Oxidation and Reduction of MoO2–MoO3 Studied by Infrared Emission Spectroscopy

Abstract A sample preparation technique was developed for the study of infrared emission spectroscopy. The emission spectrum of MoO3 showed peaks at 987 and 925 cm−1 in the temperature range of 185 through 505 °C. Peak intensities were proportional to the sample weight. The background intensity in the emission spectrum was measured at 1050 cm−1 and it was also proportional to the sample weight. In order to apply emission spectroscopy to the study of reaction kinetics, the reduction of MoO3 by H2 and the oxidation of MoO2 by O2 were chosen as model reactions. These reactions were studied at 425 to 485 °C and the activation energy for the reduction of MoO3 was 43 kcal/mol and that for the oxidation of MoO2 was 38 kcal/mol. The activation energy for the formation of the terminal Mo=O bond was, however, 71.2 kcal/mol.