AL-27 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY INVESTIGATION OF THERMAL TRANSFORMATION SEQUENCES OF ALUMINA HYDRATES .2. BOEHMITE, GAMMA-ALOOH

被引:31
作者
SLADE, RCT [1 ]
SOUTHERN, JC [1 ]
THOMPSON, IM [1 ]
机构
[1] ALCAN CHEM LTD,GERRARDS CROSS SL9 0QB,BUCKS,ENGLAND
关键词
ALUMINA HYDRATE; BOEHMITE; PSEUDOBOEHMITE; CALCINATION; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY;
D O I
10.1039/jm9910100875
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
High resolution Al-27 magic-angle spinning nuclear magnetic resonance (MAS NMR) (78.15 MHz) spectra are reported for boehmite and pseudoboehmite and for calcines occurring in their thermal transformation sequences (involving gamma, delta, theta and alpha-aluminas). Spectra for boehmite, pseudoboehmite and corundum (alpha-alumina) are fully consistent with the known use of only octahedral aluminium (AlO6) sites. Spectra for gamma-aluminas are consistent with defect spinels, with the extent of disorder dependent on precursor material and calcination conditions. delta-Alumina either retains approximately cubic close packed (c.c.p.) oxygens (with aluminium atoms on both spinel and non-spinel octahedral and tetrahedral interstices) or may contain some five-co-ordinate Al (AlO5) in addition to AlO6 and AlO4 environments (and hence have oxygen packing deviating from c.c.p.). Aluminiums in low-symmetry sites manifest themselves instrumentally for the most disordered systems as wings extending to either side of the central spectrum.
引用
收藏
页码:875 / 879
页数:5
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