caa a22 4500 467953422 CHVBK 20180405193744.0 cr unu---uuuuu 170328e20050101xx s 000 0 eng 10.1007/s10562-005-0770-3 doi (NATIONALLICENCE)springer-10.1007/s10562-005-0770-3 (NATIONALLICENCE)springer-10.1007/s10562-004-0770-8 Axial variation of the oxidation state of Pt-Rh/Al2O3 during partial methane oxidation in a fixed-bed reactor: An in situ X-ray absorption spectroscopy study [Elektronische Daten] [J. Grunwaldt, A. Baiker] Probing the structure of materials in situ is of central importance in heterogeneous catalysis. Mostly, this is done in an integral manner, that is without spatial resolution. However, at high conversion in a catalyst bed prominent concentration and/or temperature profiles may exist which can result in significant spatial variation of the catalyst structure. In the present study, X-ray absorption spectroscopy combined with on-line mass spectrometry was used to monitor the structural changes of a Pt-Rh/Al2O3 catalyst in a fixed-bed reactor during partial oxidation of methane. The reaction ignited at 310°C and integral X-ray absorption spectroscopy showed that the Rh-Pt-particles were reduced at the same time. However, monitoring with a beam of 1mm×0.6mm size along the axial position of the catalyst bed uncovered that Rh and Pt were still in oxidized state in the entrance region, whereas they were in reduced state in the zone at the end of the catalyst bed. The gradual transition from the reduced to the oxidized state was found to shift towards the bed entrance if the temperature was slightly increased. Springer Science+Business Media, Inc., 2005 partial oxidation of methane nationallicence Pt/Rh catalyst nationallicence X-ray absorption nationallicence Grunwaldt J. Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hönggerberg HCI, CH-8093, Zurich, Switzerland aut Baiker A. Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hönggerberg HCI, CH-8093, Zurich, Switzerland aut Catalysis Letters Kluwer Academic Publishers-Plenum Publishers 99/1-2(2005-01-01), 5-12 1011-372X 99:1-2<5 2005 99 10562 https://doi.org/10.1007/s10562-005-0770-3 text/html Onlinezugriff via DOI 1 other jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10562-005-0770-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Grunwaldt J. Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hönggerberg HCI, CH-8093, Zurich, Switzerland aut NATIONALLICENCE 700 1- Baiker A. Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hönggerberg HCI, CH-8093, Zurich, Switzerland aut NATIONALLICENCE 773 0- Catalysis Letters Kluwer Academic Publishers-Plenum Publishers 99/1-2(2005-01-01), 5-12 1011-372X 99:1-2<5 2005 99 10562 NATIONALLICENCE 856 40 https://doi.org/10.1007/s10562-004-0770-8 text/html Onlinezugriff via DOI Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE NATIONALLICENCE NL-springer