A STUDY OF THE EFFECT OF SULFATION ON IRON-OXIDE CATALYSTS FOR METHANE OXIDATION

Sulphated and non-sulphated iron oxides derived from goethite have bee n compared as methane oxidation catalysts. It has been observed that s ulphation increases surface area, suppresses low temperature total oxi dation and enhances the formation of partial oxidation products. Chara cterisation of these materials prior to activity testing demonstrates that, although transformed into haematite, both exhibit a relic morpho logy related to that of their precursor and that sulphation causes ext ensive pitting of crystallites. Analysis of powder X-ray diffraction p atterns indicates that the relic morphology is multidomainic and that sulphation increases line widths in relation to the non-sulphated syst em. The post-reactor sulphated samples were found to have lost crystal linity and both catalysts had changed phase from haematite to maghemit e. (C) 1998 Elsevier Science B.V. All rights reserved.