FT-IR Emission Spectroscopy Studies of Molybdenum Oxide and Supported Molybdena on Alumina, Silica, Zirconia, and Titania

Abstract

Fourier transform infrared (FT-IR) emission spectroscopy has been used to study both molybdenum oxide and supported molybdenum oxide catalysts. An infrared emission cell was specially designed to treat the samples in vacuo or in various gases over a wide temperature range (25–700°C). The experimental conditions including sample preparation, effects of temperature, and sample thickness on the emission spectrum are detailed. The infrared emission spectrum of pure MoO₃ was nearly identical to the spectrum obtained by the KBr disc transmission method. An infrared emission study on the reduction and the oxidation of molybdenum oxide is presented. In situ infrared emission spectra were recorded for supported molybdena on Al₂O₃, SiO₂, ZrO₂, and TiO₂ at elevated temperatures, and the nature of the molybdenum-containing species on these supports is discussed on the basis of the infrared emission results.