Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Surface Chemical Reactions and Heterogeneous Catalysis I
O 8.1: Vortrag
Montag, 11. März 2013, 10:30–10:45, H33
Influence of the nanometer scale on the reactivity of cerium dioxide — •Kostiantyn Kulyk and Mykola Borysenko — Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, General Naumov Str. 17, 03164 Kyiv, Ukraine
Cerium dioxide is considered as the most widely used rare-earth oxide in industry due to its unique redox properties and elevated oxygen storage capacity. However, the preparation of ceria nanoparticles with desired size still remains a challenge and to date little is known about how the nanometer scale of the ceria particles effect its chemical behavior. My talk will illustrate the crucial points of our novel method of synthesis of ceria nanoparticles supported on fumed silica. The proposed method allows us to synthesize nanocomposites with a controllable size of cerium dioxide crystallites from 3 to 24 nm (XRD, Solid State MAS 29Si NMR, Raman, IR, SEM, UV-vis). Comparison of reactivity of nanosized CeO2 and micrometer scale CeO2 will be demonstrated by studying the interaction of nanocomposites with cerium acetylacetonate, acetylacetone, acetic acid, thiazolyl- and benzothiazolyl substituted coumarines. Mechanisms and kinetics (n, Eact, ko, dS) of surface reactions were studied using a temperature programmed desorption mass spectrometry (TPD-MS) and TG/DTG/DTA. The main part of my speech will be devoted to the phenomena of dramatic enhancement of the reactivity of ceria nanoparticles resulting in its ability to chemisorb acetylacetone at room temperature and form grafted ceriumacetylacetonate groups. The mechanism of the nanoeffect will be presented and described in details.