IR characterization of propane oxidation on Pt/CeO2–ZrO2: The reaction mechanism and the role of Pt

In order to investigate the reaction pathway of propane total oxidation on Pt/CeO2–ZrO2 (Pt/CZ) catalyst and the promoting effect of Pt, CeO2–ZrO2 (CZ) mixed oxides were prepared by sol–gel method and Pt was impregnated. The catalysts were characterized by means of XRD, BET, TPR, in situ FTIR spectroscopy of propane adsorption/transformation/desorption and propane catalytic oxidation activity experiments. The propane oxidation activity is greatly enhanced by the addition of Pt while there is no obvious structure change based on XRD and BET. It is shown by the adsorption experiments that at 250 °C, propane can react with oxygen-containing species; there is obvious destruction of CeO bonds, from which oxygen consumption can be inferred, on both CZ and Pt/CZ catalysts, as well as the generation of some bicarbonate ions on CZ and carbonate on Pt/CZ. Moreover, there are more δ(CH) and δ(CH2) species on CZ than Pt/CZ. When oxygen was introduced into the reactor, the CeO bonds re-formed immediately on Pt/CZ but not on CZ. The propane desorption results show that the intermediate products and desorption process are almost the same on both catalysts. Furthermore, some bidentate carbonate has been detected on both catalysts during the total oxidation process, and it is thought to be the intermediate product of the reaction. Based on the IR results, a possible propane oxidation pathway and the role of Pt as well as the possible electrochemical mechanism have been proposed.

Figure optionsDownload high-quality image (84 K)Download as PowerPoint slideHighlights
► The addition of Pt increases propane oxidation activity at the low temperature.
► The oxidation of Ce3+ and regeneration of Ce4+ is important to the oxidation reaction.
► Bidentate carbonate species are thought to be the intermediate of the oxidation reaction.
► The desorption of products is mainly related to CeO2–ZrO2 support.