A Study of the Iron/Sodalite Catalyst for the Partial Oxidation of Methane to Methanol

Abstract

The synthesis, characterisation and reactivity of an iron/sodalite catalyst for the partial oxidation of methane to methanol are described and discussed. In a limited temperature range, ca. 410°C, and at 34 bar total pressure, the selectivity to methanol is found to be similar to that observed for the empty silica glass reactor. Before reaction, powder X-ray diffraction and ⁵⁷Fe Mössbauer spectroscopy confirm the presence of Fe(III) in the sodalite framework. After reaction the structure is more complex, as revealed by ⁵⁷Fe Mössbauer spectroscopy and transmission electron microscopy, and both Fe(II) and Fe(III) are present. In particular, small particles of Fe₂O₃, < 1μm in size are also present in the used catalyst. The nature of the active site is discussed in terms of an Fe(II)/Fe(III) couple involving both framework and nonframework iron.