Solid state NMR characterisation of the thermal transformation of Fuller's Earth

• Published in: Solid state nuclear magnetic resonance Vol. 9; no. 2; pp. 257 - 267
• Main Authors: Drachman, S.R., Roch, G.E., Smith, M.E.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.12.1997
• Subjects: Aluminum; Aluminum Compounds - chemistry; Dehydroxylation; Fuller's Earth; Isotopes; Magnesium Compounds - chemistry; Magnetic Resonance Spectroscopy; NMR; Silicates - chemistry; Silicon; Temperature; Thermal transformation; Dehydroxylation; NMR; Fuller's Earth; Thermal transformation
• ISSN: 0926-2040; 1527-3326
• DOI: 10.1016/S0926-2040(97)00069-6

Fuller's Earth, a dioctahedral calcium montmorillonite clay mineral of the smectite group, undergoes thermal transformation via a series of complex intermediate states that are highly structurally disordered. Fuller's Earth is a commercially significant material with considerable levels of paramagnetic iron (Fe 3+) substitution into octahedrally coordinated metal sites. Despite the high iron-content (~ 10% of the occupied octahedral metal sites) in these samples 29Si and 27Al magic angle spinning (MAS) NMR spectra of sufficient quality are obtained to reveal structural changes in samples that have been heated from room temperature to 1400 °C. Two major structural changes are clearly observed, initial dehydroxylation and then collapse of the layer structure into more highly connected silica-rich domains and an alumina-rich phase.