Show simple item record

dc.rights.licenseCC-BY-NC-ND
dc.contributor.advisorHoeven, Jessi van der
dc.contributor.authorJonasse, Just
dc.date.accessioned2024-02-15T14:50:44Z
dc.date.available2024-02-15T14:50:44Z
dc.date.issued2024
dc.identifier.urihttps://studenttheses.uu.nl/handle/20.500.12932/45960
dc.description.abstractThe conversion of CO2 into CH4 using H2 can become an important part of the reduction of our carbon footprint, turning a `waste' molecule into a usable feedstock. This reaction can be catalysed by nickel (Ni) nanoparticles (NPs). The behaviour of supported nickel catalysts depends on many factors, such as nickel nanoparticle size and the type of support used[1]. The preparation of monodisperse Ni nanoparticle catalysts with well-dened particle sizes on various types of supports is dicult using standard catalyst preparation methods, thereby hampering our understanding and the development of Ni catalysts for CO2 hydrogenation. A promising approach to address these challenges is the use of colloidal synthesis, where the metal nanoparticles are prepared separately before depositing them on a support[2]. This thesis demonstrates the successful application of colloidal synthesis to prepare Ni nanoparticles supported on several materials. Control over the size of Ni nanoparticles is typically achieved using phosphorous containing ligands. However, these ligands are dicult to remove from the Ni NP surface even at high temperatures (500 °C) and phosphorous often is incorporated in the Ni nanoparticles. In this work we present the synthesis of phosphorous-free Ni nanoparticles via colloidal synthesis. Using a literature procedure, monodisperse phosphorous-free Ni nanoparticles of 4 and 7 nm were synthesized suspension using a seed-mediated approach by reduction of Ni(acac)2 using a borane tert-butylamine complex[3]. The Ni NPs dispersed in toluene were deposited on a carbon or silica support via sonication-assisted deposition and rapidly dried. 4.2 0.9 nm Ni/SiO2, 4.9 0.8 nm Ni/C, 8.8 2.8 nm Ni/SiO2 and 8.0 1.7 nm Ni/C were successfully obtained in this manner. A mild thermal treatment was developed in this thesis, comprising a calcination step in O2 at 250 °C and a subsequent reduction step in H2 at 350 °C. Successful ligand removal on both support types was conrmed by IR spectroscopy and TGA-MS. Oxidation and reduction behaviour of the Ni NPs was extensively investigated using (in situ) TEM, TPR and XRD. Catalytic activity and catalyst stability were tested for Ni/SiO2 and Ni/C during high pressure CO2 hydrogenation at 30 bar and at temperatures varying from 240 °C to 340 °C, revealing much higher activities for silica support Ni NPs compared to carbon supported nanoparticles. Signicant sintering was observed for the Ni NPs supported on SiO2, leading to Ni NPs of up to 100 nm. A comparable colloidal synthesis using TOP was performed to investigate the potential dierence caused by changing this ligand. This resulted in the formation of nanoparticles containing phosphorous, which were not active for the reaction. This again illustrates the importance of developing a synthesis method to created Ni nanoparticles without using phosphorous containing ligands.To conclude, our methodology can be extended to other supports, and allows detailed investigations of the Ninanoparticle size- and support eects on the catalytic conversion of CO2 to CH4.
dc.description.sponsorshipUtrecht University
dc.language.isoEN
dc.subjectThe project consisted of controlled colloidal synthesis of Ni nanoparticles without making use of phosphorous containing ligands, their deposition onto different support materials and their performance in high pressure CO2 methanation.
dc.titleInvestigation into the preparation of supported nickel nanoparticles for CO2 hydrogenation via colloidal synthesis
dc.type.contentMaster Thesis
dc.rights.accessrightsOpen Access
dc.subject.keywordsColloids;Nickel;CO2 methanation;TEM;Catalysis;
dc.subject.courseuuNanomaterials Science
dc.thesis.id2798


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record