| This thesis focuses on the studies of the interaction between Rh and Al2O3 on the performance of the Rh/Al2O3 catalysts for methane partial oxidation (POM) to synthesis gas. In the first part of the paper, we prepared a serial of Rh/Al2O3 catalysts calcined at different temperatures (dried at 110℃ or calcined at 600℃and 900℃) and with different Rh loadings (0.1 - 3wt%). The sample's surface area and bulk structure were characterized by BET and XRD techmques. Catalytic performance of the catalysts for the POM to synthesis gas was also investigated in detail. It was found that, for the reaction over the Rh/Al2O3 catalysts calcined at the same temperature, the ignition temperature of the POM reaction decreased with the increasing of Rh loadings in the catalysts. For the POM reaction over the catalysts with high Rh loadings, steady-state reactivity was observed. For the reaction over the catalysts with low Rh loadings, however oscillations were observed during the reaction. For the reaction over the Rh/Al2O3 catalysts with same Rh loadings, the ignition temperature of the POM reaction increased with the increasing of calcination temperature, and the oscillations during POM reaction were apt to occur over the catalyst calcined at high temperature. We also found that the oscillation during the POM reaction could be inhibited by increasing the reduced temperature or reaction temperature.In the second part of the paper, comparative studies using chemisorption (H2, O2 and CO), H2-TPR, O2-TPD and high temperature in situ Raman spectroscopy techniques were carried out in order to elucidate the relation between the redox property on the Rh species in the Rh/Al2O3 and the performance of the catalysts for POM reaction. Three kinds of Rh species, i.e. the rhodium oxide species insignificantly affected by the support (RhOx), that intimately interacting with the Al2O3 surface (RhiOx) and the Rh(AlO2)y species formed by diffusion of rhodium oxides in to sublayers of Al2O3, were identified by H2-TPR and O2-TPD. Among them, the first two species can be easily reduced by H2 at temperature below 300℃, while the last one can only reduced by H2 at temperature above 500℃. The ignition temperatures of the POM reaction over the catalysts are closely related to the redox property on RhOx and RhiOx species. Compare with the rhodium species over the catalysts calcined at low temperature or with high Rh loading, those on the catalysts calcined at high temperature or with low Rh loading possess stronger Rh-O bong strength and are more difficult to reduce to metal. Higher temperature is therefore required to ignite the POM reaction over the catalysts calcined at high temperature or with low Rh loadings. A quadrupole mass spectrometer was used to follow the oscillations in the reactants and products during the POM reaction over the Rh/Al2O3 catalysts. It was found that the oscillations in the signals of reactants and complete oxidation products (CO2 and H2O) are in-phase with the temperature at the entrance of catalyst bed, while being out-of-phase with the signal of the POM reaction products (CO and H2) and the temperature at the rare end of catalyst bed. The oscillation during the POM reaction over the Rh/Al2O3 can be related to the behavior of Rh(AlO2)y species in the catalysts switching cyclically from the oxidized state to the oxidized state to the reduced state during the reaction .
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