Hidrotermalna sinteza dopiranog nanokristaličnog CeO2

master's thesis

• Title (english): Hydrothermal synthesis of doped nanocrystalline ceria
• Author: Martina Guliš
• Mentor: Stanislav Kurajica (mentor)
• Committee member: Stanislav Kurajica (predsjednik povjerenstva)
• Committee member: Vesna Tomašić (član povjerenstva)
• Committee member: Juraj Šipušić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2017-09-25, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Basic Technical Sciences; Materials

Abstract

Pripravljeni su i karakterizirani uzorci čistog i dopiranog cerijeva (IV) oksida, CeO2, te je testirana njihova katalitička aktivnost u procesu katalitičke oksidacije toluena koji je upotrijebljen kao modelni hlapljivi organski spoj. Provedena je serija sinteza nanočestica čistog CeO2 i dopiranog CeO2 sa 10 % množinskog udjela sljedećih dopanada: Mn, Fe, Co, Ni, Cu, Zn, Cd i Al. Hidrotermalna sinteza provedena je bez ikakvih aditiva koji bi smanjili katalitičku aktivnost i mogli biti štetni za okoliš. Pripravljeni uzorci te uzorci zagrijavani 2 h na 500 °C analizirani su rendgenskom difrakcijom. Veličina kristalita izračunata je pomoću Scherrerove metode. Odabrani uzorci analizirani su infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR), energijskom razlučujućom rendgenskom spektroskopijom (EDX), transmisijskim elektronskim mikroskopom visoke rezolucije (HR - TEM), spektroskopijom gubitka energije elektrona (EELS) te su određene N2 adsorpcijske / desorpcijske izoterme. Katalitička aktivnost je utvrđena na temelju oksidacije toluena u cijevnom reaktoru s nepokretnim slojem katalizatora, CeO2. Dobiveni rezultati pokazuju kako su Mn, Cu i Zn uspješno dopirani u kristalnu rešetku te nisu dobivene dodatne kristalne faze na difraktogramima. Kod dopiranja s ostalim metalnim kationima dolazi do nastanka dodatnih kristalnih faza, no ti rezultati ne isključuju ulazak kationa u rešetku. Dobivene veličine kristalita pripravljenih uzoraka čistog i dopiranog CeO2 nalaze se između 3 - 5 nm, dok su iste nakon termičke obrade između 9 - 17 nm. Veličina kristalita odgovara rezultatima dobivenim transmisijskom elektronskom mikroskopijom. CeO2 dopiran s Cu i Mn pokazao je značajnu katalitičku aktivnost za oksidaciju toluena. Uzorci dopirani sa Fe, Ni i Zn nisu pokazali značajno unaprjeđenje katalitičke aktivnosti dok su uzorci dopirani s Cd, Co i Al pokazali smanjenje katalitičke aktivnosti tijekom oksidacije toluena.

Abstract (english)

Pure and doped nanocrystalline ceria have been prepared, characterized and tested for catalytic activity in process of catalytic oxidation of toluene as volatile organic compound model. A series of hydrothermal synthesis was performed and the products were pure ceria and doped ceria where 10 at. % of Ce was replaced with Mn, Fe, Co, Ni, Cu, Zn, Cd and Al. Hydrothermal synthesis was performed without additives which would reduce the catalytic activity or could be toxic for the environment. The prepared samples and samples thermally treated at 500 °C for 2 h are studied by X-ray diffraction (XRD). Average crystalline sizes were calculated using Scherrer’s method. Selected samples were also analyzed with Fourier transformation infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), electron energy loss spectroscopy (EELS) and N2 adsorption/desorption isotherms. Catalytic activity was tested based on the toluene oxidation process in a tube reactor with a fixed catalyst layer. The obtained results show that Mn, Cu and Zn were successfully incorporated into the crystal lattice without additional crystalline phases, while for other investigated metals additional crystal phases appear. Crystallite sizes of prepared doped ceria samples were between 3 and 5 nm, while thermal treatment causes the increase in crystallite size to a range between 9 and 17 nm. Crystallite size matches well with particle size determined using TEM. CeO2 doped with Cu i Mn showed significant catalytic activity for process of toluene oxidation. Samples doped with Fe, Ni and Zn did not show significant advancement of catalytic activity while samples doped with Cd, Co and Al showed a decrease in catalytic activity for toluene oxidation process.

• Keywords: hidrotermalna sinteza; nanočestice CeO2; dopirani CeO2; prijelazni metali; katalitička aktivnost; toluen
• Keywords (english): hydrothermal synthesis; nanocrystalline ceria; doped ceria; transition metals; catalytic activity; toluene
• Language: croatian
• URN:NBN: urn:nbn:hr:149:556124
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-04-22 12:17:12