The reactions of ethanol over M/CeO2 catalysts: Evidence of carbon–carbon bond dissociation at low temperatures over Rh/CeO2 |
| |
Authors: | A Yee S J Morrison H Idriss |
| |
Affiliation: | Materials Chemistry, Department of Chemistry, The University of Auckland, Private Bag 92019, Auckland, New Zealand |
| |
Abstract: | The reactions of ethanol over Rh/CeO2 have been investigated using the techniques of temperature programmed desorption (TPD) and FT-IR spectroscopy, in addition to steady state catalytic tests. A comparison with previous studies of ethanol adsorption over Pd/CeO2 J. Catal. 186 (1999) 279] and Pt/CeO2 J. Catal. 191 (2000) 30] catalysts is presented. The apparent activation energy for the reaction was 49, 40, and 43 kJ mol?1 for Rh/CeO2, Pd/CeO2 and Pt/CeO2, respectively, while the turnover number (TON) at 400 K was 5.9, 8.6 and 2.6, respectively. Surface compositions of catalysts were characterised by XPS. A decrease of the atomic O(1s)/Ce(3d) ratio of the CeO2 support indicates its partial reduction upon addition of the noble metal. The extent of reduction per metal atom was in the following order: Pt>Pd>Rh. FT-IR and TPD studies have shown that dehydrogenation of ethanol to acetaldehyde occurred over Pd/CeO2, Pt/CeO2 and Rh/CeO2. Moreover, Rh/CeO2 readily dissociated the C–C bond of ethanol at room temperature to form adsorbed CO (IR bands at 1904–2091 cm?1). This was corroborated by the low desorption temperature of CH4 over Rh/CeO2 (450 K) when compared to that of Pd/CeO2 (550 K) or Pt/CeO2 (585 K). |
| |
Keywords: | Ethanol dehydrogenation TPD-ethanol Rh/CeO2-ethanol Ethanol-IR C---C bond |
本文献已被 ScienceDirect 等数据库收录! |
|