First Steps on the Way to a Modular Concept for the Preparation of Carbon Based Catalysts
- PDF / 615,620 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 29 Downloads / 171 Views
First Steps on the Way to a Modular Concept for the Preparation of Carbon Based Catalysts Reni Walter • Olaf Klepel • Thomas Erler Michael Bron • Paula Niebrzydowska • Anna Wach • Piotr Kus´trowski
•
Received: 3 February 2013 / Accepted: 26 April 2013 / Published online: 9 May 2013 Ó Springer Science+Business Media New York 2013
Abstract The preparation of carbon based catalysts following a modular concept has been investigated. A template assisted route was applied to obtain catalysts exhibiting different fractions of graphitic species while retaining their mesoporosity. The carbon materials were characterized by means of low temperature nitrogen adsorption, powder X-ray diffraction, thermogravimetry, X-ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectroscopy. The synthesized replicas were tested as catalysts in oxidative dehydrogenation of ethylbenzene and electrochemical oxygen reduction reaction. The role of the different carbon species, namely amorphous carbon, small graphitic crystallites, and large graphitic crystallites in the catalytic behavior was discussed. Keywords Heterogeneous catalysis Catalysis Dehydrogenation Processes and reactions Nanostructure
1 Introduction Carbon catalysts are widely investigated for several redox reactions such as the oxidative dehydrogenation (ODH) of
R. Walter O. Klepel (&) Faculty of Natural Sciences, Lausitz University of Applied Sciences, P.O.B. 101548, 01958 Senftenberg, Germany e-mail: [email protected] T. Erler M. Bron Department of Chemistry, Faculty of Natural Sciences II, Martin-Luther-University Halle, 06099 Halle (Saale), Germany P. Niebrzydowska A. Wach P. Kus´trowski Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland
123
hydrocarbons [1–5] or the electrochemical oxygen reduction reaction (ORR) [6–13]. Both processes are of eminent scientific and industrial interest. While the oxygen reduction is one of the electrode reactions in fuel cells, the ODH is being investigated as a thermoneutral alternative to the industrially applied endothermic dehydrogenation. There is a special interest in the catalytic activity of graphite derived carbon nanostructures, e.g. onion-like, stacked cups, stacked platelets or just graphite crystallites [3, 10]. In general, such structures are built up of (curved) basal planes and edge planes. The edge planes are more active in redox reactions than the basal planes due to more readily chemisorbed oxygen [10]. However, the basal planes are required to activate molecular oxygen due to the splitting of the dioxygen double bond by delocalised electrons [14]. A sufficient size of the graphene planes is necessary to provide delocalised electrons which are more weakly bound than in aromatic molecules [14]. These activated oxygen species can then migrate to sites at the edge planes to form oxygen functionalities. Since these functionalities can act as the catalytically active sites one can conclude that catalytically active carbons are characterized by
Data Loading...
