer of carbon nanofibers (CNFs) agglomerates with the possible addition of a grown CNF binder layer. The synthesis of this grown CNF binder layer poses additional fundamental questions on CNF growth.
The produced catalyst support is tested for activity and selectivity in a fast
heterogeneous reaction, in this case nitrite hydrogenation in liquid phase.

Marijana Kavacevic Promoted June 1st 2016In this thesis we investigated CO2 mediated ethylbenzene dehydrogenation (EBDH) as a model reaction in order to probe intrinsic surface reactivity of tailored cerium oxide nanoparticles.

Roger Brunet Espinosa promoted June 3rd, 2016This work aimed at fabricating structured catalytic reactors for fast multiphase reactions, namely, nitrite hydrogenation and H2O2 decomposition. These reactors allowed a better understanding of these reactions and an improvement in terms of catalytic activity and selectivity.

Kamila Koichumanova promoted October 7th, 2015Many industrial processes produce large quantities of waste water containing all kinds of chemicals. These contaminated water streams can be used to produce hydrogen gas with help of catalysts without vaporizing the water. However, the conversion of the available chemicals into hydrogen is a difficult process, and in order to make it efficient, a detailed understanding of the chemical reactions taking place on the surface of the catalyst is required. A device, designed by Kamila Koichumanova from UT research institute MESA+, can supply important new information about this process. It enables scientists to observe what happens at the catalyst surface during the reaction in liquid water, so that they are able to improve the catalyst and the conditions of the reaction.

Jie Zhu promoted September 16th, 2015This thesis describes the preparation of stable CNF layers depositing on the surface of titania extrudate (CNF/TiO2) and cordierite monolith (CNF/TiO2/monolith) and their application as catalyst supports for selective hydrogenation of citral, cinnamaldehyde (CAL) and 4-carboxybenzaldehyde (4-CBA).

Hrudya Nair promoted January 29th, 2015The subject of this thesis is the direct synthesis of well-adhesive carbon nanofiber (CNF) layers via thermal catalytic chemical vapor deposition. The aim is to grow spatially uniform CNF layers with controllable morphology and controllable wettability on Si based Ni thin film substrates. This thesis also discusses the evaporation of water droplets on this CNFs as well as the impact of droplets and the subsequent spreading behavior on heated CNF surfaces. The results of these investigations are summarized in this chapter and an outlook is formulated.

Yingnan Zhao promoted January 15th, 2015Nitrate and nitrite contamination of groundwater is threatening the safety for supply of
drinking water in many areas all over the world, mainly caused by over-fertilization in modern
agriculture. Catalytic nitrate hydrogenation has been developed as an efficient and inexpensive
way to remove nitrate and nitrite contamination in drinking water. In these reactions, nitrate
can be reduced to nitrogen (N2) using bimetallic hydrogenation catalysts, with nitrite as an
intermediate product and ammonium as by-product. Pd catalysts have been found most
efficient for nitrite hydrogenation. A high selectivity to N2 of the catalyst is required, because
ammonium is also harmful in drinking water.